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By R. F. Hehemann, R. H. Goodenow

Thermal arrest, hot-stage microscopy, and transtnission electron microscopy techniques have been employed to study the transformations in low-carbon iron and Fe-9 pct Ni alloys. In continuous cooling experiments, each alloy transforms at an essentially constant temperature for cooling rates below the critical rate required for martensite formation. However, high-tenzperature transformation in pure iron takes place by a different mechanism than that in the 9 pct Ni alloys. Pure iron exhibits an equi-a a structure with a low and random dislocation density while the 9 pct Ni alloy exhibits a cell or lathlike substructure analogous to that of low-carbon martensite. This same substructure characterizes upper bainite in higher-carbon inaterials. UNTIL relatively recently, diffusionless transformations have been considered to take place by the same mechanism and have been termed mar-tensitic transformations.l-3 The most characteristic feature2 of this mode of transformation is the shape change produced by a shear deformation and growth of the product phase frequently occurs at an extremely high velocity approaching that of an elastic wave.4'5 A different mechanism of diffusionless transformation was recognized first in Cu-Ga and other copper-base alloys.6,7 From the absence of surface tilting in these alloys, it has been concluded that transformation is not accomplished by the cooperative shear displacements that occur in mar-tensitic reactions. Transformation presumably takes place by the rapid movement of an incoherent interface which is capable of propagating across parent grain boundaries. Although the transformation is diffusionless in the macroscopic sense, advancement of these interfaces is accomplished by an atom by atom rearrangement. Transformations of this type therefore require thermal activation and are generally operative only at high temperature. Although requiring short-range diffusion at the interface, propagation still occurs so rapidly that the reaction cannot be suppressed with normal cooling rates.7 The resulting microstructures exhibit large, irregular-shaped regions of the product phase, which are essentially free of crystallographic features. Consequently, these reactions have been termed massive transformations. Transformation by the massive mechanism has been reported to occur in ferrous systems involving pure iron and binary alloys of iron with nickel, chromium, and silicon by Gilbert and owen.' The Fe-Ni system is of special interest in that the massive transformation was observed in alloys with less than 15 pct Ni while alloys having more than about 28 pct Ni transformed by the conventional mar-tensitic mechanism. By employing cooling rates substantially higher than those used by Gilbert and Owen, Swanson and Parr have been able to suppress the massive transformation in alloys with 0 to 10 pct Ni9 and produce martensite as revealed by surface relief. The massive transformation in the alloys having less than 15 pct Ni was identified by the lack of surface relief and an irregular rather than clearly acicular microstructure.' Speich and Swann, using thin-foil electron microscopy, identified three distinctly different structures10 in quenched binary Fe-Ni alloys. From 0 to 4 pct Ni the structure consisted of blocky grains of a with a low and random dislocation density. Alloys with 4 to 25 pct Ni exhibited a cell structure with a high dislocation density; and at greater than 25 pct Ni the structure consisted of internally twinned plates. The structural change at approximately 4 pct Ni suggests that alloys with low nickel content transform by a different mechanism than those with intermediate nickel contents and the transition from the cellular to the internally twinned structures at approximately 25 pct Ni is analogous to the transition from needles to internally twinned plates that occurs over a narrow range of carbon contents in Fe-C martensites.11,12 Conventional bainitic and martensitic modes of austenite decomposition operate in ternary Fe-C-Ni alloys having less than 10 pct Ni. This investigation was conducted in order to explore the conditions under which the massive, bainitic, and martensitic transformations occur and the relationships between these modes of decomposition.

Jan 1, 1965

By John C. Calhoun, Raymond G. Loper

Theoretical calculations for the decline of pressure and the variation of instantaneous producing gas-oil ratio with increased cumulative production have been made for reservoir systems under various producing drawdown values and for various spacings. These variables have been included by a modification of previously Published techniques. This consists essentially of utilizing a radial system flowing gas and oil in a succession of steady state calculations. The results of the calculations do not show any variation in the predicted behavior of the internal gas drive reservoir when either the drawdown or the spacing are changed. The prediction of performance on an internal gas drive reservoir has been presented by various authors. ',"' These predictions are in the form of a pressure decline and an instantaneous producing gas-oil ratio as a function of cumulative oil withdrawal. In making these predictions a basic assumption has been that the saturation of the reservoir is uniform throughout at any time, or that the pressure differential imposed on the reservoir system is zero. Because of these assumptions the validity of such predictions has been questioned. Their application to actual systems, where saturations are not uniform and where producing differentials exist, has been a hazardous procedure. The authors cited have used different methods of approach to the derivation of equations for making their predictions and for arriving at a solution of both equations, but basically the same relationships are utilized in each case. In all instances the instantaneous producing gas-oil ratio is calculated from the equation: In utilizing this equation an average reservoir pressure and an average reservoir saturation must be known, the former to define ß, v, s, and uo/ug and the latter to define kg/ko. Predictions can be made, therefore, only for the conditions of a uniform reservoir saturation and a uniform reservoir pressure. This restriction of requiring a uniform oil saturation can be resolved by applying two-phase steady state flow for the radial system to the reservoir's history. Radial steady state flow is defined when the ratio of phases flowing,

