s 14. GS: CIR 9.<\(* c. *> GxlA SaftOu^ STATE OF ILLINOIS WILLIAM G. STRATTON, Governor DEPARTMENT OF REGISTRATION AND EDUCATION VERA M. BINKS, Director ILLINOIS FLUORSPAR G. C. Finger H. E. Risser J. C. Bradbury DIVISION OF THE ILLINOIS STATE GEOLOGICAL SURVEY JOHN C.FRYE, Chief URBANA CIRCULAR 296 1960 ILLINOIS GEOLOGICAL SUrtvt_Y LIBRARY JUL 12 1960 ILLINOIS STATE GEOLOGICAL SURVEY 3 3051 00004 248 ILLINOIS FLUORSPAR CONTENTS Page Page PART I - GEOLOGY, MINING, AND MILLING PART III - USES OF FLUORSPAR AND FLUORINE CHEMICALS Direct uses of fluorspar 21 Hydrofluoric acid manufacture 21 Metallurgy 22 Ceramics 24 Water fluoridation 25 Miscellaneous 26 Uses of fluorine chemicals 27 Hydrofluoric acid 27 Aluminum fluoride and synthetic cryolite 27 Fluorocarbons 28 Petroleum alkylation 31 Atomic energy 31 Elemental fluorine 31 Other inorganic fluorides 32 Fluosilicic acid and salts 33 Directory of Illinois fluorspar mines and mills 33 References 34 Geology 5 Mineralogy 5 Producing districts 5 Vein deposits 5 Bedded deposits 7 Mixed deposits 8 Relation of deposits to kind of rock 8 Minerals comprising ore deposits 8 Mining 9 Vein mining 10 Mining of bedded ore 10 Milling 11 Hand-picking and washing 11 Jigging 11 Heavy media separation 1 1 Flotation 12 Commercial grades 12 Exploration for additional deposits 12 PART II - ECONOMIC ASPECTS Trends in fluorspar consumption 14 Production trends 17 Marketing 19 Summary 20 ILLUSTRATIONS Figure 1 - Principal districts of the fluorspar mining region 2 - Schematic cross- sections of fluorspar deposits 3 - Stratigraphic column of southeastern Illinois 4 - Mining in a vein deposit 5 - United States consumption of fluorspar, 1941-1959 6 - Location of steel and hydrofluoric-acid plants, 1957 Plate 1 - Specimens of fluorspar TABLES 1 - Fluorspar consumed in the United States, by uses, 1957-1958 2 - Fluorspar shipments from Illinois mines, 1930-1958 3 - Fluorspar consumed in the United States, by states, 1957-1951 4 - Consumption of HF in 1957 6 7 9 10 15 19 16 17 18 28 ILLINOIS FLUORSPAR G. C. Finger, H. E. Risser, and J. C. Bradbury ABSTRACT This circular describes in nontechnical form the geology, pro- duction, economic aspects, and uses of Illinois fluorspar. The fluorspar deposits, found principally in Hardin and Pope Counties of southeastern Illinois, occur as fissure fillings in faults and as replacement bodies in limestone. Production comes from under- ground mines. Modern mills up-grade the raw fluorspar ore to provide a finished product for use in the metallurgical, ceramic, and chemical industries. Lead and zinc are important by-products. Illinois for many years has been the leading producer of fluor- spar in the United States, a position due in part to strategic geograph- ical location with respect to water, rail, and highway transportation, and to consuming industries. More than 50 percent of the fluorspar produced is used in the chemical industry for the manufacture of hydrofluoric acid, a basic material in production of fluorine chemicals. The metallurgical indus- try, especially in the open-hearth steel process, consumes about 40 percent of the fluorspar as a fluxing agent. Most of the remaining fluorspar is used as a flux and opacifying agent in the ceramic indus- try for the manufacture of glass and for enamel coatings on sinks, bathroom fixtures, stoves, refrigerators, signs, and the like . Fluorine chemicals are useful in aluminum production, atomic energy processing, rocket and missile fuels, water fluoridation, re- frigerants, aerosol propellants, plastics, insecticides, fungicides, medicinal s, and in many other specialty products. INTRODUCTION From the hills of southern Illinois comes a mineral which performs many important and essential functions in modern industry — the mineral fluorspar. In the making of steel, enamels, aluminum, special glasses, and a host of chemicals, Illinois fluorspar plays an important part. For many years the state has been the country's largest producer of this mineral, and modern mines and mills afford a continuing supply and variety of grades of spar to meet the most demanding require- ments of industry. The part of the report on "Geology, Mining, and Milling" was written by J. C. Bradbury, geologist; "Economic Aspects" by H. E. Risser, mineral economist; and "Uses of Fluorspar and Fluorine Chemicals" by G. C. Finger, chemist. Acknowledgments The cooperation of the Illinois fluorspar producers during the preparation of this report is gratefully acknowledged. Special thanks for assistance on uses are due R. M. Grogan, geologist, E. I. du Pont de Nemours and Company, Wilmington, Delaware; R. B. McDougal, commodity specialist, United States Bureau of Mines, Washington, D. C; A. H. Stuewe, chemist and market analyst, Nopco Chemical Company, Newark, New Jersey; and William Coolbaugh, metallurgist, Matthiessen and Hegeler Zinc Company, LaSalle, Illinois. [3] Illinois State Geological Survey Circular 296, Plate 1 PART I GEOLOGY, MINING, AND MILLING The following paragraphs contain a brief, non-technical account of the ge- ology, mining, and milling of Illinois fluorspar. For a more comprehensive and technical treatment, the reader is referred to Weller, Grogan, and Tippie (34). (Numbered references are listed at the end of this report.) GEOLOGY Mineralogy Fluorspar, also called fluorite, consists of two chemical elements, cal- cium (51 percent) and fluorine (49 percent), and is known chemically as calcium fluoride (CaF2). It is a glassy mineral with a hardness of 4 and a specific gravity of 3.18. Illinois fluorspar is commonly colorless, white, or grayish, but some of it is purple, pink, blue, green, yellow, or tan. Characteristically, crystals of fluorspar have a cubic shape (pi. 1A), and pockets of such crystals are found in the southern Illinois deposits. However, most of the fluorspar is massive, that is, in a compact body of interlocking crystals. Producing Districts The fluorspar of Illinois occurs in Hardin and Pope Counties in the extreme southern part of the state. Rosiclare, Cave in Rock, and Elizabethtown are head- quarters for the mining industry. Figure 1 shows the distribution of the mining districts. The main production of the area has come from the Rosiclare vein system, a belt of mineralized faults in the vicinity of the town of Rosiclare, and from the bedded replacement deposits of the Cave in Rock district, a northeast-trending belt of "blanket" deposits about three miles north of the town of Cave in Rock. Prominent outlying areas include the Stewart vein system, just south of Eichorn in western Hardin County, and the Empire district, an area of vein deposits in eastern Pope County about two miles northwest of Eichorn. Vein Deposits Vein deposits are steeply inclined, sheet-like deposits that occur as fis- sure fillings along faults, and their width and continuity depend on the degree of openness of the faults in which they were formed. A fault is a crack in the rocks of the earth's surface along which movement has taken place. In the fluorspar area EXPLANATION OF PLATE 1 Specimen of fluorspar from a cavity, showing characteristic cubic crystals. About one-eighth actual size. Polished specimen of banded fluorspar. Light bands are coarse-grained, darker bands are fine-grained fluorspar. About half actual size. ■ Polished specimen of banded fluorspar-zinc ore. Light bands are fluorspar, darker bands are sphalerite (zinc sulfide). About half actual size. [5] ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Herod o o Eddyvi f • i) Hicks oEichorn / «t Elizabethto.wn-"^ SCALE 12 4 Oi Golcondo Fig. 1 - Principal districts of the fluorspar mining region. Main production has come from 1) Rosiclare district and 2) Cave in Rock district. Others are 3) Goose Creek vein, 4) Lee vein, 5) Hamp mines and vicinity, 6) Empire district, 7) Lusk Creek fault zone, 8) Stewart vein system, and 9) Interstate group and vicinity. the faults are usually vertical or nearly so, and the rocks on one side of the faults have dropped down whereas those on the other side remained stationary or moved upward. At some places there was also sideward movement along the faults. The fault surfaces were never perfectly even; instead they were wavy and irregular, preventing a good fit of one side of the fault against the other. As a result, the walls of the fault were pushed apart, producing openings in which fluor- spar veins were later deposited. At the time of faulting, some rock along the fault was crushed and broken. The amount of vertical movement along a fault also had an important bear- ing on the formation of ore deposits. For example, a small amount of vertical movement, 25 feet or so, probably would not push the fault walls far enough apart to create large open spaces in which the ore minerals could be deposited. Con- versely, along the very large faults that had 1000 feet or more of vertical movement, the crushing and grinding were so intense that few open spaces of suitable size were left for formation of minable ore deposits. However, faults of moderate dis- placement commonly had less shattering and therefore possessed more favorable characteristics for ore deposition. Within the fluorspar district, faults of 100 to 200 feet displacement generally offered the best conditions for vein deposition. The exact manner in which the fluorspar veins were formed is not known. Presumably, they were deposited by crystallization from hot, rising solutions that originated deep below the surface of the earth. ILLINOIS FLUORSPAR 7 Bedded Deposits The bedded replacement deposits (fig. 2) generally are flatlying, irregular bodies of ore parallel to the beds of the host limestone. Typically, the deposits are elongate and range from 200 to more than 2500 feet in length and 50 to 300 feet in width. Thicknesses are commonly 4 to 15 feet, with the ore wedging out at the margins. ORE BODY SYMMETRICAL ABOUT CENTRAL FISSURE SCALE Fig. 2 - Schematic cross-sections of two general types of bedding-replacement fluorspar deposits (from Grogan, 1949). Unlike the vein deposits, in which the fluorspar simply filled open fissures, the bedded deposits were formed by a chemical reaction between the fluorine-bear- ing solutions and the limestone in such a way that the calcium carbonate of the limestone was changed to calcium fluoride or fluorite. Probably the reason for this difference in behavior of the solutions was the character of the fracture zones through which they moved. The vein deposits, it will be recalled, are found in faults of considerable displacement, along which open spaces as much as 30 feet wide were formed. The bedded deposits, on the other hand, follow groups of joint-like fractures or minor faults of a few inches to 20 feet displacement where the amount of movement was not enough to create large openings. Along the larger faults, then, ample space was provided for the mineralizing solutions to deposit their load, but the