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Les diagrammes suivants illustrent la metiiode. 1 2 3 4 5 6 MICROCOPY RESOLUTION TEST CHART ANSI end ISO TEST CHART No 2 1.0 I.I li^r-s m f. 3 2 2.2 2.0 1.8 1.4 1.6 ^ ^ppuEmtyMGE_jn ~-= ■ i-.esi*". New -sfh i^rc. r'a ' '^j *B2 - OJOO Phore ^= ft) 2M - ^989 -fon < z o z o Q Z < z o I ills liooK l).' liirkiii^r. 'I'ln' only hook lierotoforo issued was written four years ago, and is now out. of date. In V.)\2 tlie flotation proeess had hardly won a foothold in the I'nited States; today fully oO.OOO tons of ore is heiiKj treated daily by the frotliinp or bubhle-Ievitation method. In July l!*!;") the Mining ami Scii ntific I'n ss hr(;aii to pnhlish a series of artieles desorihing eurrent progress in this new hraneh of metallurgy. These were followed tiy a nuinher of interesliiiff eontrihutions on the theory of the snlijeet. All of them are reproduced in this volume. Tliey elaim no finality. The physics of flotation is .still a riddlf un- solved; but the betrinnings of investination have been made. In the pages that follow will be found Uie rudiments of a connected theory explaining the phenomena underlying the life and activity of the metallurgic bubble. In preparing this volume, I am under plejisant obligation to the various contributors; it will not be deemed invidious if I express special indebtedness to Messrs. 0. C. Ralston. ('. T. Durell. Dudley H. Norris, and Will II. Coghill. The reader will be particularly grateful to Mr. Ralston, of the U. S. Bureau of Mines, for his invaluable article on the testing of ores by flotation and for his resume of preferential methods. Messrs. Durell. Norris. and Coghill have helped to clarify many obscure points. To the anonymous metallurgist who wrote on the experiments at the Mexican mill an^25B ?t" H.^r' I ,>-V-_..-:. lABI E OF" CON I tlN TS Pbkp. A (iloxsaiN of Fliiiiiliiiii The Kloliilion I'kkohh ''■. .1. Uirknul Klotatioii Ttsts al Moiiiit Moikhii Ui.7ir;m Mothiriirtl Oils I'setl ill llii- Klotiilidii I'rofcsrt DrnniDiidl Cnnlnlnitur Klotiilion (if Ciiiip*'! Oi'^x •' W. <'"I'"U- IT.lVrcntial Kloiaiioii "■ '" Hnhton Kldtali 1 111'' liis|iiratii)ii Mine, Arizona ■WinCim Mulhrruit' Hdialloii ill a N.cxicaii Mill .s'/"'''"' ('"rnsix'iiihni Kioih and I'lotalion. . . . \V. /■'. C'>iiiUuiil. Dnny lliitlrr, (DuI Jus. if. W'lxr Klolalion at WmhIioc Hcdiictlon WorUs, Anaconda /•-' /'■ .Uathrirsun Flotation at the Cj-iitral Miiir, HidUimi Hill ./(/mi , Ihhhnnl What iH Flotation?- 1 T. A. Hvknnl \Vh> is Flotation?- I CliiirU:i T Diinll What is Flotation?— II T. ,1. Hi'knnt Surfare Tension and Salts in Solution Will If. i'lmfnU Air-Froth Flotation -I "' •'• ^''"" Why Do Minerals Float? Olinr c. fx'dlstoii Why Is Flotation'' — II ./rink'r The Klectrical Theorv of Flotation— I Thomas .V. lininn. .Ir. /. .u. r.i/;o»- Notes on Flotation Dis|iosal of Flotation Residue "'■ slirllslir.ir Th" Klectrical Theory of Flotation— II Thoiiuis M. lUiiiis. .Ir. Fffects of Soltihle Coniponetits of Ore on Flotation Occd.s-io/m! ('iirr< sixindi'iit Flotation — \ I'ar:i(lox t)ii from sinking, to keep afloat in a liquid. Co.M.r.Mi is a thick, black, viscid, and opaque liquid condensed when gas is distilled from coal. Such i>roducts consist of soluble and insoluble substances. Co.\c,ii,ATioN. The state of a liquid resulting from clotting or curdling, the act of changing to a curd-like condition. CoNtKNTR.\TK. To draw or gather together to a common centre. To re- duce to a purer state by the removal of non-essential matter. From L. ron or cum, with, and centrum, a centre. Co.NT.\MiN.\TK. To make Impure by contact or admixture. Er.KiTBO-sT.\Tics. That branch of electrical science devoted to ihe phe- nomena of electricity at rest or of frictional electricity. Kmii.sion. Milkification. A liquid mi.Kture in which a fatty or resinous substance is suspended in minute globules. From L. rmuJiio. to drain out, in turn from r. out, and mulgco. milk. Efc.M.Yi'Tis on.. The oil distilled from one of the Australian gum-trees, the cutnlyptus amyijdaUna. Fat is a white or yellowish substance forming the chief part of adipose tissue. It may be solid or liquid; it is insoluble in water; when treated with an alkali, the fatty acid unites with the alkaline base to make soap. Film. A coating or layer, a thin membrane. Fi.odii.KNT means resembling wool, therefore woolly. Coalescing and adhering in Hocks. A cloud-like mass of i)recipitate in a solution From I., floctus, a lock of wool. Flotation is the act or state of floating, from the French fluttnUiov. water-line, and fluttir. to float, to waft. Fr.oiATioN-KKKi). The crushed ore. jiulp, or other mill-product that goes for treatment to the flotation plant. FiioTit. A collection of bubbles resulting from fermentation, efferves- cence, or agitation. Ganci K. The non-metalliferous or non-valuable metalliferous minerals In the ore; veinstone. (iRAMiAiuiN is the state or process of being formed into grains or small Ijarliiles. From L. granum. a grain. C.iUAsi:. Animal fat when soft. Also anything oily or unctuous. From the French graisse. I.EMT.vTioN. The act of rendering light or buoyant. L. h-vitnit. light- Metai.i.ic. Of or belonging to metals, containing me*. Is, r. ore particu- larly the valuable nipfals that are the oliject of mining. Kroni I., nifl'illinn. ore. MiNKKAL. Iiiornaiilc constinient of the earth's crust. A3 used in flota- tion the terms iiiineral' or 'metallic' iiarticles hark bark to the French (miHOdi, ore! and S|ianish {jhetal, ore) meanings. Both terms refer lo those valuable constituents in the ore that it is tho object of the process to separate from the non-valuable constituents, or gangue. Sometimes 'metal- lic' has reference to metallic lustre, one of the chief characteristics of metals and more particularly of those metallic sulphides that are especially amenable to flotation. .MipMiKv. To change in character or properties. Mcii.K.( I i.K. The smallest part of a substance that can exist separately and still retain its composition and characteristic properties: the smallest combination of atoms that will form a given chemical cunipoiind. From F. viiih'i iilr. diminutive from L. iiioU's, mass. N.v.sctNT. Coining into licing, beginning to develop. From L., /uisicns. being born. Oi cii iiK. To shut or close pores or other oi)enings. From 1... ob. before, claudu. close. Oil ic .\i 11) is fatty acid contained in olive oil combined with cresoliue. zMtlioimh called 'acid' it is an oily substance and functions as oil in flota- tion operations; it is contained in most mixed oils and fats, from which it is obtained by siiponitication with an alkali. From L. nh-iun, oil. On, includes (ll fatty oils and acids, (2) essential oils, luoslly of vegetal origin, such as eucalyptus and iurpentin'\ (3) mineral ous, such as pell oleum products, including luliricating oils, Oii.v and Gkk.vsv are sulistaniially equivalent terms. .-\11 oils are greasy. Greasiness suggests more viscidity than oiliiiess. Os.\io>K. The tendency of two liquids or gases to mix by passing through a membrane or porous wall separating them. From O. osinos. pushing. FiM.oii, is a derivative of wood-tar, as phenol and cresol are derivatives of coal-tar. Piir is powdered ore mixed with water. S.M'dMiu MioN, Conversion into soa|i; the process in which fatty sub- stances form soap, by combination with an alkali. From L. xnpu (n-), soap. Set \i. Imjnire or extraneous matter that rises or collects at the surface of liquids, as vegetation on stagnant water, or dross on a bath of molten metal. Ski.n. All outside layer, coat, or covering. From A. S. siiiui, ice. Si'ir/K \siKN. A iioiiited box or inverted iiyiamidal vessel, with an out- let at its point for the separation of the components of an ore by gravity. German, spitze. point, ktistcii. chest. SiRK.vtK TK.Nsiu.N IS the contractile force tit the surface of a liquid where- by resistance is offered to rupture. Vksici K. A sn'all bladdei-lik. cavity or hollow sphere of liijuid. From rcsicM/d, diminutive from icsici. bladdt-r. VisKisrrv is the property of lioiiids that causes them to resist i'l^tan- taneous change of tlieir shape or of the arrangements of their jiarts; inurual friction: guniminess. l'"rom 1.. its(tiiii. birdlime. THE FLOTATION PROCESS By T. A. RicKAKii (From the Miniiiij and ^rirntiftc Pre.si of Maroh 4, IS, and April 1, 19U!) •Inteoductory. It is not yet four years since the starting of the first American mill using the frothing method of flotation, yet 55,000 tons of ore is being treated daily hy tills process in the Unitod States today. This means 20,000,000 tons per annum. Tiie larger part of these metallurgical operations began within the last two years. It is evident therefore that the process is gaining ground so rapidl,v as to command the intelligent attention of all thoso engaged in mining. In the present writing upon the subject I have tried to supply suen information as is required by those newly interested in flotation, I'ither as students or as operators. Of {•ourse. what I have written makes no claim to finality, for I am conscious of possessing only an elementar.v understanding of the exiremel.v abstruse set of phenomena underlying the process. 'My contribution is that of a detached ob- server, eager to be helpful to the workers in tins new branch of nietallurg.v. TiiK Physics. In a recent reminiscence my friend Ren Stanley Kevett has recorded' how he bet "a bottle of bubbles" with that pi'rii)atetic philosoplier Thomas F. Criley, the partner (•( Carrie Jane Hvcrson in an oil process of concentration whereby the valuable sul- phides were made to flo;it above the worthless gangiie in a pulp of cru.'ilH'd ore. JFr. Revett .says tliat he bet liis Inibbles against ('rih'.v's. but we suspect that in saying so he was interpreting the prior art in terms of latter-day me1allurg,v. for it is doulitful whether any of the persons concerned in tliiit early experiment at Raker City. Oregon, had a clear understanding of the function of the bubbles in assisting tile oil to give ])uo,vjiiie,v to tlie sul])hides. However, in staking bis biibliles of enrhon dioxide dissolveci under i>ressure in the vintage of Chaniiiagne against the performance predicated bv Crile.v, Jlr. Revett must be credited with su(>cessful anticipation, fcir 27 yenrs after the •This article wa.=; jiresfnted as a paper at the March (Ifllfil meotiiiR of the Caiiaflian Miiiinc Institute. 'Mhi:>i(/ ami Krimtifir Pri'ss. October Ifi, 1915. 9 10 THE FLOTATION PROCESS incident we know that the key to the flotation process is to lie found not in the oil, the acid, or the apparatus, hut in the bulihlcs. The man who understands the physics of a soap hutiMe has mas- tered the chief mystery of flotation. The small boy, who. as pictured by ]\lillais. watches the iiirth. a.scent, and bursting of the iridescent si)here of his own making, is the type of our modern metallurgist who makes the multitudinoiis bi.iibles constituting a froth and then won- ders to what laws of physics this tilmy product owes its existence. To i)Ut it bi'iefly. the boy. liaving dis.solved soap in water, Imhls a little of it in the bowl of his elay pipe while he blows through the stem. 'J'ue soa])y water forms a film that is distended by the boy's warm lireath into a lively sphere, which is lighter tlian the surround- ing air and therefore rises, while the sunshine undergoes refraction into the colors of the spectrum. When the boy blows through iiis pipe into i)uri_ water, he makes l)ubbles likewise, liut ilic.v lu'cak in- stantly. It is the soap that lengthens their life. In the language of physics we say that higli 'surface tcTisiou' causes tlie pure-wafer bubbles to burst immediately, while the addition of soap introduces a contaminant that lowers the tension so as to enable the bul)hles to last longer. The basic factor in the making of l)ulibl(>s is surface tension. This is the force that causes the surface of a liquid to resist mpturc. The particles at the surface liave a greater coherence than the similar par- ticles within the body of the licpiid. In other words, each molecule within the interior of tlie liquid may be pictured as surrounded by molecules like itself in being attracted toward each other e(|ually in all directions: while the molecules at the free surface of the liquid are aitraeted only by those internal to themselves, the result being to constrict the free surface to the least area. In consequence, the sui-face acts as if it were elastic. Hence the attachment of water to the sides of a tube and the drawing nf that water uj)ward — which is called •capillarity' because it is most marked in a tube as small as rapilJii'^. a liair. Numerous manifestations of surface tension on wafer could be cited. Fill a tumbler a little nn iv than full and the water will have a convex surface, indicating that there is some force at work to preve;il the w.'ifer from spilling. Note the cohesion between two plates that have been wetted. Dip a camel '.s-hair brush into water and the hairs ■■W;.^ jf,^^.i!.{.5=. inimcrse the -"-t ^ru=h in the wntrr rsrid ttm !;:!!•■'. sejiarate Wafeli tlie formation of a drop of vcater and Tiote flial it tiehaves as if envelo])ed by a stretched membrane. Water-spiders can THE FLOTATION PROCESS 11 be soon niiiiiiiig over tlie surface of a pond in summer, as small boys run over a jximi covered with i<-e iu winter. The ice bends under their weifrht witliout lircdking; so also the spider- makes a visible dimple without wetting his feet. The surface is not ruptured. The force of surface tension has been measured by ascertaining the weight that can be suspended from a lilm of water in air.-^ It has been stated as 3} grains per inch' or 81 dynes per centimetre.' The most recriit determination is tliat of Iheodore W. Pichards and Leslie B. ("oombs.'' who found it to be 72.62 dynes per cei in'c're at 20''C. Many disturbing factors enter into the me; urement of this force, so that divers figures, ranging from 70.6 to 81, have tieen announced at different times. Surface tension ditTers as between various liquids and fluids in contact ; for example, the tension separati'-.g mercury from water amounts to 418 dynes per centimetre, while that separating olive oil from air is only 1)6. !l dynes. A drop of pure water will spread over the surface of pure mercury as oil will spread over water. The sur- face tension of an oil-water surface is only 14, as compared with the 7.'i of an all-water surface at a temperature of 18''C.' While the film of oil on water may be only one molecule tliiek, or one twenty- five millionth of an inch, it will s'.iffice to reduce the etTective pull of the water surface from 73 to 43. This latter figure represents the efTectivc surface tension of water modified by oil as used in flotation. It is the main factor in the formation and persistence of a bubble. Heat lowers the surface tension of water. Place powdered sulphur on the surface of the water on a horizontal plate of clean metal : apjily heat locally: the sulphur is pulled away by the old liquid a.s against the feebler tension of the warmer liqiiid. This elastic force at the surface of a liquid tends to draw it into the most compact form. That is why a drop assumes the form of a .spiiere. in which sliapc it presents the smallest surface in relation to its volume. Surface tension is a contractile force. This is shown in a simpl.' way by blowing a soap Imbblc on the large end of a pipe and then liolding the other end of the pipe to a candle, when the air es^.iping from the shrinking bag of the bubble 2ln N'pw Knglaud the boys call them sknters.' •TA Text-Rook of the F-rinciples of Physics.' By Alfred nanniell, 1911. I'^In a chemically pure liquid it is imiKJssible to form froth or multiple bubbiinff. Some difTerentiation of the components of a liquid is required to make a film. 14 TIIK FLOTATION I'KOCKSS 111 liis liddk 'I'. -1. IIimivit" stiiti's hdW tlic prrM'iiic of d sutlicicntly to s-parale the metallic sulphides from the a.ssociated fjrnnfrue in a pulji consisting of minute particles of each. In ordinary water-conetMitra- tion the lower specific gravity of the gaiigue jiermits the mill-man to wasli it away from the heavier metallic sulphides, hut in the flota- tion jiroccss this action is reversed, the iiictalli<' particles hcing lifted ahove, and away from, the f,aiigue particles. Apparently, it is a metallurgic anomaly.'^ To this crashed ore we have added oil. The oil serves as a con- taminant that lowers the surface tension: als<' it augments the vis- cosity of the liquid. These two effects unite in facilitating the forma- tion of strong and persistent huhhies. The necessary air is introduceii hv agitation or h.v direct injection. Kea-weed contaminates sea-water and makes foam in the lireakei's. as oil makes froth in fresh water that is agitated. Air hius a marked adhesiveness for metallic surfaces: this attach- ment is supposed to he enhanced hy the presence of oil or grease on the metallic surface. In other words, the metallic surface, such a.s that of a sulphide mineral, when in the presence of both oil and water, will exhibit a preference for the oil. Ilciice the sulphide is not wetted. u'C'oncentratinc Ores liy Flotation.' Pape 99, Second Edition, i='Soai. nubbles.' By ('. V. Roys. Page 115. '■'Mr. Ingalls bas called it 'loncentration upside down;' Mr. Norris has called it a 'paradox.' THE KI.OTATION I'KOCESS 15 Tins clianictiTistic is less marked on the ])art of tlic heavy silicates, swell as rhodonite or parnet. and still less evident in the ease of the lighter silieious minerals, sueh ils ([iiartz and orthoelase.'* The addi- tion of acid lessens the oil atlaehinent to the fiiingne particles without decreasing the seleetiveness of the oil and the air for the sulphide particles. Thus we can undersUind why the huhliles attach tlienis«dves to the metallic parti(des and liuoy them to the top, while ignoring the ganguc particles, which sink to the bottom of the vessel in which the pulp is undergoing stirring or agitation. This preference of air for metals and metallic surfaces must he emphasized. It is the decisive factor in the process of flotation. Most minerals when pulverized, and then sprinkled on water, will float, particularly if they are in flakes or plates, as gold often is and as minerals with a highly developed cleavage usually are. Sueh flotation is due to air. which forms a dis- contiiuious fllm under the mineral particles. Mickle proved this by taking a magnetic mineral, like pyrrholite, and pulling it out of the water by a infignet, when it could be seen that the w iter was dragged up with the mineral. These minerals float for the same reason as an ungreased needle will float, namely, the resistance to rupture of the surface of the water and the aid of the air attached. It used to be supposed that the needle must be grea.sed in order that it may float. That idea, like the general exiiggeration of oil as a factor in flotation, has b(>en disproved In- experiment.* If. to water in which mineral dust is floating, an addition of alcohol or caustic soda be made, or even the vapor of alcohol be allowed to play on the surface of the water, the mineral particles will sink.'"' The con- tamination of the water has decreased its .surface tension. The bubbles collect the metallic particles, that is agreed: but whether the selection is dependent upon the previous oiling is a dis- puted point. Apparently the adb.esiveness of air for metallic surfaces is greater than that of oil. and it would appear probable that in the flotation process the first phenomenon suffices without the aid of the second. It used to be an accepted canon of flotation thnt the oil coated the metallic particles, which therefore were not 'wetted' and did not sir.k. while the gangue particles were not oiled and therefore were wetted, espcci j.iy in acidulated water, so that they sank. Testi- mony has been given by a keen observer that "the distribution of the "■'Tienriitir A. iMiikie. i-ioceeiiinKs oi" the Koyal bocletv of Victoria. Vol XXIV, part 2, 1911. *Spe pages 327 and 356 of this bool<. i-/&iVf IG ■rUF, FLOTATION I'ltOCESS Oil ill tilt' <'()ii('fiitriili; ami tlir Kaii'^iU' is rntiniy tortiiitous. "' ' It is uveii a'»erted now that instead of the oil nsidiiij,' with tln' niriailir liartii'lts cxc-liisivciy. and leavinn llic ^raii^ciu' i.iiloiU'iird, it is dis- triliutrd tliroii^liiiiil the iiiixtun'. When the larger proporlioiis of oil were cinployt'd. it is likely that siuii proiiiisciious oiliiii? of all tin' [(articles of the juilp did take plaee. hut now that the ipiaiitity has heeu ri'(luced to a jn-oportion so small that the jireseiiee of oil on the eoneentrate is not diseernihle hy the senses, we may assume a pii'i'.T- eiiee for the metallic particles in accordance with lahoratory ohsrrva tion. Tiiis appear.; to he contirmed hy i-xperiments showini; that in the case of speeilie minerals, such a.s chalcocite. it is nccfs.sary to oil the mineral in order to lift it hy an air Inihhle.'' Wlii'ii usinc; the, at i)iesent, minimum ciuantity of oil — say. one- third of a pound per ton of ore — it would a])i)ear that the oil forms a coatinjr of microscopic thinness upon the metallic pai'licles. The minimum thickness is the thi<'kness of a molecule.''' Metallic surfaces have a selective adhesion for air and for oil. as we have seen. Therefore the molecular forci's of the oil and of the metallic surface may he sujjposcd to unite in attractiiifj the hultliles. What the nature of those forces may he is yet a matter of I'onjecture. althoufrh the idea tiiat they arc electro-static is su-iiiested hy the fa.'t. amoiif; others, that the metallic sulphides most amenahle to flotation. are pood eonduetors of eh>ctrieity.'" The forefroiner statement of physical principles applii'S more par- ticularly to the frothiiift method. The history of the 'prior art.' as it is called in patent litifration, shows that the first stap:e of the flotation l)roeess as now in vopne was performed hy the use of a large propor- tion of thiek oil. This is typified hy the hulk-oil method of the P^lmore hrothers. It depends upon the lower specific jrravity of oil as compared with water, so that when mixed in a pulp of ernslied ore the oil rises to the top. dragprinfr the metallic sulphides with it. This also was explained formerly as due mainly to the selective adhesive- I'lBertram mount. teatifyiiiK for Minerals Separation in the Klniore appeal before the Privy Council. I niiRht aild that fortuitous' is a word that describes other things in the historv of notation besides the oiling. iTExperiments of B. H. Dosenbach in the Minerals Separation v. Miami suit, at Wilmington, 1915. is'Oil Films on Water and on Mercury.' iiy Henri Devaux. Mininij and Scientific Press. .Tuly 31. I'.uri. page l&K. H'The Electrical Theory of Flotation.' By Thomas M. Bains, Jr. Mininfj ami .^eicniiflc Press. November L'7 and December 11, 1915. See also page 225 of this book. Tin; ri.nT\TI()\ lH(i(t> i: ncs-s lit' nil \'-ealled skin-flotation methods of Hezekiah Bradford. Arthur P. 8. ^laeqnisten, and Henry E. Wood. In the first of these, invented in 1886. the pulp flows down an inclined plane OTitn flip nnipt smrfnpp nf irofpr in a vpccol or» tViat +li(i 1 lr^V»iHn ••1 par- ticles float forward under the impetus of their descent while the gangue particles sink. See Fig. 2. The explanation is that sulphides, by exposure to the atmosphere, attach films of air to themselves, so 18 TilK FLOTATION l'KO0E88 tlial they iiri' ikiI, wdli-il and iiiovc ovtr tin' wicallfd uattT skin, uliili- the gariK'i'', which hfis roiiiained wet tlirnuuhciiil tiic (ipiTaticiii. sinks throui^h Ihi' surrai'i' to tlie hottoni of the vessel. .Mai(|iiisten applied the siiiiie idea in a tiilie ea.st witii a helii'al j;roove and revolved at a moderate sjired. In l!i(l(i this method was (ho MiJM.I 2 atieen — Slisel 1 H. BRADFORD. METHOD OF SAVING FLOATINO MATLRHLS IN ORE SEPARATION. No 345,951. Patented July 20, 1886. ^Jnt-tnJit. Fig. 2. tiik bK.M)roiii) i'.\tknt. TIIK l-l,i>T\T|nN I'FfiiCKSS 1!) ailiipicd ill llic Adi'liiidc iiiili. al (ioliniiilii, X vjula. 'I'lic ore roii- taincd 2.29( '^oppcr as I'liah'npyiitc, with pyrrlidlitc and pyrili-, as well as sdiiic lilciidc and tfali-iia. Tlif naii(;in' was <|iiart/i)S(', (•(iiitain- in^^ si)in('l and (Lrariicf. 'I'lic tuhcs wen' id' cast in in. (i ft. Il)n^^, 1 I't. iiisidi' dianit'ttT, and cacli wci)»hfd 4r»() lli. Sii' Fijr. ■!. KxtcriiHlly Flo. 3. TIIK MAI yriSTEN TIBK. these tubes were cfst with two tires, whieh rested upon supporting rollers. The diseharge-end was entirely open. The feed-end was closed except for a hole in the eetitre large enough to admit the pipe through whieh the pulp entered. Inter- ally the tube was cast with a helical groove of :]-inch pitch, which was changed suhst>quently to li-inch pitch. The discharge-end was connected with a separating- box, the joint between tliis and the tube lieing water-tight, while the tube was free to revolve. At the side of the separating-box, directly opposite the discharge from the tube, an opening or lip was cut for the overflow of the surface layer of water, carrying the floating nuneral. This opening regulated the depth of water in the tube. The bottom of the opening was three inches above the inside bottom of the 20 Tin: FLOTATION I'ROCEPS tube, so that IIkto was llu'fc iiiclics (if water in tlic tiilic: tln' tVcd ami the diseiiarpe wen' s(i refrulated that the water pa.ssiiiji over tlie lip was about ,;', iiieii deej). The tube was rotated at -lO r.p.ni. in a direetidii corfespoiidinf.' with the iielix ot' the iiiti-rior. As Mr. Ttijralls said:'' "The l)ul|> is thus sen'wed tliroujxh the tulie and in its advauee is rejieatediy jjriveii an ('i)i>(irtunity ti> slide u])on the sui't'aee of the water, where it may be I'etained by surfai'<' tension." The ore was e>-u.'^lieiy, so that tile actual extraction was only (>:!'",'. Tlie inability to treat sliii e is a notable det'ect of this itip;eni(ni.s method (if flotatidn. AVood's methoil is e(|ually interesting. The ore is ernslK d dry to :iO or 40 mesh and is then fed in a thin strmim from a vibratiiia; plate onto the surface of water in a Ian'' to the surfaee of which a forward movement is given by small jets, also of water. By a eom- binalidii (if the capillary attraction and the pressure of a ediistant feed, the sidiihides are caused to move forward as a detinile elastic film on top of the water. This film of mineral jiasses over an endless canvas belt, which emerges from the tank at a particular angle, varied aceordiug to the kind of minei'ai to be saved. The belt with its tilin of sniphidis passes over three rollers sii that its motion is revei-sed when it strikes the water-level of a second tank, where it I'elcases its vahialle burden.'' Very little gangue in siisjiension eomes over, as the water drains 'laek into the main tank. Any submerged pjirticles that have been ai cidentally wetted or are so heavy that they have ]ieneti-ated the surface-film, pass to standard ciuicentration-taliles. on which they are separated by gravity in the (irdiuary way. In the case of nidiyhdenite and gi'aphite. the til^i cdMcentrate is still further cleaned by lieing passed (iv(>r a neai'ly vertical screen, (iangue in sus- pension passes tlnough. while the flat crystals of tlie valuahli> minerals slide over the sc"een. whicM largely dewaters them. The flotation con- centrate is collecteii and (lrie(l as usual. See Kitr. 4. Mr Wood is using his own jiroeess to eonuiiercial advantage in the treatment (if molvhdenite ore. at Denver. The ^rac(!uislen tube is ■'"The whole of the aliove description is taken from the adniiratile technical article liy W. I\. Ingalls in T'oncentration t'pside Hown.' F.iifj. <( Mill. Jour., ■ 'P'rom iiarticiiliiis siivcn to ni!> liy Mr, Wood himself. See also Trans. A. I. .M. E.. Vol. xi.iv (itui;), pp. i;s4-;iii. TriE FI.dTATION I'UOCESS 21 still ill usr at .Miilliiii. Idalio; Imt tlic Uracilnnl pati'iit is only of afail'iiiic interest. Tiicst' iiietiinds liavc liecii coiit'iist'd with the more recent flotation processes: tliey oupflit to lie (litlf'erentiatril. I siif?gpst therefore that tiny he classed under 'filin-siispension,' for it may lie i Fici. 4. IIIK WOOD MAllIINK. taken that in every case the sulphides arc cai'ricd with air over the tcnsional tiliii on the surface of the water. Incidentally, it may he well to point out that altlioii<;h it is con- venient to speak of the 'water-skin' and of skin-flotation,' the u.se of cither 'skin' or 'tilin' is inaccurate. .A skin is a thing of ili'tiiiite thickness, which therefore can be 'peeled' off. like the epidermis, for 22 Tin: I-l.i)TATION rUMCESS exainplf. 'I'lic iihi'iinineiini; of surt'iiri' tension iiivolvfs nothing of tho kind. It n fcrs to a comlilion of molcc-ulfir fori'es at the surface of a liquii!. till' ctVfrt ^ to li;i\i' 1h'i-ii I'c.l into H XTssi'l pr'ovidcd \\illi ;i luixiiii; drvicc. I'Uii iit it liiu'll speed, so iis to ii>ritate the ;ieidul;ili-d puljt. The sulphiih'S I'ose to tlie surtViee. nnieh in tlie siiiiie Wiiy as in tiie |)reeediii^ methods of Potter and Delpi'at. Tiiat of I'otter was useii, in a moditicd form, at the Hloek II mine at Hi'oi. 1 III iii.i.i liM' r\Ti r. THE i-LOTATION PROCESS luucess has heuii in use lor sevcnil years siULvs-snilly at tlie Bmk.'ii llill l'rn|,rirtar\ mii. . It is prup.-r t„ a.i,l, iK.uvvi'r.'tliat all of tlifsc aciii-riotatioii iiiptliods aro now only of academie interest. In the ciiiet applieation of these j)roi-esses it has not heen eiistoinary to use oil, but as the material treated came from old dumps of tailins? it may he assum.'d that th.'re was some sulistan.-e present .■ai)al)le of modifyin-r tile water sufficiently. ■" The first aj)i)lieation of any of the oil-tlotation proee.s.s(^s on a workini>l':elly. in Wales, hy Francis E. Elmore in 18!i!l. Tlie mi.xture of erushed ore and wafer was fed^^ at the up|)..r end of a .slowly revolv- ing drum. i)rovide.| with anindar helical ribs aiul transvers." blades, .so as to etTect the mixing' of the pulp and the oil without i)rodueinj? emulsification. See Fig. 7. The oil wa.s introduced fhrou5,'h a sep"- arale jjijic. The mixture was discharfred info a V-shaped vessel, where the water and sand subsided wliih. the oil huoycd the .sulphides to the top. An oil residuum liaviufr a speeific gravity of 0.89 wa.s used in e(inal parts hy weifrht with the ore. ton for ton. The oil was so viscous as to rc(iuire the aid of small rotary pumps to propel it for- ward^ The temperature of the oil and water was kept between 54° aiul r)7-F. The loss of oil was 2 gallons per ton of ore. A concen- tration of 14: 1 was achieved with a recovery (in the concentrate) of 6f>^; of the gold, G5% of the silver, and 70% of the copper from a I>yritic and chalcopyritie ore as.saying 1.12% copper, 0.04!) oz. gold, and 0.8 oz. silver per long ton. The process was described as "a somewhat dirty and nasty process." It did not work on oxidized or < I'thy ores, nor upon tarnishi'd sulphides. In the course of the discussion following the reading of the paper by Mr. Rolker from which these fact.s are gleaned, it was acknowl- edged that the process develope.l by Mr Elmore was ba.sed on pre- vious experimental work done, at tlie same mine, by George Robson, who used petroleum in even larger proportion, a.s much— T have been informed- ;is three tons of oil to one of ore. But the most interesting fact elicited by the discussion was the statement made hy ^Ir. Elmore, and confirmed by the .superintendent of the mill. John Bevan. that the ••'■This suKRcstion is ni.ele liy Mr Hoovpr in his l)ool<. On pape 101 hp says that "there may I;,, orwnic substances in the ore which, upon the addition of acid, yield gummy compounds that seiertivcly adhere to the 12;. •„•:;■ ::;:;■ :;;■ ;;r;::;r>:,iy riioarm ■oiiipiiuies,' liiiii is. ihe plenflp and Kalena. ■"Charles M. Rol] L':i \v;is iKil ihr iii\i-iitiir dl' ;i Wdi-kiiiLT |>riici>.s, iiil im liicnl thr iilia (it' violent airitiitioii for llir iiui,mi.sc of ])roiliiciiiir Imlil.lr-, <<( ijiis iMpidly from ii i)iiln coiifiiiniiii.' I"itli cilcitr and ai'id. Wliilc \w looked to i-ai-!;ou dioxide ;is llie i;as I'roiii wliieli lo make Ids Imlililes. lie did iin- douliteilly I'ntrain lots of air and olitained the nse of it in u'eneratinir III- llllMues lh;i| Jlllarlleil lllemselves lo lllr olleil Jiartleles. lie did not '■"•"I'l'ii' lid iiMii h oil : only -'a thin lay, ]■, " In Ids later insi lu.-tions to the Jlincrals Separation company. uIm.-Ii liomrlit his British patent in lll.12(), date.] May 2!t. IIMI,"). This is a i)roccss •■wherein, hy th(> u.s»> of a frothing; afjent, and in the pi-eseiiee of such airitatioii as will maintain or produce dis- trilnition of the ore [(articles tlironixh the pulp, and dis.spiinnation of liuhhies of air throufrh the pulp and into contact with the metallic particles throutrh the [(ulj). the air huhhlcs will seize Uie metallic particles and will carry them to and throuKh the surfaoo of the pulj). so as to iiermit of their delivery at or al)ove the surface of the ]Milp .sei)arate from the ^'an^ne [(articles." Tills description is taken from the complainant's liricf in the suit of Minerals Separation. Limited. r. Miami ('op]>er < 'om])any. liU.'). It is further explained that In this process "the frothing agent is an oil or immls of operation in the concentration of ores was attainahle with small qiianlities of oil. quantities so small that althougli the oil coated the metallic [larticles in the exercise of the well known preferential affinity of oils for metallic substances, the coating was so minute, so nearly Infinitesimal, that the oil disappeared from sight and sense. In this process the oil coats the metallic particles, modifies the water so as to produce inruite and pci-sistent air-lnihhles, and increases the attraction of the tallie ^larticles for the air- liulihles; and the persistency of the air-huhhies is such that the air- buhl)les ding to the metallie particles and carry them to and through the surface of the pulp, and when the air-hiihbles escape from their water environment in the body of the pulp and are expo.sed at or above the stirfaee of tlie pulp, their water-films caixying a mineral load are maint'iined intai't until at least their S(>paration from the body of the pulp has been effect(>d. by overflowing or otherwise. The air-l)ubbles with their mineral load form i' froth floatinsr upon the surface of the rilK KI.OTATIUN I'liOCKSS :il IMilp, whirli, it' allowfil to rniiuiii thc-r-r in ;i (|iiii'.sci'nt rdnilition will Hoal for ilays and weeks. This t'rotli lias tlierelnre lieeti pniperly called a i)efsist('iit i>r |)enniiiiciit frotli. It will always form a eoherciit mass >;t' liulililes pi'cssiil ai;aiiist eaoli other ami l're(iiieiitly several iiiehes ill thickness." This deserii)ti()ii, lackintr adequate piiiietiiatioii. as is usual in h'^al statements, may he accepted as otiicial, beiiisr the ])rodiict of a joint ef!"ort on the part of coiin.sel and experts representing' Minerals Sei)ara- tion in the lawsuit at Wilminjrton. In the basic patent, \o, S.{.").12(). tlie propoi-tion of oil is •riven as "a fraction of ]';; on the ore." ^V. H. Ballantyne. patent lawyer for Minerals Separation, testified, in the Hyde suit, that "an ideal standard for the afritation-froth proee.-js is Hto 2 11). oil per ton of ore." Mucli les,s is used now in the liin mills of the copper mining com])anies. The proces.s was first introduped on a working scale in the Central mill of the Sulphide Corporation, at Broken Hill, as already men- tioned. Two .veai-s later, in 1007, it was adojjted )iy the Zinc Corpora- tion, to he discarded during l'»Of) in favor of the Elmore vacinim process, and to ho restored again to favor in 1011. See Fig. 0. The next important application wa.s made in 1012 at the Hraden Copper mine, in Cliih', where a 200-ton plant was erected. The ex- traction of copper (as concentrate) was 80 to S.")';; . Hut when a larger mill of two GOO-ton units was Imilt the recovery hecame poor, lieing no better than it had been in the old water-concentration mill, namely, about 05';; . Whereupon the oil was added to the ore in the tube-mill and the extraction improved at once. The mill has now been enlarged to seven 600-ton units, treating o.jOO tons per day." The extraction last year was 77 per cent. In February lOlf) the Anaconda Copper ^Mining Company took a license from Minerals Separation, and at that time also the Tiisj)ira- tion Consolidated ('opper Company made an agreement for the same purpose. Roth companies built large mills for the operation of the process during last year."'' The Anaconda now treats 12000 tons and the Tnsj)iration 8000 tons of ore daily by flotation. The first mining company in America to ignore th(> Minerals Separation patents was the Butte & Superior, in Montana. Under the technical guidance of James M. Ilyde, this company built a loO-ton i ::t: xir:;;!";; a::::. .i::r;;My iJuCl :lM.l,..imp..ll,.,s-wa.s tn.'.l hrst a,„l then .lis.ani..,! a.s in.tr.rfiv... Tli. pneuniati. flotation I'iant at .Miami was con,,,,,.,,,...,! i„ Aii-iist 1!IH and n-modt'lrd in th- .ai-ly part of l!!]",. Suit for infrinK..m,.nt was lirou-ht at on,-,, hv .Arincrais Separation, the trial <-omiii..n,-insr on March 29 and ...idin'.r "11 -May L>.. 111]:.. Tim ,l,.,.isioii of the Court is not yet known. ..^Minerals Separanon. Mniited. and .Minerals Separation Ameriran S,vn(iii...ite. I,im:ted, r. .lame.s M. Hyde. rifi: ^ r.ur \iiuN I'liociss S.i \s apiiliiil at Miai'ii III.- fldtation [jhu'i'ss is siiniilili.il In the iisr of a laimil.r haviiiL' a raiiva.s iMilioin llinmu'li uliii'li ait- is toiv.wl iiiwliT imssi.n'. This ciM's tlir ".ms r.Miimvd for \\i,- i:rii.Tatioii ,,|' l,iilil,|,.s ill a pulp pn^vidiisly inn,|ilir,| |,y tlir a, This is tli,' part of thf .snltjcrt of which w<> liav li'ii'-d th.' most; ind.vd, until rcrently tho literature of the flotation process was closely idenlilie.l with the records of patent litif,Mtioii. That IS why tho scientitic i)rincii)les are as yet so little under- sto,,d and^the technolofry of the process lias made such scanty pro^'ress. The aim of a pati'ut spteifieation is to dis(dose just enough to prove originality. In many cases this has I n done to tlie apparent satisfactioi, of the E.xaminer of Patents without conveyinfr all the fai-ts es.sential to a dear uiiderst;ui,lin^' of the oi)erations involved. The description given in a modern patent is cryptic; it is couched in a 'jiiasidegal .jarg:)n that as'^ists ohfuscation. I refer to jiroces-scs only, for th<. disputes over flotation patents have arisen over methods not' machines. The apparatus required had already heen used in w..,er branches of wet metallurgy, so that we have heei: .si)ared one source of troulile. at least. The litigation, which is new ;i .serious ohstacle to ttie free develop- ment ,,f the jiroeess, has arisen largely from confusion of ideas as to the underiying causes of flotation. The patentees did not understan.; the phenomena with which they played. Those to whom they .sold tlieir patents knew ev „ l,..ss. Tl;,. inter]. retat ions of attorneys and judg.'S have elucidated the law hut c„nfused the physics, xi) clear Hd.iudi.'ation „f rights is possible so long ,,s claims and cminter-claims are ha.seil on an ignorance of the rationale of the process. As th.' flotation jirocess of today is es.sentially that of making a minoral-huoying froth in modified water, it is not necessary for im'to maie further reference to the patents granted for tlie use of purely surface. ten.sioii effects. It would serm pernii.ssihle also to omit further consideration ,,f the hulk-oil methods. Imt. as a matter of fact, none of the.se oi)erated withoul the aid of air. although the patentees were quite nimware of it. and it was from th.^s.^ hulk-oil methods that the frothing proci>ss was developed fortuitously. The first patent for the use of oily suhstances and .• lal-tar iiroilucfs in the concentration of ores was that granted to William Haynes. an Engiisiiman, in iStHi: iuit tins is now only of academic inferesf. Next comes the p;itenf of Carrie .1. Kverson. dated August 24, ]S,s(i. the TtlF. II,(iT\TI()N THdCKss 35 application having Ixrn tiled on Au!,'ust L'!t, 18Sri.-'" Thr Evcrsoii patent ret'ei-s to the seleetive aetioii of oil for "nietallie siihstances" and the inerease caused in that select iveness hy the addition of iicid. The pulp is stirred so as to hrinrr "the mineral" in contact with tiic oil and acid, producing,' a -'stirt' mass." The us(> of ■'iiliout ;i li.irnl of oil to the ton of ore" is mentionecl. indicjitinir a ratio of nliout 17'~;. Other statements indicate that she used as little as ")',' of oil |)er ton (,f ore. The sei>aration of the oiled mineral from the unoih'd i-'iuisjue is described thus: "In j)r!ictice, the concentrate, after thoroufrli afiilation of the mass iuid detachment of the sand, will in this case be preferably removed by meiiiis of a constiint overflow of wider from a washinsr-out ves.sel. I)y win li overflow tii. concentrate will be floated off." These la.st words constitute the only direct refcn'Mci' to the floating of the conecidrate. A great deal more has been read into this patent Ihiui could ever have been in the mind of the patentee. Tt is ditficult to ri'ad her de- s(>ription without cocking one eye at th" present practice of flotation, whereliy some of Mrs. Everson's phra.sing is given a significance to which it had no possibl.' claim 30 years ago. The proportion of oil used, even the maximum, would not sutTfice for the operation she had in mind, namely, the floating of the he;ivy sulphides by dii'cct aid of the buoyancy of oil. Iler maxinuim proportion of oil reiti-escnts a m(>re fraction of the (piantity re(|uired for this operation. She dis- closed no notion of the assistanci' to be obtained from air. in tiie form of bubbles, althousl'.. of course, tliis was her principal flotative agent. The process described by her is quite imiiraeticable on a large si-ale. and it never was operated .save in a crude experimi'ntal way. \ever- theless the exigencies of patent litigation have caused the opjionents of Jlinerals Separation to idealize both ilrs. Everwm and her metal- lurgical adventure, as they have also created a romantic story of the supposed epoch-making discovery. She is represented as a school- teacher, a Jliss Everson, who. as the sister of an assayer. washed some greasy ore-sa<'ks aiul s;iw the sulphides floating on the contaminated water. Even the idea of agitation was suggested by the activity of her hands in the wash-tub. Therefore "it only required the customary acuteness rf observation of the Western lnd,\' school-tenclier to grasp the es,senl al facts of sulphide flotation."-' This is pretty, but not scientific. The "essential facts" are a bit too slippery to be grasped iii]ruiuiui. «i3 ufiu^ lilt* one iruni which priorit.v of iiivpntion is nioasiired. 2i'Concentrating Ores by Flotation.' Page 5. 36 TIIK FI,nr\'IMN I'KciCESS liriiily cvni to,i;iy. In tliiiikiiiu' ari,| necessary, sli,. was wi-oi; It is lf air; tii.' int.'iiti.m was not t.i emulsify il il aii.i ii.it to a. 'rate tli.' pulp, hut this thi'or.'lii'al .'ondition was n.'ver fiillille.l, as is clear from th.' fa.'t that Ih.' flotative a.-ti.in was loO^; nmre than that .'ah'tilalil.' fnim th.' --Tn file i'i nntn inj Tr;}}-'.<^. V.::yrh ?. 10f:'^ -■''Tlie I'.'vei-'-on Mytli.' MitUnii nii 37 ditiVrcniT of spccitic firavily lictw.Tii tlu' oil and tlic water, On .Janu- ary :{. llili.i. A. Stanley Elmore took out a Hritisli ])at(nt for an aj)- paratus Jor excluding' tiic air dnrin^ the operation. He et^'ccted his purpose hy sealiuf,' all the open vessels witii a rinjr nr surla( f oil; from wiiieh it is evident thai at that time he and his brother en- deavored to base their method wholly on hulk-oil flotation. Ill January 1!)02, Charles V. Potter, an Australian, obtained a Uriti.sh j)atent for tiu' flotation of sulphides in a hot acid solution. He used a stirrer, and he claimed that the solution would '■react on the soluhle sulphides present to form huhhles of sulphuretted hydro- i.'en on the ore particles and thereliy raise them to the surface. ■-' In Novemher of the .sa-ue year. \'M)2. (luillauiiie I). Delprat. the mana^'cr of the Broken Hill I'roitrietary mine, applied f(u- a similar patent, except that he used salt-cake instead of sulpluiric acid. Liti- jration ensued, t'ollowed hy a eompronii.se. eliminating' Pott'r. fn later patents hotli Potter and Delprat introduceil the use of oil. finding it henetieial. In his first American patent. No. 7.i").n71. tiled on January 2. 100:!. Delprat states that the pn-css "depends upon the ore particdes heing attacked liy the ai'id to f.uiii a gas. Each ore particle so attacked will have a huh!ilt> or hul)l)les of gas adln I'iuir to it. hy means of which it will he floated and can I)o skimmed or floated off the Jution." ("Ore particles" means blende and galena at Broken .till.) Here is a pretty good recognition of bubhle-levitalion. only he sujiposed the sulphides, not the gangiie, to })e attacked hy the acid. Tii another |>lace he says specitically : "The sulphides in the ore are rapidly attacked hy the acid and gas bubbles formed on them, that (luieklv carry them to the surface." Tn this patent he claimed the use of nitric acid and a suitable nitrate, such as sodium nitrate, the latter being intended "to inerea.se the specific gravity of the bath." AVhat reaction was to follow between the sul])liides and thi' dilute niti'ic acid is not dear. It has lieen recorded-" that in the early days of the Potter Delprat methods it was suiipo.scd that the ai'id liberated hydro- gen sulphide from the sulphides, when s\di)huric acid wa.s used, with- out attacking the gangue. Those- who first scouted this idea suggested that cnrbon dioxide was generated by decomposition of a carbonate coating on the sulphides. (bu> to weathering of the ore, arguing there- from that it was necessary for the gas to be produced at the surface of -■"■The t'h.vsirs of Ore Flotation.' B.v .T. Swiiihiirnp and C. Ruilorf. Muiing and Scirntifir Press, February 24, 190G. 38 HE FLOTATION- I'ROCESS till- siilpliiclr particl. s themselves. All ot' tlieso expUiiiatioiis'" are now mi !li(> s.-rap-hrap of ilivanled tlicorifS. Tiiesc patents .a' I'niter and Helpfat liave lieen lalielled variiinsly fr^ O^erfhtv forConcentrate. 'jii "7 ieod BffflePlafe^. Pocket for^afthinq atones, bott^ ett. - Meta/ :ieat — ' Fn,. II). Tiih; I'oiiKK AI'r.viulL> luuler 'aei(l-Hi)tati()ir ami "sni-laee tension' nietlnuls. Uelprat's ap- paratus does indeed sugrgi'st a proeess ot' tli(> Rradford or Wood type, but, of course, l)otli he and I'otter depended for their results on the 2'In his book Mr. Hoover states (page 13, second edition) tliat Goyder & I^.iiigliton, in tlieir patent of ,Iiil,v 31, l!t03, "were the first to disolose the THE FI.OTaTION' PltOCESS 39 lilicratioii of ciulioM-dioxidt' gas I'rom the gangiio, wliicli, at Hrokeii Hill, foiitains a larso i)n)i)nrtion of (■arl)oiiatcs, iiotal)ly ealciti'. sid- erite, and rliodocrositc From any of those a hot sulpliiiric-ar'id sohi- tion would release the gas that proini)tly attaeheil itself t(, the iiietallii' surfaces of the galena and blende. -Meanwhih" Alcidr Fronient. in Italy, had -rot hold of the liuMih- idea, 'vhieh is the real ba.sis of the flotation process as it is understood today. He invented his method in IDOl and tiled his claim for a British pate.it on June 9, 1!)02. This patent was duplicated in Italy, but H'll in the United States. The fact last mentioned is important. Fnimeiit claimed that his process was '\a moditieation of what is known as the oil proces.s of ore concentration." meaning that of Elmore, for the hulk-oil method had been tried at the Traversella mile, in Italy, where Froment was engaged as an engineer. Ilis plan was to generate bubbles of gas by the reaction beiween sulphuric acid and the carbonates in the gangue, adding limestone when the ore did not contain enough carbonate. He argues that ''if a gas of anv kind is liberated in the mass, the bubbles of the gas become coated with an envelope of sulphides and thus rise readily to the surface of the Iiqui(' where they form a kind of metallic magma." It will be noted that he says "gas of anij lind." As the children say. in a familiar game, he was "very warm" .just th(>n. for he bad only to invoke the aid of air to havr described the es.sential principle of the later phase of flota- tion. He also states that the sulphide particles when "moistened by a fatty substance" have a tendency "to unite as spherules and to float upon the surface of the water." His brief description closes with the statement that "the rapidity of the formation of the spherules and their a.seension is in direct ratio to the qiiantity of gas produced in a given time." As to the oil. the only mention of quantity is made in describing a test-tube experiment in which he uses "a thin layer of oil," This phra.se has been variously interpreted, according to the exigencies of litigation, but it refers obviously lo a minute prop.irtion. principle governinK Potter's and Delprafs ncidflotation process, namely, that the action of the acid on the ore generated Kas-bubbles to which the sulphide particles attach themselves, and were ttoatod to the surface," What they said was that "the physico-chemical action develops the formation of g.is- bubbles adherins to particles of certain of the finel.\ 'livided minerals and causinc; such particles of certain minerals to rise to or near the surface of the solution." Rut tb!s i\c\c^ mt msV— *f ri^i^r th^t tv-..~. v.-.-.!,!. ;.-... ...... ..i.;..:...^.' by the deconiiwsition of the carbonates in the gansue; it is more nearly compatible with nelpiat s idea that they were generated by the action of the acid on the sulphides themselves. 40 TIIK FI.U'lAlluN I'KDCESS In tlic (lirtTtidiis ^'iv.ii liv liiin In ilir .Miiirmls S,|,iir:iti(iii pcnj)!,. when llifv ti(ai^'lit liis iiatrni ri<:lits mi Xdvciiilicr 17. l(Mt;i. Ii,. sin'cilii-d ]'; of niiiirral ciijuriiie-dil lor on- (•(iiitaiiiiii;.' up 1o ,')'; ot" iiiclal. 1 ', of oil for ore cohtaiiiin^' in',, ami so on. up to or'cs coHtaininir o^', of ni.'tallic lead, wliich woiiM rcipiii'c :!^'; of oil. .\s oil flotation was uiidcrstodd at that timr. this marked a irreat rciluetioii in the pro- portion of oil. However, the luoro iiitercstiiiir ])oint is Fron.ent's failure t(. jiereeive the possibility of usinp air as the tras for niakinix liis liuhliies. He <|.'pended upon eheiiii-al aetion to furnish him with the ne(e>sar.v >,'as. Xevertlieh^ss Fronienf desei'ves a liijrli i)laci' in the roll of flotation |)ioneers. for he made an important ste|) forward. He fui-nished the link lietween liulk-oil and air-froth flotation. Till' next elia|iter in the story marks a nt infrression. ("mler date of Xovendier L'.s, l!)(ii>, Arthur Iv ( 'atteriiiole ohtaiiied Hrii sli patents No. 2(k2!).') and Sfl.L'fKI. hdth i,f which were aeipiired hy John Ballot and associates in Dec'inher l!Mi2. preparatory to the formation of the company — Minerals Separation. Ltd.— orjranized to exploit them. In .\utrust IIMC! Cattermole revised and ami>liHe(l his jjrevious claims in I'-rilish iiatent No. iS.oS!!. which wa.s duplicated in the Cnited States under date of Septemlier 2S. lOn;!. as N'o. 777.27:5. This last is the principal j-atent eoverinjr flie so-eallcd jjrranulation i)roi-ess, ( 'attermole prefaces his ilescrii>tion hy refercnee to tlio seleetivene.ss of oil. when ennilsitied. feu- sulphide partiides. such selective action I'eini: intensified liy the acidnlation of the water. He IIkmi proceeds to say that if the mi.xture h.. tlinroufrhly asritated. there is a tendeney for the metallil'erous partiides. now coaled with oil. to adhere toirether. fornduu: ^'rainiles-^ ihat sink and are readily s.'parated from tiie licliter f'ans/ue liy an up-current of water. \u his deseription of the op. ration he .says that "the pnmules. with a certain amount of heavy sands, sink to the liottoin and aie disehartred [see Fipr. 11] throntrh a pipe (;' into the vessel A', whih' the lijrhter sands are carried away by the upward current and discharfied tliroutrh outlet (!- to a lifrht- sniuls taid< J." In the (lrawin''( of the weisjlit of metalliferi^us niiiieral matter l^rese!!* in tlio ore." This can be interpreted variously: if it refers to tlie sul- -sThe '«raniiles' nuiv he rnntr.-istid with Froniem's ■s|ilienilps.' THE KI.DTATION I'KOCKSS 41 phidi'S to 1)1' C'oiicciiti-iiti'il, llieii iiii oj JUtfi:: Fig. 11. THE CATTEBMOLE PATENT. 42 TlIK I-I.OTATIUN rUKCESS sorts of Viiriatioris in tcinpcnituiv. n.-iililirjitioii. oilm^r, ;,ii,l luixiiiK wnv tri.d l,y Artlnir H. ni^'j.'ins iimlrr diivctions from II. L. Suliiian Jiihl 11 K. K. I'i.anl. It was not iiii il ,Maivli ifKT), ilia' is, , .rally •2\ yrars sii!,;-fqu..i,t to the pati'Mtiiif; of the Cattonnol,' mr.liod. that it. was found advisable to float the -{.'ranulcs' .-atlirr than sink thmi, wluTvnpoii ensued ••||m- staitliufr discovery ,,f the airitation-frotli' l>ro(ess."' as \V. II. Haliantyne lias des.rilied it. A sinnhii iliseovery was made eontemporaneousiy at Hroken Hill, hut there, ac-onlinu' to James Ilehhard. it was not so "startliuir ;" it was the ivsidt oi' strenu- ous eir.irts to make a workable proeess out of the imi)ractieahle method devised liy C'attermole. Sot! Fip. 12 and 14. This 'diseovery' led to Minerals Separation's hasie jiatent T'. S. No. 835.120. of May 2!». im'). whieli duplieated the P.ritish patent \o. TSO:! of April 12. l!l(i.-), taken nut in the names of H. L. Sulman, II. V. K. Picard, and John Hallot. In this patent the aid of idiemieally- t'enerated fras is discarded definitely, in favor of airJmhhlcs. 'I'his .seems to me a matter of far jrreater importanep than the reduction in the proportion of oil. The patentees say: "It is to he understood that the oiijeet of usinj,' acid in the pulp aecordinjr to this invention is not to l.rinfr about tli.' froneration of ^'a,s for the purpose ,d" flotation thereby, and the proportion of neid used is insnflicient to eau.sc ehemic-al action in the metalliferous nnnerals prcstMit." This ditTeren- tiates the UK^thod from those of Potter. Delprat, Froment. and Do Bavay, the addition of acid beinsr therel'ore presumably to assist the .selective oiling' of the sulphides. The patentees also state that "a larf^o proportion of tlio mineral j. resent rises to the surface in the form of a froth or seum which has derived its power of flotation mainly from the inclusion of air-bubbles introduced into the mass by the a^'itation, such bubbles or air-films adhering,' only to the mineral particles which ar.' coated with oleic acid." The la.st clause had bettor have bd'n omitted, for it is only I'on.iecture, as to the truth of which there is room i:)r plenty of doubt, but the clear description of air as the main agront of flotation is most important— far more important as regards the rationale of 1h(> proccs.s, than the diminnti(ui in the proportion of oil. As to this, it is stated that if ilii' proportion of oil mentioned in the previous Cattormole patents "be considerably reduced— say to a fraction of 1^', on the ore— jrrannlation coa.s<>s to take ])laco. and after viporous a}ritj;ti:)n there is a tendency for a part of tlio oil- eoated metalliferous matter to rise to the surface of the pulp ii. the form of a froth or scum." One per eent on, ^ err is equal to 20 lb. THE FUJTATIUX I'lioCE.^S 43 of (lil ]>cr toil; ii •fiiictiiiii' (if 1', is iinylliini; lictweuii 20 iiml pounds per Ion. In fiil'oriinf,' tlii' ri-ilit to the roHcction of royalties, the Minerals Separation eoMi|)aiiy lias rested its claim mainly on the reduetiou of oil, (laiminf,' that it produces a series of piieiiomona quite different from any of tlie other methods em|)loyinir lartjer pro- portions of oil, and, concurrently, insistintr that such superior effects as are pro.iui'cd hy the use of the redneid i|uantity of oil are un- Ifo. 835,120. PATENTED NOV. 6, 1906. H. L. SOLMAN, H. T. KIRKPATRICK-i'ICARD i 1. BALLOT, ORE CONCENTRATION. ArrLiciTioi riLCt utm itoi ■ ■■IIT»-4IIIT I \ ^:^ ata^,^*. Fro. 12. THE CHIEF MINERALS SEPARATION PATENT. 44 TiiK KijirvridN I'iMCKss ohtaiiialtk' wlicii \hv lartrcr pi-Dpnrtions of nil aic uscil. TliiTtii[)(in, of roiu"S(', it lias liii'ii ilaiini'cl. Iiy tliosc (Irsiiiii^r to ijiiiorc tlic Minerals Sfjmratiori l)asic |)atciit, that iii'itln'r the ('attiTiiiolc nor tin' Froniciit iiu'tliodN ilcrnaiiilnl a c|iiiiiitit y of oil notalily lai'i.'i'i'. for the niiiiiiiia pnsi-rilx'd hy tlicsr carlirr iiivciitors coini' under 20 II). of oil per ton of orr. Iloui'vri-, this matter is still siih juilicf, so it is best let alone for the |ireseiit. Uetweeii the I'roiiient patent of 11102 and the Sulniaii I'icard Mallot i)at('iit of IIIO") comes the Kirliy i)atent V. S. Xo. SOU,!).')!) of 1)( iriiiher 14. l!to:i. irranted on -laiiuary Ki. lIHiti, This is interesting as spceifyinf' fjentle a^'itation and the use of a Ka.s, niakintr it possible to use thin oils instead of the viscous oils of the ])rior (Klmorc^ art. The claim is made that "the injection of ii air .is lli.- |.|iiiii. atfi'iit. 'i'lir i|..siTi|ili.>ii .iImi ivI'.ts tn 111.' imIi'.I iiii-taliUVn.us |.arti.'l. s as ••alta.'liiiitr \>< lliriiis..|\,-s. willi a irr.'al.T .•oiM|iarativi. si ri'iii.'t|] llian 111.. ■_'aiii.'u.. parti. -Irs, ||i,- lilms .ir f 873,686 FATENTED DEC. 10. 1907 D H NORRIS. APPARATUS iilR ^i r.ARAIIS.) THE MEIALLI ' PARIICLES OE QUi EKUM THE FOCKT CONSTITUENTS THEREOF. V -/:: /■/ iO tt }^dJU A -/ KlG. i;;. THE N0KR1> I'AlE.vr. 4« TIIK FLOTATION I'HOCESS lilllililrs III' <.MS whii-h I'Msl III III,' liiJi.ss ;inrr|iar((l iliis fsnlli ni (|i'scfi|)ti.iii of the lilllililc Irvilalinll nirlliud lliadi' "a starllllli,' (lisrii\r|-\ " d" |||r llnlll- iiiir pfiii-css fi;.'litrcii iiiiiiitli.s latiT. 'I'liis T. S. |palciit 7li.!.>^ns is iiinri' tliaii a y.^ar .jiiiiini- In l-'roiiirnt 's lliiiish palnil, aiiil i-oiitaiiis an c'-Iki 111' it in llii' iiil I'liilui'ldrv aiinciuiii'ciiicnl. Hliinirr's variiiiiii nil jirnriss inarknl aimtli' r inadvc rtnit slcji tuwai-ij till' ri'i'iiLrnitinn i>\' aii- as llir lMo^| iiiipnilaiit tlntativc aL'i'iil. lie iilili/rs llir air iialiirally <|iss(il\c'(| in uatir, r>li'aNiii'j: il Inr his piiiiM.M- iiiidrr a varinini 'I'lic patent stairs that ••iimlcr a variium I'l- partial \aiuiiiii, air nr t,Ms''s iIIssciIvimI in tlic milliner uati-r arc lilirrat.'d. TlicM' lilicraird ^'ascs may \ii- aui.'iiirnt.'d liy the ^'nicration i)l' trascs ill llh' pulp. Ill- liy iiitrndili-lioM trcnii an rxtcriial sniircr." HJiiKiri' iiivcnti-d .1 must iniri'iiiniis mai'liiin' t'nr liis piirpnsc. in so t'ar as lir ijipcndrd ni>nii tlir air in a pulp that had inidriL'niir mixiin,' with a ipiantily nl' oil I'i'lativfly small (as i'(iiii|)arcd with his hulk nil niithnd hi- t'lirnislii'd a notahic nii'talliir'.'ic sitrii-pnst. Init it is nci'cssary tn ri'iiH'iiilici' that he iiii\ccl his criisliril nrr in aridiilati'd uati'r and that the arid would raiisi' the frcncriitinn nl' i-arhon ilinxid- j;as, tlnis ('X[)lainin<,' his rrt'crt'iicc tn •"air nr trascs." Thr lirsl iiivriitnr tn lircak away t'rnin thf iisn nf I'ltlnr aiid or nil and In maki- a idcar claiiii for air as his snlr Hotativr a^riiit is Diidi.'y 11. Nnri'is, in !'. S. \o. St; l.^^oC, iindrr date nf XoviMiilicr l!t. lHf>7, alsn in Xn. ST.'!.. ')>;(;. nf DcTinlirr lit. llt()7. Scr Kii:. l:;. In his lirst pati'iit he dcscrilicil a iiicthod t'or "' intrndllriiit; watrr cnntaininj; air in soliitinn into the lower end of an opcn-fiidrd rcnptaclc into wliirh i>. iiitrmliiiTd a tlowiiiLr mixtiii'r nf jiulviT'i/fd ni' mixiMJ with nil and watrr, tliri-cliy cxpnsinsr saiil niixtiiri^ to thr rontimious artion of iiifniitesimally small na.scnt liiiMiJcs of air." He doi's nnt spcrify the iisr of ai-id anil hf ilistiiirtl>- says that lir docs not wish it tn he iiiidrr- stood that his iiiotliod "is limited to the use of oil. as the method can he practised sueeessfidly without iiiixiii",' oil with the pulvei-izeil nre and water.'" Incidentally, his iiicthnd is worthy of friendly interest, for he has dechir'd his intcntinn tn render the use of it free of tonnairo royalty.* Ifaviii'T got rid of acid and nil. we have now reached the i)oint whore modiliefl water mi.xcd with the crushod ore in the presence of air suffices tn form hiilihtcs .sutTfieicntlv lasting to huov th.fl iMof:!!!!'.' particles to the surf.ice of the liquid. *Spc page 274 of this tnioli TIIK I l.olAIION I'liiiCK.sS 47 Tin; I'.-\(iij. uiio, however, siin|dy carried forward the inetrective re- search of Kohson and Crowder, at tin' (Jiasdir iiiiiie. Tiie Kliiiores knew of the experiments made hy IJohwni. more particularly, for his simple apparatus was left on view at the mine when Francis Elmore and his lirother came there in iMtJ and I ame interested in fh.' prolilem. N'cxt there is the fact that in ] fact that in the course of a successful, hut niisleadinfr. test of the Potter method, the workmen in the Zinc Corporal ion'.s plant made it a jiractice to add luhricatintr oil to the liot-aeid solution in order to improve the result. This fad was not ascertained until .se ^ral yeais d'ter the test had heen tinished. At that time feeling, ran lii'' of July 21. Iitl4, It covers the same idea iis appears in T. .1. Hoover's Hritish patent No. 10,029 of 1010. I am informed that Mr. (allow was u!wiwai<' of Mr. Hoover's invention, which was not ]>at- I'uted in fills count r\ and is now the projw'r'v ,)[' the Minerals Se[)- aration company. However, priority of invention as regards this apparatus is a niatt"r of acatlemic inteirst oidy. R. S. Towne useper and the other Jackling companies made successful ai)pli- c.ition of the process by aid of their own research and persistent effort. Tp to 1011 the Minerals Separation metallurgists thought clialcocite could not be treated by flotation, ami said so. In ^Fr. Hyde's report of .January S. 101 1 . given as an exhibit by Minerals Separation i" t^ieir suit against Hyde, it is stated that the tests carried out in tile com- pany's London laboratory proved that "the copper ores of a good part of the Southwest and also of at least a portion of the Utah region contain clialcocite. winch is not tiontalile iiy any ot the methods so far tested.'' This opinion epitomizes the experience gained up to that THE FLOTATION PROCESS 48 liiiii' in llic Loiidoii liil"iiiitciiy. n»," '>■: tlir ]!tl4 cilitioii iil his Ijook. Mr. Hoovfi- mentioiis* the prcseiicp of l)nriiitf and i-lialcocitc as likely to limit the sueeessfiil operation of the process. It is now recognized that ehaleoeite is easier to float than pyrite. It is fair to add tliat, at 963,746. T. J. HOOVER. mUlTIIB rOB ORE COICEIT&ITIOI. irpLiciTioi THIS Mil. r. isoi. Pst«iot«d Apr 5, 1910. 'y-n I' U.. H. lilt. IHIIIM K .Ml'AKM' -^ r.ML.NT. •Page l!to, ('oiKentnuinj,' Ores liy Flotatio I 50 Tin; FLOTATION I'KOCK? a later date, one or two important copper eoinpaiiies obtained an in- creased revenue tlianks to tlie i>isistenpe of Minerals Separation in reeoinmeudinf;^ the use of their method. This insistence resulted in valuable eontraets. It is well to warn the reader against the inferences attemi)ted to he made from experiments in court, or elsewhere, intended to prove that sundry effects can he obtained or cannot be obtained by following:? the descriiitions in various patents. As a matter of fact the results depend largely ujKtn the manipulation, performed usually by an operator who knows a great deal that w an excessive royalty acc\iously they had re- porti'd that the ore was unsuitable to flotation. Some of the com- })anics that ai'c now operaiiiig suceessfnlly went (irst to Minerals Sei)aration for giiidane,. and obtained so little a.s,sisfance that thev tWho li;is tolil us .-iboiit tlie maidens ilwplliiif,' ii|ion a ni.vsteiious islaiui on wh!'.'!i ihvv their fratliers in tlie iiitcli. iuiil flien iirncpe.led to aiiotlief lake wlieie they extracted cold trciiii the sand liy Irniliiii; their iiiieliy featliers. THE FLOTATION PR0CES8 51 hiid to solve their own ditifioulties for thcniselvos. One or two big eonipatiies iiave won reasonal)le terms; for instance, it has been dis- closed that the Anaconda and Inspiration companies have guaranteed that if tiie Supreme Court reverses the Hyde case, or if they do not exercise tiieir option to surrender their license in case of afitirmance, tliey will treat 25,000,000 tons of ore by the Minerals Separation mctiiod by 102;}, and will pay the agreed royalty thereon, this royalty beini? ji ciMit per pound of copper, but not less than 12 cents per ton of ore; and meanwhile, whatever the decision of the Supreme Court, they have agreed to i)ay a royalty of !f;:J0O.0O0 to Jlinerals Separation within a year from date — nine months ago. Having regard to the fact that the extraction by flotation, as compared with ordinary water concentration has been improved from G.j to 95%, at no greater cost in i)lant or of operation, it is obvious that the copper companies can well afford to pay such a royalty, if the improveiucnt is due to the use of patents owned by Slinerals Separation. That point the Su- preme Court will decide at an early date. But. as I have said, it is not the amount of the royalty but the method of levying tax and the attempt to place an embargo on all information concerning the technique of the process that has aroused opposition. The type of contract made with licensees has caused many operators to refuse to come to terms; but the more objection- able practice lia.s been the enforcement of binding contracts on the metallurgi.sts employed by the licensees, such contracts being legally invalid and representing an attempt to liluff the profes.sion.''^ For the most i)art. until quite recently, the information available on the flotation proces.s has come from patentees, their friend.s. and their enemies; a good many of the facts available have been elicited in the cours(> of litigation, which has now been in progress for ten years; tlierefore a vast amount of non-science has been mixed with the little .science that has survived amid thoroughly uncongenial .sur- roundings. Anybody familiar witli the bitter busiii(>s.s feuds and per- sonal vendettas generated during the course of quarrels over patent rights needs not to be told tliat keen prejudice, amounting in some cases to malice, has iieen injected into tlie ragged literature of flota- tion. The \var|>ihg of scientidi' vision is astounding to the detachi'd observer. Much that has got into print and inori' tiiat has escaped a permanent record has been written with a jaundiced eye on tiie law- courts On t(in of tlii>; \)u> iM,.t:illni-in- ,^t' tl... oi,h;.>,.t l,..o I.,,,,.. .^1.,.,.,.I •-■Minerals ;Se|iiiration Contrarts with Mctallursists.' Miiiinii and .s'ric»- tiflc PrrsK. Feljniar.v 5. I'Jlfi. Also 'A Professional Matter,' In ttie same issue. 52 THE KI.OTATION I'KOCKSS miller an tiiiliiirfr(» of scfircy liy the owiicrs of tlif cliicf patents, and this lias 1)0011 oflFootivi to the extont of provoiitinp tlio technical men in the employ of the process-monerers from contrihutinp to curiciit knowledge. Only recently has there been any considorahle r.mtrilin- tion from independent sources of information. Another important element in retarding the technology of the liroce.ss is the ignoring of the fact that it depends far more on physical than on chemical considerations. To the physicist, not the ehemist. wc must look for guidance. The metallurgist hitlierto has depended ujioii chemistry to guide him: he must now go hack to school and ae(|uirc something more than a smattering of physics, if he expects to understand the problems of the new process. To most of ur; chemistry conies more easily because it has a sign language, that of the formula, to convey ideas, while physics depends ';'~oii the use of terms, half of which bog the fiuestion. Hence the stiuu nt must begin by rejeeting the use of terms that !;o docs not understand and when he has learned to understand tiiem ho must take pains to define them Avhencver he u:idertakes to convoy his ideas to others. By such sin- cerity of thought it will be possible to make real progre.s.s. and to apply seienie to industry with results far Iranseeiiding any hitherto achicvod in this field of human activity. KI.(JT.VTI0.V TESTS AT MOINT MUK(JA\ '>:\ , FLOTATION TESTS AT MOUNT MORGAN By William ^roTiiER\VEi-L ( (•"roiii tlif MniMi'i and Scieiitific Prrs.s of June 27, I'JU) The .Aloiiiit Morgan gold mine in Queensland, Au.stralia. which was disi-oveivd alioiit ISO years ajjo, is Relieved to he the richest indivitlnal gold mine ever found, having produced over $70,000,000 worth oi gold to date, besides copper. In its early stage, the ore, which carried hundreds of ounces to the ton, was cnislied with stamps and amalgamated, but the recovery was not especially good. Subsequently, and until seven years ago. all the ore was dry-crushed in ))all-mills, roa.stcd. and leached with chlorine solution in open lirick vats and the gold precipitated on charcoal. At that time the copper content of the ore was negligible. This is our of the few large gold mines in the world that never had a cyanide plant. About eight years ago, a large body of rather silicious cupriferous sulphide ore was found in the mine. Blast-funiaces were erected, and the less silicious ore, which contained about $10 gold, -1% capper, and 45% silica, was, and still is. being smelted. The more silicious or so-called 'mundic' ore, carr>-ing about $15 gold and 1% copper, was then dry-crushed, roasted, leached with sulphuric acid, the copper being precipitated on scrap-iron, subsequently l-^ached in the same vats with chlorine solution, and gold precipitated as before mentioned. About 1« im)nths ago the gold content of this 'mundic' ore began to decrease, and the copper content to increase. For this and other reasons it was deemed advisable to cease this method of treatment, and the last of the chlorination works was shut down. It now b.caiiie necessary to tind a protitaMe method of handling this cla.ss of ore. As iron-bearing flux has to be brought a long distance, and as the ore carries about 70% of insoluble, smelting would be too expensive. Tliere is believed to be at lea.st 2,.")00.000 tons* of this cla.ss of ore in the miiir. a.ssaying roughly $0 gold and 2% copper. This is in addition to th.