Jan 1, 1949

By John C. Calhoun, Raymond G. Loper

Theoretical calculations for the decline of pressure and the variation of instantaneous producing gas-oil ratio with increased cumulative production have been made for reservoir systems under various producing drawdown values and for various spacings. These variables have been included by a modification of previously Published techniques. This consists essentially of utilizing a radial system flowing gas and oil in a succession of steady state calculations. The results of the calculations do not show any variation in the predicted behavior of the internal gas drive reservoir when either the drawdown or the spacing are changed. The prediction of performance on an internal gas drive reservoir has been presented by various authors. ',"' These predictions are in the form of a pressure decline and an instantaneous producing gas-oil ratio as a function of cumulative oil withdrawal. In making these predictions a basic assumption has been that the saturation of the reservoir is uniform throughout at any time, or that the pressure differential imposed on the reservoir system is zero. Because of these assumptions the validity of such predictions has been questioned. Their application to actual systems, where saturations are not uniform and where producing differentials exist, has been a hazardous procedure. The authors cited have used different methods of approach to the derivation of equations for making their predictions and for arriving at a solution of both equations, but basically the same relationships are utilized in each case. In all instances the instantaneous producing gas-oil ratio is calculated from the equation: In utilizing this equation an average reservoir pressure and an average reservoir saturation must be known, the former to define ß, v, s, and uo/ug and the latter to define kg/ko. Predictions can be made, therefore, only for the conditions of a uniform reservoir saturation and a uniform reservoir pressure. This restriction of requiring a uniform oil saturation can be resolved by applying two-phase steady state flow for the radial system to the reservoir's history. Radial steady state flow is defined when the ratio of phases flowing,

Jan 1, 1949

By W. D. BRENNAN

FOR a considerable number of years past, there has been a shortage of experienced coal miners at the coal mine of the Phelps-Dodge Corp. This is probably due, to some extent, to the mines being so far south of the main western coal producing regions, so that experienced men secure employment before reaching this point. These mines are at Dawson, New Mexico, which is in Colfax County, near the Colorado line. The district is known as the Raton field, and the seam being worked is known as the Raton or Blossburg seam. The mines operated are Nos. 1 to 6, 8 and 9. The daily out- put at the present time, with restricted operations, is about 4000 tons, but the daily capacity is about 5500 tons. The mines are so grouped that the coal is dumped over four tipples. The mines are about twenty-five years old and extend as much as three miles under ground; they are all drift openings, with trolley, storage battery, and mule haulage. At the same time that the shortage of miners existed there was a surplus of common labor seeking employment. We learned that the Copper Queen. Branch of Phelps Dodge Corp. conducted a training school in one of its mines which had worked out very satisfactorily, and thus gained the idea of attempting such a school in the coal mines at Dawson.

Jan 1, 1929

By C. T. Malcomson

An elaborate series of experiments has been conducted during the past three years at Irvington, N. J., which has resulted in the perfection of a process for the manufacture of smokeless fuel from high-volatile coals, and for the recovery and refinement of the coal-tar products derived therefrom. These experiments have been financed by Messrs. Blair & Co., of New York, and were conducted under the direction of Charles H. Smith, a member of this Institute, and the inventor of the process. The low-temperature distillation of coal has interested investigators for many years. Sporadic attempts have been made to solve the mechanical problems, but until the Smith process was developed, they were not carried to conclusions of economic value. The present coal shortage and the increasing demand for smokeless fuels make this subject one of timely interest. DescRiption of Plant The following equipment was installed and operated during the experimental period: Four horizontal and two vertical units of commercial size for the low-temperature distillation of the coal; two vertical, two horizontal, and two inclined benches for distillation of the briquets at medium and higher temperatures; presses and auxiliary equipment necessary for making briquets; and a complete byproduct recovery and tar-refining plant. This commercial equipment is provided with gas and electric meters, pyrometers and other apparatus for recording accurately the results of all experiments. There is, in addition to the commercial equipment, a complete chemical laboratory with distillation and recovery apparatus, including facilities far refining and cracking the tar and measuring the yields and calorific value of the gas. This apparatus makes possible a study on a small scale, of the various problems involved in the process. Description of Process Mr. Smith's experiments have resulted in the production on a commercial scale of: 1. A fuel, called Carbocoal, which, for convenience in handling, is prepared in briquet form.