lack of 8 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 open space in the joints and minor faults caused the solutions to move out laterally along bedding planes, or possibly, even through the pores of the less dense layers of rock. The resulting intimate contact between solutions and rock led to chemical reaction between the two and the resulting replacement of limestone by fluorite. Mixed Deposits In addition, a few other deposits, combining features of the bedded and vein deposits, generally occur in faults of small (approximately 25 feet) displace- ment. The deposits are characterized by a rather narrow (2 to 3 feet) vein with local widenings where certain limestone beds are replaced by fluorspar. On some veins, as the Pierce vein in the Empire district, the favorable bed may be replaced for a length of several hundred feet along the vein. Relation of Deposits to Kind of Rock Just as the character of the faults influences the size or type of deposit, the various kinds of rock also have their effect on the deposits, both vein and bed- ded. Figure 3 shows the succession of rock formations present in the fluorspar district. In the veins, the best deposits occur where the fault walls are composed of the stronger, or more competent, rocks (limestones and well-cemented sand- stones) . The weaker, or less competent, formations, such as shale and shaly limestone or sandstone, were easily crushed by movement along the fault and tend to fill rather than create openings. Because they are strong and competent, the Ste . Genevieve and St. Louis Limestones generally are the most favorable strata for vein deposits. Good vein deposits may be found in higher formations, but because many higher rocks are shaly, the deposits are likely to be of limited size. Some competent rock units exist in these higher beds, but the accompanying incompetent beds tend to plug the fault, causing numerous barren or lean portions along the vein. The bedded replacement deposits occur chiefly in a relatively small ver- tical thickness of rock from the base of the Bethel Sandstone downward to the mid- dle part of the Fredonia Limestone (fig. 3). The principal deposits are found at only three favored positions within this 190-foot interval — in the limestone at the top of the Renault Formation, in the top part of the Fredonia Limestone, and near Ihe level of the Spar Mountain Sandstone Lentil, 45 to 60 feet below the top of the Fredonia — possibly because these limestone beds are more pure, more porous, or more fractured than other beds. Minerals Comprising the Ore Deposits The valuable minerals of the fluorspar deposits are fluorite, sphalerite (zinc sulfide, ZnS), and galena (lead sulfide, PbS) . The latter two are the common ore minerals of zinc and lead, respectively. The mineral calcite (calcium carbonate, CaC03) is common in the deposits but is of little commercial value at present. At some places barite (barium sulfate, BaSO^ is abundant. In the veins, fluorite and calcite are the only minerals commonly present. Sphalerite and galena, if present, occur only at scattered places, usually at the margins of the veins, and represent only a minor product of vein mining. Barite has been found at various places but noteworthy concentrations are known in only a few areas. Apparently the last mineral to be deposited during the ore-forming period, it occupies the central parts of fluorspar veins or occurs in narrow fissures next to the veins. ILLINOIS FLUORSPAR SYSTEM PENNSYL- VANIAN 0_ IS) IS) IS) FORMATION Cypress- Paint Creek- Bethel LITHOL- OGY Renault Downeys Bluff Member Shetler- ville Member Levias Member Rosiclare Member Ste Genevieve Fredonio Member St. Louis I I wwwwrr J =r^ CCXXXSmjXS DESCRIPTION Sandstones and shales 700' 800 Alternating limestones, shales, ond sandstones 800-900 Sandstone; shole or shaly sandstone in middle portion 200' -240' Fluorspar bedded deposits Limestone l0'-40' Shale and limestone 30'-50' Limestone 10' -40' Sandstone 15-45 Fluorspar bedded deposits Limestone 100 - 220 Spar Mountain Lentil (sandy bed) Fluorspar bedded deposits Limestone Fig. 3 - Principal fluorspar-bearing portion of stratigraphic column of the southeastern Illinois fluorspar district. Cross-hatched parts represent horizons most favorable for the occurrence of bedded de- posits . The most productive parts of veins generally occur below the shaly Renault Formation. In the bedded deposits, as in the vein deposits, fluorite is the chief valu- able mineral, but sphalerite and galena are important ore minerals in some places. Calcite is less common than in the vein deposits but is abundant locally. Barite is almost entirely absent in some deposits but abundant in parts of other deposits. The fluorite commonly occurs as alternating coarse- and fine-grained layers in banded ore (pi. IB) and as massive bodies of various shapes within the orebodies. Where abundant, sphalerite takes the place of the fine-grained fluorite layers in banded ore (pi. 1C). Galena occurs in the coarse-grained layers of banded ore as separate masses one-fourth to 3 inches in diameter. Barite occurs as alternating layers with fluorite in banded ore and also as massive bodies that have filled cav- ities or replaced limestone or fluorite. MINING Most fluorspar produced in southern Illinois comes from underground mines, although minor tonnages are produced from open pits in shallow, weathered cjeposits 10 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 where the common types of earth-moving machinery, such as bulldozers, power shovels, and drag lines, are used. Underground mining methods must be suited to the particular type of deposit being worked and, generally, are shrinkage stoping in the vein deposits and room-and-pillar methods in the bedded deposits. • Sheave Skip or can rl for hoisting ore Vein Mining In vein mining (fig. 4) a vertical shaft is first excavated in the rock adja- cent to the vein. From this shaft a tunnel-like opening, called a cross-cut, is driven horizontally into the vein at a selected depth below the ground surface. On reaching the vein, a drift (horizontal tun- nel following the vein) is driven and serves as a haulage level and starting point for shrinkage stoping. The stope (open space made as ore is taken from the vein) is excavated upward from the drift by drilling and blasting. In wide veins, the roof of the drift is commonly an arch of vein ma- terial left in place (fig. 4), but in nar- row veins, the roof is made with tim- bers. The broken ore is drawn from the stope into mine cars through bins and hauled to the shaft for hoisting to the surface. Only enough ore is removed during the stoping operation to give working room to the miners (fig. 4). Other haulage levels may be driven above or below the in- itial level, usually at vertical in- tervals of 100 feet, and stoping is continued upward from one lev- el to the next. If the overlying drift is to be preserved, an arch of unbroken vein material is left in place. Mining of Bedded Ore Bedded fluorspar deposits are mined underground by a mod- ified form of the room-and-pillar method in which the ore is exca- vated from rooms, and pillars are left between the rooms to support the mine roof. Bedded deposits that are exposed on steep hill slopes can be mined by driving a tunnel, called an "adit," directly into the orebody. Vertical shafts are sunk to those not easily Vein Fig. 4. - Mining in a vein deposit. Top drawing is a section at right angles to the vein show- ing the general relations of surface installations and underground workings to the vein. Lower drawing is a view parallel to the vein and il- lustrates the shrinkage stoping method of vein mining. The space between the roof of the drift and the undisturbed vein material is called the "stope. " ILLINOIS FLUORSPAR 11 accessible by such direct means. In either case, a main haulage drift is usually driven along the center of the orebody, and rooms are mined out from it at irregular intervals and continued through the workable deposit. The ore is drilled and blasted, loaded by machines into cars or trucks, and hauled to the mine shaft, or, if an adit mine, to bins or stockpiles on the surface. The larger mines are highly mechanized, MILLING The fluorspar ore, as it comes from the mines, commonly comprises a mix- ture of fluorspar, calcite, and various amounts of limestone or other rock that are unavoidably mined with it. In addition some of the ore also contains valuable sphalerite and galena. It is usually necessary to rid the ore of the waste calcite and rock and to separate the fluorspar and other valuable minerals. Hand-picking and Washing A few small mines use hand-picking to separate lumps of fluorspar from the ore in order to get a premium product, but most ore goes through one or more me- chanical processes to beneficiate it. The simplest process, washing, is useful in separating spar from contaminating clay. This usually is satisfactory only for the weathered ores and involves the use of a mechanical washing device, known as a log washer, or washing on a vibrating screen or trommel. Jigging To process their ores, a few small mills use jigging which makes use of the fact that fluorspar is heavier than most waste materials occurring with it. The method employs water as the separating medium. By an up-and-down pulsating action, the lighter material is floated over the sides of the jig cell while the heav- ier fluorspar remains behind. However, as the specific gravity of fluorspar is not greatly different from that of the waste materials (fluorspar 3.1; calcite 2.7; quartz 2.7; limestone 2.6 to 2.7), jigging does not effect a high degree of separa- tion. Jigging has been used chiefly for producing the lower commercial grades of fluorspar and, until a few years ago, in the larger mills as a primary separation process to get rid of a portion of the waste materials before putting the ore through a subsequent milling operation. Jigging has also been used to separate galena (specific gravity 7.5) from mixed fluorspar-galena ores, but, except in special circumstances, this part of the processing is now done by a more effective method. Heavy Media Separation A newer and more efficient separation process based on differences in spe- cific gravities is heavy media separation (HMS) by which the ore minerals are sep- arated from waste in a cone containing a suspension of finely ground ferrosilicon in water. The specific gravity of the suspension, or heavy medium, is maintained between 2.55 and 2.62 at the top and 2.85 and 3 . 1 at the bottom of the cone. Crude ore is introduced at the top of the cone, and particles having specific gravities greater than that of the medium near the bottom, such as fluoride and the sulfides, sink and are recovered at the bottom of the cone. Particles of lesser grav- ity such as quartz and calcite are buoyed up and carried away with the overflow from the cone. Ferrosilicon is washed from the ore and waste materials, recovered magnetically, and returned to the cone. The product of heavy media separation may be marketed directly or further processed by flotation. 