> so-call.d 'copper ore' which is l>eing smelted. It may be explained that there is no 'carbonate zone' in this mine. All the copper is in the form of chalcopyrite. The gdbl is verv' fine. A few years ago some experiments were made by (Tushing in •Thf long ton, 2240 lb., is used throughout this article. 54 THE Fr.oTATION I'liOCKSS ball-iiiills and uoiu'fiiti-Mtin^' cm WilHcy tal)lis, hut they wcru not succcssriil. [,a.st year it \v;is tliMidcil tii make a tliorou^'li trial of the .Minerals Separation imness. and a small testing plant was ereeted in tile lalioratory. At the same time a full-sized experimental unit, ca[>alile of treatinfj :{()() to 4(l() tons jter 24 hours, was ereany. After they were finished, a representative of the Australian braneb of Minerals Separation. Ltd., paid a visit to the nune and eondueted a few tests, wliieh eonfirmed the results olitained by the mine stafT. As mentioned in the Company's annual ie|)ort, thes(> tlolation experiments were sueeessful. the extraetinn lieinfr hifrher and the costs lower than expect(>d. The company is now buildinj,' the first unit of a plant to treat 1000 tons per L'4 hours. The ore will be cru.shed by roek-breakers. Symons disc erushers. rolls, and tube-mills. It will thi-n be eoneentrated on Wiltley tabb's. after which it will po throutrh a second set of tube-mills, thence to the flotation machines. It is i)resuiiied that no royalty will be payable on the ^Vilfley coni-ciili-ate. This concentrate will eitlni- be bri(|nettc(i or sintered in a Dwiprht-Lloyd machine, and smelted in blast-furnaees alonj; with the 'I'opper ore' and ii-onstonc and limestone fluxes. The Compan.v has no reverberatinnr fnrnnces. Al'I'l.If ATIii.V OF Fl.dT ATId.V Til (iol.I) (tUK A flotation i)lant is beinin(j u.sed suci'cssfnily to treat ore containintr an ajipieeialile anmunt of frold. The KImore ♦ hick oil i)rocess was installed at the Lake View Consols trold mine, Kaljiroorlie. .several years ajro. but was not successful, as the ore was not suitable, and unsuccessful experiments wei-e made by Minerals Separation. Ltd.. on ore from the Lancetield nunc. Western Australia, which contains mispicke]. The Elmore vacuum i)ro.'ess was installed at the Cobar iSn\,\ mines, Xew South Wales, and at the New Havens- wood ^'old mines. Queensland. I'.otli these mines contain coi)per in the form of sulphide. ,-is v. '11 as f.'old. but tiie plants only ran a few Weeks. I was informed thai the pbiiit at the former mine (where iiie (Uf ciiiiiaiiis aiiipui .>S truid ami "[.■■ , cojiper ^ ^avi' a fair recovery of co])|K'r. but left too much irold in the tailin c\i)criincn1al mill api)roxiiiiatc clost'ly those obtained in the hilioratory. The ol).iect of concentration was, of course, to obtain a concentrate containing as much gohl, copper, and iron, and a.s little silica ns ])ossible. coirniiensurate witli a pood extraction of the f,'nl,l. b.vaiis.- it was found that the less silica the concentrate contained the poorer was the extraction of pold. It costs l.i cents to flux one unit of silica, and it was neces.sary to steer a middle course. Kxperiinents ma(h- with Sonstadt solution on ore from one part of the mine showed that clean quartz (after separation by si)ecifl( srravity from all mineral > c()ntaineonitory plant was at first run at 1100 r.p.m.. l)ut was afterward reduced to 800. Tests were made with I>ulj)s of different proportions, each separate pulp being agitated for the .same length of time, that is, (i minutes, and it was found that there was not nnich difference, in the extraction of gold and copper, between a pidp containing three parts solution to one of ore, and a ])ulp containing seven i)arts solution to oni- of ore. A pulp of 1 to 1 was too thick and gave poor results. In practice, the thinner the pulp the smaller the capacity of the flotation machine. Tests wc^re also )nade to a.scertain the effect of agitating for different lengths of time. Two tests were made in the laboratory of which I have a note: one for 10 mitnites and one for 1.') minutes. The ore contained .^0.50 gold and 2^,' .'opper : 12^,' of this .sample would remain on a (iO-mesh .screen. The first one gave a concentrate containing $22.70. t).4f-,' copper, and 18^; insoluble, with an extrac- tion of 51';; of the gold and 84.5^; of copper. The second gave a concentrate containing .■i<20.20 gold. 7.8' ; copper. ;ind 27',' insoluble, with an extraction of 04..")'-; of ir„]d and 01 S^; copper. The gold left in the tailing was probably in the gangii. . as the extraction was poorer than usual. As a rule, the longer agitation and separation are continued, the more silicions the concentrate is. In practice, the length of treatment is regulated by the thickness of pulp and the number of boxes in the flotation ma<-liine. Tests made to ascer- tain to what degree tine cnishing was necessary .showed emphatically iiiai iiic ore nuist aii pa.ss tiirougli a scrci-n of (id jioles to the linear inch if a good extraction is to lie obtained, and that the finer it was crushed, nt any rate down to 120-mesh. the better the extraction '^'' 56 TlIK I'l.OTA'ridN I'ltoCKSS \v;t.s. Tests sliDWi'il lliat uiicii usiiii; I'Ucalyptus nil tlifi'i- \\a.s H'l advaiitnjie in iisin^ iiii aciil soliilidii. Init tliat, on tlic otlin- liand. slifjlit acidity did no liariii. Miicii of tlic co|»[)i'i' |>yrite in the ori> readily floats on water witliout any |)re\ious ajiilation. On treating ore contaiiuiifj $1'.") trold direct liy a!.'itation ancl tlotalion. without anifdgainating or concentratinK on tables, it was ])roved that fine free gold can lie Hoated liy usinir eucalyptus oil. rsi;nti\i. Oh.s -Many oils were testeas fo;ind to give a better extraction of both gold and eoi>per than any of the individual oils, and at less expense. When the samjtle was all cnislied to pass SO mesh, an extraction of 80^ of tlie gold and !)0^r of the co]iper coidd be ol)tained every time, with a concentrate containing about 2n% insoluble, which can be reduced to 10% hy re-treatment. Hot solu- tions anr linear inch, containing $:!7 gold and 4.8% copper, gave a recovery liy flotation alone of OO^c of the gold and !)8.r)%i of the copper, but left ."iiS gold in the tailing. The concentrate carried 44%) in.soluble matter, which could l)e reduced by re-treatment. A different oil ( eucalyptus! would have given a poorer recovery and a cleaner concentrate. Tests made on ore containing $9 gold, 3.5% copper, and 45% insoluble, showed that after crushing to pass 60 mesh and treating bv direct flotation, an extraction of 82'~; of the gold and Wy'", of I'l.oTATlUN TL^-'IS W MKIN T MdKii \N 57 i llif (-(ipptr iMinlil 111' ol.taiiiiii, witli a (•(.iicciilratu udiitaiiiiii!,' uiily L'l', iiiMilulilr. N,) (l.iiilit with liiiiT cnisliiii!,' t'Vfii lii'ttiT recoverii-s would lie liail. Tlicsc results Iravi- fabl.'s and vanncrs far hehiiid. It was found decidtHily advantageous to re-use the solutions. A Wilticy talilf was tTccti'd in llic mill, some tests made, and the tailing treated jpy Hotation in the laboratory. Sometimes these tailintr .samples were dried before flotation, and sometimes they were not. It was invariably found tiiat a better e.\tra''tion was obtained from those whieb had not been dried, as no matter how carefully the operation wa« conducted, some of the iron pyrite got suliliciently o.xidized to resist flotation, and it carried some of the gold. In some of the tests the crushed ore was concentrated by paruiing in the laboratory, and afterward subjected to flotation. In this case the water in the laboratory was used, which did not com.' from the same source as the water used in the mill. It was noticed that the longer the .siimple was allowed to remain in the water after panning, the worse the subsequent flotation was. For example, where flotation took place immediately after vanning, the residue assayed .'i;2.G0 gold and 0..'5(K;; copper, but where tailing from panning was allowed to remain under water for 6 hours before flotation, the residue assayed $3.10 gold and 0,67% copper. .\n analysis of this water was made, and this incident shows what might happen in a mill where the ore is in ccntact with bad water for .some hours before reaching the flotation machine, sueli as the time it is going through rolls, Chi!(>an mills, tube-mills, and ela.ssitiers. over tables and through thickening devices, and perhaps through secondary tube-mills. The water in question was neutral, botli before and after coming in contact with the ore. Some tests were made both in mill and laboratory in which fiir was drawn into the agitation bo.xes through pipes fixed vertically in the corner with the top open to the air and the bottom ending in a lieiit pipe terminating under the impeller of the agitator. No improvement was. however, noticeable. Grading tests were conducted on crude ore and flotation iiroduels. Tlitv showed that a.s regards crude ore. after crushing either in mill .ir laboratory, the finest grade of concentrate or nre was the richest and the coarsest grade of tailing was ricln st. both in gold and copper. The fact that the finest grade of tailing was the poorest shows that tiiis prore.s.^; uiii noar the iiiiesi suipiudes suei'essfuliy. rRl'SHING Pli.\NT In the experimental mill the ore is crushed m rock-breakers and 58 Tin; ri.uT\ri(iN ruocKss Kni])i) (li'ViTUsliiii!^' Iiiill-iiiills witlmut dniiij.'. 'I'lii'^ plant was I'oriiifrly iisnl in mish uxidi/iil days with a consumption of 2 II). of cyimide. Samples of slime were treated l)y atritation and washed l)y doeantation, and pave sli^/.itly better extractions, hut tiie cons imp- tion of cyanide went up to (J or 7 Ih. The strensrth of solution used in these tests was OAO'', KCX. It should perhaps he noted that all samples of flotation tailini,' had heen dried hefore heiii>? tested by eyanidaf ion. KkFKCT OP HOASTINli Two samples of sand from tailing were roasted and treated by percolation. The value was $:i. The roasting reduced the sulphur to 0.5%. Although the copper and iron were oxidized by roasting, the eonsui'iption of KCX was less than in treating the unroasted tailing, which was contrary to expectation. With three days treat- ment, the residue was reduced to $1 per ton, and about one-third pound of copper was dissolved from each ton of tailing by the cyanide. The consumption of cyanide was 1.4 lb. per ton, so that the extraction was Insrher and the loss of cyanide less than in treating unroasted tailing. Speaking from memory, I think that attempts to regenerate the cyanide in solution by means of sulphuric acid and lime were not very successful. The sf)lution contained 0,05 gram copper per litre. These c.vaniding tests were mert^ly done for information, as it is not exjiectcd that the tailing from tii new mill will be profitable for cyaniding. The subject of extracting gold from flot.ition tailing arose a few years ago at the C'obar gold mines, as already mentioned, but in Ihal caw (he diniculty was overcome by selling the mine, which contained highly silicious ore. to a company which owned a .smelter, and had, or thouglit it had, plenty of basic ore for flux. T'nfortunatel.v, the amount had beeti overestimated and the problem IS sliii uii.soiveii — o'lit tiirti is anotncT Siory. eo THE FLOTATION PROCESS OILS USED IN THE FLOTATION PROCESS Uy An OccA^iuNAi, ('(induui iciu I I'loiii llii' Miiiiicj iin'i Sfiiiitifii I'liss ol May 1. i;il.')i I I i,'i iiM I iiiin . Tlir «iirkip|' lit. |)ii.st twii _\ I iirs ill iii,iii> mill- iii tlir 1 rillcil Slillo. Mi'M.Mi. ;i||i| S.illlh A IIH'l iiM . llilS lliili.- .iiiiili In |ini\r llii- siiitali:lit \ I'l tlotati'Ui iirnn^scs tn tjn' riToviTv "I tlir miI |i|ii(|i' (•r(> ol' ciipiiiT. iiinl III iiiilii'ali' till' lirsi iTaL'rnls, In a irriitral way. It iiiav lie (anl llial uiIn ol' luiiural iiri|.'iii, m|i-Ii as mal tar ami I'llrl ml. i,'l\r lirtlrl- M'-UJK (ill rnllli.T ofcs. wllill' nils (iT \i '_'' lal nli'-'ill, SUi-ll as till' ti'l'lirlh s. |iih''ncs, WimmI tars, cti'., arr iirttrr ,ii|a|ili'.| for tln' troi!tiin-n1 dt' /iur ami liad oit's. (''i\i..T\K I'liui)! I r-. Aiiioiiir tlirsr cri'sylir and cai'lmli' ai-ids are tlif lirsi kiiiiwn ri'ai;<'iits. ( '(uiiiiH'rcial crcs.vlic acid is an nily rrl'rac- livr liijiiid. jTriiirally with a ml nr y-'llow lin^'i', lias a s|irciiif L'ra\ity III' aliiiu'; l.(i44. and nmsists i>\' a|iiiriixiiiiatcly 4"', nn'tai-rcsylir. .!.")',' cii-tliiii-ri's.\ 111', and -'>'', ]iarai-i'rsylir arids, the pnipcrtirs nt' tlioso tluvf isiiiiiers lii'intr, ai-rmilinix tn Lunsrc and Kraiif:' Solubility in 100 parts water, ordl- Acii!. R 1'. nary tcni|ieratiire. Orthocrfsyli, IHI ' 2.J0 vol. Metacresvlii 20;; ' 0.3?, • I'ar.icn-s-lir 2ii2' l.SO " 'I'liis ai-iil is iiiurli Irss snlulilr in wati'i' than its hmunlnunr. lai'lmlit; arid, and is still iimrr rasily lirnkrn ilnwu hy siiliiliurir. whirii iirnlialil.\' ai-i'i>unts fnr the stidriiinit that siilphnrir arid may not he iisid almii; with t'ithi'i lit' these weaker aeids. .My own exj)eriiiieiit.s trivi' i onriiet- iiitr results ,ind I ( aiinot sjieak with rniilidenee on this point. 1 liavi- |o\iiiil a marked dit1'ei-enee in the liehavior nl' diil'ereiit lirands oT eresylie aeid, and I siiLrirest that, in eonjiii-.etinn with test.s run. the dilVereiit ln-aiiiU he aiialx/ed to see what liearine the ditl'er- in^ aiumint of the three ennstitiieuts has on the action of the various aeids I had vei'y pnni' siieeess ill treatiiij; a eertain e'.iale.ieite ore with a dark enlnreil eresylie aeid. and on eliani.'inir over to a liL'li! 'iiliiii.,! Iirand. I had itiiiiiediately suri)risin<_'ly trood I'esults. LuiiL;e and Keane fjive a method (" IiaselieKli IN ^M^. 1 IDIKTIIIN I l(()(h>S »;i < >M iKJllill^' //I 1 IT.SIll Willi i\rr>,S clI IINO . ill I'MI ll l^ .|llillll|lM ti\cl> (Diivcrtcil iiitii triiiilriKTiMpl. wliilc if-, iMimcis mr > m-miIi triy oxidi/i'd to OAalii; aciii. Tlif 'nllowinj; ilirt'ctiiniN, wliirli must lie iiiiist .urcl'iilly (ilisiTvi'd, y,i\r rrlialili' I'fsiilts; Mxa'ily In v'i';iiuiii>'s el' I 111- ( tcndI iiiixtuii' ;iir Wciirlird iato ii siii.ill cunii-al fl;i.sk mixed with 1') (■.,■ iirdiiiaiy ll^S(), il.N4 , then ticatcd tor 1 lidiir m a stiaiii (i\(ii. and the ((Piit-'iits |)oiirtd into a w idc-iiickid Hask "I' 1 litVf (•a|iai-ity. 'I'hc tlask is ciHili'd iiihIit tlif laji, sliakiiiir it I'nuiid mean vvliilc in siii'li a inanner tiiat tlic siilplionii' a<'ic|. wlii(di is a nmliilr li(liiid w iiilc lint, settles as a tliiuk Nvnip un the sides nl' liie Hask diii'iiitr eiHijlllir. 'H» e.". dl' IIN'O il.!!N' ai'i' tlieri ti|-st |i(ilireil into tile small tlask ill wliieli tile siil|p|ioiiatinii was rniidiic-ted. in urder tn I'eiimve any siil|ilmiiie arid adliermi; tu iis sides, i' ,ed well niiind, and tlieii jinured. all at miei', into tlie lartrer tla.sk. The ennleiits nt' the lailer are Well shaken iiiiiiiediately. so that all the sulphonie acid is dis- s(p|\i'd. wlii"li takes ahullt iJn seemids. The tlask is then plaied in ii draiitrlit eu|)lM>artl. After one ininiitf a violent reaction occuis. it'.l I'llliies are evolved, and the li(illid hoils: then it suddenly liecomes tiirliid; oily dro|)s ot' trinitroeresol I'oi'iii and eolii-t on the liottom lit' the Hask ; and alter five iiiimites tli. rea'tion is appareiitlv ended. The whole is allowed to stand for at least another ti\e ininiites. then poured into a dish eontainiii^' 4n c.e. water and llie tlask rinsed out with a further 40 e.c. water into the same dish. On luixintr wiiU water the trii.it ro-//i-cresol solidilies with liheration of nitrous fumes to a crystalline ma^xma. It is allowed to stand for at least two hours while the liquiil cools: then it is crushed with a p«'Stle and filtered on the jjuiiip tliroii^'h a tiller that has heeii ii red against another one. The crystals of trinitroeresol are washed with 10 c.e. U/), dried at li.'i to 100" and weifjhed. If these instructions r.re earefiilly followed. 1.74 trin. of trinitro-/yi-cresiil are ohtaiiied for eaeli frraiiime of mefacrcsul [iresent in tlie mixture whatever the coinposition of the latter. The presence of even 10',' plieii(d does not diminish the accuracy, as the picric ai'id that is formed remains in solution, liuf the iiiefliod must not lie applied to iiiixtiires coiitainiiisr lar^re aiiiounts of ])lieiioI. This, however, does not often occur in practice. In such Siiiiiples the presence of plienol is detected by the H.!'. and also hy the fact that the nitro compound does not reininn solid in the sfeam-oven at '.C> to 100 '. hut melts, or. at aii.v rate, forms a s:d't pastt . Rut a cresol tl'.--if .-I'.ufili; i'c.r H-.ii T^'.;-.-l T-.;:rf tv^if •.•.•i;;iT-. VIO -.;i...-l '(10.- n:-..! i!;,i-.-. *'..-.-.. contains scarcely nny plienol. always yields a pale yellow crystalline mass, the wcifrlit of which divided by 1.74 >;ives the weight to within 62 Tin-; 1 i.olATliiN I'HOCKS-; 1', of tlif //i-crrsdl ill the iiiixliirc. It iii;i\- lir well to i.'piiil llwit not less than '.tO v.^'. of IIXO,.. is iisi'il, niid pinirod all at oiici' into tin- rtask as (iiiii-kl\- as possible, a Hask having a very wide neck liein^' used. To d<'li'niiiiic all tlirec isonieis liasrjic;: sejiaratrs tliu (/-i-rcsol coni- lilrtcl\- i>y n'lxatcd Iradional distillation; the distillates lieiiif,' i- posed i-oUL'lily of (in'( //(■ and 40' ^ /(-eresol in wliieli the f/i-iresol is di'iei-iiiiiied as above. This ojxTation. however, is entirely beyond the skill and resource of the avera^'e ehrmist. It is renilereil uniK ssai-y from the fact that the three ai'ids iii"ntioned bear a fairly • instant ratio, as before stated, in any eoimiiei'cial eresylie aeid ; from tlie pei-ccnla^'e of lurta-eresylie aeid formed, the others may be ealeii- lated. These- three aeids ean be olitained in a iinre state, 1 sufj^est a trial of them on a small scale, and 1 venture the ojiiiiion here that the ortlio (-resylic acid is die one that does the work. Cresylic acid should be handled carefully, as it jrives rise to painful skin-wounds, and may easily spla.sh into the operator's eyes. It is well to keep a bottle of olive-oil hands as a r-'iiiedy. 'v'u.vi.-T.MJ CuiXj .s, — Cresylie acid is an expensive ri'ajjent, eost at lea.st .tl.1'5 i>er pi'lm delivered at Western American mills in j)eace-time. It comes |ii'incipally from (iermany and En^dand. A search for a cheaper substitute has shown that crude coal-tar creosote. whi(di is a by-jiroduct of j?as-work.s. bla.st-furnaces. and s^as-produeers, is |iroiiiisiii^'. Samples from ditl'crent sources vai'y irreatly in liipiidity and (diemical com]iosition ' nroiiortion of jiheiiols and cresols ]M-esent ) ; they well merit investisration. Heing generally viseous they emulsify iiiipert'i'cdy. especially in tiie cold, and while some solvent like pine- oil oi' cresylic acid can be i iiployed. such solvents are expensive and tend to mask the etTect of the original reagent. It is pn ' able tiiat the employment of the moi'e liiiuid blast-furnace creosotes, with ]H-eliiiiiiiai'y heating, would be attended with good results. ('arbolic acid (phcru.l is a homologue of eresylie acid. It is difticult to distinguish between them, the smell and color being so iinndi alike. Ca'-liolic acid has a soluliility vai'ying from -i.M' ', at ir to 11. S:!'; at 77' in 100 parts of water. It is easily broken down by sulphuric aeid. yieldiiitr oxalic acid. It apjiears to be much lcs,s selective than cresylic acid in its action on metallic su'phiiles. and a sliirlit excess brings over a coneeiilrate hitth in insoluble matter. l''ri,i.-(>ii '^. My investigations eovi'r Mexican. Texan, and ("aii- foi'iiian crude oils. From .e known ditTerence in composition, it is not suriu-isint' that on any particular ore the results ai'e widely ditYer- ent. The metallurgist should have saiiii>les of all three on hand when OILS LSKI) IN' THE FLOTATION I'KiK i:ss 63 niiiiiiiif; tests. Fuel-oils are iint liit;lily selective like ercsylie aei... pine oils, etc., but are strongly emulsive; they secve the pui-pnse dI' giving lioily and iiiineral-carryiiig power to the relatively weak l)Ut more st^-leetive froths; they are ( iieap. (juiekly olitainalile, and. when used in moderation. Iii'iiig ovei- little gangue. It is well to inere;ise their tlnidity hy stcam-jaekeltiiig the eontainer from which they are fed to mi.xing-eoinpartnieiit.s. (ias Oil (stove-oili. — This is one of tiie distillati(>n jn'oduets of erude oil. It is a strong eniulsi''ving agent, which is. at times, most useful. It is worth a trial in running tests. It must bo used in very small (piantities. Crude Wood Turi)entine. — This is not tlie ordinary spiiils of tur- pentine. It is a dark reddish-brown li(|uid with a pungent smell. Oil gravit.v-flow machines I have found it of little use, as its action ill slight e.xoess is to bring over gangue freely. As an emulsifier, I niueh i)ret'er fuel-oil or tar-oil. On maeliiiies through which the tlow of pulp s maintaiin by meelianieal means, it has lieen found a valu- able reagent for the purpose of eontrolling the levels of pulji, through its phy.sical action on froths, hut this result is achieved at t!'e ex- pense of impure eonecntrate. unless the agent is used in the s*rietest moderation. I'iNK-OiLs, Wo()ij-T.\K Oils, Fik-Oils, \Vu.ii)-('Kr.osoTi>, Etc. — Tiie di'struetive distillation of soft woods yields a large numi)er of pro- duets, and possible reagents. I have found the oils derived from pine and fir to be more selective on ehaleopyrite than on ehalcoeite ores. Wood-tars and tar-oils are excellent emulsifiers. but it appears that the series in general gives better results on zinc and lead than on copper sulphides. I have found ])ine-oil useil in conjunction with crude sulphuric acid to give exeellent reemeries on weathered ehaleo- pyrite ores where cresylie acid had been a complete failure. There may be some significance in the fact that the action of suli)hurie acid on teri>eiics ' •■.;'-oils) and phellandrencs (crude euealyptus- oils) is to give in .tli eases di|)enteiies and terpinenes.- I men'ion this, as euealy]'ti..>-oils, which are prohibitive in cost in America, are. I understand, universally used in eoiijunelion with sulphurii' acid on zinc and lead ores in Australia. Ai'i'LiCAiULiTV OF TIIL I'uocL.-^s. — T. ■] . Hoover in the latest edition of his book on flotation'' repeats the statement nuide in the iirst edition, that there is a doubt if ehalcoeite can be recovered succes.s- II s'Tliorpcs Dictionary of Applied ('heniistry.' 1913. a'Coiicentrating Ores by Flotation,' 1912. G4 TIIK FLOTATION PROCESS I'ully liy tliitiUiiiii. This hiii'i'ly is ;iii ovvrsijjrht : im o:if is iiiui'c r.ij.r- iii/aiit than .Ml-. Ilnn'. ,r ,,f t|,,. ircciil work iIdir' ill Hotatimi. and I luivc uiily iiriT 1(1 iciVr 1(1 the very iii>rli recoveries tiiat lia\e heeii iiuale on a woikinjr scale on ciialeoeite ores, in Arizona, at several lari,'i' mills. • 'iilirite is considered a difticult mineral td reeo\(.r liy flotation. Ill tile case of one ore that lias come under my notice, in whicli the ciijinte occurred as a subsidiary mineral, the savinj^ amoiinied {,, a small pereentai:e only, cer'aiiily not as miicli as an ctHicieiii .^iiuie- tahle wiiidd iiave recovered. On the silicate and earhonate ores llieie is |ir(ihal)l\' no appreeiahle recovery. .Mi;iii wicAi. Sim: or tiik I'laicK.^s.— In my opinion, tiie devejop- iiK III of what ma,\ he termed piieiimat ic Holation processes \>\ ('iillow. Flynn. 'Cowne, and others, constitutes the most distinct advance (d' recent years. 'I'liey consist of a directly and clieaidy ajtidied supi)l.v of airdiulibles in a liiiely divided stati', to assist in brin mi.\iii^' and a ration omjiai'iiiie>:ts - by gravity at the cxpi'iise of a trifling loss of headroom. This less is more tiian comiiensated liy decreased power and labor costs, and siiiiplicily id' working. Finely divided airdmbbles can be diiveilv and ]ie?-t'eetiy api)lie(l tliroiigli many forms of porous media siidi as I'anvas, eoriinduiii stones, silica-tiles, sandstone slabs, etc. The mineral particles are seized upon and at once removed as concentrate, witliout having to be repeatedly sub.jeeted to a sort of 'fractional distillation' as in tli" older .systems. It is. in a way. the converse of I-;imore's vacuum ]irocess, and has the merit of beintr jiositive in action and under perfect control. Kemarkable results have been shown in the economy of reagents, power, and labor: also in the ea.se with which such macliines can lie started after any of these sudden stops in- cidental !(' milling operations. rioTM'iiiN \)V ((ii'ii;i; (i|{|; 65 FLOTATION OP COPPER ORES (From the Miiidiij and .Srifntiflr Press of May 29, 1910) Tlir Ivliliir: Sii- — Tlic iiiriitioii lit' my iiiiiiit' in your ivceiit article on this sul)ji'ft ti'iiijits me t(i otl'iT ii lV\\ remarks that may ho df general interest. Pneumatic flotation is already fully established in a number of phices and the results in comparison with the other and older schemes fully justify the opinion of your correspondent that it con- stitut(s tiie most distinct advance in flotation in recent years. The tirst pneumatic-flotation plant in tliis country was erected by iiie in February i:t1-l for the National v'opi>ei- Company at ^lulhui, Malio. a description of which lias already been published. The re- sults were fuily up to expectations from the very start. This plant consists (tf S rougher aiul 2 (deaner cells and treated 500 tons per 24 hours. A :iO-hp. motor furnished power for all the air necessary for both ini.xing and separating, and the oil consumption a\eraged as low as 0.1 :i Ih. of refined pine-oil per ton of ore. It wjus an ideal floating ore. Since then the Callow scheme has beeu adopted by nearly all tile oilier mills in the Coeur d'Aleue for the treatment of their Icad- ziiic line sand and slime-feed, and has been a means of simplifying their plants antl adding greatly to tln'ir recoveries. The other plants that I have since erected have followed the sjune general lines as were laid down at the Nat'onal. namely, air or tube-mill mi.xing and emulsifying of the feed followed by the separatoiy cells run in parallel. Kecent results at the Inspiration mine would indicate some • Ivantage (on that ore, at least) in running tlie ceils ill series of two instead of parallel, and without any sacrifice ill eapjiriiy tor a certain set number of cells. On an ore carrying a large |)ei-eeiitagc of mineral there is not iiiuch doubt that the series plan will give the best results iiiid possibly dispen.se with the necessity for (deaning the concentrate. The various elements that com|)ose the scheme in general are illiistiatnl ill tiie aiccunpanying diagram. The preparation of the pulp by any form of violent or propeller agitation is not neees.sary f(M' good resul's with the penuniatie proce.ss. Where the oil can be introduced into the tube-mill no further refinement in mixing is ;};■;•;■:;:.;;;;•;. T;;::;. :;!' ;;;;;:■:;;■. c;;:;:i;;i, always be dr,;vc •{•.•d Hi su."h cases air-mixing with the I'achuca becomes necessary. A standard separalory cell has a capacity that will varv froii! a C6 Tin: I-LilTATloN riidCKss li.) til I.) tolls ipt' iVcil [in- '21 Imurs wlim run in piirallcl. (Icix'iidiiig of iMimx' \i|)i)ii the fliiir;ii-trristii-s nf the rvi\. Two cells in |iiiriil!t'l will li:i\c aliiiut the same capacity as two c-ills in scries. Init a sli;;iitly Inuer tailiiii: may lie exiiecteil with the series treatment. The idiMius lueiliiim in the hnttinii nf the cell is a loosely woven panvas-tuill four layiTs thick, secured to the upper surface of a jierforateil jihite with liifurcati'd rivets and washers. This is the I)reseiit staiiiiard construction and has liceii ado|)teil al'tcr a ^reat many disa]ii)iiiiitii;^' experiiiients with other materials. It is irood lor .1 three or four months" continuous caiiipaiirn. and hecomes inopcra.tiv;' only thi-ouL'h the iilliiii.' ii]) ot' the pores li.\- dust that has lieen intriidiiced hy wa.\- of the Idower. Four or live pounds of air I'l-essure is am|)le in all cases to ^'ive the ])roper aeration, the (pianiily of air varyini: from (i to M en. I't. per sijuare foot of lilaiiket- surl'ace. When the cell is iiroi)crly ad.justcd and doini; its hest work there should i)o no violent a^'itatioii with the c 11. hut, only such agitation as is incident to i)riiper aeration. Any violent airitation jiroducintr a sui'i;inir of the liquid contenls has pi-oved detriiiieiital to irood results. A slope of :! in, per foot on the liottom has liecn I'oiind sutlicieiit to treat all oniini'ry ores after crushing; throiiirh :iii or 4<'-iiiesh. Treatinjr coarser inatei-ial or ores that contain a larfre ])ei'ceiitaire of iieavy i;an 111, is ami)le for the Pachuca ini.ver and 2.') cii, *'t. of free a • per minute is sui'ticient volume for mi.\inS I'^s ml. !_'ii'iitri- -,iiii|)lirii y. ainl lc>.s skill ri-ijuwril tn npiTiiti'. The ilitVriciirr in wrar ,'iimI Iiai- is iilivioiis. I'l-ddf 111' till' iijiiiasiil ri'i-Dvci'ii'S is shown in Talilf I. wliii'li ir|irrsriils u :!()-iia.\' I'Dinprtitinii. Ft is iiDticfiihlo that this im-rcase ill I \ri'y lii's iirinripally in tlir liinT and sliiiii' pnrtiniis of tln' T\nrK I ^^^l^-l-. ok i.miinc — riinuvinv I'Kkiod Total copper Copper oxidi' Flotation tailiim. Table tailiiit;. inroniblneii Mesh, Wei-ht. A. P. P.P. A. P. P.P. tailin:,s. '.'< ■■ ''c '', <7o — •;:. 7.0 n.3.s o..";; 0.30 1x29 0.1 ;; — 100 15.0 0.43 0.44 0.29 0.24 o.i:i — 150 12.0 0.44 0.3O 0.30 o.2.'i o.u; -r 200 !i.s 0.54 0.44 0.34 o -w. 0.22 — 200 5i;.2 0.5.S 0.42 0.56 0,4;; " 0.33 A ,era^e, all sizes. lO'i.o ... ., 0.44 0.35 T villi; 11 A\M.V-.I^ (IK COM F.MRVIKn l-"or tile saioe period C'li, Insol . FV. S, .V^'itatini; iiroopss ;;2.34 21!. 50 15.01 22.79 Pneuni.-itir i.iocess 31.24 2:!. 70 Hi. 79 23. S4 The festiltiii^' coiicontrates I'niiii the same eoinpctitioii are shown in Tahle II. wliieji inilieates that tho slightly h>\ver firade of coppei' is more than otVset hy tlio lower insohihle and higher iron contents. 'I'lie ])i-()(if of lower ])ower-ronsMni])tion is that the 10 cells of the Xatiiinal ('(ii)per ( o. witc run with a iiO-l ,•. motor and treated .lOO tons |ier d,i\' : the -.niie tonnaire Itcated hy a pi'o|)eller inaehine would ha\" taken close on to KIO hp. This figure has also lieen eontirmed at other plaees. The pow.'r nHjuired will vary from 2 to :j kw. -hours per ton. The froth produced from llie ])eiiuniatic j)rocess is much more ejiheiiiiral than that iirodiiceil hy iH-opeller-agitation nuiehiin's. a self-evident advantage when it eniues to collecting and handling the restdtiiig eoiieent rates. Regarding oils the remarks of your eoi'trihutor witli regard to eresylie m-'ul and the methods of analysis given are e.\treniely interesting ami v.iln.ilile. So far as my own expei-ience goes. I have Fl.iiT \TI(iN ny ciin'KK (ilil ~ 6» li not found crtM lie acid indispensable; at the present time and priee it is out of the question as a flotation apciit ; it Wduid s«-eni. moreover, that the same results can he obtained by the use of less retined and expeiisive reagents. In the Coeur d'Alenc on the zinc lead ores, wood creosote seems to jrivc tlic best results. Tlic Inspiration us«'s a mi.vture of HO'; Kl Paso coal-tar and 20', cieosotf. At one time we used a 2i to 5', addition of pine-oil, but this has since been found unneccs.sary. A mixture of 20^t' pine oil, 20^; cresol. and (iO'; carl)olii' was trictl exi>erimentally at the Miami mine. l)Ut just as good results were obtaiui'd by substituting Salt Lake creosote for the cresol and carbolic. These are both ehalcocite ores with some pyrite : the ehalcocite is easier to float than the pyrite. The pulp is neutral. The recoveries will approximate Mo'V of the sulphide-copper contents. I have tried a great many of the wood-oils, both the steam-distilled retined products and also the destructively distilled cnidc tars and creosotes, \m\ have generally come back to the coal-tar mixtures. The pine-tar ]ii-oducts are excellent frothers but the coal-tar products seem to act as collectors, and a combination of the two is often neces- sary. Acid sludge has been u.s<'d with good success on Butte copper ores, but the disadvantages of this are that it recpiires heat and also additional (pmntities of acid to get the best results. This means working with an acid pulp and prevents the introduction of the oil into the crushing plant because of the destnietive effect of the acid on anything but a .silex-lined mill. Some ores work best in an alkaline pulp and others in a neutral one. My own opinion is that in most cases the same results can be obtained in alkaline or neutral pulp as can be obtained in an acid one and the advantage of an alkaline or neutral pulp is self-evident. In one plant we had an interesting experience of this kind. The \\afer-su])ply was limited and all the milling-water was returned back to the mill. The flotation results gradually deteriorated as the mill-water accumulated acid; ihe more acid it got, the poorer the results. Lime was then added in the tube-mill and the pulp maril 2:?. I'HKKl.KKNTIM. KF.oT VIIiiN 71 PREFERENTIAL FLOTATION By 0. ('. H ALSTON (Kioni the MtiniKj tiiul Snriittic I'l'ss of .liiiie -'i, I'Jl.")) •I.NTKoDrcTioN. ' I'ri'tVrciitial ' Hotatioii is a specialized applica- tion of the flofative i)rincip]e in the .se])aratiori of minerals from their ores. It fjaint-d its lirst wide use as a name fur certain methods of float- ing nunerals in ctmiicitioii witii tiie Ilorwood j)roces.s mentioned below. 'Selective' flotation has come to mean (Ity common consent) the flotation of valiialile nnnerals (generally the metal sidphides i in the presence of undesirahle fran^ue-minerals. ' IVefercntial' flotation is the flotation of one of the ordinary Sfdectivel.v flotative minerals in the presence of another similar mineral. Thus, a iiii.xture of palena and sphalerite can he floated 'selectively' from a gangue of granite, limestone, or otiier eomnion ganpne-matcrial, while galena may he floated 'preferentially' from a ini.xtnre of galena and sphalerite. On account of the great interest manifested in this subject of late, I have thought that the following review of proposed or operating processes might be of interest. This review is largely a compilation of ])atent literature, but it might he well to call attention to the fact that, at present, patent literature is one of the best sources of information on the subject of flotation for one who does not have the opportunity to visit at flrst-hand the localities where the practice c.f flotation is l)eing used or tested. C.vTTEUMor.K. In IftO-i Cattennole (U. S. Patent 70^,250) made one of the earliest proposals for the preferential flotation of minerals. The method, as he (U^scribed it, was not exactly a flotation method, but it involved most of the underlying principles of flotation, and lience is of interest in this connection. As stated by Cattcrmole: '"The invention relates to the classification of the nu'talliferous con- stituents of ores which have been separated from gangue by oil or similar matter," and "consists in fractionally removing the difTerent constituents from th(> agglomerated ma.s.s*'s liy freeing the constituents in turn from oil, and thus obtaining them in a separalile condition by the use of emulsifying agents of varying strengtli and activity, preferalily in conjunction with an alkali." ''In carryinsr out fhp •Contributed l)y the Dpiiartnient of MetaMiirgioal Rese.Trch, fniversity of rtah. I). A. l.yon, im'lalliir«iat in cliarse: O. V. RalKton, assistant metal- lurgist. I'ublished by permission of the Director of the V. S. Bureau of Mines. 72 rilK Kl.dTATluN I'HIK !■>> |iiiiccss. Ilir iiiilallil'nnus liijillir Mtrtrloiiicriili-il Ky nil is nii\i'il mikI af;itiili'(l Willi ;i siiiuiioii of an t'liiuisifviti^ ii^'riit. siirli as a suliilili' siM|i alkaliin' nliali'. I'nr txaiii|ilr. In wliidi a !•■ itaiii proixntioii nf soliililf alkali. pretVraMy caustic pntasli or Mxia. lias been acMivl." ■'It is I'diiiiil tlial llif iMiiii'i'als vary in liirir atliiiily for nil i'iiipinyi>il in the altnvc inanncr. and thus tiy Ircatinn the oily niassis nr (;raiiul<'s in tli< liist |ilarlit of the re. and these granules woubi sink of their own ueij.'ht in an upward moving' current of water, such as that of a classifier, while the untloceulatcd tranj;ue woidd rise. He made the wording of bis patent, however, luoail ennuirh to cover the treatment nf i)rodiicts as obtained by true flotation. As an example of the workinjr of his jiroeess he uses an ore (•onsisting nf a silic-ioiis fxanu'ue. zinc-blende. co|)|ier pyrite. and u'aleini. which has been treated with an oil for the granulation of the mineial stdphide particles, and tlie latter separated. The oil i.s pret'erably one that is not readily eiiiulsilied. such as a liydro-earlmii nil, which will jiivc a wide raiifTe of stren<;tli in the solutions used later- in the breakinsr down of the ^rranules. The compntmd graiiuli-s .ire run into the tii-st ajritation a!)|)aratus where they are aj;it,ited with a sohition containii'-sr, say. CTo';,' alkali, by which the zinc-blende is "dropped nut," '\'\\f lemaiiiiufr trranules ai'i' jiassed into the uext similar ajjpai'atus, in which a solution eoiitainin<; l.'J'^,' soaji and I..""'; alkali is used. Here the eop])er pyrite is freed and ■inl.\' the pramdes of paleiia remain. As Cattcrmole proposed the use of so much oil. it had to ]i(> recovered b.v the use of stronfi alkali solutions. The rules foi' ])roportioiiiiifr the solutions took into aeenunt the iiiieness nf tiie nrc, ilie reiainc ]iroi>ori ions of iiic minerals, liieir jtliysical condition and chemical composition, also the kind of oil and I'liiulsifvinir at'eiits used, and the alkali selected. The liiicr the 1 riiLKKKKN n \i. I'f.iirv rroN 73 (III' thr limn' ciiiupact and colicsivo the iframili's fniiin'ii, ami lifin'c till' si milliner the wdutioii reciuiri'd to Ijreak tlu'iii down. With t^raiiuli's liiitri !>• of fralena. which breaks down with difltit'iilty, stronger solutions arc ncct'ssary than I'or those luMsistinir iiiaiidy nl" .sphalerite. With aniiiiiil 111' veffi'ti.l oils that emulsify easily the hri'aking down of the jTraiiuies will he too rapid for coiivenienrc. Tjie iieavy ri'sidiiuni nils and the heavy hydro earlion oils are the best. Oils may Ic lili-ndcd advanta^feously for this purpose. An alkaliin' solution of till' oil used in granulating is hest for emulsifying. Wiii'tlier or not Cattermole's proeess was ever applird is not kniiwn \i\ nil', luit it is not impossilile that its i)rini'ii)li's may he applied to modern tiotation froths. Wi .\ iwuurii. Following the l'. S. patents in their ehronological (inler. the next is .No. ICiS.Tiri. of VM'J. taken out l)y II. A. Wentwortii and assigned to the IIuflF KleetroKtatie Separator Co. It "relates to the separation of the ingredients which constitute ore nii.xtures, and partiiularly to the separation of sulphide ores from each other." '■'I'lie process consists in the preliminary treatment of ore mixtures eoiiiaining .several sulpiiides, which converts some of the sul{)hides, siiperliiially at least, into metallic compounds which are ditrerentiated in their behavior " with respect to flotation processes as commonly practised. To use the words of a later patentee, Mie surfaces of such minerals as galena, pyrite, and chalcopyrite are "deadened' by a Very short and slight roast in a roasting-furnace, while the sphalerite is unat^'ected. Thus the sphalerite can be removed by flotation from such an me. leaving the other suli)hide minerals to be removed by other meaiis. A few minutes heating at a dull-red heat has been loiiiid to lie sutlicient. This is a tyjie of proeess that has been tried in Australia under tile name of the Ilorwood. It is further described under that heading in this paper. li v.\i U.K. The same idea underlies the next patent, which is No. Ii4!l.(>(l2. of litlO. taken out by A. S. Ramage and asvsigned ti) the Chemical Development Co., a Colorado corporation. "This proeess has for its ob,ject the separation of the valuable minerals from such ores as chalcopyrite, bornite, or crul)escitc, and mixtures of the same with pyrite, in which ores the copper is in chemical combination with the iron; and also from such ores containing zinc-blende. The lueliiml iS riiSO appiiertiiie to OOUlpOUiUi ores, SUeil nS tiiOst; pyrili'. '.villi a nuitriit uf aliout •'*', inpix'- and .in to 4(1'; snliiluir, Tlu' ore is roast. d at alxtiit a nil liiat lont; fnoiidh to dccoiiiposc tiif pyritc siitrlitly and not alff't the rlialcopyritf. •■The liiiriit ore is then eruslied to at least I.') mesh and |)asseil tliroiijrli II solution of aeid snli>liate of soda and nitrie arid (the solution lieins; formed by addin>r nitrie aeid to sidphate of soda), whieli solution is kept near the lioilin^' jxiiiit. The eopi)er suljiliiile iiiiiiiediately rises to the loi> of the hath and eaii he skimmed otT." The eojjpiT dissolved in the hath can lie reeovere.i in known ways. This im-thod of notation I hot aeid hath- is not new. Iiavin<; been patented by I)e Itavay. I'otter. I)idi)rat, and others The fraetional roastinfr had been previously patented by Wentworth. and so the only thing that seems new is the eoiiibinatioii of methods. A seeond example is that of an o.-e eoiitainin<,' i)yrite. ehaleoj.yrite, and /ine-lilende in (piaiitity. The (U-e is roasted at a temjieratiire of not over 60()°('.. so that otdy the iron pyrito is deadened. The roiisted ore is then subjected to the acid su!i)liihurie acid for the dissolution of the zinc, to bo recovered from solution by any familiar process, such as .■lectrolysis, the copper sulphides being sent to the copper smelter. There are certainly most interesting facts disclosed in this ()atent. The great resistance of copper i-:ulphides to the roasting process, as eompared with the suli>hides of zinc, is something new and will be a most valuable characteristic, if true. The third example is that of the ores of the Cobalt district, Canada, where eobaltite. niccolite. ehalenpyrite. pyrite, and native silver occur. All the sidphide and sulph-.-.rsenide minerals are floated, leaving the silver in the gangue. The sulphides are roiusted at about 800° C. and everything is decomposed except the copper sulphide, which <'an be tloated trom the calcine. Again «e imve meniiou of the almost incredible property of copper sulphides to resist roasting. The next patent was that of II. A. Wentworth. amplifying on I'KKFKKKNTIAI. KI.ropertie.s enhanced. As an example, a mixture of zinc and iron .sulphides, when treated with chlorine ^'as in a .slit;htly damp slate, is so altered that the hlende will Hoat on a lilmflotation machine much helter ♦' ii before treatment, while the pyrite has a coating formed over its surface, whii'ii is much more easily wetted, so that if will sink. Still a further example is the a[>plieation to tlic s<'paration of pyrite and ehalcopyrite. The latter is attai'ked nuich .slower than pyrite; hence it can he floated when lioth are present. A similar behavior of the minerals is ob.served when lliev are su.spended in wafer eontainin>r di.s.solved chlorine in the proper concentration, but the best work seems to be done with minerals fed onto one of the film -flotation machines, such as that of n. Iv Wood (d' Denver, althouKh Weiitworth pives the (lesii;n id' one of his own in the specification. It is easy fo .see that with chlorine- water and one of the mechanical frofhintf methods (d" Hotation the soluble coatiiifp. that are formed on the surfaces of the iiunerals would be simply washed off and the preferential part of the flotation lost. Tests in our laboratory seem to show this. So far as is known to me. this process is not beinjf useil. HoRwooD. This process of preferential flotation is practically the same as that described under Wentworth and RamaKo. It has been worked for some years in Au.stralia and received careful tistiiiK by the Zinc Corporation. It depends upon the 'deadenins;' o{ palena ami j)yrite in a slioit roa.sting at .'!()() to .')00" ('.. whereby the fralena is coated with lead sulphate and the pyrite with iron oxide, while the sphalerite is unaltered. This allows a sepaiation of the undesirable zinc fnmi the lead-iron-silver jiroduct and allows their s«>parate marketing. This process has received more cai-eful attention than any other process, and reference to original articles is best.f Accord- ing to the data given in some of this literature, it appears that it is pos.sil)le to take a flotation concentrate containing 36% Zn, 15% Pb. and 22 oz. Ag per ton, and divide it into a zinc product running as high as 50% Zn, 7% Ph, and 1.5 oz. Ag, and a lead I tT. .1. Hoover, Concentratine Ores by Flotation"; ^fi>l. ,1 Fiin Wnrhl, jnK- IS. 1914, p. 96; Enfj. ,( Min. Jour. (1914), 97. p. 120S; Minitifj and Scientific Press. April 18, 1914. p. 657; Metal, d Chem. Eng. (1914), No. 12. p. 350 and 592. THE FLOTATION I'ROCESS l.nMu.l .ontiium.- :i>' IM.. >', Zii. au.l 42 o/.. Ag per ton. Tins is of K'lvi.t iiitrnst In all pro.lucers of -wiuplex sulphiJo' oivs. as the miUiiijr <'f coarsely crystalliiu- material has presented iiiueli dirtieiiltv in the past lor the reason tliat some linely divided material 1 slime is hound to form in crnshmg. and while the eomliiued lead and /in.- sidi)iiides ean he Hoated nowadays without much ditlieiilty, Ihr nnxture is of far less valne than the '.v.o minerals separated. 'I'liis -s important enough, not to speak of the possibility of treating III.- naeroerystalline sulphide ores and those containing gangiie of high si.eeilie gravity, sueh as harite. While dotation lias been a boon to the eoneentration of all sulphide slimes, preferential tiotation is nm.h more imp.vrtant for the ores eontaining undesirahle coni- hinations of suli)hid.'S. Hen.'.' Horwo.id's work should receive th.' hiirhfsl praise. Another detail, as regards this pro.'ess, is that ',):> lb. of sulphuric a.i.l i>.i 1..1; of .-ri' is neces.sary an. I 2 t.) .i lb. of oleic acid for the ri..t:iii.m «\- th.' unalteiv.l /.in.'. All of this appeared in Horwood's rirst patent. No. 1 .l)20,;{.');{. of V.)V2. and he later .ame mit with iMipi-..'v.-m.mts on the process in patent No. 1.108.440, of 1914. In this l.il.r patent ii" state.l that he had found there was a tendency r,,i- th.' silver to f.illow the /..ne. which is undesirable. Imt that this ,,,ul.l li.' prevented by simply wa.shing away all soluble salts on il,.. roiu'cnliate bef.ire il was subjeete.l to the deadening roast. This reduces the amount of oxi.li/ed zinc formed, and lo.st by so!-. with tli.' ])ulp at a temp.Tature of about 120 F. It will be seen that th.- Horwood process has been applied only 1.1 .-.Micentrat.'s from previous tiotation or from otlier concentration pro.-esses. This is the logical i)la.'.' t.) aj.ply it, as there is no ol)ject in h'aving a n.m-H.itativ.- galena .ir other suli)hide mixed with gaiigue. by using I he pn>.'ess ..n crude mv ', ■ ■• same remark applies to m:iny of th.' .>tlier pr.i.-esses. To be sure, there has l)een some suec.-ss in ih.' Australian mills as well as in the United States in the treatment of mixed galena-sphalerite oncentrates from flotation maehin.'s ..n .■.in.'..iil rating tabl.-s. As an .'xamjile. the Tiii.her Uutte mill is milling Ih.' tlotati.m .■.Mic.'iitrat.' .)f a /ine ore ontaining some /.ill.' coii.'entrale .-arrying ^V ; Zn. l.o^; Vh. and ^'"< insoluble, llow.'ver. this method has not always ni.^t with th.' best r.'sults. aii.l wh.'i-e the proportiiuis .if l.ti.l ao.l /in." in or.liiiary .■.imi)lex M^ 7' I'REFERK.VTIAI, FLOTATION' siilpliidu (•oiiceiitrati'S are al>i)ut ciiiial it is (iiiito lianl to gvi two products that are sutlieieiiliy pun'. VVIiere it can lie done, it is certaiiily more desiraliie tiiaii the more complex traetioiial roasting and preferential Hotation i)roees8e8 of llorwood. Wentwortli, and Kainaj^e. Lystkk. Tills is another process that lias reeei\ed consideration liy tiie Zinc Corporation for the year or two preceding the European war. Lyster's process is carried on in neutral or alkaline solutions (never acid) of the sulphates, chlorides, or nitrates of calcium, magnesium, sodium, potassium, or of their mixtures, or solutions of manganese, zinc, iron, acid sodium, or sodium-potas-sium sulphates. I'sing eucalyptus oil or a similar frothing agent, the agitation of the pulp takes place in centrifugal pumps, throttled to give further agitation, and discharging i :o spit/.kasten with constricted tops. It is ss and metals. By taking the various froths obtained from subjecting the pulp to varying conditions, and cliussifying on apparatus such as concentrating tables it is often possible to get good separation of the minerals contained. One example cited is that of an ore containing sulphides of ie'id. copper, and /.inc. From this t of oil u.sed. it seems to be possible to float galena in the presence of sphalerite, though the lead product obtained always carries a good deal of zinc, and it is impossible to get all of the lead out before the sphalerite is flja+ed by the addition of further oil. This is practically an application of Lyster's process, except that pure water is used instead of the solutions recommended by him. However, there can be no doubt that 'he addition of certain substances to the mill-water does help in this type of flotation. In another phm' where an ore containing pyrite and chalcopyrite is being treated, the first froth contains most of the chalcopyrite in a finely divided form, while only a small amount of the pyrite, m large pieces, comes to tlie surface. The property of chalcopyrite to disintegrate into very fine flakes on crushing has bothered mill- mer. in the old days when the- pro luctiou of slime was kept down to a minimum. Now it seems to be an advantage. These two instances of "controlling flotation" conditions are somewhat different from the ones implied in the Nutter and Lavers patent, and it is doubtful if it could be helrt to cover these cases, at least more than iii part. However, too much attention cannot be given to their )ateiit, as it discloses the methods by whicti preferential flotation • ill be first developed successfully, as far as I n-ii able to see. Grkh.nwat and Lowry. a further develop.nent of the idea of using a solution of some ci-imical that will permit true preferential flotation of one mineral in the presenct' of another flotative mineral 80 THE FLOTATION l'l!()(K>: is (-(.titaiiird ill tlic pat.iit of II. H. (Iivniway aii.l A. II 1'. Luwiy, No. 1,1U'J,7:{.S of 11(14. Tliey disoov.-inl tliat "if a salt of fhroinimu (such as sodimii liicliroiiiatf or i)()tas.siiiiii hiclinuiiate) is iiitrotluoed ill solution into tlio fin-uit li<|uors, or if tlu' niatfi-ial to In- tivatt-d is subjected to tile action of sueli cluoiuiiiMi shides on the other." Three examples are cited: (1) A luolybdenum ore coiitainini.' 1.')% molybdenite and 2o',[. iron pyrite was crusheil to pas-s lOO-niesh screen and treated in a froth-tlotation apparatus with four times its weight of water <-ontainiiii,' 0.2')' l sodium bichromate, and heated to 120 F. One pcmnd of eucalyi)tus oil per ton of slime was used and tiie Hotation product consisted of !>:{',t MoS_, and 4.!)'; iron pyrite. Attention should be called to the fact that this example docs not tell as imich as it would seem to say. for the reason tliat molybdenite is one of the nu/st easily fionted min.'rals. I believe that work of a charai-ter more nearly comparable with this result could be obtained witiiout the use of ehroniates. The si'cond cxami)le cited is of a co]>per ore containing; <>.■>'. copper and :jr)';i iron. This, likewise, was crushed to pass a 100-mesh screen and digested in a hot sohuion of 1% sodium cliromate for about :{() minutes, the liquor decanted and the mineral treated in a notation machine with one pound of eucalyptus oil per ton of dry slime. The flotation product contained 19% copper an.i W:!' } irmi, while the residue contained O.TVo copper and -K.'Z^/c iron. When we 'rememl)er the ca.se cited above of s<>parating the chalcopyrite from the pyrite liy virtue of the fact that fine grinding takes the copper down to a much finer i)roduct than it does the iron, we are 1.<1 to wonder if this i>roeess is really necessary for this kiiul of ore It may be that a better gra.b- of product and a higher extration can be obtained by this method than witl'out the a.ldition of bichnunate. but otherwise it is doubtless possible in most cas(^s to do the same work willi proper control of onlinary coiulitions. Tl'.eir third exami)le is of a lead-zinc slime containing IS.*')',' lead and IS'i.I^-:, zinc, which was digested for 30 minutes in a warm soluthui of 1^; sd 47.2% zinc and G';; lead, while the residue contained :n.6% lea.l and Ifi.lJ^, IKKKKKKNTIAI, KI.U'IATK l.\ 81 /inc. Tln' solution was licahd to 120' ('. These are iuterestiug lij-'iiies. lint tliere is too tinirli /.ine in tlie leacl eoiicentrate. Here again I feel that the work is not nineli better tlum it would be without the aid of biehroniates. Hy taking advantage of the fact that galena floats more easily than blende, it is possible to get a galena froth from an ore that will contain 54',; lead and 15% zinc, while the blende-frotii that follows will contain 37% zinc and 20% lead. This type of work eri-s in the other direction, that is, in liavi!ig too nnn-h lead in the zinc product, but the point is that the addition of bieluomates does not make a .separation which is any more advantageous than does preferential flotation by other methods. However, the fact that the galena can be deadened by treannent with a weak solution of sodium bichromate is most interesting in that it shows that a true preferential flotatio'i is possible. It is a.ssumcd that the action of the bichromate solution iuu.st be that of oxidation of the surfaces of the galcn-. to in.soluble sulphate, while such an action on the sphalerite emdd not be possible, as the zinc sulphate would dissolve. The ♦reatment of the high lead-zinc product of this last mentioned preferential flotation product by the bichromate process might be a useful method of cleaning this kind of concentrate. It is probalile that successful preferential flotation will develop along such lines, though bichromates are not the only chemicals that will be used. AVliih. the results obtained by this process have been shown to be cj.pable of duplication other- wise than by the ui-e of bichromates, this fact of the jjeculiar m. tion of weak l)ichromate solutions is thankfully accepted and further worl: is urged to discover if it I'an have a field of application p"culiarly its own. Br-\dford. Another process along these lines is that revealed in British Patent No. 21,104 of 19l;<, by L. Bradford .>f Broken Hill. He chiims the use of solution that will wet one of the sulphides wiiich it is desired to separate from the other preferentially without I'heinically altering the same. A medium which will wet galena particles and allow splialerite and pyrite to float unafTected is a solution of one or more of the alkaline chlorides, slightly acidulated and heated to about 120 to 160° F. On account of its low cost a solution of sodium chloride is used, and Bradford .states that there are no definite requirements as to how concentrated the solution shall be. but suggests a 10',' NaCl solution as about the right strength to tise. The acidity should be about 0.1 to 0.2%, for a higher am(,unt THE 1I.OTATION I'KOCKS.S than l^r will cinisc tin' floliilioii nf siiilcna on npoount of tin' fornialion of liydroirrii siii|)liiili' hiitililcs on its surl'afc. He states that, it' till' i)niitss i>s aippliftl dii'iM-tly tn crudt^ ores the use of a i'rothiDjr a^tnt is not niTcssary. aitlioii^'li it will cause no harm it' added. Any well-known M|»paratiis ean be used for the Hotalion. The invention may he appliid either to the erude ore or to the mixed flotation coneentrate from the ordinary method of flotation. ^VIlere the plant is useil on erude ore the tailin-^s from the flotation of the sphalerite and the ]>yrite are agitated again lu pure water with a frotliin-; aireiit in order to float the galena. On aeeount of this requirement it is thought better to make a mixed coneentrate first by ordinary flc»tation and then separate preferentially as above described. Tliis latter method, however, makes a higher-grade /ine concentrate. When treating ordinary mixed flotation concentrate, it is best to remove the oil on the surface by the use of au alkaline or an alkaline carbonate solution, or by either. Further, finelv ground material is liable to agglomerate too quiekly, so that some of the galena will be entrained mechanically with the agglomerated sphalerite and decrease its value. In tiicse cases it is desirable to add iin agent that will retard tlotation. Substances suital)le for this purpose arc >ulpiiitcs or tliiosulphitcs of alkidies or sulphur dioxide, but they must be used sparingly and with care, or they will entirely spoil all flotation. He thought so nuidi of this latter step that he later incorporated it in a scj)arate jjatent (Brit. I'at. No. 1!1.844 of 1014.) No further (les<;ription of this patent is necessary. There arc many other proposed methods in the ])atent literature of Hnglaiul. (!e. many. France, and the Fnited States, concerning wliich I am not fully informed, but it is believed that most of the important iiies have been reviewed. Many interesting details are disclosed, sucii as the fact that galena and sphalerite will not float in a solution containing zinc chloride of the right concentration and aciditicd by hydrochloric acid ((ierman jtatent, Np„ 282,2;U). Aniline eomi)ounds aic sai.l to allow flotation of galena in preference to sphalerite, etc. It will doubtless be noticed that little mention is made of the kinds of machinery used in the above methods of i)referential flotation and there will do\ibtless be some question as to whether or not these principles can 1h^ applied equally well in the mechanically-agitated and in the i)neumatic-agitation machines. Most of the above processes. .I-.-p-'-- ri.or vrid.N at tiik inspikation mink, akizona 88 wiiiic liiit spcciliiiilly stat<'il, have Itceu worked out witli tli(> aid of iiiii-haiiicidly-afritatcd iiiacliiiics, lint it is possihle to ai)ply most of iliiiii to tlie pciiuniatieally-asitiited rnacliincs. stirli as the Callow or till' Touiie. Siieli maehines, owing to tlie economy of power in inakiiii; fmth, and the easy control of flotation eon(]itions, will ciiiulitlcss iiiateiiMlly .issist in the (li'\rlopinent of preferential rtotatimi. FLOTATION AT THE INSPIRATION MINE, ARIZONA By William Motherwell (From the Milling and Scientific Press of July 3, 1915) Tiie Inspiration Cousoliilated Copper Co. 's mine near Miami, in Arizona, is estimated to contain i)7,l-l;3,U()0 tons of 1.63% copper or^, mostly in the form of ehaleocite. The ore at present being mined contains about 0.20% metal in the form of Ciabonate and silicate. For .S( me time past the company has been experimenting witli a view to finding the best method of concentrating the sulphide ore before sivielting. The fii-st test-mill consisted of two sets of rolls, oi Chilean mill, one llardinge conical mill Z ft. diam. by 12 in. cylinder, Richards hindered-settling classifier, Deister tables, some kind of vanner, and a 50-ton Minerals Separation flotation machine of standard tyi)e (Hoover's single-level apparatus). This mill was situated close to the Joe Bush shaft, on top of the orebody, ana is now dismantled. It is understood that good results were obtained. On a change of uianagement taking place, a new test-mill was erected near the old leaching plant of the Black Warrior Copper Co., about H miles from the new twin-shafts through which all ore will be hoisted wlien the lai'gc mill is running. This mill will be the largest, or rather will handle the largest tonnage, of anj' mill in the world, namely. ir),000 tons per day. It adjoins the test-mill as can be seen in the photograph published in the Mining and Scien- tific Pnss of May 20. The crushing and concentrating capacity of the test-mill is about 1000 tons i)cr day. but it is limited by the capacity of the classifiers, elevators, etc. The ore is at present hoisted tl "ough the Scorpion shaft a!id broken in a 'K' Gates crusher close to the shaft. From there it is conveyed to the 30.000-ton flat-bottomed steel and concri'te b.ins 84 IIIK I'l.OlATIiiN l'K(P( K- nttiifhcd to the cnislur-statiDii iit llic new slial'ts. It is tln-ii tiaiis- Idirti'd tci llic tistniill in liipildshy (liiiiip lars cacli liavinn a cjipacity of (JO tons driiun liy steam loi'oinotivcs on a staiidardt^autJc railway. A ])art ot' the iifw inill-hins i wliidi arr of slci-l and tiMU^li- sliapi'd) is set aside for tlie use of the test mill. On leaviufj; these bins the ore falls upon a t ray-eon vyor. thi'n to an inclined ruhher- lielt conveyor, where it is auloniatically weifjhed. At the heail of this conveyor there is a iiiaKin'tic pwlley that removes pieces of iron and steel which may have f,'ot nii.xed with the ore. At this jMiint tiiere is a trriz/.ly and a ;i()-in. Syiiions vertical-disc cnisher. From licrc an imdinc-eonveyor carries the ore to the top of the test-mill, where it is divided into two streams, one f?oing to a shakiii^i s<>rcen from which the oversi/e falls into a 4S-in. Symons iiori/.<'ntal- disc crusher, where it is crushed dry, and the other to a .') ft. (j in. liy S ft. diani. Marcy liall-mill, where it is crushed wet without previous st'reeiii- '. The product of tli Symons machini' is fed to pebhlc-niills without any ela.s.s:ticatioii, heinf: distril)ute(l in varying proportions by a mechanical device. This consists of a lixed hori- zontal circular vess(M lO.'i inches in circumference divided into four sections liy vertical sheet-iron partitions that can be ad.justcil to einart 23 in. long driven through spur and pinion by two idt transmission from motor. :! One llardinge conical mill, 8 ft, diam., with cylinder 72 in. long, with herring-bou" gear engaging with pinion on shaft direct driven by motor. 4. One llardinge conic;.l mill. 8 ft, diam,. with cylinder :!ti in. long, driven in the same manner as No. '-V rr,iiT\iiii.N \T Tin: in>i'IU\i ion mink, vki/.onx 85 "i Oiii' Hiinlin^c ((iiiical mill. M It. (iiiiiii.. with cyliiulcr 44 in. loiip, driven ill siiiin' way jus Xd. it and 4. Hotli .sik'x and Kl Oro iiiiiii(is wore tried in the I'vlindrieal part, and [leliMcs vet in eenient in the ecuiieal p;irt ; and, in nne mill, .steel i)lates. wliieli, iiiA>.ver, did not la.st lonjj. Each pchljle-mill h.is a dra>r- of the tiilie-mill the oversize is retmiii'd to the mill hy the dratj-chussitier, which is paralled with the mill. Hoth Danish and California pehhles have hccn tried. The product of the Jfarcy hall-mill is classified in a duplex Dorr classifier, and the oversize returned to thi- same machine. This. a.s a tine crusher, has a capacity of ahout l:} tons per hour. Of the final product only ahout I'}', remains on a 4H-mcsh screen. The mill is simply a strongly hiiilt cylinder supported on trunnions, contains ahout 10 tons of chrome-steel or manganoid halls, and is revolved at 22 r.]).m. It was formerly feiciently high to flow to all the flotation plants without undergoing any preliminary tahle or 86 TUK FIOTATIDN I'KdCKSS vaiiiit'i' idiicfritralKiii. 'I'lii' tVi'il is distrilditcil in Ilic Hotiition plaiitN in tlu' l'i)lli)uiiii: way : It Hows into the (•cntrr of a liori/ontal, circular, rcvolviiijr ai>[>araliis ot' slicci iron divided iiitn five concentric circles or ring's. Hadi circle lias 20 holes in the liottoni. and the pn)p()rtio!i of I" 1 to each flotation |>lant is rcpridated hy openin>{ the proper iiuniher of holes and allowing the pulp to enter a launder alontf which it flows to the flotation plant. Thus if the ririR that receives the fet'd intended for one parficulnr plant has 15 holes plupped and ."> open, this plant is, of coins*', receiving 2ij^,' of the total feed, and the actual tonnage passed lirouRh it can be calculated. .\iitoiiiatic samplers, worked tiy a water halnnce. are userh enclosed bevel-gearing by a pulley on a hoii/ontal shaft. The overflow from tiie first si.x compartments \V!us sent to the concentrate-bins without 'cleaning' or further treat- ment designed to raise the grade by I'liminating insoluble matter anil the ovi'i'tlow from the last two i'omi)artments was returned to the li(>ad of the machine. This machine was discarded. 2 .\ 12-compartmcnt Minerals Separation machine of standard type, of the same cai)acity and driven in the same manner as \o. 1, the an and compressed air were u.s<>d. The agitation compartments contained cast-iron Iiartle-|)late8 li.xed to the sides, and the im()ellers were ditTerent from those nsed in the standard machine, hut the spindles were driven in tlie nsnal way. Tiie dis<'liar>rc from the agitation compartments to the flotation con.partments was IiIkIi up. Tiie air used for the Jieration of the pulp was introduced throupii a hole in the Itottoni of each n>{itafion compartmi-nt at a pressure of al)out 2 Ih. per square ineli It ditl not pa.ss tiirouKh any porous medium. Tiiis machine had the usual valves and suction-pipes in the bottom, hut was after- ward alten'd to (.')) a machine of I he Hehhard type, with agitation gear of the standard Minerals Separation pattern, hut with horizontal discs in place of the usual screw impellers. Kach spindle nuikes about ;5tM) r.p.in. In tiie Ilebbard iiuichine as us«'d in Australia the agitators are driven from below. There are no spit/kfisteu, the overflow of ('onccntrate-froth taking place from the agitation com- partments. ('oiise(piently there are no suction-pipes and valves in the bottom, and no plugs to drav and re))lace when a stoppjige takes place. The wooden |)artitions between the agitation compartments have been removed and cast-intu baffle-plates about 15 in. high substituted. Air is blown through eight holes in the Imttom as in Xo. 4 nuiehine (des<'ribed above) and water under pressure is used to j)revent pulp from entering the air-i)ipe. On a feed of about .'KM) tons per day this machine has given good results, and is still in use. The low-grade 'Miiiccntrate made by this machine is ■(■leanerinidum. Hubbies are formed, that adhere to the oiled sulphide particles, forming a froth overflowing at the top nf the cylinder into a launder, whence it flows to ('.]) a similar cylinder at a lower level, where it is 'cleaned.' The tailing from the first cylinder escapes through a hole in the middle of the earborundnni i r-- 1^1 , MICROCOPY RESOLUTION TEST CHART ANSI and ISO TEST CHART No 2 1.0 "^K m I.I I 2.2 1 2.0 1.8 '•25 III 1.4 i 1.6 j= APPLIED IN/MGE Inc -a;p-. 'ttH 'O" i*»t] I *8,! - OJOO - Pnone 288 - 59«9 - ro» 88 THE n.OTATIOX TROrKSS atiil Hows tliniiiirli ;i j;iiom'-iicc1< Ikisc ( Iiv which the wat.T-h vd in the tii-Nt ryliiiilcr is rcEfnialcd t(i i4i aiiothiT cyliniliT wIhtu it rcci'ivi's similar trcatinciit ami tiioi'c coiicciitratr ovcrtlows. This coiicontrate also is re-lrcatcd in the saiiif cyliiidcr as Iho coucoiitratt' i'l'diii tlu> fii'st cyliiidt'r. and tln' tailinji from this cylinder or ■cleaner' is returned to the I'achuea a^'itator at the t()]> of th(^ huildiin^ liy a eeiiti-ifnf.'al ]>iiinp. The ail' is fui-nished hy a l{oots tilouer. 'J'his plant was dismantled. 7. A Callow ])lant eonsistiuf; of 1 1 i Paduica ajritator l.S ft. deep hy 4 in. diam., i "J i five cells, each S.t ft. lon pi])es is eompo.sed of carborun- dum, and air from a blow(>r is forced throufih them with the same effect as in the Callow, Towne-Flinn, and other pneumatic processes. Perforated wrousriit-iron ])ipes wrapped with flannel or canvas have also been used. The tailiufr from the tii'st tank is re-treated, ami the eonceiitrate from all tanks is re-treated in a 'cleaner.' This plant is still runninfr. A siTuilar machine is in use at ilorenci. and one is beinp: built at Cananea, Sonora. n. The company's metallni'jrist has devised an apparatus intended to combine the best points of the other maehines, but without infrin;?- inij on an.v patents. exce()t those of th(> ^linerals Separation Amei'ican Syndicate, from whc)m the eom|)any liolds a licens(>. Tt is called the lns]>iratiiin machine. ,\t tirst it resi'udiled a Callow api)atatus with an almost Hal bollom. Ilie air beiu'r blown through <'anvas, but the fi'oth overflowed at one side ol' the cell onl.v, and there were pai'ti- tions uhicii, however, did not reach the bottom. It was twice as Ion" !i« the 0!''ate \\':is re-treated if! a smallci' machine of tiie same type, and the tailing from this machine 1 I.DTATln.N AT Tllh: INsniiATlON mim:, AKIZONA 89 was, as usual, returned to tlie ' roufzlier" eell. Keeently otlier jyoruus media lor t'alse bottonis have been tried. 'J'he iimeliiiiu is still in the experimental stage. Jt will thus he seen that the e(imi)any has spared neither time nor money in endeavoring to find the best flotation process. The test-mill has been working' since January ]!l]4. and about 50 flowsheets have been tried. In the laboratory there are (i small flotation maehines ot' the .Minerals Separation type in almost constant use. The tailing from all the flotation plants is run over tables, those in use being Wilfley, Deistcr ]\raeliine Co.'=! double-deck simplex sand eoneentrator, Deister Machine Co.'s four-deek table, Dei.ster slime table, and Deister Concentrator Co.'s double-deek table. At one time the ore was concentrated on tables before g')ing through the flotation process, but this was not found suitable for the Minerals Separation jirocess, as it left too little mineral in the ore, and for this and other reasons it was discarded. The mineral s;ived on the tables is mostly pyrite. The 2:!4 tables in the new mill are Deister Machine Co.'s double-deck type, the same as u.sed in the Miami Copper Co.'s mill. No tests were made with any kind of vanner. The sand and slime were run over the same tables without classifleation, but this will be altered in the new null. The tailing from the tables flows to the dam. the retaining-wall lieing built by allowing tlie coarse sand to escape through cones or inverted pyramids attached to the tailing-launder. The concentrate from all flotation plants and the tables, contain- ing about 28% copper, IG^', iron, and 267o insoluble matt^M-, goes to a drag-classifier. From there the coarse concentrate goes direct to an Oliver filter and the fine to a V-shaped settling-tank, thence to the filter. The concentrate, after filtering, still contains a good deal of moisture. It is trammed to a bin adjoining a branch of the standard- gauge railway and loadeii into bottom-discharge steel cars belonging to the International Smelting Co. Formerly it was sent to El Paso. Te.xas. Water for the mill and domestic purposes is ol)tained by pumping from wells in the flat country about three miles distant. A large concrete reservoir has been built on a hill near the mill. Electric power is ol)tained from the power-house at the Roos'svelt dam about 40 miles distant, belonging to the U. S. Reclamation Ser\'ice, and the service is fairly .satisfactory. The Inspiration company has an in- i( Tc.si. in Tne pov»er-ihni.v at ilie Internaiionai smelter neai-by, where, in ca.se of emergency, a supply of electricity can be generated hy 90 THE FL(.)TAI'ION I'KOCESS stfiuii lioin \v;inI>- lu'iit rroiii tlic rcvrrlieratitrics aiul Iroiii oil-liiL-d Stii'liiiL' lioili'is. As iiii>Mtionf(l III ill.' aiinnai iTpnrl nf tli^' rompaiiy la siiiiiinary of . f , 1 Jymo'^i l/frTcj/ ..d/L^A - -.