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Jan 1, 1940

Report of the Secretary TO THE BOARD OF DIRECTORS AND THE MEMBERS OF THE AMERICAN INSTI¬TUTE OF MINING AND METALLURGICAL ENGINEERS GENTLEMEN As will be shown by the special reports of the Finance, Membership, Library, Papers and Publications, Increase of Membership, and other standing Committees, together with that of the Treasurer, the year 1927 was one in which the Institute made very satisfactory progress in a number of directions. In total numbers the membership is no larger but in revenue from dues there has been a marked increase. This has been due to the promotion to full membership of Junior Associates of earlier years, to the larger proportion that come in originally as members rather than juniors, and to the keener interest in the work of the Institute reflected in prompter payment of dues. The latter is important, since experience shows that of those who fall behind a large number must ultimately be dropped for non-payment. Conditions in the mining in¬dustries have been healthy though not booming. It has been much easier for members to find employment and meet their financial obligations but there has not been that flow of young men into mining, and hence in part into the Institute, that characterized certain earlier years. Rather the tendency toward centralization and larger industrial units has re¬stricted the number, though not the scope, of opportunities for technical men in the mineral industries. The Institute is constantly receiving resignations from members crowded out of mining into other lines of activity. On the other hand, those who remain in mining and metal¬lurgy have a greatly increased necessity for information and contacts with technology. A few years ago many superintendents and most foremen were non-technical men. Today the reverse rule obtains and shift bosses and men who occupy even lower positions in industrial units are called upon to know and to apply such an amount of technical knowl¬edge that graduate engineers are the rule rather than the exception. The curious situation has obtained that with a much smaller enrollment of students in the schools of mining and metallurgy there has been at times an actual shortage of young engineers for beginners' jobs. The young men retort that the conditions of employment and pay offered in mining are not equal to those in other lines and, while it is undoubtedly true that the young engineer beginning in mining is able to start under conditions markedly better as to pay, living, and responsibility than did the men who are now leaders, they are required to know much more and have usually spent more in time and money to qualify for their jobs. The whole matter is one which warrants much more attention than has been given to it. For the Institute it is important since the young men

Jan 1, 1923

By V. J. Decarlo, J. J. Gilman

POLISHING pure zinc differs somewhat from polishing less reactive metals. The problem is not that of finding a suitable reagent, but rather of producing the polish in such a way that the surface remains polished after it is removed from the polishing bath. In other words., the anodic film that is vital to the polishing mechanism' must be tightly adherent and nonporous. It is usually desirable that it be thin. Polishing solutions consist of proper proportions of an acid and a strong oxidizing agent. In electro-polishing, the external circuit acts as the oxidizing agent. The proportions are critical because the essential surface film must be maintained at approximately constant thickness during the polishing process. In the case of zinc, chiefly two oxidizing agents, chromic and nitric acids, have been used. The simplest polishing reagent is concentrated nitric acid. However, it has certain disadvantages. It tends to pit: an excessive amount of heat is evolved during polishing; and the oxide film that it produces is not very stable, so that the polished sur-

Jan 1, 1957

By H. Brevers, Maurice Rey

Through circumstances connected with the war, the senior author lost his records, therefore it has been impossible to include numerical data in this paper. The arsenical quicksilver ore investigated had been roasted, with poor metallurgical results. The vapor-tension temperature curves of mercury and arsenious trioxide are similar, and the arsenical compound hampers the coalescence of mercury drops in the condenser and is the cause of large stack losses. The ore was a gray limestone carrying small amounts of carbon and mineralized with cinnabar and two arsenic minerals, realgar (As2S2) and arsenopyrite (FeAsS). The proportion of realgar often exceeded that of cinnabar; the proportion of arsenopyrite was smaller. The grade of the ore varied between 0.8 and 4 per cent Hg. The problem was to make a high-grade mercury concentrate, as free from arsenic as possible. The water used throughout the testing was hard, having a pH of about 8. Flotation of Realgar Realgar showed a very strong tendency to float. It formed a film at the surface of the pulp and floated in abundance with only pine oil. Therefore an attempt was made to float the realgar before the cinnabar, but this was not very successful; the percentage of mercury in the realgar concentrate could never be brought below 2 or 3 per cent. Cinnabar slimed easily and floated with pine oil, so that some of it always accompanied the realgar. There was also the question of the cinnabar-arseno-pyrite separation. On further investigation it was found that realgar can be floated not only with pine oil but even better with a combination of hydrocarbons and pine oil. Washing the ore with ether revealed that it contained hydrocarbons, which helped to float the realgar. In this connection it belongs to the same class as carbon, sulphur and talc. It can be floated also with a xanthate, when activated by a heavy-metal salt. The conditions favoring the two types of flotation are opposed, as activation by a copper salt facilitates xanthate flotation (in fact, is even necessary to it), whereas it hinders pine oil and petroleum flotation. One type of flotation can be termed non-polar and the other polar, a distinction that has been stressed in a previous paper.' Depression of Realgar and Flotation of Cinnabar Many chemicals were tested in an attempt to float the cinnabar and depress the realgar. Finally starch rendered soluble with caustic soda was tried, also several grades of commercial soluble starch, and dextrin was found to be the best and the most convenient reagent. Several of these starch preparations have a strong flocculating effect on the pulp, which is a distinct disadvantage. Dextrin, with its low flocculating power, is excellent. It is noteworthy that starch preparations are also depressants for carbon and talc, so that the fact apparently has a general