12 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Flotation Most of the higher grades of fluorspar shipped from Illinois are concentrates made by a process called flotation. This process makes use of the property of cer- tain reagents or oily liquids to selectively coat specific minerals. In a mixture of the finely ground ore in water, air bubbles will adhere to the mineral grains thus coated and cause them to float. In practice, a chemical frothing agent is added to the ore-water mixture and air is bubbled through it. The bubbles sweep the select- ed particles to the surface of the flotation cell where the froth is collected and de- watered by filtering. Flotation is of much value to the Illinois fluorspar industry because it allows the use of leaner ores and also permits the efficient separation of the valuable lead and zinc minerals, galena and sphalerite, which occur with fluorspar in some de- posits . Commercial Grades and Specifications Fluorspar is marketed in three general grades — metallurgical, ceramic, and acid. Metallurgical grades, used chiefly in steel making, specify a certain number of effective units of CaF2, usually expressed as "effective percent of CaF2." This figure is obtained by subtracting l\ times the percentage of silica (Si02) from the percentage of CaF2 in the fluorspar concentrate. For example, a concentrate as- saying 85 percent CaF2 and 5 percent Si02 will contain 7l\ percent effective CaF2« The grades most commonly listed in market quotations are 60, 70, and ll\ percent effective CaF2« Ceramic and acid grades of fluorspar are of higher purity than metallurgical grades, and specifications are expressed in percentage of CaF2» Ceramic grades generally range from 85 percent to 96 percent CaF2- Acid grade, used chiefly in the aluminum and chemical industries, must contain 97 percent or more CaF2 . Exploration for Additional Deposits The ability of Illinois fluorspar mining industry to continue to supply a vi- tally needed raw material to the nation's industries depends upon a forward-looking exploration program to discover new deposits. In the early days of fluorspar mining in Illinois, the miner had only to sink a shaft or drive an adit into an outcrop of ore. As the mining industry grew and the good surface showings of ore were used up, prospecting solely by underground excavations became too costly, and drills that could penetrate and sample the rock came into general use. Today, systematic drilling programs are guided by geologists who are train- ed to evaluate information gained by the study of surface rock exposures and drill- ing samples. But the future will see the need for even more subtle ore-finding methods. To this end, mining company exploration staffs and Illinois State Geolog- ical Survey geologists are constantly on the alert for new ideas on ore occurrence or new methods of exploration. Geochemical exploration, involving the application of chemical analytical methods to field geology, has been tried with varying degrees of success in recent years by the mining companies and by the Survey. One company is claiming good results in tracing a vein by analysis of soil samples for fluorine. Various geophysical methods also have been investigated by both govern- ment and private interests. The United States Geological Survey, in cooperation with the Illinois State Geological Survey, demonstrated that some faults can be ILLINOIS FLUORSPAR 13 discovered and accurately located by an electrical method called "earth resistivity." The seismic method, consisting of measurement of the velocity of artifical earth- quake waves generated by a small charge of dynamite, has been tried by the Illinois Survey in a limited way and also appears to be capable of detecting and tracing faults . Photogeologic techniques, used in the district for several years, involve the inspection of pairs of aerial photographs with the aid of a stereoscopic viewer. The three-dimensional effect thus produced helps to emphasize minor differences in topography and vegetative cover, aiding in the mapping of rock structures such as faults. This procedure is reported to be a useful tool in the search for new min- eralized belts and is credited by one company with several important discoveries. Standard field geology methods are being employed by the Illinois Survey in the revision of the 1920 geologic map of the mining district. The availability of new and more accurate topographic base maps, in the process of completion by the United States Geological Survey, and the existence of a wealth of data ac- cumulated by the mining companies through exploration drilling over the last 40 years, make it possible to produce more detailed and accurate maps. Begun in the 1958 field season, the new map, through a more accurate location of faults and in other ways, is expected to be an important aid in the discovery of new deposits in the fluorspar district. PART II ECONOMIC ASPECTS The first recorded fluorspar mining in Illinois was in 1842 when a small operation was begun in Hardin County near the site of the present Rosiclare mine (14). Since that year production has been more or less continuous, although ship- ments from the area apparently did not begin until about 1870. From the beginning Illinois was a major source of production in the United States and for many years has been the principal producer. To date, it has provided more than half the total fluor- spar produced within the United States. Illinois' eminent position as a producer of fluorspar stems primarily from the ready accessibility and strategic geographic location of its deposits that, lying at relatively shallow depths, are readily exploited. Surrounding the fluorspar de- posits, and closely linked to them by railway, highway, and waterway networks, are major centers of industrial, chemical, and steel production. Nowhere else within the United States are fluorspar deposits so favorably situated. Prior to 1888, the United States' consumption of fluorspar was very small and, according to existing records, probably never exceeded 5,000 tons per year. The material was used principally in production of glass, enamel, and hydrofluoric acid, although smaller amounts were used in smelting nonferrous and precious met- als. That year the introduction of commercial open-hearth steel production into the United States opened up a new market whose importance quickly overshadowed all former uses . TRENDS IN FLUORSPAR CONSUMPTION Following the introduction of the open-hearth process, United States' consumption of fluorspar rapidly increased, starting at about 5, 000 tons per year in 1888 and reaching a maximum of approximately 645,000 tons in 1953. For more than 60 years the steel industry was the leading consumer of fluorspar, and, until World War II, commonly accounted for 75 to 80 percent of the total quantity consumed. With so large a portion of the total going into steel, the fluorspar industry was vi- tally affected by the frequent ups and downs of steel production. Despite the marked increase in the use of fluorspar in steel production over the years, the use for this purpose has failed to keep pace with growth in steel output, especially in the last 30 years. The failure of fluorspar consumption to parallel steel production resulted from improved methods and efficiency which re- duced fluorspar usage from 7.4 pounds per ton of open-hearth steel in 1927 to less than 4 pounds per ton in 1957. From 1927 to 1957, steel production rose from 45,000,000 tons to about 113,000,000 tons per year, for an increase of 151 percent. During the same period, fluorspar consumed in steel manufacturing increased from 138,000 tons to 250,000 tons, or an increase of only 81 percent. After 1957, steel production and fluorspar consumption both decreased owing first to the recession of 1958, and then to the steel strike of 1959. The lag in consumption of fluorspar in steel manufacture, coupled with a tremendous increase in hydrofluoric acid production during recent years, has caused steel to drop into second place as a consumer of fluorspar. Figure 5 shows changes in the quantities of fluorspar used by various consumer groups in recent years. [14] ILLINOIS FLUORSPAR 15 W 300 z o 200 a z < 01 o KEY Acid fS'l'.'.i Ceramic Steel I I Other & k 1940 1950 YEARS 1952 1956 Fig. 5 - United States consumption of fluorspar, 1941-1959, by use The hydrofluoric-acid industry has long been an important consumer of fluor- spar, but with the phenomenal growth of the industry in the last several years the quantity of fluorspar used for this purpose has been rapidly increasing. In only the last decade there has been a three-fold increase in the industry's consumption of fluorspar. In 1959, acid manufacture accounted for about 55 percent of the total fluorspar consumed. Much growth of the hydrofluoric-acid industry stems from the widening use of fluorine chemicals for industrial and other uses. Fluorine compounds are used for insecticides, wood preservatives, welding fluxes, antiseptics, as a concrete hardener, tooth decay preventive, synthetic optical crystals, and many other purposes. Another reason for the marked expansion in hydrofluoric-acid production is the important role that acid plays in the production of aluminum. The aluminum industry uses hydrofluoric acid to manufacture aluminum fluoride and synthetic cry- olite; about 58 pounds of aluminum fluoride and 47 pounds of cryolite, having a combined equivalent of 148 pounds of fluorspar, are used for each ton of aluminum. An increase in aluminum output from 623,000 tons in 1948 to 1,566,000 in 1958 had a pronounced effect on the hydrofluoric-acid production. The use of fluorspar in ceramics and for miscellaneous purposes has not fluctuated much in recent years. In ceramics, fluorspar is used principally in the manufacture of opal, opaque and colored glass, and to make various colored ena- mels for coating metal and metalware and ceramic tiles. Miscellaneous uses for spar are as an artificial abrasive and as an additive in Portland cement, rock wool, basic refractory cements, and buff face bricks. Ceramics and miscellaneous uses normally account for about 11 percent of total annual consumption. Fluorspar is marketed in three grades — acid, ceramic, and metallurgical — depending principally on its calcium fluoride content, on the presence of certain mineral impurities, and to some degree on particle size. Table 1, showing the various uses to which fluorspar of the different grades is put, also reveals that there is considerable overlapping of grades in some uses, as, for example, in 16 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Table 1. - Fluorspar (Domestic and Foreign) Consumed in the United States by Grades and