^££2i u/ev ^ * , « . ' i -~i '^- ; > 1 \ -f I I ^^V£ C/ass///i^' \M,.r.-'}/, fa/tef/T^a^ 1"^^ \Sm^rer\ FUl. Iti. nOWSlIKKT OK THE INJil'IK.M ION .Mill.. THE RO.\STI.N(, HJRN.\CK JOB CONCEMB.MK IS AT THE S.MELTEB NEAB-BY. wliicli appoarc-a in the Minituj and Scientific Press of May 1, 1915), I7"i.722 Ions of ore was treated in this mill in 1!»14, so. althougli only a test mill, it handles a fairly large tonnage. Dnring tVie month of K°hrn:irv I'Jir). OO.iro of the eopnor occurring in the form of sul- phides was recovered. The mill has been visited hy mining men from all parts of the world. l.iiTATIIlN 1\ A .MKXIIXN MILL 91 FLOTATION IN A MEXICAN MILL lly A Si'KciAL Correspondent (From tilt- Mii'iii',1 mill Siientifiv I'n'ss of July :i. i:n.3t l'Ki->t;NT t'oxcKNTinriNn M HI KIDS. Tlie mill ivceives 200 tons piT day of crude mine ore. After lieiiii,' erii.slied lo 2-ineh size, tliis ore is passed over a pieking-helt, where oiu' ton of liigli-grade ore and four tons of waste ai'e removed eaeli daj'. Tlie remaining l!t5 tons of seeond-eliuss ore is crushed in stamp-batleries, to pass a -t-mesh sereeiL Lime-water, in the ])roport'on of 7 of water to 1 of ore, is added in the battery. The pulp from these Is elassitied roughly, the coarse sand being ground in a llardinge mill to pass a 20-niesh screen. Tiie pulp is again elassitied roughly into four sizes of sand and one size of slime. The sand is concentrated on Wiltlry tables and the slime (after being settled to 7 : 1 in cone-bottom tanks] is eontentrated on Deister tables. The slime-tailing, from the Deister tables, is re-eoneentrated on vanners. The tailing from the vannei-s s«'ttles to 'AS tons of water per ton of slime; the water being further reduced to ij:! in a vacuum- tilter. The filter-cake is washed with weak barren solution before being sent to the cyanide plant. The saiuJ-tailing from the WilHey tables of the stamp-n>i!l is classified carefuU.v in mechanical classifiers; the slime under-size joins the slime-tailing from the re-concentrating vanners, and the sand (after the addition of cyanide solution) enters the tube-mill circuit, where it is .joined by 50 tons per day of dump-tailing. AH tube- milling is done in cyanide solution. After passing through the tube- mills, the combined current and dump sands are re-concentrated on Wilfley tables. The tailing from these tables is classified, the coarse saiul re-entering the tube-mill circuit ami the slimed sand being tbick- eiu'd in three 24-ft. Dorr vats before entering the cyanide plant. MKT.M.I.1 RGK'AL IlKSlLlS OF FKFJSKNT MktiioDS Gold, Silver, Co|i|)ei-. Lead. oz. oz. '/« '; 0.1 :!5.4 0.25 0.7 2.0 r.Ton 2.0 10.0 0.03 is.o 0.15 0.4 The feed lo the stain|i-iiiill assiiys The concentrate ass.Tvs The tailing, after concentration, assays The recovery therefore is: gold, lead. 45'.; . Necessity kor Better Concentration. The above data show that a little more than half 'lie gold is being fecovered in concentration, t)5 : silver, 48 ; copper, 35 ; and I: 92 rHK FLOTATION l'KOCF> iuul tliiit llir rci-()\rrv (in sil\rr. Irail. iiii.l ropjirr is loss IIkiii iiiilf tho L-(iiit(-'iits ill tile original nvv. Tests iiKJieati' tiiat mure tiiaii ltd', of the niet-ij in tlie oiiginal ore (leeiirs ill tile form of sillpliides. Ileiiee iialf of tile nietallie sul])iii(ies of tile orisrinai ore enters tiie eyuiiiiji' i)laiit. Tliis is um' siraljje for tile following' reasons: 1. Tile extraction of silver from swliiliide metals is ])o'liisc'l licftirc tlic t'rotli began to run out. Tliis jn-ocess was rcijcatcil, on the tailing, fniiu live to seven times. Several hundred tests have been run, all possible variations of conditions being tried. The results of the tests led to tlie following conclusions: 1. All ores from tiic mine may be treated by flotation. Semi- oxidized ore from one level yields a tailing a.ssre for dotation is vital; at present the tnhe-niill. hall-mill, and dise-enisher hold the lield.— KhrroK.] 7. The hest flotation asrents. so far tested, are pine-oils. Low- jiraih' pine-oil -rave as jjood resnlts as the hi<;her-jrrade varieties. S. S. pine-oil. of the (ieneral Naval Stores Co. (cost 26e. per jial.. f.o.ti. factory I has iriven exceptionally f^nod resnlts. h'or tin hest woi-k in flotation it is neee.sstiry to have this o'\\ i)re.s».'nt to the exten! of O.t) Ih. i)er ton of ore. In aetiial plant-praetieo. where the water is returned afjaiii and afjain to the top of the mill, the consnuiiition of oil will j)rohalily he alioiit [ Hi. ])er ton of ore. This oil wdl eost. delivered, 8c. per pound. I'iiie-lar oil is much cheaper. It i>;ives j;ooil extraction, hut the •rrade of concentrate is low. Cresylic acid, when used with ])ine-oils, increases the extraction about ) oz. silver per ton. This hardly pays for its use. 8. In the lahoralory tests the <.'rade of concentrate was low. averas;in;_' 200 oz. silver ])cr ton. This concentrate cotdd he raised to ]10() oz. h.v re-t;-eatinj; the concentrate by flotation. it. Cyanide tests, run on tailing from the flotation tests, produced residues ii.ssayiii in.jui-ious effects of calci\im sulphate lias yet bee:, liiscnvered in the tests. TVlii!- the d!!!!iii •;i!li!!f IS wnsUcd ill fj'OK!' w:!*:'!' \'.:<.\\' :: A s/;:i times, before being tivated by flotation, the results of flotation an' as satisfactory as is the i>ase with mine-ore. However, a plant for II.oTATKiN IN A MKXICAN Mil. I. Il;") wasliiiij; tlic liiiiiip-tiiiliiif; woiilil Ijc inui-c fXpcii.sivL' than tii'' small tonnage of this material warrants, and tlie upcratiiin of such a plant Wdiihl necessitate tiie waste ol' more water than is availahle. Sonic itlici' method of renderinfr the durn])-tailinfr susecptihie to flotation may he d( vised; Imt the small tonnaf^'e does not warrant any extended investisjation. Tiie hest. tiling' to do. especially at the start, is !o send the dnmp-tailini^ dire<'l to the cyanide plant (after enncen- tratintr tiie pri'oiind sand on Wijfleys) as at present. 11. As a result of the lahoratory cNperiiuent, it wa.s deeiilcd that fullsizcd tests should he conducted in the plant on run-of- inine ore. I'l.AN'i' Thsts. h'or this iiurpo.se. there were set aside for the flotatiou circuit: one battery of five stamps, two Wilfley tables, one elas.sitier, one tube-mill, one 24ft. settler, and one pump for returning the water from the sottling-iaiik to the head of the mill. A fiotation-eell of the pneumatic type was first tried. When treating 20-oz. heading this inaehine produced a 290-oz. concentrate and a 15.3-oz. tailing. This was far from satisfactory. Another machine consisted of a series of mechanical-agitation chambers, alternating with a series of settling-chambers. From the start, this machine has given excellent results. In spite of many mechanical difficulties, and trouble with inexperienced operators, the tailing from the plant has iveraged but little above 5 oz. silver per ton. and the concentrate has averaged above 600 oz., without re-concentration. The chief weaknesses of mechanical agitation, as ascertained in this mill, are as follows: 1. The complex system of shafts and counter-shaft, with the coi'rc.sponding drives, bearings, etc. 2. The difficulty of adjustment; any slight change in feed necessitating a change in the valves of each chamber. :!. The difficult.v of the passages Iietween chambers becoming clogged. Si'BMKRGKD AciiT.vTiox. It has been attempted to evolve a flotation machine to overcome these weaknes.ses, and at the same time give results as good as the mechanical agitation plant. A small machine (capacity 15 tons per day) has been constructed, and this, after many alterations, has yielded a 3.7-oz. tailing and a 680-oz. concen- I I I- novel principle of flotation — that of submerged agitation — the mixture of pulp. oil. and air being violently agitated in a partly 96 THE KI/)TATION I'ROCKSS rU>svi\ (•liaiiil..T, under tlie liyiln.sti.lii- jmi'susiiiv of s.-vcral lr..t o|' |>ill|) ill the M'ttliiijf-clijiMiliiTs above. In roust luctioii. this iiiacliiiic is siniplrr than llie iiiai-hin,' usin^r meclianical aKJIation. It ••(insists essentially of a V-shapeil liox or trougli, divided into eoiii|)artnients liy a series of vertical partitions. At the hottoiii of i-aeh jiartitioii is an a^'itation-ehaiiiiier. Airilation is supi>lied hy a paddle-wheel in each ehainher. All the paddle- wheels are mounted u])oii a sin«l.. horizontal sliaftiii>r. which passes the iMitire lent,'th of the trou^'ll. leaviiif,' tin- end partitions throu^rji sturtiiifj-ho.xes. The pm1|) enters each asitation-ehainl.er throiii;li an opening' arouiKl the shafting, and leaves the agitation-chaiiiher throuf;h an adjustable ajtertiirc, at a slif.'ht distance from the shafting The atritator thus acts sli<;litly as a centrifuKid pump, overcoming' the friction loss in the imssajre from one coin|)artiiient to another, ami keepins: the heif,'ht of the pulp the .same in all the settlinfr-chambcrs. The adjustment of the aperture is arrans^'cd to increase or dcerea.se the centrifugal force. This adjustment oeca.sions much less diniiMilty than is experienced in mechanieal a^jfitalion. where the How from one eoiiipartmeiit to another is merely throttled. Also, ill the new plant there are no pipes to become clofrfred, the pa-ssa^e of pulp from one cell to another being along a rapidly revolving shafting, which keeps all material in suspension. The concentrate overflows from both edges of the trough, thus being removed more promptly than in a plant using mechanical agitation. Further tests with the small machine are being made, and a larger machine (cajiaeity 40 tons per day) is being constructed, for thoroughly testing the princi|)les involved. The 40-ton machine will be constructed witli the idea of using it for re-concentration of the concentrate, should a full-sized flotation plant be installed. Si.Mi'LK Mkcii.vnical A(iiTATiON. The maeliine ha.s now been operating intermittently for a month. During that month it ran si.x da.vs continuously, treating 2.") tons of 29-oz. pulp and producing 6.4-oz. tailing and GOO-oz. concentrate. During the first five days of the following month, careful tests were run to compare flotation results with those from current concentrating practice. The following tables give the summaiy of results from these tests. ^rii.i.-TK.-^T.-^. Flotation v. I're.sent (■'oncentration Practice. Flota- tion plant takes 25 tons per day of mill heading after being crushed to 20-!!!es!! bv St.-iiiins ! a tube-mill. . T,,,.,.<.^. Oil ^r :iiit-_\.i, aiiti ;)asN;-i! ;iiriiugii KlnlMhiN IN A MKXICW Mll.r Ml I \r I I Kc.ic \\. lU ^1 I'm Ton ok OnrdixAi. Oiu. I'^i Kioi Tong. Mill-heading l.OOOO Wiltley lonreiitrato 0,i»313 Wlllloy tailing M.9tiS4 F'lotation concentrate rt.0207 Flotation tailing n.'.'i;" Cyanide residue Cyanide Inillion Licji inATio.Ns* Wilfley and flotation (oncentrale, tons 0.52 Gold, 0.12 oz. at $20 $2.42 Silver, 35.10 oz., 95^'f> = 33.343 oz. at 50c 16.t;7 Copper, 37.- - 0.3 = 2.7^', ; 2.S1 lb. at S.2c 0.23 Lead, ll.S^'c - 1.5 z= I0.3';'c ; 90% at 3c 0.2S , J Vssay , , — Conti •nts Gold. Silver. Gold. Silver. 0.125 39. SI 0.125 29. SI ::.o7o fit;;!. 27 0,09fi 20.70 O.ICiO 19.70 0.029 19.05 1.190 »;92.7S 0.1125 14.34 0.001 1.9S 0.001 4.71 0.001 1.00 0.001 0.95 0.003 3.7i; Less haulage, freight, and treatment, at $19.t;7 per ton $i.o2 Less taxes, commissions, etc, 7.44%. 1.4,-, 119.01 2.47 Bankable funds from concentrate per ton of ore $17.14 Bullion from flotation-tailing, per ton of ore, 5.56 oz. gross: Gold, 0.003 oz. at $20.67 $0.06 Silver, 3.76 oz. at 50c 1 ss Less haulage, treatment, l.OSc. per oz. Less express, duties, etc., 7.8'', .$0.06 . 0.15 $1.94 0.21 Bankable funds from bullion per ton of ore •Throughout this article values are given in U. S. Currency. Products Pkb To.n- ok Okicinal Ork Tons. Wilfley concentrate.. . .0.031:! Flotation concentrate.. 0.0207 Average concentrate. .0 0520 Bullion Gold. Oz. 3.07 1.19 2.327 0.003 Assay. Silver. Copper. Oz. %, 663.27 2.75 292.78 3.36 675.00 3.00 3.76 Lead. Zinc. 12.00 11.55 11. SO 12.7 13.9 13.2 $1.73 Insol- ulile. 24.5 34.3 2S.4 Phe-sent Practice. During tlie five diivs tlie flotation test was being run. the rest of the mill received 160 tons per day of the same grade of niiii-heading. This was treated on VVilfle.v and Dcister tables and the tailing re-concentrated on Wilflevs and vanners. |! 08 THE FLOTATION I'KOCKs^S MiiMiiiK.K vr Rh^iiis. I'm Tus m Ouk.inm Okk TOIIH. Mlll-lu'a(Jiii^; l.t.'iiOdii Stainp-niill coiifcnirati'. . ii.0;il!.'iO V.illley rc-concpiitiale. . (l.UO:!?:, Vaiint-r ri'-conci'iitratf. . . .O.oriocii Tailiiif? ii.i.triM.", lU'Hidue il.nr)Sl."i Dullion Bullion. 24. SS oz. ktobs: koUI, (1.0427 oz,; silvfr. l(',..-,0 oz. |ifr ton 1,11(1 Hi \ I KIN, I'KIl Ton Ol OllK.INM, UUK Concentratp, tons (i.i>4i)>:." Gold, 0.0777 oz. at $20 $1..-,.-, Silver, 20.24 oz.; 95',c at .'iOc !i.t;! Copper, 2.41',^-0.:! = 2.n';; 1.73 lb. at ,s.2c n.u Lead, '.Kl'c- \S> = ^.2''r: 90-; at :ic O.IS . Assay , — C'ontt •llt.S - Gold. Silver. Gold. Silver. 0.125 39.81 0.1250 39.81 1 .",»:!o ulS.Oo O.OTOfi lS.94 1.760 2Nt;.44 0.006H 1 o,s 0.7S0 370.02 OOOO.i 0.22 0.0,~)t| 20.40 0.0473 i!t.r)7 0.0II4S 3,12 O.OOlf. 2.9.S 0.0427 Ui..-,9 Less hauluRe, freight, and treatment, at $19. (17 per ton $n.N(i Less taxes, conmiission, and ex|ietise, 7.44' ; O.m; $11. IS i.oi; Bankable funds per ton of ore Bullion from current tailiuK. 24. SS oz. gross: Gold, 0.0427 oz. at $20.(17 Silver, 1(;..",9 oz. at r>Oc $9.S2 ^O.SS S.29 l.ess haulage and trealmenl, at l.Obe. pei Lnss express, taxes, etc., 7.)i':'r Bankable funds per ton of ore HitoiMtis Pkr Ton ok OuoaNAr. Okk . $o.2ii . 0.72 $9.17 0.9S 5n.19 Tons. Staniii-mill concent rate.. O.03(i50 Wilfiey re-concentrate. . .0.00375 Vanner re-concentrate.. .O.OOOfiO Total concentrates O.OlO.So Assay. In.sol- GoUl. Silver. Copiier. Lead. Zinc. ubl". Oz. Oz. 'r Tp '^'r 'r 1.93 olS.OO 2.3(; 10.40 12.9 24.50 1.7(3 286.44 1.03 3.37 (i.O 4.^.2S 0.78 370.92 1.00 5.86 4.7 .•;t;.22 1.90 496.00 2.41 9.7 12.1'. 27.00 Costs. Labor and rejtair cost.s will remain about the .same a.s now. Two high-class ojjerators in the present re-treatnieut I'.lant ..'111 » iiji 1 . - .t /-•..• ^_» '.*.;:; :;f ri."];i;i:"';; ;;\' ; lirir t'liCJip fipcrilturs ill TuC norriTlOit jUciiiT. Power consumption will be increased about 40 hp. This will cost 5c. per ton. KIiiTMliiN IN \ MKXICW Mill. 99 ( >il .(iiiMiiiiiitioii Will 111 jiImhiI t II). |pt I 1(111 III (ire. ill).@8c. = 2c. •If toll. Tiif tiiiiil iiicrca.M' in the fnsst «( eoiiccutiatidii will tlierct'ore be nlxiiit "c. per tdii. Till' picsiiit lyaiiidc (•(insuinptiim pep ton (if on- is 6 11)., of which 2 II). is int'ihaiiicaJIv lo.>*t. Small lahoratory tcst.s show that the chciuiiiil (■()nsuin|)lioii of lyaiiidc when Hotatioii-tailiiif; is tivated, i.s only 1 111, jxr ton of oir. This is .'( II). less than the consunip- tioii when 1 HIT. lit tailiiiff is treated, [f tiiis result is .sustained in actual plaiit-|)iactice. the saving in cyanide alone will amount to ■i X I!'"- — " '>7c. i)er ton of ore. The present cost of i)recipitation and meltiiifr is 2.56c. per tine ounce. In present practi(>e Ki.ti fine ounces are i>roduced per ton of or<.'. When flotation tailing is treated, only .'J. 7 oz. are produced per ton of ore. This means an I'.xcess of 12.0 oz. produci d in present practice: 120 X 2.060, = ;{;{('. i)er ton of ore. Fin AM ur, Sr.iiKMKXT Flotation v. I'le.sent Practice, Per Ton of Original Ore. Present practice. Flotation. Bankable funds; niarlu'tinR (onceiitrate $9.82 $17.14 Baniiable funds; niarlcetinK bullion S.19 1,73 Increased cost of concentration 0.07 Decreased cost of c.vanide 0.57 Decreased cost of nieltiUB and inecipilation 0.2S $1S.08 $19.72 Increased luoflt i)er ton from flotation, 200 tons |ier day ;it $l.t;4 = $:l2S increased inoftt per da.v or $9840 increased profit per month. The above is calculated on the ha.sis of results from a single mill- test of 5 days' duration. During this interval the heading to the mill and tiie residues were e.xcessively high; indicating a greater advantage in favor of the flotation plant than is actually warranted. The estimate of probable profit may be revised roughly by using the metallurgical results of the pa-st two months for the basis of calculation.;. During two months the heading to the cyanide plant has averaj.'ed 17.8 oz. silver, and the residue has averaged 2.75 oz. per ton. The residue from cyanide-flotation tailing would as.say 1 ;;.:. ]/ir ;;>;;. ii;is iruiicaiio an iUOi ea.-M.-ii t.\iraclloii oi' 1.75 oz. silver per ton of ore. 1.75 oz. at 41c. — 72c. increa.sed proiit per ton. The indicated decrea.se in cyanide consumption (as determined 100 TriE rr.oTATioy prockss solely ill tlio laiionitory i is :> Ih. per ton ol" ore. Kcducinsjr tliis to 21 X I!l<'. =^47c'. per ton of oro. The (l('crcii.sc(l cost of pivcipitatioii and nirltinf; may he tifrurod as follows:: Cost of nrccipitation and nitdtinfj, por tine ounce, has l)C(>n 2Af. The decivasod production of bullion. dui> to flotation, would he 11 oz. per ton of ore. 11 oz. at 2.4e. = 26.4e. When fixed charges are considered, this .should he redrced to 20e. per ton. When tlic ])rofit fro;ii marketing an increased amount of lead and copper Is halanced afjainst the increased loss occasioned Iiy marketing the silver and gold as concentrate instead of hullioii, thei'e is a deficit of 17c. per ton of ore. Tiie matter may hi' summarizi'd as follows: Per ton. Increased extraction $0.72 Decreased cyanid" -Dtisiimpiion (1.17 necrei.Kod cost oi procipitatinn and melting 0.20 $1.39 Increased cost of niarl^etins; 0.17 Protits per ton of ore $1.22 The average tonnage of min"-ore for the past two montiis has heen r>7()l tons. Hence the indicated increa.se in monthly profit would he 5761 X $1-^2==. t7()28 42. I.vsT.viJ,.vn(».\ UP Flotation rr,.\NT. Sliould a flotation ])lant be installed, operations in tlie stami)-inill will continue as at present; tiiough it may be deemed advisable, after the flotation plant is ruiuiiiig smoothly, to eliminate concentration in the stamp-mill, and dej)end upon the flotation jihint for all coiu'cntration. Ke-concentration of current tailing on vanners and Wilflcys will be discontinued from the start. The dump-tailing will be treated as at present, with the exception that this material will enter the plant only in the day-time. One tube-mill, one classifier, one elevator, and the re-concent rating AVilfley tables will be kept sepai'ate from this circuit, which will be in cyanide soluti(ui. All lime for the cyanide i)lant will enter this circuit. One of t!ie 24-fl. tanks and one of the pumps must bi' res^'rved for-the dump-tailing circuit. All the tutie-milling ot' current sand tailing will be ihuic in niill-wMtcr Instea.il of cvanide solution. The ground sand, together with tlic cuiTcnt slime, will be settled ill two of the 2! ft. thii'kening-tanks. and will then enter the flotalion FI.UTA rloN IN A Mi;.\l('\N .MII.I. 101 l)laiit. From the flotation phuit, the tailing will tlow to the tv " ;j:J-tt. thiekeuiijg-taiiks. The thiekeiied piilit iVom these tanks \vi' be de-watered and wa.shed in the vacuuiii-Hltcr before entering the eyaniili' i>lant. All lime I'or the niill-eireuit will be added as an emulsion t'> the flotation-tailing launder, where it will be under direct eontrol of the tlotatioii-()j)erator. The water in the 2.'i-ft. thiokening-tanks will contain about 0.4 lb. dissf)lved lime per ton. This is ample for go(Kl .settling The overflow from the.se tanks will be reduced, by consumption, to about 0.1 lb. per ton. This is sufficient for fair settling in the cone-bottom tanks of the stamp-mill. By the time the pulp reaches the 24-ft. thickening-tanks the lime will lie reduced to O.Oli 11). per ton. This low lime will be e.\tremely detrimental to good settling in these tanks. IxsT.\Li,.\Tiox Kkc^iikkd. The matter of supplying proper settling and de-watering facilities will be the most serious and most expensive ]iart of the installation. The two 24-ft. thickening-tanks, to be us<'d in the flotation-circuit, must be triple-decked. It will also probably be found neces-sar.v to double-deck the :i2-ft. steel thickening-tank. The work on settling- tanks will cost a'oout $6000. Hy inerea.sing the settling capacity, the pulp will proliably be settled to a sufficient thickness s,sii<' \\n- XiiVfiiilicr IDli:! df the Cftlifnniia .Inin-iinl nf T< iliit'ili,!/;/ tlicri' api)i':irnl ;in artirlc (|csy tlircr sciiidr studciits in tliu I'liivcrsity of CaliforiiiM. Tlic arlii'lr is ciititlcil ■ Kxpfriiiu'iils on the Klmnru Prociss of Oil Coiiri'iitralion' ],y \V. I-', ('oprlaiid. Drurv liutltT. and .las. 11. AVis.'. At the outset tlicx- .state: ■"The i)rores,s depends upon the fad that iiiinerais with a metallic lustre, when treated in the form of a wetted pulp, adhere to oil. while earthy minerals do not. Two distinet operations are involved; first, the sejiaration of tie' inetallie mineral from the sraiisrue oy means of oil: seeond, the exfraetion of the mineral froiii the oil. '■'Ihe ideas iinderlyinf? the first operation were ])a1ented hy -lohn Timihridgc of Newark. N. J., in ]S78. In 1886 Carrie J. Evrrson, of Chiea^o, eontrihnted the idea that the eoucentrafion was aided by the presenee of an aeid solution, and i)atented the same. Hut the ah.sence of a sui'c<'sst"ul method of separating the mineral from the oil prevented the ])raetieal appiii'ation of these early patents. Hurii- iiifr the oil was tried. Imt this left a difficult residue to treiit, ami the large eonsumption of oil madi- the method too expensive. Settling the mineral out hy thinning the oil with ga.soline, ether. <'arhon- hisulphide. cti-.. also proved too i'\iiensive. and it was not until July 1900 that this diffieulty was overcome, when ^Ir. Francis E. Elmore, of T,ecds. longlaiid. accoiii|)lished the separation by means of a cen- trifugal machine, similar in most respects to those used in sugar factories and in milk and cream separation. This contribution hy ]\lr. Eliiioi-e. then, made the process feasibl'\" I They give an illustration of the plant design(>il by the Oil Coii- centration Syiidicat(> and 'deseribe the operations. Their own ;\\i- I)aratus is shown in photographs and they give details of tiie tests made on various ores. In brief, they obtained the followint: results. Rxtrac- Character of ore. tion, % (JoIU-qiiartz ore Sf; Silver ore -r, ropiier-sohist taillni; Sn Molybdenite ore 7-, FROTH AND FLOTATION' 103 'I'Ikv dfsoiilx' tlif nature of their experiments and comment on tiie filets disclosed in a inosi intelli^'ent way. We (juote the salient para- graphs.] "In makin<^ a test, the ore is first crushed to the desired fineness, and the proper eharcre is thoronsrhly wetted in the solution to l)e used (usually water), thus f(U'iiiin^' a thin pulp. The oil is next added and till' whole ehartre thoroufrlily mixed This mixingr, oi- ai;itatioii, <'an )»■ dune in two different ways: The charge may be agitated very grnily. tlie oil licintr kept in a single lake, and broken up as little as po.s.siblc consistent with a thorough contact of pulp and oil; or the charge may be agitated so violently as to dash the oil up into a foam or froth, full of air bubbles: thus a very thorough contact of oil and pulp is obtained. •••#•• "Thi'ee methods of mixing may be used. 1. By inverting the tube several times, thus allowing the ore to fall through the oil. 2 Hy i-otating the tube in a horizontal position, thus throwing till' pul]! up on to the surface of the lake of oil. :i. liy violently shaking the tube. ' lius producing the foam effect* or at least shattering the oil into small globules." • ••••• "The solution tised in the concentration is a matter of some im- poi'tance. Water is. of course, used whenever jwssible, but certain other solutions have important advantages. As before stated, an acid solution is found advantageous. Tt cleans the metallic surfaces by dissolving the metallic oxide coatings that may have formed on tht'in. Tt inrrea.ses the specific gravity of the solution, and it aids in produi-ing ihe foam effect, which is due to the generation of certain •rases. As befori> stated, the specific gravity of the average oil used is about O.f) and water 1.0,t leaving a difference of about 0.1 for buoy- ancy or carrying capacity of the oil. The idea at onc<' suggests itself that if a denser solution be used, the cni lying power of the oil will be increased correspondingly. A .salt (NaCl i solution, for instance, gives excellent results. A saturated solution of NaCl at 20T.. containing about 2"';', NaCl, has a specific gravity of 1.204. This gives a difference of 0..S between the specific gravities of the oil and of the solution, and a carrying capacity of the oil tnrer-Toiu glertter iiinn Wiiii nfiier ,ui)iie. "NoL oiliv (iocs it I •[The italics in all these quotations are ours.- — EnixoR.l i[In the original It is .1. — Rihtor.I 104 THE HX)TATIOX I'KOCE>S f-'iv.. tr,,,,,,.,- Inui.vaiiry t,, ih,. ,,i|. l,ut ,7 <,/.„ „„/.,. „u,i,ruiUu in pm- wetted. Hence if a metallic particle he thorouphly wetred, a water surface and not a metallic surfac- is exposed to the oil; and the former, as hefore stated, has no affinity for the oil. It is evident then that the water film must first be displaeed hefore the oil and mineral can come in eontaet with eaeh other. This displacement is hardly i)rob able if the water film is in intimate eontaet witlr the particle, and it seems mor(> probable that the difTerentiation is due to the fact that non-metallic surfaces are. and metallic surfaces are not. actually witted. If this be the ca.s<\ a careful study of the relative wetting; of difVercnt surfaces would be an important line of investigation. 2. The ratio of the exposed surfaee to the wei^'lit of the particle should be as larfro as possible. I)eeausp tlie total adhesive force is increased with an inercase of the surfaee expo.sed to contact with the oil. This eouditiou is best realized when the mineral breaks up int(. thin flakes. It is evident from this that a knowled','e of the fissile eharaeter of the minerals in f|uestion is important. ;i. One fundamental difficulty involved in this jiroce.ss is that it undertakes to concentrate and float .v heavy metallic mineral, and s^ink the liyrhter trangue minerals, but this jioint is Tiot necessarily t^ital to the process. It is evident, however, that the heavier the paiifTue and the lifjrhter and mori' fi.s,sile the metallic minerals, tlie better the ore is adapted to this method of concentr.ation. This is a direct reversal of the id.'al conditions for .iifr or vaiuier concentration. 4. Anoiiii-r <-haraeteristic of the process is the faet that the ratio of concentration is usually small, due to the larsre amount of <^an^^le occluded by the oil an.i .-arricd into the ronccntratcs. This ditlieulty is increa.s,( nnUn- tinn, (si„ri(illif in arlil ,,r salt snliilimis. This thmirs Ihr nil into a fruth. irhiih is hmvilit ,h,ir,i,,J irilh nir nr <,fhn- gasis. Thit r/as, of KUdTII \ND rl.dTVTIlIN lo:. (intrsi . f/ivts (I ;jn ntlji in, n asi nnlv SUS^L'eslivi' ('vncriinnnte Pimt.^d 1 f 106 THE FLOTATION PROCESS m FLOTATION AT WASHOE REDUCTION WORKS, ANACONDA By E. P. AIatuewson* iFrom the Miniiiy and Scientific Press of August 28, 191&J Till' iiiiiicriil that is two milliiuftres and undfi* in size is sent to the llanliiijje mills for re-grinding. These mills are 10 ft. diam. hy 4 ft. long, and are in closed circuit with simplex Dorr classifiers, one cla.ssitier to each mill, 6 mills to the section, and 8 sections in the establishment. The overtiow from tiie classifiers goes to the flotation division, and the classitier-siind is returned to the Ilardinge mills. At present pebbles are being used in tiie Hardinge mills, but, in all probability, steel balls will ultimately be used. \Vith pebbles the Forbes lining is used, but with steel balls in use, each mill will be fitted with a false wooden lining to ri'duce the diameter of the cylinder, and a manganese-steel lining will be placed inside of this. Ea<-ii mill ha.s a direct-connected 22r)-hp. motor. The mill titted with pebbles required from 95 to 115 hp., but the motors are madi' extra luavy, in anticipation of the use of steel balls. In each section of the flotation plant there are four iMiiicral.s Separation machines, each having M agitators and 14 floating- compartments. Below these are six Callow cells for cleaning the concentrate. The agitatoi-s tor the AFinerals Separation machines are made of gun-metal and are driven by bevel-gears from the main shaft. (See Fig. 17.) Each machine is driven independently by a loO-lip. motor, running at :iH') r.p.iii. on full loml. The speed of the agitators is reduced to about 225 r.p.m. The produet from the machines is a tailing, which goes to waste (from this tailing, fire-bnek, building-brick, and acid-proof brick will be made in a new^ brick-plant now under construction) ; a concentrate, which is sent to the Dorr thickener-tanks, for settle- ment — tliis comes from the first three cells of the frothing-machines. The rough concentrate from the next six cells of the M. S. machines, is further cleaned in the Callow cells (See Fig. 18). making a clean <-oncrntrate; anil the middling, which, with the middlings from the remaining five cells of the J[. S. machines, is returned to the feed of thes<' same machines. About C to S ii). or .mT i>. .•Miiiiiunic acni, per ton of iiotation- ♦Manager for the Anaconda Copper Mining Company. KLdTATIlIN AT TIIK W AMluK KKDICTION \V(>UK~. \N\((lM.\ 107 ll),S Till", ii.utation rii(Mi:ss t'ri'il, l>, use I, loi,'i'tl|iT willl I Wll li) tliri'i' poUlnls of kiTllslMll' sludj.'!' in'id aiul t'roiii DMc-liiiir to one ixmiid (■!' wood-croosote. A |)ortioii oi' the wood-crcosotc is added to tlir head of tlie IIar1I()K HKDI'CTIns \\iHiK>, \\\'i)M)\ IH!! 110 TMK FLOTATION TKOCKSS In tlir iitli.r. For iiislaiicc. tlic No. -2 s.vti(.ii t<( tlic nill w.is Jii (iprratidii y jets of ec.mpressed air. It was thus early reeopii/,.,1 that flic Imhhles of froth noticed in tin \vct-(!oiic<>ntrHtion o|>cralioiis wen- due to the aeration produced hy violent atritation. resultiiifc from mechanical implements moving rapidly in water. In these experimcins a metallic froth or scum could he produced and recovered assaying 2C, oz. silver, W', lead, and L'L"; /inc. The appliMiicc employed is illustrated in rig. ]!», FlO. 19. APPARATU.S lOB KXPEBIMENTS ON KROTII. [Up to that time the lead concentrate was the only marketable proiiuct from the ordinary water concentration. Besides calcite, the ore contained a good deal of rhodonite and garnet, each of which ha.s a si>ecitic gravity close to that of blende. Thus water concentra- tion could only yield a quartz tailing and a leady zinc-rhodonite- garnet middling.] Preliminary Test. Pearly in ino,3 an exhaustive series of labora- tory tests was made on the lead by-product by flotation methods, using heated sulphuric acid and salt-cake solution. These tests 112 Till'. KI..)TVT|iiN I'UiMKss viildfd sdiii.' .sli^'hi iiifiLsiiiT 111 sui'i'i.ss on iiialriial s|nriallv |»iv|)aiiMi. that is, oil jjniiiiy niat.Tial I'mm uliidi Imtli the nnivsi- and liiif liad Ikiii •■liMiinat.cl. I.avmt,' it r\,n]y si/fd. Crrtaiii cla.vs.'s of ih,' iiialirial produced lj\ our miils contaiiii'd .smii a iar>;f proportion of iarl.onat.'s— siidi as carlionalis of iiiarijfaricsc, linif, and lead- that no HotatioM eoiiM lie secured e\(i>pt by a prohiliitive eonsuiii|)tioii of acid. These- tests uere ear-'fullv made, hut the l»est work done in tlie ialioratory was not equal to liiat liein>r secured on a I'onnnercial scale in the existiii-,' niat,'iietic plant The tests on these llnlatiiui iMclhods were conduclel in pans or vessels worked on the prM|,.ipl,.s of spit/kasleii, follouirif,' the lines of Potter and Dilprat. \\< lirsi ai>i)aralns was islructed so that the li(|uors could he raised in teitiperature hy liic ai)i)lication of direct heat underneatii the |)aii ; I'l'l i" the later tyi)es the teMi|)eralure of the lirpior in tiie pan or si)itz 1)()X was niaintained hy the injection of live steam into the storairc tank. In noi f these tests was aj;itation employed, the material to he treated heintr fed practically dry on the surface of the liipior in a rci^ular stream, and the heated liiiuor added through a pipe diseharf,'inf; near the hottom of the vessel, and given an upward inclinalion in order to produce an u])-eurreiit in the ho.x it.self and a gentle overflow at the lip. A still surface was imperative in this operation, and it was eipially evident that the operation de])en(h'd largely I'or its success on surface tension of the liipior. after the gas evolved hy the action of the acid on the mineral earhonates had raised the particles. This surface tension was increa.sed hy the density :ittained in the one case hy the salts formed from the mineral and gangue through the action of the sul|>huric add. and in the other hy the addition of salt-cake. In all tlie.se experiments the licpior was returned hy the ordinary type of air-lift, using compressed air at ahout 70-lh. pressure. These experiments dednitely demonstrated : 1. That there was a limit to the size of the particle that could he buoyed Up. 2. That any material below a certain size, no matter what it.^ character — whether gancue or mii\eral -floated, owing to the density of the solution. •"?. That if the finer particles of gangtie were not eliminatci] hefore treatment they wotild be floated with the mineral, and lower its vnliie in metnls to sncn an extent S.i to m.lke it ii;i!n.Tr!ci^t;d'.!c Slime, whether existing as a by-product of the ordinary wet-mill concentration or subsequentl.v produced in preparing tailing for :j^^ ■.. 1 r,(PT\TliiN AT Till, ( KNTKM, MINK, HHUKKN Mll.l, ll;i tnatni.'iit, l.iilkcd so Utrarly iiiiioiij.' tli,. total iriatrrial availalil.^ for n-tr,.atnu'iit that any pro-'css that lail,.,| ii, this dinctioii was too limiti'fl in its wop,, to \,v of iiiiK'h vahic to lli.. Central iiiiiic. As far as unv process up to .late was .•onceriicd. slitni' had to lie reiranled as of no valiif exeept in so far as it was availahle for siiieltintr. Th.. Hroken Hill I'ro[)rietary Co. had used a eousi.lerahlc •luaiitity in this way. and ha.i diseov.red that roastini; or sin- tPrinir the slime in open heaps after hri(piettin>r ^'ave a fair [)ro(lPet valiial.le f(,r snieltin(r. ..; ,^ i ,|,.„| „f ,i„, sulphur an.l a fair proportion of the zinc havini; hccn driven off. The Suli)hi(le Ccrporntion also souplit to inak.^ its slime avaiial.le hy this m.^ans, hut it Wius proved that the losses of metal were too ^freat to .ju.stify this method of rendering the slime amenahle to direct smelting. Cattkk.voi.k ok (Iimm i.atio.n I'hocks.s. The forepoiup experi- ments were aliandoned on account of information received from London. C. F, Courtney, wlio was in Knsjland durinkf the year 1002, adviwMl that a discovery of eonsideralile importance had been made: that laboratory trials gave every indieation of success on a larprr scale: and that the process was so comprehensive as to include the finest slime and varying coarser sizes of particles up to \ mm. diam. This wa.s .subsequently known as the Cattermole or granula- tion proc'ss, and eonsistether emulsifying agent, so as to agglomerate the oil-coated particles into granules. Thi' oil was thus empi 'yed in a state of ennd.sion in water in the pri'senee of an emulsifying a^ent, such as soap. After agitation the mixture was pas.sed into an up-current separator or eliussifier to remove the lighter non-oil-coated i)articles from the agglomerated mas.ses of oil-coated particles. The lighter sand having been eliminated, tlie pulp passf^d to a second series of agitators to increase the size of the granules, and thence to a W'cond classifier for the removal of the heavy sand. From the bottom of this second clas.sifier some granulated concentrat.^ was recovered, but the heavy sand from the overflow also carried over, with the up-currc.it. a large amount of granulated mineral. This mixture of gratudated mineral and h^avy sand pa.ssed then to a Third series of agitators, and thence to a shaking table, where the granulated mineral, rendered more buoyant hy directing ipts of compres.sed air onto tlie surface of the moist pulp, was buoyed to the .surface of the water and floated off the bottom of the table, while the gangue sank and was delivered over the end of the table. 114 THE FLOTATION rROCF.Sri III order til trivf lliis i)n>cfs.s a thoroiijjh trial, a luodrl plant was soiit from Kii;,'laiul ami urcLted on the mine early in 1904. (J. A. Chapman was specially ajjpointed to conduct experiments with this i)laiit. and started a lonj,' series of tests early in June oi the same year. It was (piiekly demonstrated that the process was capai)le of makin-; liiKh recoveries of all the three metals from the very finest slime, whether taken from the current work of tlie mill oi- from old accumulations, and also that old t;iilin>r oi- new crude ore were ainenable to treatment when crushed to a jjiveii fineness. The largest size of particle that could he recovered was ascertained to be about \ mm., thus conlirmini; the London woi'k: but it was found that results improved with a decrease in size to impalpability. Ill the eai'ly tests by Mi-. Chapiaaii, emulsions of the heavy oil of petruleuiu were used, but the cost was excessive, aim it was found iinpos.sible to treat slime successfully. Emulsions of fatty acids, and also soft soap, were then tried, but proved i)roliibitive as to cost, except in tlie case of o ie acid. Oleic-acid emulsion was found to act rapidl.v and etfectively on crude ore as well as on all lead by-produi'ts, includinn; slime. Mr. ("hapman's work on oils and the results obtained by him with the model plant usinrr the grranulation process were satisfactor.v, but it was thought wise to have these continued by an independent chemist, and therefore ,1. C. Moulden. the company's chief metallur- gist at Cockle Creek, was called in, repeated the exjteriments. and amply eonlirmed ^Ir. Chaiunan's work. Later it was found possible also to reduce the )|uantity rl oleic acid, as was jtroved by the follov iiifr tests in December "l!l04: Material ust'd was ciMished tailintf mixed with slime. Test No. 1. ;{..")'■; oleic acid on min(>ral and f*.?")'',' sulphuric acid circuit. The cost of emulsion in this case was 10s. per ton of ore. but the renalts were excellent, the concentiate lieing rei-overed as partly granulated and j^artly float or froth. In test Xo. 2. only 0.75';; of oleic acid with th(> same ((VTo'/e ) sulphuric acid circuit, in which Ciise the <'ost of emulsion amounted to 2s.3d. per ton of ore. the results being excellent, with idl float coneenlrate. no granular ma'erial being formed. This test took considerably longer in agitation. EiuccTioN- (IP Lah<;f. Plant. Mr. Cliapman's tests, and their ft'as n)){;tin*'ii tli.'it wduM. witii siiitaitic ni'raiigomonts fui- cnisliitiff. FLOTATION AT TllK CKXTHAI. MINI;, BHOKKX 1111, 1. 11.') efficii'iitjy handle the wiiole of tlie by-products of the -vet mill, including slime. It was accordingly decided to erect a plant on the lines of the model, with slifrilt modifications a.s dictated by experience, capable of treating 100 tons per day, operating on a commercial scale. It was clear, from experimei-ts and oliservations. that the time of agitation was a factor in tiie aeration and oiling of the mineral particles. Therefore, reckoning [ 'im ijic size and capacity of the mixers in the model j)lant, a mixer was built of the following dimcn.sions: ."> ft. deej) and :$ ft. diam., with a \\ooden stirrer 2 ft. 6 in. diam. at bottom placed vertically and made to revolve at the rate of 350 r.p.m. Experiments with this one mixer unit indii'ated that, to make the treatment continuous for the stipulated 100 tons i)er day, it would be necessjir>' to have for the first unit a series of six mixers in order to allow of the proper cleaning of the particles and the thorough aeration of the whole mixture before the discharge of the material under treatment from the last of the series. Tiie mixer was of the core-stirrer tyi)e. Accordingly, the plant was designed on these lines, and con- sisted of: 1. Grinding ap])aratus. 2. ^■at for emulsifying various oils, •i. Set of six mixers in series. 4. l'pca.sts for separating .sand and float. 5. Second set of mixers for further aeration. 6. I'pcasts for further s<'paration of sand and float. 7. Third set of mixers far re-aeratioii. 8. Wilfley tallies for the separation of coarse sand from granu- lated, sulphide. Early in 190.") the construction of this plant wa.s commenced; it was completed at a cost of £] 1.000, and .started work in July 1905. The method of treatment adopted was on the lines of the tests made i'l the experiemental modid plant, and may he briefly described. See Vig. 20. The ore, reduced to a suitable fineness, was elevated to a ho])per at the top of the Iniilding and id into No. 1 mixer, where it was agitated with the solution, the emulsion (previously j)repared on the bottom floor) being added at t!ie .same time, together with further addition of i VI, 11 ni(iuieu. 1 lie leed iii ground maicriai and tne le circuitdiqiiiir and reagents was maintained constantlv lUi ■I'lIK ri.iiTATlciX l'li()(K>S iiiiii rcguhirly. Aftrr passin^r lliri)ii.u'li tlic first set nf six niix.Ts a pulp consisting of jrniuiul oit, acidnlaicd wat.r. an,] .iiiiilsioii was j)asse(l to a iiydraiilic-si/ini.' a])pliiiMcc known as an upcast. wIkt" the slinic-frau'.'iie was cliininat.Ml hy ovcrtlowintr. Tin- lialaiirf of tile MMxtnn- was passed into tile second siM ot' mixers, liejrinnin^' with X". 7. where more eiindsion and snlpimrie acid were ad(h-d if necessary. The afritation and aeration were maintained and tiie imiIi) rj-- I ^^ : "-'^<"( l J T I LCm:'^ rcuR ■iimrt-. ll A — ^ .,^^-;:=r::d_J —^ -|&*1 ^\ F R 5UMP^ 1 Fi(i. 20. inK KXTKRIMKNTAI. MeUKI. I'J A NT. dis,-har!.'ed fiom .\o. I» into anotiier upcast, wiier.' further slime- jran-ue was eliminated hy overflow. The haiance of the material was then i)assr with ih,. sand, but tloatd inniiediately under the intluenee of iJufTs of air 'supi)lied throufrh a pipe l;iid lentrthwi.se ami close to the tahh". and then floated off with the froth <'om-,.|itrate. 'i'he san.i was delivered toward and at the end of th,' table, thus ri.ilTATIdN M TlIK CKNTHU, .MINI:, liKDKKN 1111. i 11 exactly reversiiif; tli.' it'lativp positions of coiuvntrate and tailing as tmlinarily oi)taiiiril if workinj? hy fjravity eoncuiitration. Tlio sliiiio and .iid were lollci'tt'd in one rcc-ptahlc and tlie float and ^rj.nulatcd cniifi'Mtratc in another, tlic .surplus li(niors in each case flowiiijT to a coiiiinon suiii|) for re-iisc. From the tirst day of oi)eratioti the ease with which the float concentrate couhl he reeovei-ed was very sti'lkinfr; hut the separation of the "ranuiated concentrate from the coarse sand hy tabliiifr on a larfic .scale was found to lie a ver\ delicate and difficult operation, and it was at once evident that 'spitz' separation would relieve the tallies. The upcasts were also continually chokin-^ and pi-oving a soi.ree of trouhle. besides seTidintr over larp' (juantitics of slime with the eoncentrate. thus rediicinpr the f;rade of the product and les.seninfr its market-value. It was therefore decided, when the i)Iant had been runniiifj for a few days only, to construct a small rectaiifrular s])it/,-l)ox for trial. This was introduced early in Autrust 190"), the feed to the spitz-box beinp: prepared i)ulp di.scharfred from No. 7 mixer. Tt was found also, as soon as t!ie plant started rpjrular treatment, that the au'italiou was exces.sive. and mixers 10. 11. and 12 were cut out. fone-a^itators made of phosphor broitzi> were tried, then cen- trifufral stirrers, but the scour both on the stirrer and the sides of the ini.xcr. due to the impact of the sand, was so fjreat that these liail to be abandoned, althoufjh the afritation and aeration had been con- siderablv increa.sed. The spitz-box in the slime-overflow circuit pfave excellent result.s. and toward the end of August it was pos-sible to obtain the requisite aoritation by usinjif the first six mixers oidy. A fre.sh spitz-box was placed in 'he position formerly occupied by vats 7 and 8, with ar- ranjrements for all tailinfr-flows. both .slimes and sands, to deliver to No. 1 hutch of a special spitz on the floor beneath. The ob.ject of this spitz Cl-compartment'i was (11 to allow a settlement of the granu- lated material in the first compartment; ('2) to etfcct a s»>ttlement of middling for re-treatment on tables in the second: ('■]) to provide for Hie deposition of clean sand and slime in tlie third, with an un- restricted overflow for the float material. Spra.vs on the surface of the liquor, and upcasting ,iets of water, were provided to assist the operation. Various simplified fi>nns were later adopted as the process merged from partial to complete flotation, as illustrated in the ex- perimental spitz-box for the granulation plant (Fig. 211. 118 TIIK H.OTATION PROCESS At tirst tho san.i was cj.rted l.y sluiri,,- out to a daiii ; hul lliis beiiif,' wasteful of circuit-li.iuor, ,,n,i tlicivfor.' also add, it wm.s de- cided to construct saiid-box.s. throu-li wliid,. i„ turn, tho suspondrd sand could be deposited— tlio li(iuor ovcruowinjr from tliesJ .sand- boxes to be ran to the puiiip-sunq, and thence re-eireulated through tho plant. By this moans a eh.sed eireuit would be secured, and li(iuor- losses minimized. It was not until November that those sand-boxes were actually in use. Meantime, it was noted. partirMdarlv in slime- tests, that the operation was ai)preciably assisted bv laisinsr the tem- perature of tho liquor. Steam jets were, tliorefore. introduced into the mixers m the plant early in .Septend)er IDO,'). Fig. 21. KXPKUI.ME.MAI. .sIMTZ-1 Before advancing further with the evolution of the process as de- v.lnped in the first large plant, it is perhaps advisable to refer here to certain experiments that mark a most important era in the hislorv of the process. DisrovKKv (.F TIIK FmrriiiNG I'liocE.-^.s We now com.> to a stage when a remarkable development in the operation was discovered (Strangely enough, at tho same time both h..re and in the Patent Co. s* laboratory in London^, which had for its main principle the reversal of all previous oi.erafions. and consisted in the complete flotation of each i)Mrticle of min.-ral independently in place of granii- bitmg tho mineral partb-les and causing them to sink, thus not onlv revolufieni/ing th," pro,-, s.s. Im.I gieally .simplifying .•,nd cheai.enin- it Ihe dovelopuH-nts noted were mainly along tho line of decreas,.,! con- sumption of oleic aci,] or oil. for example, from 'V, oleic on ore ro- suinng n. very little float, down to 1';. .^riving pracficallv a complete float. Th<. I^illowing data from a n |M,rt furnish.,! hv A. li Hi.-i\2 t'l 32.0° Still more float 1.1 l.CG ii.:;2 t :ii.n° Float vastly increased 1.1 0.5 (1.10 s 31.0- Float vastly increased In (ncry cjiso the oleic jicid has lieeti tncasuied iii cubic centimetres and the peiTPiitapcs calculated as thoiifrli they \veif;licd grains; hut. a.s the .specific gravity of oleic is less than that of water (taken a.s 1), all perci'ntages will be lower than those actually priven. These experiments obviously proved that, the r(>duction in the per- centage of oleic acid materially altered the type or character of the oil- ing 'if the mineral particles — the higher percentage proilucing gran- ules, which were precipitated, while the lower percentages produced a mineral froth. As the qiuuitity of oleic acid decrea.sed. tlie time re- quired for oiling th.c mineral particles and aerating them was found to increase, and tnorti froth formed. These tests, followed by niiuiy others, led to Sle.ssrs, Sulnian. Picard, and Ballot's Britisli patent of April 12. irtOS, under whicli "finely powdered ore, suspended in acidified water, is mixed with a small proportion of an oily sul)stance such as oleic acid, amounting to a fraction of 1<~J on the ore, and agitated until the oil-coated minerals form into a froth, which can be separated from the gansue by flotation. Heat may be applied to facilitate oiling, and either shaking tallies or spitz-lioxes may be used to separate tiii> frotliy mineral from li.e sands and tli<> gaiigue slime." To return now to the record of operations at tlio large plant, some successful te.sls were carried out in September 100.') on dump-slime, by using this flotation method. Agitation nas conipl(>tcd in six mix- ers (using cones) in 0.6 to 1% sulphuric acid at a temperature of •'"'''"' !■' Til" ipiaiitity of oleic aeid used in these tests was from dl.") to n.L"; on the actual dry wi'ight of slime treated. From the sixth mixer the pulp passed "with a good splash" to ilie first .spit?;, and iiie residues from this "with a good .splash" t" No. 2 spitz, and the tailing from this latter spitz-box was run into lains, Tiiese and otiier experiments emphasized the import mee of dropping the pulp ? 120 THE KIX)TATIUN I'ROCESS vertically into tlif spitz to assist amiti,.,, aiwl sul,s,.,,iu.Mt Hotation aihl j)t liuatui- tlif li.HK.r to enhaiav tii,. ..ili,,,; of .niiuTal partirlrs. 'Ill- liuvr.,-oiii])artiii..nt spitz-l,ox with upcast wator-tlows -ave !'I.-H'.-. ill luni. to a t\v.,-,.ompartme.it spitz-hox witiiout upcast flow and tins, in turn, was replact-il t,y a sin-l.M onipartincnt spit/ tin' latter Ih.ii,^^ provide.! with a rijji.l flat hoard on which the I'cod was splashed to assist aeration. Conieal si)it/.-hoxes were tried, hut not jreiierally adopted. From Oranilvtiu.v to Fr.oT.vTioy. The plant had now hcen ni.inin- tor a .■nuple of months on tailinirs and slimes from various sources, and durin- this time the frothin- method was senerallv ousting the crranulatiou pro.-e.ss. until, tinally, the .superioritv of the spitz-hox and froth method was clearly demonstrate,]. The Wilfley tallies of the original plant were then dismantled to make r.Mmi lor the sand-hoxes already mentioned, and the frranulation ]f as capable of dealing with the company's ores and'bv-pro.biets and :\rr. Thapman's patent of September 1006 was taken out to pro- tect the various di.scoveries made by supplementing Sulman Picard and Ballot's patent (No. r,0.32. Vmy T'ndcr .Mr. f'hapman's patent:" 1. The ore. suitably crushed, is agitated with acidifi,.d water in the first mixer and heated. 2. Oleic ai'id is sub.sequently add, 1 in the secon.l vessel. ■3. The pulp is maintained at the desired temperature in the third and following mixers, with violent agitation in each mix,>r to insure comph't,. and thorough aeration. A s.^quence r,f operations is thus arranged by which the s,)]ution. after the secon,! au'ilat,.r. is pra,- ti.^ally or entirely neutralize,!, so that the liquor in circuit as a whole IS neutral, .'xcept at the mitset. when the ore is introduced. Th,. a,],)ption of this flotation pn.cess with its neutral li.pior al- lowed the use of iron where formerly, under the granulati,.n inetho,!. with aci,! liquor, oidy won,! or special metal ,'ould be used. For in- .sta.H'c. the original w„ _i. . ■ ..». _. . ^ .... • » ■■-.-.... w,. ai» €*ir-iirt. i ins aiso result,.,! m increas^Ml aeration, but it was found that the volume of iHinor would have to be increased to an impracticable quantity to ' I 12L' Tin; FI.orvi-IoN I'KCK'KSS jrivf tlic iirccssaiy v.|n,-ity to cjirry tin- partidrs <>\' oiv, rlc, iqi tlie risiiiiiiiip us,.,! I'or i-aisinir liiinors and iiiatiTi.-il tor- re tri.atirii.nl, th,. iiitr,),iiii.tion ,it' a .i,.| ,it' i-,Hnpri.ssi.,l air into th,' jr^t4-iy=kS=^y^.i s ■ Fig. 22. a nksi of (KMiiniiiAi. n mi-s. iiiixer-boxes, an,l al.s,i the ins,.;;i,)n of jiipi-s in the ini.\er-lio.\,.s in .smh a i)ositi,in tiiat air wouhl he edieiits, the ,',in,'hisioii was formed that the air. to lie of value, iiiiist he liiely eonuuinut,',!. tint that any ad, lit ion was ,if vidue that would decrease the ein'rpry rrquind I,) si'cure ai-i'ation liy means of mechanieal atritatioii. :\IixKi{.\i.s Si;i-.\i!ATiiiN Pi.A.NT. Til,' .Minerals Si-paralion ,-ompaiiy, owners of the froth jiatcnLs. ])ureliase,l the tailinrii of p,isitive pan that the plant wa.s alile easily I,) liamlli' ."lOdO tons ]ut W|.,'k. This p'niit was respitnsilile for llie Ireatiiu'iit ,if 7\ \T llli; CKxrii U. MINK, i;uiiKi;\ nil. I, 12;; UlaillilMllnn plMl.l, l.Hlir ,l(SI;r 1 1\„. an ;,rl,l rirrllit. Was .Miuipi,,.,! onguiiilly witli wood tliroufrlioiit wli.iv li,,,i„r circulated, and with .lry-cnishn>j? liMll-mills for ti,.. sanic reason. Later, wet crushing was adopted, hut will, a frcsh-watcr circuit, kept carcfullv se{,arato In.m tile acid circuit in uhicj, Uw a<'lual separation took place. The successful .i<.v.lnpMient of the flotation pr s.s, however, has enahled l"'th cru.shinfr and .s,.paration to he .'oinlucted in one and th,. same eircuit, and has thus greatly simplified operations. I'll.' liquor that was circulated through the .Minerals Separation plant was apiuo.ximately i>.-,,0()0 gallons per hour. During the F:n. 2:!. thk pia.nt .\t tiik ikmiiai, .mink. course ot operation, therefore, over 600,000.000 gal.— eipial to ncirly 3 000,000 tons-has passed through the V2 iron grinding-pans of "this plant without detrimental effect. \o stronger evidence could be produ.'cd as to tiie freedom of the eireuit-li.iuor from acidity Ihe maintenance charges on these iron pans are no heavier than eorresi).,nding charges on exactly similar grinding-pans in the Icad- iill crusher-section, where fresh water only is used. Following e.xhaustive e.xperiments in th,' lal.orat<.rv, various media have from time to time been used for long periods on the commercial scale, both in substitution for an.l in combination with oleic a.'id Chiet among such media are amyl ah-ohol, resin-oil. camphor-oil' pme-oil, and eu.'alyptus, with all of which ingredients trood work '■'^.' " o'><'»"HHl. Thus Nature, in chi.se j)roximitv to the vast bodies of complex ore, has j.rovided the means for tl,; concentration or Sllcli nr^ia fj\t^ +li,-. ,.^ — ..4:..l ,:i ,i» .1 * _. , ." " ' — -"-.i.-.i t;:: tji iur .viistraiiaii eucaiypius is one of the best-known media available for the successful exploitation of •viractory Australian (,res. It is of interest to note here that this V2i Tirr. FI.oTATKiN PH(((T>- '■''''''"■■'""'" •"■ "" -^I'MialKiM pn.,|u,.t ,„ ,1,, t.TMluH.nt m' ronn.lrx '"■'■' '^ ""■ '"•"■"""■ '"' " '•'-•"■'! "" tl)- < Vntn.i mi,,,. I,v m,. A„s,,-alia„ -HHalhorns,. I|..„r,v l.av..,s a,„l ,. uas als,. i„ tl,.. „„ll,„i; ph,„t „„ ""■ ^'.•""■'' '" """ '■'"■ai.vptns ,„1 uas li.st „m „ .-i ,•„„,„,.,■,.,., I siali' lor r()i]ii.|it,-;itii,ii hy t1c>tatio,i. This satisfarl,„-y sta-c liaviiij; I,,..,, ,VMri,..,|, atlr,,!,,,,, ,.„„!.! „„w ';<■ ""•'"•'i t" in,i.rov,.„.,.nts i„ .neth.Hls .,f ha„.lli„tr. a,„i, o„ s„.r.r,.stin„s "•'"" til.' o«,„.,-s of th.. pat,.„ts, it was f,„„„| that, hv .■..,„„.,ti„ir tl,.. ';""""'"•■ '■'"■'' M'it/.-t-x with tl,.. I,.,tt..>. ,.f tl,.. „,.xt" „.ix,.r in s...-i,.s that all tl,.. sp,tZ-l.„X(.S ...M.hl h, k..pt „„ ..„.. t\nnv. tl„.s i„,p,„vi.,.' the sui,..rv,si,„, .,f th.. w.„-k. Am ..xp..ri,„,.„tal ,,la„t „f this „at„n. was ,.n...t..,l at th,- nul .,f ,„„• X,, 2 ,i,„. ,^,,,i„„ j,, s,.pt..,„l„.r ]|I10 a.,.l i.rov,,,.: hi^^hly s,m...s.sf„l. tl,.. syst,.,,, uas alt..,-,..| with ...w,!!,!,.,,...; tn this ,„..tl,o.l ,.f wofkins.'. Kxp..i.i..,i,-.. shows that. Un- i,l..al work th.' 1....1 material shonl.l all pass thr-ou-h 40-„„.sl,. hiit it is i,„possil,h: to s,.,.m... tl„s ..o,„li,ltion .,r griii.lint,' at all ti„„.s i„ th,. ,„ill as a..s,^M,..,i. .Mon.ov,.r. altho,.trl, th,. Sitlphi,!,. < '..rpor.atioM was .p.ite awar.. that i,„prov(.,„..„is i„ ..l.aracter of plant a.,,1 „„.tlH„|s of "Peratioi, -.......-ally w,.r.. ea.sily possil.l... th.ir att,.„tio„. hv (,„,.,■ "t M,v,i,r,,sta„,....s. ha.l to 1... t,ir,„.,l s,.,lulonsIv to i,„.r,.asiM,r the P'-<"l<'<'t>oi> with tl,.. applian..,.s at han.i. As illu.st,-atii,ir wl^rt the "r,t,.r n„.a,is l,y i,l,.al ^'r'i.i.li.if:. the records of the avvra -,. ass-.ys of r,.s,,]„..s show ,-onti.„.ally that wh.-re the av,.raK.' in y.im- is from - to _..)',. that portion rftiiaiiiin^' „„ 4il-ii„..sh will a.s,sav from ;( t., 4^- y-inr. As ill.istrali.if: th.. diara-.ter of f..,.,l. an.l provinfj that the pro..es,s IS t.ai)al,le of l,a„,llii,jf sueeessfnlly the verv finest mat..rial slzlns.analy.s^^s l,y eommen-ial screens of th.. f.,..] to the j'ine-s..,.tioi, /ine-,.oneentrat.. as shipp.^,!. an.l .le-I..a,iin- ,,lant l..a.l-..on,.,.„trat..' as shipped, arc given : Feed to zinc section. 1 z inc ■oncentrat c. ne-leadin^ lead Throimh On 'r Throiiiili On -; Tlirough On '"r 40 4U 60 11.2 21.4 40 40 III) 1.5 40 40 60 1.9 7 5 60 80 19.4 •0 SO 21.1 CO 80 15 8 80 130 130 180 15.6 7.3 SO 131^ 130 ISO 21.7 7.4 SO 130 130 ISO 18.8 S 5 180 — 25.0 ISO 31.4 ISO 47.5 RKsn.Ts OiiT.MNEi.. For .•oi„paris..n with the work of the old mill.^the^following summary of results achieved hy the existing plant v.-ill lu- (if intrrcst. li.is iaj,le summarizes work don." on a commercial scale in th.. Central mill over a period of twelve months, ending H.nl NTluN M |IIK (I.NTKAl. MINK, HUoKlN llll.l, ] iV, "-■'■'•inlM.rL'.s. I'M-. ,u„l ,i<.u i„ l,a,i,l (uv the i.nprovetne.tt "t the trriti.lin- hut it is felt that, as the proporti,,,, „f l„wer-level or., merea.ses. the fr.-i.„lin^ appliat.ee.s will have to he i.i.Teased in or.ler t,. allow for the ti„er erystallizatio,. „f the u.n.erals in the ore «.s t.irther depth i.s attained. The writer i.s of opinion that the fipnres riuoted clearly .show that if the i.leal f,M-indinfr i.s ohtained the already high recoveries of metals will be further aii ''--tliu.j?. WlH.n ..n..l„.,i ,„.., ,.,vv,„u.sly „ux,..i uuh wat-r a,.,! a ivlat.vvly nunute ad,l.li,m „f „il, is aj,'itat..l violently i.. tl,. I.ns.„.c. of a,r, a froth is for,„,.,l. Tl,is frotl., risint? f. th.- surfa,-. '" '"• l"l'";l '"..MU.V, ,s la.k.,. with sulphides or otiu.r nivtallu- |nirt.,.K.. uh.l. th,. ..arthy .aat.riai, or «a„j„u., suhs,.!,. to th. '""torn. Jh,. troth is ••thi.k. ,.„h..n.nt, a,„l ,,..rsist.„t "• ""■ '"nnaliou nf this froth ,lrp.M,]s uj.om a .uin.h.r of phvsiral .•aws..s. of whi.i, 1,,. huo.an.y of o,l ,s the o,,. „.ost Kc-.u-rully a«.so...at...l u.th tin. tlotation process. Surfu.... tension, however is the phenomenon to lu^ .■ons„hre,l lirst. Then vis-^osity Kvery M.illnian i,as had oeeasion to notire how "sulphides are '•arne.l on the snrfaee of wasi • ,er in a stan,p-null; for ..xanmle wl.^M water IS pa.vse.i over the .,., surfaee of an an.algan.atin-tahle or a vanner.helt. The n.etaili,. partieles are dry and to their snrfaees IS* attaehed a tihu of air that Inioys tiiem on the water. To a .similar oause ,s due the lo.s,s of "Hoat jrold' in tailin- Most of us learned '■arly thiit greaM,. of any kind was had for amal^caMiation. It 'siekens' *('■■ 'i;. suvcr, e,..ntit.- the -loholes ,«o that they do not, eoalesce hut ivinam m a 'floured' or nunutely ^dohular condition Th„ ;ui. a.-ount for the loss of ,,uieksilver. hut the further loss „f ^^old nn.Jt '"• '";i"'""l '" ""• ''""t "'at the tine sealy hri^^ht .old attaehes it.self '•f."ldy to ti,e oded .spiieres of niereury and is carried with them into tile creek. The surface of any ]i,,uid behaves as if it had a film or elastic skin. 'IN, tins fact is due the variation in the maximum size of . rops oi .hflferent li.|ui.I.s. As the drop cnlar^^-s. the stren^-th of this sk.n is exceeded: then the drop h.vaks and the li,,ui,l falls When an iron rinp is dipped into a solution of .soap, it will 1„. seen on taking it out, that a film of the liquid .stn-tches across the rin"' II a .small loop of cotton, ,,ieviously moistened with the .solution IS placed on the (il,„ left „„ ii,e rin- fins loop can he made to' a.ssuine. a nd retain, any form, such as is shown at .1 in Fi- 24. If, «That is the de.s,.ri„tio., ^-iven l,y ,ho Minerals Separation motalIu.-cis.« n,^,Vine ' "" '" "'""'''■ '""'"'' '"''■'"■ "'a '•'>■ "''»^^ "«i"B '!>»■ Callow U II \T l> H.uj- \|-|n.\ lL'7 li"u,.\,.r. ill., tilni witliin 111.. Ic.p is l,n>kcii. 111.. Io„|, iiiurH.,liat.l y ;isMiii,,s t|„. .iiviihir loriii. shown at /; ; .111. 1 iT ii is now ,|..f,,n.-("l in Miiy way. on hcini; ivlrascd il spr'iii'.'s hack at oner f. a ciivl... Fio. 24. Th.'.sc plicnoMi.iKi indirale tlial the parti.'l.'s at tli.. surfa.v ..!' a lii|uia liavf a jiivat.T r<.li,n-ncc than the partiidis in Ww interior nf th.; li.inid. The foruf that, .ioes tliis is surl'; tmsion. The oxperiment with the rinj,' and the h>op. for example, is ex{>lained liy the fact that, in the first i)laee. "th.. surfa.-e tension of the liquid aets ecpially on both sich'S of the eotton, luit wien the film inside the loop is hroken, the snrfaee ten.sion only a.'ts on one .side, and hence draws the loop out into a eirele,"v Surfarc t..nsion ean he measured. A framework' (Pig. 25) eoiisist- A C V-r. 1- V ^ini-..>uitl ut I-II.M. tA Text-nook of Pli.vsics.' ti.v W, Wat.^^oii. iiage 19]. ■■A Tt'Xt Book of ttie Friiiciiiles of !'livsie<.' by Alfred nanniell. 19]]. I THE I-I.OTATIUX l'li(;(;KSS in^,.fa,r.ns^,.,.s.. l,„-.l /;. .,,,,1 tu„ ^n,„v,.,| slips /'/> an,l I' F / / >: I.nsh,.,| ,.,.„„., ., y, „„, a ,„,„„„,. of ,|„. l,,„„i ,s r ; ; 7'*''' ''7', ,'''"■ ""''•'-■-^•-'-'•■•i-,hsa,„l„nni u ///s ,.„„,.,, n.,,..iy;. Ti„. nunnnmu ion. ,.,.,, uin.,Mo i'- .s »,,..,. w..,.l„ o, ,. ,,„„, Tins w,.i.l„ SUSP..,,.!,.,! on tlu. "1 '-■•I unls tl„. tens.on of th. lil,., n„ ,1,,. nuv. If the fihn stn.tHu.s ;'•'•'' 'I'': ;-■•■/// -s . I /^ .iH.n , In. lilnM.s an area r /;rr-" """' "■'■'"'" '"■" i'* 'iistnlM,t,.,| ov,.r th,. Invadth r /; ■ ul„.n,v iC r ■■•rn.s.nts tl„. suprrliriai tension arross tli.. unit of l.ngth r A'. tiirn 1,11/ =--- r.r' E w 7'-- - ";■', Tlu.s the fon-e of snrfao. tension l.etneen u.ter an,| a,r l,a. i.een detennme,! : U ,s ^ .,,..„. per linear .neh or M dynes* per eentin.efe ui.Hl, iK.in,^ ,nte,.pn.,e,l n.eans that 40 ,M.nns uouhl he supported hy a dim one foot lonir. ' The surfaee tension of various liipihis is as foli.iws: Tensinii or t^ni ia< «■ s ■()■ ,i ,i,, .■ •'tin il,..liq„i,l from Water '", ''' '"'■■ ^V.,,.,. l.(»0 a] J J. 54 S40 A-io '^'^"'■-i „.:;. ^ *^^ Olivi. oil 7 • • ■ ■ Tu,„.nti„.. ■;' :l''! -"^•= U.^S -JQ - 11-- IVtrol..ui,i I, -f, :^-^ ^l-^" Thes,. ,u-e jriven .n dynes p,.- eentnnetre as detennine.l l,y (^nin.ke, ami n--..-.led H, the ':..,.,/./.„/., ii,.,7.,uur.. Ifowever. a lupiid lias another eharaeterist,, that nu.st no, he oveHooked, nan.elv v.seos,ty or resis.anee ,o How. This ^>ves tonjrhness to the super.ie.al lilm \\a,er-sjn, ers will rnn over the snrfaee of a pool like hovs .. skates over thu, lee. The spider's feet do not break throufrh "'"""'f'' '■"'■'' ^'•^•"'' >""k<'S a dinipl , ,he surfaee. H. U Dii.,; ^"■'"''Il.v nuasore.! ,he pressure ex.rted hy ,l,e spider's feet on the "ater_ He photographed the shadow of the din,pi,. and the,, niounted o.H> ot the sjHder s feet on a deliea.e halanee and mad,. ,t press on t '<■ "^.tt n.ade a dnnpl,. of ,he san.e d,.p,h as tha, pn.vonsly oiiserved. •' ''''"• "" ^^ '»''"'^'' "'' ""• ^i"'.i''''t is ilhistral.-.l i,y ,he fan.iliar *Sep also patzp 11 of tlii^ i,««v \\ 11 \T IS 1-I,()T\T|().\ .' fxpci'iiru'iit with ;i yn'ii.MMi iir,.,ll,.. If 12:» villi i)lacf iiii iiiviiiiai'v rifriilo say, a lar,. nirdle suitable lor use witl. No. .so ,hn,„|. ,„, ,|,;. ,„,,,•.,,,, '" '^ i-^vl of water, it sir.ks at .,„ee to the l.ottou,. m obedie.M-e ,o 1"; 'au ot gravity.;- If. however, you pass the needle through vour liair,- so that it heeonies givase.l, it uiU float on thr wat.-r \Vliv the ditierenee of behavior.' In its ordinary state the ne,..lle has "a ';'"'"' ■■;'■■ atta,h,.d to i,. That liin., l.ing loosely held, is ivadilv -lisi.la.ed by the wat. r. so that the nerdle becomes we.ted that is Hs weight eauses it to break through the elastie skin ,-o,i.stit,itin.^ the suria.-,. of f|,„ wat.r. ()„ ,ho oth.r hand, when th. u.edle is f?i-ase, I th- fihu of air aronn.l ,t is disj-lared by a film of oil whieh IS hrmly hehl. because lustrous n.e.alli. surfaees havo a scLvtive adhesion for oil. .^I.uvov.r, gas-s have a marked adliesivne.s. for ">l^. so that air adheivs readily to the film of oil „„ the nee.lle On ai-ount ot this enveh.pe of oil and air, the nee.lle is not w.ited that IS. It tails to ruptt.re the surfaee. The needle li.s m a .iepres.sio„ H. the surtaee of the water, but tlie amount of displaeement does '""/"•'•'■'■•il for th.. rtoati.ig. Viseosity, however, mav plav a part b.v inerea.snig the tenacity of the f.Uu. the particles of whii-h are so held together, or cohere, that the needle fails to part them. In short although It IS eight times heavier than water, the .steel floats Another suggestive experiment is that of the grapes in soda-water 1-d a gla.ss two-thirds full with soda-water from an ordinarv 'svphon' ;"nl then .Irop two or three small grapes into it. The g'rapes sink '■; ""■ l"'tt<,m. but they b,.eomc restless almost immediately and soon nse to the surface, one after the other. Thev ,io not remain there- hrsi one and then the other sinks. This performance will continue '">• I'alt an Hour, the individual grapes rising and falling, not alwavs Hi" whole wa.v. but maintaining a condition of intermittent activ.i" I liey become quiet th of the graiies sink In the end the bubbles b,.come f„„ !•!,!" ''!!"^_'I'." "'■"'*:""■ .^" "''" ""' ''"''••• <■'■«■ "my part of tie. way: Dui'iiiLr the earlv it too tiiiallv. iliey lie iiiotionl(.ss at th.. bottom iS..,- „;^,, |,|,. .1.-7 aim :;.,i; „\ iliis liooli. -Or even tliroiiKli .vnnr fiMi;ers. 1.30 TlIK ri.oTATKlX i'Kdfi:: •■"•I'vr jK.rt nl ,h,. ,„.,.fon,„nr,, ,1,,. t:r.|„. will . ,ik,. ti,.. snrfa-,. „f 'II.' "airr ami vrU,uwl ,■,,„„ ,, as if it uviv a innnhraiir I'- I'uovan.-y of nil is ,|„. ],|,vsi,.al Tart most assonat.,] wuh I'" lirst ,l,.v,.|opMu.nt of Ho.ation. alth, u^^li il is .sul,onlinat.d in th. '''It.T I'hnsrs of ,|„. pnHvss. .),] has a sp..,,,!,. .nuity j.ss ,l,a„ thai ;'l "al,.r. an,l tia.n.for,. ris.s to ,1,. surfa.-r ^^hvn niixni with uat.,- iH' li-ht.T oils ranj:,. i„ sp.riti,. .,,uify from ().,s to ().!.-,. as a.'ainst ' '•■ 1" "I wat.r, so that th. .nartrin for l.uoyinfr parti-l.s h.'^avi.'r tlia.i wat.T ,s s.nall. For .nsta.Mv. to ,„ake a ,uixt,„v of y. M,lphi,l.> '"Hi '"1 ns l,.-ht as water, it u-o„l,l l„. „,...,.ssary, .v.,, with th. li-ht.r m s. to us. iron, ;! to l,", titnes as ,nuH, ml l,y wrij^Iit as thr l,h.,.,|. ilns s„,.,..sts that flotalim., ev.n as .•on.lurt,.,! on tl,,. li,„.s of the "I'li'i- pat.'iiti'd processes, eaiinot be of oil. due eiitiP'ly to th,. Imoyaney IIh' sele.tiv,. a,lhesio„ of oil for ,,artie|,.s havi,,- a metallie ustre ,. a ,le,.,sue faetor in the proeess. It has hee„ said that liis adhesiveness is eliaraet-rist ie of sulphides; hilt it is exhibited 'v tellnndes and hy ^rraphite also. Sinularly. it has hrm impnl..] ''\ '"""■••■•'' "'"i to • metallie-^ partieles. h„t both terms „,mld imdude substanecs o,i,s„l,. ,h,. ran,.- of this ,,heno,nenon. Apparentlv if is 'I- '-''a I-- lustre tiiat is the decisive factor, for this 'would ""•'";''■ '!';■ ""nerals especially anumable. such as molvhdenite frraph, e. the telh.rides. and the bri.dit sulphides. The etVc'-t of this •nnrked_pret..rence of oil for lustrous metallic surfaces is intensified I'y tlie tact that cases ^sud, as air'^ have a sindlar adhesiveness for "II. so that, li present in water, ihcy will .join in prcventin.- the -•..n,^o, the metallic surfaces. It is an e,,ually important" fact tlial Muart/ ami other Raiifruo-minerals. havini: ., 'non-mctalli,.' .s asrainst a -tm.tallic' Ins.re. exhibit ll„. opposite prefcvnc : thev ,re feebly .adhesive to films of oil. and therefore to tho.ro,lu,...s anotl,,-,- ertVrt nai„..lv "f' "''^•'"' H,odo,.l,n,site. or other ..arbonat.s su.h as are prcsM.u, ,t ,,s po.s,l,lo to n.h-a.so the air in the form of I,uhl,|,.s that attach the,nselve.s to the „>etallie partieh-s. Uke th. hla,i,h.rs use., hv persons U.„„n, to swin.. Mo, ver. hy a violent a.,tat.on of t , nta, ^le a har^e volun.e of air, which will rise (hn.n.h th. ,„a.s ■" tlH^ -rm ot niyna.l hnbhles. crmstitutinjr a foan, or froti, ..f varyinsj stron<.';ii an.! persistence. "il rcluees the surface tension of water, that is. hetv .vn water . H -n I „re water has ,reat surface .ensinn. it also has no super- 1^1:T'\''''^''' '''''''''- '■'•""'■ The addhion ot' oil lo^^ers the surtaee tension and in.parts a decide,! viseositv to the M,rf^.ce of the water. That is why th. pourin. of oil on troul d ^Mte.s_ abates ,i,e,r turbulence. That al.so explains whv the placin.^ 0,1 u, stagnant pools kills the larv. of the ,„osquito, which the,'; hnds ,t ,u^,.,sMhle to a.ihen. to the surface i,y their l.vathin.-tuhes (S(.,. i< ]ur, 26.) Fii: ' M» AK ,„. lllK M„s,;llTO .VTr.^ClIKM TO SIUIV. K 01 WMI It. r.i-2 TUK FLOTATION- I'liOCt-SS . *'"" ;■ ' ■■ l-''Nt,r,.| ,snM,,-l,ul,l,l,, Tl„. oil nf tl„. s„.n is -u, ::;';;"■■''.; "'^'.' ;'77 "-"•■•■' —,.„,,„•„„...„..,. „vs,,,,.„: '" -Pnn.y, ,„akn., „„. m.n stro,,,.- and I.ss p.-one to ..ollap.so < 'Ins,. -n,l..rs,l,,. ,,u,,i,|,, ,,,,,,,,,,,,,, i,,,,,,, Th,. huhhl.. .In^vfo e is ;■■<;''-- lHs.n.u,n .,■ sn,.ra,.. ,.,s,on, .n.. , Ms an ..h.,i,. si ; ^-''■■- <;"H'-n. .as. l,k,. a i.aiioon. H,.,v also .he p.-op.Hv of vis.osif ; .; pnsunMo ,h,. au^ as in a.hanon. .n-,.s t™nM,Mh. su^ '•"■ . .""■ ';-•""■•"-„ of low tension an,l l.i.h vis<...si.v ...ahh-s '■'''!'. ns.n. , n>u,h ,he li,„i.,. to envelop itself i„ ,„o surfaoe fihn "' ""■ "l.n.l wl„-.h th.. tension of ,he l.„bble-,ihn is not stn... enough ,o „.eak^ ., nurt the l,„.,Me endures. Tl,e nois.. n.ade , ^ ''""'"-, " r ""'•'''• «"^'^'-'^ t'-^ fa-t tlKit it is a reeep.a.de of ene'.-.v * I . J|uhl,le .s spl..n,.aM,eeanse ,ln. spin.n. is tlH. slu.pe involnn. 