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By C. M. Wayman, M. Miyagi

COMPARED to many of the binary alloys of iron, Fe-Ir alloys have received very little tud.'' Virtually nothing is known about the Fe-Ir equilibrium diagram' except for a few details concerning the liquidus-solidus positions for dilute iron-based alloys. It is reported1 that the y to a transformation temperature in Fe-Ir alloys (up to 40 wt pct Ir) is composition-dependent, varying from -900°C for pure iron to 0" to 100°C for Fe-40 pct Ir in an almost linear manner. The y to a transformation appears to be reversible,' the transformation hysteresis width increasing with increasing iridium content. In a qualitative way, the composition dependence of the y to a (and vice versa) transformations appears similar to those in the widely studied Fe-Ni system. In that the y phase (in Fe-40 pct Ir) can transform at -1000C, it

Jan 1, 1967

By J. A. Woolf, E. S. Leaver

THE purpose of this paper is to describe, in a general way, gold-dredging operations in California, with particular reference to unusual features, including types of deposits and recent attempts to improve the recovery of the gold. Dredging Areas The gold-bearing formations that traversed the western slope of the Sierra Nevadas for a north and south distance of some 300 miles furnished the immediate source of the gold found in most of the placer deposits of California. Erosion through a long period carried the gold, together with various forms of partly disintegrated material, to lower elevations and formed placer deposits. Through the classifying action of water in motion, the coarser gold and heavier material of various kinds were - deposited relatively near the source; consequently, in the higher mountain country, old river channels were worked feverishly during the early California gold-rush days because of their high gold content. With the working out of these known high-grade channels, and from the knowledge thus obtained of prehistoric stream beds, drift mining was started and flourished until about 1890. Even today many drift mines are operating with the objective of opening other old Tertiary river channels that have been covered by volcanic flows. Adjacent to these areas, which contained relatively high gold values in the older river channels, smaller particles of gold, gravel, and debris were deposited along the sides of the former stream beds and on the adjoining flat areas, thus forming the large placer deposits, which were worked principally by hydraulic mining. Following the course of the ancient rivers and of the present drainage system to the lower edge of the foothill country, extensive areas of alluvial

Jan 1, 1937

By A. Thies, Wm. B. Phillips

1. Introductory Remarks.—The Haile Gold Mine is in Lancaster county, South Carolina, 3 1/2 miles east of Kershaw station on the Charleston, Cincinnati and Chicago Railway. It was first opened about, the year 1832, and since that time has passed through various fortunes. Many different operations have been practiced here for extracting the gold : panning, grinding in Chilian mills or arrastras, stamping, the Designolle process, dry-crushing, and finally the Thies process of barrel-chlorination, which has now been in successful use for 2 1/2 years, and by which 36,000 tons of ore have been treated profitably. The Thies process is in brief the treatment of dead-roasted auriferous concentrates (pyrite, sometimes also chalcopyrite, as at the Phœnix mine, Cabarrus Co., N. C.) with nascent chlorine, without ' artificial pressure or exhaust, in lead-lined iron cylinders; the throw-

Jan 1, 1891

By C. A. Hansen

ROASTING FERRUGINOUS ZINC-SULFIDE ORES IN 1912, Mr. J. B. Ideating was developing an electrolytic-zinc process for application to the ores of the Bully Hill mines of the General Electric Co. These ores consist of blende and pyrite so finely crystallized and so intimately mixed that no mechanical separation of the individual minerals had been found possible. The ore was reduced to about 60 mesh and roasted in a hand-rabbled reverberatory furnace preparatory to leaching with sulfuric acid. The extractions obtained were quite irregular, varying from a minimum of about 70 per cent. to a maximum of about 90 per cent. This irregularity led to the construction of a small electrically heated roasting furnace, and to the study of roasting under definitely controllable conditions. From time to time, these studies have been extended to other ores. Several commercial-plant operators profess to have gained useful information from the results of these studies and it is hoped that their usefulness may be extended by this publication. EXPERIMENTAL ELECTRIC ROASTING FURNACE The furnace used for experimental work is shown in Fig. 1. One fire-clay sagger, or pot, was set within another and the space between the two filled with Silox heat insulation. The hearth is a cast-iron plate with an imbedded ribbon of nichrome wire; this wire heater is connected to a potential regulator, which permits a very close voltage control. A mechanically driven arm is fitted with rabble blades so arranged that a uniformly thick ore bed may be maintained indefinitely. This arm is usually driven at about one revolution per minute but its speed of rotation can be varied as desired. Compressed air is led into the furnace through a meter, and it was found necessary to preheat the air in order to secure the definitely isothermal conditions sought.