Industries, 1957-1958, in Short Tons 3 Grade and industry Consumption 1957 Consumption 1958 Acid grade: Hydrofluoric acid Glass Enamel Welding rod coatings No n ferrous Special flux "| Ferroalloys I Primary aluminum J Total 328,672 3,221 118 819 131 1,763 334,724 258,935 3,916 125 810 25 2,137 265,948 Ceramic grade: Glass Enamel Welding rod coatings Nonf errous Special flux \ Ferroalloys J Total 27,899 4,314 1,154 118 7,983 41,468 25,123 4,776 200 5,339 1,134 36,572 Metallurgical grade: Glass Enamel Welding rod coatings Nonf errous Special flux Ferroalloys V Primary magnesium] Iron foundry Basic open-hearth steel Electric-furnace steel Bessemer steel Total 1,017 800 343 5,123 2,723 15,382 212,304 30,376 428 268,496 824 88 164 1,773 1,467 12,883 150,328 24,033 147 191,707 All grades Hydrofluoric acid Glass Enamel Welding rod coatings Nonf errous Special flux Ferroalloys Primary aluminum ~1 Primary magnesium/ Iron foundry Basic open-hearth steel Electric-furnace steel Bessemer steel Total 328,672 32,137 5,232 2,316 5,372 7,959 1,981 2,529 15,382 212,304 30,376 428 644,688 258,935 29,863 4,989 1,174 7,137 257 1,691 2,790 12,883 150,328 24,033 147 494,227 Source: United States Bureau of Mines Glass, enamel, and other (including welding rod coatings, nonferrous, special flux, and ferroalloys), partly estimated from sample canvass of consumers who accounted for more than 95 percent of total usage in 1957. ILLINOIS FLUORSPAR 17 Table 2. - Fluorspar Shipments from Illinois Mines Year Tons Value Year Tons Value 1930 44,134 $ 836,473 1931 28,072 468,386 1932 9,615 156,279 1933 36,075 543,060 1934 33,234 567,396 1935 44,120 685,794 1936 82,056 1,525,606 1937 78,664 1,730,585 1938 35,368 751,227 1939 75,257 1,638,693 1940 104,698 2,313,747 1941 133,333 3,047,247 1942 161,949 4,306,750 1943 198,789 6,292,789 1944 176,259 5,954,991 1945 147,251 $5,014,807 1946 154,525 5,493,642 1947 167,157 6,148,654 1948 172,561 6,322,246 1949 120,881 4,621,733 1950 154,623 6,110,765 1951 204,328 9,294,703 1952 188,293 9,481,223 1953 163,303 8,567,026 1954 107,830 5,989,219 1955 166,337 7,838,471 1956 178,254 8,469,450 1957 169,939 8,827, 171 a 1958 152,087 a 7,931,000 a a Subject to revision. glass making and in enamel, where all three grades find some use. Conversely, for making steel or hydrofluoric-acid only one grade is suitable. Metallurgical fluor- spar used in steel furnaces must be of gravel or lump size to perform satisfactorily as a flux. The consumers of acid grade fluorspar require a product that is finely ground and of high purity. PRODUCTION TRENDS United States production of fluorspar rose from 234,000 tons in 1940 to 301,000 tons in 1950 and to almost 330,000 tons in 1956 and 1957. By 1958 it had fallen to 320,000 tons and in 1959 was only 178,000 tons. The growth in fluorspar production has not paralleled the increase in consumption because of the foreign im- ports. The effect of the imports has been only partially offset by tariffs and by the United States Government stockpiling program. United States reserves of fluorspar were estimated in 1956 by the United States Geological Survey to be 22.6 million tons (3), an amount approximately 28 times the 1957 production. Reserves in the Illinois-Kentucky fluorspar district are estimated at 8 million tons. Of the total fluorspar produced annually within the United States, each year Illinois accounts for about half. In 1958, Illinois led in production with 152,087 tons, followed by California with a production of 59,464, Montana with 53,654, and Kentucky with 25,861 tons. Other producing states during 1958 were Utah with 16, 109 tons and Nevada with 12, 338 tons. Table 2 gives the annual production by Illinois mines from 1930 through 1958. The Illinois fluorspar output comes from numerous mines ranging in size from those whose production is only a few hundred tons per year to those producing tens of thousands of tons annually. In general, the output of the small mines is sold to larger operators who have facilities for upgrading the raw mine product, but in some instances, the small mines sell directly to markets that can use fluorspar in the larger sizes and of purity obtained through hand sorting. The larger producers op- erate mills where the run-of-mine material is crushed or ground and processed to remove impurities either by gravity means or by flotation. 18 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Table 3. - Fluorspar (Domestic and Foreign) Consumed in the United States, by States, in 1957-1958, in Short Tons 3 State 1957 1958 b Alabama, Georgia, North Carolina and South Carolina 12,268 10,155 C Arkansas, Kansas, Louisiana, and 29,096 12,621 17,607 747 120,944 698 62,974 25,307 3,828 d 29,197 5,330 324 14,594 3,738 13,832 58,360 670 55,164 499 15,848 5,924 6,770 Total 644,688 494,227 Source: United States Bureau of Mines. Consumption partly estimated from sample canvass of consumers who accounted for more than 95 percent of total usage in 1957. Alabama, Georgia, and South Carolina. Iowa, Minnesota, and Wisconsin. Oklahoma 88,622 California 35,985 Colorado and Utah 22,944 Connecticut 585 Delaware and New Jersey 79,275 Florida, Rhode Island, and Virginia 1,059 Illinois 97,454 Indiana 33,451 Iowa, Minnesota, Nebraska, South Dakota, and Wisconsin 4,948 Kentucky 30,111 Maryland 5,494 Massachusetts 443 Michigan 20,453 Missouri 4,340 New York 20,204 Ohio 72,151 Oregon and Washington 1,686 Pennsylvania 82,882 Tennessee 1,058 Texas 21,221 West Virginia 8,054 Undistributed - Large quantities of fluorspar formerly were cleaned by jigs. At present most mills clean fluorspar in gravel size by heavy-media separation. The coarse product of this operation can be used as metallurgical spar, but more often is further clean- ed and up-graded by flotation. The flotation process yields a finely ground concentrate of high purity and uniform quality that is used in acid manufacture, ceramics, or other applications where the fine size is not a disadvantage. It is not generally suitable for open- hearth steelmaking, but in some instances briquetted or pelletized fine material forms a suitable product for such use. Almost 90 percent of the finished fluorspar produced in Illinois is shipped in the form of flotation mill concentrates. About 60 percent of the fluorspar shipped from Illinois mines normally goes into the manufacture of hydrofluoric acid. Steel manufacture and ceramic use accounted for about 8 percent each, and the remainder serves miscellaneous purposes. ILLINOIS FLUORSPAR 19 MARKETING Shipments of fluorspar from Illinois mines generally enter the market through one of three principal channels. Some mines are captive operations whose output normally goes directly to the consuming plants of the parent organization. Producers having no affiliations usually sell the major portion of their product through a sales agency or other organization which maintains contact between the producer and po- tential consumers. A third way in which fluorspar may be marketed is by contract or by direct contact between the producing firm and the purchaser. The output of small mines is mainly sold to larger producers who sell it directly or process it before it enters the market. Because of its many uses, fluorspar is consumed in many places throughout the United States. At least 37 states reported consumption during 1957 and 1958 as shown in Table 3. Those states containing steel and hydrofluoric acid producing plants account for almost 90 percent of total fluorspar consumption. Figure 6 shows the location of major steel plants and hydrofluoric acid plants in 1957. A concentration of these plants along the Great Lakes and inland waterways is apparent. Of the total fluorspar used in the United States during 1958, five states — Delaware, New Jersey, Illinois, Pennsylvania and Ohio — accounted for 60 percent, Each of these five states produces steel, and steel production consumes more than half of the total fluorspar used within these states. In addition to steel plants, all these states also contain hydrofluoric-acid plants. The proximity of the Illinois fluorspar deposits to the major consuming areas places them in an extremely favorable position to serve the entire region. fV KEY Sleel m Hydrofluoric Acid / Illinois Fluorspar Region Fig. 6 - Location of steel and hydrofluoric-acid plants, 1957 20 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Fluorspar may be moved from mine to market in any of several ways. Ship- ments of the larger metallurgical-grade sizes of fluorspar commonly are made in open-type railroad cars or open barges; bulk shipments of the finer sizes are trans- ported in boxcars or covered hoppers. Finely ground fluorspar also is shipped in paper bags usually holding 100 pounds. Truck shipments are either in bulk or in bag. Loading docks on the Ohio River, a short distance from the fluorspar opera- tions, are used to transfer fluorspar to barges for shipment up or down stream. Barges of several hundred ton capacity are used for such .shipments. SUMMARY Production of fluorspar in Illinois and other states is currently limited by competition from foreign imports. Production figures in Table 2 indicate that Illinois possesses a capacity to produce far more fluorspar than is currently produced. Should an interruption occur for any reason in the large quantities of fluorspar entering the United States from outside sources, United States industry would quickly become critically dependent upon the output Illinois can provide. Sudden demands for in- creased production, however, can be met by the mining industry only if productive capacity is maintained in a high degree of readiness. PART III USES OF FLUORSPAR AND FLUORINE CHEMICALS DIRECT USES OF FLUORSPAR Hydrofluoric Acid Manufacture The chemical industry, the largest consumer of fluorspar, in 1959 (23) used 324, 500 tons of acid spar, or 55 percent of the total fluorspar consumed. For the same year, on the basis of 2 . 