LIBRARY OF THE UNIVERSITY OF CALIFORNIA. Class QUANTITATIVE METALLURGICAL ANALYSIS QUANTITATIVE METAL- LURGICAL ANALYSI S SELECTED METHODS FOR CHEMICAL ANALYSIS OF ORES, SLAGS, COAL, PIG IRON AND STEEL Arranged by CHARLES FREDERICK SIDENER, B. S. \( Assistant Professor of Chemistry, University of Minnesota The H. W. WILSON COMPANY MINNEAPOLIS 1904 BOOKS OF REFERENCE. C. R. Fresenius Quantitative Analysis. F. Cairns Quantitative Analysis. H. Furman A Manual of Practical Assaying. A. A. Blair The Chemical Analysis of Iron. N. W. Lord Notes on Metallurgical Analysis. M. Troilius Notes on the Chemistry of Iron. J. O. Arnold Steel Works Analysis. F. C. Phillips, Ed. Methods of Iron Analysis in the Laboratories about Pittsburg, Pa. VOLUMETRIC IODIDE METHOD FOR THE DETERMIN- ATION OF COPPER IN COPPER ORES. MODIFIED BY A. H. Low. The method depends upon the following reaction: 2 Cu(C 2 H 3 2 ) 2 + 4 KI = Cu 2 I 2 + 4 KC 2 H 3 2 +I 2 . Cuprous iodide precipitates and a proportionate amount of iodine is set free, which may be determined by titration with sodium thio- sulphate. The reaction is : 2Na 2 S 2 O 3 + 2l=2NaI+Na 2 S 4 O 6 . The standard solution required is that of sodium thiosulphate which may be prepared by dissolving 19.59 grams of the pure salt in a liter of water, and standardizing as follows : Weigh out into two flasks of 200-300 c.c. capacity two por- tions of copper foil of about 0.2 gram each. Dissolve by warming with 5 c.c. of dilute nitric acid (sp. gr. 1.2). Boil for a few moments to partially expel the red fumes and then add 5 c.c. of strong bromine water and boil until the bromine is thoroughly expelled. The bromine is to insure the complete destruction or removal of the red fumes. Remove from the heat and treat the solution by one of the following methods to change the cop- per into the form of copper acetate, (a) Add a slight excess of ammonia water and boil until the excess of ammonia is expelled, as shown by a change of color of the liquid and a partial precipitation of the copper as hydroxide or oxide Now add strong acetic acid in slight excess, perhaps 3 or 4 c.c. of the 80 per cent acid in all, and boil again for a moment if necessary to redissolve the copper, (b) Add 20 c.c. of a cold saturated 144194 2 METALLURGICAL ANALYSIS solution of zinc acetate and heat the solution to boiling, (c) Add sodium carbonate till a permanent precipitate occurs and then acetic acid until the precipitate dissolves, and heat the solution to boiling. Free mineral acids decompose the iodide of potatssium, therefore no free acid stronger than acetic should be present. The condition is attained by any one of the above meth- ods. Cool the solution to the ordinary temperature, and dilute with water to about 50 c.c. Add 3 grams of potassium iodide and shake gently until the salt dissolves. Titrate the solution im- mediately with the thiosulphate until the brown color is nearly destroyed. Add I or 2 c.c. of starch solution, and continue the titration until the blue color disappears. Calculate the strength of the thioslilphate solution in terms of copper. Process Treat one gram of the pulverized ore in a covered casserole, under a hood, with 7 c.c. of concentrated nitric acid and gently heat for a few moments ; add five c.c. of concentrated hydrochloric acid and again heat for a short time. Then add five c.c. of concentrated sulphuric acid and evaporate until dense fumes of sulphuric anhydride are evolved. Cool ; add 50 c.c. of water and heat until the sulphates of copper, iron, etc., have dis- solved. Filter into a small beaker, wash with a little hot water and endeavor to keep the volume of the filtrate down to about 50 or 60 c.c. Place in the beaker two pieces of aluminium about i l /2 inches square, 1 / / 16 inch thick, with the four corners bent for i/ inch al- ternately up and down at right angles. Add five c.c. of concen- trated sulphuric acid, cover the beaker and heat to boiling. Boil for eight or ten minutes. Unless the bulk of the solution is ex- cessive, this will generally be sufficient to precipitate all of the cop- per. Transfer the solution to a flask of 200 to 300 c.c. capacity, rinsing in with hot water, as much of the copper as possible. Al- low the copper in the flask to settle and decant the liquid through a filter, wash the copper two or three times, retaining it as com- pletely as possible in the flask. Pour upon the aluminium in the beaker five c.c. of dilute nitric acid (sp. gr. 1.2) warm gently until the copper is dissolved. Then pour the solution through the filter, receiving the filtrate in the flask containing the main portion of the coppei. At this stage do not wash either the aluminium or METALLURGICAL ANALYSIS 3 the filter, but simply remove the flask and set the beaker in its place. Heat the contents of the flask to dissolve the copper; add 5 c.c. of strong bromine water and boil for a moment to oxidize any arsenic present to arsenic acid. Remove the flask from the lamp and again place it under the funnel. Now wash the beaker, alu- minium and filter with as little hot water as possible. Boil to re- move the excess of bromine but avoid boiling to such a small bulk as to cause decomposition of bromides, etc. Change the copper into the form of copper acetate, add about 3 grams of potassium iodide and titrate with the thiosulphate precisely as described above in the standardization of the thio- sulphate. References on sampling ores : Win. Glenn, Trans. Am. Inst. Min. Engs., Vol. XX, page 155. Rattle and Nye, Jour. An. & App. Chem., Vol. V, page 299. N. W. Lord, Notes on Metallurgical Analysis. A. A. Blair, The Chemical Analysis of Iron. ^References on copper : H. Furman, A Manual of Practical Assaying. A. H. Low, Jour. Am. Chem. 8oc., Vol. XVIII, page 458. A. H. Low, Jour. Am. Chem. Soc., Vol. XXIV, page 1082. VOLUMETRIC DETERMINATION OF COPPER BY POTASSIUM CYANIDE SOLUTION. The method depends upon the fact that the addition of potas- sium cyanide to an ammoniacal copper solution affords a colorless solution. The reaction is : 2 Cu ( NH 3 ) 4 ( N0 3 ) ,H 2 CH-8KCN= ^[Cu (CN) fK 4 +NH 4 CNO-fNH 4 CN+6NH 3 +4KNO 3 . The standard solution required is potassium cyanide, which may be prepared as follows : Dissolve 30 grams of potassium cyan- ide in a half liter of water and thoroughly mix. To standardize, weigh out into two flasks, of 200 to 300 c.c. capacity, two portions of pure copper foil of about 0.3 gram each. Dissolve these in 4 METALLURGICAL ANALYSIS 5 c.c. of concentrated nitric acid; boil off the red fumes, dilute slightly, add 10 c.c. of ammonium hydroxide (sp. gr. .9), cool,, dilute with water to about 100 c.c. and titrate with the potassium- cyanide solution until within a few cubic centimeters of the end, when the bulk of the solution should be noted and distilled water added, if necessary, so that the final bulk will be about 180 c.c. Continue the titration slowly, the flask being shaken after each addition, until the blue or lilac tint can scarcely be discerned at the upper edge of the liquid, when viewed against a white back- ground. Some chemists titrate to a faint rose or pink tint. Cal- culate the strength of the cyanide solution in terms of copper, casserole with 7 c.c. of concentrated nitric acid and gently heat Process Treat one gram of the pulverized ore in a covered for a few moments ; add five c.c. of concentrated hydrochloric acid and again heat for a short while. Then add 5 c.c. of con- centrated sulphuric acid and evaporate under a hood until dense fumes of sulphuric anhydride are evolved. Cool ; add 50 c.c. of water and heat until the sulphates of copper, iron