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Uranium was the prima donna of 1978, and the exploration pace was fast and furious in traditional uranium producing areas such as the Powder River Basin, Grants mineral belt, San Juan Basin, and Uravan mineral belt. Adding fuel to the fire were several significant discoveries: The Date Creek Basin of western Arizona, the McDermitt caldera of northern Nevada, and Tallahassee Creek in Colorado's intermontane basin. Advances in solution mining haw resulted in deeper drilling on the Texas Coastal Plain, and the price of uranium has encouraged widespread exploration in frontier areas and non-sandstone environments.

Jan 5, 1979

By C. DeWitt Smith

"It just looks like everything is doing fine but humans," wrote Will Rogers fifty years ago. "Animals are having a great year, grass was never higher, flowers were never more in bloom, trees are throwing out an abundance of shade for us to loaf under. Everything the Lord has a hand in is going great, but the minute you notice anything that is in any way under the supervision of man, why, it's cockeyed." Do these words from two generations ago apply to oil shale? The United States has been blessed with deposits that can yield synthetic crude oil at a cost competitive with natural crude oil-under present economic conditions and with existing technology. Yet, the oil shale program is cockeyed because of the artificial obstacles that have been placed in its path "under the supervision of man." But more about this later. For the moment, let's focus on...

Jan 10, 1974

By P. W. George

This paper presents geological data regarding deposits of over 7,500,000 tons of fine-grained sulphide ore in barite gangue. A series of pyroclastics and arkoses was intruded by sills of quartz porphyry in connection with batholithic intrusions of granite 3 miles from Buchans. Gentle folding, with fracturing and shearing of tuff beds and intruded quartz porphyry, accompanied and followed the intrusion of granite and porphyry. The sulphide-barite mineralization is localized primarily in fractured and sheared tuff beds, but also in the sheared quartz porphyry. Two structures have proved particularly favorable for mineralization-one, the center of an anticline; the other, a series of weak, incompetent tuff beds intruded by thin sills of quartz porphyry and located between strong beds of arkose. During the folding the weak tuff with intruded quartz porphyry was intensely sheared and contorted and subsequently mineralized by sulphides and barite. INTRODUCTION Buchans is 5 miles north of Red Indian Lake, in Central Newfound- land, at an elevation of 900 ft. above sea level and 400 ft. above Red Indian Lake, and is reached by a 37-mile private railway from Miller- town Junction. The first ore body found at Buchans was discovered some 30 years ago in the bed of Buchans River, by Matty Mitchell, an Indian woodsman employed by the Anglo-Newfoundland Development Co. Ltd. In the years following the discovery the ore was developed by shaft-sinking and drifting, with results indicating a lenticular ore body in a shear zone, containing about 100,000 tons of extremely fine-grained sulphide ore in barite gangue averaging about 0.05 oz. Au, 4 oz. Ag, 1.5 per cent Ch, 10 per cent Pb, 18 per cent Zn. Because a profitable metallurgical treatment for the ore was not found, the mine was closed down in 1911. In 1915, Mr. H. A. Guess, Vice President of the American Smelting & Refining Co., learned of the Buchans River ore body, and after metallurgical tests had been carried on from time to time in his company's testing plant a satisfactory separation of the sulphides by selective flotation was finally effected in 1925. Prospecting for additional ore bodies was begun in 1926, utilizing geophysical methods under the direction of Hans Lund-