1 es snrlaee o,- snp..,.,ieial area. Ti. I,n,,l,l.. has an a.tinhv ' '1- Ins.nH.s „„,all,e partieh. and adheres to ihem. as it also .dh,.n.s o hes-noo.hsidesofa.lass. This par, vie of air. „r ,„her ' ^^1" I' t has been .vnerated and the n.e.allie partieles do no, 1, eak- n.nd, .hjd sl<,n f,,r ,,,,■ san.e reason as ,he greased need),, fade, '"' ill-owned in tli(> water. ,„/'"'"■ "';."""" "[ "'"'''" "''^ "■^■^'^'■^ ""■ '■"•••""'i'^" ^'f t'uhhles in I nass otore and wa„.r. Ti,ese three eonstitn,.nts of the Hotation -'( ^.-e nuxed udnnately so as to f.nn an Vnnd.sion.- .sneh as ,s P .H.i In- .Mayonnaise. The air present while ,he ,.n„d.sion is l,ein. ■I'i" H.rn.shes the pras tor the hubhies. In order that thev n.av lif^ ""■ ';";'^''I"' P'-t.eles. they must endure lontr enough to permit -n|Pl''t-.'|..ra.,on ,,f the .netalUe part.-les fron. the earthy partieles . t .s. the sort.njr ot the valuable fron, the non-valuable ..on.pon.nts •' •«♦ '""^t be slower than that at whi,-l, thev a- I.-.nfr lonned. An etl'eetive froth repivsent.s a n,ultiplieitv of I><'.-s.s,ent bubbles. The .vlative .stability of the bul.bles depends'also "'7; ""■ '^""' "I" '"1 'Mnploye.l, P.ne-oil n,akes a brittle nhn : ereosote yields an elastic enveloi)e. I'..v a wonderful correlation of physi.-a! forces, the metallic p,,.. nH,^co,„e attached to the bubble. n,a.le in the u.etallurgical cu.ul- mx(u,.e IS atr,tate,l viol,.„tly i„ th. p,.,.s,.„..e ,.f ,-;ir, ,,v p;,d.lh..s '"■ lH.i.te,-s. I.y ,,as.satr.. tiirous..), a .•.■nt,-ifujral pu,np. or hv jets of eoiupressed air. A.i,! is „ot „..,.,.s.s.„y. as w,. „ow k„ow,-\"al'thou.^h It has h,.retof,.r,. 1,...,, ..ousi,!.,,.,! .....piisit,.. \V;„th,.r oil is al.s,.lute]v ess..Mtial ,s ep,.„ to ,1, aht. A.st ol all IS to attach 'life-pivservcrs' or .soi.iething buoyant to the mineral particles. Herodotus .h'scribes how ■'the virgins drew up gohl bv n., aiis of feathers daubed in pitch." Therefore this or an oil, for in.stance can be employe.l to float mineral. The Elmore patents for this flotation, due to the buoyant property of oil, are still in effect. Owing to the large quantity of oil necessary, as well as other things that make this method of no commercial value at present, th- only 'why' to be considered in this class of flotation is the si'lective action, which will be (liscu.s.scil later. The simplest a.,,1 ch<■ap,^st 'life-preserver' is undoubted] v the pneumatic one, which is beyond the time of Herodotus or perhaps even history it.self, since eggs and .ream were surel\- f.-,.tl.ed before the stylus was khuwr,. Aii.v liirie gi,-I who has helped her mother ni the kitchen can tell how any foreign substance, sueh as a jiiece of egg-.shell for instance, is buoyed up and brought to fl.e surface bv 136 til IHK KI.dTATKl.V |'i{,i(i:ss ''"■'"' imim,i,.s, 'n,,.s,. .,,.,. I ,,i 1 1 •-•-!.>■ u.nnua, n.; ''7'' ;'''■■'''■'' "''^'' '■'-'''• ■-,..•.• is --plv ;,,,,.,, ,r ,,i, , '^ '''''•:'^" '"'-'■"'•'"■" ■'"-"I". IHM , his u.s,,.. ■ '-'"'^ '' •'.v-pr.uiu,.. tl.„ u-„ul,I ,„|„.ru,s,. ,., ,„ .■-'•":■*■'■:-.;" >■ .'■'•^ .•iou,i „r s,..., V ,.„„ ''■'"""■ ""^^- -"•••"">',i..,i i,v ,, nr. nr attacliinjr .-, if liiiiihlcs t,, niiii.Tal - ■M.Hw 1 ;';;.:'. :''''7''' ''-- •''.'.>'''■■ ... n.. '.^.'inn, ulMl,. in, !,..,.■ ;.'.''''•'''■':■ '^''-' '■-"--. n- w:lll,.. ,,,!<,.„ up la,,.,- '.VI- <" ...-Inn,, is „s,.,l. TIh-s.. TI.Mvlnn^,!,,. ,w,, prim.. ,...., ,nsit,.s,,,rt,,,,,i.,,,,,.. '■ -\tta,.innent „l l,ul.l,l,..s to solids- ...Mt;,;;::;:;:;;:;:; •:;;::;-• '■''-''--■•^^ ---'- -i^.r:;;"..:;;,;-^:- :';::;■ :';:;' ■ '^- -" ""• -• ''um!;;::';i;: '::::r;:: ;;, '";■ "-^--■^ -• t... iish..s ,„a„e '•'- v,.a,-s a.„ kn w u m " " ""■ "' '"" """■'• "'"' ^-^ -- a ■'•'-■•■ was ,,i.!..I J' ■■''"'■'• '■"'!'-'''''-'^-'-''-'''''I- in uat..,.. ' n Mown in,., ,h,. „-„,.',. '"' '" """ "I.''''' '.<'v.> '■'■'. 'i-^i.. V'-i L- n i •'; "■ "".'"'■^^■'''" "•■•'.V -stain ,1,.. li.V ... this uav. ,."..:,/"" '^ ■';■'■ '""■•"""''"' '"^^ '^ '--"i.! '•.•-y..'n'r,,,.,.;;;,^ V;;.t^^^^^^^ Ava„a.,l,. air "hrn proM ,s .lissolv,.,;. ()nly nas..,.„, LJ^ ,:.;,, "l,;",;,' ";'';''■ • ^as ,,iM hf. a„a,.lie(l ,,, mineral WIIV Is fi.otatiun ',' i:i; t H„„, ,„„^^,^ '''-'a,., is,,ui,.kly.i..,„ons,ra„.,ll,vu„n,. r; r •"■' "' -•. ""•> ""■ '"'t'-n of a ria.sk. ,ill..,l „.„li u...,..,. . riou o tiM.n- own a,.,-.,nl. .vfuso „. atta,!, ,l,;.,ns..lv,.s or 1„. ;'";"'•'' '" ."'" ■^'""" '""'•''<- '"■ ••".•.' To pn.v,. that ,1,.... sanu. -•'''I'- P-;t-l:'. . an 1,,. H.a,,.W l,v ,H,1,|,,,.. ,,r air. i, ,s onlv nX"^^^^^ •'• '-;:- ,I,e M and pla,.e ,1. riask on a hnt pla... w,u.n --■'I-., y .-olh.t an. ,lr,v..n on, of solnt.on L ,„.. ,..,,, ,„;, '' I -IH. sur ace. Son., on,. „,ay lu.. renuu.kMlna ,1,,. ns.. o,' t..nu.^^^^ • - ;>^ ^IH' solnnon ,.ansc..s ..nonKl, expan.sion o( ,1„. air hn ,1 s • on.. .anu,nn..Uh ,,. ,a.or„,.„.,. .niknltlns^^ — on no„n,^ ,1.,. .nvally u„T..as,.,l si... of ,!,.. I,nl,l,|,.s Whv '!'■''•'-''•"'-■ '-'.1.1.S I. a.taelnMl ,o „,in,.rai p.Mlu.l,.s in tl.. 1 ; ot na.sc.nt (.r ili.ss<,lv..,| air.' ' All ,M...a, fac.,.s. wh.n thoron^Wily nn.lrrstood, an- .icnionstrahl.. y snnple oxp..n„u.n,s ui.h n.a,..nal a, hand. .Sonu-tinn-s wh,., own. n,an a. t ■. soda fonntain al.sent-nun.i.-dly fo.-.Hs ,o s.i,- ■ ..^ P osphat. an,l s,.,s h.-fore you tl.e straws. r ,„to th. eolorod syrup in the hot.on, of the ^lass so as to form a few sn.all ],n.,hh.s that eau he wat,.,.. ; .-ly. These hnhhh.s that eon.e to the .snrfaee are eolored. Vi ■-.-;• 't-» -•"" "^'"'■"'- '^■'"^'•••'■•"•"- ^'"- *'- o"Iv part of he l.-l"-;l that ,s eolored. i.s in ,he ,,otto„, of the <,h..s.s, th; L „u t e onveh.ped .„ the same identical portion of li.p.id thr H i pass...e from the hotton, to the ,op of the .hJ,- I„ otl.: w rd the an- „.bh,e on being introduced into ti,,. ,,„,!,,. , uZ^^'w urrounded and u.elosed by a fih„ of H.uid, Ihich ren.ai that a.r bubble tiiroughont its pa.s.saee just as if it were •. Zrl I t M..bble. Here is a concrete e.an.ph^ of surjlc^ tlml. " r^ that an be measured, as explained in any text-book of phvsies Tins pheuonienon is worthy of investigation. The bubble ri,s<. to tlu. surface of the bquid by rea.sou of the force of a.avitv Tin js the force of gravity is greater than adhesion of the n^oLmles o the air tor the mnWnlno of ihr- ];.--;.! .! ._ ■ mnahijn the liquid. The molecul^^'of ihrnl^id "mr Ji;^y •See also p.i-es .^IC and ,r-,7 of this hook. l:{s TIIK FLOTVTIIIN I'KOCKSS iiHK.Ilf: tll..|„.srlv,.s ilc.-nnllMj,' to tli,. ,|,.(ililtiu,i .,f a :.,||,i,j. |„ ,,,|„.,. M.>r.]s, the fonv «( volwaum of any sin^'l,. niolwiile witlmi Ihr li,|iii,i IS .MilDilix,.,! |,y ,|„. ,.oli,..siv.. fom. ,.f otlicr .ll()l..culr,s of th.. liquid. An .■xtran.'ous fono woul.l !,.■ miuircl to s,'i)arat.' tlinn. An air I'lil.lilc, for install.... iiitro,|u,-,.,i info ih,. |i,,i,i,|. unhalai,r,..s this '■-li-siv fn,.,.,.. It is s.-lf...vi,l,.nt that this foiv,. of a nmh.nih. must .•ft .■.|iiallv III all directions from that mohriil,.. Th.T.for.. iii..h. that there tli..ii .•M.as a -|.,.aler ,.,.h,.siv,. for.-.. h,.tu>..n tli,. m.,h...uh.s imm,..liat..l v surn,un.lin..r th.. air huhhh. than that ...xistiii- iM.tween th,. m,.i....ul,.'s in til.. intcri.)r of th.. Ii,|ui,i. This for,.,, is 'surface tensiim;' it is S.I frr..at that th...s.. m,.h.,.ul..s .if th.. ji.iui,! surrouii.lin<: the airhiihlj.. aiv lirnily h..i,l t,.tr,.tii,.r an. I t.^rn hu.se from a.i,ia..eiit moleeul,>s .,f the li.iui.l as th.. buhhle rises to tiie surfi Tliat is to say siirfat'e I,.nsi.in .-aiis.s th,. moh..-ul,s .,f the li,|ui.l to f.irm a film ar..un,l tlie huhhl,. aii,l remain with it t,i the exelusion of like m,.l._...ul..s during til., tim.. the huhhi.' remains in the li.iui.l. T.) all int..|its an.l j.iir- P..-..S. this film is s..,.n t,. h.. th.. same as if it w,.re a memhran.. ,.f som.. .s,.Ji,i. Til,, air in tii,.s,. buhbl,.s ean no m.ire e.mie in ....ntaet "ith the li.iui.l tiirouf.'h which it is pas.sinp than it ,.,)ul,l were it inside a t.,y liall.i.m. for instance. The buhlile may be sai.l t.) be .•n..|.,.s..d in a 'li.iui.l skin." Th..r..f,)re t.) atta..h this bubble t.i anv .sulistaii..e, this li(|iiid .skin must first be peiu.trate.l .,r bnikeii. As S(.(.ii fr,)iii above, tiiis r..quires some force. As shown abov,.. th.. force of chemical affinity is not siifti,.ient to over...mie this surfa...' t..nsioii. S.i then, it could hardly be expected that a m,.re adhesive force wouhl be fjreater than this surface tension. Th,.ivf,,r,., t,) atta..h f,'as 1.) soli. Is in a li(|ui.l, it is first ncces.sary to dissolve the gas in the liqui.l ami th..n e.\j)el it in a nascent stat(\ 'A striking oxperiPifnt to show tticse liciuid films is as follows- To a lieaker partl.v filled with a colorless oil, add a small (liiantity of permanRanate solution. Blow air throuRh a finely drawn-out glass tube into the perman- Kaiiate solution now on the bottom of the beaker. Air bubbl.>s enclosed in thf oolored li.mid film rise throuch the nil nn.) bre-?.k at the --.!;;-!■:•..•■:■ i-.:,. n:-.=c of the expansive force of the gas. Th.> colored water drops back through the oil e.xa.-tly in the same manner thai a balloon, bursting, drops to Ihe earth. WIIV is KI.OTATKl.N .' l.!!t Thfiv aiv at j.ivM.nt ..nly tlnv,. knoun uavs of foivi,,.. , „,s 'n-l.HMH.allv into .solution so ,|,a, i, aHually ."upi.s „,. .nh-rsnrial ■^''7if"* •'"■ '''I""' '" -"'-^ "' '"-tine ,. in .,,1, ..invrs or |...Mhs, ,.s ,. ,|,.>,.,.,l„.,l. ,or instan,..., ,„ tl„. patent papers of the Minerals Separation Co., u,„.re ,>n,p..ll..f.s or ,...ntnfu.^.l pnn.ps are —'1: 'J; .l.vniin,' it into sn,.|. nunute pornon.s tl.at. I,v eapillarv ""■■■•.. It IS aetnally taken into solution, as is .lone in a ('allou- eell- ;""' '■' '"tnulne.ntr it as a surfaee tihn .snrn.,n.,lin;j a jet of Hui.l by .neans of snrfa.v ...nsinn. as ,s done hy a .ne,ho,| nniler proeess haml; (I, Sup.r- saturat.oM, so that the e.vess ...s eo.nes ont of i,s own aee 'nl ; '^ heatinf, wh.eh e.xpels son,e of the ....s hy inereasin,. its volun.e- nml (. , re,inrt,on of pres.sure. The j.resent Kin,ore maehines work iH' pulp m a vaenum. takin,. advanla-v of the faet that "'at eon.stant •-'l-'-ature the ,...s dis.solved in a -nven volun.e of li,,ui,l varies direetjy as the pressure"— Henry 's law. Sinee it is ea.sh.r to work i^ the open air than in a vaeuu.n, flotation maehines nsins ll>f J.rineiple mention.,!, of forei,,.- more air into solution than tl,e li,|ui,l ean hold, are preferahle" The seeond method mentioned, of e.xpellin^^ dis.solved ^as hv heat ai.ls the super-saturation type of machine in two ways: (l)"„aseent cas IS expelled Iron, the li,|uid to he readily attaeh..d to solids for tlofi tioii; and (2i di.s.solved gas is e.xpelled from the solids .so that -ms hul^.Ies may he easily attached to them, llere^ lies the whole see;et ot flotation. Xo soliil ean i)e floated unless it contains some dis.solved r^as Whv ■> For the reason, e.xplained above, that the envelopi„tr 'liquid skin' .■annot he penetrated or hroken. It was shown above that a gas bubble ,s surnn.nded by a film of liquid. A solid in a li,,uid is in tlie same way, surrounded by a film of the liquid, for the same reason Therefore, in a liquid, the molecules composing the film around a gas buhhle would have uo more attraction for those composing the film surrounding the soli.l than they wouhl \v.no for anv molecules in the l„|uid itself. TTenee the bubl,lo would not altai.h itself to the solid. It is seen then that flotation has for a foundation a subject ot which practically nothing is known— occlusion of gases It is self-evident that the same cause which ten,l« fn .„..„. saturate a liquid with pas will also have fha same tendencv" to super-saturate a solid contained therein. And also the same cause 140 'I'lii; Fi.di- \riip.s I'Hixi:.-.-, Ili.il lrii,|.s I,, ,||s|„.| r,-,„M s,,hii„„i ||„. ,|iss,.l\r,l kmn uill also Innl t" .iisprl til,. .;ts lrn,u a s,,h,l „, ,|,,s sainr li,|m.|. TJi.Trlun. a s„li,| "1 " li'|iii,l h OH tllr silMa.-,. ,,(• ||„. sol|,l, Sulli.Mrllt .•,,i„|..„salinri will ,-,.ll,.,-t ,.„„||.r|, >ii-lr.ul,.s of til,, .as t„ lonii a hul,l,|,. „„ ll„. siirla.v „f tlic s,.ln| '■''"• ■'*"' ■''■"•'■ 'I"" '" .liirilsion ,,f i.Ms i,i th,. ,,,, posit.. ,lir,.r- """• "''^ '"' I"'"' 'I ''.V '■au.siiiir til., -a.s I.. I x",,..ll,.,l f|.,„„ '■'""''■ ""■ '"l""l '"• ■' >^"li'l '■ontain.',! m tliis li.|,n,l. Ati ,.xanipl,. "!■ tins IS tl,.' .Imnpins,' „r a r,,l,l ,„•,, jnt,, tli,' hot solution ,,f a t|,,tatioM '''"'"• '5"l'l'l''^ in iiMl.^ly ,n,| t„ f,,,-,,, „„ ,1,,, ,„.,, part ir|,.s. I,v iVMs,m ,,f ,-o|„.su,. a. Ml a.lhrsiv,. lon-.'s, and liav,. ||„. t..n,l,.n,.v t,. 1,',. cnlarL'iMl liy tli.. <,'as in solution in th,. lii|ui,l. It is natural, tlicn^for... to suppos,- that s,.li.|s with hitrl, „,.,.lusiv.. ix.w.u- r,,r i,'as,.s hav,. a jrr.-at.T t..n.l.'n,.y to tl,.al. II,. r,', th,.n i. a .■.•Ills,. .,f s..l,',.tiv,. rt,,tation. IF,v,,-kiah Uni.llor.rs patent No. :!4:,.|i.-,l IS th,. lirsf t.. r..,-,ijrni/.. this. S,„.akin- of m.^tallir partii'L^s. h,. stat.'s: ••Th.s.. floatiii- p,-M-tirl..s a| ar t.. p.,s.s..ss .soni.. p.-ruliar '|u.-iliti..s wlii,-li n.p..| water Inun th.-ir surta.v.s, ..sp,.,.iallv wl,,.,, su.'h p.-irtirh.s air .■.\p...s..,l. ..wn nioiii..ntafily. t.i attno.spii,.ri,. air'." Lat.u' liiis ph,.nonicn.ui .■aus..,l troul.l,. i,.. inst,.a.l of l„.|„.||tinsr. H,.hn.n who .says in his pat.-ut X.). 474..^i'f., an infeivst in whi,.|, is as.siirn,.,} I" CiiiTi,. .1. Kwrsiin: -l ...xp,.! fnuii su.'h niin.'ral an.l niptal par- tir|..s-tli.. air an.l otli.'r -a.s.'s— l,y pr..,iu.unjr us far as pra.'tiral a vHcunMi--or. aii.l i)r..f..rably. I.y applyinfj heat to th.' .)re. tln'rehv olitainin? tlie il.'sin-,! oxpulsi.m ..f air an.l ..th.>r iras.'s." Why th.'U ,io niin.Tals .h.u,. in tlu's.. pat.'nt pap.-rs tu.vinin.r soli.ls '•""tanun- uu-tan. an.l ..sp....ially sulphi,!,- minerals, .vrlu.l.. .ms,.s more r,.a.lily than ..th..r s.ili.ls? It is only n,..-..s,sarv t,. l.,..k int." th,. suh.i.M.t of ..r,. .l,.p,,siti.Mi tor th,. answ,.r. Primary sulphi,],. or,.s are ei.an ^^.il n.ar th.- surfa.-,- i,, snlphat..s. .•arh..nat..s. o.xi.I,.s. ,.t,., : ^■■As in flu ,.as,. „f li.i„ids. we would expert that the nmomit of •'■is ;ierature rose." .losiah P. Cooke. .Jr. Themieal Phv=i.= • -He uesentj.s a trav..li,ii,- hWt with one end in water to take ad\antaKe of this fael. This antedaf^s. and is the same principle as. the Macquisten tul...s \\ IIY I- H.olul,|,. ,„ ual.T Ul- uatrr Ul oil. Tli,.iv|-,„v ^^al,•l• uiU not adlu'iv I" a siirla,-.. wrtto.l willi oil or oil mil not adli.Tc t,i a surfar,. .vetted "illi wat.r. Al.so an oil. due to its i.roi>,.rty of ,.a|.illarv attraction lias that pow.T of ontrrinff solids. Therefore, owing to larger surfaces an.i pon.s. ia,,M „ulals and siilpliidrs arc eapat.le of ali.si.rhins; oil s.) that siitltieient oil can he attache,! for aL'u'loMi.ration and tlot.itinn. Tins selective Hotation. as nicnti, ,»,■,! ah,.v.., is not now worth eon.siderin^', h,- ,nise so larne a (|iiaiility of oil is necessary. -Mickle's experiments' show,,! that no,,.' of th.' niincrais tri,.,l hoi. ,.oI,|. or with rcluced i)res.sure floated on oil un,ler anv of the '"iiditions ^,U,■,■,■ ti,,alin- would fak.' plac on water. Tlii.s was to l)e expci-ted, since the specific gravity of oil is less. What th,.|i is th,. p,,t,.nt fa,.t,,r for s,.l,.,.|ive ri,)tation.' It is the 'il'ilit.v to vary tl„. --angle of hystcn'sis'." It has heen ,s.v„ from th.' ahovc that soli,ls oc,-lude gas which can he expelh'.i from tli.'m II this gius he expelled from them when tliev are in a licpiid at a time when gas is expelled from the li,|ui.l. thev Ixvoiik- the nuclei tor the tormalion of gas buhhics which will float them under .-ertain conditions. Now, Iheivfore, if it he possible in an ore i, xture to drive out a considerable portion <,f the gas from all the .articles then will be insiiffien-it remaining [n the 'gangii..' to fl,,at' it while- the iiiiiuial containing m,)re gas will float to the surface. It has been found, for instance, that sulphuric acid in very small ouantity ;id,lc,| t,, wat,.r will d.'crea.se the angle of hysteresis to that i),.in't where quartz and similai •gangue' will .sink, whih- that of the metallic particles remains practically unchanged. Since an acid in very minute quantity will i)ro,iuce this etTect, it is not due to rise in temperature or reduction in pressure, which would ,lrive out the occluded gas. This must be caused then by no ordinary phenomenon. The only way that an acid can act in" this manner 's in the capacity of an electrolyte, especially when dilnte.j ^Pi-oceediiiKs of the Royal Society of Victoria. Vol '3 Part ■> of K.ll •-•Trans. Inst. M. & M., 1912. Presidential Address by H. L. Snlirnn." 142 THE FLOTATION TROCESS U, Its dissociation jHiint. That, is. >:oini.l,.tc i.mi/atiou exists. Vcl witli this e.\trenie diliitioii, gas is e.xpcllod from a .solid contained therein. In other words, eciuilihrimn does not exist. Wliy? It is on aeeount of tiiese ions of tiie electrolyte which cause thisdisplace- ment of equilihrimu lictween the solution and tiie giw dissolved in the solids within this solution. This then resolves il;se)f into a siini)le ease of osmotic pressure. The surfaee of the solid is the septum. The ions of the electn)lyte enter the solid whil.- those of the gas leave. Since the carrying solution is saturated with gas already, bubbles form; and this action continues until the eutectie point is rcae' "d. .So far an acid (sulphuric on account of its cheapness) has been used as the electrolyte, because it produces such a great change in the angle of hysteresis. In the future, as more is learned concerning flotation, the tiner and more delicat.' manipulation will be better understood, permitting an alkaline electrolyte to be commonly us(>d. This will allow of the selective action for irniieral particles other than sulphides so that, for instance, cerussite or malachite .an be separated readily from gypsum, quart/, etc. This is not to be confused with Ilorwood's "differential" or "preferential" ])roeess, whereby the surfaces of some sulphiile minerals are oxidized by roasting to prevent them floating with another sulphide in a mixed stdphissure of the bubbles, so that they in reality exjilode. This is the case with bubbles in a glass of soda-water, for instance. IIow can this lie prevented? The small boy will i)rcvent it by coaling the bubbles with soap that is, by toughening llie liquid liliii. This then is the secret of "the froth-forming .iiateriar' so frequently mentioned in the varieus patent papers of the Minerals Separation comi>any. Why is an oil the most uset'ul substanci' with which to do tliis? It has been shown above that metallic particles are readily coated with oW. Theret*0!'e il ...1.. cohesive fon'c is exerted on the oil-coated mctalli.' particles. Bi^sides WHY IS KLOTAi'IUN '! 143 an fiivfl(ii)c to hold tlic i:n>. ...i atToiiaut uses a mt to strengthen his balloon, so that when tlic pressure is relieved by tlie higher atmos- phere it will not Imrst. This same etTect is obtained in froth-flotation, in the same way that particles form around drops of water on a dusty floor and prevent the globule from breaking, small particles form a network around tlie large bubbles. This is due not oidy to the force of cohesion of the oil on one particle for that on another, but the force of cohesion existing between the particles tliemselves. Thus a frotli is formed of bubbles that do not readily break. It is a well-known fact that water hiis the greatest surface tension of all liquids under ordviary conditions, except mercury. It is there- fore a safe assumption tiiat dilution with another liquid will decrease the su 'ace tension. The tendency to float is decreased. With re- duced surface tension bubl)les burst more readily. From this it is easily feen that surface tension is decreased exceedingly by the us<> of a volatile liquid. Alcoiiol evaporating from a substance held near a bubble will diffuse sufficiently to readily dilute the surface film and quickly burst it. Mineral particles floated when, for instance, amyg- daloidal or globidous eucalyptus oil is used will dance on the surface of the liquid, being apparently attracted and repelled until evapora- tion ha.= progressed sufticiently t.) equalize the surface tension not only of the lifpiid but of the l)ulil)les iis well. Water then is the natural and universal iredium for all flotation machines and air the necessary adjunct. The air may be in the pores of the iruneral particles and as films around them, so that they are not ea.sily wetted, in which ca.se the machine may take some such form as a Macquisten tube or Henry E. W^ood type — a purely surface- tcn.sion effect into wiiich enters notbintr but water and air. The meniscus of the water buoys up the metallic particles surrounded with an air film that preveids them being wetted. The force of gravity is le.'js than thrt of surface tension, so the particles float. If the i)articles be surrounded by a watiT-film. the cohesion of the molecules of this lilin for those of the body of water neutralizes the surface tension, and "lavity sinks the jiartii-lcs. Or again, minute bnblilcs may be attached to metallic particles that ne('( ssarily contain occluded gas. A thin film of oil may enclnse nr cont.nin the par'icles and Ihcir attadicd bsibbles. With sutTicient displacement the particles will rise to the surface and form what may be Icrmed a DeHavay flo!>t. Or, lastly, the tmbbles may bi' large and have the mineral particles attached to them, as veil as being attached f. each other. This is the so called froth flotation. 144 THE FLOTATION PROCESS WHAT IS FLOTATION?— II By T. A. RicKAKD (From the iliiiimj and ticifntiftc Press of October 2, 1915) All of the iiatuml pliuiioiiifiiii, or appearaiiL-cs, ilescTibcd at the begnuimg of tli,. previous artiele. play their part in flotation and each of them has serveil as the basis for one or other of the many patents that have involved the siihjeet in a maze of vindietive litigation. Surface tension is th.' idr;. underlying Ilezekiah Bradford's patent of 1886. Jn this process the dry powderrd ore is caused to meet the surface of a still Inuiy of water, so that the metallic particles, which are not wetted, are made to float away, while the gangue particles, which are wetted, sink. This was th<> first application of flotation without the aid of oil. In 1904 A. 1'. S. Jlacquisten invented a tul)e ai)paratus in which surface tension is utilized for concentration. In 1906 the process was applied on a working scale in the Adelaide plant at Golconda. Nevada, where chalcop>rite was separated from a lime-garnet gangue! In 1911 the Federal fining & Smelting Co. adopted the process for the Morning mill, at JIullan, Idalio, in tlie separation of blende and galena from a (piartz-siderile gangue. At Golconda 96 tubes treated 125 tons per day; at MuUan. 119 tubes fivat ir)0 tons. The iron tid)e"is 6 ft. long by 12 in. diameter. The interior is ciist with a helical groove. The tube is revolved at .iO r.p.m. Success appears to depend upon • he angle at which the melallh' particles are presented to the surface of the water. Subsequently, the water at Golconda was slightly acidified, so that it nuist have caust>d an ebullition of carbonic aeill gas from the lime in the ore. Thus the bubble phenomena may have come into i)liiy. Later, small additions of coal oil were made, so that another i)hase of flotation was inlro(luces floated on the water.* It is said that the sacks had become grea.sy, but it is quite likely that she used .soap, in which ,a.se the greasiness is not required as an explanation. In her proce.s.s the maximum addition of oil, namely, 18";,'.. is less than one-sixteeiitji of the quantity required for bulk flotation. As to air, that she olitaiiied 'X simKPstion that is confiiiiied by the statement of Walter MrDermott that "in praetirc [nf the p:iniore process] the afiitation with the pul|i results in the oil takins up a very apprerialile quantity of :iir. «ivin« a rertain sponginess, with natural inrrease in floating power." 'Thp Conroniratton of Ores hy Oil.' /■; .(■ .1/. ,/.. Fi'liniav. !4. lOOl!. paj-'e L'tl2. •This proves to have l.pen a .arn. See pape ,■{.-. of this book and Thf I'^verson Myth,' Vining and Scientific Press. .January 15, 1!)I6. 14C THE FLOTATION I'KOCESS I'.v liif .-iirilMlioii .>f til,- pulj. liy niriiMs nf two fans i-jidiatiiis from a liolhiw revolving' iiiImv Tlic msult a.vonlinu' ti, a drscription written 111 I.SIMI, not ill til., ii^'tit of piv.:ii(ii,v(l observation today— was the fornuilion of a ••thick sc-niii of siilpliidcs" that •'row to the surface and was sliiiiuncd ofV. Iravin;,' tin- liiiiicrto l)lack ore as wliiti- as snow." Fl(,. rilK. .lA.N.NKY H.Or.MION MACHINE. The original Inilk-oil prore.ss of Klmorc had iiuinerous applica- tions, some of which were fairly successful, hut in 1!.I04 it was displaced liy the Elmore vacuum process, in which flotation by hulk- oil WiLS suhorditiated to the huoyant etl'iM^t of air-huhhies generated from the oiled mixture while uiiiler a vacuum, and by heating. Under norninl cruiditinnc \V!it<»n I-.,. I, It. ;.. ^..J..*: i .r -: 1 . ■■'■■': -!" .i;:u;iii;i t;i a:r equal 10 2.2";, of its volume. Thi,- i.s liberated under a vacuum, but neither the amount of air released (especially at high altitudes) nor the WHAT IS FLOTATION? — II 147 (iiiiiiility uf (lil used surtiL-fS to cxplaiii the degree of flotation aehieved, as ineasiired in wei^lit of coiieeiitrate. Tlie pivsem-e or tlie addition of limestone or other carbonates, with the nsc of acid, su<;>;ests till- aid of bul)hh'S of g;is other than air. Tlie i>roportion of oil in this process has been decreased gradnall.v from 10 lb. pv ton. As the iiiixiiif; involves violent ;.i;itation. it secnis inevitalile tluit entrained air plnys a pnrt. To the 'oil and air* process \\l .uist add that of Edmnnd B. Kirby. f(jr which jiatent was applied in l)es " In the light of later events it is claimed that he must have made a 'froth,' because the oil was insunicient to cau.se bulk flotation and the agitation sutiticed to entrain enough air to produce a froth. To this the patentees of the so-called 'agitation- froth' process re|)ly that his "scum" was not a "froth" in tin ir sen.se of the term. That he produced froth seems highly probable; but t" say that '.scum' and 'froth' are the same thing, is. in my opinion, not correct.- BuBULKs. Meanwhile the bubble methods of f narles V. Potter and Ouillauie.e D. Delprat had been patente i in l!l()2. In these processes gas was chenncally generated witli a view to ])rom(iting the flotation of metallic particles in Broken Hill ore. This Australian ore contains calcitc. which by the addition of aeid, emits bubbles of gas that adhere to the sulphides. Potter used acid, agitation, and heat, while Delprat employed a hot solution of salt-cake or acid sodium .sulphate and sulphuric arid. Both pnieesses were successful on a large sciUe, particularly Delprat 's, which is still in use at the Broken Hill Proprietary mine. Neither used any oil. The bubbles Mtt;ich themselves to the sulphide (blende and galena) particles and carry them to the surfa. , . whence they flow with the liquor into a compartment where, the bubbles lin-aking, the metallic freight is dropped, and cullectcd as a mixed concentrate. T. J. Hoover says' tli.'it "the result of the manipulation to which the material is subjected ='Scum' is the impu.ity or extraneous matter tliat rises to ttie surface of a molten lead. 'Froth' Is a niultlplicit.v of bubhlcs, 'ToncentratinK Ores b.v Flotation.' Second Fdition. Paue 101. JrMJ Oil il UilLll Ul 148 THK FLOTATION I'KOCKSI IS tlu' lormatiuii ,.i n dense froth of Imhhles ami niimTal": lait this was puhlishr.i in 1 !»]!', a.ul must 1... read in tlie lifrlit of events 1,,,,^. suhseqiieiit to the eiaiiMs made hy either Totter or Delprat. In order to explain the making of froth without oil, he su^trests the presence in the ore of sue], suhstanees as •'yirld ^'ummv ortrani,- .■ompounds that selectively adliere to the ore." This is an imj.ortant su^'gestion He that as it may. the Potter and D.'lprat im^thods d.mmnstrate that flotalKm IS i)raeiirahl,. hy the aid of hnhi,]rs without the addition of oil. In tlie Fronient |.ni,.,.ss. patented in (ireat Britain and Itaiv in June lf302. the ])ul.hl,. id,,, i.s dominant, for. while Aleide Froment used od. he employed it to attraet the l)ul.hles of ^ras !.'enerated hy the reaeli.m between a.'id and cah'ite. aildin;; tlie latter if .suitahh- earhonates were laekinir in the ore. He emphasized thr f;i,.t tliat not (mly have tiie lustrous metallie partieles an atTinitv for films of oil. hut the oil itself attracts luihhies of jra.s. hoth air and earhon 'iioxide. He reeommends miK'h less oil than had hitherto been used Jiamely, a "thin layer of oil." whieli has been interprete.l, aee,,rdinfr to the exirreneies of litigation, to mean anything from less than 1'? up to 14^;, ae.ordiiifr as the Froment patent was bein ■lni\ :!I, im."., ii.-iRc i.-.r. W II AT IS FLOTATION .' — II 149 (lioxiil.- caiiyiii^' iiiiii.Tal." but if it carriiMl niiii.Tal I do not set; tliiit liis i-ffiisal to call it -rrotli' is of any frivat (•.)iis('(itieiiL'e to those of UN who are not iiitmst.il in the liti-^atioii. iiietallic particles of an ore, not to Hoat them. To an acidified pulp he added from 4 to tj'; "of the wei>;ht of metalliferous matter present," not of the ore as a whole: therefore, with a V2'/c zinc ore this would mean 0.48 to 0.72';. say 10 to lo lb. oil per ton of ore: ami with a '2';, copper ore. it would iiiejin only H to 2] lb. of oil. iJut this oil "is brought into the condition of an emulsion in water containing a small per- centage of soap or other emulsifying agent." Thes«' are the words of his most im])ortant i)atent. V. S. \o. 777.27:), dated December i;{, lI'iU. but in his tirst patent, British No. 2t),2!t.'), of November 28. l!io2, be gives the proportion of .soap as 2"";. When this mi.xture of ore. acidulated water, and soapy oil is agitated violently the metallic particles are agglnmerated into tloci-ulent ma.s.ses that sink, the sep- aration from the gangue being then ctTei'ted by an up-current of water. To facilitate the .sejiaration, the mixing was conducted in two stages, of which tlie second is said to have been "a rolling foi'm of agitation." Cattermole called his agglomerate a 'granule'; Froinent called it a "spherule.' FiiOTii. The Minerals Separation company was organ ixed in 100.3 to acquire the Cattermole invention and 1hereaft(>r his patents became part of the property of that company. The first and only plant to iisr the Cattermole process was erected on tlu' Central iinne at Broken Hill.'' where it was soon displaced by the so-called agitation froth process of Sulman, I'ii'ard, and Ballot. The.se gentlemen have testi- fied that they made their discovery b\ ev|)erimcnting with the Cat- termole process, api)lying .scientific methods of research, based on the fact that .sometimes 'Moose floccu,. nt mas,ses of partially granulatcil sulphides" would rise, instead of sinking. Finally, they decided that this was due to in.suflicient oil. The actual experiments were made by Arthur II. Iliggins. who, by diminishing the amount of oil to 0.()2% on the ore. cau.sed so many of the metallic particles to ri.se that a high recovery was obtained by flotation. IF. L. Sulman says that r.y rfuucirig Tiu- aimiiiol (li uii iiic ^ranuiaiion was stop[)e(i and "co- •■■'Flotation at Brofsen Hill.' By .lames Hebbani. Miinnfj ni.d Seirntifie Pr,-\s. Sfptembei- t. liM.'. See paup tin of tliis boolv. 150 TlIK FU)TATI()N I'HOCKss ".-hlrntally n niiii.Tal ln,il, lu-gan lo takr its phi.-e.-' Tl.is was in Marcli m-,. WluTcMip.,.! tlie Uritish patonl of .Minerals Sopaniti.w. N.. sity c.f a!.'ilaiii)/i iv(|iiircd to spread it tliniuu'lmut ih.. pul|).- Tt.,' vii,'()i s H. L, SOLMAN, H. H. GHRENWAY 4 A. H. HIGGINS, ORE COSflNrHATION. ArrLECATioa tin:} apk iS, ijoa 962,678. PaU^uUil Juiie 2S, 1910 /y /■ . rrt. l\ ft' /i /■■ ^ f " n \ i'lli. Z'.K ONE or THE MINERALS SEPARATION PATENTS. »Du(ll(>y H. Norris has several patents for the use of water contaliiinB. in solution, air under hi.Kh pressure for intensifieil hulil)ling, with or without oil. Wll \'l rr.()i'.\ri(i\ ' l.VI af,'itutioii, s.. .,n,.n .•nq.liiiM/rd, niiiy liav Imm'.i likr !„.■ slini thai WiiN jiiiiR'.i at III., rniu iuul kill,,l il„. piur,,,,,, f,„. jt ,„i,.st have done "n|ivll,.Mn,iMlH.i„i:n.,|i...,ls:,t nsi.lt..,! ,u .M.ra.M.M^' and ato,„i/inK '^ '"''«^' ^■"'""' ■ •"••• 'I'hr lat.T hist..ry <,( Hotatioii siiK^'.'sts that a day may .•(,ni.. wlic, tli. oil, lik,. the uuid, will be found non- .■s.s,.„l>ai, and in its ph.,-,. u.ll l„. a,| I th,. i.iir.v nt that sM,,ph..s the suhstan..,. n.-piiivd i„r niakint; l,iihhl,.s. To make l,uhhl,.s the surla.-.. tc.nsion ,.r th,. ual,r in th,- tl„tali,.n ....jl must !„. ,le,.i-eased \>y a e,.ntamuiaMt ami at tli,- sam,- lim,. tlie viseositv of th- li.piid nnist be Mn-n-tlien,-.!. Oil is not th,- only si.bstanee that ,.an p,-rform th,-se fun,.ti,.ns. Sn„i,. aikalin,. ,-ompoun,i may Ih- foim.l that will dojlu. tn,-k. In ti,,. CatL-rmoh-. Suhmm & i'i.-anl patent {V. S. /77,274> a fatty a,-i,l is pi-,,(!n<-(,| in .ntn. hi another patent by Sulman. (ireenway & lli-'ins ( T. S. '.n\2XuS) a elaim is made foV an ..rtranie eomp,)iin,| ,-ontain,-,l in .solntion in the a,-i,lill,.d wat.-r" as a soluble frothinjr a-ent. In I'. S. l.()r,r,.4!ir,, S,-hi,-k elaii.is the us,, of earbon teti-a-,-hl,>ri,|,- to i).-omot,. ' lcvi-ati,)n,' or Hotation. In I . S. TTO.tif)!), Seammell emj^h.ys sulidiur dioxide as a means for in,-n.asintr th.. viscosity, an.i in U. S. 744.;{22, Foote uses slaked lime Amonjr other nostrums, ah^ohol. ,>henoI. eamphor, amvl ae.-tale he.izoic and laetie a,-i,is. an,l eah-ium ,.hlori,ie have be,.n" suggested 111 various patents. In s,.me <.a.';..s. possibly, an ingre.lient of the ore 1I.S..U may sufli,.... M..ainvhile th,. element of time ,-s,sential to a good tonnation of froth siiKg,.st.s that the delav is u.seful in inereasing the viscosity, Mere speed of agitati,.n and aeration .Lies not seem to .sufTu.e. But sub-divi.sion of th,. air helps. This reminds us that T. J. Hoover and Minerals Separation t,)ok out a patent, in Oreat Britain in 1010, for the intro.luetion into the oiled pulp of air an.l other ga.ses through a perm,.able medium, but it was not emed w..rth while to obtain a patent in th,. Tnit..,) States. Knowing nothing about tins, J. M. Callow hit up n the same idea and designed the porous bottom now in use at many flotation plants. Cattermole u.s,..l an ordinary eone or fiabbett mi.x.'r' titted with baffles. Fnunent empbiye.l a mix..r of the egg-beater type. Sulmaii & Pieard in one of their patents (V. S. 793.S0S) sugg...st an agitator ma.ie of a eoi] of perforate,! gas-pipe, through which compressed air and oil are fed. Centrifugal pump.s. Pachuea agitators, air-jet.s. and pans with mechanieal .stirrers luuv been adopt,.,! by various !!>v,.!..tn|.^ (Mh^j, devices for .-ausing agitation and promoting aeration of' the puhj Iiave been, am! are lieing. introduced. "See FiK. 41. l.')4 TlIK FLOTATION I'KOCKSS SURFACE TENSION AND SALTS IN SOLUTION I From (h,. Uoio/r/ n,„l Srimtifir I'n'.sa of Octolmr y, lyir,, 'I'lir Kiliti.r: Sir— In .Vdiir c.litori;.! (,ii 'Fl„tati,.ri iit Itrok.i, I|.|r ,„ v,)m- issii,. M S,.,,toinlM.r 4, l:)l.-,. ,,ai;,. ;14.{, y,,,, ma,|r a statnucnt n.^^Mnlinj; siirlac.. trnsinn that is ratli.T licnwinir f. a sluWrMt of riotati,m It, IS as lollnvvs: ••Mr, llrhhani says that th.. sinfa.-e tei.sio,, was iMnvrs,..i l,y the salts iiitrod- ;,1, hut u,. venture to outmost that tlic op|>ii.sitf was the fact." Surfac." tofisioM lias Im.mi tlin-sh.Hl .,ut |iretty thorouplilv l.y articles appearing in the Journals of the A.neri.an Chemical Society, I'cfjinniiij,' in IHOS. •leiir. Am. Chilli. Soc, Vol. XXX, No, XXXI It, XXXV. ;!, Miirtli 7, July 3, March "), May 7, July 10, Octoher November December 11, 12, 190H 1908 1911 1911 1911 191.3 1913 1913 These articles deal with the drop-wei^'ht method (Weight of a fallini; drop,! for the detenninatiou of molecular weight, critical temperatur.-, and surface tension, and they descrihe the apparatus used. The work «as started hy Morgan and Stevens, who wi.shed lo investigate what had become known as the law of Tate. late, in 18(J4, had made a generalized statement about the relation of weight of drop to diameter of tube, the weight tliat eould be raised liy capillary action, and the temperature of the droj). Some of their conclusions are that : u;i The drop-weight of any liquid is proportional to the di(.meler of the droi.ping-tube. These tubes are iinifrom in diameter, thus dithering from the ordinary burettes. (b) The weight of a drop, other things being the .same, is propor tional to the surface tension of the liquid. (c) That it is possible to calculate the temperature at which the drop-weight would become zero, namely, the critical temperature of iiie Jiquiu, for at liiat [loint the drop would disappear, there being no distinction lietween the gas and the liquid. In tlie course of these experiments the surface tension of a number ■SIKKACK TKN^ION A.sr) SAI.rS IN sou TION io:> olorKUiiK; li(|iii(ls in a'..I57 0.750 41.247 1.000 37.031 1.500 32.504 2.00O 28.6i>7 2.498 25.72i; ^— Act'llc acld.-^ ','e Sur. ten. 0.000 71.030 1.000 07.750 2.47.- 03.995 5.001 59.435 10.010 -.3.500 14.980 49.451 20.090 40.455 49.900 37.109 79.880 31.026 100.000 25.725 h IS to !)e noted tl too I.'JOO 2.500 5.000 10.1100 15.000 25.000 50.000 75.000 -.00.000 lOo.OOO Korniic arid.— > Sur. ten. 71.030 22.296 69.816 08.024 05.706 62.061 59.197 55.190 48.112 41.990 35.281 liiit in all eases the very iirst addition eauses a very considerable lowering of surface tension. The decrease in the surface tension of water caused by Ijie addition of a very small amount of amyl alcohol is especially striking. Thus the presence in solution of even s ,..,.^. ,.!• .^..\\.^ ... ,-.. . water. ti.'.' a. 'ill hy hydrolyis in iL-Kis iiiay i,ui.-,c iiicir n.'ijaiive .ift-.-t .m -1 KKACK TKN.-ION \M) SALTS IN SOUTIOX l.")7 All acids lower surface tension, and in tiie ease of the laltv a.-ids experiments have shown that the louvrin;,' is proportional "to the carbon content of the acid. It is sufTir-'strd in th.-s.. researches that tlie surface tension of a o s /o /s 20 as 30 S5 ^h> ^S So SS Fio. 31. solution of two salts one of wiiich raises the surface tensi..n and the other lowers it, is an additive property of the two solutions— provided no chemical reaction takes place between them, and the values of the two are not far removed from the value of water. If one of the solutes causes a much larger etfect than the other, the value of the mixture lies closer to the one with the greater etTect. Kegarding the variation of surface tension with temperature It is made clear that surface t<.nsioii increa.ses witii decrea.se in' teiuperaturr In revi, ,ng the subject of flotation in one of the mining journals alKint tvr, vars ago, a leading educator made the statement that heat nicreas(?s surface tension. Now this is absolutely erroneous in ca.s<. of pure water and it is not likely that it would maintain in any cas<.. I do „„t mention this in a fault-finly n.,w f-. bin, In the work in th.- chemical j.mrnals the surface tension of pure water is taken as 71.0.} dynes per cm. at .■!n^ 09.;^.'} at 40°, and 68.46 1;> TH»i KLOTATIUN I'UoCKSS at i.> . While IIo(,v,t; u.s,.s ,s1 with a(.ol„^.i..s. Again Hoover makes ji sli,. o„ pa-e M «h,..v h,. says tlu.l surfare tension of water has '•■•■-' . .■t.M'.niMed to In. a foree of SI dynes prr s<,,ia,e eentin.etre. Mere he has eonfuse.l snrfaee tension in dynes i.er eenli.netr.. with Miilac-e en.Tcry .n •>,-« per s.,, en,." Work ,in ergsi is the a.t „f I>n..l.u'ing a ehange in oj.position to a foreo (in dynes, that resists tins .-hati-e. Now, ^M-avity fiives to a -ram a veh.eitv of !IS() en, i.rr s.-on,l. It ,s th.Tcfore equal to !),sO dynes. Ifenee if one frra.n !,.■ I'tt-a vertu-ally one ...ntinietre, tiie work d.,ne against gravitv is !'N> er-s. Hooks on j.hysi.'s .hMHonstrate that surfare tension (dviies. per u.ut-WKlth IS rninierirally equal to surface ener• ".■ntunetre, and snrfaee energy in ergs per square eentimetre. Ihe ahove figures on surfare tension and surface energy ini"ht I'o apphe.l to the so-ealied surface tension nietiiod of flotation such as the Wood machine, wh,.re the ore is fed drv onto the surface of water and at one place at least, in the West, wlu^re the wet oiled j.ulp is spread uimn the surface of water in a spitzkasteii While 0.0724 gni. (71.();{ : f)81 ^ per sq. r>„. represents the weiHit that It requires to just break the surface inemhrane of pure wat^'er ll.rre IS anotlu.r factor, and that is the sixe of the diniple formed' lake the .^ase of galena. The huoyant far,„rs are the membrane and the water displaced. Taking the speeiiic gravitv of galena at '.5, the maximum volume of a dimple mi (mr sipiare centimetre woul-i: be 0.00% cr. (0.0724 : 7.5, or a displacement equal to O.OO.tG gm. water. Adding the two quotients we lind that 0S2 . 11.0724 + 0.00!I6) gm. galena per .sq. cm. would just break fhivu-'h" This IS not mathematically correct, but a clo.se approximatioii-- sufficiently ..los(>,t becaus.' we do not know the volume of the foreign water attached and the condition of the water. VA Pa.so. Texas. September 24, Will H. Coghill. t'Concentration of Ores liy Flotation,' 2nci rijition tSee page 348 of this l/ook. ,-.; I '•'f-y'??:; AIK-KKOTH FU)TATI<)N If,") AIR-FROTH FLOTATION (From the Mining and Scientific Press of October Hi, 1915) A LuiAL N'KJiSlON ijy Tilt; TkcHNULOIIY of TUE I'liOCKtS.S lllerewitii we give ii part of tlie address made l)y ilr. Walter A. Scott, counsel for defendants in the case of .Minerals Separation v. Miami recently tried at Wilmington, Delaware. We give this not only because the learned gentleiiian discusses the underlying principles of the flotation process in an interesting way but because the (piestious put by the Judge are such as would suggest themselves to other persons curious to understand the subject. In reading this excerpt from the court proceeilings o'lr readers must not forget that It is an <., paiir statement, putting forth the technology of the subject with a view to aiding the ease for the defendant. Mr. Scott assumes that oil is necessary to tiotation and also that the force of surface tension bursts the bubbles. Neither of these assumptions can he taken for granted in a seientilic discussion however useful they may lie in a lawyer's brief. — Kdituk.] The manifestation of the force of sui face tension is a phenomenon that shows itself as a tendency of any liquid body— we may confine ourselves to a liquid— to assume that shape in which it has th- least surface. It is a well-known fact that in the form of a sphere the ratio of surface to volume is at the minimum. Therefore we can say that surface tension is tliot force or property which tends to .•anse a body of li(iui(l to assume the splieiical f.rm, in order to make its surrounding surface as small as possible. We are fa- . ..ar with manifestations of this force; wiien a drop of water falls upon a hot stove, we see it immediately come into the form of a little sphere. The explanation of that probably is that the stove, being hot, generates a little steam all around tne particles, and that frees it from '.nterference by other forces, so that it assumes the shape which surface tension tends to give it. I think the ordinary shot-tower, where molten lead when poured or droppe.l a.ssumes the spherical form of shot is probably another manifestation of surface t.nsion. The lead, in.stead of dropping in a formless mass as it presses th-ough the air. under the influence of the contractile force around its surface is drawn iin into a spherical body. Another illustration is the tendency which we obse-ve .vhon water 160 TllK FLOTATION I'HOCESS IS spillr.i, ue will say, upon a smoi.tli smtaw (,r tal.lo \\\nx- it not lor swrla... tension ,t uoiil.l .snr.a.l out in ai, inlin.tdv thin lavor- gravity would tend to pull it down tlat. But surface tension ..mses It to assume the lonu of a littl.- l,ulf:e of water .,n the tahle. Vis,.„sitv 01 the water ].rohahly also plays a part in that. It is diilieult U> .iKsentangle all of these eaus^-s. Hut surfaee tension surelv ,s one ot the torees to enter into that eli'eet. Now, tliis surface tension exists not only at the free air-surfaee (lor instance, the surface of the water in this glass, hut it exists at every point where there is a change of nidiuni, that is where tlie water encounters another suhstance. Surface tension h.re is along the uater surface, the air surfac... hut that surface tension e.xists clear around the inner surfa.v of ti,e gla.ss and at the hottoni ol the glass; it luus tl,e sa.ue rehition to the water around the glass and at the bottom of the f;lass a.s next the atmosphere above So this surface tension exerts itself about patents issue.l to seientifie men, teohnieal n.en. the offieials eonneeted with these eompanies. in whieh Hey also explain the use of hoth soh.hle and u.soluhle reagents l„r Ih.. purpose of eontributing etTieieney to a l)ubble or froth proces,s. Notable among tliose is patent 78,S.247. wiiieh is in evidenee Patent 7S8.247 w.s grante.l to Cattern.ole, Sulman, an.l I'ieard Sulman and Pieard are two „f tlie grantees of the patent in suit' Sow, in this process-- TiiE Coi-KT (interposing) : What is the date of that patent? Mr. Scott: The date of the grant was April 2r.. 1!)05- the diile ot the application was March 2f». 1004. In their statement of inven- tion in pat-ent 788,247 tiiey say: "Our process has for its object the separation of minerals from sdicious or earthy matters of ores by nleans of soaps Tr simil. • xhihr. -^ "'"^- '' '^f I><;"^^«:'t "P"» the superior physical attraeti^ exhibi e.I by minerals for fatty or resin acids, or for certain othS annnatie denvates, such as phenols, cresois, etc., which form sol u We salts or compounds with alkaline hydrates." soiunie Then upon tlie first page of that same patent they state: "The mineral particles now attached to or more or less coated or enclosed by films of fatty or resin acids and the like, arc eapaldo of being separated from the gangue or earthy parti des by Various methc Is depending upon this altered phv.sical eondi fon For example the coated .nineral particles may he removed by generating foThe'fattv or '" "-f '"'■''"■"' "'"■',■'' P-t-erentially attach ES v ! to the fatty or si.nilar acid coate.l particles and raise them to the surtace of ,he pulp, whence they may be removed by skimming ol- There is a clear statement of the use of soluble agents, the verv soluble agents uhich are mentioned in the patents here in suit with their us... in connection with gases for raising them to the surface and the only way in which a gas can function is as a bubble a.id this effect of lowering the surface tension was there brought about by the same substances which are in use today. In patent 793. S08 uliieli ia t>>„ ,.„<„..♦ ,i:„",i._:.. „ ,, „ . spiral coil that we have had so much discussion about, the patentees state : "The present invention relates to the concentration of ores by Kil ■INK hlDTATlilN lltu(l>.'- M|>ar,-,ii,,n ->l Ih.; in,.t;illitVn.i.s .•..nslitiimts .-n,,! -nipliitr. rnr\,uu Nulplnir Mild tl„. lik,.. fn,i,i thr '^nw^ur. I,v „„,,„-. „f „ils .-n,,.,. tiir' "I- Miiy Mimlar siihst.-in.-r uln.li l,;i. ,-, ,,n.r.. ivnti,-,! Mtlinitv i,,,- i,i,.|iil' liti'i'oiis iii.'ittcT liver ^'iiiii.nic." ''"'"■ •■"' ""•'■'■ iiirnli,,n,d is f 111,, sul.sliiiirfs in ilsr tndav <'(ml-tar is tlu' pnii.ipal sniuv... I think, of ph.-iinl aii.l .•.vs„l, aii',1 Jt IS us.mI in a rni,!.. stale in flotation .operations. I Ijiink it is one N. 7:3.303 H I. SULMA.N i H. r. KlhKFATRlCK-PICA.RD ORE CO.SCL.STRATION. irfLlr*Tlrl riiiD o.'i ^ it ,, P.ME.vrrD .lUI.Y 4, l''i)i 1SBEET1 5wrr I'll-.. 33. MiK vy ' • ' : •*,/ HI (in VTHl ( (>ir r.VTENT. M2¥'-'M,^;^m^: ;y^\ <*• si-.%-%'!''C!iix'- 'X, mm liiiiiai AlK-KHUIll Kl,()T\TION 165 of the sulistaiiws whifli tlie misw..rs to tlie interrogatories say lias been used l.y the Miami coMipaiiy. It is partially soluble and' partiallv insoluble. If is a mixture. And then this patent, after naming these substances, oil. grea.se. insoluble substances, and then mentioriinfr in the .same breath tar. whieh is partially soluble an.) partiallv insoluble, the same as is the frothintr agent used at Miami, after e.xp'laining the use of tliesi' substani'i'S goes on to say: ••According to one method of carrying out our invention suitably .■rushed ore is snspende.l in uater. To this suspen.sio,, a proportio;, <.l >n\. grease, or tar (hereinafter referred to as 'oil'i is adde.l an.l m.iy mixeii \vith the mass by any suitable means in .|uantilv insuf- ticient to raise the oil minenil by virtu,, of the flotation power of !<■ 0,1 alone. .\ suitable gas is now geiierate.l in or introduced into ttie •Kixturc such as air, carbonic aeid gas, siilphureted hvd-o-ei, or the like. . ^ . Now here again we have a process in which a .soluble agent is use.l. Tar is not completely soluble, but the complainant has taken the position, which I will accept for the purpose of argument at present, that if any constituent of a substance is soluble, then the substance is a soluble agent under the second and third patents in suit. Accepting, for the sake of argument, this construction of these patents, we have here disclosed, down to the minutest detail, every operation that is performed at Miami. We have tar, a mixture of soluble and insoluble iiirents; we have the admixture of that substance with the pulp; we have the introduction of that substan.-e into a ves.s,'l provided at the bottom with means for the admission of air; that means being this perforated spiral coil. 2 p. III. Same da.v. Mk. Scott: If the Court plea.se. just l>efore the recess I was spi aking of the spiral coil-pipe machine, the perforated spiral, and had stated that this process wa.s identical with the operations at -Miami. In fact. I think it will 1... .lillicult for anyone to conceive of any different action on the part of air bubbles es<^aping through fine holes in a metal pipe or a sheet of metal, and the same bubbles escaping through similar holes in a canvas bottom. I do not think the thing needs any argument, the two proces.ses are absolutelv identical. An attempt has be.m made to establish the appearance of identitv '■'"■ -'^i^---' •''•i-isa o! :;iir)!,i,.s Viimii resiiiis from tiie -\liami operation and from the patent 793,808. and the persistent froth tb;it results from the violent agitation of tlie patents in suit. , „ *^-.^^^^:'mm^^^mm^ 1(16 TIIK H.OTATKIN runCF> Now certuiiily to the i-ye there is no idiiitity whatever. And t;oint? I'uitlier, looking' to liie real essenee of tlie two ojifnitions, we tiud as tjreat a distinction as tliere is in the a])iiearaiice. The agita- tion frotii resnlts from violent agitation of tin' pnlp, heatins,' the air into very fim' partiiles and then hrin>,'iMf; the li(inid to rest; as the (oiiit lias s<'en iiere in eonrt, wlien tiie atjitatiiifj niechanisni \\as stoj)ped, there arises tliis pei-sistent froth which hists for days. Kvcn wlien shaken in a holth- in aii'onhincc with the dirc'tions of the California Teehnieal Jonrnal*. we sliowed the Court a froth that had stood fti hrouKht h> rt'8t I'or this CDlicroiit frotli to rise. Now, it is tMiually of lliu < ssoiu'C ami vital to the process carried on at Miami that just tiie opposite conditions i)rcvail. In the process as carried on at .Miami the bubbles which carry the metal concentrate to the surface can ris*; and can exist only in the presence of these H«. 835,120. PATENTED NOV. 6, 1906 H. L. SOLMAN, H. F. KIRKPATRICK-PICARD & J. BALLOT. OHE CONCENTRATION. H-rLIOlTlOB FiLCD mT » l»'is I •lECTi aiEtr 1 7K ?t'iitlf (■iitrancc of tlicsc IiuIjIiIcs at till Ii()lt4iiii (if the vcsNcI is the (■(iiiivaleiit of till' violent ntritaiKiii whifh forms a vital and osseiitial element in the i)roee88 of the patents in suit. There a^rain to the eye there is no similarity and no .(juivaleney. In the agitation-froth pnicess of the patents in suit and they are all alike in the meehatiieal frcntment of the pulp liy as;itatioii~-\ve have a mass of water that is beaten into a perfect vortex or maelstrom, as violent a movement as we eari (•(ineeivc of; whereas in the .Miami process where the air is admitted tlirou^'li a permealile liottom. we have no more agitation than one would oliserve in a glass of cliarIace away from the agitating ve.s.sel. In the Jliami process the moment the influx of air stop.s— and air is what is contended to he the equivalent „f the a^ritation. that is, the incoming stream of air— the minute that stops in the Miami proce.s.s. the entire body of bubbles carrying the concentrate collapses. and I think your Honor has a vivid impres.sion of that demonstration in which Mr. Ver.xa and .Mr. Hunt first turned on the .lir in that spiral-coil machine, and in the canva.s-bottom machine, and huilt up this ma.ss of bubbles, and then suddenly turned the air ot^'. whereupon this all dropped. Now, looking at the matter of equivalency, it seems to be an impossible construction of the facts aiul law to urge that the incoming air-streams in the bottom of the permeable-bottom cell, whether it be the spiral pipe or the canvas bottom, is the equivalent of the agitation, when their action is precisely opjwsite in respect to the formation of the froth. In one case the froth forms only when the agitation ceases. In the other the floating or rising bubbles exist oidy while the so-called agitation is going on. The principle ,,f the two things is as different is the manifestation of that principle. The manifestation ditTers in this respect that I have pointed out. In one the froth rises when the agitation stops. In the other the Now as to the principle. The two processes attack the iiroblem wmmm^.m^'rym'^^^t -^T". AlK-KK(fTll FLOTATION lefi ill i-i>iiii)lttle attach itself to the mineral — below the surface or above? Mr. Scott : T think that must be below the surface, too. n1 ■TjT TUE KI.OIATION ntOCE.SS last as tlicy were iiiadr, we would never have any appreciable aiiimint of bulil'-s on toi>, They would simply break, each one in time for the next one to eoiiie uj) ; but as it is there is a small interval of time before they Imak. and more bubbles are being formed at a rate so rapid that some of those bubbles arc raised to the top and carried over the top before they liave broken, and that is the only reason that it is possible to concentrate ores in that way. The frothing i)roi-es,s, on the other h.and, is not dependent upon any such principle at all. The thing is simply agitated violently, and when the agitation stops, this froth rises and floats much the same as a board would. It nuiy not be as long-lived as a piece of wood, but it la-sts for weeks, and it simply rises there and floats. Speaking with r gard to the purpose of concentration, it is permanent, within the limitations that pernuinency is necessary or desirable. Now in view THK CoLUT: Let me see if I get your idea. Do you draw a distinction between a process which results in the formation of what is termed a permanent frotii, and a process in which the bubbles come up in rapid succession, but not in such quantities or in such close proximity as to form a permanent froth, but as soon as they get to the surface tli.'y float away; is that what you mean? Mr. Scott : Tiiey float over, if we get them over before th»y lireak. Jt is a kind of a race. TuK CorRT; If you get th< m over before they break! But suppose they break before you get them over, what becomes of the iiuneral ? Mii. ScdTT: Then, as is shown in these demonstrations, if they do break, the mineral drops, and it \a caught by the bul)bles below. TiiK CofiiT : And brought up again? Mr. Scott : Atid brought up again. The 'nubbles must- lie brought up fast enough st> that it will graduall;. be raised. Tin: f'oiKT : That is, above the surface, Mr. Scott : Yes. There ii^'ist be new bubbles coming fast enough so that it is gradually carried up over. TiiK f'orRT: And they float off? Mr. Scott : And finally float off. TiiK ('(HRT: That is what I meant. I did not express it in that way. You cxpres.sed it ii, two stages, a first jna.ss of bubbles and a succeeding mass of bubbles, but that was what was in my niiiul, Mr. Scott : The same idea. I think. AIK-KKOTK l-l.oTATInX The Couut: Tliat tlicre is no pcriuaiiciK'c ? Mi{. Scott : No permaiifiice iu the Imlililc process at Miami. Now, if the Court reiiiL'iiil)ci-s the mass of hulililes was probaJ)ly about a iiiL-lu's liigh ahove the water, as 1 remeuibei. Mis. Kionyon: Ten or twelve iiiohes lii^'li. Mb. Scott : Ten or twelve inelios hiph. It was quite hi5?li. Now, if a partiele should be allowed to drop by rea.son of the bubble breaking, it ivould be caught on a bubl)lc below, aiid tlius constantly raised up by new bul)bles cominf,' into the bottom, so that it is, as you might say, a cas<; of stepping back an inch and going forward two inches, and gradually getting over, despite the breaking of tl'<> bubbles. The term 'flotation' .seems inaeeurate as applied to this Miami proces.s. In tb agitation-froth process, after the agitation is stopped, this froth actually does float. It will float for hours, and days, and wwks, and stay on the top of the water; but in the Miami proces.s, as soon as the incoming current of air stops, everything drops, and we have the clear water-surface on the top of the cell. Now, that demonstrates absolutely that that mass of bubbles several inches deep, which we .see in the Miami process operation, or that of the patent 793,808, is not really floating, [t is held up there by the current of air, which holds it in place. That current of air not only manufactures these bubbles so fa.st that we have that mass of bubbles there, but it actually holds them up in position, and the minute the air is turned off everything drops. The mineral goes right to the bottom, and the bulibles break. So that instead of a floating ma.ss of ••oncentrate, it seems to me that it is liest described, as I think I did once before in opening the ca.se, by saying that this Miami operation io similar (o these devices we have seen, where a stream of air is blown out of a pipe and a ball floats above it. The minute the stream of air is turned off the ball drops. In pojndar language, we may say that that ball is floating in the air. but obviously that is a mi.snomer, if we attach any e.xact meaning to our words. Now, the Miami process is analogous to this ball held up on that stream of air. The agitation-froth process is the ball floating i' the water. The two things operate upon absolutely differen* principles, and the ditTerencc is so great that it cannot escape anyone's notice. Dr. I.iebmann has characteri/c i)articlcs; so that at that stage of tiie operation we have in the water a series of bubbles with the mineral paiticles sticking to them and we have the gangue particles free in the water itself. Now, thos<^ bubbles rise, of course, by gravity and carry with them those nniieral i)articles. The combination of the nubble and the mineral particle is together lighter than water, .so it goes to the top. TiikCoikt: I understand. ^1r. Scott : And the gangue particle has had no assistance what- ever from tlie air. It is still heavier than water, the way it always was, and it goes to the bottom. The Coi'RT : I understaml, then, that i' the Miami proees-s bubble attaches itself to the mineral beiow the surface. Mr, Scott : Helow the s\irface, yes. The CdiKT: Aik' carries the mineral — AIK-KROTH KI>()T.\TI()N 173 The Court: And it carries it up, does it? -Mk. Scutt: It cairies it up to the top. The Court: Is it not pretty much a question of froth, rather tliau of concentration — tiie difference between the two processes? 1 understand that the purpose of the patents is to eflfoct not a frotli, hut a concentration. Mk. Scott. I'recisi-ly. The Court: A separrtion? Mr. Scott : Precisely. The Coikt: Now, you may assume tiuit I do not liiiow anything about this. I want to iiave it put to me as plainly as you can express yourself. What is the distinction in principli' between those two processes? You have explained the difference in point of actual o[)eiatioii. \ow, what is the distinction in principle, when it comes to the foniiulation of any principle, between these two operations, as bearnig ui)on the (piestion of the separation and saving of the metal particles? Mk. Scott : The broad principles are the .same in lioth. In both we lia.c the pulp, consisting of ore held in suspension in water. In both the water is modified to lower its surface tension. In both the l)uoyancy comes from air bubbles. The difference comes after the air bul)l)i"s have attached themselves to the mineral particles. In the afritation-frotii p-.x'css the air is beaten into very minute bubbles, and when they rise with these mineral particles they form this permanent froth. The j crmanent froth is then floated off or skunmed off. Now, in the Miami process there is no beating up of tlie licjuid. of the pulp. The bubbles are larger and more fragile, and instead of forming a permanent froth, whicii vill float, the thing is simply pushed off by the current of air. The basic principles are the .s;ime in both of them. The method practised at Jliami is the older of tlie method's. It is the method of the patent 793,808, with the perforated spiral coil. Now, speaking so far as patents go, departing from the Court's "minute film." t[lhr roil-piiic iiatcni (No. 7n.'?.S0S i is d.itPd .Iiil.v 4. 190.->. l)ut tho applica- tion was filed on October .■.. iW?,. On ttio other liiind the l)asic agitation-froth patent N.I. .S.'!,'->.120 is dated November fi, WW,, while api)lication for it was made on May 29. 190.').— Ethtor.] WHY IH) MINFJiAI.S Kl,OAT^ 175 This brings 'is, of course, to what I regard as the only real ques- tion in the case, and that is as to wliether there is any distinction in principle between the frotii wliich is formed with a very small quantity of oil and one which is formed with a larger quantity; in other words, whether there is a diflferenoe between an air-froth and an oilfroth or emulsion. The first patent in suit, 8.'jr},120. states 'het less than 1% of oil is us( d ; and then in describing the action of that oil it states that it coats the mineral particles. Well, they cannot he coated otherwise than by a miimte film. The descriptive language is pre- cisely the same, and then, as shown by the demonstrations in this Court, we have produced the same result ocidarly, and nietallurp ically. with these large quantities of oil as with the minute i|uaiititv. WHY DO MINERALS FLOAT? By Olivek C. R.»lston (From the Mining and Scientific Press of October 2;i, 1915 » *I was very much interested in reading an article by Charles T. Durell, ai-peariiig in the Mining and Scientific I'nss of September 18, under the caption ' Why Is Flotation ?' However. I fiml myself unal)le to agree with .Mr. Durell'ti line of argument, and for the following reasons : In the first place I believe that Mr. Durell has used loosely s of further data we can let it |>ass. My main comment is that while ^fr. T)urcll believes that the only function of oil is the toughening of the surface film, we are not sure ■iM. ,< S. P.. Sept. II, 191.-), pp.pe S.SH. l7^ rilK KI-OTATIDN I'KOIKSS thai su.-h is ilu. nisr. Mis liypotlic.sis iiLcmt ••na.sr,.Mt " Kas and '•"'■.•liidcd" tras decs iiol iv(|iiir." 111,. |)nsri„'(. of oil ; l„.,i,-,. lie lias had to r\|)hiiii the lis.' of oil op aliaiidori the liy|iotiicsis. Althoujrh I .■oiisidrr th.it .Mr. Dinvll should 1.,. api)laud.Ml for his foiirat;.' in piitliiii,' forwanl a hypothesis coi riiiiip a siihj<.ct that has hocii of so enipiriral a iiatuiv up to dale, n.^wrtheless I have felt the ueeessity for .■hallei.-iiifr .Mr. Durell's hypothesis fuid of taking the liherty of advain-iug what weiiis to me to he a better one. There are two siicii hyix.tlies-s wh'eli seem to he e(|ually possible and it is not .-rlain l.iit that th.' two simply eover parts of a frreater fact. One liypotliesis can he stated in terms of the iiiter-faeial ten- sions involve T,,..„, -f T,.,^) the .soli(' powder will remain suspended in the water. ^KoUoiit ■<,-ils( hrift. l:'.:2?,5 and ChCm. Wefkblad. 10:700. ■Encyclopc.lia Britayuiiia. on 'Capillarity.' WIIV IH) M1NKKAL.S KU) AT .' 179 'f T,,., > T,,.„, -\- T,„,,, the solid will leave the water and ro into tile layer of oil. Il '',w,n, > T,,,,, -f T,,.„,, or if none of the three tensions is Rreated than the sum of the other two, the solid partieles will eolleet at the boundary hetween the oil and water. It hardly needs to he said that here we find something very close to the conditions olitaining in the flotation process. In faet, the old Klinore hulk-oil flotation method fulfills exactly the conditions that Keinders had in mind. Helow are piven some tallies of results obtained by both Heiiiders and Hoffmann'' in an experimental way, by sus- pending u definite pondered solid in water, aduinj^ a second im- miscible litpiid, and shaking. The Ictt.r ic means that the powder remained in the water; the letter it means that the powder went into the oil layer; the letter .v mci .is tliat the powder went to the surface 8<'i.arating the oil from the water, and .symbols like s{w) or s{o) mean that there was a Rood deal more of the powder in the inter-face than ill the bracketed phase. Similar residts were obtaiued with ciilloidid solutions. Tvm.E OK Reinokks' Rksilts Paraffin Ani.vl Water and oil. alcohol CCl . Uenzene. Ether. J^^o"" w w(8) w(s) w w(s) •^^l""- ws ws w(s) w(s) W(8) <5>l'Sl"" W ws W 8W W8 KaSO, w(8) ws ws BW ws •Magnesium ws ws «8 ws ws ^^^ 8 8 8W S SW Malachite so s s s sw 2nS s 8 s s SW ^^^ so so s 8 a Hgl.. so S 8 s 8 Carbon so s s s s Selenium so so so s s Sulphur so so o(s) so s Ilotrmann worked a great deal with ehemieal precipitates and other artificially prepared products. However, the laboratory method in- volved ou,;ht to be good in the study of flotation processes for a pos- sible method of floating o.xidized minerals. Then it might be possible to convert a successful bulk-oil process into a frothing process in the same way as the old Elmore bulk-oil method went through the stage of graiuilation and elassitic;ition to a final frothing process such as we 'Zeit. physik. Chem., S3; 409, 1913. Ihd rnK ha>tation process Taui.e ok Hokkmann'm Rh.sii.rs Wal r . ('..SO. SllO AIMIll hnS H.iSO, ZllS Zn(J CaCO M^-iOM A I HafO CiiS I'l.CrO, ,SW „ SCO today. I liavp done some work filonir thcs.. lines and liavi- planned eonsiderable reseaivli work in the Siune direction. Meantime these notes might a.s well he availahle to others in suKpesting lines of ustd'ul research. The comments to he made on the al)()ve tables an> without end, hut the tables are given here mainly to suggest the j)o.ssil)ilities of further work. The question arises as to whether it might not be pos-sible to apply a set of ine(iualities such a.s those of Keinders, or oven to apply Heindei-s' ine.iualities dire.t, in the prediction of results for froth flotation. In froth flotation we have at least four phases — solid, water, oil, and gas— unless the oil happens to be solul)lo in water, in which case we are reduced to a solid, a .solution, and a gas. Wo have inter- facial tensions between each two of the pha.ses. making si.\ tensions al- together, and mathematical expressions covering such a ea.se must nece.s.sarily l)e much more comple.\ and exhibit a greater luimber of possil)ilities. The problem is more difficult, b\it it should be capable of solution. Fig. 35 shows a fanciful magnification of one possible arrangement of the i)arti<'les of sf)lid. droi)lets of oil. and si)hcrules >»^-^-r^ WHY 1H> MINKKVI-.S HjIAT.' 181 of iiir, it) till- li<|iiii| <>( the orc-piilp, Im intf siiliji'di'd lo Hotatiiui, at tlif iiioiiiciit wiii'ii a l)iilil>li' lu'iriii!* I" niiM' a particlr ol' niiiHTal to tlie siirfaci'. Fif?. .(() sliows a pDssililc way of applviiitf R<'iii(ii'rs' iii('\T E H M I rj t R A L " Flo. 36. Fig. 37. until it forms a film only one or two molecules thick. This fact allows an explanation of how the small amount of oil used in the froth- flotation processes could be sf) efficient. If it so happens that the oil ■M. it «. P., Sept. 11. 1915, page 167. -i.f'.; ti^^t/' -:% -»...^U ^ vu^i*-^T/r;: vi*A.,cA;;^''.h^>r.tf^^ ^■■^ •w-*»v--* .--1 <■ ^'^(j ^z-. -<(,- ?'^' .tt'3 ^M:^^Mmi^Mm^t^ssi^f^s^s^s^^^ MICROCOPY RESOIUTION TEST CHART ANbl u.id ISO lEST CHART No 2 1.0 I.I U^ms 1 2.5 ■32 3 b I: li£ 12.0 2.2 1.25 1.4 _j -IPPLIED IfVHGE Ir " yj ^ -feel "esler. Ne, fork 14609 USA ^) 482 - O300-Phon» 182 TIIK FLOTATION- I'HIKKSS uouhl coat tlie inner siirlai-L' of an air huhbli', tliu powdurtd mint nil would he abl.' to take up a position on the inter-faec between the water and the oil witliout any reference to the air in the bubble. By reason of the known low adhesiveness of oil and wal.T il is doubt .'ul if the air l>ubbles eo\ild lie completely mantled b\ oil, as tiie oil would be too liable of its own weiprlit to slide down to the bottom of the bubble to the position indicated in Fig. ;i7. Even here, the oil could <'arry mineral on its water interface (in ease the oil and water do actually get into contact) and Keinders' criteria would still ajjpiy. Ill a Callow flotation machine having glass sides it is sometimes pos- sible to see particles in ju.st such a position. However, this ease does not prove that the top side of tlie bublile is coated wiih oil or mineral, wliile the bubbles of a mineral frotii on top of the pulp are seen to be covered eomi)letely with particles of mineral. If the mineral tends to enter the oil phase completely and leave the water, llie mineral grains present only an oil surface and in case oil droplets tend to collect at the inter-face between water and air tby Keinders' criteria) we could have the ease ilhisf -'at'd in Fif. :iS, Fki. 38. This ca.se, as well as the one illustrated in Fig. ;U!, would allow of the air liubliles becoming completely covered with oiled mineral. Other phases are possible, but these are given to show how very feasible it is to get an explanation of flotation in terms of inter facial tensions. In an investigation i-ondiicted by the .Minerals Separation, the 'enntact angle' of various minerals with wafer was examined to tiinl at what angle the mineral Iuk' to come in contac' with a water siirt'ace befoiv it was wetted and could sink." A glance at Clerk Maxwell's «H. L. Sulman. Trans. Inst. M. & M., 1912. WHY no MINF.KAI.S 1L(X\T .' ]S:! I'aiiious paper on 'Capillarity,' upon whicli KciiKJcrs' work is luiscil, Avill sugjrcst immediately the explanation of a contact angle, and that it is the result of a certain equilihrium of intcr-facial tensions of air, water, and solid. Valentiner" ha.s likewise investijjated the contact angle and its hysteresis under certain conditions and has con- nected it very definitely with capillary phenomena. There can be no doubt that there is a chise parallelism between the angle of hysteresis of the contact angle and tlie ability of a mineral to tloat. Hut if we go no further than to observe the parallelism we cannot designate the statement of the parallelism as a theory, although we might bo able to predict by its means whether a mineral would float. To go into this a little farther, and indeed nh.ng the line suggested by ;Mr. Durell, we ought to consider the properties of the surface layei-s of the substances involved. For e.xa.nple. the plane surface of water in contact with air is known to have considerably different properties from the inner bulk of the water. Tn Fig. nil the film is Ji'fr^C£ f'/LX or i\'\Te.R BUL ^ yy f\T E R Fio, 39. shown magnified in thickness. It acts like a tightly .stretched elastic skin, due to what we have long called a 'surface tension' of 81 dynes per centimetre, as is u.sually given in text-books. (This means that for a strip of the surface film one centimetre wide, a longitudinal tension of 81 dynes has been measured at ordinary temperatures, and there is a definite tension for each temperature.) This tension of the surface film is one of its most connnoidy known prop(>rties, but some other interesting points about it are given in tlie following: Its thickness, varying with temperature and other eunditions, has been estimated'^' to be all the way from 4X1"'' to 10 * em. Its density averages 2.14 as compared with 1 for bulk water, although it is doubt- less mure dense at the immediate surface next to the air and gradually »'A Theory of Flotation.' MctnU iind Erz, 11:4.t."i, 1914. '"Philonophirnl Mngozinr. 