Jan 1, 1920

By T. H. Janes

NATURAL abrasives of some type are found in all countries of the world. In order of their hardness the principal natural abrasives are diamond, corundum, emery, and garnet, which are termed high grade, and the various forms of silica, including pumice, pumicite, ground feldspar, china clay and, most important, sandstone. The properties qualifying materials for use as abrasives are hardness, toughness, grain shape and size, character of fracture, and purity or uniformity. For manufacture of bonded grain abrasives such as grinding wheels, the stability of the abrasive and its bonding characteristics are also important. No single property is paramount for all uses. Extreme hardness and toughness are needed for some applications, as in diamonds for drill bits, while for other purposes the capacity of the abrasive to break down slowly under use and to develop fresh cutting edges is of greatest importance, as with garnet for sandpaper. In dentifrices, soaps, and metal polishes, of course, hardness and toughness are objectionable. First among the natural abrasives, industrial diamonds are essentially of three types: l—bort, which includes off-color, flawed, or broken fragments unsuitable for gems; 2—carbonado, or black diamond, a very hard and extremely tough aggregate of very small diamond crystals; and 3—ballas, a very hard, tough globular mass of diamond crystals radiating from a common center. Bort comes from all diamond-producing centers, carbonados only from Brazil, and ballas chiefly from Brazil, although a few of this last group come from South Africa. By far the largest producer of industrial diamonds is the Belgian Congo; the Gold Coast, Angola, the Union of South Africa, and Sierra Leone supply most of the remainder. There is no production in Canada, which imports $6 to $9 million worth of industrial diamonds annually. Industrial diamonds find innumerable uses in modern industry. They are used for diamond drill bits for the mining industry; in diamond dies for wire drawing; in diamond-tipped tools for truing abrasive wheels and for turning and boring hard rubber, fibers, and plastics; and in diamond-toothed saws for sawing stone, glass, and metals. High-speed tool steels, cemented carbides, and other hard, dense alloys can be cut, sharpened, or shaped efficiently only with diamond-tipped tools and diamond grinding wheels. .. Second only to the diamond in hardness is corundum, an impure form of the ruby and sapphire gems consisting of alumina and oxygen (Al²O³) with impurities such as silica and ferric oxide. Corundum generally crystallizes from magmas rich in alumina and deficient in silica, as in the nepheline syenites of eastern Ontario. Grain corundum is used in the manufacture of grinding wheels; very coarse grain is used in snagging wheels. Both types of wheels are employed in the metal trades, where the hardness of corundum, coupled with its characteristic fracturing into sharp cutting edges, makes it an ideal cutting tool. The finest corundum (flour grades) is used for fine grinding of glass and high-precision lenses. From 1900 to 1921 Canada was the world's leading producer of corundum. Following this period the deposits located in northern Transvaal of the Union of South Africa supplied more and more of the world's requirements, and since 1940 South Africa has provided almost the entire output, which has ranged between 2500 to 7000 tons a year during the last decade. Minor amounts have also been produced in Mozambique, India, and Nyassaland. Opportunities for Mining Corundum Corundum deposits in southeastern Ontario are of three types, which may be described as follows: 1—Scattered, irregularly-shaped deposits of coarse-grained corundum which could be mined by means of small pits. About 10 groups of such deposits are known. Although the tonnage of individual deposits of this type is not great, it has been estimated that several years' ore supply is available for a small tonnage operation. Deposits average about 9 pct corundum. 2—Large irregular deposits of coarse-grained corundum which would require mining by adit with possibly a scavenger operation on the remains of former surface deposits. The Craigmont deposit of this type produced about 20,000 tons of corundum concentrate during operations between 1900 and 1913. Most of the readily available surface ore was removed by operators during that time. Reserves of ore above road level have been estimated to average 7 pct corundum, but none of the so-called reserves have been blocked out, or even indicated, by diamond drilling. From 1944 to 1946, 2025 tons of