Jan 1, 1937

By B. L. Averbach, M. Cohen

THE PROBLEM MANY hardened steels contain significant quantities of retained austenite even in cases where the carbon and alloy contents are low. In fact austenite has been detected in plain carbon steels containing as little as 0.50 pct carbon.1 Although the austenite may not be visible metallographically it causes definite dilatometric and magnetic effects during subsequent tempering or subatmospheric cooling.1,2,3 Therefore if the reactions which hardened steels undergo during later treatment are to be understood in quantitative fashion it is most essential to have some kind of absolute analysis for the austenite content in hardened steels. Once this analysis has been made, the austenite transformations can be followed precisely by observing such sensitive phenomena as changes in length or in magnetization but the latter techniques can only determine differences in the amount of retained austenite and usually an independent method must be found to put these differences on an absolute basis. In certain instances the microscope can be used advantageously to determine the percentage of retained austenite. The quenched sample is tempered to "darken" the martensite with minimum decomposition of the coexisting austenite, and then is polished and etched in the usual fashion. If the austenite is clearly distinguishable from the tempered martensite and other possible constituents its volume percentage can be measured quantitatively by point counting or lineal analysis.4 Such microscopic methods, however, depend on the etch being sufficiently discriminatory. In fairly coarse structures, if the austenite content is greater than 10-15 pct, there is probably little smearing of the etch, and point counting or lineal analysis seems to be quite accurate. On the other hand if the structure is difficult to resolve, as in commercially treated fine-grained steels which contain less than 10-15 pct retained austenite, the latter may be completely obliterated by the dark etching martensite or it may appear disproportionately low as the interfaces between the two constituents become difficult to distinguish. Another disadvantage of the metallographic method is the need for "darkening" the martensite and hence the determination cannot be applied to as-hardened steels. The required tempering may spoil the structure for other tests or may even remove a small part of the austenite which is being sought. X ray methods hold more promise for covering the range under 15 pct retained austenite. Although austenite and martensite in the hardened steel may be chemically identical, their crystal structures and lattice parameters differ, and the intensity of an austenite diffraction line is some continuous function of the percentage of re-

Jan 1, 1948

By J. N. Anderson

Developments in reverberatory furnace practice at Noranda over the period 1928 to 1953 are described. Features of interest are increasing furnace tonnage from 700 to 2000 tons per furnace day, the use of the suspended basic roof, and improvements in furnace fuel ratio. Points of comparison and contrast between Canadian and American furnace practice are given. OPERATIONS at the Noranda smelter have been described in a series of papers published between 1930 and 1945.1-4 In the present paper the development of reverberatory furnace practice over the 25 year period from the beginning of operations up to the present time will be reviewed and current furnace practice will be described in some detail. Particular attention will be given to those features which are characteristic of Canadian practice: first, the use of the suspended basic roof; second, the deliberate driving of furnaces to give tonnages in the range of 1400 to 2000 tons of solid charge per furnace day; and third, the continuous operation of furnaces at high tonnage for many years without any extended shutdown for repairs or rebuilding. Finally, points of comparison and contrast between reverberatory furnace practice in Canada and the United States will be discussed. The Noranda smelter, which started in December 1927, was built for the reduction of ore from the Horne mine where early development had shown a comparatively small tonnage of rich cop-per-gold ore of a grade and character which would require direct smelting. The smelter was designed for a capacity of 1000 tons of ore a day and originally consisted of eight roasters, two reverberatory furnaces, and two converters, together with necessary auxiliaries. The discovery of a large new body of ore in 1928 made it necessary to increase both the size and the scope of the reduction plant. A mill which was ultimately brought to a capacity of 3000 tons a day was built for concentrating low grade ore and in addition the capacity of the smelting plant had to be greatly expanded, so that for the next fifteen years every effort in the smelter was directed toward achieving maximum tonnage. Because the layout and design of the smelter made it impracticable to add a third furnace, it was necessary to increase the tonnage on the two original furnaces by improvements in furnace design and operation, roasting and converting equipment being added as required to meet the demands of increased furnace capacity. The smelter tonnage, which reached a peak in 1941, was curtailed in 1944 when it became necessary to operate on a one-furnace basis because of a reduction in the output of the Horne mine due to a shortage of labor. Two-furnace operation at a moderate tonnage was resumed in 1949. In the early years the smelter tonnage was made up almost entirely of Noranda ores and concentrates. However, since 1937 an increasing tonnage of ores and concentrates from other mines has been treated in the smelter. In recent years, with decreased production from the Horne mine, copper concentrates from several mines in the district, treated on a custom basis, have formed an important part of the smelter tonnage. A review of developments in reverberatory furnace practice at Noranda falls naturally into the following four periods: 1—1928 to 1935, the early years; 2—1935 to 1944, the period of greatest change and development; 3—1944 to 1949, one-furnace op-