4 tons of spar yielding 1 ton of acid, the production of hydrofluoric acid was estimated at 135,000 tons (29), almost a 300 percent in- crease in a decade. As hydrofluoric acid is a key chemical in a rapidly growing fluorine chemical industry, its future is most promising. The direct and indirect uses are discussed under uses of fluorine chemicals. Two types of hydrofluoric acids are commercially available — aqueous and anhydrous. The aqueous acid is a water solution of hydrogen fluoride, whereas commercially the anhydrous product is labelled as such when the moisture content is very low, usually less than 5 percent. The anhydrous product is known in trade language as HF or anhydrous HF (also AHF), or by the misnomer of anhydrous hydro- fluoric acid. From a chemical standpoint these two products exhibit marked differ- ences in properties and may be considered as two different chemicals. Both are made by the same basic reaction, namely by the reaction of acid spar with sulfuric acid in heated kilns or retorts. CaF2 + H 2 S0 4 »► 2 HF + CaS0 4 For many years aqueous hydrofluoric acid has been prepared by absorbing the hydrogen fluoride gases from a retort in water in suitable lead cooling and absorb- ing towers. By recycling or redistilling the absorption liquors various strengths of acid up to 60 percent were prepared. Acids below 60 percent are shipped in lead, rubber, and more recently in polyethylene containers; for acids of 60 percent and higher, steel containers are used. In modern practice, aqueous acid. is prepared by dilution of the anhydrous product to the desired strength, usually at the time a pur- chase order is received. This has simplified the storage problem because the an- hydrous product can be stored in steel. Anhydrous acid is made by the same general reaction but under more rigidly controlled conditions (19, 29). The generator is ordinarily a horizontal steel kiln that revolves and is heated externally, usually by direct fire. Finely ground acid spar is mixed with a slight excess of strong sulfuric acid in a hopper and fed con- tinuously into one end of the generator. A large vent pipe serves as a collector for the HF and other gaseous products. At the opposite end of the generator, calcium sulfate as a waste product is usually expelled by a screw drive into water. The composition of the hot gaseous mixture from the generator is about 95 percent HF, 4 percent air, and 1 percent impurities such as H2SO4, SiF^, H2O, CO2, and SO2. Aluminum fluoride, synthetic cryolite, and some other fluorides can be prepared directly from this gas. For anhydrous acid, the gas is put through a purification process. The gaseous mixture is cooled and absorbed countercurrently in a tower with a weak cycle sulfuric acid to a 70 percent HF concentration. Upon distillation of the concentrated acid, the water remains with the sulfuric acid residue, and the HF is collected as a distillate. Redistillation in a suitable column separates the low-boiling SiF 4 , CO2, and SO2 from the higher boiling HF (boiling point 19° C) . [21] 22 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 To avoid contamination of the atmosphere, the exit gases may be passed into water absorption towers where the SiF^ is converted into fluosilicic acid (I^SiFg) . This same acid is recovered on a tonnage basis as a low-cost by-product in the phos- phate fertilizer industry. The anhydrous HF is stored in steel containers, and a purity as high as 99.95 percent HF is available. The current price is 18 cents per pound in carload lots (April 1960). It must always be remembered that hydrofluoric acid is a highly corrosive and hazardous chemical. However, in view of the tremendous tonnages that are being produced, it is obvious that the handling of it has been perfected to a routine operation. In the manufacture of 1 ton of HF, about 5 tons of fluorspar and acid are re- quired, and about 4 tons of calcium sulfate is formed as waste product. About 2.4 tons of acid spar is required to produce a ton of HF, according to the Bureau of Mines; however, it is suspected that some plants may use approximately 2.2 tons and recent technological advances may lower the figure still further. The sulfuric acid is usually a commercial 96-percent grade, and a 5 to 10 percent excess is used. As the quality of the acid fluorspar is very important, the specifications are quite rigid. A typical specification is not less than 97 percent CaF2, not more than 1 percent Si02, 0.05 percent S, 1 percent moisture, and a min- imum of calcium carbonate. The relation of CaF2 content to HF yield is obvious. Reasons for the other items are: each part of S1O2 causes a loss of 1 1/3 parts of HF as SiF4, sulfur causes process difficulties, moisture affects efficiency, calcium carbonate wastes sulfuric acid, and the CO2 causes foaming. It is essential also that the spar be finely ground as it influences the rate of reaction with sulfuric acid. Metallurgy Steel Agricola (16) in 1556 mentioned the use of fluorspar as a flux in metallurgy. Owing to this early use the name fluorspar was coined from the Latin, literally meaning the rock that flows. Today the steel industry is the second largest user of fluorspar, consuming about 40 percent (33) in the form of metallurgical spar. The spar functions as a fluxing agent and may assist also in the refining process. It is used in the basic open hearth, electric furnace, and Bessemer steel processes. The Bessemer pro- cess, with a consumption of about 500 tons per year, is a minor consumer. Basic open-hearth steel (25) normally consumes about 80 percent of the metallurgical spar. The spar in granular form is spread on the furnace floor at the start; after the smelting operation is under way additional spar is shoveled into the furnace in such a way as to be uniformly spread over the slag. Depending on economic conditions, as much as 10 pounds per ton of steel may be used, but the average is about 5 pounds. Annual records show that the average per ton has been decreasing. The spar gives fluidity to the slag, thus resulting in a better steel recovery and lower fuel cost. It also causes the solid lime lumps to dissolve more rapidly in the slag so that a maximum amount of lime is available for the most ef- fective removal of sulfur and phosphorous from the metal. The furnace gases, as in most metallurgical and foundry processes using fluorspar, may contain considerable quantities of SiF^ formed by the reaction of the spar with silica (Si02) . Severe cases of air pollution by such fluoride fumes are known (3), causing damage to crops and animals, thus necessitating an expensive ILLINOIS FLUORSPAR 23 fume catching system. Perhaps in time a process will be developed that will recover the lost fluorine for reuse as a flux. Electric furnace steel uses about 14 to 40 pounds (17) of spar per ton of steel, Only about 10 percent of the metallurgical spar is consumed in this industry. As the demand for special steels is increasing it is expected that the demand for spar also will increase. This industry prefers the higher grade metallurgical spar. Typical metallurgical grade specifications are a minimum of 60 percent ef- fective CaF2, not more than 0.30 percent sulfide sulfur nor more than 0.25 to 0.50 percent lead. Silica is objectionable because one part requires 2.5 parts of CaF2 to flux it; therefore, the silica percentage is multiplied by 2.5 and deducted from the actual CaF2 content to get the effective CaF2- Seldom more than 5 percent sil- ica is allowable. Barite (BaSO^ is objectionable because it decreases fluidity of the slag. Most steel producers purchase the spar in a gravel size passing through a 1-inch to 1^-inch mesh screen and not more than 15 percent fines. Some spar pro- ducers can merchandise a pellet the size of a peach seed made from flotation con- centrates. Occasionally other sizes may be specified. Foundries In 1959 about 13,000 tons of metallurgical grade spar was used as a flux by iron foundries, primarily in the production of fine grade castings, as for example automotive engines. The spar causes the charge to melt more rapidly, aids in re- moval of sulfur and phosphorous, gives a more liquid slag, minimizes lime accumu- lation at air inlets, and gives a cleaner drop at the end of the pouring period. Cleaner, more malleable, and higher tensile strength castings are reported. An average of 15 to 20 pounds of spar per ton of metal is added to the cupola as lumps, and about 3 percent of ground spar per ton of metal may be added to the ladle. The basic open hearth steel specifications on spar apply to foundry practice. In the cupola, a lump material ranging from nut size and up is used, whereas in the ladle a ground material is preferred. Domestic mills provide 1 by 1^-inch foundry lump in 60 percent effective grade. Most of the larger sized lump is hand sorted. Ferroalloys A ferroalloy is a special alloy of iron with a high proportion of another ele- ment such as chromium, manganese, molybdenum, silicon, titanium, tungsten, van- adium, and others. These alloys are identified in commerce as ferrochromium, fer- romanganese, and so on. For the most part, they are added in limited amounts to iron and steel melts to function as 1) scavengers and deoxidizers, and 2) for con- ferring special properties (such as toughness, hardness, corrosion resistance) on a finished steel. Most of them are produced in an electric furnace, and fluorspar is added as a fluxing agent. The amount and grade of fluorspar added varies widely from plant to plant, type of steel produced, and economic conditions. The consumption will vary from 1 to more than 200 pounds per ton of ferroalloy. A fine size is desired for uniform distribution in the furnace. All grades of spar are used, although the higher grades are preferred. Special Fluxes The category of special fluxes includes a variety of fluxes used in the re- fractory, aircraft, and welding industries, and in some chemical processes. All 24 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 grades of fluorspar are used, and a ground material is desired. In 1957 about 8,000 tons, or about 1.2 percent of the fluorspar consumed, was channeled to the afore- mentioned customers. Welding Rod Coatings Fluorspar, along with many other fluorides, finds extensive use in welding fluxes and welding rod coatings. The function of a flux in welding is to act as a surface cleansing agent and also to protect the surface from oxidation or burning. Generally, the flux is prepared by melting the components to a homogeneous mix- ture, after which it is cooled and then ground. For coating welding rods a binder is added. When fluorspar is used, the fluorspar content in the composition ranges from 2 to 50 percent. About 50 percent of the fluorspar used in coatings is ceramic grade, 35 per- cent is acid spar, and the remainder is metallurgical grade. A finely ground mater- ial is specified. Primary Aluminum (15, 24) Fluorspar is added to the cryolite bath of the aluminum reduction cell as a flux to lower the freezing point. In normal operation, the molten electrolyte con- tains 6 to 10 percent CaF2 and the temperature is held at 950 to 980° C. After a cell is operating, very little fluorspar as such is needed to balance the slight me- chanical losses. About 600 tons of spar was used in this manner in 1957. A ground, acid grade spar is preferred because impurities affect the quality of the aluminum metal and the efficiency of the cell. Iron and silicon contaminate the metal and also form volatile fluorides. Lead and zinc appear in the metal, and sulfur reduces cell efficiency and also forms sulfur gases. Smelting: Magnesium, Zinc, and Other Metals A small amount of ground, metallurgical spar is used as a flux in magnesium reduction. It is likely that some spar also is used in resmelting and casting of the metal . Zinc smelting (private communication, 1959, William Coolbaugh, metallur- gist) by