Jan 1, 1955

By Frederic Benard

The treatment of Balbach-Thum slimes at Copper Cliff by the Ontario Refining Co, is of interest because it differs considerably from methods usually employed for the recovery of fine gold from parting-plant slimes. Owing to the comparatively high percentages of palladium and platinum, wet methods are used to remover the greater proportion of these metals before electrolytic refining in the Wohlwill cells. The Plant The platinum-metals department, Wohlwill room, and gold-melting room extend along the north side of the silver refinery and are separated from the parting plant by a glass partition (Figs. 1 and 2). The platinum-metals department resembles a laboratory built on a large scale, with the various pieces of equipment laid out on terraces to facilitate handling. Because of the corrosive nature of the solutions, chemical stoneware is used throughout. Elevation of acids is accomplished by means of Mariotte bottles. On the top level are three steam-jacketed stoneware kettles of 50-gal. capacity, also a packed tower. One kettle is used for digesting the slimes while the remaining kettles are used for precipitating the gold. The dissolver is equippcd with a treated concrete hood, which is connected to the flue system. Gases are drawn off through the packed tower by means of a 6-in. stoneware exhaust fan. A 15 per cent solution of sodium carbonate is continually circulated through the tower. On the intermediate level are two suition filters, one for removing silver chloride and the other for the gold sand. The filter medium consists of an asbestos pad covered with a filter paper on which is a layer of twill. On the bottom level are two rectangular cementation tanks, 24 by 48 by 24 in. deep, and a suction filter used for removing the platinum-metal concentrates. The circulating pump for the packed tower is also here. Suction is provided by a vacuum pump having a capacity of 8 cu. ft. at 20-in. vacuum.

Jan 1, 1944

By J. H. L. Vogt

TABLE OF CONTENTS. PAGE Introduction,...........125 I. The Original Source of the Heavy Metals of Ore-DepoBits,. 126 Distribution of Elementary Substances in the Earth's Crust,. . 128 11. The Relation between Eruptive Processes and the Formation of Ore-Deposits, Especially Buch AS have been Produced by Eruptive After-Actions,........ Ore-Deposits Formed by Magmatic Segregation,..... Ore-Deposits Formed by Eruptive After-Actions,..... Cassiterite-Veins and Apatite-Veins,...... Ore-Deposits of Contact-Metamorphic Origin,.... Pyritic Deposits,.......... Veins of Gold, Silver and Lead-Ore,......142 Conclusions,........... 111. The Nature of the Ore-Solutions in Vein-Fissures, and the Metasomatic Alterations along the Ore-Veins,. .. 147 The Association of Vein-Minerals,.......147 Deposition of the Vein-Minemls,........148 Alteration of the Country-Rock,........ Classification of Metasomatic Alterations,...... 149 Additional Observations,......... Kaolinization,..........150 Comparison between Cassiterite-Veins and Lead-Sulphide Veins,. 154 Comparison between Formation of Greisen, etc., and Propylitiza tion, etc.,........... Conclusions,........... IV. Differences of Depth in the Original Positions of EPIGENETIC Deposits ; and the Secondary Alterations of Deposits,. . 158 Original Differences of Depth,. .. .. .. . Gecondary Altemtions of Ore-Deposits,......, Introduction. In the latter part of November, 1900,I received through the Secretary of the Institute the papers of Messrs. Van Hise, Emmons, Lindgren and Weed, presented at the Washington meeting of February in that year, with the request (urged also by Mr. Emmons) that I would furnish for the Richmond meet-

Jan 1, 1902

By G. R. Wilms

A study has been made of the structural changes in polycrystalline high purity aluminum during the tertiary stage of creep under conditions of constant tensile load. It appears that there is no basic modification in the particular mechanism of deformation that characterized the preceding secondary stage of creep, but that the changes in crystalline structure produced during the tertiary stage are only a consequence and not a cause of the accelerated strain. Intercrystalline fissures were observed on entry into the tertiary stage, and these might supplement the accelerated rate of strain owing to local stress concentrations. There is evidence that the formation of these fissures may be associated with the presence of surface imperfections, and it is suggested that a more generalized treatment of the results may explain certain creep characteristics of commercial alloys. IN previous work'-4 a study was made of the changes produced when specimens of annealed aluminum were deformed at various temperatures and rates of strain, especially under conditions leading to creep under constant tensile load. It was shown that, as the temperature was increased or as the rate of strain was decreased, elements of the substructure produced within the grains became coarser, and with the strain rate constant at a given temperature, their size tended to an equilibrium value. The preliminary process of the breaking down of the grains into a substructure was identified with primary creep.' The subsequent equilibrium, condition was associated with secondary creep. The question then arose whether the tertiary stage corresponded to any further significant change in the substructure. The question is also of interest in view of the opinion, expressed for instance by Andrade,5 that the tertiary stage is merely an accelerated rate of strain due to the reduced area of section of a specimen under continuous tensile load, and the other opinion, as suggested by the observation by Sully, Cale, and Willoughby6 of a tertiary stage in com-pressive loading, that this third stage is a real effect in its own right. The object of this paper is to record some observations on the tertiary stage of high purity aluminum. Experimental Procedure The material was aluminum of 99.98 pct purity as previously used. The specimens had a rectangular section of l/8 x l/2 in., and extensions were measured over a 1 in. gage length. After machining to shape, the specimens were annealed to give a standard grain size of 0.2 mm and then electropolished. The general procedure involved metallographic and X-ray diffraction examination at progressive stages of elongation (marked by arrows on the curves shown in Figs. 1 and 2), the specimen being extended to fracture under constant load at a given temperature. The X-ray tests were made by the back-reflection method from a stationary specimen, using CoK radiation. The longer edge of the micrographs in the paper corresponds to the direction of applied stress. Results The previous work showed that, in the secondary stage of creep in aluminum, three basic types of structure could be developed according to the temperature and rate of strain. These were: 1—slip, which predominated at the lower temperatures and higher rates of strain and produced the finest and least perfect substructure; 2—cell structure, which superseded slip as the temperature was raised and the rate of strain decreased and which was characterized by a coarser and more perfect structure and an absence of slip lines; and 3—a stage termed "boundary microflow," which predominated at still higher temperatures and lower rates of strain when the cell size had increased and become comparable