Jan 1, 1955

By C. E. Johnston

In December 1956, International Minerals & Chemical Corp. installed a rope-suspended belt haulage system in its Carlsbad, N. M., potash mine to complement the already existing rail transport arrangement. In this article the author describes when and where each system is used, the advantages and disadvantages of both, and future planning and proposed changes in haulage at IMC. The haulage system at the International Minerals & Chemical Corporation (IMC) potash mine near Carlsbad, N. M., reached a turning point in December 1956 with the introduction of rope-suspended belt haulage. In fact, IMC pioneered the use of this type of belt in the potash industry. Since that time belt conveyance has been employed as an extension of the rail system but not as a replacement of the main rail haulage. IMC's potash mine is located in the Permian Basin, approximately 20 miles east of Carlsbad in Eddy County, N. M. The 800, 850 and 900-ft levels have been exploited. From these levels over 60 million tons have been extracted. The two ore minerals are sylvite (KCl) and langbeinite (K2SO4. 2MgSO4). The principal gangue mineral is halite, with minor amounts of polyhalite, kainite and leonite. Langbeinite is mined on the 850-ft level and sylvite on the 900. The 800-ft level, with both langbeinite and sylvite mineralization, is idle. Mining heights vary from 54 in. to over 10 ft. A room and pillar mining system is used. Geologically, mining is done in the Salado salt formation. The U.S. Geological Survey has classified the 900-ft sylvite level as the first ore zone and the 850-ft langbeinite level as the fourth ore zone. Since the grade of sylvite is low, mineralization at the IMC mine is somewhat irregular and salt horses, are common. Selective mining and a flexible haulage

Jan 1, 1963

By H. P. Greenwald, H. C. Howarth

The rapidly increasing use in coal mines of portable auxiliary fans, which are generally 'blowers" employed in connection with canvas tubing, raises questions concerning the hazards of such equipment, especially where the practices are opposed to established methods of ventilating face workings. Half a dozen or more coal-mine explosions and some fires have been attributed to the use of auxiliary fans; moreover, competent mining engineers have found many dangerous installations and methods of use-for example, intermittent running of the fans in gassy mines with consequent accumulations of firedamp at the faces. These facts have led the U. S. Bureau of Mines to issue this recommendation: "In the interest of safety, the Bureau of Mines, Department of Commerce, recommends that auxiliary fans or blowers should not be used in coal mines as a substitute for methods of regular and continuous coursing of the air to every face in the mine." The comparatively recent introduction of new types of mining machines, mechanical loaders, face conveyors, and slabbing machines has encouraged the trial of new systems of face mining, all of which have for their object the rapid advance of the faces. Although the latter has certain economic advantages, in gassy mines the rate at which gas is given off is generally found to increase in proportion to the speed of advance into new territory, which in turn increases the difficulties of efficient ventilation of the face workings. Some of the systems of advance mining being tried in connection with new mechanizing methods practically compel the use of blower fans and tubing, as single narrow places arc now driven 300 ft. or more without crosscuts. In some instances a series of parallel headings are driven without crosscuts pre-

Jan 1, 1928

By Ralph Smith

DEVELOPMENT of the lime industry in Ste, Genevieve County began in a crude way in 1840. According to information furnished by the Missouri Bureau of Geology, in the early days small vertical kilns built of stone were used, and wood was the fuel. Modern development began in 1904 when one company introduced steel shells lined with firebrick. Within a few years two more companies erected similar plants, and in 1925 a fourth company began operations. Thus there are today four lime companies at Ste. Genevieve, all operating at high capacity and with a gradually increasing production. GEOLOGY The limestone of Ste. Genevieve County, which has the chemical composition and purity required for lime burning, is the upper 80 or 90 ft. of Spergen formation. The Missouri Bureau of Geology, in its geological map of Ste. Genevieve County, gives the Spergen formation a total thickness of 160 ft., but only the upper portion is pure enough for lime burning, with an average raw-stone analysis of 98.7 per cent CaCO3; 0,35 Si02; 0,3 R203; 0.35 MgCO3; 0.3 SO3. The Spergen, one member of the Meramac group, Iowa series, of the Mississippian system, underlies an area approximately 12 miles long north and south, by 5 miles wide east and west (Fig. 1) in Ste. Genevieve County. The entire eastern two-thirds of Ste. Genevieve County is sedimentary, the formations dipping gently toward the east on an average grade of about 4 per cent, or 2 ½ °. Thus the outcrops of the various sedimentaries run approxi-mately north and south. A line running west from Ste. Genevieve crosses the outcrops of the sedimentaries, ranging from the top of the Mississippian to the Ozarkian geological system in a space of 12 miles. Thus with the gentle dip of 2 1/2° the 160-ft. thickness of the Spergen formation stretches out in its outcrop so that it is approximately one mile