Jan 8, 1919

By C. A. Stetefeldt

Jan 1, 1892

By Thomas F. Torries, George H. K. Schenck

Crushed and broken stone is used directly in construction as an aggregate and accounts for about half the value and two-fifths of the quantity of natural aggregates consumed in the United States. Sand and gravel provide most of the balance of aggregates except for some lightweight materials such as pumice and expanded shale. Conditions necessary for production of crushed stone from a deposit are : 1) Quality-should pass rigid specifications for strength and durability. 2) Cost-low average total delivered cost. Construction aggregates are hard, essentially inert materials suitable for being formed into a stable mass either (1) by the addition of cementing or binding materials that produce a concrete or (2) by compaction or by natural weight to produce a road base or foundation. Aggregates usually provide about 80 to 100% of the material volume of the construction masses in which they are used. The construction industry utilizes as aggregates about 70% of all crushed stone produced in the United States according to statistics provided by the U.S. Bureau of Mines (USBM) , [Table 1], using definitions as shown below. Nonconstruction uses of crushed stone, [Table 2], are included elsewhere in Industrial Minerals and Rocks because such uses require the special physical or chemical characteristics which are discussed in those chapters.

Jan 1, 1975

By G. W. Poling

Chemical and physical properties of thiol collectors are re-examined to compare the prospects,of heavy metal-thiolate or disulphide surface reaction products acting as actual collector species. Recent evidences for the existence and importance of each of these types of adsorbed species on sulphide minerals are also discussed. A conclusion is reached that partial coverage by chemisorbed heavy metal thiolate is often sufficient to confer practical levels of hydrophobicity and floatability. Only on a few highly conducting and "noble" sulphides does adsorbed disulphide-type collector oxidation product appear to be significant.

Jan 1, 1976

By B. G. Klugh

In a paper before the Institute at Wilkes-Barre, Pa., June, 1911,' Mr. James Gayley discussed the application of this process to iron-bearing materials. The same author² described the results of operations at the plant at Birdsboro, Pa. The purpose of the present paper is to present further discussion of some techuical details involved in the operation of this plant, and of the theoretical and practical relations of this product to blast-furnace practice. Since Oct. 1, 1911, the Birdsboro plant has been in operation at the blast-furnace of the E. & G. Brooke Iron Co. The results have been highly satisfactory, although the material treated, being chiefly the flue-dust currently made by the furnace or taker] from the accumulated stock-pile, was excessively high, and yet not uniform, in carbon, so that the desirable control or regularity of the amount of fuel in the mixture treated could not be maintained. Nothing could more forcibly demonstrate the flexibility of the process than the fact that, under these conditions, the sinter produced was, in all cases, of excellent quality. The Dwight & Lloyd process, as such, slid its present highly-developed mechanical appliances were described by Mr. Gayley in the paper above mentioned. While the repetition of some particulars will be unavoidable in this paper, it will be confined to features bearing upon the metallurgical principles involved. According to the principle of the process, the finely-divided iron-bearing material to be sinterecl is intimately nlixed with

Jan 1, 1913

By J. A. Herbst

During the last decade it has been established that conventional mineral-processing control strategies based on classical control theory result in significant increases in plant throughput and operating-cost savings. It has, however, also been recognized that conventional strategies have important limitations for complex multivariable mineral-processing systems. These limitations center around the fact that single-input/single- output control linkings often result in highly undesirable interactions between controllers. During the last few years new and promising approaches to solving this problem have emerged. These approaches are based on the use of on-line dynamic models to make predictions which are useful for control decision-making. This paper presents a brief summary of the state-of-the-art for mineral-processing control in 1984. This summary is followed by a review of recent developments in model-based control strategies including those in optimal control, self- tuning regulators and decoupling control. Expected trends for the future in the control of mineral-processing operations are discussed.