20:502, 1910. 1S4 Tin: I'l.iiiwTiDN rnuciv- sluhirs i.ir into tliat (if liulk water. 'I'his (•(insidcnitidii i.roliahly ex- plains Mic' nidc varialiun in the results of tlie ineasinvn:ent of tiio tliirkiies.s, as one rnetlidd niire density, how- ever, is illustrative of the ujaL'iiitude of the force involved hecauso water is a siihstaiice that resists compression, and it has heeii cal- culated from the known comprossihility of water that the force necessary to compress it to twice its (U'dinary density is some thousands of atmospheres. Such a eompression should liherate heat. and. in fiict. the heal liberated when a definite area of new surface film is loriui'd has been measured and found" to lie 0.00:]].") ,.;d. prr si|. em. Hi'in>,' so lii>:lily compressiu. its siiecilic heat ini^dit he expected to he ditVereiit from that of hulk water and has been measured as heiiiir nearly 0.4.') instead of 1. This low speciiic hrat approximates that of ice. One imj)ortaiit property of this lilm is that it will often take iij) ilissolved sulistaiices in difl'ereiit proportion from the amounts in which tliey are taken up in tlii' hulk solution, and there is always a definite e(|uilihrium hetuc^n the two. This is known as surface eoncentratiou or -surface adsorption.' and has heiMi dealt with mostly in colloiil chemistry, where the larj;e amciint of surface of the finely divided solids is lar-re in .•omparison with their weii,'ion. All the tech- nical liandlinic ••liiirges. due lo various iihinations of .ctors which atVect the douhle electric layer of the inter-facial tilnis. Since the size of iiiiuiy of th.' j.articles of minerals tr.aird liy dotation is of the same niap.itnde as that of many colloids wu cannot esc;ii)e from calliii},' oiv-slime •'coarse sasj.eiision colloids." and mu.st apply all the laws of colloid chemistry to our problem. The (deetrif charges on siispemled pa-ticles allow another possible •■xplanation of flotation |>lienoiiiena. We find in some of the e<,lloi,I chemical literature'' that i|uartz particles when .su.spended in waler are negatively charged, pyrite partich'.s [x.sitively charged." oil drop- lets are negatively charged, and air hiibl.les negatively charged. '■• The charges are .somewhat small compared with the weight of the partiides, so that they are hardly strong enough to cause negatively- charged quartz to stick to positively-charged pyrite, as they can have only a few i)oints of contact, and currents in the water could easily tear them apart. However, the negatively-charged tiroplet of oil, which is repeUed from a negativ.dy-charged particle of .piartz, can wrap itself around the positi\ely-charged pyrite partiide so that they will stick together, and the same applies to air hubl.les. The other sulphides known to be flotative have positive charges when suspended in water or can be made to assume positive charges by the use of flu- proper amount of the proper electrolyte. So it can be s.>.'n that the applicaHon of the.se principles gives no difficulty in tion. The underlying cause of the tensions and of the electric c'liargcs is the same thing — some strange molecular, atomic, or other force manifested in 'adhesion,' "cohesion,' or even 'gravitation.' if you [dease. >.'() one can claim that electric charges carry the whole explanation of Hotalion. nor can it he stated that it is merely a ([ues- lion of a Irdancing of inter-facial tensions. Hoth will douhtless have to he considered. Although much more could lie said on the sulijcct, I have only atleinplcd to point out that there are certain scientilic princijiles that can he ap|)lied to our problem, with great chan.ees of success, in bring- ing us nearer to a definite understanding of flotation. Physical chem- istry has been a recognized tool of metallurgists for some lime, al- though litth^ used by most of them, and now a particular branch of phyr,ical chemistry — colloid chemistry— is beckoning to us alluringly. -Ml (pieslions of the treatment of orc-slime should be stuilied in this new liglil. The results of aii apj)liiation of tln.s idea in our own laboratory have been astonishing, and we hope that we nuiy soon be alilc to pnMisii them. WHY IS rKdlATION .' l.s; WHY IS FLOTATION? (P^oiii the Miiiiii;/ (111(1 :S(.tfiitilic Press of Otloher 30, 1915) The Editor: Sir Mr. Durcll's article on this subject in your issue of .Septem- ber IS is interesting'. I helii've that an exchange ol' ideas on this subject is very desirable, and it may be tiiat some of the information that 1 have collected may be of interest to the readers of the Press. The arguments which .Mr. Dun'H's article presents are, briefly, tiiat tioatalilc particles eainiot attach themselves to previously formed bubbles, but nuist be floated by bubbles which form themselves on the surface of the particles so that there is no surface film of water between the particle and the air. To explain the formation of these, Mr. Durell assumes that the water is super-saturated with dissolved air and that there is a certain amount of "occluded" air on and in the surface of the particle, and that these combine to form bubbles. That this occluded air may be present is certaiidy pos.sible, but that it would lie lilieratcd with sufficient rapidity to float the particles does not seem probable. That the water in a ^[. S. type of machine is supersaturated with air is also probable. Imt I cannot see how the w:iter in a Callow or other pneumatic machine can become greatly super-.saturated l)y the introduction of air through a coarsely porous medium such as canvas twill. The idea of super-saturating the water with air is not new. As early as 1007 D. 11. Norris patenterl this process. (('. S. patents No. 864.856 and 873,586.) Mr. Ncrris saturated water with air at a prcs.sure of .several atmospheres, and introduced it into an open tank at normal pressure, where the exces.s air formed what he called '"inflnitely small nascent bubbles of gas" which were suppos-d to float the sulphide particles. So far as I know, this idea has never been put into successful operation. As to :\Ir. Durell 's statement that the dissolved and occluded air are indispensable: if it is true, previous boiling of the pulp, which would drive out all of the dissolved and some of the occluded air. should interfere considerably with flotation, especially in a i)neuniatic macliine. I have seen this done in the laboratory of the General Engineering Company. The subsequent flotation took place with pv.M .M,. tl.„ o„. L-u:;i;i:css viicii inc siiniG ore was floated without boiling of the pulp. Furthermore it has been my oliservation. that when a carbonate ore is treated with soluble i- 188 Tin; :■ i.d'r \Ti(i\ I'UdCF.sr siilpliiW.'s Inr 111,, i.iirjms.. ,,r f(,riiiini; nn artilirial liliri m| miI|)1ii.I- on Ilie .siirl'acr of the luin.Tal parti. ■|,s. niiicli hrttci' ivsiiUs aiv obtain. m1 wjirn a small aiiionnt of alkali is addiMl to tiif pulp to iVMiov anv ira.Ts of 1I,S ^ras. This can also !,.• ac.-oniplisii.M| hy the nsr of SO,, uhirl, ivads with tlir \\ S t,, form sulphur anil ll_,(). ami (liM's not h-avc- m alkaline pulp. Were .Mr. Dmi'll's liypolhcsis truo. this ^ras sliouM l.c JMHriirial rather than .Irtriuicntal, ami It wmihl serm ijiat the f/i^m-ral rtVrci ,.f arlitirial sulphidinir woiihi lir tn r.'ilucf the amount of ,,c,-lml,il air rather Ihan im-reas,. It, as snme of it Would undoiilitedly he displaced hv II_,S which would latei- he I'cniovecl. I cannot ajrree with Mr. Durell's statement that floatable particles "ill not attach them.selvos to previously formed air huhhles. I nnde).. stand that in the suit of the .Minerals Separation. Ltd,, r. .Miami <'oi>per Co.. hear.l at Wilmiiifrton .May lltl.-). the plaintitT i)r...sented *" ""• *'"!"■< ;i nioviiii,' picturi' of an e.\|)eiiment in which it was shown under Just what condiilons the j. article would attach it.self to th.. hulihle. Aside from that, it is not a far-fetched assum|.tion that the air huhhles in an oil-emulsion iiave mantles of oil. Their property of frothiiif,' would so indicate, and. in that case, the surface films of water surronndiiiL' them would not ditVer materially from the films surrouiiiliri',' drops of oil siispemled in water. That such ilrops of "•' '••!" '■""•■'•I I'Mtahh- particles out of an ore can -■asily he proved hy shakni",' oil with a mixture of {ridena and sand susp(>iided in water. When the oil has collected, the dro])s will he .seen to l)e covered with the Efalena. If we imatrinc the centres of these drojis to he filled with air instead of oil. we have conditions whicii miu'lit easily hold in an ai-tual flotation machine. On the whole. Mr. niirell's hypothesis does not sci'in to conform with actual tiotation i)ra<'tice. There are other theories tliat explain tifitation in hetfi'r conformity with known scientific facts. T. J. Hoover, for instance, in his 1 k 'Concent rat intr Ores hy Klofation." presents a eonsistent theorv. and J. >r. Callow i)resented a paper to the rtah Section of the .American Institute of .Minin}^ Engineers 111 which were .s(-f out some theories has.'d ,,n experimental work done at the M,.llou fnstitute and at the local station of the V. S. Bureau of .Mines. This paper* will undouht.dly he piihlishod soon in the transaetions of the Institute. .T\MFS .\. BloCK. Sail i,ake fiM-li iiuulf hy .Mr. \V. A. .Scott, comusi'l tor dt'lViidaiit in tlic casf of Minerals Separation. Limited, r. .Miami ('oii|)er Compaii.v. We follow this imu with leiii,'thy (jiiotatioiis from ihe sju'eehes of Mesvsrs.-- Henry 1). Wil- liams and \V. Houston Keiiyon, of eoun.si 1 for the eom|)lainant. In the lirst e.xeerpt .Mr. Williams (liseiis.s«'s the article l.y the three students at the University of California, as piildished in the eolhsie iii'i'.'ii/.ine. Tin Califoniui Jaurnul af T, riniul, ,,)!/. The major jxirtion of that article appeared in our issue of July ;jl. UHi), to which the leader is referred* in order to follow the lawyer's remarks. In the second and third excerpts Mr. Keiiyon discusses .some of the ])liysics of the flotation process. Of course, the reader must remember that this exposition of the suh.ject, like that of Mr. Scott, is not to he taken as a seientilic thesis: it is essentially an < .r pnrU e.x|ilanatiou. hut even as such it is e.xtremely interesting to metallurgists. The first pateni in suit to which reference is made, is No. M.!.'),120.— Hmrdu. | Mk. Williams: The California Juurnal of Tiduiologn is evidence of the interest that the metallurpical world took in the Elmore process. The title is 'Experiments (ii the Elmore I'rocess of Oil Concentration.' The conclusion is: "The work aliove outlined suggests niany lin.'s of furtlier investi- gation, and as these ■ ome to be worked out, the process will become more valual)le and of more general application." What proces.s? The Elmore process. Fn l!tO:i, the Elmore process was a hope of the metallurgical world. Incidentally, the students discovered something else, and, for the first time, gave to the world the foam effect. Full (iisch)surc as to a mode of operation which would produce an oil foauL they, for the first time in the history of metallurgy, gave to the world. That was an incident of their careful invi'stigation, but tlie arti.de itself is on the Elmore proces.s. and it says that the Elmore proces.s was then a hope of the metallurgical world. TiiK Coi-RT : Mr. Williams, if there was a disclosure of the proces,s, filthough a misnomer, what would be the effect of that disclosure? Mr. AVii.i I \ai'< : Tl'e tiHine. oliviouslv h.r.:^ •.•.rih'.-.-.cr i.-. .1.. -.;-:!'. [t The CoiRT: No. •Sep page 102 of this honk. 190 TIIK ri.oTATluN l'|i(K'h> .Mii, Williams: I \vj,s piirlifularly dim'tinf? .„y attention to the tac't tliat .Mr. Sh.rulan look tlios,. last tliriM- lines as something whidi was .Imcte,! soKly and wiiolly to tl,at small part of this artirlc which dials with the foam i^tfeet. Till-: ('(PiHT: Oh, I luiderstand. -Mh. Williams : And 1 wits i.ierely ])ointiiifr to the fact that those lines n.usl have referred to this Klmore proee.ss as a hope of the iiiitallurj^ieal world. The foam etTeet here dis.-losed. uhieh is reeommeiHled as employ- nit' f<.;i',; of oil~it hei.if,' eh-arly shown that nothing else is worth aiiythnii?— 8.l»',t of oil and .salt solution, an ore eontaining lifjht flaky minerals, .siieh as molylnlenite ; and another ,)ne of the same kind is frraphite, and 1 do not know any others— <'ertainly not copper, cer- tainly not zinc, (ialena and hlende are not flaky. (;alena is almost '•ulMcal ni its fiacture. They call attention to the study of the frac- ture of minerals. They worked out this foam effect, which they give to the world, with the recommendation that 8.!)',;. of oil he used, as something which may i)ossihly he useful with light flakv minerals, and that became a part of the constructive knowledge of the world in November 1903. It is remarkable that it was buried and lost, and that it took three years of litigation to unearth it. That is quite remarkable, especially that It should have been ))uried and lo.st in the I'niversity of Cali- fornia, whicii is in the heart or the centre of the important mining interests on the Pacific Coa.st, and in the Great West. Hut that is all there is there, and the most significant thing about It IS that It tells the investigator: We have tried 2.1^,', and the i-esull is hopeless. We have tried 5.:i';; , an.l the result is almost as ba.l. Hut we have tried S.H'^ and there is some hojte in that. Now, procVed ■ investigate. Hut very ovidentl.v. nobody proceeded and investigated. There is iK.t any practical art, unless it be Elmore. There was not anv mill that made any use of any of these patents that have been referred to. Ilaynes lightly touched upon : Everson. the foundation of the de- fen.lant's ca.se— why these very students in this article tell the exact truth about Everson. I am sorry they di.l not write more, because th..y would have ])een impartial, and they would have possibly given us a fair, iinbia.sed inti>rpretation of the patent. •Tn I88fi Carrie J. Everson of Chicago* contribute.! the idea that •In tier first patent. No. :U!),1.17. she is described as "of ChlcaRo, Illinois," Imt in No. 471,174 she is said to be "of Denver, Colorado."— Editor. AIU-KKOTII ll.uTATKiN- 11(1 lliv niiiciiitiatioii w;is iiuk-d hy tlic pn'sciicf »( an ac-id solution, and [lalcntt'd tile same." That is just e.xattly what Carrie Kverson did eontrihute. It is an exaet statement, and tliat is preceded i)y reference to anotlier pat.'iit, which the defendant has not seen tit to refer to, although it iuw ti^fiired in some other litii(ation— tlie patent of Tunhrid^'e, erroneou.sly liere spelled •Turni.ri■ le- vaney. and the defendant has not relied ui)on it, and it is, as your Honor will note, later than Ilaynes. As (> matter of fact, the reference to this pat<'nt would indicate a study of the Everson patent, because th.' Kverson patent di.sclaims the Tunhridge patent. It does so with "t ol soin.th.n,. w„.,.|, „til,....l ,.i| ],. „„. ,.,.,„.,.n,rat.on „| ,„vs -^ i"^; ".'.v nn, ,.„n,.,.,.n,.,l particularly will, ,„..tl,„.|s. l,ut .h.v uviv '-kin,' at It a ways Iroin that viewpoint: that is whv th..v r".!'..,- to lMnl„-„|p.. ami why ,lu,v ,■,,,., ,„ k,.,,,.,,,. ,,„ „„.,.„ .; ,,,,^- ''.• M,.„.s,.on n,..,nin. tln.ni.h h.iv that th.- Kvet.on pat-nt, wlu,-. -> say has proved ot" no pra-ti.al valu,.. makes anv su.,es,ion of tl'.tation. Kverson merely eontrihute,! the U.S. of a,-i.r Mk.AMu.-ms: I'no.. to ,h,. invention of ,|„. ,i,.st pa,..nt in suit •""' '""'^"'« ""'•^' '" "'"'f ""■" 'li'l. -.■ lin.i that wet-eon..entration Pn,e..s.ses were the solution of the oro-eo„ee„tration prohlem Thev ^|■.■^.■ he ,>roees.s<.s that have heen .le.serihe.l here. an,l that I nee.l not ' e..r,he ajrain: p,-oe,.ss..s that depend „pon gravity and shaking and > -t.on of ,„H.|y ,.n>„nd ore suspended n, movin. water, the sepai^Uion .l.1..-nd,n,. upon the ditTerenee in sinkin.-power of the metal an.i the extent stdl. but that are hein^,. superseded in the la.st two or three >ears to an a-ston,shinir decree hy the processes of the patents in suit Ao.n, these wet-.-on-^entration proees.ses advantage wa.s taken of >e faet that the metal had a higher speeiHc gravity in the avei. han the ganfrue. an.l the laws of nature were followed. The heavier .Inn. wa.s a l.,wed t.. settle, and eireumstanees and conditions were .s> '•ontrol ed that ,t would have a chance to settle away while the .an,, :>.. .1 -.0 le t suspend..!. The ,an.ue would he floated in n.ul-hulk "1 the hqui.l. and up an.l down and all aroun.l, and finally floated off oviT a dam. Hut all wet-concentration p,oces.ses-and the machinery for car n.ngr them out ha.s exercise.l the ingenuity of inventors for thirty f.!ctV; Ir''"'""'™""''*'"" ^""'''^'' ''''" "^'''^•''^ '^'^ «'i>"^' «"{ uravity. Tlicy will slay up wiili tli,' hhuhw'. 'I'li.'y will" tl,,al <>t\ with llic f,MiiK'n.'. Th.'y will run to wast,-. And hm.".' wv liii\c tli.'Sf tailings in Australia and Iutc, of millions of tons, wli.iv tlu- .slimed metal, the linest of the iiK.ial, has all run oir, heeaiise it eould not he recovered. With siieli eoii(..'ntratioii i)ro(.es.ses the hest that eoiild he (hiiie was from »i() to 7(»';<' recovery. Prof. Fulton (?ave TO", as the outside limit— GO or l()';i of the sulphide m,.tal in the ori^'inal ore. And yet men persisted in using that pro(.ess. Klmore. atmut the opening of this century, ahout 1900— his jiat eiits were a y.'ar or two earlier— ..aiiie in with his process to reverse the laws of nature. Instead of Uridine; th.- heavier" tiling at the Ixit- tom, Klmore said: "I will carry it to the top." A?nin a process nseies.s on sliim.. Again a proc(..ss rcjuiring coarse grinding as liefore. The concentrate at the top now instead of at the iM.ttom. The theory of operation was an oil lake. I like that word 'lak.'. ■ It is used hy the California Jounml student.'r— an oil lake. Air ..iitrainment was fatal. Ingenuity was ex..rcised to so mix the oil lake and the ore as not to entrap air. Oil emulsion was fatal. The amount of oil we know was 100 to .'{OO'-;. on the ore. And yet men did that thing. .Men paid that price, and the loss on every 100 It', of oil was n or 10 Ih. at each cycle. The other 90 lb. had to be taken out. and preserved, and ii.sed over again. And Catterinole. The very men who afterward made the invention of the lirst patent in suit spent two years and a half developing that (Jattermole process, a really beautiful id.^a. the lirst process addns-sed to the .slime problem. Said Catterinole to himself: "Now, if I can have fine grinding of the gangue and coarse grinding of the metal. I can separate the metal out by its dropping and by the gangue floating." For right there is an interesting priri" .'iple of physics. When a particle is floating in wat..r. its tendency to sink is determined partly by its weight. The weight tends to carry it .lown if it is heavier than water. The surface of the particle tends to resist that, tends to keep it up. If the surface is greater, in respect to the weight, it will not go down so fast. If the weight is greater in respect to the surface, it will go down faster. Now, if you imagine a little culie of metal suspended in water, .ti!;! imrsir-r...-! -.f= !-:-...-..-. .i: sions doubled in all directions, the surface win Iiave been'squareil. and that is the thing which resists dropping, while the weight will 194 TIIK KI.OTATK'N PKOCF.S Jav.. beeii cube.!. Tl.e weight l.as inereasod la.st.r than tl,. .suMa,.*- llH-iv ore tlmt dounl..,! ,uh. will si„k faster throut;!, wat.r. That aw of the square as to the surface, resistiup sinking, and the cube as to the weight corn,,elli.,g sinking, is the thing that niak.s big pain.Ks drop more u. aceordanee with their true speeifie gravitv, but fine par- leles hke slunes refuse to obey the hiws of specific gravity, and eon- n.ue to float and not sinlc. whether they be mineral or whether thev be metal. As Dr. Liebmann illustrated on the sta.id. if the rain came down in a shaft it woul.l kiU us all. When the «ime amount of rai., is t)roKen into small drops, it does not kill us. Whv? Heeausc the stir- faee has been so enormously inereas.'d with respect to tiie wei-lit or Vice versa the weight diminished with respect to the surface So the resisting surface makes those drops co.ne down, not like bullets l,ut gently^ And going a step further, when the particles are smaller s dl, they will not com ,iwn at all. They will float like the summer c-loud m the sky. Their specific^ gra ity is ju.st as great as it ever was with respect to the air. but they are .so small tiiat fhev are floated The Court: Ts if because they are ... small, or is it because of their form? Mr. Kkxyon: Their form would have a tendency to be spherical in all cases, but it is a function of their size. TiiK Coi,RT: I suppose if you dropped a n,.,.dle into water and kept It point downward, it would go down fiust. Mr. Kenyon: Yes. it would go right down. Drop it , sidewi.se so tliat you have multipli,.! the surface wifhotit changing the weight and It will stay right fliere. No«-. Caffermole conceived this brilliant idea: If J can onlv make my gangue particles fine, they will stay up there indefinitely If I ••an only make my m.'tal parti.-les big. they will drop faster He knew lie could not do that in grinding. Let the invcnt<,r of the future if he be here present, fake this for a cue: A grinding machine that" at the same time will grind the gangue fine and the metal coarse will rcvolufioiu/e all these pro,-es.ses. raffermole knew that could not be done ,n grinding, so he said: "I will grind it all fine, and then bv the ghung effect of oil. particle to particle, oil which g„es to metal •ind does not go to gangue. I will roll and work my metal particles i„tn big metal particles, whereas the gangue will remain as tin., as if w,s ground; and then when T have done that, my big metal particles mv grariules. my spherules, will drop and the gangue will go up." ■ :--r.: r. ;•„-. i:;;- •, .i i I rriii, ,ir iu.a, rtiKi men propo.sed to do that thing. AIR-KKOTII KIAJTATK^N — II Iff.') and these plaintifT.s, and the world would have been concentrating their ore by that process today in preference ta all others, probabh" but tliHt the invention of the first patent in suit was made. The Catterniole idea of operation was by oil adhesiveness and \yjyX*iJ-***J ^hCkLt H^4 FlO. 40. DRAWING ACIOMPANVING .K. E. CATTKRMOI.e'.S PATENT, >(., 777.27.;. „k PECEMDEB 13, 1904. nii.xing. Air entrainnient was a trouble. Flotation scum was a loss Two to five per cent of oil on the ore (4 to 10% on the metal; it was a rich 50% metal ore) was the amount, and if the effects were dimin- ishin^. then thev iiii^rensi'.-l ^Jitrl-.tlv i\... ......... v. i ..i? „:: • "" ■~'-5--**J' i;-'' ;4:i':<;tw*r »"»r Oil. v^iikifcCilis Printed Record, p. 212. Q. 4.3, 44.) 196 ■I'JIE KI.OTATION I'KOCKSS riifivuj,,,,. a iv.-,.s.s wiis taken until tu„ oVlo^k i..ni. .siiine dav. liiK CoiKT: .Mr. Kenyon. I was wry nuirli interested in the ivniark you were n.akin^' h,.f,.re recess on tlie matter (,f tlie dittVrenee iH'tween bi!,' parlirhs and little jmrtieles, in the stren^.h of their powr to overeoine ivsi.stanre. Now. entirely (uside rroin surlaee ten- sion as sueh, and 1 mean that sort of tension to enable very minute partieles, although iiaving a trreater sjieeifie gravilv than other par- ticles, to float on the surfaee. Aside from that, and ashie from the • .IS.' in which the mineral particles iiavin- j^reater speeifi,; gravity are atUiehcd to any medium of buoyant eharaeter which tends to sup- port them, the.se small parthdes, if once j.laccd beneath the surface ot the water, having great.'r sjiecifie gravity, of eoui-se, would sink -Mii. 1vi:.nv,.n: Y.'s, ami No. The ....ar.sest will sink at once. The finest ot them wouhl ultimately sink, but the finest of them wouhl take so long to .sink that it is im,.raeticabl,. to separate them or do anvthi,..' with them by sinking, and that was the slimes prolilem in all" thcie Mietallurgieal operati.ms. They would float there. Thev would float 111 the liquid. When y.m get down to a certain ultimate i.,>int of fineness, vhether it i,e metal or gangue. it will float in the water under- neath the surface. Tin: ('(.iKT: rnderneath the surface? -Ml:. Kk.wo.n : I'liderneath the surface. Till-; CoiuT: Hut still they wouhl gradually sink? Mr. Kkxyox : After a long, long time. TiiK Cu-KT: [ would like to underslan.l you. Of course, we all know that if we could conceiv.. a{ a perfect vacuum, both a hiilh.f and a feather will go down together. Mu. Ki:.NV„N : Culcr the law of tiieir si.ecitic gravity ab.solutelv. liiK Coi-RT: When you .•oiiie. how.'ver. to a resisting medium (I do not care whether it is air or water, then you have a different propusilion. and there y.ai have a resistance which has to be over- '•"inc. and as you proc^cl arithmetically the resistanc inciva.ses geo- metrically, I believe. Ts that right? -Mh KiNVdn- : Vrs TiiK CoiKT: My .piesti.m is whether these i)arlic|es would limilly sink. 1 want to get the theory if I can. Asi.le from the .surface tension, il you once get those partieles un.lern,>ath the surface oi the water, not attached to any bubbl,. or any substance which ha a less specitic gravity than water, will they not sink, although at a greativ diminished rate? Ar.. T.' >r.i .,. . . -I".. :-.r.r ivr, : ; ;;; y v.iii UK mmiciv sink, aitiiougil tiieiv IliaV be ii^^ AIK-FROTH FLOTATION- lo; what they call a colloidal condition, which has hccn somc-.vhat dis- cussed here— clays arc very colloidal, and have a tendency to keep them in suspension i)erhaps for days before they would sink. Even they will, as I understand it, ultimately sink. TiiK ('(jiKT: Ultimately? Mr. Kknvox : The least little jar or agitation will send them ri^'ht lip ag.tm. The whole slime problem an''. t IS, Its power to rais,. mineral particles that arc also caught ? s„ ,1 ,„ the 0,1- oan. processes of the prior art) is not securcl unle:s '"■ ;'-"" '" -.l ..s surticient and the character of oil suitahle to so MH-hanu-aliy cnhraee and entrap ho,h air and mineral. That is the oil iinist be vjseous. Air has a powerful affinity for clean, n.etallic, sulphi.ie surfaces ns aftunty . defeated for all practical ore concentition purpl^!^ en 1 when the nnneral surfaces are coated with so nu.ch 'l as to exh h,t ,hc physical properties of oil as such, such as adhesion ,0 other sundar oded nuneral surfaces, as in the Catterm.le proces.s or < herence to an od lake or to an oil foam mass and resuUant huoy- . '- rtotat.on, as m the Elmore process, the CaHf.rnu, Journal aocess, and so orth. Hut when the filn. of oil on the metallic sur- it'ZTT^ f "r' ^'' "'"" "^' '' °'' *" "- - -"P'--i) sii V 'i ""■ r V '' "" '""■^'■•^ "-lefeated; it seen.s to be 1-situeh „,crease,l (why. we do not know) so that for all praeti..al oro concentration purposes in the nnll the attachment will perJ J "".1 out 01 t],e pulp, and will survive any a.nount of e.xces,s -...itatio or of excels aeration in the pulp. 'i^irauon Air bubbles have vastly ,M-eater lifting power for metal particles t an oil .lobules have, and especially the sort of air bubbles that are pioduc^ed, either by a,^itation or by aeration. i„ water modified bv the reagents ot the patents in suit. • Air bubbles in unmoditied water, however produced, pro.re.ssivelv an.l rapid y codesce. and with explosive violence, which tends to ex- pl. in the fact that such air bubbles, namely i„ unmo.lif.ed water u Ml not practically concentrate ore. suitHi'vI"'!''''"'.'" '",'' :"""'"^ '•'■ ''"■ ''''""'''' °f the patents in suit ha^e an enhanced .selectnv affinity for metal over jran^e (whv -e do not know), ami a persistence of l.fe as bubbles i„ the pulp and a P--tence of attachment to contacting metal particles in':;;! '">' -: the pulp sufl.cent (but why. again, we do not know) to pcnn, ,n pnictice of ready separation and removal, and to resu flieieh\ in cfTective ore construction. Tin: CorHT: You say "AVhy. we do not know." Is there anv theory on tliat subject? • -Mr. KK.NYf)N : We have presented no theory. The Court: You have no theory? >rFt. Kexyhn. We have no theory. Dr. Sadtler says variation AIR-FlioTII II.OTATION-- l!)l) ,in not t ""T" '"'""" ''"■ "''-'—"' '"'t I'-v ' .io not know. I do iot know how variation of surla.-,. tension can enhance sc-lective . ftnit^y or how it can cxphiin persistence of life as bubbles in an,] "Ut of the pulp or how .t can explain persistence of attachment to -n acting >nctal par,i,-les in and out of tl.e pulp, to such a degree that practical ore concentration in a mill is an ac oniplished fact Whatever the explanation of the phenomena invo.ved, it is clear that the operation proceeds by cc:.tact of air and metal in a freelv flowing pulp under circumst.n.ces conditione 1 .v tl- presenc Jf n.n.H'11*."'""' ' ^''" '"•■ ""■ '■""""•' ^'''''''' ^''"' '''' «'"' "'^ "li-H^ral J'<*1 IJi. its . Ml«. Kkwox: 1,1 thf pulj), T,iE (V.rRT: Xow if the mineral particle has a rilm of oil. no atter how hin. how is there any actual physical contact between the an- .nid that ])article? Mp_ Kexvox: The mystery of the thing is that when the oil fil.n ot the attenuated character that is produced with one-tenth of , ot od to the ore. when that film is present on the metal particle t - au-part„.|e has .,n enhanced appetite for it. seeks it with iiLeased aA.dit.v. instead of with diminished or defeated aviditv such as a ttncker him will produce. Thf CocRT: And it .seeks it through that very thin film" that hel, s'''"'^'^ ■''''''' '^ """""^'' ^'^'^ '■'■'•■ *''■" ^^'"' «« •* ^^•"'•''~ Tmk CorRi : Not through the actual co.tact. but through the film l,eing so very attenuated, it seeks the metal particle, and the n.'erpoMt.on ot the film, far from lessening the s.^ctive a..tion of llie air tor the metal, enhances it— is that n>'ht' Mn. Kexvox: Yes. that is right, and Dr. Sadtler on the stand uggos e. an Idea tha^ may help a little. He said that an attenua "''"•'t that kind might po.sibly be concived of as smoothing roughness ot the surface of .Lavage of the .sulphide particles Mr. A\ii,li.\ms: That was Dr. Liebmann. AFk, Kexyox : Dr. Liebmann ? Tiif: Court : Increasing the eflfect? Vnf n,^T'''!r I"7<'«''*i"P the attachment or appetite of the a,r bubble for that surface .so smoothed. \1t> ^v, y iV.iii suggested it. Mr. Kexvon: Yes. Dr. Liebmann also suggested that idea: and 200 ■l.Ih; Kl.lir ATION l'K(ICE;sb Mr. l)osri:liilcli, MS I i-fiiiciiiliiT. siiiii tliiit wlicii tlirsi' |mrtli-lcs IiikI roti^li siirfai-fs the iiir Imhlilr would not liolil tliciii. Tt is the siiiootli siirt'aci' that tlif air hiilililf j;t'ts its ^rip on. Now. tliis iiiicroscopn; tiliii of oil may lill up inii'roscopic cavities. iiia\ l)ri(it;i' over niii-ro- scopic rou<;liiit'ss«'s. may make smooth wiiat was hi't'orc I'ouijh. aiul ill tluit way cuhauci' tiio avidity ol' tho aii' pai'titdc for it, and the •rrip of the air particle u])oii it; liut I present that uith ditlideiice. That is a matter' of speculation. T.y9 Fk;. 41. TilK (JAHHKTi SlIXKTl. KFm( Kl) lACSIMlI.K Cll- DRAWING IN K. B. GAnnKTT's PATKNT No. H l.:U.'. .lAMARV G. 1S91. UK-rHOTlI Kr,OT\TI(l.\- 201 TllK ('(iritT: V(i\i have tlic uvidriiec on liolli sides lor that, sii 1 dii not siipposf coiiiisi'l on cither si(h' will contest it. -Mh. Kknvmn: Tliat is .so. hut witii all rcsjicet to hoth witnesses. I present till' siitrjicsiion with dilVidencc, Hut now let nic state atrain what arc tin' clear essentials I'roni tile point of view of operation, whatever the explanation of piienon.ena. Whatever the explanation of the plienomena involved, it is clear tiiat the operation proceeds liy the contact of air and metal in a freely flowing' P"lp under circumstances conditioned by the presence of the rcatrents of the patents in suit, and ojjiiortunity of flotation after contaet. Vou have trot to l)rintr your 1)ul)hlo and your nietal particle into contact in this freely flowinjr pulp, and under circiun- staiiecs conditioned by the i)ri'sence of the rea|;eiits of the i)atents in suit. l-!ut to have liroufrht them into contact — that is not onoujrh. There must he another factor, namely, opportunity of Hotatiou after contact, .so that you may separate — flotation uj) in the pulp and throusrh (he surface of the pulp — so that you may practically sc])arate them. Tn:; Corirr: 'i'hose iirt> essentials in the flotation. Mi;. Kknyon: Those are the sine qua nornt, and those are the only sim: qua lums if we have presented the projM'r theory of operation. And as to apparatus, it is clear, loo. that apparatus for erticicney bringring about iii a freely flowing pulp the contact of air and metal under the conditions stated, and for permittinre inactically imconcentratable in the prior art. except perhaps by Cattermole — I say 'perhaps' because Cattermolc never reached the mill. On the threshold of the mill the life of the (^attermolc process was cut otT by this prreater child of the brains of Sulman. i'icard. and Uallot. It has been shown not oidy that the fine and slime that were practically unconcentratable in the prior art (except perhaps by rattermole can be succepsftilly concentrated by the proces.ses in suit, but also that the presence of such fine and slime in the pulp actually assists the concentration of the ore. and is indeed almost cs,scntial to practical success; so much so thai the art of grinding has b.'cn revolutionized where the processes in suit are employed and line Kriniiing lias become itie rule, wiiere before it would have been the ruin, of the mill. The history of what happened in the practical art before the n 'J(I2 ■rrii: ki.utation i'imci;: iiivfiitidiis 111 suit wfiT iiiadc. ami of wliat lui.s liapju'iir,! in th,- prartiral art Niiiic tl.at time, shows tiiat wliilo ways and incaiis of I'l-infjin-; alioiit imita -t of air ami metal in the pulp and of jjcrmittiiif; or iLssistinj.' Hotatioii after eoiil:iet may he wiilely varied, the success ' '■ the ])r;ii'ess is sharply eomlitioned witliiii relatively narrow limits ill Ihe matter of the f|iiantity of reaffeiit employed, when that reag;eiit is the oil of the tirst jialeiit. Ksperially is this true and crucial in the ease fif the lirst patent in suit, since it has heeii lonped contact of the material with cvanide. extendiiiir in some case.'; to over n iii.infV. In the case of eoneentrate produeed by flotation, the minerals eomposinof the product are substantially the same as those obtained by rrravity concentration, consistinpr of the sulphides and double i ^ a 1a O O r-.' o o o o c O OJ* « ." rt CO M CO CO l.O 4.0 OC OC H -o K O < 4 i s o ♦J d 2: ~ o 1 •a ^ 2: a, c: c eg t c4 o o 6 «J c C u (_ c 1 *-> J ^ r s = C L. * ' « OJ "S o 5 a. Oh fi H 55 ^■ I.'; -^ t- 30 ao6 nil. HiirMiiiN I'lKicEM 'I'lii' lif.st t.'sls wriT iiiaili' uilli ihr olijiMt (it' ilfliTiniiiiii^' wljcthrr llii>s iiiiilfrial cimiM Im' trciilcd a henclit whatever. The fact that hroino- cyanide has a marked itTcct on the extraction sujrjrests that a portion of the u'olil may he |, resent as a tcllurid.'. This conclusion is supported hy experiments made liy direct treatment of the orifrinal oro, without concentration; these tests showed that a certain i)ro|)ortion of the >-'"''' '^ i'l'" ssihlc to cyanide even after very line ffrindiiif,' and prolonged contact. (See Tahle XI.) As these results did nut appear cncourajrinji for any system of raw treatment, attention wjis next turned to roastiiip. It was soon found that roa.stinj; within certain limits of temperature converted a consideralile part of tlie copper into sulphate, which could be leached with water, tofjether with some .sulphate of iron, leaving' the lesicliie ill a favoratile conditir»n foe \vanide treatment. Preliminary acid wasli of the roa.stcd material was also tried; thi.s would have the adv.-iiitair.' of dissolvini: a further (piantity of copper that mi-rht have hecome converted into oxide in the roa.stiiipr, hut the results show that the benefit obtained would not warrant tli(> additional cost. Another test was made in which the concentrate was cyanided raw 1" forc' roastinj,' aii.l acid-wa.shintr, and re-eyanided after the wasliitijr tills also showed no advaiitaire either in extraction or cy.-inide eoii- sumption over direct roast ins:, water- wash, and cyanide. In all Ci-scs the roasted material was ajritatd with cyanide, using a dilution of ;^;1. Th.' results obtained by tiie.s<> three methods are shown in the followiiitr table. fXo. 11.^ In Test No. 2 the aeiil-wnshinff was made with 1^ II.SO,. usinp approximately" n tons of wnsli nor tnii of enneenir.Tte tre.-.f^j.l T'..--?.-.-.-. agitation with cyanide, the pulp was re-ground in a model tube-mill with glass marbles. CYAMDt TKKATMKNT OK KU)T.\T|UN (DNC K.NTKATi; -'07 ;i7! p i'i i . 3« It T ' 5 -ii "«.. P (0 3 ■ D O s > a 1 ^- « i^ S J « CI -! SI ^ 3 ■' - -B ° 115 CI '=; C 3'-! 1 ^ QC 3 = o c, 8 ■♦ !i -r 1i 185 >< 3 < a < 3 . -r •r -r > , . Cl CI CI ^ ff; OS m Sf ! E c p*^ X X X a 5C i^ ^"^ ^ « i-i — . a> o 2 a CT1 j: O rt •o It R ■a cd o . CO o •j"p - h ^ o ai c? s i'Ts E:3 =^ r o> s:^ *S "n tn 1 " I/! CO ^ _-_■ lo irt o oi . bi: TZ » CI ci ^ < > M bH c i^ d o o g .5 = ^5 a, tM N — • t , Oxidi Oxidi Cyan h- 9-^"" - o o 5 d g Z i?; z Z a M ffl K H 'H c M * H f- H 'til ii 2(tS ■IHK 1-1.0TATI().\ I'KOCES.S In Test No. .'} tlie preliiiiiiiary raw treatiru'iit was made witli 0.1% KCN iisiug a dilution of 12:1, for two days; the extraction of gold was 12%. Aeid tnatiiient was made with 1% ILSO^, dilution 1:1, agitated IS liours, and then leaehcd with water before eyanidiug. Roasted and washed concentrate agitated with cyanide lor i days. Test No. 1 on Tal)le II indicates tiiat tlie flotation concentrate from the San Sebastian ore may be successfully treat. 'd by a siini)l(' process of roasting, water-washing, and cyaiiiding. This conclusion was confirmed by numerous experiments on a large scale in which the material was roasted in a haiul-reverbcratory furnace, and the roasted product trea'rd by agitation in tanks with mechanical stirrers, adding water, .^'ttling. and decanting until the bulk o the copper and iron salts was removed, finally collecting the mat.'rial on a vacuum-filter ami wa.shing on the filter to retmive the last traces of soluble siilts. The washed concentrate was then re-pulped with lime and cyanide solution in ai agitation-tank, and treatment continued in the ordinary way. Tlie results of the bottle tests were fully confirmed. Attempts to treat the material by percolation were not successful. Owing to the fine grinding of the ore previous to flotation, the roa.sted material showed a tendency to slime; percolation took j)lace slowly and irregularly, through chainiels formed in the ma.ss. .so that the extraction by this means was always imperfect. In the tests made in the larsre muffle the oxidation was somewhat more effective, but a rather longer time was re(,iiire(i to reach tiie temperature a- whii'h roasting began. Tempi ratiire was approxi- mately determini'd by Seger cones. On examining the details of Table III. it will be apparent tiiat the most favorjible re.sults were obtained when roa.sting was carried out at a low temperature; under these conditions a maxinnun amount of <-opper was extracted by water-washing, an.' the hitrhest extraction of gold obtain.'d with a niiniitium cyanide consumption, Tn this ore the silver is neprlifrible. but it is signifi<-ant that tiie silver cxtrMition on the roasted material is poor in all eases. This condition will be noted in most cases wh(>re attempts have been made to tre;it silver ores by cyatiide after an oxidizing roast. With these results as a guide, tests were made on a larger seale on fhe same material, roasted by band in an oil-fired reverberatoi-y I'urnaee, .\ ehaT'Cre of about 400 11) w;is d.rjed slow'v in ;; ';;i!e.:-.!: drier, and charged into the furnace: the temperature was frradnall\ J CYAMDK THKATMK.NT OF FLOTATION CONCKNTKATK 20!) " c a """ a ce •o ■o Oi a 2 "bj. u < B, u S u Z = O «-> U 73 :- ti! % ■a vC M :d •a . ^ u o o iJ o H •a = 71 a o taM •< oi r o 3 as ® "o H U) Q X J H PS 3 n E .. < H lie E- o 5£S O roasted was as Lime, % KCN. o to ^ ■ "^ ca a a o ^ 0. B o "= o H -< o a *" i « J) a, ca S < a S i: .E Ul o a a a 5 grams of c rge for cya shed conre strength m o a c3 <=- •= i* H -,0^0 5, 0. 13 '5 1 mI ■§ =" •- a '^ n ^ ,-a is Ts s S n 2l— l-l«Tf^l.-5'* lO t^ t- O t- a, o Q Ul ° o n ■s^- o j: J ^ r lo CI cTi o o a; ^ ^ » a: 00 c) . 2 vs> ■«" ■^ M t- O W CJ iM O t-t O CJ ^ - K It ^ OOOOOOOO'O mirsooc-joaeo^fos Gcc-ifo^cofocomevj t-OCGCOOOOOOOOOOOO o o o o o o o o o '-'d^O'. cctxt-t-oo r*^ Cs O (".^ (T^ fV o/^ i-^\ i-*-i j-*i ,-j- ,^« < »; tj O jj" flj to < c o dJ Occooocobooobooocoo c^ o o o o o o o o © 5 1.1 i>0 O C I ft u't I'- ^ ic 1:0 "^O oc ;d [- oc ,000000000 5^, CI a> (M CI ic 10 c: cft o) -_ o irt :o !X ^c c£: m in lo £"0 ^— (!;•— (Jj-- (JJ.— 1 OjQ; 1 = 2^2 t-l£J«tf£? o . c o mJMJw.Jt»jj 0) c H ^ ^ 10 «; I- oc cj 210 TIIK FLOTATION I'liOCKSS a X O T3 a; a, ?« 3 to o "O ooooooooo ■^ 2 ooo ^ ooooo > H o o LO .-H ,- t- 2 ^ *»< OS o o O t^ r^ c-i Tt" to ^ oc Ci ci a; ..-^ ^ t- ^ 1.-5 ri (7s -* O (M i-H (M -J- CC Cfi e-'a -*r o t- CD en 00 S -a _ ^, t- C) Oi 'J CI CI M a; ^ o Id M o O o o o o o o o d d o o o o o o o CI ^ ^ -.jj Lf: GO f-^ « lo 1^ CI ■s rt* ^ ^ csi ci in d M oi ci cc -*r rt i; rr CO C-l M rH W C^i CO M •*• c t o c 3 ^ rHCJC-Tt^OrO^^^O d >Nooi^ooooooooooait- ® n: O o d d d ' " " " ooo rs . ^ O i.*:; T 'x: -J c. rx; c: -nOcocococqcococococo ^, . IM ■* O C-l 1^ M MJ -J5 CI ^' ^^Notr-ooooffiooi -- — o -; d r^ r-' r-; r-; d r-: d if u yj c 2 ^ t^ Lrtt^ot^^j'jm^co M-cOi-IirJcjoiddt^ iTJ C-J c>j ,-. -J ri C^l CO CO o 'C CO i^ CI ac ^ c-j lA I- r- « 00 ■ 02 en sv as 2 S « "f -^ -f Ct OJ OJ i; -a O o § °. ■^. °. -: '^. ■=: <=>. 5 d 5 •-* li^ •*• 00 O Ci O 00 OOOr-tTH^^Or^O tc S .5 t£ g d — rt O K i_ I- -"3 t^ S =* - O tfl - 2 a, o i: O d CO to CO r-i CO t^ O r-. o o o o o d d d d d d d o d ■ ■ ■3 o ^ o 'jo cft o o J-; - K TFiK\l'.MKN T (IF KI.OTATIDN (l )N(K.\TKA1'K •_'ll raised till it approxiiiiutt'il tiuit obtained in tlu' iimffle-roasts. jirolialily alioul 550° C. After .'{i hours, the tiaiiie was turned off and the charge allowed ' cool in the t'urnaee over-night. The eoiieentrate roasted in this way. showed little or no tendency to sinter or form lumps, hut in suhstMiuent tests when tlie material was charged without previous drying, {)ortions of the concentrate agglomerated into com- paratively hard lum]>s, which contained a core of unroasted material, and which it was necessary to sift out and re-roa.st after grinding. Possibly in praeiice it would he advisable to j)ass the material, after lirying and before roasting, through a ball-mill or similar |)ulveri/er. A bottle-test made on a scale of 100 gm. on a sjimple of roasted concentrate from the above i'cverb(>ra1ory charge showed the following results: T.ABI.K IV Copiier extracted iier cent of raw concentrate: By water-wash 0,435 B.v cyanide 0.039 Total 0.47-1 Cyanide consumed |ier ton of washed concentrate 5.03 lb. Cyanide consumed per ton of raw concentrate 4.21 lb. Under cyanide treatment 3 days 1 ton raw concentrate ==0.837 ton washed. Gold. Silver. Oz. Oz. Assay of roasted concentrate 3.70 0.86 -Assay of washed concentrate 3.90 0.94 Assay of washed concentrate caNiiUittd on raw coiircMtraic 3.2ti 0.79 Tx)ss jier ton of raw concentrate 0.24 0.10 Residue assay on washed concentrate 0.05 O.tiO Residue assay calculated on raw concentrate 0.04 0.50 Kxtraction on loanted and wa-shed concentrate 9^.7 36.2 Kxtraction calculated on raw concentrate 9S.9 43.8 Recovery calculated on raw concentrate 92.0 32.6 The loss shown in this test seeiris to be mostly meciiani<'al. due to dust carried off while stirring the charge: it could probably lie much reduced by using a suitable roa.stt>r with revolving rabbles and a dust-chamber. AoiTATKiN Tests The following tests were made in small tanks fitted with wooden paddles. No. 1. Agitated with cold water, washed by settlement and decan- 212 TIIK HAVrATIOX I'KOCESiS -i S l*"- £ £ . £ .o £ £ O M 5^ CO O •■ 2 o c^ cj " : c : 2 o a V a, 2 S a 2; o g 3 2 •« S G i 13 I. g a, »* o •a I" '^' " 13 ■o Sec S c3 CD •'^ >i X -! O U 03 O - §2 c o 5 M a M - i: "^ "S M p, a O !3 *^ o 0) M <^ "o '^ -a O O DQ "O I 3 S rt < X ~ .5 o • c 2 H H . o » t- -. o in t^ CO •• ^ 00 00 CO o o 6 o i~ ■< ^ 1-1 QO io- " ' c e a < D c a ?; ■< c ^~' ■0 3 < n 0- £ s s z F; Im u tS m 5 < 1 1 if u a >- 03 II 0) 11 5 0; is a V rt c5 < L. ^ s c a t- OJ 0> ctj X to C' 3 c • rt C! M "■ a • c- & S ^ 2 ::* CD a a c3 t- t^ c A w .^ a Ci 'ol 3 is «-t r^ z. ^ n, . CI CO -^ Ol > N 00 00 CJ t- n; o o o o o •^ '^ CD o --: ■ O t~-* CO o* ^ cJ ^ ^ **■ la CO CO o :5 15 CO CO CO CO r c . ^ t o 6 ^ is 0000 ^5f ■^ T gt „■ -. ^ l-H r- CO 00 oi ci d ci Cl CI oi ro IS ST r- ca 30 CO O t^ Oi 2 k: ® ec •-• OS ci CO CO C-J CO rH *« ^ CI -J- i.o -^ T; cN r- t- 30 00 _ _ ^' c^ Ci o c ci c: Z, i J2 -c f! J3 is to s -2 Oj C CO i S a 3: ? nl c "O '*— r C U o CK «- g U ^- S 2 2 > ^ -a ?= w cU # 3 a> P 3 ■a o 5 a a o t: 'C !f a s X ■a O' 0) 73 ^ :3 o o o •e

s - ^ ^ M O ° S =• H Q • -= « I O — -Mi I.-. o - v: = .S 2 § ■n = (M ,_^ • c /: o c o c ^ o P o a < o t- u X 3 ■a 1 0/ c n CO d o 5 X a t- c o 1 jQ 3 o a o c rt OJ ji o ^ □ _, c a a; c a ■a a o C 01 1 u 5 0^ ■3 o G O I- SS tD ■a g S 2: P — *j ^ -J M o • H M 2 "^ '^^ CI ,, --H -: ^ o 00=;'-?': >= t" H >i ^ o^ O ^ "' c "-■ CI C) ^ .^ [ c:^ p,; o Ci ci ci „ in t' o o i« co . > d 'J !i? ':? f: t° in cj ^- ^ ci o O c CI CO CO ■* CI CO o •*-! OD H 'O ,j '■'5 -^ ci -•:) I o S --^ '•'? " -■ 000 CO «5 ^ en t- o t> CO -^ ■»)-■■<(-' t-^ 00 00 00 OS Ci [' 00 a; o 2: 7 'O ^ 0; u 0; < a e ca 5 S s r K M o o X: C3 0, * — 214 TIIK KI.OTATION I'KdCKS; I w e S b ^ 'O - o c — ' d X J5 1" X fl u ■f o si O ^ o c O d J= ? « i a = o ^• o<3?? > N ;£ Lj^ ir: tD t- ■00 00 1-^ a- — o o ^ CO '-' o 5 ^ 7i ■^ 'M — ^__ H ,J w ., irt CO t» ■f o S o o 00 r^ w o c Ci Ci OS O -H O > x: •a 3^ ;::l f ^ g < CQ a £ - t 5 a 03 t N ire - O o U 9 Cl Oi t- vO ■ • • C- r- ^9" M a =3 5 ca M »< 'O w CO QJ c •a 3 ^ .^ .2 S -o £ .a; 't- o i c o ^ Ta 3} QG ■a n so" O „ •a • 00 ° O _: •O _- ■ S g J n 5 ij o — S u 7^ c .-> .. 1" o « r- ^ ? c, - 2 60 s = ° O u) c a; 0^ a •a 1' TJ S 2 • :; = o li 2 55 2 a § ■? S C8 !- to rt o -"^ 5 S a a. o =■ o 5 ;o — "O y ts o o o o o o o o o c o o o o o o o o o o o o o o o o o o o o o o 00 00 GJ in t- f* oi o o o* o a a o a, ZJ w CJ c d o oT I' 01 o c^i c^a o o I. I- >> o o cJ (iTA'HO.\ I'KOCKSS i i .i ,^ -^ -r \ri -^ I' :5 c-3 CO 0-2 -T-!'!-: •-; — ooo ^ ^ o yy. ■^ ^ ^ -^ c^ m" ?i ci ■o r; Of -^ -v -^ o C^J C-O l-O W L-S LO in I.-3 CO Ol Cl CI --* O CC 00 i/S m ^ ^ 5 u — yS> ^"^ "^ =^ '^i ^ '-^ "*" "^ *^ — i! — ^^ M M I.-:: r --- :r CI CI (M cj > :3 rt ■^ M CO r-t CC -^ — a C ^ O ^ '^ 00 >0 00 ■— O o5 us a:i a> 00 ic cc od o: a: cs tf> LT IS t- oc o CYANIDK TUKATilKNT OK KI,<)TATI(IX CO.NCKNTIi ATK 217 . ro i-H O Cfl 6Ti o y. t Silver Oz. — 00 1" O t: .? '" o y. Z n I.-: 0) '"' H 01 t - ■o a o 3 O « ^^ C •a a T3 3 O 2 .C V, « c a c o 4J a o u H 2 o s 03 i T3 So «= s ■a ja >. o § ^ - O CO "3 . i--^ c-l O N •=. "5 U O -»■ ■* « 2 H a >• as >-> QQ g > U a b a ^ 0) Ml CJ r n TS A ■*-» a U a 2 -a a g u a -v o a •^ a •o -a <: < iz o o o O 3^ 00 »-H ""i t'; oi ui -* CC CO 5^ t-: t^ 03 QJ w t; s" U e a t- 0) "i' S fl =^ s OJ C n a a a u t) •a •a u 0^ a^ .^ 'O •<-» ^ ? V 00 » 2 •s s e: rt ta kl S a ■a <- gg •a a 0; 1^ •a ^ s2 "3 1 3 "S "w *rt 0) 0) Oi X X « tf K 218 llll; FI.OTAIIDN I'KilCKSS tatidii, then (Iriiiiifd liy vanuiiii on u licrizoiital liltcr-lia.v ; rc-piilpcd witli lime iiiicl cyiiiiidf solution. No. 2. Afjilatcd witli hot water, ua.slic.l hy .sottlcnu-iit and dccaii- talioii, ii.Mitiali/.fd witli liiiu- and .liritatcd with cyanide witiiout l>revioiis filtration. Cyanide treatment hy ileeantation, finally washing without water. l'i;K((ii.\ri().\ Tksts TortioiLs of till, siinie roasted charKe as were u.sed for the previoii.s tests w.'ro leaehed in tanks with a canvas tilfcr. usin-,' vacnnni to anl filtration. After wa.shi-ij; out .soluble .salts as far as possible in this way, the residue was i li.xcd with lime and tieafed by i)ercolation with cyanide .solution in the same mainier. In view of the un.satisfaetory results obtained by percolation and the tact that further extract ion was made by increased water-wiushins,'. the residue of charge No. 1 was mixed with the residue oT eharsre No. 1 treated by atritation sec Table Vi and the united char^'e HKitated further with water, then with weak cyiuiide solution and filially with water ajrain. The result of tliese te.sts indicates that tl]orouractically impossible The followinjr tests were made on another portion of roasted concentrate, to determine the influence of cyanide sfren>rtli on extraction. Hijrht tests were made: in the lirsf four a preliminary wash was given with hot salt solution. 1(1',' XaCl usiiifj 2 tons of material treated. In the remaininsr four tests the imliminarv wash was given with water alone, u.sing 4 tons ])er ton (d' material. The salt wa.sh showed some extraction of silver, but it does not appear tliat any advantage derivecl from this would warraid the additional cost. The eyainde treatment is detailed in the accompanying tables: From these results it ap 'mi-s that the extraction is scarcely aflfeeted by variation of cyanid. itrcngth within the limits and under the conditions of the tests. The cyanide consumption, however, iiicrea-ses with increasing strength. Ai>pareiitly tlie best results are obtained with a .strength of OA'I')^', K("X. Two tests were also made on another portion of roasted concen- trate from the same lot of ore to determine tlii' influence of time From this test it is evident that the gold in the roasted concen- trate is rapidly soluble in cyanide. The small insoluble portion CVWII.K TUKVTMKNT UK ll.( .TATK ).S ( . iNi intkatk l'l!t o i, . ^ M vs > N X) O (7S O .- o =■ -; d «• f-* -3 O t- O Tl C in 'x> Tz ^ T~t -^ DO on CI .^ - - r-: c: m o o c^ n Ji C" c N 'f" O Cl M m ^ CO O CO o - 5 2 " I- t' o Si M f :« CO CI «o J^ Q -t ?J O CO o ~ rt „ r, r-, ,-H •J m s - S H = ::5 w I> > «i a a I 2 2 ^ I-) rH a; t- w j__ ^ a rt c g £ £ o U. ^ o ^ *. w ^ u 0^ ? 2 i? h =^ ^ < <; O *w m CD o Q^ Pi tf 3 — . Oj a; 03 w a & a. a u u a o a 3 . "2 o o o a a >. a 5: = £ S ■'III; H.OI\l|()\ PKOCEHS M'..iMs t., I,.. ,|uit.- ir,iUT...s,sil,|,. to pn.hm^T,! tivalm.Mt „r t,, str„„.',.r solulimis. Th. foivsroiM^f trsls Mitli,i..,ill.v iM.i.,-;,!.- iliat til,. San S,.i.H.stia.i '•"■"•••"tntt... ,,ro,lu,...,l |,y tlotali,,,,, ,„,.y („■ ,,vat,.,l su,v, - ,.„||v „,, 11 .•oninicirial hasis \n t|„. „,..t|,o.l .,f r.r.usUu^. wat.T uashuitr ' a,ul .■WiMi,l,ntr. S,„„,. t..sts w,r,.. licuovr. ,aa,l.. I,y alt-Tnativ.. ,M,tlio,|s liir till' piiriMisc of comparison. Tlic jipxTssi's tliiis tried were: 1. CliloriiialioM l,y saturating' the roaslr.i rhar^;,. wit), rlilori,,.' pas uiul U'-.irhmt: uith water, as in the o|,| I'laltner pro.vss 2. Direet eyaniWe treatment of the raw ore after h'ne u'riiniin-r m u tiil.emill with steel halls. I'lH uKiN.viiox Tints _ A ehar-e of roaste,! eone.-ntrate was moisteiie,! wtih ahout 1,V; ot water, and plaee.l h,osely. withoui any paper or other lilter in a poreelain lunnel uitli Hat (.erforate,! .liaphrafr.n. Chlorine tja.s wis introduce.l from helow through the n of the f,inn,.l, and after saturation, the eharjfe was allowe.l to ...and eovered for L'4 hours It was then lea.hed out with water and the resi.lue .iried ami assaye.l. The oxtraetion was found hy dit!Vrenee of head and tail assays; it was also eheek.^l hy preeipitatin- the filtrate with ferrous sulphate, allowm- to settle a.ul eoUcetin- the deposited j,old ,.,i a hltcr. T'l^s ,. dried ;;,ei -upeiled. In one ease the residue after ehlorination was further treated hy agitation with eyani.lc. The results obtalne.i hv ehlorination are detailed in the accompanying tahle. The residue from te.st No. :i (Tahle X) was further treated hv eyanide, hy agitation for 4 days with a solution originally at U 2^{ KCN, and increased toward the end of the treatment to 05% XCN using a dilution of :i:l This treatment yielded the following re.sults' Gold, Silver, Final residue after cyanide treatment q.OT 0*8" p:xtrartion fron; rhlorinalicin lailinK ^i^ ,' Total extraction from raw concentrate... no', ,„', From the.se figuivs it w.mld seem that the results to he expected from ehlorination, or from ehlorination followed hv cvanide a-e in n.. way superior to those ohtainable hy water- washhrn" nn,I evVn;..., iMM.er metlio,! will give a satisfactory extraction and tli.-' ehoi.v would depend on nOativ.. cost undei local conditions. • VWII.K TUKMMKNT OK H^)TVIIO\ CnNcKNTu vTK 2:>.\ DlUKT (VAMDlMi UK Hwv ()he ll IS iiifivstintr (<• (oi.iparc tli,' ivsulls ^htaincd on this orv l,y ilirc,-t cyani.lidf? wilh„ut any form of .■onr.iitiation, wi'li tl:o«. jriven liy tlic conitiiiiHtion of riotation and cyanulc. Thf followini,' l.sts w.'iv miuif on portions of tli,. same lot of or.' as was us.mI for t.'st.s detailed in tlio preceding tal.lcs. Thr... rli.irir.'S uvn- tn.at..d; llu- lirst tu., wre tak.n Inn., a porti.,r. -^'''l"''- of total value. T T ^r-' "°"' ''-- Concentrate ... ion- .. -.. Tai.in. ::;;:i ;;;;;;, '"^ y> .oxs We have. tluTcfore. per ton of raw ore Gold ' ,. '," ' Recovered ^ron, concentrate: o.. ' Oold. of "^al ^^d •k;,:, V „.12!.7 X O.-tS = O.SliO |,7.u; O.S70:i V 0.773 = 0.0-7 0.70 4 1 Total recovery n.Sfi7 $17.92 ^ "''•■»•'' ".,99,5 ,s.54 loo' Takiiii: the fi^rure of Test .\'o. :i ( T;,l,I,. \'J\ .... ;.,.i.. ...:. . ., po*.,hie recovery by dinvt cyanide treat.nent' we ha ve • ' ^ "'' '"' rYAMI>K TKKVTMKNT OF FI.OT ATI.IX CONCKNTKATK L'2:{ Gold, Oz. By (iiit-i t (■yaiiiciiiiK ,) yj Additional rfcovi-ry liy (■onil)iiuf! inetlind.. ii.u>7 I'crieiitage Gold of total sold. $ir>.:'.o M>.7 -'.«:; 14.1 Her ton of concent rate. Flotation, l.,c. ,,er ton of ore = '^AL^J^ ^ fi,-,-, Roastini; Kxtia labor, etc.. in cyanidinR. 13 ).no 0..J0 Per ton of raw ore, 3.75 X 0.1297 = o.36 Net savini; by combined method 2 on In ad.litiot, t„ this the,-(. is a savi,,;. m ryan„l, coiismnptio,, as Idllows. per toil of raw ore: Cyanide Hy direct ttea.ment eon..t,med, Hy combined treatment: iblJ- Concentrate (say. .", lb. per Ion 1 .5 y 013 __ „ ,.- „ Tailin.r. I.4 .• o.s7 _'_■ ~ ! 1.77 slunving a .savin- i„ cyani,!,. nf L'.ill) 11>.; taki.i- cvani,!.. at Hie jkt \h ol KCN L.(,u.valent, tliis w,.ul.l anioin.t to 48e. per ton of raw oro treate.]. hnn^^injr tlie total savin^r ,„ .^2.74 or abotU $I)CO() on a moiitlily nntptit of :ir)0(l tons. The tests friven in Tal.le \o. m show that about 0,4^ of copper Of .s lb. p, ,• t„n of raw coneentrat.. lin this ease 2 lb per ton of raw ore-, can b,. extra..te,i in a solnble f„r,„, an,l nii-bt be re,.ov,.re,l as an additional source of revenue. 224 rUK ir.oT ATKiN I'HiicKSS FLOTATION ON GOLD ORES I From ihf- Minttxj and Si uiilifir Pitss. of Xovrniljti- L'O. laifj) Tlh' lvliti,r: Sir— I was very niiicli iiitt'i-fstcd in liir iiitorvicw witli Mr. i'.uttors iippoariiiK ill ymir issue of August 21, lit]'). Flotation proinisvs in the future to taiie a very important part in the treatment of sul|)hiile gold ores. It is goinir to he a serious competitor to the eyaiiide i)roeess, especially wiiere tiie jire.-ious metals are locked up within the suli)hides. At the present time there are many mills treating low-gradi' gold ores in California. Alaska, and Korea that employ oidy amalgamation ami watei-coiicenlration (tables iMid vanners . the tailing being too low for a further profit- able treatment by cyanidation. Concentration le.^ults will no doubt in the future be improved by the application of flotation to the treatment of tlie slime. The extraction of sulphides from the .sand can be done cheaply and efTiciently on Wilfley or Card tables. The weakness of waf. r- concentration methods duiing the past has been with the treatment of that proiiuet iia.^sinir a 2(in.mesh screen commonly called 'slinn'." The best concentrators on the market today make only an incomplete saving of the fine float sulphide mineral which in many ca.ses accounts for a good part of the gold cscapinsr in the final tailing. Flotation is the remedy. The Suan gold mine in Korea is an example. There are a innnber of low-grade sulphide ores (Oriental Con- solidated in Korea and the Ahuska TreadwelH that do not require to be crushed finer than 2.',-mesh in order to free the sulphides from the gangne. Woidd such a coarse product, where a I'onsiderable portion of the stdphide remains on a 40 or fjO-mcsb screen, be suit- able for an all-flotation process? I am inclined to favor in such cases a combination i)roce.ss consisting of fables for sand and flotation for slime. Where the .stdphide minerals are finely dis.seminated throughout an ore and comparatively fine griiKliriL' is neces.sary, I should think an all-flotation process would then be in order. However, those of us who have to do with the design of plants would insist upon large-scale tests before deciding on a flow-sheet. Tt is tnoncy wisely spent where big sums of money are involved in the final plant. A. E. Driicker. T.a Snlada. Colondiia. October D. Till Kl.KCTKICM. ■I'lll.oin <)l ILolWI'MlN THE ELECTRICAL THEORY OF FLOTATION By Tjiomas Jl. IJ.uns, Jh. (From the ilininrj and Schnti/ic Press o( Novtmber 27, iyi5) Intkoductiox. If one turns to 'Eleiiientary Lessons in Eleetrieity and Magnetism,' liy Silvanus Thompson anil studies the fundamental prineijiles of frietional eleetrieity. as sriveii in Chapter 1, a clearer idea of the causes of 'flotation' may he ohtained. After seeing a few experiments, sui'h a.s were performed at the (';use School of Applied S' -enee early in the year, it is not a dinicult matter to lielicve that most of the phenomena are electrical in nature. For instance, if powdered galena ore, with a limestone gangue. he drojjped into pure water, most of the powder will immediately sink to the hottoin. As the air enelo.sed hy the particles is expelled gradually, one sees the f(U'miition of 'armored' huhhles, some of which may last for days. Here is flotation without oil or acid. If nitric acid is added, the gas bubbles, formed by the action nf the acid on the gangue, will carry wj) paiticles of galena, some reaching the surface and bursting, while others too heavily h)ali.n.. These may be illus- trated l)y .suspending two light sjiheres of <-on(luctint,' materials near each <,thcr by means of silk Ihread.s. Tpon charging the spheres vitli like electric eharg.s. they will rej.el cadi other, but if a c(uiduct(,r isl)n)uglil toward them, both are attracted to the conductor. Of cours.'. if the spheres tmicli the conductor and the conductor is grounded, then the spheres lose their charges. If the ,.on.luctor IS insulated from the ground, then upon contact with the s|)hen s. the condmdor receives a .similar charge and the .spheres will be repelled. Suppose that the s.oheres or conductor are covered with an insulating film. Then the spheres and conductor wouid remain .t.s eiu.sc ioKciher as tiie liims wouid permit. Ho air bulibles thrt are el.'ctriti.'d will attract conductors near them that are free to move. Tin; Ki.KcTKir.'.i. tiikokv of floi mion Air, lifiiit,' ii i)()or conductor of olctricity. tlic l)iilililc.s as a wliole do not disdiar^'c immediately upon contact with a coniinctor. The only part of tlie surt'aie diseharfred is tiiat in iiiiiiiediate contact with the condnctor, and this dischartrcd tiliii of air acts as a dielectric and non-condnctor to the rest of the hulihle, whieh remains cliarf;ed. The amount of eicctrificatii.n of the huhhie will depend on various conditions, sudi, for example, as the amount of friction jiroduccd liy the l)lades of a Minerals Separation machine. Increa.se the speed and the electrification is fjreater and the attraction fm nducloi's will increase, rcduciiifr the proportion of conductors in the tailinir. Hefcrrin^' to 1). <;. Campliell's article in the Mitiiiifi uml h')i,iini( rim/ World of January 17. lf»14, the speed of agitation and the percentatre of extraction is priven as follows: speed of lilaries, r.p.ni. 1 soo 121)0 900 i;oo The extraction seems to vary directly as the sijuare root ot the increase in speed. But it will be ohsorved that with the increased extraction, the percentage of sulphide in the concentrate decniLscs. due to the attraction of the small particles of mixed gantrue and suli)liide. If the huhhles are hifihly eharjied. the concentrate will not he as clean in a particular case, as if they were less charged. \'apors and gases may he highly electriticd. The Armstrong hydro-electric machine, devised hy Lord Armstrong, gave sparks of 5 to 6 feet. The friction of a jet of steam through a wooden nozzle generates the charge on tlie particles of condensed water. Rkl.vtivk ('DNnrcTiviTY. From the ahov, it appears that to float a mineral, it nuist he a conductoi-. The following table "' relative conductivities is taken from Landolt I5oriistein 'Pliysikalifch- Chemis<'he Tabellen.' ^'^\2. fourth edition; action. n"eii;tit of proili '■'r fJm. t;8 :!!♦ .-)4 32 46 2« .'!9 18 Silver tJSl.OOO Copper 634.000 Gold 455.000 Iron 113.000 Covellite 8,000 Galena 3,3.")0 Graiihite 700 Pyrrhotite 119 Chalcorite 91 Pyrite 41.7 Magnetite 1.24 Chalropyritp 0.9X3 ManRanes<> di-oxide 0,16 Cuprite 0.025 oiderite 0.00014 Quartz ns;44viOii Diamond 0.211X10'* 228 ■nii: ii.irr\ri(i.\ rnorKss l''-'"ii 'Ins lahi... it w„ul,l scrm that tlir metals an,l sulphi.irs that may Im- ,vrnviv,l l,y tlh^ tlolatinn ,n,-tlin,l arc all .M>,„lurt.,rs llu. ,.lialro|,yf.ir li-iuv MviMs l,.w, l.ut the H„lati(.n i>rop(.rti,.,s .,f suipln,!,. >ninr,v|.s vary, a.nl the variali,... i„ the cm livitv „f tlic (htr.Tr.it iiii.i.rals may havr s.ml^tlli^^' \o ,1„ with this "tIi.. 1" tt.T !!.,■ cMiductivity „r thr valiial.je mii.rral. the easier is it floated, othei' taetiifs reinairiiii;,' the same. TiiK iNsn.vTiN.; Film, The next imi)ortai,t .|uestio., i„ the prohlem IS the a.-tm,i „f the „ils, resins, or other ajr.'Mts now nseti in Holation. Wnrkin- from the eh-.tri,.,] .standpoint, it is neeessarv to prevent the ehar-.- of the hiiblile fro,,, heinsr dis.sipated and thus l.reaking down the froth, b..fore it has done its dniv. Oils an.l other sui)stanees have a t,.n,leney to eoat tl,. metals and minerals that are recovered by Hofation, an.l if the air bubble ,> eompbtelv surroui„le,l l,y these partieles, an envelope „f oil or other dieleetri'c will insulate tl,.. bulible an.l prevent th.. dis.sipation of the ehan'e Without a dieleetrie Him abo.it the bubble no permanent froth voidd Ix' tormed. It is, therefore, i,e essary to au|uall/ jxoo.l insulators an' not neeessarily equally pood dieleetries Air an,i -lass are far better insulators than ebonite or parat^n,., but the induetive influenee aets more strongly aeross a slab of frlas,s than aero.s,s a .slab of ebonite or parafiRne of equal thiekne.ss "and better stil! .M.ro.ss the.se than aero.ss a la.ver of air of the same thickness. It may, therefore, be pos.sibl- to use a frothiti? agent, as is well known, that is n(,t an oil at all. T have done this and formed froth that has lasted for weeks. For in.stance, if in the experiment mentioned in the first part of this artich', with fralena ore. a little alcohol is first mi.xed with the fralena. before the water and acid is added. th<.n a heavy mass of bubbles and galena particles will be formed, too lu'avy to rise to thi' surface. As the influence .;f the charge acts inversely as the thickness of the tilm, it is imperative that some dielectric be used that will create a very thin film about the valuable mineral. The dielecfne mns! als,) be of such a character as to aid the formation of a great 'Piantiiy of small ],ubbles in the li,p,id. It is dinicult to er:'ate and Till-; KI.KCTIUCM. TIII-:c)KY uF KI.OTATKIN •22!< iiiaiiitaiii sinall Itulil.k's in pure water. It is her.' that .surface tension phenomena prohal)ly play a part in flotation. AciniTY OK THE rri.r. In .Mr. ('aiMi)Iicll 's arti.-h" lie ^Mv.•s thr folhiwiiiK results of aciil variations: '^*'''' K.\tra(tioii. Wtiuhl of inodiKt. -'"• ',; G.n '•••J t!3 67 "■2 50 60 "■* r,x 35 "•'' 48 m "■>* 40 v« Oilier tests also .sliow tliat the e.xtraction decreases as the acidity 111. rcases, but the amount of gaii{,'iie in the concentrate decreases much more rapidly. With an acidiHcd pulp, a cleaner concentrate is obtained. ALso better results are obtained if the acid is added before the oil to the a«itation-tank. As to the action of acids and alkaline substances in the pulp, little seems to be known, liut according? to the electrical theory, the addition of the.se .substances causes the conductivity of the pulp to increase preatly. It is a po.s.sibility that if the acid is not added before the oil, the gangue, oil, and conductors are all electrically charged by rea.son of the friction. The conductors would be positively charged, while the other .sub.stances and the air bubbles would be negatively charged. If the pulp is a poor conductor, as it would be if water is not acitlified or otherwise made a conductor (pure water being a very poor conductor), the charges on the gangue materials would remain for some time and the conductor (sulphides, e*. would attract the gangue as well as the Imbbles and oil, thus causing gangue to be taken up with the Inibliles. By the addition of acid, the charges on the surface of the solids are discharged to tlie grouiiil. and the bubbles and the oil, which will not l)e instantly discharged as are the solids, will attract the conductors. CoNCLcsioNS. It might be stated here that the electrical theory was taught last year, as possibly e.xplaining flotation phenomena, to the class in ore-dressing, at the Ca.se School of Applied Science. The above mentioned method of floating conductors may be u.sed for the rapid determination of certain ingredients in ores that are amenable to the flotation process. It requires only a beaker and a ^o\v clicinicnle nn flnf-i + w^ti Tvin/il.i,,^..^ L.^;.,™ 1 „ .i i.i , .. ^i ■ , '. " : ■. ' ••■"=- ==•-•:■-■ rvi- im- rapi,; approximate determination of insoluble in a smelting ore. the method will give a fair result within a few minutes. If the condiutor is i:ut iiii: I [,(i-r\-ii,i\ riiiicK.-s ivadily ari,.,l upmi h.v niiri,. .■i<'i.|. Ihr ivsiilis may ii,,t hf satisfju'tca-v, '"" ''> a.l.lition „f ,,|,.i,. ;iri,l th.' (lissnlviiiL' a.'ti.ii. of til.- an, I "is rcilufril. The •■■■n. wirier siiiiiiiiary .,f Ihr iv,|uitvirH'rit.s \\,r -H.-tation.' ,m,ii. Mil. IV, 1 I'r,,!,, til,' i'l,','tii,-Ml stan,lp,iiiit, may I,,. ,,f j)racli,-id ii.s.- : 1. Orvs ,'<.iitaiiiiri^' valuahl.' mimTals ,,r m.'lals that aiv iron.l '■'.n.lu.'tnrs iirv thf .miy .m.-s that aiv siiilahl,' tor Hotatidti. 2. Tn hiKiy th.'s,' , -Mil, 111, 'tors, it is iH'.'.'ssary t.i siipi)ly ..iKiiifrli clo.-ti-iticl liiihhics fi'om Im'Iiixv ti. t1,,at parti.-lcs i,( th,' coiKiiict.M's that aiT attra.-tcl: hcii,'.. tli,. small.T the buhhk.. th,' lu'ttcr th,. ivsult. th,' amiiniit nf tras li.'iii>r th.' sam,'. :'. Som." (Ii.-k','tii,- fluid is iic.'pssary to rdvcr tin- poiiductor or the Imlihl.'. to [>r,'v.'iit th.^ dissipation .d" the clci'tri,' cjiarfrc. The tliinniT the film of di.dc.'tric ami th,' iri-.'ati'r its ,lii'l,','ti'i,- stivii-rth, th.^ ^'nat.T th.' .'tV.vtiv.' attra.-liv,' \'„rrr ami tli.' iimi-,' ixTinaiuMit will li,' th(> froth. 4. Som.' mat. 'rial iiiiist 1,.' ad.l.'.l to thi' wat.'r t.> iiicr.'a.sc its ooiidiii'tivity, to ohtaiii a .'haii .'oii.'.Mitratc : ari.ls in small .piantity arc now uwd. NOTKS ON ri.iil'Al'lilN L>:il NOTES ON FLOTATION \iy .]. M. Cm. LOW iFiorn the Mniiii!/ ami Si i' ntifl, I'lrss of Dproiiiber 4, ]9ir, i •IIisTdUirAi, SKiicii. Th.' sfl.'ctisr actiiiii (if oil for lustn.iis iniiicrals \v;i.s lii-sl disclciscd by llayrifs in istio. In LSH."), Carrie Ev.TSon clalioratfd this idra and also disrlos.'.! tlic fa.