Jan 1, 1938

By S. J. Hruska, G. M. Pound

The critical supersaturations for appreciable nucleation rate of cadmium crystals on copper and glass substrates at 186°Kwere measured as a junction of thermal-beam energy over a range of source temperatures between 616" and 839OK. There was no effect of source temperature on critical super saturation. This implies that the adsmbate prior to nucleation is in thermal equilibrium with the substrate. THE deposition of metallic vapors on solid substrates has been found to exhibit a critical behavior in that the rate of formation of deposit increases markedly when the intensity of the vapor source is increased slightly.* Evidence of the ability of sub- where Je is the flux which would arrive if the substrate were equilibrated with bulk condensate at the adsorbate temperature. The following work was undertaken to test this hypothesis. A) Energy Exchange Between Metallic Vapor and Substrates. When a freely translating atom collides with a stationary solid body its energy and momentum undergo changes which determine whether the atom is reflected or adsorbed. An atom is considered to be reflected if it returns to a freely translating state after remaining under the influence of the body for only a time comparable to the period of oscillation of atoms on the surface. An atom which remains for a longer time is said to be in an adsorbed state. The parameter which describes the energy transfer occurring at the interface is the thermal-accommodation coefficient which may be defined in terms of energy as Ei = average energy of impingent atoms, Eeq = average energy of an emergent atom which has equilibrated with the substrate, and Eem = average energy of an emergent atom. If a temperature is assigned to each of these energies, we have at as defined by Knudsen.2 Since this allows no distinction between reflected and evaporated atoms, a more specific definition is introduced for the present purposes, namely 71 = probability that an impingent atom is transferred to an adsorbed state, aj = thermal-accommodation coefficient for reflected atoms, and aTc = thermal-accommodation coefficient for adsorbed atoms. During a time t,, the mean stay time, prior to evaporation the adsorbed atom (adatom) will interact with the substrate and this will have the net effect of transferring the adatom towards a state of

Jan 1, 1964

By P. H. Dudley

THE piping and segregation of ingots of steel is a comprehensive subject, and must be studied in reference to the different grades of soft, medium, and hard steel, rather than to discuss it in a general manner, as though applicable to all grades. Rail steel, however, will receive the most consideration in this paper, for the wheel-loads of the motive pourer and rolling stock have doubled from 1890 to 1910. Steel rails and tires which were efficient under the light loads, became less serviceable under the double wheel-loads, quadrupled tonnage, and higher speeds. Bessemer Steel. Bessemer steel of froth 0.10 to 0.15 per cent. of carbon, for splice-bars, spikes, and tie-plates, rises in setting, and is cast in bottle-mouthed molds, which must be capped to prevent an over-flow from the top. This grade of steel rises in the molds and makes a longer ingot than the volume of molten steel when first teemed. The ingots which are allowed to cool and then cut open, show, particularly in the upper part, large occluded blow-holes, and when they are Dot oxidized or do not contain foreign matter, weld more or less completely when the steel is rolled or forged above 1,100° C., and it :is in this way that the blow-holes are closed it the low-carbon steels.

Jan 4, 1913

By L. G. Huntley

In view of the recent advance made in the knowledge of the nature and conditions accompanying the occurrence of oil and gas, and of the recent activity in drilling in Wyoming, Montana, and western Canada, a discussion of the probabilities of obtaining production in such a reservoir as the Dakota sand in general, and in particular districts, is thought by the author to be timely and likely to result in more intelligent operating in certain parts of the territory underlain by this sand. In Canada particularly it is thought that these general considerations have equal if not more significance in a consideration of the oil and gas possibilities of the formations than have the various local conditions. Age and Nature of Deposition of the Dakota Sand The Dakota is distinctive in that it is known to form a generally continuous sheet of sand underlying the greater part of Alberta, Saskatchewan, Manitoba, North and South Dakota, Montana, and large areas in Nebraska, Colorado, and Wyoming. It does not seem to have been laid down in more or less isolated lenses, as has been the case with most oil-sand horizons. Except in northern Alberta, the Dakota sand contains fresh-water fauna, having been deposited very uniformly over these wide areas in shallow water with prevailing strong currents. In northern Alberta marine and brackish water conditions prevailed. In this district it forms the basal member of the Cretaceous sediments, directly overlying beds of Devonian limestone along a great unconformity in the Athabasca River valley and eastward. In southern and western Alberta it is underlain unconformably by the Kootenay shales (Lower Cretaceous), and by Jurassic and Carboniferous rocks. In the United States in South Dakota it was in places deposited upon Cambrian quartzites, and in other places directly upon the granite. In the State of Dakota, and in the