the horizontal retort process is benefitted by the addition of fluorspar. The furnaces are charged with a mixture of 16 pounds of powdered, ceramic spar per ton of sintered zinc ore. The spar serves as a flux and increases the yield and produc- tion of zinc metal from the ore. For this purpose, a spar of 88 to 90 percent CaF2 and not more than 1 to l| percent moisture are satisfactory. Minor amounts of fluorspar are reported to be used as a flux in the smelting and refining of antimony, copper, chromium, gold, lead, silver, tin, nickel, and others . Outside of magnesium, consumption of fluorspar by the preceding nonferrous metals was about 7,000 tons in 1958. Metallurgical spar is generally specified, although some of the acid and ceramic grades also are used. Ceramics Glass The glass industry is a stable consumer of fluorspar, demanding about 30,000 tons per year. The spar is used as a flux and opacifier. Clear glass has the least ILLINOIS FLUORSPAR 25 amount of spar in its formulation, whereas opal and colored glass demand a larger quantity to obtain opaqueness. Depending on the glass desired, 50 to 500 pounds of ground spar are used for each 1000 pounds of sand in the glass batch. Examples of opal glass are lamp bulbs, globes, shades, toilet and medicinal containers, and many other items. Frequently other fluorides are added along with spar in glass formulations . About 85 percent of the spar used by the glass industry is ceramic grade; the remainder is almost entirely acid spar. A ground fluorspar is required and is classified as coarse (55 percent passing a 100-mesh sieve), fine, and extra fine. A typical specification for No. 1 ceramic is not less than 95 percent CaF2» not more than 3 percent Si02, 1 percent CaCOg, and 0.12 percent Fe20o- Only traces of lead, zinc, barium, and sulfur are permitted. Iron gives a green or yellow tint. As the calcite is converted to lime in the glass furnace, an excess will cause brittleness of the glass and also difficulty in formula control. When specifications differ from the above, most fluorspar producers can meet the demands of the cus- tomer. Enamel Enamels and glazes are low-melting glasses used for coating cast iron, steel, and other metals. Fluorspar and other fluorides serve as fluxes in lowering the melting point of the glass melt and also give opacity to the finished coatings. About 5, 000 tons of fluorspar per year are used in this manner. Products of this industry are prefabricated metal buildings and store fronts, bath tubs, lavatories, sinks, refrigerators, stoves, signs, artware, and many other common items . The fluorspar or fluoride content of enamels ranges from to 15 percent. A small percentage will lower the melting point, but opacity requires a higher per- centage, usually 6 percent. The ceramic grades are generally specified, although small amounts of the other grades are purchased. Specifications on the spar for enamel or glazing purposes are much the same as for glass, and for the same reasons. However, there is a tendency to specify a higher quality ceramic spar and a finer screen size. Water Fluoridation One part per million of fluorine in drinking water is the desired concentra- tion in the fluoridation of municipal water supplies. Various fluorine chemicals are being used for fluoridation and not until recently was it possible to use fluor- spar, the lowest price fluoride available. The very low solubility of fluorspar in water was the deterrent. In the late 1950 's Maier and Bellack (22), Division of Dental Public Health, United States Public Health Service, Washington, D. C, developed a controlled fluoridation process, based on the reaction of alum salts with fluorspar to form soluble fluoride. Since 1956 the demonstration plant at the Bel Air, Maryland, water supply has been proving the practicability of the process. In 1958 a similar plant was installed at Rosiclare, Illinois, with equal success. A finely ground spar with a high CaF2 content is required. In terms of cer- amic grade spar (95 percent CaF2), it is estimated that 18 pounds of fluorspar will fluoridate one million gallons of water. Regarding cost (11), fluoridation with fluorspar is estimated at $0.03 per capita per year as against $0.10 with other presently used fluorides. 26 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Miscellaneous Portland Cement (1, 26) It is common practice in Germany (13) in manufacturing Portland cement , to add 1 to 5 percent of low grade fluorspar to the raw cement mix . The fluorspar lowers the sintering temperature and acts as a mineralizer. In the United States very little spar is used in the cement industry. However, domestic cement man- ufacturers may benefit from research now in progress on the use of fluorspar as a mineralizer in promoting formation of tricalcium silicate at lower clinkering tem- peratures. The success of this will mean lower fuel costs, increased kiln capacity, and a longer life for the kiln liner. Some western cement firms are adding fluorspar to their raw material as an aid in the volatilization of potassium and sodium salts during the clinkering pro- cess. Before the development of the domestic potash deposits, the flue gases of the cement industry were an important source of potash. It appears that a finely ground spar of the low metallurgical grade and lower is used. Calcium Cyanamide (2, 18) Calcium cyanamide (CaCN?) is produced by reacting nitrogen with calcium carbide. In the Frank-Caro electrothermal process (2) about 2 to 3 percent of finely ground fluorspar is added to the calcium carbide to lower the fusion point and increase the velocity of the reaction. The fluorspar must have less than 0.1 percent moisture and must contain a minimum of 90 percent CaF2- Annual produc- tion of calcium cyanamide in North America is more than 200,000 tons. It is used as a fertilizer, cotton defoliant, and in the manufacture of melamine resins, sulfa drugs, explosive propellants, and other synthetic organic nitrogen chemicals. Mineral Wool The presence of 1 to 2 percent of acid or ceramic grade spar in certain rock- wool melts will give greater fluidity at a given temperature and a smaller fiber diameter (21) to the final product. Brick Stain Inhibitor The principal contributor to yellow, green, or brown efflorescent stain on light-colored face brick is vanadium. A small percentage of fluorspar added to the clay mix will inhibit this efflorescence to varying degrees, depending on the clay (12). Binding Material A small amount of fluorspar is used as a binder in abrasives and high-tem- perature brick. Optical Lenses Because clear fluorspar has a low index of refraction, high ultraviolet transmission, and low dispersion, it is used in optical lenses for scientific in- struments. As clear, natural crystals are very rare, large artificial crystals (28) are now produced by controlled cooling of a melt of semi-optical grade of spar. ILLINOIS FLUORSPAR 27 To reduce reflection on optical lenses and prisms, a very thin film of such fluorides as LiF, MgF 2 , CaFn, and others can be used (27). Dental Cements Some dental cements in their composition contain 10 to 15 percent fluorine (27) as CaF 2 and NaF. Jewelry Colored spar finds some use as a gemstone in jewelry and stone ornaments. Wealthy Romans of 2, 000 years ago treasured their goblets of fluorspar from Parthia. The Mound Builder aborigines in America carved crude figures from fluorspar. Many beautiful goblets, urns, and vases of native spar were cut and polished in the 1700's and 1800's in England. A small amount of very pretty jewelry is still pro- duced near Castleton in the Derbyshire District of central England. USES OF FLUORINE CHEMICALS Hydrofluoric Acid The fluorine chemical produced in largest quantities is hydrofluoric acid (HF), an important chemical for two reasons: 1) it is used in nonfluorinating pro- cesses as a catalyst, reaction medium, metal pickling agent, and in many other ways, and 2) it is a key chemical in almost all fluorine chemical processes. Stuewe (29) has written a review on the manufacture and uses of HF. Aqueous hydrofluoric acid is used in the manufacture of many inorganic fluorides and acid fluorides; in frosting, etching, and polishing of glass; as an antiseptic in breweries and distilleries; electroplating; cleaning of copper and brass; pickling and galvanizing metals; removal of efflorescence from stone and brick; extraction of tantalum and columbium; in the making of filter paper and carbon electrodes; removal of silica from graphite, and in acidizing oil wells to increase oil production. Anhydrous HF is a versatile and useful chemical. Not only can it advan- tageously replace aqueous acid in many instances, it has many special applica- tions where it is used in large tonnages. It is especially useful in organic chem- istry for fluorination, hydrofluorination, polymerization, esterification, catalysis, alkylation, reaction medium, nitration, sulfonations, and many other processes. The uses and consumption of HF in 195 7 are given in table 4. About 75 percent of the HF consumed was used in the manufacture of four commodities. The large HF consuming industries for the most part produce their own HF, with the result that only about 25 percent of the HF consuming market is open to merchant producers. Aluminum Fluoride and Synthetic Cryolite Practically all of the aluminum fluoride (AIF3) and most of the synthetic cryolite (Na^AlFg) are used as a flux and electrolyte in the production of primary aluminum. About 58 pounds of AIF3 and 47 pounds of Na^AlFg are used per ton of primary aluminum (32). In the electrolytic refining of primary aluminum to super pure aluminum, the electrolyte is essentially a mixture of cryolite, aluminum fluor- ide, and frequently barium fluoride (24). 