Jan 1, 1984

By J. W. Leonard, J. C. Anderson, C. T. Holland

PREPARATION CONTROL IN UNDERGROUND MINING Selective Mining According to district Depending upon the particular geographic location or seam characteristics modem raw coal preparation practices can be used to obtain improved product quality and uniformity. Nevertheless, certain coal markets may require only marginal quality while others may require very high quality and these objectives may be sought by commencing the preparation of coal underground at the "working face." Underground preparation involves choosing those portions of the bed which can be cleaned to satisfy predetermined market requirements involving (1 ) maintenance of uniformity in chemical quality, (2) elimination of removable impurities, (3) control of sizes and size ratios and (4) control of moisture. The methods employed to attain these objectives vary widely with the (1) seam under development, (2) mining equipment available and (3) changing trends in the consuming markets. When a mining property is opened and development progresses from one section to another the (1) petrography of the coal in the bed does not re- main uniform, (2) character of roof and floor are subject to change and (3) character and prevalence of mineral impurities are subject to considerable variation. The quality of coal shipped to market from any mine depends upon intelligent foresight, planning, execution and supervision. Mining becomes a highly technical art. The quality of coal as determined by chemical and petrographic analysis is without question one of the most important considerations in the development and life of any coal-mining property. Variations in such proper- ties as volatile matter, ash, sulfur, Btu content and petrography are of considerable interest and to a limited extent so are such properties as phosphorous content, free swelling index, plasticity, hardness, pressure formation during coking and ash composition. The maximum and minimum specifications of these characteristics as established by competitive market conditions place definite limits on the marketability of a coal. The prospecting and evaluation of any area containing one or more salable coal beds by means of channel samples taken from outcrop openings and/or from diamond-drill cores can yield valuable data on coal characteristics. By correlating the data developed from distinct petrographic sections of channel and/or drill core samples, the quality of the bed according to stratification will be evident. There are few coal beds that do not show wide variations of such characteristics as ash and sulfur

Jan 1, 1968

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 A. D. Hodges

The great mining region of Peru is a mountainous belt of country, running nearly the whole length of the republic, and comprising the two grand ranges of the Andes with the elevated table-lands between them. On the east of this belt are the extensive plains and fertile valleys of the Amazon and its tributaries. On the west is a narrow strip of coast 20 to 50 miles wide, for the most part a sandy desert, but producing abundant crops where irrigated ; and here are found petroleum (Department of Piura), salt (at Huacho and elsewhere), nitrate of soda in enormous amounts at the south, silver in a few localities (Province of Tarapaca), copper and other mineral products. The Western Cordillera, running nearly parallel with the shoreline, rises like a wall on the eastern side of the coast-belt, with passes from 15,000 to 18,000 feet high and peaks attaining 18,000 to 20,000 feet. Further east, at a varying distance, is the Eastern Cordillera, composed of broken mountain ranges which, considered as one group, have a general parallelism with the western chain, but individually vary greatly in direction, sometimes running nearly east and west, in places projecting out into the Amazonian lands, or here and there curving around to unite with the western ridge, and with this enclosing immense inter-alpine plains. These general features are indicated in Fig. 1. The surface of these plains is uneven and traversed by lower ranges of hills which surround large lakes, or rolling pampas, or fertile valleys; and through many of these last run rivers of considerable size. The whole country has a high altitude (averaging up to 15,000 or 16,000 feet), and slopes gradually north and east towards the Amazon, into which drain all its waters. Its bounding mountain chains are scored on all sides by narrow, picturesque and pre-

Jan 1, 1888

By AIME AIME

The American Society of Mechanical Engineers.-The semi-annual meeting of the American Society of Mechanical Engineers will be held in Detroit, Mich., June 23-26. A session will be devoted to hoisting- and conveying-machinery; and many other subjects will be treated in professional papers, among which are . Clutches (with special reference to automobile clutches); The Thermal Properties of Superheated Steam; The Horse-Power, Friction-Losses, and Efficiency of Gas- and Oil-Engines; A Journal-Friction Measuring-Machine; A Simple Method of Checking Conical Pistons for Stress, and The By-Product Coke-Oven. The usual receptions will be held and excursions will be made to manufacturing plants, the slip-building yards, and various points of interest in and around Detroit. Among the excursions' planned is one to the University of Michigan at Ann Arbor. The Gas-Power Section of the Society will hold a session, and the Society for the Promotion of Engineering Education and the Society of Automobile Engineers will hold meet-