Jan 1, 1955

By Frederic Benard

THE treatment of Balbach-Thum slimes at Copper Cliff by the Ontario Refining Co, is of interest because it differs considerably from methods usually employed for the recovery of fine gold from parting-plant slimes. Owing to the comparatively high percentages of palladium and platinum, wet methods are used to remove the greater proportion of these metals before electrolytic refining in the Wohlwill cells. THE PLANT The platinum-metals department, Wohlwill room, and gold-melting room extend along the north side of the silver refinery and are separated from the parting plant by a glass partition (Figs. 1 and 2). The platinum-metals department resembles a laboratory built on a large scale, with the various pieces of equipment laid out on terraces to facilitate handling. . Because of the corrosive nature of the solutions, chemical stoneware is used throughout. Elevation of acids is accomplished by means of Mariotte bottles. On the top level are three steam-jacketed stoneware kettles of 50-gal. capacity, also a packed tower. One kettle is used for digesting the slimes while the remaining kettles are used for precipitating the gold. The dissolver is equipped with a treated concrete hood, which is connected to the flue system. Gases are drawn off through the packed tower by means of a 6-in. stoneware exhaust fan. A 15 per cent solution of sodium carbonate is continually circulated through the tower. On the intermediate level are two suction filters, one for removing silver chloride and the other for the gold sand. The filter medium consists of an asbestos pad covered with a filter paper on which is a layer of twill. On the bottom level are two rectangular cementation tanks, 24 by 48 by 24 in. deep, and a suction filter used for removing the platinum-metal concentrates. The circulating pump for the packed tower is also here. Suction is provided by a vacuum pump having a capacity of 8 cu. ft. at 20-in. vacuum.

Jan 1, 1938

As 1970 develops and industrial minerals stand at a crucial point in their progress, research and development programs appear to be the key needed to open up new uses for each mineral's future growth. Radically new processes are needed for making a host of new synthetic products from mineral raw materials which will more nearly meet the demanding specifications required for high performance in space, nuclear and defense applications. Consumer applications for high temperature environments will be needed and are important for continuing the nations economic mineral position. In addition, an acute materials problem limits the effectiveness of some of the newer concepts for controlling ail pollution. What is needed then, according to a report printed by the National Academy of Sciences, is the carefully planned development of a limited number of major centers at universities to provide for both basic research and training of personnel; the nurturing of interdisciplinary mechanisms for research and problem solving within these centers; the achieving of a better balance between physics and chemistry within research, emphasizing the chemical aspects of the material sciences; and the enhancement of a broader professional identity by unifying the various disciplines involved into a possible federation of existing societies which have an interest in the problems. [EE] presents its 1969 annual industrial minerals review, where individual authors evaluate the status of each industrial mineral and recount the major developments which occurred during the year.

Jan 1, 1970

Boundary and general corrosio~z rates for higkpurity alutninum were ~rzeasured irz 16 pct HC1 at sJmllow penetrations (< 25 p). The rates for several high-angle random tilt boundaries, several [001] synzmetrical tilt boundaries, a 54-deg [010] twist, and a 15-deg randorn tw~st boundary were one-fourth to one-third higher than that of the (001) surface used as reference. Boundary attack was slower for 23 and 37-deg [001] tilt boundaries and a 16-deg [010] twist boundary. The corrosion rate for a (111) surface was roughly om-third higher than for (001) and was thus about as high as the corrosion rate of the fastest boundaries. The boundary attack did ?lot appear to parallel the variatiorz of boundavy energy. The signvicance of the anisotropy of corrosion was discussed.