28 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Table 4. - Consumption of HF in 1957 a Use HF (short tons) Percent of total Aluminum fluoride 40,000 29.6 Fluorocarbons 38,500 28.5 Uranium production 16,000 11.8 Synthetic cryolite 13,000 9.6 Conversion of salts 7,500 5.6 Stainless steel 7,000 5.2 Petroleum alkylation 6,000 4.5 Special metals 3,000 2.2 Etching and frosting 2,000 1.5 Others 2,000 1.5 Total 135,000 100.0 a Source: Stuewe (1958). Aluminum fluoride generally is prepared by the reaction of HF with alumina as in equation [l] . [1] 6 HF + A1 2 3 *- 2 A1F 3 + 3 H 2 If synthetic cryolite is desired, an alkaline solution of alumina is reacted with HF as in equation [2]. [2] 6 HF + Al(OH) 3 + 3 NaOH »► Na 3 A1F 6 + 6 H 2° An alternate source of these fluorides, especially synthetic cryolite, is the silicofluoride route. This will become increasingly important as the phosphate fertilizer industry produces large tonnages of low-cost silicofluoride by-product. A small amount of aluminum fluoride and appreciable quantities of synthetic cryolite are used as fluxes and opacifiers in ceramics and in welding fluxes. Cry- olite also is used as an insecticide. Fluorocarbons The terms fluorocarbons and fluorochemicals have been coined to define carbon compounds containing fluorine. These materials are used as refrigerants, aerosols, plastics, dielectrics, lubricants, coolants, wetting agents, fire ex- tinguishers, and for many other purposes. Production of these useful products is a major industry, and future growth is most promising. In 1957, some 38,500 tons of HF was used to produce 200 million pounds of fluorocarbons valued at 60 to 75 million dollars. Anticipating future growth, fluorocarbon production capacity already is rated at 410 to 490 mil- lion pounds (9). Producers are anticipating a fluorocarbon market of 230 million pounds in 1960 and 275 million in 1962. Stuewe (29) estimates that 67,000 tons of HF will be used in this industry in 1963. The refrigerant and aerosol industries each consume about 45 percent of the fluorocarbon production, plastics 3 to 5 per- cent, and miscellaneous, including export, the remaining percentage. ILLINOIS FLUORSPAR 29 Almost all of the fluorocarbons are produced by the same general reaction. The basic reaction was discovered in 1892 by Swarts, a Belgian chemist, and was developed commercially in 1930 by Midgley and Henne for the manufacture of the Freon refrigerants. The reaction, expressed in its simplest terms, involves the re- placement of chlorine in a suitable organic chloride with fluorine by means of a metallic fluoride or anhydrous HF. This is illustrated by the preparation of dichloro- difluoromethane (F-12), CCI2F2. In practice, carbon tetrachloride and anhydrous HF in a definite ratio are fed continuously to a heated reactor containing antimony 3 CC1 4 + 2 SbF catalyst ^ 3 cd^ + 2 SbCl 3 trifluoride and a catalyst. The volatile reaction products pass into a distillation column where the fluorocarbon is separated. By varying reactor conditions and using other chlorinated methanes and ethanes, a large group of fluorocarbons can be produced. The fluorocarbon work horses, or those produced in largest amount, are CC1 2 F 2 , CCI3F, and CHC1 2 F. Approximately 1 ton of HF will produce 3 tons of fluorocarbon. Small amounts of fluorocarbons and derivatives are prepared also by the Simons electrochemical process (27, p. 414). A cracking or pyrolysis process (20) on CHC1F 2 yields tetrafluoroethylene for teflon plastic manufacture, octafluorocyclobutane, and other fluorocarbon de- rivatives . As the chemical names of the fluorocarbons are rather cumbersome for every- day usage, industry has developed general trade names and code symbols. The first commercial fluorocarbons were produced by the du Pont Company and were tradenamed Freon. Examples are F-ll , CCI3F; F-12, CC1 2 F 2 ; F-13, CC1F 3 ; F-14, CF 4 ; F-21, CHC1 2 F; F-22, CHC1F 2 ; F-112, CC1 2 FCC1 2 F; F-113, CC1 2 FCC1F 2 ; F-114, CC1F 2 CC1F 2 ; F-115, CC1F 2 CF 3 ; and others. Other companies retained the same code numbers but prefixed their trade names such as Genetron (General Chemical Company), Isotron (Pennsalt Manufacturing Company), and Ucon (Union Carbide Chemicals). Refrigerants The fluorocarbon gases are ideal as refrigerants because they are nontoxic, odorless, stable, noncorrosive, and have a low fire hazard. They are available in a wide range of boiling points, thus enabling refrigeration engineers more ef- ficiently to match the machine to the application. For instance, demands differ widely between air conditioners (home, automobile, and commercial), refrigerators, and freezers. The average home refrigerator and cooler are charged with 1 to 2 pounds of refrigerant. About 75 percent of the refrigerant sales are for replacement purposes. With the trend toward hermetically sealed units, the demand for replace- ment gas will decrease. However, the market for air conditioning is far from the saturation point. Aerosols Fluorocarbons were first used as inert propellants in the "bug bombs" pro- duced for rapid fumigation purposes in World War II for the Armed Services. Out of this grew the fabulous aerosol industry which in 1958 (6) packed more than 100 products in 470 million units (dispensers) valued at 470 million dollars. Hair sprays, shaving lather, room deodorants, insect sprays, coatings, colognes, and perfumes accounted for more than 80 percent of the units sold. It was reported in 1957 that more than 60 percent (7) of the units were pressurized with an equivalent of about 43, 000 tons of fluorocarbons. 30 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 The most important fluorocarbon propellants are F-12 (CCI2F2) and F-ll (CCloF) and mixtures thereof. Some use is made of fluorocarbons F-22 (CHCIF2) and F-114 (CCIF2CCIF2) to solubilize certain ingredients and to produce certain effects . Producers of fluorocarbons still consider the aerosol field as an area of expansion. A manufacturer has estimated a market of 720 million aerosol units in 1962 and at least a billion units by 1968. Some producers agree that approval of fluorocarbons for food use by the Federal Food and Drug Administration would open a new market area in spite of possible severe competition from lower cost gases . Plastics Teflon and Kel-F are the most important fluorinated plastics used in industry; in chemical language they are known as tetrafluoroethylene (CF2=CF2)x an d tri- fluorochloroethylene (CF2=CC1F) X polymers, respectively. The basic raw materials are F-22 (CHC1F 2 ) and F-113 (CC1 2 FCC1F 2 ) . These plastics are nonflammable, insoluble in organic solvents, very stable to chemical agents, possess high thermal stability, and are excellent dielectric materials. They are fabricated into special gaskets, packings, pump liners, tubing, pipe, wire and cable coating, filter cloths, and many other items where their high cost is justified by the application. As teflon has a waxy surface with a low friction factor, it is molded into bearings having the property of natural lubrication, and it is used also as an anti sticking coating on rollers and pans in food processing. Kel-F is quite transparent and is thermo- plastic . Military agencies in the search for materials for use under severe conditions have stimulated plastic manufacturers to develop some special plastics. As these are costly, their production is small. Other Special Uses A new development is being explored in which fluorocarbon gases will be used as foaming agents in the manufacture of urethane solid foams that have su- perior insulating properties. A stain repellant and fluorocarbon derivative, com- mercially known as "Scotchgard, " is being used for coating furniture fabrics and men's suits. A variety of fluorocarbon liquids, oils, and greases are available as coolants, dielectrics, and lubricants. Fluorocarbon surfactants, that is, agents that lower surface tension, are being used as levelling agents in polishes, oil-water mixtures, electroplating, etc. Bromotrifluoromethane (CBrF3) and dibromodibromomethane (CBr2F2) are used as special fire extinguishers. Some coal tar dyes that contain fluorine find limited application as bright colors for cotton. Medical science is using fluorosteroids for the treatment of arthritis and in the form of an ointment for skin irritations. Various organic fluorine compounds are being investigated extensively in cancer chemotherapy. Fluoethane (CF3CHCI Br) and Fluoromar (CF3CH2OCH2 = CH2) are being tested extensively as new an- esthetics. Some tranquilizers and a diuretic contain fluorine in their composition. Indoklon (CF0CH2OCH2CF3) is being tested as a pharmacoconvulsive agent in mental therapy. A fluorinated compound is being used in an effort to control the lamprey pest which has practically destroyed commercial fishing in the Great Lakes. Some in- terest in the use of fluoroorganic materials as insecticides, weed killers, shock absorber liquids, and selective solvents has been reported. ILLINOIS FLUORSPAR 31 Petroleum Alkylation During World War II the HF process for producing high-octane blending components for gasoline was developed. The HF functions as a catalyst for the conversion of olefins and isoparafins into an alkylate that consists of a mixture of isomers of heptane, octane, etc. As the process is catalytic, very little make up HF is needed to maintain the reactors at their capacity. Unconfirmed reports in- dicate that some reactors use 50 tons of anhydrous HF. Although the sulfuric acid process still produces 80 percent of the alkylate, the HF process is showing a small, steady increase. Atomic Energy Uranium 235, a key nuclear fuel component in atomic energy, is found in a very small amount along with a preponderance of uranium 238 in natural occur- ring uranium ore. The separation and concentration of the U^35 isotope posed the problem of finding a thermally stable uranium compound with a high vapor pressure at room temperature. Uranium hexafluoride (UF6) with a sublimation point of 56° C met these specifications. The isotopes are conveniently separated by submitting the UF5 vapor to a diffusion process. The UFg feed material for diffusion, in terms of fluorine chemistry, is pro- duced by a two-step process. Uranium dioxide is treated with anhydrous HF to form the so-called green salt, UF4. [1] U0 2 + 4 HF >■ UF 4 + 2 H 2 [2] UF 4 f F 2 - UF 5 The green salt is then fluorinated with fluorine gas to uranium hexafluoride. As enriched uranium metal is used as the reactor fuel, it is necessary to reduce the Tj235p 6 to the m etal. Part of the fluorine is recovered and returned as 70 percent aqueous hydrofluoric acid to the HF merchant for other purposes. Elemental Fluorine Although Moissan in 1886 succeeded in preparing fluorine as a free element by the electrolysis of potassium acid fluoride, it was not until World War II that the problem of large-scale production was solved. As pointed out, the develop- ment of an industrial fluorine cell was a necessity in the production of an atom bomb. Commercial fluorine cells still use potassium acid fluoride as an electro- lyte. However, by feeding HF to the cells to maintain the proper composition, continuous fluorine generation is achieved. A recently installed plant (8) has been reported to have a fluorine capacity of 364 pounds per hour with a possible expan- sion to 550 pounds per hour. Liquid fluorine is now available in tank truck tonnages, Besides its use in making UFg, liquid fluorine is being considered for use as an oxidizer in rocket engines. Rocket velocity and range are determined by the specific impulse or thrust of a fuel and oxidizer. Combined with existing fuels, liquid fluorine (5, 31) has the highest specific impulse of bipropellant systems. Because of its extreme reactivity, many problems will have to be solved and a long research road lies ahead. Very little fluorine is used for other purposes. Sulfur hexafluoride, pre- pared by direct combination of sulfur and fluorine, is an inert gas that is used as a dielectric in x-ray