-t that ai-id itiert-aj-cd the so-called scU'ctivc aetion. Her patent ealled for oils, eitlier animal, vejietal. or mineral, and also an acid or salt. The pr(R-cs.s was tried on a praetieal seale lioth at Baker City and Leadville m l.SM!); it failed, tirst. heeaiise. as has sine,, heeti shown, of the un- suitability of the ore to tlotaliou; sei'ond. because her invention was too far in advance of tln^ times. Thou followed the KImore brr)!hers. first with their bulk-oil process and later with their vacuum sehenie. The ba.sic principles of oil-Hotutioii were undoubtedly eov,.red by the above inventors and the work that has lieen done since their time has been merely a buildiiifr iij) on frroiind-work laid down by them. Differ- ent kinds of oil, ditTerent (juantities of oil. and all tin- varyini: deu'ives of agitation were all e.xemplitied and pra<'tised by them in one pha.se or another; the developments that have since been made are but e|aborations of the fundamentJil principles laid down by llaynes. Ever.soii, and the Elmore brothers. In l')02 we saw the development of the Potter or Deliirat pro<'ess 111 Australia. In this no oil wa.s used, but the mineral was raised by the |.'eneralion of fras, brouirlit about by the introduction nf jieid in the pulp so that the mineral appeared on the surfaee of the sei.aiatory vessel in the form of a scum or froth buoyed by minute gas bllbl)l,^s attached to them, and thus tirst gave the .sugfre.stioii of gaseous flotation. In 1002. also, PVoment, an Italian, was granted a patent in which he coiid)iiied violent agitation with oil and gas.wis flotation, the gas being generated within tiie pulp, in much the .same way a.s in the Potter- Delprat i)roces.s. hi the same .vear, Cattermole came out with a uni(|ue .scheme. He first emulsified his pulp with a small (|uantity of oil by violent a^ntation and afterward .submitted it to a slow stirring, action in a s.'coiid machine, by which he granulated or coagulated the minerals that had been oiled into nodules, which he afterward sepa- ♦A paper originally prer.pnted at the annual meeting of the I'tah section of the American Institute of Minins Engineers, at Salt Lake City, on October 4, 1915. Read at the New York meeting in February. 1916. 232 Tin: I i.in \ ri(i\ ihock^s • 1 --... -JV Ofi-C L J:^jyr^S»<- ..r^T OTrf . 1 vKr t^rf cry „Z. : , ~; Fin. 42 rate.l from the pulp l,y Kraviiy. The .ietVvt .,f this process was tliat onlv Dnrt. nt' tin. ini...^....il ,ir„, .._„.,..i.,,^ i ,i . „ . ,■"■,. " , s=r-.::;!:.-.;v,:, ;:ic r; St or it appearing on the suriace ot the pulp as a seum or froth, and so was lost in the tailing. This rlefeet of the Catlermole process suggested the funda- Notes hn ii.nTvrrns •_':<:{ mental idea of the pr..c<..s.s aft.ruanl .Inscribed l.y Sul.nan I'iranl and iSallot ia tli.ir i.-cts, in wl.i.h, iMsfiui ,.f KraMulatini; part ,„' tiir .,uM..ral, tl.,.y Hoatcd all „f ,t. This jKit^nt f,.rtns the basis „f all the Minerals S,.paration operations. It was Hrst exi.NMlfd in Australia and m a short time rrj-haed all othrr Hotation pro,.,..s.s..s i„ tJK.t i-oiintry. In 1!»()4. Ma.'.piistr,, bron-lit onl his tub,. pro,e.s.s a very in sren.m.s sehen.e whi.^h -ave exeell,,,! .-esuKs on (he san.iv -tion of the feed but was ino,„rative when slime was present. This was a strictly surfaw-tension seheme. an,! its inability to handle slime was a se.";)iis liiiiitatioii. In 1912, Hyde introdured a tno.lilieation of the Minerals S,.pnn tion proress into the mill of the Hutte & Superior eomi.anv at Hutle Montana This ditl'ered fnmi the reirnlar prarti,-e in 'that it in- troduced a doulile treatment, first ■roudnnir' ami then 'eleauin-' the eoneentrate. Vsr.VMXvir l',.nT.vTi„N-. Karly in UKilt, f ,h,l .., j,,„,t ,],;,| „,• ,„„i. with the Mae,,uisten flotation proee.ss and in the in.stallation of the tube.plant of the Mor.iin- ndll at Mullati. Malio. This work was tollowed by a lar-.- amount „( e.xperiin<.ntin- on the difT,.re„t kin.ls ot existing flotation proees,ses. the outeom.. of which was the develop- ment of the pneumatic method. The first application of i.neumatic flotation f.,r the treatment of ore was ma,K by me at the mill of the National Copper Co at Mullan I his plant was .lesiumed and built by „„. and was a smress i„ ,.verv way from th.^ very start. Construction was started on Autriist 14 ^fm. and the plant went into successful operation about April lo' lf114. The flowsheet is friven in Kifr. 42. Since that .late, the metlio,! has been a(h)pted hv nearlv ■;'; the other mills in the Coenr d'Alene tn-atinr; lea.l and lea.l-zinc ores notably the Cold Hunter. Mornin?. Hercule.s, Hunker Hill & Sullivui' Caledonia. Last Chance, He..la. Standard, etc.. a total of about T.n cells u, all. treating from If.on to 2000 tons of slime and fine sand i,er day. The same m-thod also has since been adopte.l bv th,. Inspiration Arizona, Anacon.i;uO' Iiiji.-> pel' ua,\ . The flow-sheets of the Inspiration and the Arizona Copper plants are given in Fig. 4.1 an.l 44. The Daly Judge flow-sheet, in Fig. 45. is ->.!» nil. I i.iiiMiMN n(,Mi,>s Fjo. 43. iUi iiiluresliii- example uf fl„. ncoverios possible on zinc-lead fine sand, and slinie. , "" " ' -•■••s •!:a^:a:::, r r^. jo. HiuoiialeM iiie various Clements composing the Callow method. .1 is a mi.xer operated l.y eompress ci.s |.r,oi- \rui\ L':!.-) •""1 .•-MulMlyinK tlK. oil, ,|„. a,,, ,„„, „„. uat..,-, tl... snuu- U,,r ,„' ^MTan,lu. I,,.,n^,n,.. „„,„„„ us,. „,,.,aM„l,.u„M< h, .as.., u In.,-,. 1 1,,- |-" 1 th.s nnx..r, or i'a,.l„„.a tank, ran l.- ..|n,n„at..,|, .s,. that tl,.. .,,1 ,s I'.l 'Invrt nit,. tl„. ,Mili aii.l tli..,!,,- into tli. s..,,arato,-%- ,.,.11 It l.a.s l„.,.n ,.r,.v,..l .....■.■li,,siv,.|y t|,a, aritati,,,, p/r .„ is „„! ,„■,•..^ ";''• •" ••^"'•'•-'■"l tl„tati,M, l.ytl,,. p„,.un,alH.,„,.llH„l, I,,,,, f,!,.. pa,.,:, a I'a,.|n.,.a mun,.,- f,,,- ,.a,.l, f,,,,,- n„.»:l,iM«-,-,.lls was install,,! Ins n.,..n,.,l .1,,. ,|,i,.k..n..,l ,V..,1 fmn. a l)„n- tank, win,.), ,V,.,| was •■ .■vat-.l l,v a (,..lt.an.l-l,u,.k,.t d-vator. Tl,.. ..i| was r...| int„ tl,.. 1 , "' ";■ "l':7'""- "'"I ""• -Hxintr tl,..,... s..,.v..,l all |„.,-,,.,s,.s, s,n,... ,|,.. n-l,sw,,,,,,,. ,1, ,.,H,,,,.asw,.,... ,on.,,M,.,,.,j,,s, ^ , as with tli'-m. I|,,.n.,,„,,„,,„s,..,f,l„.„, ,„„,is,,|,„„,,,sl n al,an.i.„„..l i is th,. „„t,al .„• ,„„^rl,in^. s,.,.a,-,it..ry .-..H. j, ,.„„sists .,f a ank '•"-.'Mt^.l„„,„v..,.allan,i24in.ui,l...withal„.tt,„ni„,.li„..,| . on, ._,.. 4 ,„,.l„.s „r all p,.,. ,„,„ ; „ ,s,Oin. at ,1,.. shallow '"V ;"• ''""'"'" •!"■ 'l-l.-.st ..„.!. It n,ay I,.. 1„.,|, ,„■,.;„„,,. St. ..-I or w..,.,|. pr..f..,-al,ly w,,o,l. Fifr. 47 an.l 4S sl,.,w tl„ ..,.11 i,, .iHail. Tl„. hott..,,. ..f ,|,„ ,ank .-on. .si.st.s 01 a pun.us n.,..li,„„ n,a,le „r f„ur thi..kn.>s.s.>s of l„„s..lv ;w,v..„ io'ni'Vr; i ';■■''"■'■'''. ""'""■""' ' •■ " '""'^'"^ "•' '"•'••■'"-"■'' -'"■ " I— nt l,ul.„,s wl...„ ,.n,l..r air-pn-ssn,-... Tl„...„,,l. ,|,is p„,.„.s ''""" '■"•"•'•••'--^■•l "u- is f..,-,....l ,,.v „„. ,,,,„,„, ,. p,,^,,,,^ ,,^.,^ ';'• '"'.V otl,..r ,...,.a,„i.. ,nat.M.iaI n,ay I,.. „s..,l t., ..nsn,v tl„. n,.....ssarv .n. ^ ,,,v,.o„ .,, „,e ai,-. Son..- .,f ,l„.so „av.. 1....... tri,..i. Unt .o,- .ra.t,cal an.l ,„....l,an„.al r,.i.sons tl,e lo.,.s,.ly w.,v..,. ..anvas-twill s....n,s to serve all purposes hotter tl.a,. anytl.i,,^ els,., an-l has he..,. a.l..pte.i as th.' stan.iai-il pomii.s-hi.tton. eonst,-i„.tioi. The spa..e ,„..Ien,..ath this p.,-.„.s n,..]i.,.,n or i,otto,n is snh.livi.i..,! a -e'w thT'"'"''''"''-^' '.■-'■;—<> '".v an in.livi.iua. pipe a... %ahe «,th the „,a„. a.,--p,pe F. Hy ,his n,..ans the air-pressure to oaeh eo,npart,nent .-a., he r,.gulate,l . l.y throttling the valv.O to -m-spo,„ w,th the varyin, hy.lraulie hea.i withi,. the Lk L as to dLScharpe a un.fonn a,no,.,.t of air tl,n,ugh.„,t the len^rfh of tlu> Lotto,,, an.l n.a.ntain a uniform aeration of the eontents A pressure ot fn>,n 4 to 5 Ih. is generally use,! and eaeh square foot of porous med.um re.,uir.>s fro.n 8 to 10 eubic feet of free air per minute. 1'^' „ ^'■■'■•":cii riiK!- ;;; mr tank is |)rovid.'d with a lin and a., overflow fitter for the reeeption of the froth to be disehar^d The lower end of the tank is furnished with a spi^ot-disehar^e 236 TH£ FLOTATION I'HOCKSS ■f*^ »„e ^mmi r Flu. 44. Mtt.Mi with a plufT-vnlv... ,.,„.rate.l by ., float, for tl, purpose of '■ui.ntammf. a u.nforni wat.r ],.v,.l within fh. tank, thus in t.ir., s.r..r.ng a u.nlonn a.ui constant .iisd.arp. of iVoth und...- all th- Iho wator-lovel may, ot cours... h. varied : In.t it is n.snally maintain,.! NUTKS ox Kr.OTATlox 2r, "t ■'t-ut 10 to 12 i„cla.s lH.|ow the lovd of ,),.. overflow-lips The a. m, ,s . ..ha...., thro,.,,, U. spigot and the frothy c-on^^.trate o.n v,.d hy ,aea„s ot th. .s,.l..-j,„ttors to the pump D4. theuee to the deaner-separatory .ells n.arked C. This cleaner^ell is . ...aehin ot the san.e eonstru,.t,o„ a.s the rougher: in operation, however it ;: i;:;:^, k' ;'>; ^ ^-'-/--i^— ^ ♦'-' taiii„g fro,;. t,. ^ ;.; s pumped l.y />-2 ha,.k to the original f,.ed. and thus a elose.l eirenit na.n.a..,ed on th.s portion of the feed. The eoneentrate fro.n e eaner .s tue sh.pp.ng or finished product. Dump l>., can well e .' hm„,ated hy sHtmg the eleaner at a h.uer elevation and eonl i^ |lH-o.|.he.-froth to .t hy gravity. Tsually one eleaner serves n>ur f'AKA. ..K,. OR S..:h.ks. The maehine n.ay he ru,. either u, parallel 1 .eli... Recent e.xper.ence goes to show that. o.. so„,e o.-es at least e se.-.es treatmct gives a slightly better tailing; on others it does ot. I ,s unne,.essnry to extend this ar,.ange,nent of cells beyond .cells ... ser.es In a heavily n.inerali.ed ore this arrange,."' i' t 7; T"": ""' ■" ""'^ " '''' *"" ■•""^•'--onc;:ntrate m.ght be of lugh enough grade to omit the re-cleaning operation the onV TN " T"' ""' ^" *'" ^""^■•^ '"'^"'t '- r.;u.-ned , to he ong,nal feed .n the same way that the tailing is returned from number of such combu.at.ons is possible. At the In.spiration the ongtnal fee, goes to 12 prin.ary roughers. the tailings'from wh h a class.hed ...to sand and slime, the sand going to tables and sl.n.e be.ng returned to 12 secondary roughe.-s. The concentrate fron. both the pr.n.ary a..d .seco..darv roughers go to fou t^;^ and the cleaner-ta.ling hack into circuit F,.oT,t Fo.^MAT,ox. The froth is generated as ti,e result of >n.iect,ng the tl,.ely divided air into the bottom of the re,dv :-.,ls.hed nup; .t eonti....es to form and to ove,-flow so lo... as ..nnshed w.th p,.lp of the r-roper consistence, prope,.lv .. :>ll' » .0 nght ,,uan„ty and kin-i of oil or frothing a.^en, Measured :;;; T't: i7 r' ^•"•;" r *'•"'• ""' *■'•"'" '""""'-^ -"- ^^ Horn 14 to ](, niehes m depth or tbickm^ .,, i r , 1 , „ ' jiii i>i 11,11 Kuiss. aiicl accordmt' to the < .aracer of ore, k.nd and quantity of oil ,.,rod,.ced, will ,e „ T lc.s volum.nous. .-oarse or fine grained, d.-y or waterv-all of -"-I't.ons be.ng ad.justed by the regulation of the Ui,',, „.. J.l^Z •" '"1 an. I ine quanfify of air injected ' ■' In the case of so„,e ores, rien'.n sulphides, when a con.pa.-atively 238 TIIK KI.OTATIu.V I'UOCKS — D»Lr- Judge Mili TcsT N' 34. Fir, 4n. lou-.grade .on...,,. rat. w,ll sutli,.,, ,h, ■,,,,,„,,■ ,„^,, „„j ,,^, „„„,.^^^,,.^. '■•" on l.nv-.ra,i,. ores havin,. a l,igh ratio of eon,.,.„trat.o„ ' a.ul ,, ^:n..-.:;;:t::;: j,;;,-;!;.-, a OiraiiiT is d('S!rat)li> I ii.p-DENSiTy. TlK. pulp to be treated may be of varjing density' XUTKS OX FLOTATION 239 from 2J:1 water and ore un tn 'i n»- <; i <• and sU,„e the Conner r.:!^ i^^ ^^Ir^,^; ll ]:T;J :;:::l ihe pa.ticular density ,s not a matter of so ,„,.,.!, HMportan,.. .s t ,t, . ,u. pulp re,.Mres a re-adju.tme„t of the oil-supplv. ' " 'I UMtUy ot 0,1 inereasmg i„ proportion to the inereas,>d vo nn. '" f'"'P I'Hl.'l-'.denl of its solid eontent 50 t^^^s'"'"?. ; ^ "'"'"■'' '""•■>^^*^' J''^"- ^'^^"^^--d ro„.hin,.,.ell is "II. s.iiHi ,iMetion is t, t ,1 i. •. t ' only the sinne from the prin.arv tailin- after the s... 1 . removed. This srives an aver.-e of W' ♦" "' '"''" A- „ ' ■'^'^'^*'"' "t •^■>'> tons per roil.' I n"-eell Th,. - «:* rou^hers run in parallel, and 18 el ane J ;\" .,';:"f ' approximately 57 tons per rou.hinreell, or 4"' t ns pj rf I'oiisrhiiisj and eleaninp. '^ " ''"' Some tests have shown little differenee in r,.eoverv «1, m n.nn>ns 45 tons to the eell or 65- hut the r. "."""'■'■ "'"""'• on --lea. ore .5 tons per eell is an average ol^.lr ' ' '"•"•tors. Ill,, puie-oils are frood frothers- m.,! t-.,. . 1 •. Mihdivisions ,,re ^.ood eolleelors O, I ' "" '""'"""- <-....l-l,>r. 40C, „„„,,„ „„„„„. ,„„ „^^^, ^^^_, ^^,,, ^, ^^^ ,1 .i» 1>4(I IIIK Fl.nTATluN I'liOCK? the Daly-Jiidiic we usrd 4(t'; cnnlc coal-tar. 40',; creosote. 20'; I)iiieoil. Ill the Coeur iTAleiie on zinc ore we used straijrht wood- creosote: on the Xalidiial I'opper ore |)lain tiiri)eiitiiic will work. liwt pine-oil is helter Tiftntiftv- III' Mill T>iivfiif. At tile Inspiration we used from U to 2 .* ♦l.„ lA,.!.. T.. 1,-. and at the National 0.:i Ih. ■ ;i is suiHcient. In the experimental work at another plant the coiisuiiiption of oil was approximately one pound NOTES ON FLOTATION 241 of mixture pur ton, but sincp the outire plant has l)et'ii in operation and the eirciiit-water is reclaimed and used ov.t iigaiii, tlie oil eonsumption ha-s dropped from 1 to O.-'k') lb. The proper kind or kinds of oil and the quantity requisite eaii oidy be determined at present by tentative experiment; so far no scientilie short-eut is known. CiiAiucTER OK FiiOTir. The nature of the froth made by the pneumatie method has the distinctive characteristi" of being iinstabh- or ephemeral, that is, it quickly dies when removed from the action of the injected air. The bubbles composinf< the froth, beinfr generated under a hydraulic pns.Mire varyinj; from M to 40 iiiciics, on rising above the water and to the froth level, burst by reason of the lower surrounding atmospheric pressure. On bursting, they release the mineral attached to them, but this in turn is caught up by those bubbles immediately following behind. The instability or stability of the bubbles will depend, to some extert. upon the oil used anil the nature of the gangiie. I'ine-oil makes a very brittle froth, which liies immediately on arriving at. the surface. Creosote and light oil make a more elastic envelope, which at times wi!i expand into bubbles 3 to 4 inches in diameter before bursting. The pine-oil l)ubbles will rarely be over i or i inch diameter. Ca.stor-oil, olive-oil. candle- makers' oil (oleic acid), palm-oil. sperm-oil. and other oils of n lubricating nature, have in general been replaced by oils more or less soluble or miscible in .■■ntpr— such .-ls turpentine, pine-oil, and all the coal and wood-tar distillations. The v,ry volatile oils, siidi as naphtha, gasoline, ether, alcohol, seem to serve very little purpose except as a means for making the pitchy ingredients of tiie tars more soluble or miscible. A large, coarse, and elastic bubble seems necessary to tlie recovery of coarse-grained mineral, but for the very fine or colloidal mineral, a small and comparatively brittle- bubble is necciwary. PowEK. The National ropi)er Co.. using approximately O.W cubic feet of air at 4 lb. pres.sure, and treating 500 tons per day on « roughers and 2 cleaners, required :ir)-hp. : this equals ^.') hp. per cell, or 12.53 tons per hoi-se-power, or 1.25 ku. -hours per ton. Another conspany u.sing ai>pniNimately <1600 cubic feet of air at 5-lb. pressure and treating 2400 tons per day on 48 roughers and 12 cleaners, required 210 hp. ; this equals 3.5 hp. per cell, or 11. t5 tons per horse power, or 1 50 k^v.-h.ours ner ton The Inspiration experimental plant, using api>roximat.'ly O.^O cu. ft. of air at 5-lb. pres.sure and treating 200 tons i)er dav with 242 THE KI,()T.\TI().V I'KUCESS 1 ^Tv"-j'^-!^v^>-»4>'^^.^^4^=4^-^..i^o:r^rj^ M ./»- o NOTKS ()\ KLOTAIIoN 24:{ 4 roughers and 1 half-size cleaner required 25 lip.; deducting,' 4 hp. for two 2-in. centrifugal pumps, this equals 20 hp., or 4 hp. per cell, or 10 tons per horse-power, or 1.79 kw.-hours per ton. A maximum figure would be 2,J kw.-hours per ton of feed, using 5 to 5J-lb. air-pressure, generated by a Roots or Connersville positive blower. *** Tin: H.dTATKiN ncK KSS Cost. Tin. .,il-,„i.M„n.s K-'norally in us,, will ,.„M In..., 1.25,. ,„> to .Je. p.T II.. .Irpendinj? o,. tho j.n.,,„rtio.. of ,.,v.s.,l an.l other hiH,- priced oils .iscd, hut ] .U' nor Ih uill Iw. .. ..„.■ '., , • . '" '^'~- P*^ '"• ^^'" >'<' a sate averagro on most oils. A co„su..ipt.„„ of 1 to \\ Ih. per to., or from 1.25e to 4 5,- per ton of foe.l, s..y 21.... woul.l he a safe avej-age. The lahor." of course, ^y,ll va.-y with the size of the phu.t. At one plant cons.st.nK ot (JO ..ell.s. tuo ...en per shift operate tl entire plant oqu.valent to a eost of 1},.. per ton. (),.e ma., per shift on a 2.1()-ton' plant will mean a eost of 5,4e. per ton in n.aintc.anee. Assuming a I.le ot three ..lonths per hla.,ket and 50 tons per eell a..d an allowane.. f.,r repairs to hlowers, moto.-s. p.imp etc.. we have \e per ton as a liberal esti.nate. Power at le. per kw.hour ($60 per hp.-vear. a.,d 2.^ kw -h<...,-s per ton equals 2.;x.. per ton of feed. Summarized, my esti.nate on a 20()0-ton pl.,.,t will stand app.-oxi- iiiately as follows, in ee..ts per ton of feed : Labor Oil '■■'■'■'.'.'.'.'.'.'.'.'.'.'.'.'.'. ^-^^ Maintenanre ^-^^ Power •^•5" 2.50 Total c.vn Or, n plant of 250 tons the .-xti^a lahor wouhl bring it up to approximately lUc. per to... Actual figures f.-o.., a large plant of over 2000 tons enve fi.le. per ton. The flotation feed i.i this ease represents G0% of the erude-o.-e ton.iage or :].5e. per ton of erude ore treated. T.n:.,H,KS. So far no satisfai-toi-y explanation of flotation phe nomena has been advanced. At my instigation and u.ider my direetio,, a larg. amount of research work luus been do..e i., an earnest c.deavo," to formulate so.ne logical explanalio.i. a..,l perhaps to find s<.me scientific way of eondueti.,;. ..xperime.its in lieu of the empirical methods now in vogue. While this purpose has not vet been fullv attained, the experiments have resulte.l in the formulation of a theory that appears to be well grounded and that mav pn,ve of value to others engaged in this bra.ich of mrtallu.-gv. Much work has been ,lo.,e at the Mellen I.i.stitute at I'iit.sbu... iH.dcr the direction of Raymo.,,1 ('. lijuon. a.id lately bv .Tames A~ Block at the loenl KfntJnii ,,e <1,„ tt o i> i. ^.. '_ '_. ot some of th.s work are summarized i.. the following stateme..ts: m. NOTKS ()\ KI.OTATIiPN- lm; In .o„si.l..n„^, flu. ,.on,HM.tio„ lu-tu.-M riotatio,, i,l,..„o„H.na an.l tiio i.l.ysi.-al properti,.s ..f tl... n.in.Tals n.M.vnuMi. tlMTc arc two parallelisms to he noticed: First: [t has he..,, „otiee,l for some ti,ne that the „.i„e,-als whieh Hoate.l we,-e not easily wetted hy water, while those whieh we.^e •■asily wetted did not tend to eo,„o up with the froth. This is the ms!s ot ahont the only th-ory that has heen widely eireulated up to tl„s t,n,e. It is well state.! I,y Iloovvr in his hook, '(oneentratinp Ores hy Motat.o,,,' the first authoritativ.. puhli.>afion on the suhject S.von.l: lhe,-e ,s a parallelis,,, hetween certain .d.^efro-stati.- -■hai'aetensties and tne tlotati.M, properties of ores, as will he explain...! In the theory first menti..,,...]. it n,ay he .le,„.,nstrat,.,l hy a r.ons,. ..ration of surface tensions and contact angh, that certain floatahle minerals, such as galena, will float on the surfa.'c of still uat.T wlnle ganjrue pa,-ti..l,.s. .n, th.. other han.l. p.,s.se.ss a jrreater .■Hlh..s,ye attraction for the water than the wat.-r's cohesiye attraction tor Itself, and are therefore drawn thr..!,-!, the s,irface fil,„ into th.. int,.rior. where they sink hecaus.. of th.'ir fjreatcr spe.-ifi,. grayity rhe.se properties of floatahle minerals an.l ganjjues are increa.s^d by the p,-,.s..n,.e of oil and aci.l. Oil sti..ks to fjalena with greater t.'i.acly than it sticks to silica, and an oil surface is far less ..asiiy wett...l than a galena surface. The aci.l in the water causes a still irreater diflfei-ence in the yarious .surfa.'c tensions. This it s..ems IS without question the explanation of such flotation a.s is ohtained hy the Ma.'nuisten process, in which th.. ..,.e particles are lift.'d to the surface and those remainin- are removed hy skimming the surface layer of the lir|iiid. As r..gar, were detrimental to flotation, while others sn.'h as Congo re.l and methyline hlue. ,lid not interfere and were' If anything, heneficial. In classifying these, the i„j„ri.,us ones generally ..ame un.l..r the head of what physi.'al chemists ..all ..lectro- negatuv ,>ollo,ds. while electro-positiye .-olloids were not harmful ihis classification is derived from the fact that suspen,l..d particles will generally migrate when placed in an electric fi.l.l. and the class,fi,.at,on comes naturally from the c.irection of their migration n„s migj-ation is called el..ctro-,,hore.sis. or electrical endosmose, and ■■^' -r.w rcmiit or ii,e fact (hat the iiqui.i containing the pariicles forms eontact-lay.rs around them, similar to the surface-films formed wiien liquids come in contact with air. These contact-films almost 246 TlIK FI,()TATI(l.\ l'Hil(f> mvanahly have a .l„r,.r,.M,.. of pofntial l,Hw...n their in,,..,- an,l outer mirlaces. Thr (il,,. „f an air-water ......taet ha«, for i.mta,,,... a ci.fr..r..,H.e ot Omr, volts,- an.l oil,,.- .■oMta..t-fil,n.s lu.ve sunilar charges nus eauses the partieles to aet like eharfjed soli.ls. and to be attrueted by eiectri. eharjjes of opposite sip,, The eharsres o„ solids a„d „o„-,„i.s..ih,e li,,,nds ean I ,„v,.,„e,„lv studied on the statre of a l,lie,-oseope. This work led naturally to the sturly of th,. eha,.;es .xhibited l^v various ores and ,ni„erals, an.l in ,i„„ work an interesting, paralh.hsn, was ol,,s<.rve,l ; nan.ely. that floatable ,nine,-Ml.s see,,,,.! to have positive eha,-es and non-floatable t;antr„es nesrativ- eharL'es = So,,,,. jranp,„.s were found with positive ehar^es, but thev we.^e Huira.denstieally ha,-d to handle, havinir a tenden.v to e,;,„e „„ with the troth. These eharges son.eti.nes uny with the aeiditv or akahnity ol the li,„„d. and this variation is not ineonsistent with the etreets of acidity or .dkniinity on t|„. flotation of ores It has been noti,.ed that these ele.-tn.-statie properties .!epe,„l on the enndit.on of the surfaee of the pa.li.-les an.l not upon the co,npos,t,on of the „ias.s. Kor instanee. lea.l oxide, whieh is onlinarilv negative or neutral, when eovere,! with a sulphide eoati,,,, takes upon Itself a po.sitive eharge. AltlM.,.ph the.se eharges are sniall. ,vent work on the eoaKuh.l.on and defloeeulation of sli„,e. on the .•oaKulation and dispersion of colloids. an,l along .similar line.s. shows that the eontaet-tihn eharges have an nnportant bearing on the dispe,.si,u, or eohcrenre of particles suspended in li<,uii4. 27: ZVi and 2S: 367 'Kolloid Chcmische Reihrftc. 2S4 89: 91, 1914. y.rit. fiir Physikfilische ChemW. NOTKS ON FI.OTATllIX 24-; .; ..r... ,u,.l o„ Ih,. I,ul,l,l,.s. Sin.v oil ,.o.„a-l til,„.s and a,r .nnta.t- (' ".s have iH.th Im.,.„ pn,v...| to luiv.. ....jfativ.. ,.|,arj,^..s, th. positiv-lv '■harfr,..! minerals mi-ht a.lh..r,. to ..ill,,,-. Th,. hMl,M...n,anth.s n.'a H-.talion ma.'liin,. arr un.louht..||y co.nposci ot" oil. ,„. of oil in emulsion, since pure water alone uill not fn.tli. The sjime forees tlieri, that eau.s,- oppositivHy -har^^.,! eolloi,is l„ awlomrrate an.l preeipitaf.. eaus.- the minerals to a.lhere to the oil-eover..,l bubbles a") * In TUiiin CI KIN. 'I'lirff ^iif many nu'tlMids ul' liiiiuUiiif^ siiiid and at the leadinir tlotatinn plants in Australia. DiMiNiNii \Ni) Diw \ri:i!iNi:. It is generally advisalile to tlior- iput;hly diwatcr the risidne t'nini flotation treatment in order to form a elo.sed eireuit of liipior. This maintains constant conditions throufi^hoiit the plant and avoids waste of oil, which woidd he carried away hy the soliilioii with the tailiti?. The methods that may he used for this puri>o.si' are : (a) Filterintr in vats; ih eondjination of a suhmerfjeil drainiiiE:- iielt and Dorr thii-keners : id comhination i>f Caldecott diaiihratrm- coiies. drainiiii;-helt, and Dorr thicken«'rs. and (d' comhination of Dorr classitiers and Dorr thickeners. ^''iLTEKiNO IN V.\TS. In tliis system, shown in Via. r)0, the pulp from flotation is run direct into vats. These arc u.stially If) ft. diain.. their depth varyiiifr from 10 to 'In ft. In the centre of each, and hpfore (illin?. a tuhe or pipe. l'> in. diam., that fits over the eii'cnlar discharce-hole, is inserted. When the vat is ready for emptying, this tuhe is lifti-d out a lartre proportion of tlie tailing falling throiifrh the centre hole onto a conveyor underneath. The remainder is afterward shoveled upon the s,ime conveycn-. A wooden frame, in't shown in the sketch, is erected above the vat to support the liftinpr-ch'vice. a screw block being used +0 raise the pipe to the desired height. This operation is afterward carried out by an ordinary block and tackle. The vat may be made of wood or iron, and the height to which it may be constructed is eontrolleil hy local ciindilioiis. such as the design of the plant, and the nature and fineness of the material to he filtered. If is. however, appari'ut that the greater the height that can be ecoiiomicall.v employed, the less fill' labor rcipiired. as a proportionately large amount drops through the centre of the vat withont shoveling. This would tend to make the inner tube too long to be iianuied eonvenienii.v, hut tiie •Abstract from Min. and Evg. Review, Melbourne, AuPtralia. r)isr(isAi. Ill ii.oTM'KiN UK.^ini i. 249 dittii'iilty has been ovcrcniiic l>y iiiakiiifj tin' tiiln' in sections, each of which is lilted in its turn I'roni the to|) as cMi[)tvini.' proceeds. Tlic time of tiltcrin^f is arrnnjfcd accordiiifi to the iiiiiiiher of vats ("ii|)loyed, Iml it is tiie usual [iraetiee to run the pidp throuifli Fig. 49. al'stbalian boom-oimtbibutob. uelt-dbive.n witholt oeab at 900 n. I'KB MIN. IIV SLOW SI'K.Kl) MOTOU (O.NTBOI.LtU KBO.M BKI.OW. TME .MACHINE (AN UK .MOVED WHILE WOBKI.\(i. a number in series, so that the slime settles from the solution. Tl...., ;f „;.. ,..■•,. ..„ „ i.„ )__:,.: .. i „ ,i int=, l! -,•-■, r::.- ::•• ::: ::— . •■::r :::r.\ :,'r ufitihillo ;i:iU aiiLi'tllLI" emptying, while the remainder would he used for the . .ilp flowing, in series, througli tiicm. Tiic filtered water is carried off hv a i;)( 1 Till-: FLOTATION I'KOCESS number oi' pipes at the bottom of each vat. I'luler certain eonditious a suctiou-pmiip is eoiiiieeted to these pipes to assist tiie tilteriug, but this is lint tlie usual practice. As a filteriiig medium, cocoa-nut mattint: is used freiicrally. After a \at has been emptied, the tube is dropped into tlie discliargi-liole, two lugs, one ou each side keeping it in position. 'I'lic open space round the tube is then filled with clay. It is ad'isable to have the bottom of the vat six feet above the ground- level to allow of easy access to tlie conveyor underneath. At the spot where the sand is discharged upon the conveyor-belt, guide- doors are arranged parallel witli the belt to prevent -..uu] going over its edge, and the number of idlers under the conveyor is increased to pre\('iit it sagging under a rush of feed. The conveyor is usually a Hat belt. 24 in. wide, traveling at :J5() to -0)0 ft. per minute, 4-in. iron idlers being used. This iiietbod lias many excellent features: its advantages arc: (li The moisture of tlie drained tailing is less than in any other system: '2! the slime is drained at the stiiiie time Jis the sand: I '■] I dams for handling the slime and the cost of labor or same are eliminated: 4i dusting troubles are minimi/ed (ui the du •. owing to the slime li'>'piiig to set the tailing; (">) the angle of repose of the dump is increased, thus enabling more sand to be stacked per unit of ground-area; (6) no trouble with conveyors handling tailing will cause a stoppage in the main plant; (7) accurate sampling of l)roduets is possible, enabling shift-work to be kepi under control. Tiie disadvantages are: (1) High initial cost of erection; (2) iclatively high cost nf labor in emptying vats; (3) clarification of '.elutior. is not usually as c(unplete as is the case with other methods. ('o.MBiN.\TU)N oi Drain \(iK-HKi,T ani> Thickkners. . The idea of tiu' suhiiierged diaining-belt, I think, was first intr Jueed in connec- tion v.itli the Elmiu-e process in order to overcome the difficulty of discharging the residual pulp without upsetting the vacuum in the flotation apparatr.' In this system the belt runs inside an iron troutrh tilled with water, being forced into a semi-circnlar shape by means of a spherical pulley, a.s shown in sketch. Fig. al. The bi'll travels under water for a eertain distance, ri.sing at a slope of If) to 20 onto the bead pul'ey. The rlrive is usually from the tail-end by means of a worm- wheel on tiie tail pulley shafting. This tail-pulley is generally t) ft diam., and is faced lui iiie outside with wooden boards to give the belt a better r ?■ The fe^d is, preferably, distributed to the DISI'OS.VI. OF I-I.OTATION KKSIDIK 251 belt by means of an iron laiuider with holes in the bottom, wooden guides being arranged to guard against sand getting betwm the under side of the l)elt and the trough. The trough has side iders attached to carry tiie overflow to Dorr thickeners, the number of (E y3dld 3== ^ ^ PI 1? ^ k§J ^i CI -J a a 2 O I 10 2 9 t- o u I 2 b oo Z I I If) z o h u Ui i the latter depending on general conditions, such as nature of slime, amount of water in circulation, etc. The submerged belt forms an excellent desliming system, by reason of the classitication in the trough: its capacity is 4000 or more tons a week of mixed slime and TIIK II.CTATKIX I'liOCKi s.iii(l. The (h-aiiiiiig of tlie saml is ac('i)iiii)lislRHl as it risvs I'rom the siirt'ai-c ,'ii to tli»> liead pulley. ■//'WUXL^Cir^: ctiiiiloycd. This coiisists of an idler driven by two eeerntrics. The vihration eaused on the helt hy the idler striking it underneath nisposAi, OK n.OTATiox u;:sri)i i; 2.3;i displaces a larger quantity of water from the Siiml, and thus reduces the proportion of moisture in the final product. An iron scraper is used t'o- removing the tailing from the draining-belt ; it may he kept lender pressure by means of iron springs. This method is very good, especially where the room available for drainage is limited. It is also convenient where the height of the flotation-plant above the ground is small. The life of the belt is less than that of an ordinary draining-belt, owing to the heavy pressure of the spherical roller, and the action of the hot circuit-liquors in which the belt is sul)nierged. The labor for attendance is small. This method is at present in us(> on two of the large flotation plants at Broken IIiil. COilBINATION OF CoNKS, DRAININr.-Hla.T, A.NI) TlIICKENERS. TIlis method, diagrammatically illustrated in Fig. ')2. has been installed in the latest rtofation-plant at Hroken Hill. The size of the Caldceott cones usually employed is 12 ft. diatn. and 10 ft. deep, the diaphragm being 2 ft. to 2 ft. 6 in. from the bottom of the cone. In most cnscs a plate-diaphragm is used, but the introduction of an iron ball to serve the same purpose has been most sneeessful. Where a cone of this type is used as a thickener, rather than as a slime-cla.ssitier, more pulp may be thickeneifv p.,^n1. .«,.,.] Til, „ \ 1 II... ; 11 ,. ,«. ,. ^ *. -rTj.*:-'-' M. 1 ::r ::--;i;i ];;:i:i';,- is gCiUTauy ,") Ti. iiiaiVi., liie .sjilii'- pulley 18 in. diam.. and are of contact 200 to 2.')0°. The tail-pulley is usually 2 ft. diam. Hnbber belting on the face of these pulleys TIIK l-I.OTATIdN l'R()CK> lediK'i's the slip, tlic'rt'l)y iimreasiiif,' the power-efficieiicv ami the life of the helt. The overflow from tiic C.ildeeott cones goes into one or more Dorr thiekenci-s, aeeoniing to reciuirements, the underflow from the thiekeners. as in other methods, hein? handled with flooded sucti.in- i'liinps. Att.iiipts to mix tiie underflow from the Dorr thiekener with pulp on the drainiufz-belt in order to convey lliem together to the pump have not so far i)roved sueeessful. For the eontrol of the undi-rflow frnni Dorr thick'-'j-ers the hv:lr.".;:i:.(-aT- ;-.-..-.! !..-..! /.i _;i : in 'Hand Mctallurgieal Praetiee') has proved quite satisfactory, "a ronstant pulp, with Hrokoi Hill slime of 50% solid being ea.sily |il-.|'i)SAl. OK KLUTATIMN KK^IDrK iiiaiiitaiiu'd. This iiietlioil is coiisido red a good one, hi'i^ausc the <'()st of lal)or is h)\v, the life of tlie draiiiiiig-belt is prolonged, anil the tost of inaintenanee is small. Aiieriuate head-room is. liowevcr. neeessary for tiie erection of the cones; in some eases elevation is essential. A disadvantage is that a stoppage of the dump-iielts causes a stoppage of tiic whole plant. CoMBiNATio.N OF Classifikks AND TuicKKNKifs. Tills method has not. to my knowledge, yet been adopted at any plant in Australia, but the great success that it has achie'-ed at cyanide plants in America shows that it rould be applied to the handling of tailing and slime products at Broken Hill. The usual type of Dorr classifier, however, would have to lie especially lengthened to cause e.xtra draining of the sand product. Owing to the regular working of these machines the usual draining-belt may be discarded. At the .same time very little head-rooin would be required. This method is illustrated in Fig. 53. which shows the classiliers delivering din rt onto the inclined belt. It has, however, the same di.satlvantage as the method last mentioned, in tiiat it does not make the trcatuicnt- plant independent of the dump-belt stoppages. The cost of ei tion and maintenance would, however, be small. IlAxm.i.NO OF Drained I'lioDicTs. Tailing may lie handled in the following ways: (a) Inclined conveyor-belts and boom-stackers, (b) aerial trams, (c) tnieking. and (d) sluicing. In'cmnei) Conveyou-Rf.it.s and Room-Stackers. The usual angle for an inclined conveyor is 20 ; where possible the conveyor sliould be driven from the head-end. Where the head-end is high above the ground, the drive shoidd be either from the tail-end or from ,i large centre-i)ulley. midway along the belt, having a sinili-pnlley at each side above it, the ceiitrc-pidley being to 8 ft. diam. and resting, preferably, on a concrete base. The inclined conveyor is first of all built on trestles at the angle required. As the size of the dump increases, the conveyor is •■.xtended in the form of a cantilever, held bv guy-ropes from the upright trestles in the dump. A belt to handle 40 to 50 tons per hour would require to be one of 24 in. six-ply rubber Iniilt on 3 to 10-in. .stringers, placed .1-ft. centres. If driven from the head-end. the driving pulley should be 5 ft. diam. gear-driven, the tail-pulley being 2 ft. diameter. The AuF.trHlian r^r'ictiee is to use .*5/^*^firMt" ?";il!;-- .; :*Tiil tr.-.:-jrt-.;T-~ idlers instead of a combination idler. This practice is simple; the idlers enn be more easily lubricated. The best size of roller is 4 in. 2Mi iiii; ii.o'rviiiiN liioci:: diain. Jt is usually iiuult,' of stt'cl pipe shiuiik onto cast-iron i-nil pieces. A favorite practice is to have idlers and dead-eyes on the top of the same striufiers. the loaded and return belt running on rollers supported by the same, and liejnj,' ai)out three inches apart. The toj) rollers are usually spaced 4 to (J ft. centres, the return idlers being S[),iced at twice this distance apart. Wooden rollers for fast belts of this tyi)e are not satisfactory. In ealcul.'Miig the power required for this type of belt it is well Disi'osAi, (IK h'i,(rr\rii).\ ni>ii)rK 257 to rtMiitMiilxT that tlie liorsrpowcr lost in friction per !0(l It. varies iiivcrst'ly as the Icngtli of tiic belt, avcniffiiiK from 2 to ti lip. per 100 ft. A tifihteiiiiis arraiiKi'ineiit is usually fixed on the tail-i)uUey of this type of l)flt to cause it t.) run true and take up any unneces- sary slack. When an inclined conveyor luus heen carried out to an eeonomical distance, the tailing at its end is made into a hed for a hooin-stacker. This is an iron pole, which is held in position by four strong guy-ropes. Attiiclied to the pole is an iron lattice-girder, which is supi^irted similar to a oanliliver hy guy-ropes attached to the pole itself. This hooin stacker resis on a steel ball in a cup- shaped receiving device, which enables it to swing around as desired. Tlie weight of the boom-stacker is spread over a large .irea by means of a number of heavy timbers resting in the prepared foundation on the dum(). The conveyor on the boom-stacker is driven by a motor fixed liehind the boom, and traveling around with it. [The ]iliotograph (F^ig. 4!t) shows a good boom-stacker at Kalgoorlie. Western Australia, from which place th(> Hroken Hill system was largely copied. — Editor.] Akki.vi, Tk.\.\is. These are so well known that they need no description here. For moderate tonnage they are seldom used, as a bin is required and two men loading and operating trucks. Handling ok Slimk. The pulp from Dorr thickeners is either transferred by flooded-sucticm centrifugal pumps or three-throw l)umps, or else elevated by an ordinary belt-elevator. Where there is room for a slime-dam cloS(> to the treatment-plant, the belt-elevator, which is a very economical system of elevation, may be used. In other eases centrifugal pumps are resorted to. The thickened pulp may also be delivered to dams or sprayed onto the surface of sand- dumps. To remove the drained water it is preferable to u»» a wooden box-launder. This consists of two box-launders eonnected in the form of a right angle, and fi.xed in position at the starting of the building of the dam. The horizontal portion of the launder is laid 12 ft. inside the dam, and is carried to the water-sump outside it. The vertical portion passes through the slime and is bored with holes, which are plugged from the bottom upward as the building of the dam proceeds. Probably the best method of handling slime pulp is to pump it through a nozzle onto the surface of sand-dumps. By such means it may be sprayed evenly all ovt r tne •luiup. ^lis itiirs away witij (.i^Tiii ciUTKo ii:c 1 rising from the sand-dump. The idea was first originated in South Africa, and has onlv latelv l>een introduced into Australia. 2ris Tin; Ki,iir\Ti()\ I'nocKss THE ELECTRICAL THEORY OF FLOTATION-II By Thomas M. Bains, Jr. (From the .Viiting anil Srirntiftc Pnss of December 11. lai:,) TIk' article in tlif MiniiKj and Scuntific Press of October 23, inio, hy Mr. (), C. HiiNt„M, liMs lirnu^'lit out inaiiy jx.iiils of interest.' It .seem.s to me, liouev. r. that the fundamental prineiples of flotation ran best he stndi.^d witli hirjier particles, thus avoiding; the interesting. Init also little undestood 'eolhud' ehemistry. In jjravily separation l»y rising currents of water, Rittinger's formula V^c\': i^Z) liol.l'- true for i)artirl,.s above a certain size, naiuelv, about O.L' iinn for (piart/, and O.VA mm. in case of galena. Below the.s,. sizes. colloidal and other little-known phenomena become of importance and comi.liiate the investigation. So it is with flotation. In the laboratory, it is pn.ssible to use larger particles. The following experiments were conducted in the Case School of Applied Science on material sized through 20 and ;jO-me.sb screens. The phenomena connected with ]>r.>ferential flotation furnish new eviilence to strengthen the electrical theory. The simplest experiment, demonstrating preferential flotation, nuiv be performed as follows: Upon a 4-incli wateh-gbuss. place a little galena, blende, and quariz. of 20 to ;50-me.sb size. Add dilute „it,ie acid and place the gla.s.s under a mi.sero.scope. The acid attacks the galena, fitrming bubbles of II_,S gas that adhere to the galena. The particles of galena are electrified also, as can be seen by the actions of the pariicl.'s. The bleulo and quariz are not attacked. If the ore had been finely pulverized and dilute nitric acid added, the bubbles of IIS would have been sutificient to float the galena, leaving the blende and quartz at the bottom. However, with fine particles, some blende and quariz woulu have been entrapped, brought to the surface, and held there by surface tension. The bubbles are not sulTicient to float the coar.se galena, bn^ by a vanning motion of the gla.s.s. the galena will collect, being brought an.l held together by the II.,S bubbles, forming a mat, which =s lighter than rpiariz or blende and can, therefore, be painied of?', leaving the blende and qnartz. This experiment seems to show Miat the H.S is charged oppositely to the galena. i: rr.orc . oi,, oiitiHi. .i luini; acid iia i been added to the ore, the blende would have been attacked an.l the process would have been revei-sed, the blende forming the mat while galena and quartz Tin; KI.KCTKICAI. TllKOKY OK KIAJTATION — II 25!) "fie left lieliiiid. If dilute sulphuric acid, one part of acid to four of water, had been used, then both the l)le!idc and galena would have been attacked and if the ore had been finely pulverized, no 'preferential' wparatiou would have resulted, both galena and blende lindiiit; their way into the float concentrate. However, with coarse material, the blende is much more highly charged than the galtr.a and if the watcii gla.ss be tapjied ami the contents given a vanning motion, the blende will gather most of the ILS bubbles and finally float, leaving galena and ([uartz behind. This shows that the elee- trilication of minerals varies with different acids and also with different strengths of the sjime. This action of one mineral, 'robbing' liic otiii'is of ihcir bubb!(s. has not I n utilized in practice, as yet, but there is no reason why 'preferential' separations could not be made on a large scale, utilizing this principle. Less air or gas would be necessary than in the present type of frothing-cells and a clean concentrate would be produced at ofice. A separati.m of blende, galena, pyrite. and quartz may be made as follows; Add dilute sulphurc acid and pan off the blende; then add dilute nitric acid and pan off the galena; then add concentrated sulphuric or nitric acid, which attacks the pyrite so that it may be panned off. Or the separation may be made with nitric acid alone, varying the strengths; with sulphuric acid, by use of the 'robbing' action described above or by use of hydrochloric and other reagents that attack one or another of the minerals more strongly than the others. If galena or blende and magnetite be treated with dilute sulphuric acid, the magnetite will not be acted upon by the acid, but some of the n._,S bubbles generated by the sulphide will attach themselves to the magnetite, provided the bubble is formed near the magnetite. This illustrates the fact that eVctrical conductors in a conducting liquid attract electrified bubbles. A slight jar, however, will displace these bubbles; or a piece of sulphide in close proximity will rob the magnetite of the bubble, magnetite being a poor conductor. Referring U) the article on page 668 of the Mining and Scientific Press of October -SO, 1015, describing a patent for preferential flotation of blende, galena, and pyrite, the second paragraph reads: "The new process consists of treating ores in a medium (». e. sulphuric acid and sodium sulphite) that wets the zinc sulphide and which does not wet the lead sulphide or pyrite." This phenomenon brings out liiiciv tnc pari; piayiCi in noTatioii Dy tiie "" Jieit-otiic iiim. ' VV iien thio-sulphates, sulphites, or bi-sulphites are acted upon by sulphurii- aci add aiwl sodiiirii snlpliidc : ;^ms 4- I'lis f L>ir,s(),r..znSo, + im.so, + l>h,s •Xa,S()^ -f- ir,S(). -.- Na.SO. + II,,() + SO, " ;2H_S + S()_,^.2IL() f-;iS 'I'liis .sulplnir tlms fonii.d is in a vory tine staff iuid ads as a di.'l.M.tric film about flic (?al."im. for which if l,a.s a nrvnt attraction. Therefore, no frofhinp a(j, iit is nccd.'d in this case, as tiie dieh-ctric til 1 al.onf the hiihhles is formed l,y the sulphur similarly to the films of oil formed in the ordinary flotation processes. In' the last paragraph of the ahove-menfioncd arfi.d.' on 'Preferential Flotation.' the .statement is made that "the procuring of the efTect aimed at. is dependent upon the presen-e of a frothinj; anenf. onl,/ when a reducing „,,s is intro,taMce introduced," no frothing agent need be ised. This action nuiy be nicely illustrated by faking 20 to ;JO-mesh galena aniiiues less iiigtily ciuirged, and if sutticient bubbles are collected, the ma.s.« of bubbles and sulphide will float. If not sufficiently buoyed, the mass remains submerged, but it is lighter than the other sulphides .>«2 TIIK KI.OI'ATION I'KOCKSS or KaiiKiif innicrals and ran !»• paiiii.'d .iff or Sfparutod hy liydraidic c'lassitication. Till' .si'fomi point (if iiitcr.sf is llic formation of a frothing a^f.-nt, uitliin till' [ndf, when reactions take plan' thai liherate (iiolei;trif siilistanns in a very fine state, flcctrically diarjrod. The third point is tliat hihoratory rxpcrinicnts may not work out in i)ra('ti(:(', duo to failure to understand the nature of the eleetrieal charKes of the liuhl.les. dieleetrie.s, and particles of ore. A little stroiijfer reagent or a different way of frietionally ele('trifyinn the l.iilihles and pulp, or too tliiek a film of dieleetric or frothing assent causes the altraction to cease or change. It is no wonder that UTcat ditTicuIty has lieen experienced in the practical application "•' flotation t -es. wjien such delicate electric forces have to !«> considered. '-'J KKKKirr.S OK SUM HI, K CUM CDS K.VIS oK OKK ON H.(>T\T|i>N •nv.\ EFFECTS OF SOLUBLE COMPONENTS OF ORE ON FLOTATION By ■ N Occasional Cokkespondent (From the Mm. j and Snrnlifl,' I'r.ss of December IK. liti&i III concentration by rtolalion, tin- s..liil,K: components of an ore may play an important .-ole. Occasionally ores that are shown by preliminary test to be unsuitable for flotation may be treated by the process after the soluble ingrediei. have been removed by decan- tation. On the other hand, e.xcellent results may be obtained on certain ores by flotation in fresh water; but when the water is fouled by successive contact with fresh lots of ore (as is often the ea.SH m mill-practicej the results may be far from satisfactory. This article deals with a determination of the fouling agents m a cerUin ore, and outlines methods for overcoming such fouling efforts. Since all tests were made on ore from a single mine, the results cannot l)e regarded as generally applicable; however, it is hoped that the experience recorded here may be of some interest to others studying similar problems in flotation. The tests were made on a silicificd-rhyolite ore assaying silver 37 oz., gold 0.15 oz., lead 1%. copper 0.25%, and zinc 1.5%. The principal minerals were argentiferous sphalerite, argentiferous galena, and stromeyerite. The value lay almost entirely in silver. For this reason, only silver assays are here recorded. Suflficicnt analyses were made to indicate that the concentration of zinc, lead, "and copper roughly paralleled that of silver. Preparatory to making the tests, a large general sample of ore was ground to pass a 200-mesh screen, and thoroughly mixed. In each test, a 200-gram portion of the general sample was emulsified with one litre of water and 0.05% of crude pine-oil. The mixture was then treated for a half-hour in an experiment^il flotation machine, consisting of an agitation-chamber connected in such a manner with a concent rate-.separation chamber, as to permit of repeated treatment of the tailing. Kesults in a flotation plant treating this ore roughly checked the work in the experimental machine. Preliminary tests showed that when the ore was treated by flotation in fresh w.ater. thp tniiirii? saa"vA.-; n .-.- .-.! j iJ- concentrate assayed 440 oz. per ton. When the water used in the first test was removed by filtration and re-used on a second test, the tailing assayed 18. oz., and the concentrate 240 oz. When the 264 TIIK II.OTATIO.V I'muKSS satnc Wiitcr was re-iis<.i a iliinl time on a fivsli saiiii)lf of or.', tlif failing' assay.'.l 27 oz. ; tlie conceiitratf, 1!»() o/. Kvi,lriitly sonic fxtiviucly (IcIftiTious siilistaiices had been dissolved t'rom tl re. An analysis was ..lade of tiio water filtered from llie tliinl test, uitii the following results: Iron (ferric) y.^. Iron ( lerrous I 00"' ' Aluminum -r- 1 r. Caliiiini v-i. Magnesium oxide 01'" ' Sulphur O.02o4 Manganese !o!o01% Potassium and sodium ,1 oiO'; Copper ^i. Most of the soluble miiierals were present as sulphates. The next step was to delerinine the effeet, on flotation, of the various sul[)hates. Sodium and potassium suli)liati'S. when added to fnsh tests in the proj)ortion iiidieated in the analyses, yielded a 1;{ o/. tailint; and a (i;)0 oz. eoneentrate: thus producing' a marked inerease in tin' <.'rade of eoneentratf without detrimental .ffect on the tailing'. Manganese, magnesium, and ferric sulphates produced no effect when added in tlic proportions indicated; in larger amounts, mag- nesium .suli)hate was lia.mfiii and ferric sidi)hate beneficial. Ferrous snlpliatc proved extremely injurious to flotation. When present as abovi' recorded, a 20 oz. tailing and a 240 oz. I'onccntrate were produced. When a small amount of copper sulphate was added to the same (piantity of ferrous sulpliate. the tailing a.ssayed 2.") oz.. and tile concentrate 200 oz. Evidently ferrous aii.l copper suli)liates were the prinei])al fouling agents in the original tests. It was neces.sai'v to devi.se means for correcting the etVects of Miese sulfiliates. First : sutiMcient sulphurie acid and hydrogen peroxide were added to a ciiarge containing ferrous sulphate to I'onvcrt the ferrous sulpliate to the ferric state. The tailing from this eliarge as.sayed 11 oz., and the concentrate SOO oz, With the sa,.,. amount of acid, but using no i)ero\ide, the tailing a.s.sayed 14 oz., and the concent rate 7S0 oz. Evidently the acid increased the grade of concentrate and also decreased the injurious eirectsof the ferrous sulphate upon extraction. Second: efforts were made to precipitate the ferrous and copper sulphate. A test, containing these sulphates in the proportions indiciited ill the analysis, was rendered slightly alkaline bv the LKKKCTs OK SOMHI.K COM I'ONKNTS OK o|(K ON KI.OTATION •2fi.1 iulditinii of liiri,. Iivilrale. Tlie tailing assayed 12 oz., auii the loiiicntratc 4')!) oz. Wlicii .sDilium liydrate was ust-il in place of liiiif. tiiu tailin-; a.ssavfd ,s oz., and the com-entrate (300 oz. With the iron preeipitatcd hy sodium carhonatc, the tailing assayed 6 oz., and I he .-oncentrate SOO oz. With a comliination of lime hydrate and sodium earhonate, Ihc concnitrato assayed 800 oz., and the tailing ■ '• oz. Evidently the use of hydrates and earhonates prodwees nmch better irsults than ean he secured hy acid. The eost of sodium hydrate and sodium earhonate. and the injurious efTeets of the latter upon settling and filtration, restricts the use of these eheinieals. Lime hydrate, on the other hand, i»resents a cheap and efficient means for preventing the aci-umulation of ferrous sulphate in ndll- shate resulting from the reaction is somewhat defriinental tn flotation; a saturated .solution yielding a Ifi oz. tailing and a 4r>() z. concentrate. In ordinary practice the solution would he far f r. m saturated, and the results much more satisfaetory. The lime hydrate method has heen successfully used on this ore III roiitiiuious mill-tests. During flotation tin- alkalinity was main- tained as nearly as possible at 0.02 Ih. lime-oxide i)er ton of water. After tlofafion, half the circuit-water was wasted, the remaining half heiufj su])plemented hy fresh water, at the head of the mill; lime sulphate thus being j)revented from accumulating in the .solution. For a month during which the process was used, the '•oncentrate from the flotation plant averaged HOO oz., and the tailing ti oz. This compares favorably wiih a 20-oz. tailing from gravity .oncenf ration and a 12 oz. tailing from flotation in an acid solution. Aside from eff"ecting better concentration, tin' lime method is cheaper than the acid process and is not injurious to subsequent cyanidatioii. When lim- is used in flotation, extreme care must be exercised in maintaining the proper alkalinity. The table submitted herewith shows that the best restdt.s, both a.s regards extraction and grade of concentrate, are seciirerl when the alkalinity during flotation is extremely low (between O.Ol and 0.02 lb. CaO per ton of solution). Experiments indicate that alkalinity is beneficial to flotation but that the coagulating effect of high lime ujion slime increas«>s the affinity of the slime for the froth, lowering the grade of concen- trate. When the coagulating eff"ect is counteracted by the addition of sodium carbonate, or wlien sodium hydrate is used in place of lime, an alkalinity equivalent to a half-pound of CaO per ton of solution may be maintain d without harmful efTccts on flotation. •Jtiti rilK Kl.y emitloyinj: hydroi;en sulphide in a solution renilcred alkaline' hy lime hydrate, a tj oz. tailing and a -i'tO oz. concentrate were olitained. Wlieii sodium sulphide and .sodium hydrate were used. tlie tailing-assay was reduced to 3 oz.. and the oonecntrate increased to 7(1(1 oz. These results show that the injurious etTect of soluhle eoppcr may he overci'iue hy the use of hydrogen or sodium sulphide ill conjunction with lime or sodium hydrate. The foijiiwing comdusioiis were estahlished f(U' the ore tested: 1. Sddium. jiotassium. and ferric sulphates are rather lieneticial to flotation than otherwise. 2. -Manganese sulphate has jiractically no etl'ect ( 'i tlotation. .'!. Magnesium and caleium sulphates are slightly harmful, while ferrous and cojiper suli>liate are e.xlremely harmful. 4. The effect of magnesium and calcium sulphates may lie "vei-- eoiue by the use of sodium carhoiiatc in an alkaline solution. 5. The effect of ferrous sulphate ■•an be owrcome by the use of sulphuric aciii or. better still, by enii)l.;y!ng (luicklime. caustic soda, or sodium carbonate. ti. The effect of cnp|)er sulphate may be overcome l)y the use of hydrogen sulphide or sodium sulphide in an alkaline solution. 7. The use of sodium carbonate, though aiding materially in flotation, is of doulitful utility in plants where the iialj) must be dewafered. H. I.ime liydrate is slightly less satisfactify mefallurgically than sodium hydrate or sodium carbonate, but the us- of it is iiie.\j)ensivc and aids maferiallv in settling and filtering. Kl-or ATION" — A I'ARAIX)X •2ti7 FLOTATION— A PARADOX By Dl'DLK.Y II. NOKKIS (From the Miniiuj and Srit'iitific Press of December 25, 1915) Flotation is a paradox. In a Howiiitr iiiixtui» of tiiu'ly pulvcriziMl ort' ami water it oaiisi'S the lieavy metallie sulphides to float to the surl'aee, where they are eoll,- -ted for further metallurgical treatment, while the light barren ganjrue sinks to tlie bottom and is run into the tailing-pond. Tills api)arent reversal of the attraction of gravitation is due to tiie introduction into the flowing niixt\ire of a snuill quantity of oil or other emollient in such a manner that every particle of the ore, whether metallic, or gangue. is brought into contact with the oil, whereupon there is what seems a selective actit)n between the oil and the metallic particles sudi that these becomi' coated with the oil, whereas there is no such action of the oil upon the gangue. Under proper conditions, at or about the same time tliat this oil coating of the metallic particles takes place, tiiere may be caused to appear in the flowing mixture bublilcs of air. These attach t.ieraselves to the oil-coated metallic particles and stick to tlu'm with more or less tenacity, making a new entity consisting of metallic particle, oil-coating, and air-bubnU . The specific gravity of this entity is less than that of the water of the flowing mixture; thercui)on. because of the attraction of gravitation, and not in spite of it, the heavy metallic sulphides float to ihe sur'^'-'e and the comparatively light ga;ignc sinks to the bottom, neither oil nor bubbles having any tendency to attach themselvis to the barren gangue. My interest in flotation arose from the aceumulatiiui at m- mine. the Magistral, at Zaeatecas, Mexico, of a couple of hundred tlioiisan; tliroii^ii the lahrir and when released and started on tlirjr npward jonrncy were of a nniforiu size, about tliat ol' a niarrow-lat pea. Witli y;riater i)ressure the si/e of tiie huhhles was reduced, but tiie action of the air was so violent that the mixture was like a boilinsr geyser and everythini;, ore and ganf^ue alike, was hronght to the surfaee. Thereafter my flotation experiments were suspended until one day in a Pullman ear i>n tile Mexiean Central railroad I drew some wafer into the hand wash-basin and I noticed that it was as white as milk, but presently became just ordinary transparent water. 1 saw at one that this was due to an artitieial aeration of the water in the tank under the ear. and when the train stoj)pe eastern shore of San Francisco Bay. I believed that T had discovered a basic principle in flotation, ami in September 190fi I applied for V. S. patents on the method KLOTAT'DN — A I' VU \IM)X 26!t ami nil the apparatus For usiiip tlu' Pullman hiitiMi'S in Hotatioii ; later I took out patents in ten foreign countries on the same i)asis. Continuing my nietallursieal investigation in the summer of l'K)7, I went to nearly all tiie principal eopper-eoneentrating mills in Coloratlo, I'tah, and Arizona, and to Caiianea. I saw all the stars of the first magnitude in the copper metallurgical firmament, hut they shed no light on flotation. In tact, I was asked how the word was s])elled. The not result was that I went hack to Zacatecas and later liuilt the Magistral smelter.* About this time I received word from my patent attorneys that 1 was opposed in the London patent-otfice hy the Minerals Separation; but I instnicted them not to appear and the case went on without me, as will be seen by the decision in the case where it is cited that "At the hearing Mr. Hallantyne ai)pcared for the opponents; the applicant was not represented." Notwitlistanding the fact that the opposition had things all their own way, ihe London patent-otfice over-ruled the o|)position and decided in favor of issuing ni' patent, and .vhen the Minerals Separati(ui appealed to tlie law-ol^icer *he decision wa.s affirmed, on February 24, 1010, and tne British patent duly issued to nic. In the recent case of Minerals Separation against .Miami, counsel for plaintiff .said tl'at the defendant interpreted the older patents, not in the light of the siate of the art at the time the respective patent was applied for, but in the light of later development.s. It so happens that a reference to the decision in Minerals Separation V. Norris before the Hritish patei ' authorities, shows that the Minerals Separation is now doing that very thing. My Hritish ai)i)lication was dated June 27, lltOT, and was opposed by flic Minerals Scjiaration on the grounds of prior Hritish |>a1en1s. as follows: No. 12T7ti A.l). 1905— Froment No. 20,2S:{ U»04— Elmore No. 7.S0:{ 1" '.") — Sulman No. 2B.712 I'.kC) — Sulman No. l:?,268 lf»07— Hoover These include the liritish ])atents corresponding to some of the American patents on tlie basis of which the Miner.als Separation sued Tlyde and Miami in the United Stat.'s courts, and the suits are now pending. The case in the Brit^h pjUentotfice was d 'cided. ;ind •See 'The Copper Handbook,' ini2, page 545, 270 TIIK H.()T\'nnN l'l(iH'h> till' (iccisidii lifiirs (iaic. .Miiich I."), lIKIil, ( 'iiiisc(|iiriiil.v llii' [xisilidii of till' .Miiictjils .Si'()!iriiti()ii as to the hasis ol' their patnu ri^'lits as stali'.l in the casi- a^'iiiiist iiic li.twtfii .(uiic L*7. l!M»7, and March 1,"), l!K):i, is the trill' statement of tlieir own idea of their ri^iits and l>(>siti(in and not tiiat wt iij) in the later eases some years after. and in the liglit of tiie more mature ('.\|)erienee whieji is ])roteste(l \ty .Minerals Separation itself wiieii used liy the Miami eompany. Here is the Minerals Sei)ai'alion position in the ease against Xorris, as a|)|)eai-s in the decision, which says that Mr. Hallantyne relied mainly on the Sniman and Hoover patents. lie contended that the nnderlyin'T idea of the various ]>roce.sses is as.seried in Claim No. 1 of tiip Sulman patent, that is. introdiicinfr hy some means or other air under pressure into |)uip contaitiinj,' oil and water and then allowing' the i)ulp to eonu' into a vessel which is open at the top to the atmosphere. Claim No. 1 o!' the .\merican Sulman jtatent "consists in mixin<; the powdered ore with water, adding a small proportion of an oily li(|uid haviiiR a i)referential affinity f(U- metalliferous matter (amounting to a fraction of 1% on the ore > agitating the mi.\ture until the oil-coated mineral nuitter forms into a froth and .separating the froth from the remainder l)y flotation."' There is no liiat in Mr. Ballantyne's presentation of his ca.se before the London patent- otllice that he or his client, the Minerals Separation, placed any importance ui)on the little plira.se in parenthesis (amounting to a fraction of 1',' on the (u-e) and it can hardly he imagined that any court would permit, at this late day. a siil)stitution of another idea for what Mr. Hallantyne claimed, in tlie ea.se against Norris. to he the underlying idea of the various processes. The decision, in my favor, contained these words: "It a|M)ears to me theri'fore. that the applicant is entitled to a patent for his invention****! decide therefore to seal a patent on the applica- tion***." The Minerals Separation ap))ealed. but the decision was .-inirmcd and the patent is.siied February 24. IHlfl. The Federal Circuit Co,\rt of Ap|>eals. on appeal, decided the Ilyi'e case against the Minerals Separation, in tlies(> words: "We hold that to sustain tlie appellee's patent would be to give to the owners thereof a monopoly of that which others had discovered. \Vhat they claim to lie the new and useful feature of their invention. ■ • st ' d by their eon ise!. is agitating the mixture to cause the oily-coated mineral to form a froth. As we have seen, that feature was charly anticipated by the prior art. and when the FIX)TATInN- 'AH \l><).\ 271 elt'iiicnfs of till' appellee's elaiins are read one liy one, it will be fouiiil that each step in their proeess is fully deserilied in iiion' than one (tf the patents of the prior art, with the single exception of the reduced quantity of oil which they use." The .iud^nient of the court l)elow wa.s reversed hy the Circuit Court of Appeals and a motion for a re-heariiig was defied. Then the Jlinerals Separation applied to the U. S. Supreme Court for a writ of certiorari, which was {^ranted, and the ease is now hefore that court. The Minerals Separation advertised that the Su])reme Court had pranted their petition, without going into details as to just what the petition was. As a matter of fact, the granting of a writ of certiorari hy the Supreme Court is in no sense a decision on the merits of the case. Prior to 1891 an appeal to the Supreme Court from a Circuit Court was a matter of course, if tlie sum involved reached $1()()(), the result being a crowded calendar, years behind. In 1891 the Judiciary Act abolished the Circuit Courts, merging their functions in the District (.'ourts, and creating the Circuit ( oui-ts of Appeals with final jurisdiction in many classes of eases, including patents. The Act provided for a writ of certiorari in ea.ses where the judg- ment of the Circuit Court of Appeals is final and the ndes of the SiiOreme Court say that the writ will issue where ea.ses of great gra 'ity or importance are i?ivolved or where two different Circuit ( on 'ts of Appeals have rendered conflicting decisions. The proceedings on the application are very technical. A petition must be presented setting forth the facts, of the case together with the reasons for the writ. Two weeks notice, or west of the Rocky Mountains, tlirt^e weeks, to the adversary; and no petition will be granted within a fixed time before the end of the term. With the petition must be filed a certified copy of the papers on winch the court below acted and 30 copies uncertified. No oral argument is allowed. As Chief Justice Fuller expressed it: "The inquiry upon the application is whether the matter is of sufficient importance in itself and sufficiently open to controversy to justify the writ." At the October term of 1914, at which the petition for the Minerals Separation writ was granted, there were 45 applications for writs of certiorari, of which 11 were granted and 34 denied. In the reports no reason is given for the Court's action in deciding petition for certiorari; but it is extremely probable that a certain number of the applications were denied because the trclmical require- ments of the rules were not observed. That is about the gist of :V: -'- TIIK KI.OTATluN I'UOCKSS tlif i)rcsfiit stale of the lly.lc I'iisc TIiitt has Im'.^ii no ])ar(loii nor coninuitation nor rcvci-siil. lint nuTcly a stay of .xfcnlion. Thf MiniTHls Separation also advertised tliat tliey ha. .\])pcals lieintr so stronuly against them, tlic inference is irresistihie that however little these waifs and strays of patents were houirht for, they w.-re not worth it. One lan understand the keen regret on the part of tle^ .Minerals Separation that their Froiuent pi ess had not heeii patenteil in this .•ouiitry, hut only in Italy and KiiKland. They started with the Catterniole ])roces.s. which was not a succcs.s, and aci|uircd the Froment afterward. The Cattermole, usiiif; 4 to (>'; of oil. was an iiii|u-((venit on the KImore, which used nuue. They accpiircd the Froment. which was a bulilile i)rocess as apainst the i>roci'ss.s usini; only oil. and then lie<;an a new series of American applications for patents. The attempts of the Minerals Separation to jrct a foothold in this country for their process of flotation hy ■■a<;itation to lorm a froth" hetrin with >s:ir).12() Siilman r llie induslry from this toll and also from extravajrant prices for |patented machuiery. Tlie sii-}r,,s,i„„ |,;,s recently hec, made that one of the most Heeled thinjrs in the mineral industry at the pn^s^Mit tim.. is .s.mie easy way of makinsr flotation tests at the mine; so that a mill. foreman ">• Miine-l,oss may he ai,h. to make his tests on his ores and .lecde whether or not they are su.sceptihlc to flotation an.l then .hsit;!. a l-nn.e.ss for I real in- ihcm. Of ,.o,irse, any a.vom|.lisliments llmt a Inreman .,r min,. I,n.s,s may have, add to his value: and ahility to s't a hrokeii let; or cure a ease ,,f mountain f,.ver mitrlit earn for hirn an additional salary, hut ashle from lii-sf aid' to the iniured no one would want to put him.s..lf in the hands „f tlu- foreman' or the und.rsrroniid min,.d,oss for medical treat nt. It is the .sain.' way with tests on flotation. Aside from mere preliminary experi- nu'iits, testiiiff oivs for flotation is as miK'li a separately protVssional iMatter ,is eanntr for a t.rokeii leg "r a ease of mountain fever .MetallllI•^'ical ennineorinp is now so far advanced that tli.'rc is hut small rea.son for goiuf? astray in the matter of treatment of ores hy t|..t,iii,,ii, provid,.,! ade(piate preliminary tests are made hv expert nh'tallurtrical entrineers. The cost of .such tests is triHin- and their importance and value not to he exa^'f,'erated. One threat rea.son why a mere practical niillman or miner cannot devise a process from the patent claims and specilications is that mo.st of the imi)ortant cleinent.s of the actual installati.m are omitted from the j.atent. The e.s.sential principle of the patent of Klijus Howe for the sewiii}? ma.'hine wa.s that the eye was in the point of the needle. Taking that for a starter, how far would a iium get toward huilding a modern Singer from the Ilowe patent? It is like an e.iuation in calculus. Take such an equation representing a mechanical movement ami com])are it with another equation of the :^7^»irl3C/St, KT,OT\Tln\ — \ I'VKMMiX path n( !, ...Hii.'t. l)iir.T,.|itial.. both ;,M.l „ul >fo tl iisiaiil laiiMPs ami III,, ilitr.ivritial .Miiialioiis ini^'ht hr i,|..iili,al iii Ion,, Ur int,.^rat,. lli.iM. I)u y,.u K'-'t l)a,.k y.Mir iiKMhatiK^al iii,.v,ii„.|it an,! y,,iir r„i,wl\ orliit .' V,iu ,1,, iMil. Viiiir iDiistaiit lailiirs ,1,. nol iv appear. TIh' sjirnc way wilii palnit sp.vitirali.iiis aixl clainin. Tlwy c.Mtaiii only ""' 'lifffi-i'iitials. Ill ia.t, a i.-.>.nl I.-II.t iVoni the I'at.Mil-l )lli,"c sJiiil: --It IS .sii^'Ki.st,.,! that tli.^ .iaiiiis •■liiiiiiiat,. all iiiiiu.c,..s.sarv ivIVrciiiMs t,i slniclun' ami thai llu^y Ur liiiiit.M i.. ih.^ a.^tiial pnu-.^ss St, •[IS. " Hy a pr.ip.r coiiihinatinii ,if iiihivsls, ii,,t ,,ii|y ,.aii tlnrc tu- av„i,l,.,| tj„. |,ayi,i,.|it ,.1' n.yalli.s ,.i, „ivs trvahd an, I hi^rli ])ri,-..s I'-ir pal,.|il,,l iiiacliiiicry : an, I ii„t only ••aii ,v,Ty iiiill-,,\Mi,.r he asMiri',! of th,. .•oiislant liitfli cnicu.n.-y ,.f his plant, hut h.^ ,.a,i 1,,. protc'tcl H^fainst intViiiKiiiK' pah^nts, an, I if sii,,l f„r iiirriiiu,.|n.nt he I'an Im. ,1, r,ii,l,.,| at a tiiHintr cist t„ liiiii.s,.|f. a ".ninral fund lieinn pi-(,viil,,l. al a .small pctvcntai.',' ,,1" what tli-^ ns ' ihc .MiiuTals Scparaliiin i)al,.|il w,.iil,| .usi him 'rj,,. way t,, ,|„ is t,. pcrlVct a pnicfss in a imtallurs.'i,-al lali,.rat,,ry to tit th,. sp,,-ial iifc in ca,'!! ease. Wli,.n ih,' pnic'ss is p,Tf,Mi,,l cart' must ho takfii that it iiiclu(l,.s til,, pat, Mil pi-in,-ip|,. uiKhr wlii,.|i it is t„ h,. Ii,-,.nsi.,l and docs nol iiifiiiif:,. any .itli.T jiatfiit. In on,. iiiin,> in th,. Xintli ('mint uhcrc a li,)m,. nunli. |)fo,-(.:s has hci.ti pali-h,.,! uj), it sc.ms as thoiitih cvi.ry wvll kii,,uii Holatioii pat.'tit has 1 n infniif;,.,l. and yi'l th,. proc'.ss will n,it work as it ouKlit. Wt.JI. siijipos,. th,. pr»le their ease. l{ut tii,.ir eaw would not be favorable. The first thinp that th.-y would meet woidd |„> a certified copy of th(. proeoedings in their own eountry wiiere tlieir own (Jovc.riiment decided that the N,)riis process, irithounh the appli(.aiit was not rcpreseiite.l at the hearing, was not an infringe- ment of the five patents governing the Fromeiit. the KImore. or the Minerals Separation processes res|)ectiv,.|y. The Jlinerals Separation people were so sure of their strat,.gic position, so confident that their American patents would o,. sustaiired by the c,)urts that, from what sc,.ms mere want,inn,.ss, conditions were imposed upon the licensees that were intolerabl,. ; with the result '■-•I = V .i ..-r' . '*■.-< %^.^ '^r^^^ -1.'^, r^i'-*.^' MICROCOPY RESOLUTION TEST CHART ANSI ot^d ISO lESI CHART No 2 1.0 I.I 1^ 1^ I: y£ 112.5 2.2 20 ill 1.8 1:25 III 1.4 mil 1.6 ^Fl 't--'- t.ji;' Mi;i- -i-ee- ' '16} *82 - 0300 - Phone ^S "fiJ 288 - 5989 - Fa» 276 Tin: .'I.OTATION I'liOC'KSS of ,1 concerted movement on tlif part of the whole niiniii future. ClIAS. RfTTKIiS. San Franci.sco. Decemher 1:{. TESTING ORES FOR THE KI.oTATKl.V I'lJOCESS 277 TESTING ORES FOR THE FLOTATION PROCESS By 0. C. Ralston and Glexx L. Ai.lex (From the Mining and Scienlific Press of January 1, 1916) lNTH0DicTi,,N. *Altli-ugl, tile suhjrrt of testin- l\.r Hotatiou lias hwi, wdl presfiite,! in T. J. Iloovei-'s hook on ■Con.