and so forth have dissolved Transfer the contents of the casserole ta a flask of 200 to 300 c.c. capacity, and add 6 grams of sheet zinc, and allow to stand until the copper is completely precipitated. If the action is too slow the flask may be gently heated. Next add 50 c.c. of water and 20 c.c. of concentrated sulphuric acid to rap- idly dissolve the excess of zinc. When the solution of the zinc is complete dilute with water up to the neck of the flask ; allow to settle, and decant the clear supernatant liquid; fill up with water and decant twice more. To the residue in the flask, add 5 c.c. of concentrated nitric acid, and boil to expel red fumes. Dilute with a little water, add 10 c.c. of ammonium hydrate (sp. gr. .9), cool, dilute with water to about 100 c.c. and filter if necessary. Wash: the residue with a little water and titrate the copper solution with a standard cyanide solution. When near the end dilute to 180 c.c.. and finish the titration as described above. Reference : Geo. Ellis, Jour. Soc. Chem. Industry, Vol. VIII, page- 686. METALLURGICAL ANALYSIS 5 ELECTROLYTIC DETERMINATION OF COPPER IN COPPER ORES. Treat one gram of the pulverized ore in a covered casserole, under a hood, with 7 c.c. of concentrated nitric acid and heat for a few moments, add 5 c.c. of concentrated hydrochloric acid and again heat for a short time. Then add 5 c.c. of concentrated sul- phuric acid and evaporate until dense white fumes of sulphuric anhydride are evolved. Cool, add 50 c.c. of distilled water and heat until sulphates of copper, iron, etc., have dissolved. Filter into a weighed platinum dish and wash the residue with a little hot water. Connect the dish with the negative pole of a Bunsen battery of two cells or its equivalent. The current used should be of such a strength that it will decompose water at the rate of 3 to 4 c.c. of oxyhydrogen gas per minute. Place in the. solution a plati- num plate or spiral, connected with the postive pole of the battery. The copper is deposited upon the dish and generally requires from five to ten hours for complete deposition. When the precipitation of the copper appears to be complete, take about 2 or 3 c.c. of the solution out by means of a pipette and test it with a slight excess of ammonia. If copper is found, return the portion tested to the dish, and continue the electrolysis. If no blue color is pro- duced with ammonia the copper is all deposited. Quickly remove the platinum spiral or plate and empty the dish, and wash it two or three times very carefully with distilled water, and then two or three times with alcohol, to wash out all of- the water. Dry the dish and contents for a few seconds in the drying oven at about 105 C. Cool in a desiccator and weigh. A platinum cone may be used for the negative electrode in- stead of the platinum dish. Have the copper solution in a beaker of about 75 c.c. capacity. Place in the solution the platinum cone and platinum spiral, connect the cone with the negative pole of the battery and the platinum spiral with the positive pole and con- tinue the electrolysis as above. COLOR METHOD FOR COPPER. This method is often used for the estimation of copper in 6 METALLURGICAL ANALYSIS substances containing less than 2 per cent, of copper, e.g. in slags from copper smelting operations, and in tailings from concentrat- ing works. The method consists in converting the copper in a sub- stance to be tested, into ammonia-copper-nitrate and comparing th blue color produced, with that produced by dissolving the same amount of a standard copper ore, in the same amount of acid and using the same amount of ammonia as is used in the sample to be tested. Process Weigh out the same amount of sample and standard, and treat with acids as described in the cyanide process, and then precipitate it with zinc. The copper is washed by decantation. dissolved in about 2 c.c. of nitric acid and an excess of ammonia (about 4 c.c. sp. gr. .9) added. Dilute with water, and filter if necessary, into the comparison tubes. Reference : T. Carnelly, Chcm. Neics, Vol. XXXII, page 303. TECHNICAL DETERMINATION OF ZINC IN ORES POTASSIUM FERROCYANIDE METHOD. MODIFIED BY A. H. Low. Preparation of Standard Ferrocyanide Solution Dissolve 22 grams of potassium ferrocyanide crystals in water and 'dilute to one liter. Weigh carefully about o.i gram of pure zinc and dis- solve in six c.c. of. strong hydrochloric acid, using a 400 c.c. beaker. Then add about 10 grams of ammonium chloride and 200 c.c. of boiling water. Titrate with the ferrocyanide solution. The reaction is: ,..ZriCl 2 +K 4 FeCn t= Zn 2 FeCn 6 +4KCl. Continue the titration until a drop, when tested on a porcelain plate with a drop of strong solution of uranium nitrate, shows a brown tinge. The reaction is : K 4 FeCn 6 +2Uo 2 ( No 3 ) 2 = (Uo 2 ) 2 FeCn 6 + 4 KNO 3 . When the titration is about finished, the reaction is much sharper if several drops are placed in the depression of the plate and tested with a drop of uranium nitrate. As this is near the METALLURGICAL ANALYSIS 7 end of the titration the amount of zinc lost by it is insignificant. As soon as a brown tinge is obtained, note the reading of the burette and then wait a minute or two and observe if one or more of the preceding tests do not also develop a tinge. The end point is usually passed by a test or two and the burette readings must be accordingly corrected. A further correction must be made for the amount of ferrocyanide required to produce a tinge under the same conditions when no zinc is present. This is only one or two drops. One c.c. of the standard solution will equal about .005 gram of of zinc or about one per cent, when 0.5 gram is taken for analysis. Assay of Ores To 0.5 gram of the pulverized ore in a 250 c.c. pear-shaped flask, add about 2 grams of potassium nitrate and 5 c.c. of strong nitric acid. Heat until the acid is about half gone and then add 10 c.c. of a cold saturated solution of potassium chlorate in strong nitric acid and boil to complete dryness. Avoid overheating and baking. It is usually necessary to manipulate the flask in a holder over a naked flame to avoid loss by bumping. The boiling may be conducted rapidly, and toward the end it is best to heat the entire flask so as to expel every trace of liquid. The potassium nitrate serves simply as a diluent of the dry residue and insures the completeness of the subsequent extraction of the zinc. Cool sufficiently and add 30 c.c. of a prepared ammoniacal solution and heat to boiling. This solution is made by dissolving 200 grams of ammonium chloride in a mixture of 500 c.c. of strong ammonia water arid 350 c.c. of water. Boil the contents of the flask gently for about two minutes and then filter through a 9 c.m. filter and wash with a hot solution of ammonium chloride containing about 100 grams of the salt and 50 c.c. of strong ammonia water to the liter. Collect the fil- trate in a 400 c.c. beaker. Place a bit of litmus paper in the fil- trate (not necessary if .much copper is present) and neutralize carefully with hydrochloric acid, finally adding 6 c.c. of the strong acid in excess. Dilute to about 150 c.c. and add 50 c.c. of a cold saturated solution of hydrogen sulphide. Heat nearly to boiling and titrate with standard potassium ferrocyanide solution. Make corrections of burette readings as in standardization. Notes. If the ore contains considerable arsenic give it a 8 METALLURGICAL ANALYSTS preliminary treatment as follows : To 0.5 gram of ore in the flask add 10 c. c. of strong hydrochloric acid and one c. c. of bromine. Warm gently for several minutes to decompose the