Jan 1, 1966

Two career employees of the US Dept, of the Interior, in a recent study, indicated that by the end of 1974, 73% of all public lands had been entirely or partially closed to exploration and development of essential resources for leasable minerals and 67% had been similarly restricted for locatable minerals.1 This has come about because of the lack of coordination within the executive branch and between the executive and legislative branches of the federal government and without regard for the cumulative, depressing effect on future domestic mineral production. Much of the withdrawn land is felt to have great potential for discovery of significant mineral deposits.

Jan 5, 1976

By H. Tabachnick, N. Hedley

The extraction of gold and silver from ores with alkaline cyanide solutions is well known. Cyanide solutions are also good solvents for many base metal minerals, particularly most of the copper minerals. Leaver and Woolf,1 who determined the solubilities of copper minerals in 0.10 pct sodium cyanide solution, showed that malachite, cuprite, chalcocite, and bornite are readily soluble in cyanide; least soluble are chalcopyrite and chrysocolla. The Mining Chemicals Laboratory of American Cyanamid Co. has studied the possibilities of using cyanide solutions for leaching base metals. In this article the authors present the results of their experiments with cyanide leaching to reduce the copper content of a zinc concentrate from 0.050 pct to the desired specification of less than 0.02 pct. Zinc Ore Sample: The sample of commercial zinc ore used in this investigation to produce zinc concentrates was ball mill feed ranging from 1/2 in. to fines. The ore was crushed to —10 mesh and riffled into 600-g charges for zinc flotation. Analysis revealed 4.54 pct Zn and 0.005 pct Cu. Examined microscopically, the ore consisted essentially of cream-colored sphalerite and carbonate gangue. It contained a small amount of pyrite, partly tarnished. The only copper mineral identified was chalcopyrite, mostly smaller than 20µ, some of which occurred as attachments on sphalerite. Flotation Procedure: Batches of zinc concentrates were made as required according to the following general procedure. A 600-g charge of —10 mesh ore was ground for 4 min at 60 pct solids in a laboratory steel rod mill. Screen sizing showed it to be all —35 mesh with 42 pct —200 mesh. The pulp was transferred to a Fagergren laboratory flotation machine, diluted to 25 pct solids and conditioned for 5 min with 0.6 lb per ton CuSO4, . -5H2O. It was then conditioned with 0.10 lb per ton Sodium Aerofloat promoter and floated for 5 min with pine oil as frother and creosote as froth stiff-ener. The pH during flotation was 8.5. A typical analysis of zinc concentrate subjected to leaching is 44.41 pct Zn and 0.051 pct Cu. The ratio of concentration was close to 10 to 1. Leaching Procedure: Aero Brand cyanide, technical calcium cyanide analyzing 49.5 pet NaCN equivalent, was used for all cyanide leaching tests. For each test three rougher concentrates floated as described were combined (total weight close to 180 g) and the water content adjusted to 150 ml. The percent solids in the pulp was thus 55. After a weighed amount of cyanide flakes had been added, the pulp was agitated on rolls for a given period, then filtered and washed. Filtrate and washed concentrate were assayed for copper content. The procedure for ammonia leaching was similar to the cyanide process. A series of tests was run in which the effects of ammonia as a solvent for copper in the zinc rougher concentrate were investigated. In each test 180 g of zinc rougher concentrate was leached with 150 ml of ammonia solution. Various strengths of ammonia and times of leaching were investigated. The results are shown in Table I. It is apparent that ammonia was a poor solvent for copper in the zinc concentrate; 60 min of agitation with a relatively strong NH:, solution extracted only 2 pct of the copper. CYANIDE LEACHING TESTS Effect of Solution Strength: The solvent effects of 0.125, 0.187, and 0.250 pct NaCN equivalent solutions were compared for leaching periods of 15 min. Residue and filtrate were assayed for copper content. The copper content of the filtrate plus wash was calculated back to the original volume of cyanide solution (150 ml). The effects of cyanide strength are given in Table II, It will be noted that 15 min leaching with 0.25 pct NaCN equivalent solution extracted 74.6 pct of the copper in the zinc concentrate. The leached product assayed 0.013 pct Cu, appreciably below the required specification of 0.020 pct. Effect of Leaching Time: Portions of zinc concentrate were leached with 0.25 pct NaCN equivalent