-cnfrating Ores by Flotation,' there is need of later infon.iation on tiiis timely subjeet. Mueh testing has been done in laborat: ries not eonneeted m any way with the Minerals Separation eonipa-iy. with whch Mr. Iloovvr was formerly iiss machine and froth, goes far toward bringing I he beginner to a p(,int where he can test efliciently. •By iierniission of the Director, IT. S Hnreau of Mines. Comn'unicated by I). A. Lyon, metallurRist in charge of the Salt Lalie station of tl.o v s uureuj of Alines, co-oppratinR with the University of Utah. O C Ralston Assistant .Metallur-iat of U. S. Bureau of Mines, and Glen L. Allen, Research Fellow of the University of Utah. 278 TIIK KI.UT \'ri(lN I'HilCKSS X( <\' tin lit enituii' iiicntiiins tlic n tlijit it is (lilliiMill t(i fift a lii^'li pcmMitafrc of extract ion and a lii<;li frradc i)t' Hotati (iiK-fiiti'atc at tlic same linn •Ii(> 1 botil of tlii'sc tl ic^rimicr (it'tcii strives after i!ni.'s in a siii^He test, uiiereas lie slicnilil deteri aeli eaii he atti'iiied betore he attempts to (ihtaiii hoti taiiodusly. Fiirth to give as trond result )re, it is (litHeult t s as a larjre one. i So the small maeli o iiiani|)iilate a small iiuieliiiie inti: aftei' eonsi(|ei-ahle i)raetice. me is jrenerall.v pes,simislie. eom|iared with tli larfjie one. It is jiraetieally essential for the bej^iimer lo \veij;li and Feed Concentrate Tailinof- Flu. 54. TUK M.Mgl ISTKN Tl a,s,say all of his iirodiicts in order to .see if the e.xtraetion and the grade of eoneentrate are satisfactory, where an experienced manipu- lator can often tell t>y aid en set aside. The Wood niaehine can be built in miniature and for several years a small niaehine of the type sketched has been used in the plant of the Wood ore-testing works at Denver.^ This small maeliine was about two feet long and one foot wide. The method of operation is the same as that of the full-si;;ed machine. (See P'ig. 5').) As neither of these niaehines has been inueh used in practice, they are merely mentioned 'or the sake of completeness. Hoover'' lias recommended a test on a vaniiing-plaque, so that tin' sulphides will float ort* onto the surface of the water, but we consider this test of practically no value. Hoover, however, acknowledges that it is merely a test illustrative of the film processes. In testing ores for the Potter or the Delprat processes. Hoover's text is again the source of infonnation. An illustrative test-tube experiment is pictured in Fig. 56. Tubes containing 3% ILSO, or acid salt-cake stilutions and a little sulphide ore are warmed nearly to the boiling temperature. Bubbles of CO., attach themselves t. the sul- phides, travel to the surface of the solution, i|i;li a stiitliii'i-liox in the liotloMi of the iiiaehiiie. Tile Idwer iiiipeliei' with four vertical vanes is suhiiier^'ed ; it aiiitates and eiiinlsilies the pulp while the upper inipeller, likewise witii four vi'rtieal vanes, aets as a puiiii) to lift the pul|) and heat air into it. A iiuiiey and ))eit conneets the shafting; with a variahlc-speed motor. A donie-sliaped lid is used on the iiiaehine. A small hole in the to|) of the dome allows the introduetion of oil. acid, water, or other matei-ials without the removal of the lid. The lid is so eonstrueted that it ean lie turned upside-down with the dome Wooden Pao/a/e Froth. Fi(i. I'OTTKR-DKI.rR.vr TKsr. oxlendiiifj down into the froth-hox. and in this position it ean aet as a fuiniel. The dome rests then on the top of the agitatioii- eomparlment and no froth ean eseaj)e into the frothdjox. This allows a period of a spitzkaston. where the froth ean lie removed. A disrharKe-i)luiar at the bottom of the machine allows the flushing out of tailiritr after the test has been eompleti'd. So careful has been the desifjii of this test-machine thai even this discharKe-plu. This tends to allow mort> of the TKSTINC iiKKS liiK TIIK l-lnTATIoN I'HOCKSS 2s:i f'titraiiicd >jr;iiitriii' to srtile dul of tln' iiiiinTiil t'lutli. 'I'lii' siili's nt' the sj)itzkiisti'ri ;irr of liciivy iihiti'-trliiss. cai-li fiistiiicil to a iiictal frame liy nieaiis of screws Tlic w niiis,'lit-iroii slint't projerts tliroui;li a t>rass stnrti.it,'-lio\ ninl is Miiiporteil liy a hall-lieii! ini; lieiicatli. All the other metal parts are of east ahiiiiiiiiiiii. The small virialile-speeij itiotor mav he of cither I). C. or A. C. Fic. 3S. riiK.i.vNMV .\IA(m.^^:. < ov kk i.wKiiiKii. type. F. a. Jaiiney reconniieiuls the ti.ie of a (jieueral Electric. »iiutiL-»\ iiist'iicd position. (iSee t'ig. j)8. i This is done to allow thorough mixing without circulation of the pulp. All or part of the oil and other reagents are now added '2tHi Tin: Kl.uTVIIi'N I'HOCKSS "I"' 'll'' lllntnr l,r,,ut;lll up t,, full S|».,..i f.,I- .id .s,.,.,„i,ls. Tli,. sp,r>\ IS ;it,Mlll low. |V,| In III,. MlillilllllMl iuul ill VIT is tUril.-,! .,V(T into IK iipn-lil ,,nMii„„. .s,.,. iMtr. .-,!!., Tl„. s|».,.,| ,.. il„.n n,js,.,| ainl "■"'■'■ '"^ '"''l"'l 'l"(ini,'li tlir liul,' in 111,. t„|, ,,r i|„. |„| nnlil il,r frntli HI thr .s|Ml/k,isl..n is nnirly at tl vcrHow lip. Tin' ultiinat.. sj I "I" til,, airitiil,,!- uill ,|,.p,.n,| s„ni,.\vliat iipi.n tli,- ,.|iara,.|,.|. ,,f this I'n.th, as .s,,ni,. , ils will iriv,. a ,|,.,.p p,.,.sist,.nt r,-,,tli. uhil,. ,,11,,.,. fn'llis ar,. linn and l.rilti,. aii,| all,i\v ,il' nioiv watiT ll,•ill^' a,l,l,.,i tn 111,, ma, ■Inn,., as u,.|l as more vini;,T tiin,. to alhiw th,. , -lit rain, .,1 -.'anj;!!,. t,, s,.ttl,. out of the froth lM.f,u'c it is (iis,.harj;i.,l from th,. nia,.liin,.. In su,.li rast.s it is h,st to h,,hl ha,.k the froth until its appoaraii,'.- sh,.ws it to )).. fairly ,.h.an. i{,.>:iniit.rs ar,' lik,.|y to ilijnt,. th,.ir froth with to,i iiiu,'h fzaiifriu-. In a larjrc- si/,.,1 ma, •hill,, th,. fr,iili ,-Mn trawl ,iv,.r from tour to ,.i- ruii 111 ii,,iii ., i,. :;,i minuies in sucii a maelmie with .'lOO trraiiis of ore in aiiythinjr from a 3:1 to a 5:1 pulp. The plass ides of TE8TIN0 ORES K'H! IIU; KI.oT \'l'ln.\ I'ljcicK^s 287 tilt' .s|)it/.kastcii iillT\TI(IN I'RorKSS eoiK't'iitrati's lUu- \o .ntrjiitiMiciit uf j.';ni^'iic. in tln' ri'iiKiviil of all tilt' iniiicral. The stutliiijr-liiix in the hotldin will proljably leak if not watched. Ilowcvfi'. this driving' of the iinprl'iTs from lifliiw. instead of from Vu,. i;:!. I III iHiiiv 1. It \i \i in\F, aliove, leaves llie top of tile iiiaeliiiie free for the operator and is more eoiiveiiient ill every way. This is of iiiipoHaiiee ill a laiioratorv- ,,,.,,.!,;.,., ..,,1 ...iiT ..-.,, .1 ,. ,. , ,». . . '*" ■■■-': ••■::; " •.■ :;r.:- :;;;■ :;:.;■ ,;: ;; \; iilTiii^'-iM iX. ill i*n Jie-seaie iiiaehiiies a slnflinir-liox underneath wonid not he tol. 'rated, and the TKSTIMi OKKS FOR TIIK FI,(lTATl(iN I'KOCKSS 289 drive should l)t' from ahovi'. We would iilso sugg»>st a siieet-Jead constniclion as hi'iiig more easily built. A J-inch sheet-lead is suffieicutly ri};id to stand )ip well, while it is duetile enough to he FlU. G4. TlIK HOdVKK \IA( MINK. SHOWING STIHKEK. A. Spltzkastt'n. H. Agitation compartnient. r. Variiible-speed motor, n HpliiiiiinL' linlts A', Impeller. F. Concent I ate disihargo 290 TilE FLOTATION PKOCKSS worked readily into tiie drsired siiape. The .j.n.its arr .a.sily hi.ni.Ml. aii'l it is auid-proof. TiiK IIoovEu .MAtiiiNi:, so-called, was desi^'iied after a test- iriachine deserilied in the second edition of Hoover's hook, heing copied from one of Ly.ster's patents, and has l)een imieh eoi)ied hy peoi)le wishing to make flotation tests. An improvement over this eonstriietion was published hy Kali)h Smith* recently (see Kif?. 61), and a modified sketch of the same is shown in Fip. fV2^ while I)hotographs of th.' machine used for a while in our lahoratorv are shown in Fi- 6:i and 64. Eith.-r a varial.le-speed ;notor is helt'ed to the pulley that drives the stirring mechanism, or a pair of cone- pulleys on a constant-speed motor is used. This construction has been popular because it eau be ?i)adc of wood, at small exi)ense. The Janney machine will cost aliout $100, while the Hoover machine can be built for a small fraction of that amount. :\rr. Hoover's original drawing does not show the spitzkiusten drawn to a point, as oidy the front side was beveled. Our sketch shows both sides beveled. This is desirable, as it eliminates space in which fine sand can settle, and tends to minimize the amount of pulp lying inactive in the spitxka.sten. In the agitation-compartment the jnilp is swirled into the corners, where it is well mi.xed with air: hence the baffles sketched in the Janney machine are unnecessary. One objection, however, is that uidess the agitation-compartment is very tall the pulp lieing swirled into the corners has a tendency to .si)lasli out, and a lid similar to the one on the Jaiuiey nuichine is desirable. However, it is difficult to attach one because the stirrer- shafting is in the way. The operation of this niacliine is practically the .same as that of tlu' Janney. e.xcept that without glass sides on the spitzkasten it is hard to get as clean a froth. A charge of 1000 to 2000 grams is necessary in this macliine. TiiK Si.iDK Machine, as shown in Fig. 65 and 66. was designed by Hoover and perfected by many others. In recent jiractice it is motor-driven. A number of these machines were given by James M. llych' to various universities in this country. Many peojtle favor ;liis apjiaratus for the reason that they have had little opportunity to use any otiier design. In this machine the agitator is driven from below thmiigh a slutruig-box. as in tlie Jainiey, with the consequent freedom of the top of the machine for the convenience of the operator. The top half of the niaclune is so constructed that it can be slid to one sii.li) eiittinrr <,fT tl.n f../itl. P.,-......! ;., .i :*,.*:,,_ '/■;. .( .u, J.. Vol. c. paf-'o lin.'i (I'.n.'i) TKSTI-sG ORES K(IK TIIK FI.OTATKiN I'KOCKSS 2!»1 from the {riiiiguc, wliich is allowed to settli'. The operation consists in afritatini; with oil anil other reagents, then a period of (piiet during wiiicii the froth eolleets at the top while the fran«rne sinks. Two windows in the side enahle the observer to see when the traiifrne has subsided sutTieiently to allow the top half to be slid along the rubber f.',isket, cutting oti" the froth from the remainder of the [Hilp. The time neeessary for the settling of the gangue is suflfieient for much of the gangue to separate from the froth, leaving only clean sulphides in the froth. This element of the machine has made it of some vjilue in testing flotatioTi oils, but in a weak froth FlO. 65. THE SI.IDK .MACHINE. much of the sulphide mineral also settles out and is lost, so that the test results with this machine often show unnecessjirily low extractions and a high grade of concentrate. On the other hand, when conditions are adjusted to give a froth persistent enough to hold all the sulphide mineral, considerable gangue is entrained in the stiff froth. Further, after skimming one froth we find it neees- sary to add more water and start the machine again to make more froth. It is hard to make the slide machine give a high extraction with only one agitation. The intermittent character of such work and the time necessary to wait while settling arc disadvantages that make the Janney or the Hoover macliines of greater utility, in our opinion. The parts ai'c of cast aluminum with a rubber gasket between. A chartre of fjOO to 1000 grams of ore is used. As regards the fineness of crushing in laboratory work, material ground as fine as 20()-mesh will yield liigh extractions with much 292 I'llF. I-I.MTATION I'liOCESS Longitudinal Section Fl(J. Gfi. IIIK hl.IDK MAIHINE. A. rpper part of cell. ('. Lower part. Ji. Riibljer cushion. D- Tail to picvent leaUaRe of froth. /v. Auitator. /•'. Hole for withdrawal of tailinsr. grejitiT case tliaii cdars.-r material. It is i)o.';.silile to «,'et aeceptahle work ill some cases with material as eoarse as 4()-mesh on coiulitioii that there is a considerable portion of the same material in tiie slime. For or.Iinary laboratory work a convenient size is 80-mesli, unless poor extractions are olitained. I The (ieneral Kn^'inecrinpr Co. at Salt Lake City and the :\rine & Smelter Supply Co.. at Denver, sell flotation macliim s. So docs the Denver Fire Clay Co., which makes a modified Hoover machine The .Jo.shua Ilendy Iron Works, San Fraiici.sc.,. makes machines tor the Minerals Separation company. — Ennon.] TKSTINd OKE.S KOK TllK KI.OTATION l'K()CES> •2'.Ki TESTING ORES FOR THE FLOTATION PROCESS— II l?y O. ('. I{\i.sT()N and (ii.i;N\ L. Ai.i.kn (From the Minimj and Scimtifiv Press of January 8. Utl6) Skpahatohy Fr.NNKi.s. ]>iirin^ tlic past year an artii I. on prai-tice in Mcxifo' nicntioncd tlic fact tliat ii.iicli of thr preliminary testing on the ore was done in se|)aratory funnels, in \vi:ich the ■ harges of pulp, oil, ete., were shaken, after wliicii t' ■• .'oek at the bottom of Fk;, Kl'AKATING KIN.NKI.. tlie funnel was opened and the tailini; run into a seeond separatory funnel for further flolation tests, the eoek being closed in time to cateh the froth. The versatility of e.xperiment permi.ssible with the use of ,sueh apparatus ( Fig. (57 1 is e<.inmendabh>. Obviously, thisi :ifr.'iiure!noot i« nt^tui ii\ tlio c-mw* .-.1^ I.,,.*:.^,.^ ,.*. ;^ 4) .. .i;.i„ 5Af. if N. P.. Vol. CXI. iiase 11.'2 (.July 24, 191.5) 2!)4 '11 IK Kl OTATIoN I'KdCKs machine ...xnpt Iliat .s,.|mrat.,iy lu.in.ls an. si,„,.l,. and iiu-xprnsiv,. hi.MoHK .M^,■^l^K. As far as we know, no small test-niaHiine l"r the Klinniv ,,r„ress has .-(.nie mt.) ,.o,u.,mn use on ae,-o„nt of the lael that thr i.mI|. nnist he lifted throu-h a f.ihe eonespondin- ^ni h.n-th to tiir rnlmnt. „f water e.|iiiva!ent to haroiiirtri,. j.resswn" J his niakrs an awkward lal.oratory machine. .Mr. Hoover (•>|.d .■le test-ma.-hine made „f .•>„ ordinary 2i-litre aeid-hottle. (See Fi.L' (i!l. I This e(,rresponds to the suh-aeration tvpe of machine and IS recommended hy Jlr. Owen for test-work wh..n such a tvpe "t machine semis neces.sary, as in ditf.Tential flotation. Air is'le.l into the pill,, throiifrh the stopper in the hottom and heaten into the jnilp hy the impeller. The four large hafties ahove the impeller prevent the swirlinir of the imlp from risinjf through them, so that there is a Muiet xone in the top of th.. machine where the froth can collect. On., frivat heauty of su.'li a machine is that aiiv froth l.)rm<..l will ris(. imm...liat..ly to the dis.'harcje. IIow,.ver. we"li..lieve that th.- .lanih-y an.l Hoover ma..|iin..s are the m.ist useful of the iiie.'hanically-airitat.'d typ.-. P.M:r.\iATic Fi,..TATi...N-. Amonj; th.. .lirtVrent piu'iimatic macliim>.s, as far as w,. ar.. a.-.|iiaiiit..,l. th.' CaHow t..st-maehine is the onlv one of lal.oratory si/e that has heen much .levelop...]. It is merely the commercial ('alh.w ma..hin.. r..du..ed in siz.. (see Kipmeiit in the laboratory u( th,. (;<.neral Engin..i.rin2 Co.. in Salt Lak.. City, has resulted in the repro.lucfion of th.. whole plant m miniature (as shown in Fig. 72i. with a Pa.-hu.-a mixer a roufrhinf;-.-..|l. .•l..anin--.-..ll. va.Mium-filter, an.l sand-pump to return mi.l.llinsr to th.. Pa..hii..a mi.xvr. As s.-,.., in the .Irawinj;. the pulp IS niix...l W..11 ui a Pa,-hii..a tank of small sizo. overflowing into the ••••,,•••: :!-:.-,;.-;:: ;;!i. i;ir Jailiiifi rr./iii tills rougiier jjoes to a saiul- pump an.l is ivtiirne.! to th.. Pai-huea, The froth is tr.>ated in a TESTINU OUES KOK THE FLOTATION PKOCEiSS— II AlK CONNCCTION Jx Pol L e yj .,./^*-^-! < T" fSvPPOf^T u u <10 Agitator 45 A a iTATOR R0TATIN6 Hollow Shaft 1 TO Aonrr Air Support AtlTATOR S ••.lu:;!.;-.t = C. Air-atonii/.iiit; lilaiiUet. D. Concentrate discharge. K. Compressed-air feed to wiiid-lioxes. 298 TIIK FLOTATION I'liOCKSS is iilliiwcil to oM'i'tlou, till' (iv»'i-f!i)\v (if t'rotli hi'injr cniitriillfcl hy tilt' main iiir-viilvcs Irjidinj; to cacli unit. After i\.v valves into the iridiviilual wiiul-iidxes lieneatli the laaeliiiie have heeii oiiee adjusted they should never lie disturhcd, and all eontrol of air .sii|>i)li('d should lie at the valves in the main ])i[)es. When every- thing? is K"'"f? \vell, the air-pressure in the eleaner can he inereased until ('oneentrate-frolh is overflowiiiff into the vaeuum-filter. A wooden i>addle to stir any settled material in the flotation cells is of value, ius well as a snuiU jet of water from a ruhlier hose for washintr eoncintrate alonjj the froth-launders and for licatin<; down froth when oeciusional too-violent nishes of froth from the cells take place, After a test is coniplete the l>ul|) should lie drained coiiipletcl\' from all j)arts of ttie machine while the air is still hlowin^. so that 7b Vacuum -* Pump. L^ FUi. 71. CAI.I.OW fKST SET. solids will not settle in passages or clog the canvas blanket in the cells. Only practice will allow anyone to get reliable results with this machine. A watch-glass for catching and panning occasional samples of froth is another necessary au.xiliary to this equipment. The cost of installing such a set of apparatus is from $100 to $150. At least 1000 grams of ore is required for a test and about 30 minutes to 1 hour is spent. It can be seen that nothing but a firiished concen- trate and a tailing arc obtained or a middling product may be left in the eleaner cell. This middling may be assayed as such and calculated into the concentrate and tailing or its sulfihides may be panned out and added to the concentrate. The machine is said to give result.^ closely paralleling those obtained with larger-scale a])paratus. A TKSTlMi ()|{i:s FOK Tin; FLOTATION I'UnCK-s II •»;iit Sdurec of sui)|)ly of coiMin-csscd air at .'i to .') lli. prr s<| in. is ii< ssary and the liiaili valves on tlit> air-pipe leadiiijr to eacli rnaeliine shoidd lie some ty|)e of needle valve in order to ensnri' exaiM 'nntrol. In ti'stint; [)raetiee, tlie air lift type of niiddlintr ntnrn has li.en found niore salisfaetory tlian tl 'ntrifiii,';il pump sliown in Fie. 71. l.\r,«iUAT(iKV .Maniim I. ATKINS. Tnrniinr Irom the description of the niaehines used to the operations on the ore het'ore and after the : ■ - " ^V'' i : i • * M 1 \ Pig. 71'. < allow test-ma( hink with I'AeiucA mixkr. A. Pachuca mixer. B. Pulivfeed to air-blanket. C. Needle valve iiir-oontrol. T>. Blanket-elanips for quickly renioving blanket for cleaning. F.. VVind-boxe8. flotation operation, we have in general the problems of crushing the ore and of drvi'ig the frotli-conceutrate. As a rule laboratory machinery tor the pulverization of ore is of the dry-grinding type, with the exception of small hall-mills that can crush from 1 to ino lb. charges in the wet. Consequently, most 300 TlIK FI.OTATIiiN rKOCKSS pt'ople (iliirt with wcIkIkmI ihurKi's of tiiiely-Krouiiil dry ore, ii known (|ii!inlily (if water, nl' nil, mni of acid or alkali. Our experience has been that most ilry-Kroumi ore must he treated in an ueiditied pulp to get good Hotatiori. Doiihtless the surfaces of sulphide particles become somewhat oxidi/.ed in, or shortly after, dry Krindin^ uiul tilt function of the acid would be to cleati the slijfhtly oxidi/ed Burfai'es. Wet grinding usually does not call for so mui'li aipette aHows measurements of the oil to the nearest 0.01 c.e., which is as close as will ever be desired. If the density of the oil is known, the volume as mea.sured by this method is quickly converted into tlii' weight of oil usc-d. The t> sting of oil samples for flotative power is a matter that needs standardizing. It is desirable to classify oils according to flotative power, but just how to do this is not exactly clear. A unit of ■flotativeness' might be established and each oil referred to that unit in terms of percentage. Jiut it has to be remembered that the best oil for one ore may not prove to be the bist oil for another, although two such series of oils might roughly parallel each other. For any given ore, it would be permissible to make such a measurement on a st ries of oils and gn)up them according to some definite standard. A standard oil might be chosen and the value of a second oil expressed in percentages of the flotative power of the first as determined by using equal quantities of the two oils in tests on an ore under identical conditions. This test could not ))e fair for the reason that clifferent amounts of two different oils are necessary to accomplish the same results. Further, the conditions of acidity or alkalinity might favor one oil and handicap another. If we mea.sured the amount of oil necessary to give a fixed percentage of extraction the first of the above ohiectinna wnnl.1 Ko outicH...! l,..t i!»: " ■••"- t:;;:juiiit;!i:-; rj of acidity or alkalinity could make the test unfair for ^ . some oils. Hence the dilemma as to a standardized test of ^^°' '^' a flotation-oil. "'""'"' PII'KITK. z3 - h 302 THE Fl.dTA'i'IllN riiOCESS No single test could difiiiiti-ly i)lace an oil in any sclionie of classi ligation and iiothiii^r < an he done imt run a scries of tests using varying anK)unts of the oil to be tested and with varying acidity or alkalinit\. The temperature of the \m\]> iiuist be kept constant although it has a minor etVect. Coutts gives about the only directions on oil testing that are to be found in the literature of tlie subject". lie states rightly that the first tiling to do with an oil is to measure its density, for future eab.'ulations. as it will be measured by volume in the laboratory and nuist latei- be reduced to weights. He recommends the use of a burette for measuring the oil. but we favor the ilolir pipette mentioned above. Tie chooses a standard ore on which all tests are to be run and classifies three ditl'erent kinds of standaid tests: (1) for mixed sulphides. (2i difTerential sei)aratiou. and ('■]) flotation of copper and iron sulphides. He states that oils high in phlanderene have proved best for differential separation of zinedead sulphide ores. While this is helpful, he d' .s not state just linw the oils are to be cla.ssitied after tlie tests liave been made. INIuch work with oils is needed in order to determine if there are any definite constituents in oils that give them flotation power. Research is also needed in the preparation of oils from the wood, coal, and mineral oils in such a manner that they will have maximum etTfieiency in flotation. Work on this subject has been initiated in our own laboratory and it is known that several of the larger companies have employed oil chemists to look info sueli ])roblcms. We nndervtand tliat most excellent ,vork is oeing dom' on methods of modifviig and reconstructing oils that can be had cheaply. By this we mean more flian mere mixing of a good flotation oil with a eb.eaper non-selective oil. Sulpluitiaf ing the oils, dis.solving them in acicls. dis.solving modifying substances in the oils. etc.. ar(> some of the ideas being tested with varying success. It is on account of all this ,iil testing that considerable progress has been maile in flotation during past year. that now most of the larger eiinipaiiies ,•'.:•;■ using cheaper oils than a year ago. When starting to work with a new ore. ther(> is needed a rai)id qualitative iii.-thod of choosing an oil tliaf seetns well adapted to the flotation i>\' the ore in i|ue.sfir'i. Such a scheme is in use in the I.Mhoratory of the deiicral EnErineering Company at Salt Lake rifv. 'I'lieir (lualifative tester is desiencd to test oils for use in the ('■.ll.uv iiiiPiu.intic flota'ion ceil and consists of a urlass tube of about nj. Coutts. !■: .( .1/ .', Vol. XC!X, li:mo KtTO (UHr.V TKSTI.\(i OHES FOH TIIK II,()TATI(».\ I'HOCKS .•{(Ki two inches diameter and two t'ei-t lon^^ {F\'^. 74.) This can he set on end and closed at the hottom with a one-hole rubber stopper through which passes a glass tube into a small canvas bag. The small hubltles of air coming througli tlie canvas are similar to those used in large-scale machines and can be observed through the glass walls of the tube. With some pulp ii. the tube, oils, acids, .salts, etc., may be added in very short tests until the proper appearance is obtained. An overflow lip is provided i case it is desired to e.xaminc the mineral in the froth. A slight adjustment of the air will provide an ample overflow of froth. Disi'os.vL OF THE Frotii. The handling of the flotation froth in the laboratory finds difficulties which are reflected in practice. ^ ;.\V^ J Tuhe pl>'/> .^A ; • y\ Fig. 74. qu-M-itative on, tk.stkk. It is often very slow to settle and filtei-s with difficulty. A vacuum- filter, connected with a laboratory a.spirating pump, is a very convenient method of getting the concentrate out of the froth. A large porcelain Buechner funnel fitted into a filtering flask, as shown HI F'g. 60, is used at present in our laboratory. A copper vacunm- fiiter of much the .sjime type, provided with a porous false liottom of acid-proof wire cloth, resting on a punched plate, is shown in Fig. 71 of the Callow test set. Filter-papers ca.: he laid over the bottom of either of these funnels to coUect the concentrates, and the vacunm beneath sucks out the water and oil of the froth. Such a tiltcf can be placed under the froth-discharge of a flotation machine so that a fairly dry cake of concentrate is ready for further drying at the end of the flotation test. Ry loosening the outer rim of the filter-paper and then turning the funnel upside down over ;. pnii, (lie filter-paper with the concentrate can be dropped into the drying-jian by gently blowing into thi' stem of the funnel. This is set aside in a warm place to dry and later weigjied against a filter-paper tare. Tf it is desired, tiie froth can lie collected in a gla.ss beaker or 304 Tlir. n,()TATI(IN I'UdCKSS ether vessel and allowed to .stand ovei'iiiglit. A layer of elear water can then he sij>iioned otf and the tiuek pulp remaining liltered or dried direct. In some lahoratories the froth is dumped onto a shallow pan on a hot i)late and tiie water evaporated. Oeoiusionally such a sample of froth will he left too loiif?, and will he ifjiiited and roasted. We once used a innnbered set of shallow ])ans t'or such evaporations but i)refer filtering before drying the precipitate. A numbered tag is now put in each pan along with th" cake. The ])roduets coming from the flotation machine should be watched closely and occasionally panned or e.xannned with the microscope to see what kind of work is beiin,' done. This is t'airly Ciisy to determine as the sulphides ,;i\ mo. ')f them distinguisiied easily from the gangue under the niier's oe. and likewise gangue particles in 1hc froth-con. •ciiti-ate I'an often be distingnislieil. .\ microscope is a most usef'd adjunct in a flotation lalx.ratory or mill. Of.nek.Mj ("(ixsU)Kii.\Ti(i.vs. We have mentioned at various placi'S the relation of the laboratory tests to the large-scal(> operations and now repeat that in almost every instanc(» the laboratory results are somewhat pessimistic as compared to large-scale work. The reasons are made apparent by the smallness of the machine and the .shallower layer of froth often formed under thesi' conditions. Moreover, labora- tory operations seem to call for greater amounts of oil, acid, etc., than do the large-scale operations. Oidy one of the above machines is adapted to 'roughing' and 'cleaning' operations in a single test. Present-day practice tends toward re-tr(^atment of at least pai-t of the froth in order to make cleaner and higbei'-grade concentrates. ronsequently, it nuiy lie desirable to collect enough froth from a series of tests to be re-treated in a 'cleaning' test. Of course, this is ])rovided for in tlu' Callow test set, where oidy 'cleaned' concentrate is d!sehargerh and analyzi' some of the s\iccessive fi-actions of the froth beinir disehiifired from a flotatiiui machine, as the tailing becomes leaner, and determine at what point it may be desirable to re-treat such froth. ilany rcpoi'ts of flotation test-woik \\'A\\ meclianical-agitalion machines give the speed of the rot.-ition of the agitating-blades. We have found that it was ])ossible 1o u'et much the same wcrk doiic with (|uite a \ariation of sjt Is. the only elTcet being to lengthen or shorten the time of treatment We feel that the iirii)ortance of tins matter has been nnicii ex.igi.'ci'aieii. Sumc means oi Npei-ij control is necessary and the sjieed can be adjusted in each case until TKSTINd IIRKS KOK TlIK Kl.(ir \TI( IN I'KOCF.SS — II .■{05 Fit;. TTl. TIIK (ASK MA( MINK. tho fl-Dtil presents the proper iippefiraiiee ;is tn (leptii. siiz,. of l«i!M>!i'fi. edlor. ete, Speedjiii; tiiwiinl the end of ;i test in order to pivo a deeper froth with a faiMt line of concentrate on the very top is often :!ii(; TIIK ri.oT \ri(iN I'liDCKSS ii(l\ isiililc We rd'ominoiid adjiistiiic; tho speed in caeli tost to suit tiie other conditions, rather than niniiiiiij: a series of tests witli dirt'erent sjieeds. Only in the slide niaehine, where operation of the impeller must l)e suspended in order to allow froth to eolleet, is the speed of mueh importance. Here we rei-omniend agitation for a delinite leni;tli of time, and then a ])eriod of settling;. The elTeet of variation of sjieed during a definite length of time nwiy he a considerable variation in tlie amount of froth eolleeted dorins; the quiet period. ITenee wo are prejudiced n<;ainst tli(> ise of the slide niaehine except for oil-test intr. AVhen a ^ood set of conditions has been found for the flotation treatment of an ore. it is best to recover the water from each test to see what elTeet a closed circuit of the mill-water will have. Som.' oil and chemicals are thus rei'overed. cuttiiifr down the aiiiouiits necessary for operation. In a carboy or two of the water to be used in the lartre mill s! ■ 'e used to make cei'tain tiiat no deleterious contamination will ensue from this source. I'lidcr tliese conditions filtration of the concentrate and tailinir for recovery of the water is necessary. Such conditions are provided fiu" in the Tallow a]>iiaratus. above deS(>ribed. and can be appliiMJ easily lo any of the other ii.achines. Oil sainph's for test purposes can be obtained from the various wood-distillinpr companies now advertisinir in the technical |)ri'ss. from qras companies and from petroleum-refiniiifr companies. Til altackinc refractory ores, tlun* are a Tinmb(>r of intreiiious thintrs that can be done to the pnlp both in and out of the machine. The troulile may ho (lii(> to deleterious substances, which sometimes can be washeil out. rendered harmless by boiliiis, or by ai'idifyinsr. or liy makintr alkaline with lime before entering the machine. Occasionally. th(> ore will not work well under ordinary conditions but will yield beautifully after finer ^rindin?. Sometimes extra reagents are necessary, such as powdered charcoal, modified oils. argol. soap, calcium sulphate, alum, etc, \ rational method of devisintr tlie ])ropcr tests in such casi's must be liased on some theory of tlotation. Colloid chemistry is a branch of knowledgre that we believe to be very neces.sarA' for sucli work, as it has facilitated a more intellijrent control of our tests and has frivi'ii wonderful results in a niimlier of instances. Finally, it is well to be proditjal in the amount of analytical work connected with flotation testing in order to discover interesting difTerences in trangue-coiistituents carried ito the concentrate, as TESTING ORES FOR THE FEoTATluX PROCESS — II :i()7 Well ii.s to timl the i)est (.'oiulitidiis Tor Ifaving out some yaugue constituent that is less desirable than the rest. If an experimenter does his own analytieal work he can he expected to spend three-fourths of his time analyzing what has been done during the other fourth. Sununariziiig the most important points to be tested on a given ore with any given flotation maeliine, we have; Method of grintling. Fineness of grinding. Kind of frothing agent nsed. Aiuount of frothing agent. Acidity or alkalinity. Temperature. Necessity of preliminary agitation. EtTeit of addition-agents in flocculating gangne-slime. It ciiii b(> seen that there may be a certain best combination of the above variables that will be entirely misised if a great many tests are not arried out; hence the desirability of doing the testing in a small ialmratory-macjiine where many trials can be made in a short time. After the liest conditions have seemingly been established, they should he further tried in a larger-sized machine before they are incorporated into the general practice of a mill. The test-work on this scale need hardly be described, as, for the most part, it is a question of translation of laboratory results into large-scale operation. I We have added an illustration of the Case machine, evidently a modified Hoover apparatus, made by the Denver Fire Clay Co. — Editor.! 308 Tin; KI.f)T.\TI(lV I'UdCKSS MOLECULAR FORCES IN FLOTATION Surface Compression l{y Drill, Kv II. N'diiuis (Fi(im tlic Miiiiiii) mill Siiriilifi,- Pi,.',.s of Feliniary 12, Iflldi At the iiicctinir nt' tlu' local inciiilifrsliip of Ww AiiuTU'aii Institute of .Mi;iiii-r Kii^'incns on i),criiili,r 14 hist the question was ask.MJ by one of the sjiiakers: '-Why docs the {.Teased needle float on tlic surfa<-.' of a tuiiihhT of water and the welted needle sink.'" Did one or another of the exjierts |>re.s..nt rise and say tjjat it was due to 'surfaee tension' and then in a few well eho.sen words e.\i)laiii jnst exaetly what •surface tension" is.' Xotliinj: of the sort happr-ned. The (pii'stion was II )t only not answered, hut it was unanimously avoided. It is a fair <|uestioii. however, and desei'ves an answer. Tiie fact is that 'surface tension' is a iiiisnonier. Tension is a stretehintr. whereas the phenoineiia, in (|iiestion are tliose of I'jni- lires,si,-.n. In "surface tension.' a hiihhle of air oi' a droj) of waler IS pictureil to the iiiias.'ination as hein>r actually of the f.u'ni that it woiil.l have (■/ it weiv contained in a tiliii like that of a soap-huhhle or a toy-halloon. That irrasped. th.' suhstarice of the huhhle or of the droji is iirnored and we are asked tooccujiy our minds oidy with the imairinarv lilm. The reasoniiiir appears to lie: "There miifht he such a film, there must he. then. is. Otherwise, we ai'r not ahle to explain it at all." In what follows. T shall attempt to explain the plii-nomena dis- cussed ill terms of molecular attraction and of heat. If you will till a tunihler with water or other li(|uid and then con- tinue eai'efuli.\- to pour in iiku-c; instead of running; over the side, there will he a lieai)inef up of the li(|uid in tli(- tumhler ami a roundin.i; of the surface, the centre of the liipiid heiiur as much as a sixteenth or even an eitrhtli of an inch lii{:her than the rim of the tumhler. That is the plieiiomeiioii of your 'siirfaee tension' |)urc and iindetilcil. The .same jihenomenon is seen when mercury is contained in a (.'la.ss ves- sil, even when the ves.sel is only partly filled. Mercury does not wet irlass. an 1 where the liquid metal meets the siilc of the jrlass vcs.sel the mercury is convex. "Where, however, the tumhler is only partly tilled with vater the surface of the watci' is concave where it meets the inside of the tumhler, and the -.'lass is welted hy the water. I.. *l;;i A! ■..".-..■.'. ^..i..i-.. ; : i i : . : . *■• •••" -*:;.::::: ;:•..•:.*::!;:; :',■;;,;■ ;; ;',as .^TitTeu Tiuii >mi ijiee ieil- sinn is a force existinfr in the surface of a li(|uid that tends to draw the |i(|uid into the f(U'm of a sphere, this hein-.' MOI.KCn.AK KoKt'KS IX II.UTATIo -SIKFACK CoMrUKSSION ;{()!i till- most (■(impact I'di-iii tliat a ^'iveii volume oaii a.s.sumc and tlu" I'oriii ill wliich it jimseiits tiic Ica.st surtVe. This is a lovely specimen of tlie lofjical fallacy known as post hoc (rathetic world. The sphere eouies liii;hly recom- mended. It is moved and seconded therefore that the molecules form a sphere. So ordered." The calculus i>roposition that two homogeneous spheres attract each other as if their ina.sses were collect(Ml at their eentres of gravity is as true as anything human can be. It is also true that in a single homogeneous si)here. if acted on by no ou'side force, the cohesive attraction of its molecules for each other will act radially toward the (•entre and form a .sphere: and it is this radial attraction and not an imaginary film or a non-existent tension, that eauses the phenomenon, and it is probably some similar molecular attraction that eauses mineral flotation. In James Clerk Maxwell's article on capillary action, in the Kii- iiiclopiiilia Britniniiia ( \ 1th edition), vol. f). p. P.IR. he .says: •'Plateau, who made an elaborate .study of the ])henoineiia of surfa'-e tension. adopted th.e following method of getting rid of the efT(Hts of gravity. lie formed a mixture of alcohol and water, of (he same density as olive oil. and then introduced a quantity of oil iufi^ the mixture. It assumes the form of a sphere under the action of surfa'-e tension alone." That it assumes the form of a sphcn is granted. Tiiat v.n\. face tension d()cs it is denied. The toy-balloon has a i)lace in a rational explanaticm of the phe- nomei:a under discussion; but the allegid film around :. droj) of water or aror.nd a bubble of air. or as the toji layer of a liody of water, like (he film of a toy-balloon, has no existence in nature. Th(> vendor of toy-balloons has each one of his gayly colon d stock fastr'ne.l hy a string, which serves the double purpose of keeping the gas in the balloons and of keeping the balloons themselves down to earth. The :tl(> Tin; II.dTATloN I'UOCK; I'l-fi' ends lit' t!ii' stliiil,'s ;nv lir(iii-,'lit to ;i .•oirimnri knot. Tliriv is :l pull (111 each string' ali'ni)o.se eacli molecule of ,>ater in the tumhler to he free froTH the attraction of i;ravitation and in the form of a sphere, then the vertical section of the surface layer would look like this: Centre o/ Crgvitv FlO. 7G. KOH( KS .AFFECTING SURFACE OF W.\TtR. There you have the stock of toy-hallooiis with the strinps connect- ing each with a conuuon centre point. C is the centre of gravity of the water in the gla.ss. The lines diverging from C show the ilirec;- e .iin.i I veiiicai lines uovvnwaru from each molecule indicate the lines of the force of gravity and the arrowhea<]s on the cohesion lines mark the opposing forces of heat MllI.KCII.AK l-.IKCKS l.\ Kl.(n\ri.).\— SI HKACK COM I'HKSSK IN :ill and col.moii. 1„ th.- triai.f,'!.'. C a ,1. f..,- exaniplo, tl„. l.vpotlu.ni.s.. (' d represents llie loti.l for,-,. „f e„li,.si„n : r „ ,s its v,Tti,.i,l ,-,>Mip„n,Mt, aii,i a ,1 its lu>ri/oiitiil i',)nip„neiit. Tii,' r,'siiltaiit >,( nil i|i,.s,. hori- zontal .•oniponenls ,/,/, ar. ah. etc., is a fon'o etr.M'tinsr u ,'oiMpr,,ssion ,.f the snrtm-e of tli,' wiit,T. A p.o.l idea of tl:.. stni,'tnr,. of sinfa,'e eoinpirssio.i is siioun l,y lli,. rip," s.M.,l-|i,f| „f tl„. ,.o,iniion ,lan,lelion. •Ill, hut uat,'r is not I'oiiipn'ssihl,'. Tin,' itiou-,'!!. t,i any s,'nsil)le depri',' liy an ,.xteri,.r f,)n'e : liut the int,Tior loir, s at w,,rk in water do many \von,l,.rful tliin>rs. For instance, they ,'aiis,' water t,. ex- pan, I on c.olinj; an,l to e,>ntra,'t ,.n healing', between C. an,l 4 ('., aii,l all thi' wat,'r i)lienonicna of o,'eans, rivers, and rain fall, of liy,lranli,' an, I of st-ain powiTs. ami of the irresistiiile foivc ,,f freez- in-r. are eaused by the niohrtilar a,'tivities existin<: in a ,lr,)p of wati'i'. One reason f,)r la.'k of a elearer un,h.rstan,linf; of these phe- nomena is the faihnv t,. p, PNive the fa,'t that th,' tench-ney to form a sphere of wat.-r in the tiiml.h'r is in,'essant. whi'ther the attraetion of fjravitation acts on the mass of the wat-^r freely, as in falling'; is war,]e,l otT". as in I'latean's ,'Xi),Tiini'nt : or is super-imimsed upon the attraction of collision, eonipellingr the water to conform to the in- fi'rior shape of the tumbler and rendering the ever-present coliesion ini'onspieuous. The action of water from the hisrlier decrees of tfmi)erature, thronsrh 4" C. to ice, is shown by the aecompanying ,lrawinf;s. A mole- Fui. 77. VOI.r.ME AUOVK 4° c. VOI.IME AT 4° C. VOLIME AS ICE. eule ,.f water, composed of three atoms, is plausibly ivprcsent,.,! by a triangl,'. Two such moh'cules arc separated a ,M.rtain distance by a correspondiufr amount of heat, and tiiis distan,v tix,'s tiie volnm,> of I lie mass 01 water, which increases and diminishes as the decree of heat is raised or lowered. At 4° the volum.. of water is at a minimum and it is a fair inference that tlie molecules of water are at that point :ilL' Tin: i-i.(i'i\ii, ,.v ri(,,cK> M.'iinT t„ ..arl, otl„T tliMH al any ,„,n,i |{,.|„u \ C. ih,. nn.l.vuhir l|"v,..s ,vart ,„ si.rl, a inaniirr as t.. .-aiis.. a rlian-,. in tli,. .vlati.ms of IIk' ni(,|..,.,ilrs lliriMsrlvrs. raiisuifr tt,,,,! t.. turn aihl in tiir Stat,- of i'v-t„ assninr tli,. i.osilions shown in ti„. tiiini li^'iuv, with a Iouxt siMTil,,- ^rravity than tiir wat,..- had iMior.' fivcvin- \,, „th,.r funrs are iK-ccssary to Ih- .•aiisation of th,- iihrnoMu-na iii,ii,.at,.,l tiian tiiosu ol cohesion ami in-at. Ilerr, then, is tile answ.'r to the .piestion askcl at tlie iiir,.tini,' : l?y rrasoM (,r the horizontal eoiiipoiients of the attractions of eo- liesi..n whi,.h ,lraw each molecule of water towanl tli ntre of ^'ravity of ,ts mass, the si rface of the water is .■,„„, ..vsscl. ma.h' "K.re ,i,.ns,.. a.Ml otVers a resistance to the nee.lle -reater than the ''■'■'-'" "'■ "••' ' 'Il-- That wei-ht is imt suftici.Mit to break apart tile surface molecules. Imt only makes a sli-ht in.jentation on tlie ■surface. When the nee.lle is wettd. eai)illary attraction raises the comiMVsse.l surface over an. I ahove the n.'e.lle wlii.'h. no longer ivstin- upon the .le.iscr surfa.-,., Init in water not under surface compression. ol„.ys tlie attraction of gravitation ami sinks. Attention was eallcl ahove to the two cases of simple compres- sion where the entire surface of both li(|uid.s. the water in th.. 1, rim- full tumhhr and the mercury in the jiartly tilled !.da,ss vcss.d. an- •■oiivex. whereas in a lumhler partly tilled with water, tiie edire of the wat.'r. where it ii ts the u'lass composini: the lumhler. is'con- <'ave and th.. wat.-r wets the -lass. Thus there is a.ld..,l a n.-w force whi.'h m.)dili.s th,' surfac c.mipressi..ii ,.f th.' wat.-r and .Iraws th,' water at the cdcre upward on the crlass. f.irmin- a eon.a\ itv tan-.-nt to both th,' surface of the watiT an.i the insi.le of th.' tiimbl,'r.~ Ft niak,>s no .lifTereiice liere and now what this force is call. '.I, whether colu'sion or adhesion: whether it is the same molecular attra.'ti.m that exists h(>tw,^en th,' moh'.'nl.s .,f the water or wh.'th.'r it is the coh,'si,)n of the L'la.ss actin- at .sensible distanc-s. or n.'ith.'r. or both. Thi> wat.'r is drawn ii[i. not pus:;.>d up. and any .Irawiiiir uji is attrac- tion, an.l a.-tiiiL' <>u niol.'cules i- ; molecidar attra.'f ion. In a tumbl.T L'J inches in .liamct.'r tlu' lioriz.intal concavitv atrain.st the -lass seenie.l to b,' about ,',; of an in.-h wi.l.'. perhaps a litth' more, l.'avin- alwmt L'il in. of .'onvexity to I in. total coneavity, ' out of th,' .liam.'ter of I'i in. The v.'rtieal con(?avity seemed al.-io' about ,V; of an inch alon- the inside of the trhiss. With ulass tub, s of small. 'r .liaiiii'l.T the horizontal .'oncavity sei'med to remain about tlie sam.'. but thi> verti.'al .'.jncavity in.-ri'a.se.l as the diam- eter diminislie.l. The convexity at th.' centr,' of the surface .le- MUI.KCII.AK KOKCKS IN Kl.oTATlON— si KFACi; (n.MiMIK.- ■ilON .n.} en.,.s..,l with tlK. .lia..i,.t.r of th. nyr\r a„.l i„ a t„h. of ( ,,. .lia.n- .■t.i- tiR. surlaee of the wator was a,, inNvrt,.,! h<,lh,w sph.r,. whh „o -•'•"Vt.Xity at all and its h.i^Mit ahovo th. h-vl of th- wat.T in the tnn.hier was > of an .n,!,. W„l, a tub,, of ,', in. .i,a,n..t,.r ,h,. wat.T I'aiiic n|> j incli. The surlVe compression at th. ,;U,r of the water in (he tinnhh-r .s less than nearer the eentre, hein.^ ,,rae.ieallv /en,, and olfern..^ HO n.sKstance to the upward attraetio,, npon the water if a -i-iss tuhe he partly immersed in the water in the tiimhh.r, the water in II..' t..he even if oj.en at the lower en.l, for.ns a separate ..ohesive ...ass, m.iepen.lent of the rest of the li,p,id with all the phenomena 01 capillarity. It. has l.een said above that the cohesion of the wat,-r varies in versely as the temperature, being f,^reater at the lower than at the higher temperatures, a.id at the boiliuj, point there is no cohesion Witt, the .same chan-es in temperatur,. the attraction between the water and the jjla.ss sides of the tumbler varies exactlv as the co- b.'sion vanes, and there is every reason to believe that the forces Heyafnir the liquid are those of cohesion of the water and the .dass aetin^ at sen.sible distances. Thes.^ ,.l.en„mena between the water and the mercury on .me han.l and glass on the other are, of course those ot capillarity. They s..em to fit in with the above theorv of surface compression. Then what is ther,. left of true surface fusion ? Well there is the soap-bubble. I made some experiments in this direction a few davs ago with r.O or 60 .soap-bubbles from 4 to ^ inches in diameter The'se were burst over a dark hardwoo,] table about ,% inches square so that tl.e resulting wet .spots on the surface of the tabl ,uld be examined ( are was taken in every ca.se in blowing the bubbles to remove th.- usual drop of water at the south pole of the bubble, so that all the wet spots catne from the wreck of the disten.led film. After each bubble burst the fable wa.s wi,,ed dry for the next one Wh.n infl-, t.o„ eease.l. one bubbl,. .T inches in diameter shrank an inch before it burst : another shrank from 6i to f, inches. In both ea.scs tl„. air was expelled by a real surface tension of the bubble's film Most of the bubbles were blown until they burst, at from 1 inch to 2 feet above the table. The ones at 1 inch spread wet spots in circles from 7 to U inches ,u diameter. Of the bubbles that burst at greater .bstances from the table, .at fi i^chrs r.hr.-.:- +!-. Mpois c.vlcnded to the edge of a circle Ky inches in diameter: at 12 inclu-s above oo in..hes: at 20 inches, 24 inches: an.l at 24 inches, :iO inches ("ount- :tl4 TiiK i-i.iir \riMN iMicMi- inu' II i|UMrliT circle. iIu'Tc xmtc Ircnu 17") Id L'tin wct s|iii!s, or Tmi \i< KMiu Imp .'iic-h iiiililiic il ujis (■viJ the lilin acted tn re unite the ilistetnleil watery moieeiiles and, as tln' shortest distance liitweeli two points oil the ei rclllll l'e|-ence of a sphere is iiieasiircd on the •rrcal ciicle that joins them, the reiinitiiit; imdeeiiles took that roiili'. tia\elin'r ovei- tin' sphei-ii^al siirfai-i' of the huhhle, and uheii a niinilier of them net and formed a drop, all the nioleeiiles \\erc attracted with a eeitaiii force. 'J'he lantreiilial components y what stret , hy '■. liat torture, of the imairinat ion can these |)lieiioiiii'na he lirou<;ht into identity or even the least ri'Semhlancc with those of the placid Hoatiiifr of the trrea.st'd needle upon the compressed siii-fare of the water in the tiiiiiMer .' .Mr. Charles T Diirell in an arliidc in the Miiiiiif/ anil S(li iilijir I'lusn of .'■';, i-'ii t is. 1:11). 'iititlcd "Why Is Flotation.'', diselis,ses the rising of a 1ml(l)le tlirough a liipiiii and says: '■Suiia;( tension causes the luoleeiili's of the liipiid to form a liliii around the liuhhie and remain with it to the exclusion of like inoleciiles during th<,' time the bulilile remains in tln' liquid. To all intents and |)urposes, this tilni is seen to he the same as if it were a iiu'iiiliraiio of some solid. The air ill these Inihliles can no more come in eontact with the li(piid through which it is jiassing tlian it could were it inside a toy halloon, foi- instance. The biitilile may lie said to he enclosed in a 'liquid skin.' As a proof of his argument he cites in a footnote tlie following: "A striking experiment to show tlicsc li(|uid films is as follows: To a breaker partly filled with a colorless oil, add a small quantity of jier- niauganate solution. Blow air through a finely drawn-out glass tiitie into the permanganate solution now on the bottom of the lieaker. Air liiibhles enclosed in the colored liquid film rise through the oil and break at tlie surface, liecaiise of the expansive fore<' of the gas. The colored water drops back through the oil exactly in the same manner that a halloon, Imrstiiig, drops to tlie earth,'' Witli these instructions the following experiments were made: A MoI.KCl'r.Mt l(iU(i:s IN II.OTAIIipN ^1 HIACi: ( iiMl'Hl,>--/(iN .•!i; ',,i\rr (>r Uiilrr, liair iiii indi tlm-k, ciildi.d clalk Mur uilli a ,|_vc ikiI SipIuIiI.- ill ktTnM'llr. Wa.s |IUt into n lllillhlil- illld llllrc llichis (if Vihitr k(r iiaviiij; a rulihcr Kiilli and a ,',.-''1 ''"''■ i'l tl ml nf tjic i,'lass luli. . 'miMiIcs nl' air wn- tilown into till' liliK' wairr, tin- end of the f,'ia.s.s rod resting 011 tiie liottoin of till' tuiiihlrr. At lirst tlu' ihtssiui' on the Inilli was made viTV sTriilly, tiif idea licini: to liavf llir luihlili-s 's vMiall as possiMc. As iiiiin\ as 2(1(1 of tlicsc tiny Imlililfs wen lilown and tiicy ros«' to the snrtair ami foriiicMl a jrroiip. Sonii' luiist. some wcii' i'lcorporatcil \\itli olhris, and tiiiaily, of course, tiny all l"ii-st. H\rry oih' of tlicsi' 2(MI hiilihlrs liiirst within a rirdr of half an iiirli. and that cirdi' from tlio limi' of tile lii-si hiililili' until the last orii\ \v,-is not fi'cr from liiilihlis. oiii' touchinjj anolhiT and all forming,' a .siii'.'h' compact Uroiip; hut at no time, in the stroii',' sunli>.'ht, was there the sli^'htest tnico of hliie in the circle nor ;in.\ where in the kerosene. The ui)ward hound III hhles were pcrfceil.' white and thei'e Were no return pas- seiifrers. The huhhles had no films hut were sim|(ly holes in the water. When tlu'y eaiiie to the joint surface of hliie water and k- rosone, they slipped into the kerosene, iiiadi' holes in that, and hui-st at the surface with no trace of a tilm. Then, with f;reatcr pressure on the hulh, larger huhhles were hlown, and with them, small (|iiantities of the hlue water were forced u|) into the kerosene. When tlies*? eaiiie separately the air ros(^ to the .^lirfa-.' Mini the water dropjied hack, hut wln^re they came to<;ether the air buoyed the water up to the surfaci' where tli(> air escaped and the hlue water sunk through the keroseiii' and disappeared. With greater pressure the liubhles hecanie still lar^rer, as did also the size of the drops of water forced out with the air. Where trapped together the larger masses of air and hlue water joined and rose to the surface, as a single entity, .sometimes very rapidly and sometimes very slowly, liiit in no case, whatever the size of the constituent parts, was the air-hiihhle hlue. There were never any water-films. The rising com- bined air and blue-water drops in the eases of the larger bubbles were in shape as if the bubble were sitting on a tiny blue feather })ed. In every case the blue water was below and the white bubble above an;I the buhlile was pulline the drop to the surface. Sometimes the drop was ton heavy for the bubble to float and both sank to the water layer and reiiiaint>(l stationary until the drop merged in the blue water and the bublile was released. Wiien tile smaifer iiui)l)les rosi lO flie surtaee of the kero.sene they did not break as quickly as in water but seemed to strike against the :{](; llll. ll.ilT.MIdX I'iiUCKSS iiihlrr siilr (il' ihc .siirl'aiT slr.iliiin iiini rflKiuiid ddunuaril mikI uiiiviiif: (IV. T t(. Ill,' v,\ (,f tlic iiiiiil.liT. On iifiirinir the jrhiss tli.-y si-fiiicd to liM IIS if iitlr.i.'tcd ii|)uar(ily. llkr tlic ])ai1 (,l the surfai-i' stratum aroiiiiil the filirc iiml'i' cai'illary atli'ai'tidii. Siiiiic other intfnstiiifr plicnniii.'iiii of uupillarity ucri' notircil. In the liliii'-clrop-kiTi'srnr fxp.'rimcnt tlir sidi^s of tlic irlass were wetted liy the kerosene, cv.-n I.elow ih,. joint siirfaee of tlie Ii(|iii(}: Imt not- witlislaiidiii^' this faet there was ()l)served the concavity of the blue water under tlie oih se,'niinf,'ly warrantin"; the helief tlial the attrac- tions lietween tlie water and the ^'lass look i>lace throu^rh the inter- mediate (ilm of oil. Wilh a liody of mercury a jzlass tuhe pushed below the surface showed a rounded surfai-e of mercury within the tuhe. with no I'apil- larity the ronndi'd surface hi'ini,' due solely to surface eompressioii. With the tube fioatinyr in the iiienMiiw th.' level of the outside mercury was exactly the same as the top of the rounded contents of the tuhe; but when the tube was pressed down into the mercury the level of the iiii'reury in the tube was lowered. It set'iiis likely that the indentation of till' tioatin'T nei'dle and the loverin^' of the level of mere'. ■• in the jrlass tuhe are both due to the resistance of the surfai'i' compression to the entrance of foreijrn bodies. Tn the expei'iment of the blue water, tin' bubbles and the kerosene, we come most unexpectedly upon flotation, or its counterfeit. If it is flotation, like the mineral flotation, iiow is it to be accounted for? If it is ditreivnt. what is the ditVerenee '.' Will an explanation of il.- lilue-drop kerosene flotation lie that of mir.eral -.lotation. or will it help in that din ion? There is surely an attraction between the air- bubbli' and the i.nie ilrop. or \>hy -liould they stick toiretliei:' The blue drop is heavier than the kerosene and the bubble of air li>;hter. One pulls uf> and the otiier pulls ihiwn. Why do they not sei)aratc unless there is a jjositive mohcidar attraction between them? Why does the bubble, restinir upon the blue drop, liuoy both to the surface of the kerosene, except for some molecular attraction between lilue di-op ,.iid bulibh'? Where this attraction is manifested, even sliL'lilK. it is helped by the static pressure of the li(|uii| medium in whieii th.' flotation takes place. The trreat unsolved problem in flotation is the identity of the forces that do the tloatinir. Some say that it is surface- iension. some eh'ctric'ity. .ind Miine moh-eular attraction between the nir-butibles and 111'' lie falbc pai-tiidcs; and there is always the mystery a: to exaetlv i'uf pan [liayeii iiy liii' oil. Tn tiiis article ii is mti'tnlcd to show that M(II.l:CI'l,\l{ IllKCKS IN rl.OTATIO.V SIHFACi; fO.MrUK: -II >\ :il7 thrrc iirc ('(.rtuiii iiK.ltrular attractions betwoeu widely dit^Vrfiit siil.- istaiiccs whicli Wdiild sri'iii to lie nothing more or less than the foiv,. ,,t' cohesion acting at scnsihle distances, but for the circiiiiistance tliat such an interpretation runs counter to our pre con<'eived opinions as to nioh'cular attractions; hut tiiese attractions are shown in this artii'le to exist between ghiss and oil. between glass and water, dircctl.v and through an intervening film of oil. between glass and air. and between water and air. The iiiipres-sion remains that a tliorough examination of our pre-coiiceived opinions may show that tluy are fallacious. There arc strong reasons for believing thai the state of .science today is not uidike ihat of learning at the end of the 12th century, at the time of the great awrkeinng. when the worhl dropped the seholastieisni of Rom.- ami went back to the phikisopliy of ancient tireece. We have lost the faculty of studyine: phenomena, we are ignorant of the first jirinciples of logic, and we have degenerated into mere juggling with names. Proof of this iMdictment is found in Vol. XXIV of the hhniirh,- piKlia Britanniva, at page 401-2, where it is stated that the pa.s.sage of electricity through liipiids bail been explained as a transference of a succession of electric charges carried by moving particles of matter or 'ions.' Then it was discovered that the moving particles ',hat carried the electric current were nuicli smaller than the atoms of hydrogen, and they were re-named 'corpuscles.' They enter into the structure of all matter. The oidy known properties of these corpuscles ai'c their nuiss and their electnc charge There is reason to believe that the whole a,j)|)arent ma.ss is an effect of the electric charge. "The idea of a material i)article fiins disapjtears and the corpus<'|c becomes an i.-iolated unit of electricity— an electron." This is a typical 'sejen- tilic explanation." It siarts out inventing tli,- word 'ion', which it inniiediately re-christens 'corpu.scle' and then 'electron.' and the only meaning that can Ijc e\lract(>d from the argument is fluit electricity is supposed to he made up of imifs. a purely gratuitous assumption. Here is another on the same i)age 402: ■•Maxwell and Hertz showed tha' the velo,-ity of i)ropagation of lighf and idectro-magnetic waves was ' lentical and that their other prop rties differed only in degree. Thii, light becomes an eleetro-rnagnei le i)!ienomciion. Hut light is started by .some form of atomic vibration and to start an electro- magnetic wavi» re(|nires a moving electric charge." Here are tliree sentences all fallacion.s The peculiar tendency of the human mind which substitutes em[ity 318 TIIK Fl.dTATIOX PiiOCKSS names for iviil phnHwuma ati,l lUvu pUys witli tli,. nain.'s ;, tli,. same that makes religions (X'oplrs wcrsliip i,lols instrad .,f tixi.K' their linn.ls „n priMripl.-s. It is easier. A pil-rima-.. t,. a shrine where one may \v„i>i)ip a rafr. a i,on,.. (,r a iiank ol' iiair. an 1 he ahsolved is less troiihle than leadin- an rxempL-.ry life. So that ^^h.■„ the .lu.stio.i IS asked ••Why does a droj) of water that falls upon dust take tiie lorm of a si)here.'-' it is easier to say •■()h. surface tension" and let n tro at tiiat than to think ahout it. It is all very uell t.) sav that a snark is a hoojum, if you first ddine v(.ur hoojum; hut when v(,n serateh tiie Ih.oJuiu an,i lin.l the same old snark the pursuit of kn,nvl- ed>re seems in vain. FLOTATION-TESTS IN SEPARATING FUNNEL PIffect of Alk.m.initv. (From the Mining and Svivntiflr Prrss of .January S, 191(1 1 lOl) iirams of 20()-mesh milllnads, assaying,' An 0.17. Ak 2!t 5;.j frothed t; times in 400 ee. mill-water, with 0.44 Ih. S. 8. oil^ and 0.44 11). eresylie a.'id per ton of ore, at a temperature of 80^ F. r.ime. II]. pel- ton Test At At '— Concentrate-A ssay-^ —Tai ingAs,-ia.\ No. start. end. Gm. All. Ak. Au. As. 1. 0,08 0,112 Acid 17.5(i2 0,41) 90,0 0.12 16.1 A 2- 0.01 Neutral 15..S59 0.00 110.6 0.10 12.4 8. 0.15 15,3.".0 0.S2 164,(5 0.06 5,1 4. 0.25 0.01 A Ik. i:!.470 1.00 192.1 0.06 4,1 5. 0.S4 0.02 14,20 0.85 184.2 0.06 3.8 6. 0.43 0.04 15.05 1,00 166,4 O.Ofi 4.9 7. 0.70 0.12 " 2G.95 0.52 89,3 0.03 6,4 8. 1.00 0.25 " 31.5b 034 60,3 0.09 12,9 In sei)aratory-funnel tests, a.ssays of eoneentrate are nnieh lower than in phmt-practiee, Tailinj,'-a,ssays are praetiealiv the same. When frothing; in mill-water, the hest alkalinity.' i)oth as r.^iiards e,\1raetion and irrade of con.-entrale. is from 0.01 to (1,02 Ih, per ton of water. I-'LOTATIDX I'lUNCII-LKr- :ili( FLOTATION PRINCIPLES \U- ('. Tkukv 1)i him.i, (Fioiii the Miiiiiiij anil Sncntifi,- Pri'ss of 1-Vliruiiry l'.». IDlHi III attmiptiiicr to st:irt u liiscussiou on Hotiitioii liy scttiii.? forth my osmotic hypothesis, tlic main objects were (li to firmly estalilish I'liiidamerital laws ami (ieliiiitioiis and (2) to tiring' out and classify new phenomena. Flotation terms have heen misused and .jumbled ill the .same way that the so-called e.\pcrt makes a mining' report ridiculous by ;',ie use of geolo to entertaining a stranger who might l)e gathering information to be used .-igainst them in one of the various law-suits. As soon as the managers or officials in charge were assured that I was not there for that j)urpose. they afl'orded me ample oppor- tunity to learn everythuifr concerning flotati(m, giving me access to figures and data. In this country, it is .seldom that a C(unparative :i20 Tin; FLOTATION I'liocE.SS ly stnn,ir,.r reeei^ . such cun-t.ous tivatnient as was slunv., , tlir ri.rdial coiniiaiiy officials iliere. At tl„. I'ropri, lary n.i,,,, „ Ikt. ,1,,. Ddprat pr.xn.ss was in .'pcninon. ,,„ .,il ..s I,,.,,,. „s..,|. y.t thcr. wa. pra,.t„.allv tl„. sanu. persistent trot i, as at otlu.- plants usin^ tlu- Minerals Separation process. Ins faet then eliminates the two hypotheses for flotation ■"i^.'"..e,l !,y Mr. Ralston', who says that "The first hypothesis is hase.l on son.e aea,le,nie work ,lone l,y U.uul^s. who dclucea the I'll'-n.cr n.e,,uaht,es as appi, .n,. to . ,,.se where a powder or ""■ P."'tHes ol a e„llni,|. is suspended in a li.p.id to whieh is added a seeond h.pnd that is unniiseihle with the first." There at the 1 n.pr.etar>- .nine, where .".n.) tons p..,- day was heinjr treate.l hv a Mnde -eelL^ no sueh li,,nid was used. Therefore, aeeordinfr" to •Mr. Jialston s hynothesis. iVoth-tlotation .■ould not tak,- plaee Yet the reeonls show that thousiuids of tons of xine eoneentrate has heen reeovered by froth where no oil was used. I .p.ite a^ree with Mr. Judston when he sa.vs "It hanlly needs to he said that here we hnd so„,etlnn,. very elose to the eonditions obtained in ^he flotation '"■' r- , "f" ""•♦• ""■ "''J J-^l'"'"-e hulk-oil flotation method fulfills exaetly fh. eonditions that Keinders had in n.ind." By basing the whole .sub.,e,.t of flotation on ^ra.s oeelusion. a.s I have "done in ,uv art.ele. ^\ hy Is Flotation.'' in the Minin,, a,„l Sri,,f;tir Pn.s o> September l.S. all flotation proees.ses may readilv h, exphdne,! On seenifr for the first time a sinprle spi^zka-sten bein? fed 700 lb "i ".-e per mnnite by means of a 'push-feeder' as is ,lone at the ' mpnetary, one .'an but marvel at the si.nplieify and rapidifv of aet.on of tins froth-flotation proeess. whieh makes a marketable Vi.,e eoneentrate with hi,.h recovery without re-'r-eatinfr. As no oil was nsed, I .su.nmed up as follows the es.sential elements: -;,„ ,„,id md l>'Mt ,n a,idit.on to ore and water. There is nothin- else e.ssential to th!s treatment. Studyi.ig the e(,nditions there, I soon beeamo ••"nyuH-ed that the funetion of the aeid was not onlv to produee I'ubbles tor froth-f.u-nmtion. but also for the ereafion of seleetive aet.mK Sniee tl,. solution uas kept as near the ,.ritieal temperature :{2I fiirM'ti..!! of til,. iH.at? Tl;,. ,-ol,l „iv .In.i.i.in;; into this iiot .solution .•i.m.M M.inr iiir uitli it wiiiHi tli.. ii,.:it cxi,,.!!,.,!. Tiiis was not tl„. cssontial factoi-. Tho licat ckih-UM ..noiitrli <,f Hi,. o,.,.l,uk.(l ^as from 111,.' oiv purticli.s to fonii nurhn for Hi,, attaclinicnt of nasi^ent gas t,i form ti,itatioii l)ulili|..s. Studyin,; tiie Kinior,. vai'iium proc'ss at tli,> J5ritisli Hn,iv,.n Hill plant at a later dati-, I summcl up tli,. ,ss,.ntial ,.|(.in,.nts tlinv as follows: va,.mun ( t,) lilu^rate tlio air- ari,|, oil. and alkali. At a first glaiife it was seen that here was an.itlur m,.thod of making Imhhh.s and froth. This froth wa.s p,.rhai)s nior,. persistent, as th,. .'uwlope for the Imhhles seemed tougher. The dit¥,.renee was so slight that it is liest desc.rihe.l as that hetween th,- froth forme,! , luring the early stage of the clean-up in the aei,l or -eutting-down' tank ,.f a ,.vani,i"e l)!ant an.l the froth form,.,l during the lat,T stag,..s. It was natural. tli''n.for,.. to a.s,sum,. that the j.rineipl,. or ,.au.s,- of this Elm,)re pro,>ess of tl,)tat.on was i,lenti,.al with that ,.f th,. Delprat at th,. rroi.ri,.tary. 1 was tol,l ther,.. aii,l have li,.,.n r,.peat,.,ily tohl siiU'e, that tn,. oil was the ,-an,s,. ,)f the seleetive a,.tion. I newr will lieli<>ve this, with all the i.yiden,.,' against it. alth,)ugli on a,.,.ount of a,lsorption— not o,.,-;a. sion— of ga.s's by th,. ore i)arli,.|..s. ih,.y ar," more ,.a.sily w,.tted with oil than with u;it,.r. Th,. n.sults at tli,.s.. two iinn,.s w,.r,. praeti,.,!lly the same. The gra,l,. of the eoncntrate at the Hritish plant was high,.r. hy r,.ason of m,.,-hanii.al r,.tin,.ment.s, and not th,. ,litr,.renee m i,ro,-,.s.s. Th,.r,.fore the ,)il cmhl not he th,. essential ,.|em,.nt for s,.l,.,.tive aetion, heeause no oil was use,l at th,' Proprietary The oil was an essential element only in that it toughen,.,! the froth. Owing to .,i,.,-luini,.al m,.ans of op,.ration. the froth eouh! n,.t h,. remove,! so ,|ui,.kly nor could it he <.arrie,l in such a deep layer. Then'fore oil was ad,led t,) tough,.n it. Csing },\r. S,.ott's w,.r,!.s^ •■This froth risf.s and fl,)als much tlie same as a h,:ar,i woul,l" while the Df.lpir. huhhles "float over, if we g,.t them ov,.r before th,.y l)r,.ak"': and "if they ,1,1 l,r,.ak, tlu> mineral .Imps and is ,.aught hy the huhhles behnv."' Oil. then. ,.an !>,. ,.!iminat,.d in making the following eom- paris,)n I),.twe,.n tlu' ess..ntial elements of th,.se two pro,.,.s.s,>s. Aeid creates the seleetive aetion as in the Delprat metlux! : lime is tlirn addcl to neutralize it, becau.se th,. va.-uum rna,.liines a.e of ,'ast-ir,ui. A,-i,l was foun.l t,) he n,.,.,>ssary in the Delpr.il process to create the buhhl.s. It ,va.s n,.ce.s,sary for th,..se bubbles to form as th,>y "came into b,.ing" on mineral parli,.les ;is nnejei. \:as.,.(.!!t bn'. !•!,■.; ,..f -.Ar nValter A, S,^ott, counsel for defendant in the case of Minerak Separa- tion !•. Miami. •{22 ■rui: I i.(ii'vTii>\ I'f.'orFss •■!'•' riinritMJ in tlic sjiiii.' \v;iv ^,,il,.,ttL , ■ , ''•"' •'I'vady ;,r|,.,| as p.vvinuslv ,|,.s,.n:H.,l ri, , ii , :;; I ;,,"::,;;;r,:,:.,:: " " '"' "'■■" ■ »'"'" )•■ »« \\\\>n I li,..Mii III,. Ntiidv ,,(• III,. I),. i>.,,. ,,. - y .■'-'. I - a/a J a • . ;;:'r,:V ;■ ■^-'■ "■'■"■ '-;■■ , ■'■"'■ "" "■-■'"«"' '*=««:'.."':;::::r;:;;:'' :^i..',f:.:'.ir:;:,,;;;;;;;ir;;z?--,.i~ ::";;:'::";::';;:;:;,;::;;r:;;:-ir-:- »-v., s n]s: '■Tliri)iiut this ' '> "<'':'!■ ■■"i;l as a ,vs„U. osp,...ialiy aft,^- th,. nili,,.. take "P th,.ir a.ih.suv ai,--fil.Ms aM,| fl„at " Th,n- u..,-. - '•}^'' ;;:;;•;;..-.. ^^..es Who,. I was n,,..... ins„.a.,. h:.' .„::;;: .,:':- . . „„,.„„,n.. ,.„ws .,r sta.,..n.,l „.ia„„.la,. .,hstn.,.,ioMs Th .,..., sh..t-,ro„ ,.„„„s „,„i, „...y w,.n. pen„.n,li,.,!h:: I: s .,. ,,,., , , ,^.^.,,„ „,,,,, ..^^^,^1 ^j^_^^_^ ^. _ . • '^-^ ■^^'- """^■*^'' ^"•^•■'*- '1,.. s„h.j,v,in^. of ,h. .lil ,,„!(, ^•CoBTPnlratiiis; Oivshy Flotation,' l,v Theodore r Hn.^r e , , page 117, ■ '"^"""^f ■>■ H<'0\"r. Spooml cjition, II.OTATION I'HINCII'I.I: 323 to ,-n,„pn.sx,.,l nu- n,;,y 1„. an ,.ss,.,„inl part nf ,|„. np.n.tin,, '• (, -'"'I'HihUHlly ,s. and ihis ..i.th.,,! is ,,,,t,.nt,..| l,v Dudl.v II \,„,,s • altlim„W, opposod hy M\u,-uih Separation Lt.l. wl,.,, appii.atio,, f,„. )iati'iit was made in Kntrlaiid. Tl„. I),. Hav.y float ^s .a„s..,l I,y air. Wl>y is it not a iVotir Norns urns lus sup.r-satnrate.I li.p.id dir-rtly i„,o tli. pnlp-niass ;'■"';' "•"'I' - tonn,.d, Ti,e pulp n,ass at th. A.ual.an.atJi Zino Idant. super-salurated witi, air. wa.s turned on to ,]„. top on. of .arl, srn,.,s ol tour .•on..s, Th.-ro was no eha, for fn.tl, to , n, while siT.a.i.nK ,n a thin stream over the siirfaee of a eone ' io,, however. ,s entirely .litTerent fron, the unstable float on the llen'rv J ood type of n.a-hine. wiueh depends on snrfaee tension entirelv It .s hest desenhe.l in the wonls (,noted from He Havav •'Wh,.,' the oontonts of the reeeptaele were en.ptie.l into a beaker a tiiiek c eanlayer of 'hlaek-jaek' spran. to fho snrfaee of the li,,nid, whUe the white ,-lean -anfrue was j.re.-ipifated to the bottom ••■ t pon studying several plants usinsr the Minerals Separation pr<...ess, the lollowing e.ssential elements of flotation were easilv nvo^n.xabb.air , be:,, in l>y stirrers ,o super-saturation , aeid 'oil rinil Meat. It is to he noted that these are the same as deseribed in the other proee..ses. 'raefeally the only difTerenee is that the froth is n.ore persistent, beeause there is more slin,e with whieh to armor the uW.Ies. i he violent agitation eoa«niates the e.xeeedingly fine metallic pa. t eles ,n the s,-vme way that butter forms in a ,.hurn. The.se eoagules are _f hen aken up in the froth the same as larger metallie partieles As Mr. Hoover" states. '"Large quantities of air are beaten into the i . P i^^ n.nnmg the maehine for a (..- minutes on water alone, it ^^'11 IH. observed that the ,,„a„tity of air so beaten into the pulp is ;;"oi-.nou.s. t,.r the elean water will be milk-white." Tins air .s it comes into being " uses the mineral partieles as nuelei from "whieh to grow into bubbles. The resume „f , be.se eommereial proees.ses is to show that naseent ?as ,s ne.es«.ry. The only explanation of single selective action for ail proeesses is that gas is held in th.e solid particles A theory that will not explain all of the.se processes is of no value wliatever^^ Hoth of Mr. Kalston's hypotheses depend upon the use of *V- S. Patent No. SG4,856, Nov. 19. ]90fi. 19,5''^!:^'S' " ^'"'"'"' "^ '^'"'■■"'^ «• ""'--•"• 'r. .f .. p.. .T„ly u. "Tonrentratine Ores l).v Flotation,' 2nrJ edition, page 1,-ifi. :524 TIIK. KI.nT\Tlu\- I'HdCKss nil. wliicli is iKii JIM cssriitial clrmctit tci tlotiilidii, as was slmuii aliii\t'. Alsii these liy|)(jtlii'ses assume that hitihh's, existiiij,' as sreh in a li<|uii| I)ui|). eaii tiieii have mineral partiel s atta hei| to tlieiii. If tliis he so, anil it is not neressary to <:vi)\y. as it, wiM-e. the iiuhliles from the nascent t;as in the li(iuii|. why is it necessary to lieai air into solution heyoinl the saturation jwiiiit as is done in all fi'otli-Hotation maehines usinjr air as an adjunct except in the Callow machitu' .' It would he much sniipler to turn in a stream from a comiJressor or lilower. If eleetrili- cation is then all that is iiei>ded to produce attachment of the mineral pai'ticles, surely there are plenty of ways tn electrify the huhhles. Thonuis .M. Hains' says, "It would s<'em easier, therefor", to electrify a hulihlc than to keep it from lieinsj; electritied." No; somethinir nioi-e than elect liticat ion is reipiired of the hulihle, as all who have tried to produce a tloat in this manner well know, James A. Block,' ' in his ei'ifieism on my article, say.s: "I cannot see how the water in a • 'allow or- other pneumatic maeliint> can become greatly super-satu- rated." This is hest answered In .Mr, ("allow' himself: •'The hul.l.les eiimposini,' the froth ai'e iOu.-? 0(1 i-'iuiai iuii." i(> .1. M. (\i\'ii.iw . M. a .