Jan 1, 1916

By Gealy W. Wallwork

INTRODUCTION The administrative processes of coal mines are becoming increasingly complex. As society evolves into a more complicated structure with greater emphasis on individuality, government regulations reach deeply into every activity in an effort to force individuals into a standardized mold. These contradictory pressures add an extra burden to the administration of a mining operation. Recent years have brought a substantial change in the skills needed by mine supervisors and managers. As a result, a better understanding of the administrative functions is necessary. The mine superintendent has the overall responsibility for the mine; for effective operation he must be sufficiently knowledgeable to oversee all the complex functions that make up the mine. This chapter does not cover all the administrative requirements because of the variation in mine operation and in company policies and organizational structure. It does attempt to identify the administrative functions that would be required at a large mine with a preparation plant. It is assumed that the mine operation is decentralized with very little duplication of functions at the organizational levels above the mine. Thus each function is assumed to be relatively complete at the mine and under the general supervision of the mine superintendent. EMPLOYMENT PROCEDURES Throughout the mining industry, in deep or surface mining, in union or nonunion companies, the success or failure of an organization is directly related to the caliber of employees who make up the organization. A company is nothing more than a group of people working together with

Jan 1, 1981

By J. W. Gwinn

The underground haulage system in the lead-silver mine of the Bunker Hill & Sullivan Co., situated at Kellogg, Idaho, is the most extensive in the Cæur d'Alene district, comprising about 35,000 ft. of tunnels, drifts, and cross-cuts where locomotive haulage is in use. The main working adit, known as the Kellogg tunnel, or No. 9 level, is approximately 10,000 ft. in length from the portal to the main working shaft and extends beyond that about 4,500 ft. in each of two directions. On this level all the ore from the Bunker Hill & Sullivan, the Sierra Nevada Consolidated, and the Caledonia Mining Co.—an average of 44,600 tons per month—is hauled to the mills, located a short distance from the portal. Electric haulage by the trolley-type locomotive is used on this level throughout. Below this level, at intervals of 200 ft. vertically, are five other working levels (Nos. 10, 11,12,13, and 14); and the total haulage distance on these, where electric locomotives are used, is approximately 16,000 ft. No. 13 level has but recently been opened up and is not working to capacity; while the main cross-cut on No. 14 has just been started, and has no need of power haulage. Of the four levels equipped with electric haulage, Nos. 11, 12, and 13 have storage-battery locomotives, and No. 10 still retains the trolley type by reason of the small and decreasing tonnage produced. Electrification - Electric power is supplied to the mine by two systems. The first, the 500-volt direct-current trolley, was installed in 1897 when the Kellogg tunnel was started, and was extended as the tunnel advanced, being used for the first trainload of ore on Nov. 17, 1902, since which time it has been in continuous service. The current for the line is transmitted on a No. 00 copper wire as far as the shaft, and on No. 0 wire throughout the remaining length of the Kellogg tunnel; and until the installation of the storage-battery locomotives it was used in practically all the cross-cuts and drifts on each level below No. 9.

Jan 1, 1915

By Harrison Everett Ashley

(Pittsburg Meeting, March, 1910.) Slimes are usually defined as all material passing a certain-sized sieve, which is invariably the finest sieve employed by each metallurgist in his tests; 100-mesh and 200-mesh have been taken as the limits by different writers in recent volumes of the Transactions ; 150-mesh is common practice. The reader of the first two volumes of Richards 1 is impressed by the inflexibility with which all grinding-arrangements are praised or condemned according as they make little or much slime. Until recently, one of the principal aims of the mill-man was to keep down the slimes. He was obliged to have separate apparatus for sand- and slime-treatment. The latter was sometimes puzzling and erratic. Often it was found most .economical to omit treatment of the slimes entirely, or to store them in immense basins or heaps, waiting for possible future improvements in methods of treatment. Recently, improved processes of agitation and filtration have made possible the successful extraction of values from many slimes. The tendency, when the metal is exceedingly finely disseminated, is to cut out all sand-treatment and to slime everything. These processes have been almost entirely mechanical in their conception, and it is the object of the present paper to show that certain chemical considerations may greatly hinder or assist their successful operation. It has long been a source of dissatisfaction to chemists that their analyses fail to be of much help to the clay-worker; that it is a matter of common occurrence for clays of closely identical ultimate chemical constitution to show the widest possible divergence in physical properties. * Published by permission of the Director of the U. S. Geological Survey. Ore Dressing (1903).