ore without loss of bromine, and then boil rapidly to complete dryness. The arsenic will then be sufficiently expelled. Now add the potassium nitrate' and nitric acid and proceed as above. If the ore contains much copper and cadmium it may be necessary to pass a cur- rent of hydrogen sulphide gas into the hot solution to precipitate them instead of using the water solution of the hydrogen sul- phide. If the precipitate is very large it had better be filtered off and the filtrate titrated as usual. Ores containing copper but no cadmium the copper can be best precipitated with test lead without the use of hydrogen sul- phide as follows : After neutralizing the ammoniacal filtrate from the insoluble residue acidify with an excess of 10 c.c. of concentrated hydrochloric acid and add about 30 grams of test lead. Heat nearly to boiling and stir the lead about until the copper is all precipitated. Now dilute to 200 c.c. and titrate as described without removing the lead and precipitated copper. References : Jour. An. & App. Chem., Vol. XI, page 491. A. H. Low, Jour. Am. Chem. Soc., Vol. XXII, page 198. DETERMINATION OF LEAD IN LEAD ORES. VOLUMETRIC METHOD ALEXANDER'S. This method is based on the fact that ammonium molybdate when added to a hot solution of lead acetate will give a pre- cipitate of molybdate of lead PbMoO 4 , which is insoluble in acetic acid. An excess of ammonium molybdate will give a yel- low color with a freshly prepared solution of tannin. Solution Required A standard solution of ammonium molyb- date containing about nine grams of salt per liter. If the solution is not clear, add a few drops of ammonia. Indicator A freshly prepared solution of one part of tannin to 300 parts of water. Standardising Weigh out .3 gram of pure dry sulphate of METALLURGICAL ANALYSIS 9 lead, dissolve it in hot ammonium acetate, acidify with acetic acid and dilute with water to 250 c.c. ; heat to boiling and run in from a burette the ammonium molybdate solution till the lead is all precipitated. as white PbMoO 4 . This is ascertained by plac- ing drops of indicator on the porcelain plate and to them add a drop of the solution tested after each addition of molybdate. When the end is reached the excess of ammonium molybdate gives a yellow color with tannin. The excess necessary to affect the indicator (about 7 c.c.) must be determined and subtracted from the burette readings. In titrating it is essential to stir the solution very thoroughly, and when near the end to wait a few seconds before trying the drop test. ASSAY OF LEAD ORE. Dissolve one gram of the finely pulverized ore in 15 c.c. of concentrated nitric acid in a covered casserole by the aid of heat. Partly cool and add 10 c.c. of sulphuric acid of sp. gr. 1.41, and evaporate till fumes of sulphuric anhydride appear. Allow to cool and add 100 c. c. of water and heat to boiling for a few minutes. Allow to cool and then decant through a small filter, leaving as much of the lead sulphate, silica, etc., as possible in the casserole. Wash thoroughly with dilute sul- phuric acid, then once with water. Dissolve the lead sulphate from the residue, in the casserole, in a strong hot solution of ammonium acetate, slightly acid with acetic acid. Pour this so- lution through the filter into a clean beaker and repeat -this until all the lead sulphate is dissolved, then wash the contents of the casserole onto the filter with hot water. Acidify the filtrate with acetic acid, dilute to 250 c.c. with hot water and heat to boiling. The solution is now ready for titration, which is done as in standardizing. Consult : H. Furman, A Manual of Practical Assaying. DETERMINATION OF ARSENIC IN ORES AND METALLURGICAL PRODUCTS. CANBY'S MODIFICATION OF PEARCE'S METHOD. Mix 0.5 gram of the pulverized ore with about eight times its 10 METALLURGICAL ANALYSIS weight of a mixture of equal parts of sodium carborate and po- tassium nitrate, in a large porcelain crucible. Heat gradually up to fusion, and keep so for five minutes or more. Cool, treat with boiling water, filter off the insoluble residue and wasfi it with hot water. Acidify the filtrate with dilute nitric acid and boil off the carbonic and nitrous acid gases. Add an emulsion of zinc oxide until it can be seen in some excess in the bottom of the beaker after stirring vigorously and then allowing a few moments to settle. Should an unusually heavy precipitate of gelatinous silica and alumina be produced, filter, wash and add more emulsion to the filtrate. Now add a slight excess of silver nitrate, stirring vigorously to precipitate the silver as silver arsenate, Ag g AsO 4 . Filter and wash with cold water. Now place the beaker in which the precipitation was made, under the funnel, and dissolve off the precipitate with dilute nitric acid, and wash with cold water. Cool the solution, and titrate the silver with standard solution of potassium or ammonium sulpho- cyanate, using i c.c. of a saturated solution of ferric sulphate as indicator. With potassium sulphocyanate, the following are the reactions : AgNO 3 -fKSCN=AgSCN-hKNO 3 and 6KSCN+ Fe 2 (.SO 4 ) 3 =2Fe ( SCN ) 3+3K.SO4. Add the sulphocyanate solution from a burette until a faint amber yellow color can be seen in the solution after vigorous stirring. PREPARATION AND STANDARDIZATION OF THE SULPHOCYANATE SOLUTION. Dissolve 5 or 6 grams of the potassium or ammonium sulpho- cyanate in a liter of water and mix thoroughly. The solution is standardized by dissolving 0.3 or 0.4 gram of pure silver in nitric acid, boiling to expel red fumes, diluting to about 100 c.c. and titrating with the sulphocyanate solution, using i c.c. of the ferric sulphate (or ferric alum) as indicator. Calculate the strength of the solution in terms of arsenic. ^ Note Bennett's Modification of the Pearce Method Decom- pose the ore by fusion, treat with water and filter off the in- soluble residue. Acidify the filtrate strongly with acetic acid; cover and boil rapidly for a few minutes to expel carbonic acid. METALLURGICAL ANALYSIS U Cool and add a few drops of phenolphthalein, then sodium hydrate to just alkaline reaction, then one or two drops of acetic acid, which will discharge the purple red color if too much hydroxide has not been used. The volume of the solution should now be about 100 c.c. Add in slight excess while violently agitating with a stirring rod, a neutral solution of silver nitrate and allow to* settle for a few minutes. Filter, wash the precip- itate with cold water, dissolve it in dilute nitric acid and cool. Dilute to about 100 c.c. and titrate the silver with a standard sul- phocyanate solution, using i c.c. of ferric sulphate as indicator. Calculate percent. As. References : A. H. Low, Chem. New's, Vol. XLVIII, page 85. L. M. McCay, Chem. News, Vol. XLVIII, page 7. Canby, Trans. Am. Inst. Min. Engs., Vol. XVII, page 77. R. Pearce, Proc. of the Colo. 8ci. Soc., Vol. I. J. F. Bennett, Jour. Am. Chem. 8oc., Vol. XXI, page 431. DETERMINATION OF CHROMIUM IN CHROME IRON ORES. METHOD OF A. G. MCKENNA. Weigh 0.5 gram of the finely ground ore in a nickel or iron crucible. Mix with the ore three or four grams of sodium per- oxide. Hold the crucible over a Bunsen burner by means of a pair of tongs and heat until fusion begins. Keep the mass in a liquid condition at a low red heat for about five minutes. Cool, then place crucible and contents in a number four beaker and add hot water to cover the crucible. Cover the beaker with a glass cover and keep warm until the fusion dissolves. The chromate passes into solution, and the ferric hydroxide remains undissolved. Remove the crucible ; and heat the