Jan 5, 1908

By C. H. Herty, J. L. Keats

In the literature on the elimination of metalloids in basic open-hearth practice, there are a great many heats recorded in which excellent data on changes in slag and metal composition during refining are given, but in almost all of these heats either temperature data or weights and analysis of charge are unrecorded and observations on the physical characteristics of the slag are almost always lacking. With these points in mind, a test heat was made in which as complete data as possible on all the factors that affect the elimination of metalloids were obtained. The Test Heat The test heat was made in a standard 100-ton stationary furnace at the Lackawanna Steel Co., Lackawanna, N. Y., on January 17, 1922. The Charge—Scrap.—The scrap consisted entirely of rail-heat butts, selected from a number of heats made the week before the test. The average analysis of the scrap was calculated from the analysis of these heats and from the weight of scrap from each heat. Pig Iron.—Two ladles of pig iron were used in the charge and two samples were taken from each ladle as it was poured into the furnace. These four samples were composited for the average pig-iron sample. Other Materials.—Weights of dolomite, ore and spar were obtained by weighing a quantity of each just before the test and weighing the amount of each left after the heat was completed. The limestone. was weighed on the charging pans. Coal for recarburizing, ferromanganese, ferro-silicon and aluminum were weighed out as used. All these materials were carefully sampled before the test was begun. Coal consumption at the producers was obtained by getting the average capacity of the hoppers that fed the producers, and then counting the number of hoppers of coal used during the course of the heat. Products Steel.—The steel made was rolled into billets, the rolling properties being very satisfactory. The weight of steel was obtained by taking a

Jan 1, 1926

By J. T. Norton, N. J. Grant, A. M. Gervais

An investigation of the creep deformation of coarse-grained high-purity aluminum at temperatures approaching the melting point permitted the formulation of a theory of subgrain formation. Subgrain boundaries were found to be formed by two different processes: kinking and polygonization. Polygonization is considered as the main factor in subgrain formation. SINCE "slipless flow" was first discussed in detail by Hanson and Wheeler,' many studies have been undertaken to determine how metals deform at high temperatures. Several types of observations have been reported. Jenkins and Mellor,² working on the creep of mild steels and various grades of commercial irons, found metallographic evidence of a kind of substructure within the grains after deformation at high temperatures. Homes" observed after creep deformation of steel at high temperatures that the original X-ray spots were sharply divided into several small ones. The same phenomenon was reported by Hirst4 from his studies on lead and later by Crussard5 from his work on aluminum. The works of these investigators demonstrated beyond any doubt that the splitting of the X-ray spots was due to the fact that the grains underwent a division into subgrains during deformation at high temperatures. Since then, numerous experiments have been undertaken on aluminum in order to determine the mechanism of formation of subgrains. Research workers can be divided, for the purpose of discussion, into two different groups as regards thinking on subgrain formation. On one hand, based on the work on polygonization by Cahn,6 Guinier and Lacombe,7 Greenough and Smith," Crussard,10,11 and Servi, Norton, and Grant," it was concluded that subgrain formation was a consequence of the simultaneous effects, first, of inhomogeneous deformation which produced bending of the lattice, and second, polygonization. On the other hand, Wood and coworkers13-16 based their work on the results of an earlier report" which dealt with crystallite size and a fragmentation theory. It is interesting to note that while Greenough and Smith8 and Wood et al. performed similar experiments, their conclusions were quite different. Wood et al. did not recognize polygonization as a fundamental mechanism and said that aluminum, at the beginning of the deformation, fragmented immedi- ately into subgrains in order to permit deformation of the metal, the number of these subgrains being a function of strain rate and temperature. They concluded that deformation of grains occurred by flow along the subgrain boundaries. In view of the contradictory conclusions, it would appear that the data were not explicit enough to provide an unambiguous conclusion. It appears that the techniques by which most of the results were obtained, namely, X-ray work, were not enough by themselves to solve the problem. Another approach was needed. In the present research, therefore, an extensive metallographic study was planned to supplement the X-ray work. The importance of revealing the subgrain boundaries metallographically was realized, and this will explain the extensive development and use of etching techniques. In order that subgrains would be considerably larger and therefore more readily visible under a microscope, the creep experiments were performed at very high temperatures approaching the melting point of aluminum. Development of Experimental Technique Creep tests were run at constant load on high purity (99.995 pct) aluminum specimens having a very coarse grain size. None of the specimens was run to fracture. The specimens were originally round (diameter, 0.187 in.; gage length, 1 in.) and had parallel flats milled in the gage section to permit