Aug 1, 1910

By W. G. Matteson

The origin of the salt domes of the Gulf coastal plain has been investigated by many of the most able geologists, but the problem cannot be said to have been satisfactorily solved. Since 1860, numerous theories have been presented, only to be discarded, at least in part, as more complete infomation revealed their fundamental weakness. Real progress toward solution dates from 1902, when Hill1 advanced the theory of secondary deposition of the domal materials from saturated solutions of hot saline waters ascending from great depths under hydrostatic head along structural lines of weakness. Shortly thereafter, Harris,² using Hill's hypothesis as a basis, explained the doming and pronounced uplift associated with these salt cores as the result of forces exerted by growing salt crystals. This was a marked advance over the ideas of Coste3 and Hager,4 since no evidence of igneous intrusives, as they assumed to explain the uplifts, had been found associated with the domes. Harris5 developed his theory until it offered such apparently plausible explanations of so many details of dome phenomena that his hypothesis and conclusions received widespread acceptance, despite some serious objections, and today his theory, somewhat modified, is considered by many able investigators to be the best explanation of the origin of these domes. The immense production of oil per acre, the recognition of the high lubricating quality of the oil, the development and recognition of the efficiency and advantages of oil-burning vessels, with the subsequent exceptional demand for fuel oil, and the resultant advance in the price of coastal crude, have been responsible for a prospecting and develop- 1 Robert T. Hill: Beaumont Oil Field with Notes on Other Oil Fields of the Texas Region. Jnl. Franklin Inst. (1902) 164, 143. 2Gilbert D. Harris: Rock Salt in Louisiana. Louisiana Geol. Survey Bull. 7 (1907) 76. ³E. Coste: Volcanic Origin of Natural Gas and Petroleum. Jnl. Canadian Min. Inst. (1903) 6, 73. 4Lee Hager: Mounds of the Southern Oil Fields. Eng. & Min. Jnl. (July 28, 1904) 78,137, 180. 6Gilbert D. Harris: Geologicel Occurrence of Rock Salt in Louisiana and East Texas. Econ. Geol. (1909) 4, 12.

Jan 1, 1921

By Harold W. Aldrich, Walter G. Scott

The leaching process of the Inspiration Consolidated Copper Co. is based upon the solubility of oxidized copper in sulfuric acid and the solubility of sulfide copper, largely in the form of chalcocite, in ferric sulfate solution. This necessitates the carrying of a rather large amount of iron in solution. The ferric sulfate is regenerated from ferrous sulfate by the oxygen given off at the anode during electrolytic precipitation of the copper. In September, 1924, excavation was started at Inspiration, Arizona, for the construction of a plant to treat 7500 tons of ore per day. When the plant was begun, the fact developed that by a minor change in the height of the overflow on the leaching tanks, 9000 tons could be charged into each tank and treated satisfactorily. This determined the maximum capacity of the plant as 9000 tons per day. The first ore was charged in October, 1926, and there are now available the records of five complete years of operation; namely, 1927 to 1931, inclusive. The original estimate of copper content of the ore to be mined for this plant was 1.19 per cent, of which 0.77 per cent was as oxide and 0.42 per cent as sulfide. From the metallurgical results obtained at the 35-ton pilot plant, it was estimated that a 90.0 per cent extraction of the oxide copper and a 75.0 per cent extraction of the sulfide copper could be made. It was estimated that the tailing would carry 0.182 per cent total copper, resulting in a

Jan 1, 1934

By W. C. Phalen

Introduction............................... 100 Production and Exportation of Phosphate Rock.............. 101 Methods of Conservation........................ 101 Introductory Note........................ 101 Mechanical Methods of Conservation............... 103 Grades of Brown Phosphate Rock............... 106 Preparation of Phosphate Rock for Market, with Phases of Conservation Involved..................... 106 Removal of Overburden.................... 106 Methods of Mining...................... 107 Reworking Deposits..................• 107 Working "Cutters"................... 109 Washing and Drying..................... 111 Conservation of Fines .................... 113 Chemical Methods of Conserving Phosphate Rook.......... 113 Application in the West.................... 113 Chemistry of Process.................... 114 Substitutes for Phosphate Rock..................... 115 Natural Substitutes........................ 115 Phosphatic Limestone..................... 115 Apatite, Nelsonite and Other Minerals Containing Phosphate ... 116 . Apatite in Virginia................... 117 Guano........................... 118 Greensand (Marls)...................... 118 New Jersey....................... 118 Kentucky........................ 119 . Tennessee........................ 120 Alabama........................ 120 Excrement.......................... 120 Bones............................ 121 Artificial Substitutes....................... 121 Basic Slag......................... 121 Phosphate Rock Reserves....................... 122 Florida............... 122 .