solution to boiling for fifteeen minutes. Allow the liquid to cool for a moment, then acidify with dilute sulphuric acid adding 10 c.c. in excess of the amount necessary to dissolve the ferric hydroxide. The sulphuric acid, converts the sodium chromate to sodium bichromate. The reaction is : 2Na 2 CrO 4 +H 2 SO 4 =Na 2 Cr 2 O 7 +Na 2 SO 4 +H 2 O. 12 METALLURGICAL ANALYSIS Dilute the solution with cold water to about 300 c.c. and add 70 c.c. of ferrous sulphate solution prepared as follows: Dis- solve 25 grams of ferrous sulphate crystals in water to which has been added 10 c.c. of dilute sulphuric acid. Dilute the solution to 500 c.c. and mix thoroughly. The reaction between the so- dium bichromate solution and ferrous sulphate in presence of sulphuric acid is as follows : 3 Fe 2 (S0 4 ) 3 +Cr 2 (S0 4 ) 3 +Na 2 S0 4 +7H 2 0. Now determine the excess of ferrous sulphate which has been added by means of a standard solution of potassium permanganate (or potassium bichromate). Determine the exact strength of the ferrous sulphate solution as follows : Run out from a burette into a beaker about 30 c.c. of the ferrous solution ; add about 10 c.c. of dilute sulphuric acid ; dilute to about 150 c.c. and run in the permanganate from the other burette until the pink color becomes permanent. Calcu- late the amount of iron oxidized by the chromium from the chrome ore and then the weight of chromium in solution and the percentage in the ore. References : E. H. Saniter, Jour. Soc. Chem. Ind., 1896, page 155. Genth, Chem. Neios. Vol. VI, page 31. Kennicutt & Patterson, Jour. An. d App. Chem., Vol. Ill, page 132. J. Massignon, Jour. An. & App. Chem., Vol. V, page 465. A. G. MoKenna, Proc. Enfj. Soc. Western Pa., 1896 & 1897. F. C. Phillips, Ed., Methods of Analysis in the Laboratories Around Pittsburg, Pa. PARTIAL ANALYSIS OF SLAG. Silica Weigh out .5 to I gram of the pulverized slag into a casserole. Decompose with hydrochloric acid and a little nitric acid and evaporate to complete dryness. Heat the residue for about one hour in a drying oven at 130 C. to dehydrate the silica. Add 5 c.c. of hydrochloric acid, heat, add water, heat again and filter, wash with hot water, ignite, and weight SiO . If BaSO 4 is present treat with hydrofluoric acid and get the silica by loss in weight. Barium Treat another portion of from .5 to i gram with hydrochloric and a little sulphuric acid. Evaporate to dryness, METALLURGICAL ANALYSIS 13 heat until fumes of sulphuric anhydride appear. Add water, and hydrochloric acid, heat, filter, wash with hot water ignite and weigh SiO.,+BaSO 4 . Subtract from this the SiO 2 as determined above to get BaSO 4 . Lime Method I Heat the filtrate from the silica to boiling, add ammonia in slight excess, and then a strong solution of oxalic acid in excess to dissolve the iron and aluminum precipitate. Heat the solution to boiling to precipitate calcium oxalate. Allow to stand for a short time to settle, then filter and wash thoroughly with hot water. Place the funnel over a clean beaker, and by means of a glass rod make a hole in the filter, and wash the pre- cipitate through the funnel into the beaker. Wash the filter paper with a little hot dilute sulphuric acid. If the sulphuric acid fails to dissolve the last traces of the calcium oxalate a little hydro- chloric acid may be used, and the filter paper again washed with hot water. The reaction is CaC 2 O 4 +H 2 SO 4 =CaSO 4 +H 2 C 2 O 4 . Dilute the solution to about 100 c.c. Add about 15 c.c. of sulphuric acid, heat to about 70 C. and titrate the oxalic acid with standard per- manganate solution. Calculate the per cent, of CaO. Note Tartaric acid may be used instead of oxalic acid to dis- solve the hydroxides of iron and aluminum, and the calcium then precipitated with ammonium oxalate. This method is not satis- factory d the slag contains more than 0.5 per cent, of manganese. Method II Treat one gram of the pulverized slag with water and hydrochloric acid. Boil gently until the slag is decomposed. Dilute the liquid, nearly neutralize the acid with ammonia. Make a basic acetate precipitation, filter and determine the calcium in the filtrate as folows : concentrate the solution and precipitate the calcium with ammonium oxalate. Determine the lime volumet- rically as in method I. Note If much manganese is present the calcium oxalate must be redissolved and reprecipitated before making the titration. Or the manganese may be precipitated with bromine and filtered off before adding the ammonium oxalate. Magnesia may be determined in the filtrate from the cal- cium oxalate by precipitation with hydrogen sodium phosphate in presence of an excess of ammonia. Iron, Lead, Copper, Manganese, Zinc Follow the methods 14 METALLURGICAL ANALYSIS described in the notes on the analyses of various ores, taking sep- arate portions for each. ANALYSIS OF BLAST FURNACE SLAG. Fuse 3 grams of the finely pulverized slag with 15 grams of anhydrous sodium carbonate and 0.5 gram of sodium nitrate in a platinum crucible. Allow to cool, decompose the fused mass with hot water. Acidify with hydrochloric acid and evaporate to dry- ness in a porcelain dish or casserole and heat the residue for about one hour at no-i3OC. to dehydrate the silicic acid. Moisten the residue with concentrated hydrochloric acid, warm gently, add water, heat and filter into a quarter liter graduated flask. Wash the silica well with, hot water, ignite and weigh the Si0 2 . Dilute the solution in the flask to the containing mark and mix thoroughly. Note Some varieties of slag are soluble in hydrochloric acid and therefore do not require fusion with sodium carbonate and sodium nitrate, in which case treat the slag with hydrochloric acid and a little nitric acid, evaporate to dryness, dehydrate the silicic acid and continue as above. Determination of the Iron Take out 50 c.c. of the solution. Reduce the iron with stannous chloride and continue as directed on page 2.1. Calculate the per cent, of Fe 2 O 3 . Determination of the Phosphorus To 100 c.c. of the solution add ammonia until the mass sets to a stiff jelly, making sure that there is present an excess of ammonia. Next add strong nitric acid in sufficient amount to bring the solution to a clear amber color, and continue as directed on page 24. Determination of Alumina, Manganese, Lime and Magnesia Take 50 c.c. of the solution in a large beaker, add sodium car- bonate until the fluid is nearly neutral and then to the clear red liquid add a solution of about five grams of sodium or am- monium acetate, dilute to about 500 c.c. with boiling distilled water. Heat to boiling for a minute or two, filter while hot and wash by decantation with hot water. Dissolve the precipitate in METALLURGICAL ANALYSIS 15 hot dilute hydrochloric acid, add a little water, heat to boiling, add ammonia in slight excess, filter, and wash with hot water. Ignite and weigh Fe. ( O. { , Al O., and P O r . Calculate the per cent, of Fe O,, Al O. and P (X. The per cent, of ALO is determined by "2 o 2 3L, 2 Jo subtracting the per cent. Fe O and P O r previously determined J, o Jo from the above. Add the filtrate and washings from the acetate precipitation to those from the precipitation by ammonia, evaporate the solution to about 200 c.c. When cold add bromine water until the solution is strongly colored, add ammonia in slight excess and heat mod- erately for some time, then filter off precipitate of MnO (OH) 2 , wash with hot water. Test filtrate with more bromine and am- monia, dry, ignite and weigh Mn 3 O 4 . Calculate the per cent. MnO. ; Instead of igniting the precipitate of hydrated