Jan 1, 1954

By Joel Watkins

THE terms kaolin, china clay, ball clay, and paper clay are more or less loosely and interchangeably applied to a large class of white-burning clays. These clays are made up chiefly of hydrous amorphous (colloidal) aluminum silicates with variable amounts of free silica and other impurities in small quantities. Occasionally also the term kaolinite is wrongly applied to a white-burning clay, for kaolinite, is a mineral of definite chemical composition and definite crystalline form which occurs but sparingly in nature. It is not the purpose of this paper, however, to define or classify clays, or to enter into a discussion of the chemistry of clays. It is rather a general description of the occurrence and methods of mining of a kindred group of clays, and a discussion of their future economic aspect. In the Southern Appalachian States, the mining of white-burning clays has in recent years become an important industry. Although these clays are of several distinct types, which occur in as many localities under different geologic conditions, they are for the most part. primarily of the same origin. They are essentially the same in elementary constituents, and are largely consumed in the same industrial arts. From the standpoint of a mining engineer, therefore, and for convenience in comparison and correlation, it should be interesting to discuss them under one heading.

Jan 2, 1915

By T. Egleston

THE ores of mercury of North California are composed of metallic mercury and cinnabar. They are found in serpentine, and are very often associated with chalcedony, in masses more or less irregular, often concentrated enough, however, to furnish ores yielding from three to ten per cent., and sometimes richer. This deposit makes its appearance in Vallejo where it has been worked. North of here the mines are more developed. Most of the quicksilver mines, how¬ever, are situated in Sonoma and Napa Counties. On its outcrop the serpentine rocks have become decomposed, and have often been washed away to a considerable depth, so that in many cases in their neighborhood, what is apparently nothing but ordinary dirt, will frequently contain from two to three per cent. of metallic mercury, with but a trace of cinnabar, in which case, as at the Sonoma mine, it is made up into adobes and distilled. Such material does not require to be mixed with dirt to be made into adobes. Very often, also, the outcrop of the rock, where it is not decomposed, is filled with metallic mercury, so that by striking a pick into it, as at the Rattle-snake mine, a pound or more of mercury at a time will sometimes spurt out. Such rock as this is found in several localities in every stage of impregnation, and usually makes very rich ore. There is generally, however, very little of it, and it is found only in the first workings ; the ore in depth is always cinnabar. At the Rattlesnake mine near Pine Flat, where large quantities of metallic mercury are found, the rock contains so much petroleum that it has been necessary to make special arrangements to burn the carbides of hydrogen, since the distillation of the petroleum causes an extra quantity of poor soot to be formed in the condensation-chambers. At the Geysers the ore is associated with large quantities of sulphur and gypsum, so that in a hand specimen there is often more sulphur than cinnabar, which is a serious impediment to working, especially for the modern style of furnace with iron condensers, and causes so much soot to be formed that it has been known to penetrate as far as the blower, and to so completely clog it as to prevent its revolution. The ore coming from the mine is more or less hand-picked. In one or two cases attempts have been made to treat the poorest, and especially the very fine ores, mechanically as at the California works.

Jan 1, 1875

By Thomas Egleston

The ores of mercury of North California are composed of metallic mercury and cinnabar. They are found in serpentine, and are very often associated with chalcedony, in masses more or less irregular, often concentrated enough, however, to furnish ores yielding from three to ten per cent., and sometimes richer. This deposit makes its appearance in Vallejo where it has been worked. North of here the mines are more developed. Most of the quicksilver mines, however, are situated in Sonoma and Napa Counties. On its outcrop the serpentine rocks have become decomposed, and have often been washed away to a considerable depth, so that in many cases in their neighborhood, what is apparently nothing but ordinary dirt, will frequently contain from two to three per cent. of metallic mercury, with but a trace of cinnabar, in which case, as at the Sonoma mine, it is made up into adobes and distilled. Such material does not require to be mixed with dirt to be made into adobes. Very often, also, the outcrop of the rock, where it is not decomposed, is filled with metallic mercury, so that by striking a pick into it, as at the Rattlesnake mine, a pound or more of mercury at a time will sometimes spurt out. Such rock as this is found in several localities in every stage of impregnation, and usually makes very rich ore. There is generally, however, very little of it, and it is found only in the first workings; the ore in depth is always cinnabar. At the Rattlesnake mine near Pine Flat, where large quantities of metallic mercury are found, the rock contains so much petroleum that it has been necessary to make special arrangements to burn the carbides of hydrogen, since the distillation of the petroleum causes an extra quantity of poor soot to be formed in the condensation-chambers. At the Geysers the ore is associated with large quantities of sulphur and gypsum, so that in a hand specimen there is often more sulphur than cinnabar, which is a serious impediment to working, especially for the modern style of furnace with iron condensers, and causes so much soot to be formed that it has been known to penetrate as far as the blower, and to so completely clog it as to prevent its revolution. The ore coming from the mine is more or less hand-picked. In one or two cases attempts have been made to treat the poorest, and especially the very fine ores, mechanically as at the California works.