Jan 1, 1918

By L. H. Dushak

DURING the war period of quicksilver activity there were a number of departures from what may be termed the classical quicksilver metallurgy. Attempts were made to beneficiate low-grade ores by gravity concentration and flotation; mechanical furnaces began to replace the Scott furnace and the vertical coarse-ore furnaces, and condensers of sewer tile and redwood tanks were used in place of the older brick and stone condensing chambers. Other developments that have occurred during the current period of quicksilver activity are mainly in the nature of improvement and further refinement of those started during the war period. Each period of quicksilver activity has been accompanied by the proposal of various new processes, including wet methods for the treatment of quicksilver ores and innovations in furnaces, retorts and condenser equipment. As far as the author knows, nothing of economic significance in the way of "new processes" has been developed. There is in fact no real need for any essentially new process for the treatment of quicksilver ores; the direct furnace treatment is simple and inexpensive. Moreover, with rare exceptions, the quicksilver industry has no complex or refractory ore problems corresponding to those which are receiving more and more attention from metallurgists in other branches of the nonferrous field. Under these conditions improvements in quicksilver metallurgy must be looked for through the adaptation of current developments in engineering and metallurgy generally to the particular needs of quicksilver practice rather than through the invention of new processes.

Jan 1, 1930

By K. A. Jackson, J. D. Hunt

A new classification of eutectics is proposed, based on tlze entvopies of wzelting of the tuio eutectic phases. The clnssification was used to predict suitable tvansparent analogs of the metallic systems. Experimental confir?nation loas obtained for the theovetical shape of the lamellar solid-liquid interface, fov the fault mechanisms of lanzellar spacing changes, and for the development of low-energy solid-solid boundaries between the lamellae. An explanation is presented to account jov the irvegular and coinplex regular structures zrhich are found in some eritectic systems. FrOM experimental observations, single-phase materials can be divided into two groups according to their solidification characteristics, those that grow as faceted crystals and those that do not. acksonl' showed from thermodynamic reasoning that the type of growth depended on a factor a which was almost thg entropy of melting. Most nonmetals have high entropies of melting (a greater than 2) and grow with crystalline facets. Most metals have low entropies of melting (CY less than 2) and grow almost isotropically with no facets. The authors propose that eutectics may be classified in a similar manner. There are three groups of eutectics, those in which both phases have low entropies of melting, those in which one phase has a high and the other phase has a low entropy of melting, and those in which both phases have high entropies of melting. Lamellar or rodlike structures are formed in systems in which both phases have low entropies of melting. In these alloys dendrites of either phase may be formed, when the alloy is rich in the relevant component. Examples are Pb-Sn, Sn-Cd, Pb-Cd, Sn-Zn, Al-Zn. Irregular, Fig. 14((), or complex regular, Fig. 14(b), structures are formed in alloys in which one phase has a high entropy of melting and the other has a low entropy of melting. Examples are A1-Si, Zn-MgzZnll, Pb-Bi, Sn-Bi. When the alloys are rich in the low entropy of melting phase, dendrites are formed; when the alloys are rich in the high entropy of melting phase, faceted primary crystals are produced. These crystals are sometimes called hoppers or pseudodendrites. In this work the term dendrite will only be used to describe nonfaceted primary crystals. Dendrites are not formed during solidification in high entropy of melting single-phase materials. The third group of eutectics includes alloys in which both phases have high entropies of melting. Each phase grows with a faceted solid-liquid interface. Since most metals do not have high entropies of melting, metallic examples in this eutectic group are rare. However they may occur between some intermetallics and semiconductors or semimetals such as silicon, germanium, and bismuth. Attempts have been made to study eutectic solidification visually by watching the growth process.374 Since metals are not transparent, the observations had to be made on external surfaces. This difficulty can be overcome by using transparent analogs of the metallic systems. As was mentioned earlier, most single-phase compounds have entropies of melting greater than 2 and so grow as faceted crystals. Recently organic materials with entropies of melting less than 2 were investigated.' These materials grow in exactly the same way as the low entropy of melting metals. When the materials are pure, they grow with a solid-liquid interface parallel to an isotherm; when they are impure, cells or dendrites are formed. Since these materials are transparent, have low melting points, and even have cubic structures, they should be ideal for making up transparent analogs of the metallic eutectics. The purpose of the present work was to investigate these organic eutectics and to see whether this quite different series of eutectics could be classified in the same way as the metallic systems. The observations made on the organic alloys are also discussed with reference to the current theories of lamellar growth. Explanations are proposed to account for the structures formed in the other eutectic groups. EXPERIMENTAL Thin cells containing the organic alloys were uni-direction ally solidified on a specially constructed microscope stage.' Uniform growth rates were obtained by moving the cells, with a motor drive, through a fixed temperature gradient, so that the solid-liquid interface remained stationary with respect to the microscope objective lens. The cells were made by fusing two microscope cover slides 7/8 by 7/8 by 1/100 in. together on three sides, leaving a gap of 1 to 3 mils between the slides, and these were filled by surface tension. A preliminary investigation of the phase diagram between two components could be made very rapidly. One side of the cell was filled with component A and the other side with component B. Since only a small amount of mixing could occur every composition from pure A to pure B was present in the cell. When the cell was placed in the temperature gradient a pictorial representation of the phase diagram was obtained. Eutectics, peritectics, "interorganics", and solid -solid transformations could be readily detected. Fig. 1 shows part of a eutectic phase diagram. The Sample was first grown slowly then stopped. The two