peroxide of r.ianganese it may be dissolved in an excess of standard ferrous sulphate solution, containing a little sulphuric acid, and the ex- cess of the ferrous salt determined with a standard solution of permanganate or bichromate of potash. See Ford-Williams pro- cess, page 30. Note The amount of calcium carried down with the man- ganese depends largely upon the relative quantities of calcium and manganese. W T hen the amounts of each are over 0.02 gran? a double precipitation of the manganese should be made. When a slag contains a very large amount of manganese inste?d of precipitating with bromine, add ammonia to the solution in slight excess and enough ammonium sulphide to precipitate ill of the manganese, allow the precipitate to settle. Filter the manganese sulphide by decantation and wash three times with a 5 per cent, ammonium nitrate solution containing i or 2 c.c. of ammonium sulphide, finally transfer the precipitate onto the filter paper, dry, ignite the filter paper in a weighed porcelain crucible, add the precipitate, heat at first over a small flame with the crucible cover off, finally increase the heat and at last heat over the blast lamp to constant weight. Weigh Mn 3 O 4 . Calcu- late per cent. MnO. Instead of weighing the manganese as Mn.,O 4 the sulphide may be filtered off and determined as describ- ed on page 28. Acidify the filtrate, from the manganese precipitate, with hy- 16 METALLURGICAL ANALYSIS drochloric acid and concentrate to about 100 c.c., filter if nec- essary. Add ammonia in slight excess, then precipitate the cal- cium with ammonium oxalate as calcium oxalate, CaC O 4 . Filter, wash, ignite and weigh CaO. Calculate the per cent, of CaO. The precipitate of calcium oxalate may be dissolved in dilute sulphuric acid and the CaO determined volumetrically by means of a stan- dard permanganate solution. See page 13. To the filtrate from the calcium oxalate add a volume of am- monia of sp. gr. .q6, equal to one-third the volume of the solu- tion. Then add hydrogen sodium phosphate drop by drop while stirring the solution with a glass rod, to precipitate the magne- sium as ammonium magnesium phosphate. Allow to stand for some time, filter, wash with a mixture of one part of ammonia, sp. gr. .96, and thiee parts water, dry, ignite and weigh Mg P O.. Calculate the per cent, of MgO. Determination of the Sulphur To the remaining 50 c.c. of the original solution add a few drops of hydrochloric acid, heat to boiling in a beaker and precipitate the sulphur with barium chlo- ride as barium sulphate, BaSO 4 . Calculate the per cent, of sulphur. The above applies to the analysis of open hearth slags, refinery slags, tap cinder, mill cinder and converter slag. Basic slag, from the Thomas Bessemer Piocess, which often contains a high per cent, of phosphoric acid, requires that the process be slightly modified. METHOD FOR THE COMPLETE ANALYSIS OF LEAD AND COPPER SLAGS, MATTES AND CINDERS. Treat 1.5 grams of the pulverized material with about 20 c.c. of hydrochloric acid, (sp. gr. 1.2), a few drops of concentrated nitric acid and about 2 c.c. of concentrated sulphuric acid in a casserole. Evaporate until heavy white fumes of sulphuric an- hydride are evolved. Cool and add about 25 c.c. of water. Heat for some time and again cool. Filter off the SiO , BaSO 4 and PbSO 4 . Wash with dilute sulphuric acid (i vol. of concentrated acid to 20 vol. of water) by decantation, leaving as much as pos- METALLURGICAL ANALYSIS 17 sible of the residue in the casserole. Set the filtrate aside for the determination of Fe, Al, Cu, Zn, Mn, Ca and Mg. Digest the residue in the casserole with a strong solution of ammonium acetate, to dissolve the lead sulphate, and filter on the filter used in the first operation. Wash with hot water con- taining a little ammonium acetate. Ignite the residue of SiO 2 and BaSO 4 , cool and weigh in a platinum crucible. Separate and determine the SiO 2 and BaSO 4 by either of the following methods : (a) To the residue in the crucible add 4 or 5 drops of dilute sulphuric acid, and add i or 2, c.c. of hydrofluoric acid and evap- orate under the hood to expel the silica as SiF 4 . Ignite and weigh the residue of BaSO 4 and calculate BaO. The weight of barium sulphate subtracted from the weight of barium sulphate plus silica gives weight of silica. (b) Fuse the insoluble residue of silica and barium sulphate with 3 or 4 grams of sodium carbonate. Dissolve the fused mass in hot water and boil. Filter and wash with hot water until the washings are free from sulphates. Acidify the filtrate with hy- drochloric acid and evaporate to dryness and determine the SiO 2 in the usual manner. Dissolve the precipitate on the filter paper in dilute hydrochloric acid, wash the filtter with hot water, heat the solution to boiling and precipitate the barium by adding dilute sulphuric acid. Allow to stand for some time, filter, wash and ignite. Weigh BaSO 4 . Determine the lead by either of the following methods : (a) To the filtrate containing the lead acetate add acetic acid to acid reaction, dilute with water to 250 c.c., heat to boiling and titrate with standard ammonium molybdate solution, using tannin (i to 300) for indicator. See page, 8. (b) To the filtrate containing the lead acetate add sulphuric acid, allow to stand for a short time and filter off the lead sulphate. Wash at first with dilute sulphuric acid (i vol. of con. H 2 SO 4 to 20 vol. water) and then with alcohol to displace the sulphuric acid. Dry, ignite and weigh the PbSO 4 in a porcelain crucible. Calculate the per cent, of lead. To the filtrate containing the Cu, Fe, Al, etc., add a little L/drochloric acid, heat to about 70 and precipitate the copper as copper sulphide with H 2 S. Filter, wash with hydrogen sul- 18 METALLURGICAL ANALYSIS phide water, dry, transfer the precipitate to a weighed Rose crucible, burn the filter, add the ash to the contents of the cru- cible. %Add a little sulphur, ignite in a current of hydrogen or coal gas. Allow the crucible and contents to cool in a current of the gas, and weigh as Cu S. Calculate per cent, of copper. Instead of weighing as Cu 2 S, the precipitate may be placed in a beaker, the filter ash added, and the precipitate dissolved in nitric acid, when the copper may be determined electrically, colorimetrically or by the volumetric method. Boil the filtrate from the CuS to expel all the hydrogen sul- phide, filter if necessary, add a little concentrated nitric acid and boil for a short time, to oxidize the iron. Cool, add sodium car- bonate until the solution is nearly neutral. Add about 5 grams of sodium or ammonium acetate and then about a half liter of hot water, heat to boiling and boil for two or three minutes. Al- low to settle for a few moments. Filter while hot and wash with hot water by decantation. Dissolve the precipitate in hot dilute hydrochloric acid, add a little water, heat to boiling, add ammonia in slight excess, filter and wash with hot water. Dissolve this pre- cipitate of iron, alumina (and P 2 O 5 ) in hydrochloric acid and dilute with water to 250 c.c. Take 100 c.c. of the 250 for volumetric determination of iron. Take another 100 c.c. and pre- cipitate the iron, aluminum and phosphorus with ammonia. Filter, wash and ignite and weigh Fe 2 O 3 , A1 2 O 3 , P 2 O 5 . Combine the filtrate from the basic acetate precipitation with the filtrate from the first ammonia precipitation, acidify with acetic acid and boil. Conduct into the boiling solution a current of hy- drogen sulphide for half an hour. Filter off the precipitate of ZnS and wash with water, containing hydrogen