Jan 1, 1961

Jan 1, 1930

By H. A. J. Wilkens, H. B. C. Nitze

From time to time papers treating of specific cases of Southern gold-mines and mining have appeared in the Transactions of this Institute, as well as in other journals and publications. Mr. George I?. Becker, of the United States Geological Survey, made a reconnaissance of the Southern Appalachian gold-belt during the fall of 1894; the results of his investigations are published under the title of "A Reconnoissance of the GoldFields of the Southern Appalachians," in the Sixteenth Annual Report of the Director of the United States Geological Survey, 1894-95 : Part III., " Mineral Resources of the United States." Mr. Becker has treated the subject mainly in a scientific geological manner. We present this paper to the members of the Institute as requested by the Secretary last May, with the object of covering the ground from a more practical and technical standpoint. The notes for this paper were made in a large measure from personal observations, gained chiefly during the past summer on a trip through the field. In connection with this trip we collected a suite of typical hand-specimens, representing the gold-ores and wall-rock from the more important localities. This collection forms a part of the exhibit

Jan 1, 1896

By W. H. Bassett

Beads of metal frequently appear at the ends of cast-copper wire bars and on the sides of wedge cakes near the top. These are richer in cuprous-oxide than the rest of the casting. A micrographical study of these exudations has been made. It is suggested that the material is forced through the surface while the copper is solidifying. If not eliminated in process of manufacture, it shows on the finished polished sheet copper in patches differing in color from the main body of the sheet. FIGURES 1 to 4 show the copper exudations, at different magnifications, as they appear on the ends of cast wire bars, and on the sides, usually near the top, of wedge cakes. Sometimes the exudations are in fine "drops;" at other times, large masses of the material are found. Microscopic examination of the copper exudation indicates that it is high in oxide and of eutectic proportions. Because of the difficulty of securing a suitable sample, the protuberances have not been analyzed chemically; but the spectroscope shows no indication that there are any more metallic impurities present than in the balance of the copper. The lowest copper plus silver content of the coppers studied for this? paper was 99.914 per cent.; the highest, 99.966 per cent.; so the oxygen content of the whole casting would be well under 0.07 per cent.

Jan 2, 1926

By N. M. Langdon

ON account of its greater economy and cleanliness, and the extent to which iuferior fuels can be utilized for its generation, there has been of late a rapidly increasing tendency to substitute gaseous for solid fuel for metallurgical and other industrial purposes, which has led to various improvements both in the process and apparatus for its manufacture, notably among which may IN mentioned the Tessie Gas Producer* described by Mr. A. L. Holley. A considerable experience by the author with producers of various kinds using anthracite fuel, in connection with the Taylor ore-roast ing furnace at Chester, N. J., with more or less unsatisfactory resnlts, finally led to the erection of the experimental producer described below, which combines in its construction, simplicity, dorability, and accessibility for cleaning and removing the ash and manipulating the fuel. It is adapted to the use of various kinds of fuel, and is capa ble of generating a steady and uniform supply of gas at a minimum cost. It has been in constant use day and night for about five months, and has given very satisfactory results. The producer, as shown in the accompanying sketch, consists of a cylindrieal furnace, preferably inclosed in an iron jacket or casing, having a bosh or inverted cone-shaped base as in a blast furnace. It is provided with a bell and hopper, the bell being hung to a forked lever, and having guide flanges to prevent it from swing ing, and an opening at its apex through which to insert a bar for manipulating the fuel, which when not in use is closed with a plug or stopper. Cleaning is effected through two small doors placed opposite each other at the hearth level, which in order to facilitate the operation is elevated above the floor. The doors are removable, and when closed are by their own weight and by means of bevelled lugs held tightly against their frames, forming a practically tight joint. A blast of commingled steam and air is injected into the fuel through a series of tuyeres underneath the bosh communicating with steam jet injectors. A small flue also connects the door