tubes. Higher metallic fluorides (CoF~, AgF 2 , MnF_, etc.) 32 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 and halogen fluorides (CIF3 and BrFj), useful in special fluorinations, are prepared only by oxidation with fluorine gas. An interesting application of chlorine trifluor- ide, CIF3, is in the perforation and cutting of pipe in oil wells below the earth's surface (4) . Other Inorganic Fluorides In addition to the fluorides discussed above, there are a number of other useful common compounds. The total production of these per year is estimated by Stuewe (29) to be about 14,500 tons. Most of the common inorganic fluorides are prepared by reacting aqueous hydrofluoric acid with the corresponding carbonates, oxides, or hydroxides . The bifluorides or acid fluorides are formed with an excess of acid. Anhydrous HF is used to prepare the water- sensitive fluorides such as boron trifluoride and others. Sodium fluoride is used in water fluoridation and in manufacture of rimmed steel, opaque glass, toothpaste, wood preservatives, and insecticides. About 6,000 tons appear to be the annual production. Some sodium fluoride is obtained also from silicofluorides. Only very small amounts of ammonium and potassium fluorides are used, the potassium salt being used in organic syntheses and sol- ders . The ammonium, potassium, and sodium bifluorides have many diverse uses. They all can be used in the frosting and etching of glass. Both the ammonium and sodium salts are used as laundry sours and iron stain removers. Sodium bifluoride is used in the acid treatment of steel prior to electrotinning for tin cans. The am- monium salt is utilized also in the treatment of oil wells, as an antiseptic and pre- servative, for the removal of scale in boilers and auto radiators, and in the extrac- tion of beryllium. Potassium fluoride is used in the production of fluorine gas and in solder compositions. Approximately 2,000 tons each of the ammonium and sodium salts are used annually whereas 300 tons is a close proximation for the potassium salt. Production of boron trifluoride (BF3) is estimated at 2,000 tons a year. It is available in cylinders or in combination with certain organic solvents, and is very corrosive in the presence of moisture. Its chief use is in the manufacture of coumarone-indene, petroleum resins, and lube oil additives, and as a catalyst in organic syntheses. Annual production of fluoboric acid (HBF4) and its fluoborate salts, generally prepared from boric acid or borax with hydrofluoric acid, is less than 1,000 tons. The acid is used in the cleaning and pickling of metals, electropolishing of alumin- um, and in organic syntheses. Because of high anode and cathode efficiency and a fine-grain deposit, the acid and certain salts are used in baths for specialty electroplating such as cadmium, chromium, copper, indium, iron, lead, lead-tin, nickel, silver, tin, and zinc. Ammonium fluoborate is added to the molds in mag- nesium casting to prevent oxidation. The sodium salt is used in the heat treatment of aluminum alloys to prevent blistering and crack formation and as a flux in non- ferrous metallurgy. The use of potassium fluoborate in the manufacture of brazing and soldering fluxes and in grinding wheels has been reported. Silicon tetrafluoride (SiF4) gas has been useful in sealing off downhole water zones during air and gas drilling (30). The dry gas upon injection into a well penetrates into the permeable water zone where it hydrolyzes to a fluosilicic acid gel thus plugging the pore passages. Atomic and rocket age demands for new materials have stimulated fluorine chemical producers to offer many fluorides, some of which were considered Ivory ILLINOIS FLUORSPAR 33 Tower rarities 20 years ago. Sales advertisements have been noted on the fluorides of antimony, barium, bismuth, cadmium, caesium, chromium, cobalt, copper, iron, lead, lithium, magnesium, manganese, mercury, molybdenum, nickel, rare earth fluorides, rubidium, selenium, silver, strontium, tin, titanium, tellurium, tungsten, zinc, zirconium, and many double fluorides of chromium, iron, tantalum, titanium, zinc, and zirconium in the form of ammonium, potassium, and sodium complexes. Fluosilicic Acid and Salts No discussion on the uses of fluorine compounds is complete without men- tion of fluosilicic acid and its salts called fluosilicates or silicofluorides . They can be prepared from low-grade fluorspar and sulfuric acid. However, they are available at low cost as a by-product from domestic fertilizer phosphate rock acid- ulation and through tonnage importation from Europe and Japan. Under these cir- cumstances it is not economically feasible to produce them from fluorspar. Fluosilicic acid (I^SiFg) is used in water fluoridation, electroplating, as a concrete hardener, disinfectant, wood preservative, and in the manufacture of metallic fluosilicates and fluorides. The production of sodium fluosilicate (Na2 SiF fi ) in 1955 was 18, 000 tons, almost three times as much as the rest of the salts combined. Approximately 40 percent of the sodium salt is used in water fluorida- tion, the remainder being used as a laundry sour, in enamel and opal glass, insec- ticides, and foam rubber. The potassium salt (K2SiF5) is used in enamels, light metal fluxes, and synthetic mica. Zinc fluosilicate is used as a wood preservative, and like the magnesium salt, is used also as a laundry sour and concrete hardener. The chief uses for ammonium fluosilicate are in water fluoridation, mothproofing, and as a laundry sour. Used as insecticides and in ceramics as opacifying agents are the barium and calcium salts. Lead fluosilicate appears in electrolytic lead refining and plating. Occasionally salts of aluminum, iron, nickel, and silver are mentioned with special uses. DIRECTORY OF ILLINOIS FLUORSPAR MINES AND MILLS The Illinois fluorspar mining industry comprises mines operated in connec- tion with processing mills, mines operating more or less continuously but having no mills, and small mines worked periodically. Below are listed those companies with mills and companies without mills that mined more than 3,000 tons of ore in 1957. Companies with Mills Aluminum Company of America, Rosiclare: Mill: 400-ton flotation-heavy media mill, Rosiclare Mine: Fairview-Blue Diggings Mine, Rosiclare Minerva Oil Company, Fluorspar Division, Eldorado: Mills: 325-ton flotation mill, Mine No. 1, Cave in Rock 750-ton flotation-heavy media mill, Crystal Mine, Route 1, Elizabethtown Mines: Mine No. 1, Cave in Rock Crystal and Victory Mines, Route 1, Elizabethtown Jefferson Mine, Route 4, Golconda Rose Creek Mine, near Herod 34 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 Ozark-Mahoning Company, Mining Division, Rosiclare: Mill: 500-ton flotation mill, Rosiclare Mines: Deardorff, W. L. Davis No. 2, North Green, East Green, Hill-Ledford, Oxford, and Shafts No. 2, No. 3, No. 5, No. 11, and No. 16, all near Cave in Rock Rosiclare Lead and Fluorspar Mining Company, Rosiclare: Mill: 300-ton flotation-heavy media mill Mine: Rosiclare Mine (idle) Mackey-Humm Fluorspar Mining Company, Box 336, Golconda: Mill: 100-ton heavy media mill Mine: Mackey-Humm Mine, Humm's Wye (idle) Companies without Mills Egyptian Mining Company, Rosiclare: Empire Mine, near Eichorn. Goose Creek Fluorspar Mining Company, Cave in Rock: Goose Creek Mine, near Sparks Hill. Hicks Creek Fluorspar Mining Company, Elizabethtown: Douglas Mine, near Eichorn. Hoeb Mining Company, Cave in Rock: Hoeb Mine, near Sparks Hill. J. W. Patton and Sons, Elizabethtown: Crabb Mine, near Eichorn. Redd Mining Company, Route 4, Golconda: Hamp Mine, near Hicks. Ridge Mining Company: Ridge Mine, near Karbers Ridge. REFERENCES 1. Bogue, R. H., 1955, The chemistry of Portland cement, 2nded.: p. 217-218, Reinhold Pub. 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Einecke, G., 1956, Die Flussspatlagerstatten der Welt: p. 385, Verlag Stahleisen M. B. H., Dusseldorf. 14. Hatmaker, Paul, and Davis, Hubert W., 1938, The fluorspar industry of the United States with special reference to the Illinois-Kentucky district: Illinois Geol. Survey Bull. 59, p. 16. 15. Henry, J. L., and Lafky, W. M . , 1956, Aluminum reduction systems: Ind. Eng. Chem., v. 48, Jan., p. 126-128. 16. Hoover, H. C. and L. H., 1950, G. Agricola, De Re Metallica: Dover Pub., Inc., New York. 17. Johnstone, S. J., 1946, Minerals for chemical and allied industries: Ind. Chemist (London), v. 22, Dec, p. 757-758. 18. Kastens, M . L., and McBurney, W. G., 1951, Calcium cyanamide: Ind. Eng. Chem., v. 43, May, p. 1020-1033. 19. Kirk, R. E.,and Othmer, D. F., 1951, Encyclopedia of chemical technology: v. 6, p. 703, Interscience Encyclopedia, Inc., New York. 20. Lovelace, A. M., Postelnek, W., and Rausch, D. A., 1958, Aliphatic fluor- ine compounds: p. 45, Reinhold Pub. Corp., New York. 21. Machin, J. S. and Vanacek, J. F., 1940, Effect of fluorspar on silicate melts with special reference to mineral wool: Illinois Geol. Survey Rept. Inv. 68. 22. Maier, F. J., and Bellack, E., 1957, Fluorspar for fluoridation: Jour. Am. Water Works Assoc, v. 49, no. 1, p. 34-40. 23. McDougal, R. B.,and Foley, J. M., 1960, Fluorspar in the fourth quarter 1959 and summary of the year: U. S. Bur. Mines QFR 101. 24. Pearson, T. G., 1955, The chemical background of the aluminum industry: Roy. Inst. Chem., Lecturers, Monographs and Reports, No. 3, London. 25. Philbrook, W. O., and Bever, M. B., 1951, Basic open hearth steel making: 2nd ed., Am. Inst. Mining Met. Engrs., New York. 26. Portland Cement Assoc, 1957, Fluxes or mineralizers for Portland cement clinker: Special bibliography No. 56, Portland Cement Assoc. , Chicago. 27. Simons, J. H., 1950, Fluorine Chemistry: v. 1, p. 553-574, Academic Press Inc . , New York . 28. Stockbarger, D. C, 1949, The production of large artificial fluorite crystals: Discussions Faraday Soc (London), no. 5, p. 294-299. 29. Stuewe, A. H., 1958, Hydrogen fluoride: Chem. Eng. News, v. 36, no. 51, p. 34-38, 57. 36 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 296 30. Sufall, C. K., and McGhee, E., 1959, Water shut-off treatment for air and gas drilling: Oil and Gas Jour. , v. 57, no. 50, p. 123-127. 31. Thompson, R. J., Jr., 1958, Rocket propellants: Chem. Eng. News, v. 36, no. 25, p. 62. 32. U. S. Bur. Mines, 1956, Mineral facts and problems: U. S. Bur. Mines Bull. 556, p. 285. 33. U.S. Bur. Mines, 1960, Minerals yearbook for 1958: U.S. Bur. Mines. 34. U. S. Geol. Survey, 1956, Fluorspar reserves of the United States estimated: Press Release (Nov. 23), Office of Minerals Mobilization and the U.S. Geol. Survey, U.S. Dept. Interior Information Service. 35. Weller, J. M., Grogan, R. M. and Tippie, F. E., 1952, Geology of the fluor- spar deposits of Illinois: Illinois Geol. Survey Bull. 76. Illinois State Geological Survey Circular 296 36 p., 6 figs., 1 pi., 4 tables, 1960 nncnni CIRCULAR 296 ILLINOIS STATE GEOLOGICAL SURVEY URBANA *S>-