<. p., Tfec, -*, ir»i;i, liu,• -. »Vol. XXIII and XXIV (N. 3.), Part 2, 1911. Abstracted in Enp. .f Min. Jour., iia.cc .!07, Aur. 12, 1911 (vol. 92), and jiagc 71, .lul.v 13, 1912 (vol, 94). l'I.UI'\TliiN I'UINClI'l.l :{25 minerals tn tloat nr tend t'> Hnat wilhdUl tlic aid nf oil. lie sliuwcd till' clTi'ct (pf frasi's iifiduilrd liy niiticfais to lie il i llic pai'lii'lrs are iKit wholly Wetted when iniiiierseel in water; ( li - the j)articles tend to float when sprinkled on water: ( .'! i the parti of water. It is prohahle that the i.'as lihii imu he ex|ianded for I'einoval in appi iahle ({uantities only in the presence ol' water and that exhaustion in the dry state does not remo\e all the jrji.s present." With a view to further invcslifratinir the jras held hy solids, he condMetcd the followinij experiments: 1. ('upper aihi silver foil were (deaiicd with sodium hydrate and distilled water and dried. These and uncleancd iiieees wi're treated in a \ac\niii)-flask. Ki'\\ huhhles l"ormed on cleaned foil with distilled and air-free distilled water, hut more on the uncleancd. All foil floated in tap-water. 2. Six steel needles Were cleaned in tiie same way as the I'oil and allowed to stand one half-hour in alcohol and then drieil in a desiccator. They would not float on di.stilled water until if had been ex|)osed for .sonic time to the air. Another set of needles and iron wii'e were similarly cleaned, hut would not float until allowed to stand in a desiccator for two days. The sjiinc results were ohtained with sulphides cdcaned with sidphuric acid. "These (>xperiiiients show that jierfiM'tly cleaned needles and iron wire will float on the siirfai>e midles and wire are allowed to 7-einaiii exposed to the air for sufficient time."' 'i. ('leaned and uncleancd j)ieees of iron wire, on heiiifr immersed in a saturated solution of carhon dioxide, showed the following results: (a^l clean jtieees collected very few huhhles, while (lil unclean }>ieces were covered with a frost of huhhles, I have coritlriued these experiments, therefore I aiu j>ositive of :j2 I'Mi: l-l.nT \TliiN rUdCK: till- incnMv.-iiirss ..r Mr. Kicliii Ill's stalfiiirril. '•If ycii |,l,i,r nii onliiiaiy n.rdlr. say. a lao' ihmmIIc suilalilr Tnr iim> with Xo. ,s(i ilm.ail. "" ''!'■ siirlarr ,,f a licwl i.f uali-r, it ^illks at ..nee !■. tlu' iMittcnii. Ill .ilir,|i,.||,T to III,, law (if trravity. If. linucViT, ynu pass ||i,. urrdii' tlirciifrii ydiir liair. s.i that it lircduus trivascd, it will tloat mi the wat.T."' ' Tills is the saiiif nM false as.siiiiiiptii>ii that ml is a lu'ccssity iiistrail 111' an a'd In tlnlalimi. Swiiiliiiiiir and K'nd.irf ' say. '-.X way of d.'iiionstratiiii: tli- pivvriirr of trasrolis . ■ I ] \ , • |o| irs is to sift solllc powdiTcd slllislancf \\liirii easily sinks, sudi as sand or frrrous siilphidrs, ii|>on tlif snrfa.c of hot water. piv\ioiisly fiv.'d from iras hy lioilintr. HiiMilcs of j:as iisr from the siirfaei. of solid part ii^lcs. "' --It spmns niMTssarv that tho LMs slimild lir prodm-rd al tli, ..rfarc of th,- paniidcs tlirms.Kcs." I'll,, air lilm always plays ..n important part; an, I il III'' III'' is ihoi'oiiL'hly wash,., I ,ir lioil,.il in watrr to remove tlic air lilm. ii ,.aiiii,p| h,. roiicni ral,.,| with ai-i,l." Ther,. an. many otli,.)- r,.f,.ivii,-,.s all sliowintr tin' same tiiiiij,': llial till, iiiimral parthhs to he tioatrd must I'oiitain iras so as to ai'l as niii'lei for the iras as il ■•,-oiii,.s into Iwiiij.'" from the iiipiid. Tli,.|vl'oiv. in my former aiiiel,., 1 ,li,l not pres.'iit this ,.vid,.|iee to prov,. ni.v slatem,.nt. whii-li se,.m..i| a s,.lf-,>vid,Mit fart in vii'W cd' tin' pi'esi'lil kno«l,',|i_'e of Ih,. siilije,'!. .Mi,-kl,' rolleeteil j.M.s,.s from eoneent rat,' mail,' from Broken Hill iiialerial some of which i;as i-onlaiiied : I 1 I N . O . CO, {) . CO. . 2 .Ifi It is seen that these fja.ses obey IT,.nry's law. ea,-li ,'\istiiiLr iiidopi'ndent of the otli.'rs and not ilisplaeinfr the othiTs as Mr. lihiek'-' says iiniioiiliteiily \\,)ul,l be the ease. An analysis of a samp],' I'rom the Ilorwood proi'i.s,s fjavo: N O . ro . 1 4 These ttire,' sami)les of pras beeaiiie ilisenprai-'eil from three samiiles "■Wliat Is Flotation?' li.v T. A. Rickard. M. d S. P.. Sept. 11. l!il.-|. iia,£,'e :;s4. ■ r-;:;:r:- :-,:;;: :;;■;;;?;■ mr ; arauaV oOiiti.>, Dec. 12, 1905, "u.v .J. swinimrne and G. Rudorf. Abstracted in Kntj. if Min Jour., Feb. 10, 1906. i-.Ianies A. Hlook. If. if .s. />.. Ott. 'Mt. 1;)1.-,. page li')!*. Ki.nr \i'i(i\ riiiM ii'i.i;s 327 nf iMiicciitriifr uhirli u,r.' mIIuu nl to stand. A Itrrujinl a vaciiuni .■i|i|>lir(| to No 1 saMipir 1 70 >,'iii. sulpiiiilr t;avf a fiirtlicr amount ot' 1 ' I'c. Iras aiialv/iiii.' : ^ 27% O H.l <■<>: 58.8 On liiisinir III'- li'iri|>iTatni-i' lo the lioilintr point and sulijcrtinij this sain])!!' to \ai-nniii, tliiiT was tlii-n t-'ivrn otf >.'J vr. of tjas, vliM-h was t'onnd to I..' pfai-ti.-ally all caflion dioxide i':-oni tlif Xo. li sanipjr h,. oliiainfij Is.:, ,■,.. irjis of wliicli practically all uas CO.. On sulijcciintr miihraN to reduced pressure •■Hid heal, lie I'oiiiid that I oiild olitain iiioiv ir,is I'roiu ealeite and i|ilarl/. This uas mostly CO.. lie proved in all these ea.se.s that the ( '< > , ol it allied was not tVom the decomposition ot' eariionales. This shows that mini lals in t'l'iieral ocrln.le lms. allhouirh .Mr. Iialston' says that '■i^'ood ea.ses ot' o. •elusion ha\e heen I'oiind thii.s I'ar only in amorphous siilistanees." .Mr. IJIoek is ipiite riu'lit when lie says "lh;il it Would he hherated with sul'tieient rapiility to float the particles does not seem prolialilc.""' ■ .\|so .Mr. IJalston' is correct in sayiu!.' "How the ti^'ht ly held t;as eoiihi he liherati^il t'.ist enouirli to com|)are with the exceedinijly short time wlii.-h it takes to ai m- plish flotation of a sulphide particle is ditlicult to explain piiysically. " F simply stated that •'if this jras lie expelled from tliem. wiieii they are in a liipiid. at a time when the ^ras is expelled from the liquid, they heeom.' the nuclei for the t'ormation of "ra.s liutihles." On tiip other hand, if Imlihles are not formed from iia.scent iras of the liijiiid in contact with the mineral iiartici,. there lan he no adhesiiui hecause tile liiihliles art' Surrounded hy liquid lilm.s; or. if the particles contain no occluded !,'a.s. there can he no adhesion liecause the p,articles are siiri-oiinded hy litiuid films. That these two words 'nascent' and 'ocelusion' were olijected to shows the neces,sity of extreme care in the ehoie(> of terms, and I am criad that .Mr. Ralston hroucht ui> this point. 'Nascent' is detined in Wehster's Xew International distionary (."irdi, Ittl'), as follows: "Binnor horn: eomiiior into existence: tieg^innintj to frrow ; coiiniiencin}^:. or in proees.s of, development." The Century dietionary, ")tli edition. 1011. ffives praetieally the same definition as follows: '"Hefrinninp to exi.st or to crrow; eommeneitifj development; cominfj into iiein?; incipient." The following usage is given: '"Wiping away the naseent moisture from my brow: Barhain. 'Ingokisby Legends'." Available gas of any kind for flotation must "eome ;J2« llir. 1 l,ciT \l|n\ riiiiCKSS Ititn Imiiil'" ill lliis u;i\, Mr. r.;iins' caci r,.iil ly .lisiTilirs tlii>. ;is t'dlliius: "ir |inuilirr,| i:,il,n;i err. with a liiiirsloni' LMiit;\li\ he dropped into imrc water, most "( tlie powdiT uill iiniiirdialcly sink t(, tllr linlldlll. As the air cin-losrd liy tln' parlii-lrs is . April.,! pradiially. nnr sirs tln' t'dniiatidii of ■arinori'il' liiiMilis. soini' of wliirh may last fur da\ s. II, ic is Hutatioii wiliioiil oil or ari.j. If nilrir arid lie addod, tlic ;:as huMiIrs I'urnir.l liy tlir artion nf tin- jirid Mil Ihc <.'aii'_'Ur "ill larry \i|i paili'-N's of tralciia "' I liav<> jijarod '. iin'h piir(s of c|iiarl^ iraliiia, and otlicT iiiiiirrals in i\ li.'akiT lillril witli water satnratid \vitli air at ainiosplirri.' pivsMiiT. Tlif purposr was to watrh tlic fMriiialion of tlii' lniliMrs. More sinall liiililil.s formed nil the iihtallie minerals when heat uas apjiliecl. The hiiKhles fni-med on all minerals apparently in the same way that iiMiislnre fnrms mi one' hrow. I wish to ih'serihe this. TlieiM^ is (iiilv one sint-de werd in the F,nj;lisli laiiL'iiaLre that ean he used I,, ,1,, it -misei'iit.' This is n.it "the dissolved (ras that ean lie liheratid."" hill it is the dis,siilved ..'as at the instant of lih.'rati.m. U.^ranlinu' o.'.dnsimi. Mr. I\alst..n has li.en kin. I I'lioiiL'h to m.'ii- tieii three ways hy wli.'h -.'ases .'an h.' held in seli.ls. ami I sli..ul.l hav.' ns.-.l imnv eaiv in the .dioi.'e of the.se terms. I us.mI tlii> w.M'.l ■ hnh.r as a i.'eneral term to denote either siirfi adsorption or s.ilid s..liitioii. As .Mr. K'aUt.ni says, ■■this is a term tin- m.aiiins.' (d' whi.di has heeii nnieli disinite.l." Tryinu' to sh.iw that the >;as in the mineral oheys the sam.- l;iws as the iras in th.- li.piid. as ]. roved hy .Miid<( ^'as whieh dis.snlves in a ^'iv.ii .|iiantity of water is ],roiiortional to the pressur. . and from this exp.'rimental iTsiilt. Van't llotV showed matlieinalieally hy the iirin.'iple of thermo- dyiiniiiies that, when in solution, this same f:as miist ex.rt an osmotic pressur.' ";" and that ' ■ Sidistan.-.'s .lissDlve.l hy soli.ls lia\.' an .ismotic ])ressiire as shown hy \'airt HofT. so we ean sjx'ak of s.ili.l dilu- tions" :''■ also that "the frrenter the ])ressiire t.i whieh the jras is suhjeeti'il. th.' IarUj.'li the lh|iii AH'mmI Daiiiii.'H. 1: 11 Alsii Mr. Ki'kaiii slal^s: "1'iiit \\alcT lias triTat siirfai'c tciisiiiM. it also has no .sii|)iTlicial viscnsily. " N'lscdsily as kiidwii Inclas' is an intiicly (iitVi'i-ciil iifdpcrl y of iiialtiT frdiii that wliicli DaiiiiiiH in Iss.". cdiil'iisril with siirfan' Irllsidii. I'l'i-hajis till- hrsi cji-linitidn nf visi'osity is hy Hai-ry ('. .Idiics.'' as I'dllows: 'We iii'tMJ simply iiicniidn In ic llic udrks nl' I'disi'iiillc. I'aL'liani and liallclli. Sldltf, ( iartfiiiiiiislcT, and 'rfaiiln'"' • • • "Tlif iiidiiiiiiii'nlal wcii'ls dt' 'riidi-pr iV: luidurr miTit iihut carrl'iil atl'iiiidii." • » • ••'I'liry in-dvc cdin-liisivcly. ulial has lucn hinlcil al iMldri', that • • • viscdsity may he 'aki'ii as thi' sum (jf the altrai-tivc fdiccs in jilay lictwrcii tin' iiidli'ciilrs ; • • • I| is, thcri'- rnic, iiiadi' cvidi'iit that viscdsiiv di- inlir-iiidlrriilai- attrai'tion is in fiality a |)rdpirty df tlie atimis dt' wliidi tlif mnli-ciiics arc cdiiipdsrd." This ■supcrtirial vis<'()sit\- ' is well explained in the Hin i/i lnji,i,li(i llriliniiiini,'^ as I'nlldws: "The \aryin iiiiiy he [ireparcd so as to heliave in the same iiiaiiiior as alcohol." ..Ir. Rickard, in his second article, pafje .")17. Miiiiiifi ami Sciiiitific I'nss, Octolicr 2. IDlf). says: •'To make liiilihles. the surface tension of water in the flotation-cell nnist he decreased by a contaminant and at the- same time the viscosity of the li(|uid must he st reiisitliened. ' " As shown alxive, it is not the visiMisity hut the fjeneral surface tension efTect tliat nnist l)e strcntrtlieiied. As I pointed out, a sojiihle or i)artly soluble oil will decrease the surface tension of water hecausc it dilutes the water. which lia.s the fireater surface tension. 15y I'cason of this catise alone, the tendency to float is liecreased and the huhhles luiist '•Coiuliictivity and Viscosity in :\Iixed Solvents,' Carnoyie Iiislitiite, I'li!)!!- ratieu Xo. SO, 1907, pace 19. I'Uth edition, under TapiMary Action." :!:!(i Till-: KLOTATION I'KOfKSS inoru easily, rsi.ijr n \,,liitil(- oil in a M. 8. macliinc. I luive had the imhhles hurst so violently that thr ceineMt floor was hlackeiie.l M-ith zinc suli)lii(le at a distaiu'e of several feet from the machine. At the same time I was makiiif? a very clean zinc eoii.rntrate from Leadville mi.xed sulphides after a Ilorwood roast. As no other contaminant was used, this was only made possihle hy havinj; the tnineral particles well oiled with the thinnest possilile film to aid cohesion in armoring; the huhhles well with the zinc sulphide particler.. lu this case the surface tension was still further reduced hy the sulphuric-acid electrolyte. Most oils, however, aid modem flotation in three ways, as I tried to point out in my former article, hy (1) deerea.sinf? the force of adhesion of water for mineral particles hy fornung films around them, (2) increasing the cohesive force of the mineral particles for each other to aid in the formavion of a network of mineral particles around Ihc liuhhles to toughen them, and (3) toughening the huhhles hy forming films of oil around "' huhhles in addition to those of the water. 'Touglien' is not a good word wherehy to express the meaning Mr. Ralston explains this -ery well and at length on page 624. Mining and Scioitifie Pre.t.t of Octoher 23, IHlo, under his inter-facial tension hypothesis. He clpims, however, "It is doul)tful if the air hul)l)les could he completely mciitled hy oil." Tliis is contrary to the experience of others. The colors on the huhhles indicate that they are mantled." This shows that Mr. Callow is right when ho says "Tlie huhl)le-maiitles in a flotation- machine are nndoulitedly composed of oil, or oil emulsion."'" The sum of these tension effects causes persistent huhhles. even though the surface tension of tlie water has heen reduced. TheEe iindonhfedly arc extremely thin films, at least approaching one molecule in thickness. Therefore molecular forces must he taken into account in dealing with them: as :\rr. Kalston says. "The underlying cans*' of the tensions and of electrie charges is the same thing — some strange molecular, atomic or other force manifested in 'adhesion.' 'cohesion,' or even 'gravitation,' if you plea.se." Tn dealing with *hcse inter- facial tensions, the drop-weight method cited hv Mi roghill"' for determining surface tension is of no value to flotation. The inler-farial hy,(othesis of Jfr. Ralston explains very well indeed the jjcrsistency 4. •-"'Surface Tension.' In- Will II. CoKhill. M. a K. p., Oct. 9. 19i: page .543. FLOTATII )N- I'KIXCII'LKS 331 as IS Mr. Bl„ck,'' who says, -T. J. Hoover, for instance, in his book, 'Concentrating Ores l.y Flotation,' presents a consistent theory." Mr. Hoover (2n(l edition, page 72) savs: "There has been no satisfaetoiy theory yet propoinuled as to whv acid does promote the preferential a.lhesion of water to gangnc particles." Kven the lat.^ electrical theorj- fails to answer all the questions asked by Mr. Hoover, on page ]00 of his book. I answered tlie above question in my article by showing that an acid or anv electro- lyte creates osmotic pressure, by tr>'ing to enter the solid particles ot which their surfaces act as sentums. If this pressurr be sufficient to drive most of the gas out from the gangue particles, the metalli.- particles can be floated, for the reason that there is still left suffiei.^nt gas in them to ecome nuclei for bubble formation bv the nascent gas of the liquid. As shown by Mickle's experiments, mentioned above, there is more gas in sulphides than in other minerals and it is held more persistently in the sulphides. Thus a selective flotation is created. I have confirmed these tests. P:veryone who has e.Kperiraented with flotation has seen how too much acid will 'kill' the float. That is, ihe greater osmotic pressure drives f:e air from the metallic particles as well as from the gangue particles. This etfeet is not to be confu.sed with that caused bv substances such as tannin or saponin mentioned by Mr. Callow'" as colloidal impurities or volatile oils and the like, which destrov bubbles by reducing the surface tension to the extent that the gas pressure from within breaks or even explodes them. This weakening of the surface tension by a colloid is an entirely ditferent phenomenon from that shown when the osmotic pressure is increased by a crvstalloid "The crystalloids when dissolved in water change in" a marked degree its properties; for example, they diminish the vapor pn'ssure lower the freezing point, and reduce the b.iiling point."-' And as Dr. Lupke- states, the four laws in speaking of dilute solutions, are " Kquimolecular .solution:; of anv substances, prr,,ared l)y using equal w,.ights of the same s<3lvent, exhibit equal osmoti,. l)ressure. equal relative depres.sions of vaponr-pres.su re, equal risings of boiling point, and equal lowerngs of freezing point." -i-Text Book of Phvsios.' by J. H. Povnting & ,1 .1 Tlioiniison, 3rd edition. ==The Elements of Eleetro-Chemistrv.' by Robert Lupke, 2nd edition, 1903 eaRe 119. :]:V2 THE FLOTATION TKOCESS III iiiaiiitaiiiiiif? that osmotic pivssure of an cli-ctrolyte is tlio oaiise of Sfl(Mtivc tlota i n, it is well to look into the motive power ol' osmosis. Kahlcnht-rir-' states it ''lies in the speeifie attractions or atHiiitiis hetweeii the li(|iii(is used and also lietween the latter and the septum employed. These atKnities have also at times heen termed the potential energy of solution, etc.; they are, to my mind, «ssentially the same as what is termed 'chemical affinity'." Or, as F, II. Carrisou-' put Tauhe's theory: "The drivinj^ force i!i osmosis is a sui)erficial (or inter-facial) pre.s.sure ohtaine.l hy snb- tractinsr the surface tension of one fluid from the tension of the fluid into which it ditf'nses." Or asjaiti as Van't Ilotl" and his followers contend 'Tlie molecules of a dissolved substance e.\ert the same pressure against a semi-permeahle membrane, during osmotic l)roces.ses, as they would e.x( rt against the walls of an ordinary vessel were they in the ga.seous state at the same temperature and the same concentration."" Since these authorities do not agree on the motive force of o.sinosi.s, investigation must rest for want of further data. However, all tiieories of flotation, be they eh'ctrical or otherwise, must come to ostnosis for their solution. This is not to question the fact shown by electrolysis that every atom of matter is capable of uniting with a deKnite quantity of electricity. Nor is it to question that corpuscles (later termed electrons by Dr. Stoney i do not revolve around atoms wliicli are thousands of times larger. Hut it is to question any hypotliesis that does not take into account the fact that particles will not float when all the gas is driven from them. Osmotic pressure can fn.- particles of their occludeil gas. Whether osmosis is caused by electricity or whetlier a etirrent of electricity is caused by osmosis has no bearing on flotation. However, in l>assing, it may be of interest to mention that Dr. Robert Liipke, in his liook. 'Elements of Electro-Chemistry' devotes Part III to "The Osmotic Theory of the Current of walvanic Cells.' As mentioned above, extreme dilution of the electrolyte ;itTects the osmotic pressure and selective flotation. AVith complete dis.socia- tion. as Arrhenius has shown, the ionized molecules are free to obey electric forces. It may be freely granted that air driven from a particle by osmosis may eflfecf a change in the 'contact-(ilm' mentioned by .Mr. Callow and leave the particle negatively charsred. so that it \\(iul(l sink as descrilK-d by him. Also it is grant'd that = <'A Note on Taiilie's Tlieory of Osmosis and Altiartion Prrssnrc,' l)y F. H. GaiTison. Ann.v Meiilral Museum, Srir»rc, vol. ^2, 10li». puKc 2><:!. ir.()TATI()X PHINCIIT.KS .{33 the mineral particles are all either negatively or positively ( ?) ••harged. Assuming the eleetrie eliarges. there th.'ii enters the important qiiesti.iii mentione.l by Mr. Callow in siating his tlieory that •■the partieles possessing them will migrate when plaeeci in au electric field." There is no question but that with an eleetrie tield, flotation can be produced in such a manner iis described liy Hotiie Scliwenn in his ■Khvtro-Osiiiotic Pnx-ess'--- as follows: "ily inven- tion consists of adding electrolytes to the liquids containing the substancc-s to be separated, the nature of the electrolyte depending ujwii ,he character of the substance. If the latter is of sur], a character that they would be deposited by the electric current on th,. cathode, idectrolyte of acid character are employed; and if the suljstances would be deposited on the anode, elect'rolvtes of basic character are used." Speaking of finely-divided substances, some- times indifferent to the a.'tion of an electric current, he continues: "I have found that such substances can be made electricallv active by causing them to absorb [here ustnl as defined by Mr. Ralston] colloidal substances of a .strong electro-i)ositive or "electro-negative character." Of the recent electrical theories advanced, none explains lu'W this imix.rtant electrical field, mentioned as necs-sjiry by Mr. Callcw, IS created by any flotation niachine. Mr. Hlock-" shows this on a clay machine. After selective flotation is created by osmosis, it matters not whether the particles be spoken of as being held together or to the bubbles by electric charges or by cohesion and adhesion in the way I mentioned. Sir Oliver Lodge,=' after saying that "the force ot chemical affinity iias long been known to be electrical" goes on to say that "there is another kind ,.f adhesion or cohesion of molecules, not chemical, but what is called molecular. This occurs lietween atoii.s not possessing ionic or e.xtra charges, but each quite neutral, consisting of paired-off groups of electrons." However great this attraction may be. the mineral particles will not adhere to bubbles already formed, as was sliown abov; but, using them as nuclei, the nascent gas will form into bubbl, s to float them. Such gas formation is excellently described by Duhem^' as follows: "From this, a bubble of vapor will luv^-r be iormed in a region where the "U. S. Patent No. 99.'?,SS8. 2«'Notes on Flotation.' Discussion. Bulletin A. I. M. E., Dec, 1915, "Chapter If,, 'Nature of Cohesion.' in hook 'Electrons,' bv Sir Oliver Lodge, P^inclp.^l ot the University of Birmingham. ■-'s'Thermodynamics and Chemistry.' by P. Uuhem, 1903, Art 275 page 366 334 TIIK FLOTATION ruOCESS li(iui(l is continuous; in fart, if sudi a hulitiii- could licgin to form, its radius would be at first intii'licl.'- small— less than the limiting radius of which we have sjMikcn ; whence, instead of contiiming to Kn>\v, it would collai)sr." On the next pajre be continues: '-These considerations do not api)ly merely to boiling; they completely explain a trreat number of phenomena." The eleetrically-charged mineral parti(des may aid in bubble formation allhoujrh they cannot effect attachment of mineral particles to l)idibles already formed. Regardiner this. Dr. Thompson=^ says that ••the char-red partitdes act as nuchi aroun.l which suudl droi)s of water coiiden.se. when the parti-des are .surrounded by damp air cooled below the .saturation point." "Experiments were made with air, hydrogen, and carbonic acid and it was found that the ions had th.- same eharge in all the ga.ses." ■ Iso, "Thus by suitably choosing *he super-saturation, we can get the cloud deposited on the negative ions alone so that each drop in tne (doud is negatively charged." Elcctrieity may manifest it.self in various way.s, but flotation cannot take j)lace witliout na.scent or occluded gas. =o'The Atomic Structure of Electricit.v,' Chapter 4, 'Electricit.v and Matter.' By .T. J. Thompson. Lectures at Yale, May, 1903. TilK ELECTKO-STATICS OF FLOTATIu.V 335 THE ELECTRO-STATICS OF FLOTATION By F. A. Fahrenwali) (Piom the Mining and Scientific Press of March 11, 1916) The .levlopnient of every nv^^■ n.etallurgieal method is a.co.n- panie.l by a host of eontradietory statements and widely ditferiiig "Punons, but it is only by the eliniinatio.i and correlation of parts of recorded observations that a particular process approaches a state ot perfection. Tiie theory of flotation has called forth a number of articles, eaen writer applying a ditferent hypothesis in explaining the puzzling phenomena accompanying the process. Of the various hypothes..s thus far advanced only two are based on pnnciples of snfKciently apparent soundness to warrant serim.s con- sideration. The first of these inv.,lves the physical surface phenomena that may produce an inter-facial tension. This ha.s. until recentlv been accredited with more importance than all tl,c other explanations combined. The second is called the electrioal theory. The part that surface phenomena may i)lay in linking tiie particles of ore to the bubble-carriers is ably outMned by 0. C. Ralston, whose- trea inenf of this phiise of the question includes reference to about all of the theoo' that ha^ so far been found applicable to flotation. VV 1 hout doubt a proper application of the laws of physical chemistry W.11 disclose fundamental principles upon which this'process may be based,, and it may be in the field of colloidal chemistry that most in- tormation is to be gained. With reganl to the electrical theory, however, fher« has been applied a number of laws of electro-statics that, from the general nature of conditions under which flotation is carried out, would seem to be inoperative. This hypothesis has been tolerated by Mr. Ralston.^ if is strondv advocated by J. M. Callow\ while Thos. M. Rnins. Jr ^ ..x.-Iudcs all other theories. These three references .'ontain I he gist of all arAi nienfs adva n.v d in support of this liypothesis. and the In.st of then, Of t'hrLor""""' ''""'"'■ '" ' '■ "■' ^"''^'- ''■ ''''■ «- "'- -.0 17.. •T, p^, r!r '■'''•'^- s^«-'"^p'^s<' 231 Of this book. -The Eler.nral Theory Of Flotation.- .U. .(.S'. P., November '7 nr, an,, December 11. 1915. See also pa^es 225 and 25S of th . boo) ;};{() Tin: FLOTATION THOCKSS HaiM.n,t...s an.l .Irlinitely I'ormulaf.s th,. ,„.cr.vsMry miui.vnont.s lor Hotatin,, l,y el-.tric-al means. It is my ohject to attempt an analysis of the vanows arfrui.ients a.lvaneed i„ swj.port <,f li,e eleetrieal tluM.rv ami as the only diflVrenec between this an.l any otlu-r theorv li.-s in th," piienomena that cause the bond betwe..n tlie Hotative mineVal an.l tie linbble-earner. it is understood that only this i)hase of tiie pn.eess is under disc-ussion. Jt is neeossary. howev.r, in order to arriv at praetieal eonelusions, that this qu.^stion be eonsi.lered under condi- tions Mnidar to those encountered in practice. Before proceeding to a discussion of the electrical theory of flotation It will be necessary to point (.ut briefly a few of the facts of electro-statics upon wliich it is l)ased. A. The production of electricity by friction is a common phenom- enon; almost any two bodies become electrified if they are rui)])ed together. In the case of .several substances, considerable force is tlien necessary in order to separate them. ..tfractioi, or repulsion also occurs when an elect riHed body is brought near bodies that have been sulgected to friction and if thes«? are light enough (as bits of pitch feathers, wood, paper, etc.) they may l)e lifted. Bodies mav also become electrified by coming in contact with other bodies that already carry a charge. In this ease the first body receives electricitv of the same sign from the charged body and is then repelled. B. Bodies that when electrified at one point are immediatelv electrified all over arc called good conductors; tho.se over wliicli the charge diffuses slowly are poor conductors. All metals, manv metallic ores, graphite, ordinary undistilled water, and arpieous solutions nf salts are good conductors. C. If a piece of metal, or other conducting material held in the hand is rubl)ed against a non-condu<'tor— say, a piece of dry flannel- only the non-conductor appears afterward to be electrified. The reason is that the electrification produced on the metal spreads over the hand, arm, and body of the e.xperimenter to the floor and walls of the room. If, however, the conductor be insulated, the degree of its electrification cannot be increased or decreased. D. By wliatever process a body is electrified there is always an equal amount of electricity of the opposite sign, which may reside upon the walls of the -nclosing room or upon some otlier surface in- sulated from the conductor. Bodies carrying opposite charges, when brought in contact or connected b.v .1 conHneff.r hanr.m.- .?-:=...! 1 itralized. than the other the system takes on the sign of the excess charge lire THE KI.KCTKO-STATICS OF FLOTATION 337 K. It' those liodics iirc stronply plcctritiod. discliarfrc can take place tlirnueh an apprccial.lc thickness of non-oondiictiiit? material, such as air, (lil. or glass. This discharge is facilitated by the presence of sharp projections npon either hody. V. (a) The space between two charged bodies is filled with lines of force that tend to move a contained body in the direction of the local lines of force leading to the surface carrying the opposite sign. (b) These lines of force do not penetrate the surface of the con- ductors forming its boundaries and a hollow conductor is electritied on its outside or inside surface only, depending upon whether the oi)posite charge resides upon one contained without tiie sphere or upon one contained within and insulated from the shell. In the latter case the entire field is contained within the inner surface of the sphere, and in the former ease there is no charge witliin the h(>llow I'onductor. G. The force e.xerted between two small charged bodies is given in the equation V= ^, in whicli q and q' are the charges in electro- static units carried by each of the two bodies, and d is the distance between their centres of charge.-' If the bodies are separated by a iiu'dium other than air a factor K. known as its dielectric coefKicient, must be used, and the equation becomes F =rr - . -^ k d- ir. ]\Iatter itself is not acted upon by an electric force, which acts oidy between different (luantities of electricity. When a conductor is introduced into an electric field it represents a gap or an interrup- tion of the lines of force, resulting in an electrification of its surfaces only, that part i)ecoming positive which is presented toward the nega- tive hounilary of the field and the reverse. In other words, the original field is divided into two. This s;imc effect is produced in the case of a poor conductor but to an exceedingly sniii'l degree. This explains the attraction of small bodies by another that lias been electrified by trictioii. in which case electrification by influence precedes attraction, and what is really observed is attraction between opposite electric charges. Before considering these fundamental laws of electro-statics in '•onnccfion with an exi)laiiation of flotation phenomena, it mav be .. 11 . ■ 1 , , ,. . ... _ luiuliiiims under wiiicii diitereiit plias<'S >f this process take plai •■■The force exerted hy a cliargcd spliere ai ts as if originated at tlie centre. ;{;38 ■IJIK 1'I,(JT.\TI(|.\ l'IiOC'KS8 _ Of first i.nportam'e is tl.e fact that all openttion.s are earri..d out u abk. that, alter any f^nnding pnH...s,s has 1,..., applied in maehines such as arc co,>un..nly us,.!, the indunlual positively char.-cd particles of ore s ould not have co.ao in contact with negatively char,,' h„dies ami ^^,h conduct,n^' parts of ,M-in,lin,^ and nnxin,^ machinery, even 't od has heen added in a prclindnary sta^^^ The ore parth'les arc -'. uctoz., the oil is a non-conductor, the huhhh s are filled „i,|, non- ;;;;;;;';:;;;;''- ""• *""' "'^ f^''"f^>"^ f- -n.,.osed of non-eonducti.,g Tl.ese conditions hcinj; ^ranted, tiic next step will he to apply the aws ol electro.stati,.s to criteria for flntative conditions accniin- to he eleeincal thcry. as su.nn.ari/ed hy Mr. JJains. TIh.s,. inch.de ti:e man, nha.s of Mr. Callow-s article and of the th.'ory in ^^.neral so that a d,s,-uss,on of these in onier uill aj.ply to the Various „ther firticles advanciii",' a siiiiihir hypothesis. J. ••Ores containing valuable n.in,.rais or metals that are -ood conductors are tl nly ones that are suitable fnr flotation " This se<.ms in -encral to be true, but the ratio of flolative tendency to conductivity „f the dilVcrent .uv eonstiluents is nothin- like a constant. For .n.stance. the conductivity „f pdena is to the conductiv- ity -d chalcocte as .'JS: 1. Their ri.tative tendeucies hardly bear this I'atio. I" 'nliie (opposition to this supposed requirement I found that suiall luces of ,l.amond attract a irreasC^ or nil coatiny and attach to liulibles (piiti> as readily as does galena. 2. '-To buoy these conductors, it is n. cessary to supply enough Pleetnlicd bubbles from below to float particles of the conductors that are attractd; hence the smaller the bubble. th(> better the result the amount of i I with eiielo.seil ehargeil eoinliietor insiihiteil from it. and carry- ing an opposite i-liarp'. The eliar^es would he equal and the amount ^.'(iverned hy the eharfii' on the inside sphere These eharf^es heinf? halanccd, the huhhle system eould have no influence upon a hody — charf,'ed or not — witiiout the outer sphere, such as a particle ,nir..s tli.' ..(piat IL'.'JO "'■ fi.ssumiiif,' the ..|iarg..s to be .liam..ter w.nil.l b.. about .",.2 for force b..(.om,.s 52 (dynes bnlan..<.(l Q= = 6715.92 Q =^ 25.0 e. fr. s. ..le.tro stati.- units. Its ir IS not lik,.|y tliat a jiartu-le of ore or a bubble of the nature .nveii ••an have a charge of this magnitu.ie. for (he rea.son that a ,).,tential of Hns intensity w.ml.I dis.-harsre thr.m^'h a very siron- .li..l..,.tric. E.xi.rrimeiu,-. iuiu- been carried out tliat give ratios for el..,.tr.,-static nnifs. potentials, ami .lisfan,... throufxh which .liseharge will take ida...- Tin: i;i.i:cru() siMics hk ii.oi- vtihv 341 K!( rtro-statlr units. IC.l S4.7 Volts.it (lis chaiKf iiotciitiiil. 4s:!0 ]»iS90 2r)-t04 Distance lictwcin laili(le (>[' iralciia would he so iiiteii.sc thai it wouhl (lischari^e throiif:h a dielectric a.s .strong; as air at tiie distance hy which the centres of diarires arc sef.arati'd. Xdt .sjitisficd. Imwevi^r, with tiiis ai)|iareiit theoretical dLsjirovai of the electric tl ry [ undertook a series of e.xperiiiients' tliat .should serve to check the varicius points in the ahove theoretical discussion. Xo. 1. (ialeiia ore was ^'roulld in an a^ate mortar and |)oured from ill! airatc spoon (to prevent discharsie of jiositive elctricity. if present, from ore hetween two [ilates of an electro-static mai-hinc. The ma- terial was derieeted as shown. I'lates were eleetrilicd almost to dis- charge point. This shows that pilena liround under iiisiilatiiitr eon- ditions carr'is a <-liar";e and that a parti(de of this nature. :ius|)cii(led in a iioii-cnii(hi,ti,r in an elcetro-statie field, is attracted. Xo. 2. Ore wa.s frronnd in eonduetiiis of ii. eell. (Mass was 1 mm. thick and separated hy 2 em. Potential he- tween plates of maeliino was S.")00 volts Deflection as .shown, The interposition of glass had very little etVeet. Xo. 4. As in No. :{, hut the cell was full of water. Used conduc- tivity, tap, and aeid water. Xo deflection. This indicates that par- ticles charged, or otherwise, suspended in a eondueting solution (i. c. eiudosed within mir hypothetieal eonductiiiL' -pliere) is not affected hy eleetro-statie forces without. No. ."). Cell contained ore and nitric acid .solution to generate ga.s. Xeifher liul.hle ri.sing or ore particles dropping sliowed deflection. Potential. 10.000 volts. The conditions here duplicate those of No. 4. No. »;. Ruhhles hlown through canvas into water or acid solu- tion were not deflected. A charge of huhbles flowing in one direction •Tile wiiicr is ,m-eaiiy iiideiitea to the (leiiartnu nts of MetallurRica! En- gineering and of Pliyslcs in the Case School of Applied Science for laboratory facilities and apparatus i)laced at his disposal in carrying out these ex- periments. :}42 IMl: I l.ip|\TI(lN- I'ROCTSS WonM pn,,Iu,.,. an ..l.v.n,- nnw.MU. and ,.v,.Mr HH.y ...,.,. ,.l,a,.,.,i ,),,.v '•HiKluctiiii: iiial.-rial. —Ti lJ ~0 F .•■ 'i rial FlC i ^■^-y Alt »V'r^ - CHAffrrBD P -f /T - >c L. E S Fkj. 79. , , ■■ ,^';^"j^°"'-"' ""« f<-^ll containing gasoline. Th-re seemed h ,H ^''f \^.i'^«'^^-*-"- lO.noO volts between plates. Con,litions here should not ditfer greatly fron. those of No. .1 Solut ,^a^ not havl been sufhciently non-condtietin". iiii. i:i.KciH()-.s-i'ATics DC ri.oixiroN :j4:| No. .S. SolutKiii nl.icd in cl-Ttrnlytic ,rll. .-uT.-iiiu'.d us shou,,, ^rav iM. .l.^Hcotiuu „f „rc or InhhU- .Niti, coiKiiictiii^' ,„• iiou-.'oii,|ii,ii„^ so- liilion, Holli icns ati.l chaa'cd c.illoi.ls in-v swsccptil,!,. t„ tliis irrat- m'l.t, 1111(1 no (loiilit they would mov.- fasier than tho lari;.T 1m jy an,l so lessen the potential on (he larger niasx.s. No. !t. Tile \v;it, ,• itsrlf was eleelnily/.eil to fiiniisli (.ms. A tun- way switrii save either iiy.lroK, n or oxygen at the l.oliom poh, uhidi was eovere.l uith a layer of ore. Both gases .-arriea apparently e-pial iiMi.Mints of ore and with e.pial readiness. Hiihhles in either ea.se, upon linking the ui)per plate, did not diseharge their luirden of ore, no matter what the sign of elect mile. No. 10. S<.t up as ill No. ;t, exeerit that s, s was furnished l,y action of nitrie, acid on ore. ( •haniriug of siirn produced no discernihle etreet upon buhblo or ore or upon huhhles with load when eoniin^' in contact with upper electrode plate. r wish to point out the fact that tliis .iis<'iis.sion and these results are to he eonsidered only in connection with the h.,n.: between a bubble and ore particles. The eondition? ehosen have Ixui ideal, in ord.-r to isolate this particular plia.se of the problem. Particles of ai>preci- ahle nia.ss f+200-mesh) have been u.s<>d. but this permits of an eleetro-statie eonsideration without interferenee I'rom exat^'erated .surfaee conditions due to smaller bodies. It is po.ssible that an "ionized solution does not behave like a .solid metallie coiiduetor toward an eleetro-statie eliarge. but I know of no evidenee to the contrary. Very little is known regarding eontaets betw.-en solid-liquid-gas phases, but it is (buibtful whether eharges sueh as ,. ■company phases of a colloidal solution are of much influence in the ca.s,^ of bodies of the ,size herein eonsidered. It may be found that the oil-water emulsion or the oil- films intrr.duee the colloidal element, and no doubt many of the slimes contain colloids, in which the electric charges are of gr..at importance. It is known that masses of sulphides, sueh as galena, are positive, but Assiime edge of ^^^^^^^ '^"^•^ *" *"' NiiMber of cubes. SurfacP. 1 cm 1 i ») cm. "•' " 10' fio •• "■01 •' 10- coo ■• 0-"01 " 10' 6,000" 1. )nct " (one micron (u)) m" (1 sn m n.0005 " (size of nartiolrs In W.inlin susppp^ifini 0.00001 = micron iq.' rq ., .. 0.01 micron (limit of ultra-mirroscop.v) . 10" 600 " " 0.001 ■' = one millimicrn fniii)... 10" e.OOO " " 0,1 mu. = hydrogen molecule lo" €0 000 " " 344 rilK I'LUTATIOX I'UOCF.t.S fli.'s,' same suVlu'l^.s ui .•..ll„i,ial fonu aro ii.'gative. Metals in mass and as atoms aiv ix.sitiv Imt these also as eollaids are negative. This eomplie.ites cr.nsid.rahiy the eleetrieal theory in the ca^e of pulp containinsr l.oth sami and slime. It may he interesting to eall attention to the enormous increase of surface produced hy .suhdivisinn, in which <-asc [.jicnomcna that are purely superficJMl are greatly ..nhanced. AVhen it is considered that these small particles contain the energy iieeessary to subdivide them, whether electrical or otherwise, it is appare-it that i)lien(,mena . ncouiitered throughout a range in size of particle iiody will not h.'ar a dit t ratio to its mass or constituent material. A consideration of this phase of the suliject is, however, without the s.-ope of this i)a|.er. wiiicOi is only given to point out a few of what would ai)i.ear to he iiii,sni)i)lications of H,,. laws of electro- statii'M. ON THE SCIENCE OF A FROTH By Wii.i. IF. ('()(;iiu.i. (Fioni tlir Miniii;/ and Srinitifir Press of I'>!)riiary 2(;, lOltl) 'I'll'' paragraph .,n tli.. character of froth in Mr. Callow's article in the Mniim, ,iml Sri.ntijir I'n s, of December 4. l!tl.-). page S.")!', I^d me tu ,-erer to .some not, s that have been pigeon-hole'id tilm this is not true. R,.ferenee to a recent arli.de' sh.nvs that the moasure of surfac<. osion is not when the lilni br.'aks but at the 'T. A. lii surface energy will be reduced if th.' concentration in the .surface layer is Iow.t than that of the bulk of the solution. This ditference in concentration between the surface Ia.v(.r and the bulk of the sfiiution is called adsorption and is a physical fact. The fjictors tending to produce adsorption are opposed to th" factors tending to establish uniform concentration. The final dis- tributi(wi of a solute is the resultant of adsorption and two other cfTects, namel.v. osmotic pressure and electric charsje. Important qualitative conclusions are drawn from theoretical considerations already developed. A small quantity of dissolved substance may re- r ♦o a small cNtent; the "oneentration in the surface layer is accordimzly ox THE SCIENCE OK A KROTII sNiallor than ii. the bulk, and the etlVct of the solute is thus partly ••ounteracted. On the other hand, many organic salts reduce surface tension^ and therefore accumulate in tiie surface layer; so that in .xtreine eases, the whole of the solute may be eollceted there and pid.lu.v a considerable elTect, although the absolute quantity may ho exceedingly slight." Adsorption is of such unmistakable importance that we will refer to 'The Chemisti-y of Colloids' by AV. W. Taylor for a different perspective of the same thing. Here I quote freely, for I am not intending to advance my own theories but to l)ring out wliat seem to me to be the pertinent physical facts. And here I wish to state that I fear that the premi.se for my recent calculation" of the carrying capacity of the surface of a liquid is not correct. It was an attempt to elaborate on a weak statement in a text-book and hence the calcu- lations themselves cannot be credited. Adsorption, in its most general sense, implies the unequal dis- tribution of substances at the boundary between two h»tcrogeneous phases: solid-gas, solid-liquid, and litjuid-ga.s. We are concerned just now with only the last. The surface layer of a liquid is under great comi)ression due to the ■great difference of the molecular forces on the two sides of the inter- face and consequently the concentration in the surface of a solution must be different from that in the bulk of the liquid. For just as unequal temperatures in a dilute solution cause an unequal distril)u- tion of the solute, so from the same law unequal pressures nuist also produce an unequal distribution. This pressure (due to surfac >• ten- sion) always, in time, adjusts itself to the miinmum. for a component which lowers surface ter- n is always increased in the surface layer whether the component be present as solvent or solute. We now hav(> a new princii)!e to apply to a bubl)h'. to wit: on account of adsorption a fresh surface always has a greater surface tension than an old one; thus if -t is stretched locally by conditions tending to break it. it is automatically reinforced at that point. Tt is now obvious that without adsorption it would be impossible to realize a variable surface tension, for if the solution were contam- inated uniformly throughout, a fresh surface exposed by the stretch- ing of the film W(mld have the same energy ps the old surface and the ultimate result would be idcnti.'al with tlie case cited where pure water w.ns used- In this argument I have assumed that the contaminating sub.stMuce •Page IBS. 348 ■I'm; KI.()T\T|il\ I'KdC-KSS .s s.,1,,1,1,. i„ water. 1 n-alize luUv tl.a. many .,f ,h, H,„aii„„ „ils are "'""" '"' '"^"l"l'l" in ^^iit.'r. liut I luauitain ,i,at snl„l,ili,v is onlv '■•■'^'"■'■- •'>',! lurthrr, we knew nothin- „1„„„ ,|„, .....itii.li.itv ,,V ;'l'"'""--'l >va,-t:nn.s po.ssiblr in a pulp wlm-l, niifiht release conta.ninat- Uig substances that w„ul,l ,,nHluee the adsorption pheno.nenoi. If frraphite, lor mstanee. acts as a iVotliini; a-ent, it niiirj.t have to be "■<-te,l as a sperial ease an.l eonl,l not l,e taken as proof that tlie above arguments are invali,!. If the flotath.n .m1 is eNtrernHv insoluble 'M. an,] l.jrl,,,.,. than, water there would be an o,l tilni at the liquid- ""• I'lterlaee and ovrr the li,|nid til.n eontainin- adsorhe.l oil Ft inisiht be well at this point to ,lrop the subjeet of variable surfaee tension and undertake to p.f a better i.lea of the absolute value of these torees. One physieist has spoken of tlieni as beins: -Tl,.. bul,-,)l,.s • * b,.i„s; prpn,.rat,.l un,i,. a hv,lraiilie pressure varying from M to 4(' im^hes, on risin^r abov,. th,. wat..r * • burst by r.'ason of the lower snrronmlin- atmosph,'ri,' piv.ssure " Plus pi,.|uivs th,. ,.m,.r a bla.l,l,.r when siid,lenly inHat,..l by inerea.s.-d internal, or d,'erea.s,>,l ..xt,.rnal, ,,res- sinv. and is a mi.s.-on,-eptioii. T., mak- the steps more simi)!,. w will Mis; .•,i,|,i.^ iiii. biihbie in air and then when .submerfjed. .\s.sum,. 1 e,.. of free ;.•• triken in form of a sphere ox THE SCIENCE OF A KKOTII ;J4!) r== 0.620 fin. Now suppose tliis air lo hr t'liclosfd in n liquid film in air wlit^rc tiie liquid-air surface tension is 70. Tiie new radius can he calculated liy the ap|)licatioii of H(iyh''s law. which is. that tli.' pressure varies inversely a.s the volume, where ahsolut.' pressure is of course under- stood. The free air is. in round nnmhers. under a pres.sure of 1000 pm. per sq. em. ami a surface tension of 70 dynes per cm. exerts a pull equivalent to weiirht of a|)proximately 0.07 pm. per em. of length. The proportion used to ealeulate the new radius is: 1000 : (1000 + "_:'■"') :: 4.2r^ : 1 (4) 42(Mir-' + 1.176r=r=100U r = 0.61!» ,,_ 4T 0.2S ^ — r 0.i;i9 — 0.4O.5 gill, per sq. cm. The second term of equation (4) is the only one that contains a function of surface tension, and since it is of such small numerical value, it is plain that any variation df surface tension has very little to do with the radius of an individual huhhie in air. Even when the surface tension varies between zero and a maximum, as in (3) and (4), the change of radius is, in fact, too slight to he calculated on the slide-ruh — only from 0.f)20 to 0.61 r» vm. It is interesting to note that P has a value of 0.4r):i gm. per sq. i-m. which equals 0.006 Ih. per sq. in. This is the order of magnitude of the forces that cause a spray above the froth. Xuppo.se again that the bubble is 1 cm. below .surface. We then have : (5) 1000 : (1001 -f "J^ )-=4.2r' : 1 r=: 0.618 Total pres.sure 1 + 0.226^1.226 (gauge) Finally take a depth of 75 em. (61 1000 : (1075 + 2Ji_) :: 4.2r^ : 1 r=. 0.561 Totnl nro-iRure =^ 75 -I- 250 ^^ 7^, 9^.0. Z .-ra-.^ .-?.-. Ihcse result.sare shown in the appended table: 350 THE FLOTATION- PHOCESS OM; ( L liU LhMI.MKTHE HIKK AIH No. Description. r p ^'''"'''' ^^''^"lute 3 Free nir n ,„ inessiac. pirssure. """""•^«"' -^ -" <^-'>l 0.250 73.25I; ;So50 C'olu.n,. ,• shows that a hubble emerges with at. t.Uin.tely Muall e ange oi .aduus. 1,. f.,, the ehauge t. „n the shle of deerea.> be us oi the surlaee hhu bei.g doubled. Now, sn-ee there is pruet.ea y r" me tl at lov surr .uiuhng at.uospherie pre.ssure" has nothing to do ah bursting m. CalhnVs bubbles. Of eoui.e it ,s well known that I'ueas ,1 t ts l>urst in air it is evanesc-ent, but it is necessary for the """lilMrg.st to study tiie te.vture of these bags Sinee a bubble does not expand, how are we troing to aeeount for 4-u.eh bubbk.s"? By coaleseenee (unless electrifieation p -s 1 part). Sometimes they cohere but do not coalesce. AVh n . e • coalesce the large one robs the small one because pre.s.sure varie - ver.ely as the radius (.see Equation 1). The little one 'pumps "ts^^s n.to the large one. We shall have to learn how to control codeseeiL. along ^^ h. ^a,,able .surta-e tension and coalescence. It is not surface tension that breaks bubbles, but it is blows upon a surface that a'k v.sc.osity or toughiu.s and variable surface tension, that eau.se rupture They nipture easily on account of lack of friction of the moleciiles' \V. h low friction a blow is likely to cause the molecules ,0 be sepa: ra cd a distance at which surface tension phenomena disappear before • '- ...olecules have time to come from below and reinforce the area with their greater surface tension. cosi'tv'.'nlT'''' 'f.'"''''^T" '^' ^^PO'-t^^^^ Of ^eat superficial vis- ;^o,sit> ad small ,„,ernal viscosity for the persistenee of a fn.th It ;s said that alcohol which has a superficial vi.scositv le..s than' the i-lemal viscosity, when mixed with supcrfieially viscous liciuids will neu ra e the relative surface viscosity and make frothing ilpo.sible Hen .. the practice of a.lding a few drops of alcohol to check frotbin.^ u, Pharmaceut.cnl work. We know that tannin sometimes interfere; ^^. h flota ion work and also that it may form a colloidal solution with water. Afnv \va ,.^f „.!,] ii._i _i,-i , _, . . - . '"' '•■"'- "■"^'"!'i a.iia taiiiiiu an- deterrents he- cause adsorption is cliecked on account of ■:ntemal viscosity produced ".^ them . For. without adsorption, one of the leading factors tending SMKLTING KLOTATIOX CONCENTKATE 351 to prodiuf u stable froth is miUitk'd, tlial is, varialile surfacf tension. Jly best thanks are due to Dr. W. B. Anderson, profe.ssor of physics in the College, for his helpful sugprcstions and criiiral readiiisr of these notes. SMELTING FLOTATION CONCENTRATE (From tlie Miiiimj ami Svi<:ntifu I'irss of l-Vljniary IJ, I'Jii;) In the November issue of Tcnicntc Topics, the monthly publication of the Hraden Copper Co., Chile, a meniher of the staff briefly outlines the developm. iit of the smelter from 190!) to the present time, iletallurgical difficulties have l)een 'iiaiiy, l)ut were overcome, in spite of being GOOO miles from the base of supplies. The plant now treats 350 tons of concentrate daily, yielding 60 tons of copper, during which operation 60 tons of coke and 10 tons of fuel-oil are burned, employing 350 men and 1500 hp. This (piantity of concentrate is recovered from 4000 tons of ore crushed per day. The concentrate consists of 19^,' copper, 17^0 silica, 23% iron, 2% lime, 8% alumina, and 28% sulphur. It is sandy and .slimy, and contiiins 20% water. Of the 350 tons of concentrate, about 215 tons is dumped from V-shaped steel cars into bins, which supply the nodulizing kilns. This concentrate is then fed to conveyor-belts, thence into kibis, heated by oil-buniers to a temperature of 1750°P. In the kilns, the sandy concentrate is (piickly heated by the burning of the oil. and also by the combustion of a part of the sulphur content, to a sticky consi.itcnce, in which state the rolling motion tends to ))all it into nodules of \ar>ing size. The kilns are sloped an inch per foot toward the discharge-end, out of which the red-hot nodules pour onto an endless chain of cast-iron pans, which convey the product to hoppers ready to charge into the blast-furnaces. The nodules have about the s.ime chemical content as the original concentrate, except that the proportion of sulphur has (wen reduced from 28 to 18%, and, of coui'se. the moisture has l)een evaporated. A by-product of the nodulizers is flue-dust, that is, .a small proportion of the concentrate blown out by the draft in the kilns and caught in dust-chambers, removed, and hauled +0 the bins for re-treatment. Another 50 tons of the original concentrate is .sent to bins th.at discharge to the sinter-plant, of four units. Each unit is a concrete box. 4 ft. wide by 50 ft, long. In place of a top there is a oast-iron grate similar to that of a stationary boiler, but with smaller air- ;j52 TIIK KI.OTATKIN I'KOCKSS iH.l.H. Au ...xl,a,i.sf-ta„ is ,.„„no,.t,.,l fo tho l,ox. .Toatinff a strong d'.WM-dratt ot air tl,r,.n,.h tlu- ^v.u, A 4-in. lay.r of rau- .■..ncentrate IS spr-ad .a flie ^M-af will, an inch lay.T of saw-,]„st ijx,n.,..l with kerosene ..r gasoline torel.es. after the fan has been started The sth began to thin, and, finally, at the end oVfour hours wor? r T i"'" '•"" ■''* ","• "'^" ^•''^'^'•'^ '" "'"*^'' *'^*^ fl°*'>f-» 'nibbles were at ached rising only part way to the surface in a manner similar to that wh.ch I had ob..ved in my initial experiments on loS "t, T"-.^''*'"'''^ ''-^ At the I'lid of four hours crude ore was put into eireulatioii in the mill iiKiiiu; and very sliortly afterwar.l frothing rccommeneed. with the result that the flotation of the mixture of cnide ore and tailing proceeded satisfactorily. Similar residts were obtained during all the sul)8e(iueiit trials. As my records are stowed away in the iiold of this steamer, I am not, at the present moment, able to give accurate figures as to the recoveries obtained. In smelting the flotation concentrate great losses were at first eiicountere.l. A big proportion by weight was lost in the roasters and again when the calcined concentrate was charged into the reverboratory furnaces. Clouds of calcined flotation-concentrate could be seen issuing from. the top of the chimney-stack whenever the feed-hoppers containitig the calcine were opened and the charge dropped into the furnaces. All kinds of devices were tried to over- come ihcsi- losses, but they proved unsuccessful. As a final resort the 'green' concentrate, after having been well drained, was fed through the side doors (the rabbling doors) of the reverberatories and this procedure was ultimately adopted with satisfactory results. As the reverberatories frequently got ahead of the output of the mine and mill, they were, from time to time, used as roasters by being fully charge.! with 'green' flotation -concent rate and run with open doors for several hours until calcination had been completed. I may add that at the works of the Wallaroo & Moonta company it has l)cen found convenient to add to the top of each charge in the blast-furnace a definite quantity of 'green' flotation-concentrate,- which sint.Ts as the charge .sinks and reaches the solidified stage before entering the strong blast area. V. F. Stanley Low. R. M. S. Ionic, October 1. 356 Tin: ri.niAnoN runcKss SIMPLE PROBLEMS IN FLOTATION (Fniiii 111.. Minni,, ,/„./ Snrnlifi,- I'nss of Kebnuiry l:i. i;.!.;) Till' ll'rjhlrr: Sir ()M anntlHT p.^v M,-. D,,,,.]! „i,j,.,,,, ,„ ., „,„„,„„,„ „,. ,_,j,_^, ^__ ■vtr.inl t„ ||„. flontiMtr „f „„ m„i.',v,,m.,| „r..,||.. .„, ual.T. ]U- is ,n..as- "nil.l.v r,t:lit. A., unj:,v.,s..,| ,„t,I|,. will H„al. I.„t not u,,n-h so ..|isilv as tin. uMviis,.,! „„... Tl„. 1,.,|,,.,- u,|| floMt If ph 1 „„ tiM. wat,.r witli- "."''' '"' '•"'•'■• '"" "' ""■ l'">"',.r is l,i,i„|lr,l i„ ,l„. sail,,, wav it u,ll sirii<. My ivtnvn,-,. |„ t|„. ,„;„i,.r was ,|n,.t,.,| fn.i,, tlw 'prior art ' uliirli M, this ivtranl. as in many others. I i"l>''r on ti,.. wat.r in a nip aiwl iahl thr nrnih. upon >t I'v ai.l .,t a pair of piiMvrs. Th,. tissii. -,,ap,.r was ,l,.pr,.sse.l .nt,. th.. wat,.r. h,.,.oi,iinjr w,.ttr,| ^'radually, until it was all soi;»y ami hnally sank, Iraviiitr thr i„...,||,. Hoaliiiir. Without smh ,-arr"? ,.,.iil,| not iiiak,. tho m.i.ill,^ fl,)at. X.'xt I lis,.,! th,. ,.ainphor test I,) as,.,.rtain if th,. wal,.r ha,l lM.,n C().itamiiiat..,l hy trr,.as,.. If ..ainphor is wliittl,.,! with a knitV al.ov,> th.. ual,.r. th,. shavintrs will ,lan,.,. o„ th,' wat,.r in a lif..-nk,. maniur suL'L'.siintr ins,.,.ts in a lit. This phonomonon. as shown hv .Maran-oni '■'' ''"'■ '" ' lis.s..lvinir of th,. ..amphor. prpfVrahly at its point,.,r,.mi' wh..r.. a iiia.Miiiiim siirfar,. is pr,..s,.nt...l to the wat,.r. Th,- solution 'l.rivas.s th.. siirfa,... f.nsion of tho wator in ,.onta,.t. ami th,.r,.l)y oaiisi.s th,. ui!,-ontaminat..,l wat,.r. with its .strong,.r t-.nsion to pull away from th.. sp.,t atr,.,.t,.,l l,y tho oainphor. In or.l.-r to pn.,l,u.e this a..tivity of tho ,'ainplior. tho siirfaoo toiision of th.. Ii,|iii,l must h.. frnat.r than that of tho oainphor s,.lution. Honoo if tr,.,.a.se be intro.lii,.,.,! int,) tho wator. fliorohy hnvrii,..; its surfa... t,.nsion the '■"'"I'li'ir h,.oomos im.rt. If. while th,. ..aiiipn.ir partiol,.s are aotiv.'. th,. \vat..r is t.m..lio,l hy a irroasy linpr,.r (all tiiitr.rs are a little frroa.sy'i the oainphor l...oom..s qniot iiiiiii,.,iiat,.ly. This furnishes a km,1 te.st for the i,r,.som.o of ..yoii a trai.o of s;r.>a.so. Xo ordinarily ',.l,.an' ..ook- illL' llt,.|isil is Slinfl|.i..lltlir t'...!,^ (...„.., , i, .11 " .Miioil mil til th.' ..amplioi. iian(>e. To return t.. the floating unrrreased n.'edle. I introduood so, ne i-i:^- - t SI.Ml'I.K ruolU.KMS I\ FLOTATION' 367 camphor shnvitiRs, and tliry were lively. Then I rcpcatcil tiif .xp.ii- iii.-nt with a iie.'iilc that -as sli(?litly Kipasfd. and the (•aMiph')r seemed to he unaffeeled t.. hy. Finally, I snieand th-' n.'cdi.' with oUve oil: -ui iridescence on the surface of the water indicated ditTiision of the oil. This time the cami)hor chips fell dead on the water, and remained wholly inert. Apparently, therefore, the needle will jiold to it.s.-lf a limited airiount of oil or (frea.se. 'vjiich adheres so selectively as not to contaminate the water. Hut a y excess of oil. more than the needle can hold, will he set free to modify the water and lower its surface tension. ^ Of coui-sc, there is a limit to the si/c of needle that can he floated. When the needle is floating it lies in a dimple or depre.s,sion ; if the needle is so heavy as to overcome the surface cohesion, the sides of the depres.sion meet, and the needle is engulfed in the water. Hulil.les of air can he seen attached to the needle when floating. The film of air is not continuou.s. Apparently the flotation is due to the resist- ance of the water surface to rupture, this resi.stanee being caused l)y an elastic force that pennits the water to yield in the form of a dimple. Jloreover, the air l.iihhles add to the huoyancy. Imth hy their less spccitie gravity and hy preventing the curved walls of the dimple from meeting overheail, that is, hy widening the angle of contact. As the proverh sa.vs, "oil and water will not mix:" the adhesion of air to a metallic surface is matched hy the molecular repulsion hetwcen the oil and the water. As Jlr. Durell suggests, the fact that grease is not es.sential to the floating of the needle is .symptomatic of the trend of the flotation process. The oil is important chiefly as a means of lessening the surface tension of the water and so yi-lding air huhhies that will la.st long enough for the work of buoying the mineral particles. Permit me to continue to di-sagree with Jfr. Durell as to the negligibility of viscosity in the formation of froth. In (pioting Danniell, I was not so out of date, for the reference was to the edition of 1911. We shall hear more about viscosity in the near future. Tn regard to the attachment of previously formed bul>bles to metallic particles: this point has been elucidated by the cinema record of experiments presented in the Miami ca.se. Apparently such bub- bles do attach themselves to the metallic particles, even when un- oiled. lii rcgar.i to the e.\i>.-i irneni dcseriiied and discu.ssed liy .Messrs. Durell and Norris. I have tried it and T r. mmend .'v.'ry student of flotation to trj- it, watch it. and cogitate on it. If kero.senc oil is 358 TIM-; ri.OTATIoN- PKOCKSS p.Miml „vfr colcnMl w cr i.n,l ;,!,• is blown into tlu> lowvr li.|ui.l, a uiuiiImt .sep- ara;ini.' ami surroundinir lliem. When I bl,!w air frently into the cohered water, the rising' liidibles are eolorl-ss. i'':(.y aeeumulate at the .surfa.M. of ibc oil. atid show an attraction for each other, ami for the sides of tim i:la.ss ves.sel. These bubbles aiipear to last loiurer than those blown in the oil. Next, when I in.ject air more rai.idlyluto th.' wat.r. a bubble appears at th.' point of a eon.' .ir nmun.l. as if it w.'re .IrafTKinsr the wat.'r-surfa.'c uith it. This Imbble will remain poise.l for awhile at the peak ..f the niou.ul of wat.'r b.'fore breaking away an.l^ risin- uhile ihe wat.'r falls ba.'k. Tf the air b,' in.j. t.'.i still m.ire rapidly, the bubble breaks through the water-surface, appearinjr to t.'ar it ami tak.'s vvith it a porti.in of wat.'r. /ids is atta.'lied t.^'the south poh' of the bubbl,. an.l may a.'.'.mii.any it t.. th.' surfa.'c, wh.'re, on arrival, it .In.ps away in .'i .'urhMis er.'s.'.'ut f..rm. If I inlro.hi.'e air still nior.' rapidly, thi' water surfa.'c is torn into pi,',.,.s of o.hl shap.' by th" risiiifj bubbles. The bubbles in (,i! are round or ,spherical: those frenerated in the wat.'r. as s....n in their pas,saffe upward thrnuRh the oil, are flatten.'.!; th.'y are oblat.'ly sp|i,.r.,i.lal. The e..lor.'.l-water drop that l.'av s Ih.i s-iuth i)ol.. of the bubbl.', on its arrival at the .surfaee, is also flatt.'ned : SIMPLE PROnLEMS IN' FLOTATION ;{59 if small, it is eresui'iit-shaped ; if larger, it is oblately spiieroidal or lenticular. It will he noted that T Iiave said that this and that "appears" to take plaee. The difTerenee in description by various observers indi- cates how difficult it is to see correctly. These are tndy 'phenomena,' or api)earaiices that are uini.sual and hard to explain." As to .Mr. XorHs's idea that the bubble is simply a hole in the liquid, I would suf^'gest that a globule of air takes to itself a film when 111 an imi)ure liqiiiil. that film containing some impurity or con- taminant in coneeiitratable form. Thus the hole becomes a sac. As the colored water and the kerosene are both impure liquids, we may infer the existence of a film nn the globule of air. as indeed is proved on its arrival at the surface, wli n' bul)bles remain in contact without <'oalescing. The next (|uestion ..risinc: i.s as t.. what <'liange the film of the bubble undergoes in the pa,s,sage of the liublile from one liquid into the other. The watery film would. I sup|M.se. be affected by comiiiu- in r,„ita.'t witli Ih- oil, and it would s.r-m to m,- ,/, /„•;,„•( that the biililile would arrive with a film of the liquid having the lower surface tension. This is a point T would like to ref.r to our friends. Mes.srs, Kal.stoii. Dinvll, .Xorris. and Coghill. all of wii.un have con- tributed .so generously and so usefully on the theory of thi' subject. Tliiit theory is no mm' ai'ademic exercise; it is at the very base of any reasoned understanding of the flotation ])roce.ss. San FraiKMsco. Felimarv 11. T. A. RlCKAKD. T^ INDEX Page ' Absorption 34(5 Adsorption 347 Acid, effect of 131. 157 Flotation method 147 For preferential effect 25!* Sludge fi9 j r^ed at Anacond; 106 Aridity of pulp 229 Adhesiveness of oil and water. 1S2 Agitation, froth method 149 In Faehuca mixer 2:!.") Air, adhesiveness of 14, 15 Adhesion of bubbles to par- ticles 1S7 And bubbles 343 Riil)bles 19S Contact, metallic particles.. 2(il Froth flotation 159 In flotation 26S Introduction of 153 Used in Elmore jirocess 25 ; Alkalinity 93 Effect of 31, S Allen, r.lenn L. Testing ores for flotation 277. 293 I Anaconda Copper M. Co.... 51, lOt! [ Anderson, W. B 351 Arizona CopjiT mill 236 Australian practice 320. 354 1 Treatment of flotation residue 255 1 I Bacon, R. i,S5 | Bains, Thos. M.. ,)r.. Electrical i theory of flotation. .. .225, 25S j Baliantyne, \V. H 2r3 j Blende, preferential flotation.. 259 Block, ,Iames A 244, 324 Why is flotation? 1S7 Bovle's law 349 Braden cojjper mill 351 Pradford method IS ' radford. 1,., process ,S1 ! ub':'e and air , .irticles 343 i!ubble , nrmoi-ing of 133 ! Electrification of 226, -lis I Bursting 13 | Formation of 35s 1 Of carbon dioxide 279 i Surface tension of 313 ; Page Bulk-oil flotation 145 Oil methods 130 Butters, Charles. Cyanide treat- ment of concentrate 203 Flotation of gold ores 276 Treatmeni of concentrate. 59, S9 Caldecott cones 254 Callow, J. M. Notes on flota- tion 231 Callow cell 106, 204 Capacity of 239 Flotation of cBpper ores. . , . 65 .Machine 242, 24:'. Method 67 Patents 4S Plant at Inspiration SS Testing machine 294. 29S Campbell, n. C. 227 Camphor test 356 Canby. R. C 33 Capacity of Callow cell 239 Capillarity 10 Carrionates. effect of 265 Case machine 305 Case School of Aiiplied Science 25n Cattermole, ^. E 40, 71. 193 Method 29, 113, 149 Patent 41 Chalmers & Williams mill.... S4 Chapman. G. A ill Chlorlnation applied to flota- tion concentrate 220 Clennell, .1. E. Cyanide treat- ment of concentrate 203 Coagulation 149, 246 Coal-tar products 239 Coghill. Will H. On froth 344 Surfac:- tension 154 Colloidal impurities, effect of. . 245 Concentrate, cleaning of 2.S6 Concentrate, slllcious 55 Smelting of 351 Treatment o' 59. S9 Conductivity, ele- .rlcal 33S Contact angle 1S2 Copper ores 4S Sulphate 266 Cost of flotation 99, 24,? Of test machine 29S ;ifi2 l.NDKX Coiltts, J ('iiurtiifv, (". K f resylic acid Crushing heforr il„i;ui I'aK.' 113 94 I^'iiie sulphide C.VMnidiriK and flotation, tieat "lent after roasting C.vanidinK taw flotation ron' fi'ntrate S, S4, Iju liHI 207 2:m -M, '>nIy-.JndKe luil] .... "i' Davn.v nietho*. I'eister ( oncentrafor.s nelprat, c. n I'rocess Hensit.v of I, nip ....'.' ,3j^' Of surface film nielectricK Oiffereniial Hisiiosal of 23S 323 S9 147 320 1S3 228 method 140 residue .... ojj^ Horr thickeners r>rainins flotation irit;. 234 concentrate nntoker, A. E. Flofation'^of '"" Kold ores oo ■ Hump ore. flotation of "-< r>"rell. r. Terr.v. Flotation " liriiiciples Wh.v do minerals float? jy IS 319 Klcctrie charges Electrical conductivit lihide.s Theor.v jv;- Klnioie. Francis F. . . Machine Method of siil- 24.1 5S, 333 ... 3(1 ... 294 ,, 34, 1.30 I rocess in Australia .-,4 FIniore vacuum iirocess 34. 44. Kmulsific'ition Fvci'.-^on, Page lOG 319 110 53 279 2S1 237 .'03 14.- f"nrric .1 ,•].-, 14-^ f- A. Flcctro- 321 . 13 190 Fahrenwald. static.q . Film, insulating o-s Filtering concentrate Flotation, a iiarad„x. Flotation: At Anaconda At IJioken Hill At the Central mine At Mt. Morgan ... H.v acid H.v agitation-froth (-'ells in series Classifli'd Concentrate, c.vanidiug Concentrate, raw cyaniding. 2''1 (oncentrate, chlorination of ■>'>o Kffecl of soluhle component Klectrical theory 225 Klectro-statics of History of In Australia. 29, 47, lly, is/. In a .Mexican mill. . In Mexico ' ; Of coi>per ores Of gold ores. A. R. Drucker Of geld ores On dump ore I'neuniatic Preferential Prime requisites Principles Process, the Recovery at .Mt Selective SimiJle i>rol)lenis Smelting of concentrate. Testing ores ... T.»sts "] Theories I'se of lime '■• e.vanidation Flow-sheet of In.spiration mm Fouling of solution Fronient. Alcide Patent Process Froth and flotation...... Agitation Morgan. 2G3 23.S 333 231 319 . 91 . 267 . fi5 ■. 224 . 271; . 354 . 233 . 23,S . 136 319 9 53 332 .•^36 .■;3i 277 92 244 265 99 .';9 263 39 Air-froth . 1 39. 2 4S 267 1, Grienway & Laiiry iiietliod . . . . 79 Grinding for tests 300 Handling of slime i;r)7 HHi-dlnge mill S4, 100 Haynes, William 34 Hebbard, James 20 Flotation at the Central mine 110 Machine 87 Higgins, Arthur H 14!i, !,">;! Hoffman's results ISO Hoover machine. . .49, 287, 2SS, 2S9 Hoover. T. J 47, 158, 322, 3:'.l Horwood i)rocess 7.") Hyde, James M 3'., 4S, 290 Hyde's patent I'lii Hydrates, effect of 265 Hydrogen-sulphide gas 18S Ingalls, W. R 14, 19 Inspiration Consolidated C. Co. 51 ^ii^i 234 Mill, power consumed 241 Mine, flotation at 83 Oil used at 69 Janney, F. G 283 i Flotation machine. .1 tfi, 281, 283 Test-machine 283 Kenyon, \V. H 1 97 Kirby. E. R., patent 4',. n7 Knipp liallniill 121 i Laboratory work 299 I.ead ore. preferential flotation 259 Liebmann. Adolph 33 ' Mme hydrate method 2f;5 In flotation 265 ■ Tse of iDi Litigation 1.-9 Lloyd's Copper Conijiany 354 j Low, V. F. Stanley 355 ■ i'ago Lyster process 77 Machine 2S7 Macqiiislen method 144 Tube 1», 278 .Magistral njill 267 Marcy ball-mill 85 Math"wson, E. P 106 Mexican mill, flotation in 91 Miami experimental plant 161 Method 33 Process at 167, 169 Mickle, Kenneth A 15,141,321 Minerals Separation. . .54, 269, 275 And Fromeat 40 Basic iiatent 30 42 Machine 86 Organisation 29 Patent ...150, 152. 163, 167. 272 Plant 122 Royalties 50 Mitchell, D. P 4s Molecular forces 308 Morning mill 233 Motherwell. Wni. Flotation at the Inspiration mine S3 FICTtion at Mt. Morgan ... 53 MouL.i'n, J. C 114 Mount Morgan, flotation at... 53 Nascent, definition of 325 National copper mill 68, 232 Needle, floating of 326. 357 Norris, Dudley H is", 323 Flotation, a paradox 265 Molecular forcc.^ 30S Patent 45, 269, 274 Niit'er. E. II 48 And Lavers patent 7S Occlusion, definition of 32S Of gas 140, 176 Oil consumption of 70. 240 1 iiilk methods 130, 145 Functlou of 330 Pine f;3, 241 Proportion of 16. 43 Substitutes 153 Oiling of mineral particles. .. . 322 Oils 94, 123 \ . 364 I.N'DEX Oils: Creosote 241 Solubility of [Us Testing of -di I'sed lu flotation i;o. i:,;;. 2:','.< ■• at Mt. Morgan r,,; in Wood niachino 2st) Oliver filters pis Osmosis, description of :];i2 Owen. T. M ^.94 Testing machine ^'Jti Patents 34 Fhysirs of flotiitlon d Pieard, H. F. K 33 Pine oil (13 041 Oil as frother 239 Pneumatic flotation 2:13. 294 Putter api)nratus 3s Charles V 37 147 Method 2?, Power for flotation machines.. 241 Preferential flotation 71 Psychology of flotation 47 i Ralston, O. C, Preferential flotation 71 Testing ores for flotation . i 277, 293 Why do minerals floaf 17.5 Ramage, A, S 73 Reinders' researches 173 Revett, Ben S 9 ! Rickard, T. A 344, 3,i9 The flotation process 9 What Is flotation? 126,144 Roasting flotation concentrate. 213 | Robson, George sp, Rolker, Chas, M.' ft./J 1,51 Royalties .,.*: P.P ! 50 Avoidance o^O^CQiC- 275 Salt, effect of . T.^ V.*'Jt4 »^ ,03 : Salts in solution 154 \ San Pranci.v-n del Oro mill. . . 14,=-. I San Sebasi ;,\n ore oos Sa|)onine, effect on froth 14 | Scott, Walter A. On air-froth. l-,9 ' Separatory funnels for testing, 293 j Shellshear. W. niS|X)sal of residue 248 i 3: Pai • Silica in concentrate ; Silver ores, treatment of | Slide machine ^.i Smelting concentrate Smith, Ralph Soa|i-l)uljbles m i;;2, k Soluble component, effect of. 2i Salts ",| S|iitzkasten, shape of 2s Stability of film 34 Sulltelma plant 2 Sulman, H, L 14 ' Sulman & Pieard iiatent 44. 14'. l.-,3, k; Sulphates, effect of 2t; Sulphoiiation g Surface compression 30; ' Tension, in, 126, 13S, 162. 1S3. 34. " effect of 17; in bubbles 31; i.ieasurement.ll. 127, l,">f and .saltc in solution. ir,l Swinburne, .1 32^ Tension, interfacial 17s Testing machines ,,,.2S.i. 2S7. 2S.S. 291, 293. 295. 296, 29,S Tests, separating funnel 3i,s Thickeners for concentrate.... 2.50 Thicken-^ra for draining con- centrate 253 Tonnage treated by flotation.. 9 Towne, R. S 4,ij Towne-Flinn plant sv Tunbridge patent 191 Vacuum method 27 Viscosity 129, :i29. 350 Wallaroo & Moonfa 355 Washoe Reduction Works 106 Water, electrification 340 Wentworth. H. A 73 Williams. Henry n ]S9 W'ood. H. E 20. 21 Wood machine 280 Method J45 Oils used 69 Zinc separation from galena.. See preferential flotation WL^Ji ■liMM:^ <|4Iv ;■.;>,/ j^r 'X^ fi' '':imi