sulphide. If the precipitate of zinc sulphide is not very large it may be dried and ignited in a porcelain crucible, with the addition of a little ammonium carbonate to assist in the conversion of the zinc sulphide into zinc oxide, cooled and weighed as ZnO. If the precipitate of zinc sulphide is quite large dissolve it in hot dilute hydrochloric acid and precipitate the zinc as basic carbonate of zinc with sodium carbonate added in excess and the solution boiled. Filter, wash, dry, ignite in a porcelain cru- cible and weigh as zinc oxide. Calculate the per cent, of zinc. Boil the filtrate from the precipitate of zinc sulphide with an METALLURGICAL ANALYSIS 19 excess of bromine water for about half an hour. Add ammonia to alkaline reaction and a little more bromine water and heat the solution just below boiling until the precipitate is brown col- ored and flaky, and the solution colorless. Filter off the pre- cipitated hydrated peroxide of manganese, MnO (OH) , wash thoroughly with hot water, test filtrate for manganese with more, bromine and ammonia, heat for some time and filter if necessary, dry, ignite and weigh Mn^O . Calculate the per cent, of manganese. Instead of igniting the manganese precipitate, it may be transferred to a beaker and determined by the Williams method. See page 30. See also methods for the determination of manganese in blast furnace slag, page 15. In the filtrate from the manganese determine the calcium and magnesium in the usual manner. Determination of Sulphur Take a separate portion using the method described on page 31. COAL AND COKE ANALYSIS. Pulverize 10 to 15 grams of the carefully sampled coal and transfer it to a tightly corked bottle. Moisture Dry one gram of the pulverized coal in an open porcelain or platinum crucible at 104- 107 for one hour. Cool in a desiccator and weigh Covered. Volatile Combustible Matter Place one gram of the fresh, undried, powdered coal in a platinum crucible weighing twenty or thirty grams and having a tightly fitting cover. Heat over the full flame of the Bunsen burner for seven minutes. Cool and weigh. To find volatile combustible matter, subtract the per cent, of moisture from the loss found here. Ash Burn the portion of the powdered coal used for the de- termination of moisture, at first over a very low flame, with the crucible open and inclined till free from carbon. Cool and weigh. Examine the ash for unburned carbon by moistening it with alcohol. Fixed Carbon This is found by subtracting the per cent, of ash from the per cent, of coke as found above. 20 METALLURGICAL ANALYSIS Sulphur Eschka's Method Mix thoroughly one gram of the finely powdered coal with one gram of magnesium oxide, and one half gram of dry sodium carbonate, in a thin platinum dish having a capacity of 75 c.c.-ioo c.c. The dish is heated on a triangle over an alcohol lamp, held in the hand at first. Gas must not be used on account of the sulphur it contains. The mixture is fre- quently stirred with a platinum wire and the heat raised very slowly, especially with soft coals. The flame is kept in motion and barely touching the dish, at first, till strong glowing has ceased, and is then increased gradually till in 15 minutes the bottom of the dish is at a low red heat. When the carbon is burned transfer the mass to a beaker and rinse the dish, using about 50 c.c. of water. Add 15 c.c. of saturated bromine water and boil for 5 minutes. Allow to settle, decant through a filter. Boil a second and third time with 30 c.c. of water and wash till the filtrate gives only a slight opalescence with silver nitrate and nitric acid. The volume of the filtrate should be about 200 c.c. Add one and a half cubic centimeters of concentrated hydro- chloric acid. Boil till the bromine is expelled and add to the hot solution, drop by drop, especially at first, and with constant stir- ring 50 c.c. of a 2 per cent, solution of hot barium chloride, Digest oh a water bath until the precipitate settles. Filter, wash, ignite, cool and weigh BaSO 4 and calculate the per cent, of sulphur. Note For practical purposes the sulphur may be considered as existing in the coal in the form of pyrites, and that in the above analysis one-half of the sulphur passes off with the volatile combustible matter and the other half with the fixed carbon. In calculating results of analysis, one-half of the sulphur may be subtracted from the volatile matter and the other one-half from the fixed carbon. If a determination of phosphorus is de- sired, it may be found in the ash after burning the coal or coke and can be determined by any of the well known methods and the per cent, deducted from the per cent, of ash. If the calculations are made as indicated above, the sum total of moisture, volatile matter, fixed carbon, ash, sulphur and phos- phorus should equal one hundred per cent. Reference : Jour. Am. Chem. Soc., Vol. XXI, page 1116. METALLURGICAL ANALYSIS 21 DETERMINATION OF IRON IN IRON ORES. Standardisation of Potassium Permanganate Solution: Dissolve about eight grams of potassium permanganate crys- tals in about 500 c.c. of water, with frequent agitation to in- sure complete solution, if possible. After this, allow the solu- tion to stand for two or three days. Filter through a layer of asbestos, dilute to about 2000 c.c. and mix thoroughly. Weigh out and place in number 2 beakers two portions of stan- dard iron ore of about 0.5 gram each. Pour over each of these 10 c.c. of hydrchloric acid (sp. gr. 1.2), and as much stannous chloride solution as will nearly reduce the iron, cover the beakers with glass covers, heat at a temperature just below boiling until the undissolved residue is white or nearly so. The stannous chloride solution should be of -such strength that about 3.5 c. c. will reduce one-half gram of the average iron ore. It may be prepared by dissolving pure tin in hot con- centrated hydrochloric acid leaving an excess of the acid and then properly diluting with distilled water, or By dissolving 100 grams of stannous chloride salt in 70 c.c. of concentrated hydrochloric acid and diluting with distilled water to one half liter. If a dark residue remains, collect it on a filter, wash free from hydrochloric acid, and ignite the filter in a platinum crucible. Mix the ash with a small amount of sodium carbonate and heat to fusion. Cool and dissolve the fused mass in boiling water in the crucible. Unite solution and precipitate (if any) with the acid extraction. Heat the solution then to boiling, wash off the cover and sides of the beaker and add stannous chloride solution to the hot solution until it is colorless, but avoid adding more than a drop or two in excess. In case a larger amount has been added, add permanganate solution until a tinge of ferric iron is produced. Destroy this as above. Dilute with 100 c.c. of water and cool completely; when cold add rapidly about 30 c.c. of mercuric chloride solution (50 grama per liter). Allow the solution to stand 3 minutes, dilute with water to about 300 c.c. Next add about 10 c.c. of a solution prepared as follows : 160 grams of manganous sulphate dissolved in 1750 c.c. of water, to which is added 330 c.c. of phosphoric acid syrup (sp. gr. 1.7) and 320 c.c. of concentrated sulphuric acid. 22 METALLURGICAL ANALYSIS Titrate the solution as quickly as possible with the potassium permanganate to the appearance of a faint pink color, which re- mains permanent for a short time. The reaction for the oxida- tion of the iron from ferrous sulphate to ferric sulphate by the permanganate in presence of sulphuric acid is as follows : ioFeSO 4 +2KMnO 4 -j-8H 2 SO 4 5Fe 2 (SO 4 ). { +K 2 SO 4 -f2MnSO 4 -i-8H O. Calculate the strength of the permanganate in terms of metallic iron. Standardisation of Potassium Bichromate Solution : Dissolve about 12 grams of potassium bichromate in approxi- mately 2000 c.c. of water. Mix thoroughly and standardize by means of standard iron ore. Decompose and reduce the ore just the same as in the standardization of permanganate solution. Omit the addition of the manganous sulphate mixture. Titrate the re- duced iron solution with the potassium bichromate solution. The reaction is : 6FeCl 2 +K 2 Cr 2 O_+i4HCl=6FeCl 3 +2C+Cl 3 +2KCl+7H o O. The end point in the titration is reached when a drop or two of the iron solution and a drop of very weak solution of freshly pre- pared potassium ferricyanide gives no blue color when brought to- gether on a porcelain tile. Reaction : 3FeCl 2 -f2K 3 Fe(CN) (5 ^Fe 3 Fe 2 (CN) 12 +6KCl. Calculate the strength of the potassium bichromate solution in terms of metallic iron. It is advantageous, when one has a great many determinations of iron to make to dilute the standard solution so that each c.c. is equivalent to one per cent, or two per cent, of metallic iron, when 0.5 gram is taken for analysis. E.g., suppose it is desired to have a permanganate solution of such a strength that each c.c. will represent I per cent, of metallfc iron when 0.5 gram is taken. The calculation is as follows : ioFeSO 4 +2KMnO 4 +8H SO 4 = ~5Fe ( SO 4 ) r +K SO 4 +2MnSO 4 -f 8H.,O. loFe : 2KMnO 4 .005 : x or 560 : 316 .005 : x x = .002811 grams KMnO 4 per c.c. .002821 x 100 = 2.821 grams of KMnO 4 per liter. METALLURGICAL ANALYSIS 23 StilJ another practice in commercial work is to weigh out the ore in such proportions, that the burette readings of the standard solution give the percentage at once without calculation. Thus, if the standard ore contains 64.43 per cent, iron, the weight of ore would be so taken that the readings of the burette would be 32:215 c.c. If, however, it should be so taken that the reading is 32.8 c.c., then the weight would be diminished in the proportion ot 32.215 to 32.8. For the obtaining of the percentage the burette reading is doubled. The Process; Pulverize the ore in an agate mortar to a fine powder. If nec- essary dry the ore in a drying oven until its weight is constant. Weigh out duplicate samples of 0.5 gram each. Place each sample in a number 2 beaker and add 10 c.c. of hydrochloric acid (sp. gr. 1.2) and heat on the iron plate. If the ore contains organic matter add a little potassium chlorate and boil till the smell of liberated chlorine has disappeared. Add stannous chloride and continue as in the standardization of the permanganate solution with standard iron ore. Or, if it is desired to use the bichromate method, continue as in the standardization of potassium bichromate with standard iron ore. Two results on the same sample should agree within o.i per cent. References : K. W. Mahon, Am. Chem. Jour., Vol. XV. page 360. Jour. Am. Chem. Koc., Vol. XVII, page 405. Jour. An. & App. Chem.., Vol. V, page 325. DETERMINATION OF PHOSPHORUS IN IRON ORES. EMMERTON'S VOLUMETRIC METHOD Dissolve 3 grams of the pul- verized ore in 40 c.c. of concentrated hydrochloric acid, and evap- orate to about 20 c.c.. avoiding a temperature so high as to con- vert the ferric chloride into ferric oxide. Add 10 c.c. of concen- trated nitric acid and evaporate down to about 10 c.c. If the nitric acid solution is allowed to go to dryness, it affords ferric oxide, insoluble in nitric acid, which always retains some phosphate. This can only be brought into solution by hydrochloric acid, which must be removed by addition of more nitric acid and evaporating. Dilute with about 20 c.c. of distilled water and filter into an Erlen- meyer flask of about 400 c.c. capacity and wash with the least pos- 24 METALLURGICAL ANALYSIS sible amount of water. It is not always possible to get the whole of the phosphorus in solution by the above process, therefore the residue should be treated by one of the following methods in order to obtain any insoluble phosphorus which may be present. (a) Ignite the residue in a platinum crucible, fuse it with 5 to 6 parts of sodium carbonate, dissolve the fused mass in water and hydrochloric acid, evaporate to dryness in order to dehydrate any silicic acid that may be present. Moisten the residue with concentrated nitric acid, heat after adding a small amount of water, and filter into the flask containing the soluble phosphorus, (or into another flask if it is to be determined separately). (b) Ignite the residue in a platinum crucible, add 3 or 4 drops of dilute sulphuric acid and about 5 c.c. of hydrofluoric acid, and evaporate under the hood to complete dryness and finally ignite to redness. Fuse the residue with 5 to 6 parts of sodium carbonate, dissolve the fused mass in water and nitric acid and add it to the solution in the flask containing the soluble phosphorus. (c) Place residue and filter paper in a platinum crucible and ignite. When the paper is burned off break up the residue with a platinum rod and ignite at a red heat for about two minutes. Pul- verize the ignited residue in an agate mortar. Transfer the resi- due to beaker, add water and a little nitric acid and boil gently for about 5 minutes. Filter into the flask containing the soluble phosphorus. To the solution add ammonia, shaking the flask after each addition, until the mass sets to a stiff jelly. Then add strong nitric acid gradually, shaking well after each addition, until the precipi- tate dissolves and then add a little in excess to get a clear amber color. The solution at this point should be about 200 to 250 c.c. in bulk. Put a thermometer into, the liquid and heat carefully un- til the temperature reaches 8sC. Add at once 50 c.c. of ammonium molybdate solution to precipitate the phosphorus as phosphomo- lybdate of ammonium, (NH 4 ) 3 PO 4 , i2MoO 3 , I2H 2 O. Close the flask with a rubber stopper, wrap it in a thick cloth or towel and shake or whirl for five minutes, then allow to stand for five min- utes for the precipitate to settle. Filter and wash the precipitate five times with water containing 10 c.c. concentrated nitric acid per liter and then five times with water, containing ten grams of potassium nitrate per liter. Put the funnel containing the yellow METALLURGICAL ANALYSIS 2 5 precipitate in the neck of a flask of about 400 c.c. capacity in which has been placed 15 grams of granulated zinc. Pour over the precipitate on the filter dilute ammonia (one vol. ammonia, sp. gr. .96, and three volumes of water) and receive the solution in the flask containing the granulated zinc. Next pour into the flask 100 c.c. of dilute sulphuric acid (i vol. acid to 5 vol. of water) and heat on the iron plate for about 15 minutes. The rolor of the solution passes through pink, plum, pale olive green to dark green. The MoO g is reduced by the zinc and sulphuric acid to a mixture of oxides corresponding to the formula Mo 24 O S7 , Filter through a folded filter. The zinc is decanted on to the filter paper with the liquid to keep up the reducing action. Wash two or three times with water. Titrate with standard potassium perman- ganate solution, to the appearance of the pink color due to the slight excess of permanganate. The reaction is : The strength of the permanganate solution in terms of MoO 3 is '88. 