Jan 1, 1967

By H. K. Najarian

This paper describes recent development work on the Wheaton-Najarian Vacuum Condenser for Zinc at Josephtown Zinc Smelter, wherein, to dissipate the heat of condensation, the "airlift" action of gases bubbling through the molten zinc in the condenser is utilized to circulate the zinc through an outside "cooling well" and cooling it continuously. AN earlier paper1 gave an account of initial development of the Wheaton-Najarian Vacuum Zinc Condenser at the Josephtown Zinc Smelter of the author's company. This paper is a progress report of further development work over the years directed toward improving the efficiency and increasing the capacity of the condenser. In this type of zinc condenser, zinc vapor with accompanying noncondensable gases from electro-thermic zinc smelting furnaces is passed upwardly through a mass of molten zinc confined in a refractory-lined U-tube. The zinc vapor condenses in the molten zinc and the noncondensable gases are drawn out of the condenser by suction applied over the surface of the molten zinc. The heat of condensation of zinc, amounting roughly to 1000 Btu per lb of zinc condensed, is absorbed by the molten zinc and, in turn, is dissipated continuously to keep the temperature of molten zinc in a range to permit effective condensation. At the time of publication of our first paper, we had at Josephtown Smelter five units of 69-in.-bore metal furnaces and one larger metal furnace having 96-in. bore. Each 69-in. metal furnace had a condenser with 22-ft overall length. The 96-in.-bore furnace had a condenser with overall length of 31 ft. Condensers were of circular cross section, with corrugated steel outer shell and carborundum lining. Diameter of these condensers was 32 in. inside the refractory lining. Molten metal in the con- denser was kept cool by spraying cold water on the outside of the condenser shell. Under good operating conditions, 22-ft condensers produced some 12 tons of metal per day; and the 31-ft condenser, about 22 tons. When the furnaces produced zinc vapor at higher rates, invariably the condenser temperature would rise to levels where excessive blue powder would form and accumulation of accretions in the condenser would be accelerated. We found that, with the system of cooling in use, we had to provide heat-exchange surface of some 150 sq ft to condense 1000 lb of metal per hr with reasonable efficiency. The wall of the condensers was made up of 5/8-in.-thick corrugated-steel shell having next to it several layers of mica and inner refractory lining of special carborundum shapes to fit the corrugation in the steel shell, and having a minimum thickness of about 2 in. Relatively low rate of heat transfer through the thick condenser wall and slow internal circulation of the molten zinc limited the rate of heat exchange between hot metal within the condenser and the cold water flowing over the outer steel shell. The thickness of the condenser wall was about minimum that we considered suitable for continuous operation. As we learned to operate the electrothermic furnaces with higher power input, producing zinc vapor at higher rates, it became apparent that we needed condensers having larger heat-exchange surfaces. Our 96-in.-bore furnace had 6 single-phase power circuits with transformers rated at 500 kva each and normally good for power input of 3000 kw.

Jan 1, 1959