By Thomas L. Kesler

Essentially all of the barite produced in Georgia has come from the Carters-ville district in the northwest part of the state. The earliest recorded shipment of ore, 60 tons, was made in 1894.' With the exception of the four-year period 1931 to 1934, the separate yearly output has been recorded and published since 1915, whereas the total yearly output of the United States has been published since 1880. The separately recorded production of Georgia (Cartersville) through 1947 is 2,232,544 short tons valued at $14,900,746,2 but unpublished data on the period 1931 to 1934, plus the estimated unrecorded output prior to 1915, make the actual total about 2,400,000 short tons. This is about 21 pct of the total production of the United States, which, through 1947, is 11,328,440 short tons valued at $71,683,386.2 The barite-producing part of the Cartersville district is relatively small, having from north to south a length of 4.5 miles, and a width of 2 miles. This small area, containing 35 barite mines, is the source of practically all of the barite produced in the state. The area is hilly, and has a total relief of 500 ft. The west-flowing Etowah River crosses the middle of the area, and is an unfailing source of water for operations on properties near its course. Opencut mining is carried on during the entire year, but is hampered by rain in the winter and early spring. Three railroads, two U.S. highways, and a network of graded roads provide access to and within the district, as well as excellent shipping facilities for ore and supplies. In addition to the barite, the district contains deposits of manganese, brown iron, ocher, umber, and specular hematite. Geologic Setting The area containing the barite deposits is underlain by Lower Cambrian rocks and their weathered residua. These rocks are grouped in three formations; in ascending order, these are the Weisner, the Shady, and the Rome. The Weisner formation consists mainly of finely micaceous metashale containing many random beds of quartzite, a few beds of conglomerate and metasiltstone, and beds of crystalline limestone that is apparently scarce. The formation is more than 1000 ft thick, and the base is not exposed. On account of their resistance to weathering, the rocks of the Weisner formation have sustained the higher elevations and therefore crop out on the ridges that characterize the area. Nearly all of these ridges are underlain by asymmetric anticlinal folds, and conversely the intervening valleys are underlain by synclinal folds. A diagrammatic section, showing typical mode of exposure of the Weisner rocks and their relation to overlying formations, in the limb of a fold, is shown in Fig 1. The Shady formation here consists of a lithologically distinctive series of variably siliceous specular hematite beds and thin beds of dolomite, which in places contain abundant fossils. In the zone of weathering, the dolomite has been leached and most of the hematite hydrated to ocherous and umber-ous clays, hut bedding planes in these weathered materials are commonly well preserved with or without distortion effected by slumping. This preservation of structure during weathering is lacking in the residuum that rests on the Rome dolomite, which is described below. The maximum thickness of the

Jan 1, 1950

US 4,192,851-Recovery of elemental sulfur and the metal values from a complex sulfide ore containing two or more of the metals zinc, lead, copper, silver, gold and/or other metals. A mixture of ore and sulfuric acid and/or spent electrolyte is flowed at optimum temperature and pressure in a quiescent zone to dissolve selected metals and sulfur and coalesce the sulfur. The coalesced sulfur and unreacted sulfides are separated by flowing the leach slurry with an upward velocity component The separated materials are discharged and further processed by conventional methods as war- ranted. H.E. Hirsch, J F. Higginson, EG. Parker, and G M Swinkels, assigned to Sherritt Gordon Mines Ltd. Mar. 11, 1980. 6 pp. (423-28) Filed. 3-14-78 (886,368). Priority. United Kingdom, 3-15-77 (10800/77).

Jan 1, 1982