1 6 per cent, of its strength against iron. The yellow precipi- tate of phosphomolybdate of ammonium contains i2MoO 3 to i of P, the phosphorus being 1.794 Per cent, of the MoO g . Therefore 88.16% of the strength of the solution in terms of iron gives its strength in terms of MoOs and 1.794% of this gives its strength in terms of phosphorus. Let Fe=the iron value of the permanganate. Let P' phosphorus value. ThenP=Fe X .015816. Two results on the same sample should agree within .001%. It is advisable to check the strength of the standard perman- ganate in terms of phosphorus as calculated above by means of a standard iron ore of known phosphorus content, or by means of some of the pure yellow precipitate dried at uoC. It contains 1.63 per cent, phosphorus. Emmerton, Trans. Am. Inst. Min. Engs., Vol. XV, page 93. Dudley & Pease, Jour. Am. Chem. Soc., Vol. XVI, page 224. Blair & Whitfield, Jour. Am. Chem. Soc., Vol. XVII, page 747. G. Auchy, Jour. Am. Chem. Soc., Vol. XVIII, page 955. W. A. Noyes, Jour. Am. Chem. Soc., Vol.. XVI, page 553. W. A. Noyes, Jour. Am. Chem. Soc., Vol. XVII, page 129. Mixter & Du Bois, Jour. Am. Chem. Soc., Vol. XIX, page 614. H. C. Babbitt, Jour. Am. Chem. Soc.. Vol. VII, page 165. E. D. Campbell, Jour. Am. Chem. Soc., Vol. VII, page 2. Dudley & Pease, Jour. Am. Chem. Soc., Vol. VII, page 519. P. W. Shimer, Jour. Am. Chem. Soc., Vol. XXI, page 723. 26 METALLURGICAL ANALYSIS Reduction of the MoO^in a Reductor: Obtain the yellow precipitate and dissolve it in ammonia just as described on page 25 and the solution is allowed to run into a clean beaker. Wash the filter paper with water until the solution measures about 60-70 c.c. Add to the liquid in the beaker 10 c.c. concentrated sulphuric acid and pass it through the reductor which has just been cleaned by passing through it distilled water and then loo c.c. of warm dilute sulphuric acid, strength : 25 c.c. con- centrated sulphuric acid per liter of distilled water. After passing the molybdate solution through the reductor, wash with about 200 c.c. of the warm dilute sulphuric acid, and finally with about 50 c.c. hot water. References : Jones' Reductor, Trans. Am. Inst. Min. Engs., Vol. XVII, page 441 Dudley & Pease, Jour. An. & App. CJiem., Vol. VII, page 109. Acidimetric Method Follow Emmerton's method until the yel- low precipitate of ammonio-phospho-molybdate is obtained and then continue as follows : Filter the yellow precipitate on a 9 c.m. filter and wash by decantation with water containing 10 c.c. con- centrated nitric acid per liter and then five times with water con- taining 10 grams potassium nitrate per liter. Place precipitate and filter in the flask containing the bulk of the precipitate. Dis- solve the precipitate in an excess of standard solution of caustic soda or caustic potash. With potash the reaction is : 2 (NH 4 ) 3 P0 4 +24MoO a +46KOH+H 2 0= (NH 4 ) 4 H 2 P 2 8 H-(NH 4 ) 2 Mo0 4 +2 3 K 2 Mo0 4 +2 3 H 2 0. Add water and a few drops (.5 c.c.) of phenol phthalein indicator and titrate the excess of caustic alkali with a standard solution of nitric acid. Solutions Required: Standard Caustic Potash Strength, 8.3334 grams of potassium hydroxide per liter. This solution may be prepared from nor- mal caustic potash solution by taking 148.39 c.c. and diluting to one liter with distilled water. One cubic centimeter of this solu- tion will equal .0002 gram of phosphorus. Standard Caustic Soda Strength, 5.9355 grams of sodium hy- droxide per liter. This solution can be prepared from normal METALLURGICAL ANALYSIS 27 caustic soda by diluting 148.39 c.c. to one liter. This solution is of such a strength that one c.c. equals .0002 gram phosphorus. Standard Nitric Acid This solution has the same strength, volume for volume, as the caustic soda or caustic potash. It can be prepared by diluting 148.39 c.c. of normal nitric acid to one liter. It contains 9.3484 grams of nitric acid to the liter. Phenol Phthalein One gram dissolved in 100 c.c. of 60% alcohol. Calculation of Analysis The difference between the number of c.c. of caustic alkali used and the number of c.c. of standard acid multiplied by .0002 gives the weight of phosphorus found. Weight of Phosphorus X 100 - = per cent, phosphorus. Amount of ore taken . It is advisable to check the strength of the standard acid and alkali in terms of phosphorus as calculated above, against a stan- dard iron ore of known phosphorus content, or by means of some of the pure yellow precipitate dried at noC. It contains 1.63 per cent, phosphorus. References : J. O. Handy, Jour. An. d App. Chem., Vol. VI, page 204. Manby, Jour. An. d App. Chem., Vol. VI, page 82. M. Rothberg, Jour. An. & App. Chem., Vol. VI, page 241. F. Hundeshagen, Zeit. Anal. Chem., Vol. XXV, page 489. Wood's Method Direct weighing of the phosphomolybdate of ammonium. Follow Emmerton's method until the yellow precipitate is ob- tained then filter on a 9 c.m. filter which has been previously dried at uoC. and weighed. Wash with a two per cent, nitric acid solution until free from iron, then wash once or twice with alco- hol. Dry in the air bath at 110 C. and weigh. 1.63 per cent of the dried precipitate is phosphorus. Note The yellow precipitate must contain no silica. With ores containing soluble silicates, evaporate the acid solution to com- plete dryness, to render the silica insoluble, moisten with hydro- chloric acid, add water, heat, and filter off the insoluble residue.. Reference : E. F. Wood, Zeit. Anal. Chem., Vol. XXVIII, pages 141- 172. 28 METALLURGICAL ANALYSIS DETERMINATION OF MANGANESE IN IRON ORES. VOLHARD'S METHOD, MODIFIED BY G. C. STONE Grind the ore to a fine powder. Weigh out two portions of about one gram each and place in number 2 beakers. Pour into each 10 c.c. of concen- trated hydrochloric acid. Cover the beakers with glass covers and heat until ore is decomposed. Add a little potassium chlorate and boil a minute or two. Remove covers and evaporate off ex- cess of acid. Cool and add cold water. At this point if there is any doubt as to the decomposition of the ore, filter off and test insoluble residue for manganese. If not, the filtration may be omitted. Wash contents of the beaker into a half liter flask with cold water. Nearly neutralize with carbonate of soda; the solu- tion should remain clear and should be of a deep red color. Next add an emulsion of zinc oxide until the precipitate curdles and set- tles readily. Add a little more of the emulsion to make sure that the precipitation is complete. The reaction is : Dilute to the mark with cold water, mix thoroughly, pour into a beaker and allow the precipitate to settle. Take portions of 200 cc. each of the supernatant liquid and transfer to 400-500 c.c. flasks ; heat nearly to boiling and titrate one after the other with standard potassium ^permanganate solution, adding it in small portions at a time, and shaking the flask over a.Bunsen flame, after each addition. Keep the temperature as near the boiling point as possible, while making the titration. The greater part of the per- manganate solution should be added at once and the solution vig- orously shaken and then the precipitate allowed to settle. The fol- lowing is the reaction which takes place : 4KMnO 4 +6MnCl -f4H 9 O=ioMnO 2 -f4KCl+8HCl. In the above equation we see that two molecules of potassium per- manganate oxidizes three molecules of manganous chloride, while in the following equation : 2KMnO 4 -f-ioFeSO 4 -f-8H 2 SO 4 = 5 Fe 2 ( S0 4 ) 3 +K 2 S0 4 -f2MnS0 4 +8H 2 we see that two molecules of potassium permanganate oxydizes ten molecules of ferrous sulphate, therefore the oxydizing power of KMnO 4 in the former case is only 3 / 10 as great as in the latter. METALLURGICAL ANALYSIS 29 So the value of the permanganate in terms of manganese is to its value in terms of iron. as 3 : 10 or 55 / 56 X V 10 = 165 /56