Jan 1, 1884

C. Q. Payne, New York City: Prof. Blake&apos;s inference that magnetic separation may be successfully employed upon smithsonite and iron oxide, after a preliminary roasting, is confirmed by the fact that this separation has been carried on with entire success for over a year at the works of the Wythe Lead and Zinc Mine Co., Austinville, Va. The ore mined on this property is a mixture consisting chiefly of galenite, smithsonite and limonite. The crude material is crushed, screened and washed in log washers for the removal of clay, and then jigged for the separation of the galenite. The zinc-and iron-ores are then roasted in reverberatory furnaces, being turned and moved towards the bridge-end of the hearth by manual labor. The roasted material contains from 20 to 26 per cent. of metallic iron. The slight difference in the specific gravities and the friable condition of the ores after roasting prevent the separation of the oxides by means of jigging. It was therefore the practice, previous to the use of magnetic separation, to charge the roasted material directly into the retorts of the zinc-furnaces. The rapid cutting of the retorts under this practice proved a serious inconvenience and expense. In the spring of 1892, the writer built for the Wythe Lead and Zino Mine Co. a magnetic separator which embodied several novel features and which was designed to treat the roasted zinc- and ironoxides. This separator has proved entirely successful for the purpose for which it was designed. During the first nine months of its operation, 1415 tons of 2240 pounds of roasted material were passed through the separator, producing about 675 tons of heads carrying from 50 to 55 per cent, of metallic iron, which are sold to a neighboring blast-furnace. The tailings, which contain the zinc, carry from 4 to 6 per cent. of metallic iron. For magnetizing the iron-ore previous to separating it from the zinc-ore, no change whatever mas made in the form of the reverberatory furnace previously employed. It was found that, by charging near the bridge-end of the hearth, toward the end of the roast-

Jan 1, 1894

By J. A. Musselman, P. F. Gnirk

A study was made of indexed penetrations by a single dull bit tooth under statically applied loads into rock subjected to confining pressures from atmospheric to 5,000 p.si and atmospheric pore pressure. Experimental results obtained with a 45" wedge tooth over the above range of pressures are presented for two limestones and a sandstone, a variely of indexing distances and two degrees of tooth dullness. The optimum distance between successive bit-tooth penetrations required for maximum rock damage and chip formation decreases substantially with increa.sing confining pressure above the brittle-to-ductile transition pressure of a particular rock. However, the distance remains approximately constant for a variation in confining pressure below the transition pressure. At a given confining pressure, the bit-tooth force required lor chip formation is constant for indexing distances greater than optimum, but generally decreases linearly with decreasing indexing distance for distances less than optimum. The chip-formation force data obtained at confining pressures for which the chip-generation mechanism is macroscopic-ally of a pseudoplastic nature compare favorably with previous theoretical results for indexed dull hit-tooth penetrntion into an idealized, rigid, perfectly plastic rock. INTRODUCTION To study the cutting action of a roller-cone bit, the interaction of a penetrating bit tooth with craters formed in a rock surfacc by the passage of previous bit teeth must be considered. Current knowledge of the basic mechanics of bit tooth-rock intcract:on under simulated borehole environmental conditions has been extensively reviewed.&apos;,&apos; Particularly of current interest are the effects of bit-tooth shape, distance between successive penetrations and differential pressure at the rock surface on the extent of the interaction. Pertinent to this paper are results of an experimental investigationb f the interaction between successive penetrations by sharp, wedge-shaped bit teeth. It was demonstrated that both bit-tooth angle and differential pressure influence the extent of rock damage between successive bit-tooth penetrations. Specifically, the optimum or minimum distance between successive penetrations required for maximum interact&apos;on or chip generation tends to decrease with decreasing bit-tooth angle and increasing differential pressure. In addition, at differential pressures on the order of 2,000 psi for four va- rieties of limestones and sandstones, the macroscopic mechanism of chip formation exhibits a transition from brittle to ductile. In this paper, experimental consideration is given to successive or indexed penetrat ons by wedge-shaped bit teeth. Since pore pressure in a rock sample is maintained at atmospheric pressure, the differential pressure at the fluid-rock interface is equal to the confining pressure. The degrees of bit-tooth dullness include teeth with flat and round apexes (Fig. 1). Of primary concern in this paper are the bit-tooth forces required for chip formation, the macroscopic mechanism of chip formation and the minimum distance between successive penetrations, i.e., optimum indexing distance required for maximum rock damage, as functions of differential pressure. Of further interest is a comparison of actual bit-tooth chip formation forces at elevated differential pressures with calculated forces from previous theoretical results4 for indexed dull bit tooth penetration into a rigid-plastic rock. EXPERIMENTAL APPARATUS AND PROCEDURE The experimental apparatus consists of a pressure vessel equipped with a piston through the side of the vessel (Fig. 2). A single bit tooth inserted in the lower end of the piston is forced at a desired rate into the rock when the ram pressure chamber is pressurized. Electrical instrumentation incorporated into the apparatus yields a graphical plot of force on the piston as a function of bit-tooth penetration or displacement into the rock. Since the piston and ram assembly are in force equilibrium for a constant confining pressure in the main vessel, the fluid volume in the vessel remains constant during bit-tooth penetration. Hence, the force resisting penetration of the tooth is independent of the force exerted on either end of the as-