Jan 1, 1943

By Maurice Rey, H. Brevers

Through circumstances connected with the war, the senior author lost his records, therefore it has been impossible to include numerical data in this paper. The arsenical quicksilver ore investigated had been roasted, with poor metallurgical results. The vapor-tension temperature curves of mercury and arsenious trioxide are similar, and the arsenical compound hampers the coalescence of mercury drops in the condenser and is the cause of large stack losses. The ore was a gray limestone carrying small amounts of carbon and mineralized with cinnabar and two arsenic minerals, realgar (As2S2) and arsenopyrite (FeAsS). The proportion of realgar often exceeded that of cinnabar; the proportion of arsenopyrite was smaller. The grade of the ore varied between 0.8 and 4 per cent Hg. The problem was to make a high-grade mercury concentrate, as free from arsenic as possible. The water used throughout the testing was hard, having a pH of about 8. Flotation of Realgar Realgar showed a very strong tendency to float. It formed a film at the surface of the pulp and floated in abundance with only pine oil. Therefore an attempt was made to float the realgar before the cinnabar, but this was not very successful; the percentage of mercury in the realgar concentrate could never be brought below 2 or 3 per cent. Cinnabar slimed easily and floated with pine oil, so that some of it always accompanied the realgar. There was also the question of the cinnabar-arseno-pyrite separation. On further investigation it was found that realgar can be floated not only with pine oil but even better with a combination of hydrocarbons and pine oil. Washing the ore with ether revealed that it contained hydrocarbons, which helped to float the realgar. In this connection it belongs to the same class as carbon, sulphur and talc. It can be floated also with a xanthate, when activated by a heavy-metal salt. The conditions favoring the two types of flotation are opposed, as activation by a copper salt facilitates xanthate flotation (in fact, is even necessary to it), whereas it hinders pine oil and petroleum flotation. One type of flotation can be termed non-polar and the other polar, a distinction that has been stressed in a previous paper.' Depression of Realgar and Flotation of Cinnabar Many chemicals were tested in an attempt to float the cinnabar and depress the realgar. Finally starch rendered soluble with caustic soda was tried, also several grades of commercial soluble starch, and dextrin was found to be the best and the most convenient reagent. Several of these starch preparations have a strong flocculating effect on the pulp, which is a distinct disadvantage. Dextrin, with its low flocculating power, is excellent. It is noteworthy that starch preparations are also depressants for carbon and talc, so that the fact apparently has a general

Jan 1, 1943

By Benjamin N. Webber

The peninsula of Nicoya contains virtually all of the known manganese deposits of Costa Rica. These are south and west of the Tempisque River, which flows across the peninsula near its juncture with the mainland. This peninsula forms the westernmost part of the province of Guana-caste, which is the northern. of the two Pacific Coast provinces of Costa Rica. The larger villages are connected by ox-cart roads and trails. The area may be covered on horseback without difficulty except during the rainy season, when rivers are in flood and difficult to ford. This is particularly true of the Rio Seco-Guay-jiniquil area, where there are no inhabitants and few open trails through the tropical jungle. Santa Cruz and Sardinal are served by the Taca Airlines, two planes a week from San Jose and Puntarenas. The port of Puntarenas has excellent loading facilities but none are available nearer the manganese districts; there ore must be lightered to vessels standing offshore. Physiography In Costa Rica there are three physiographic divisions: (I) the central plateau (Mesa Central), a somewhat dissected lava platform upon which are superimposed volcanic peaks, some of which are still active; (2) the Atlantic lowlands and (3) the Pacific lowlands. The peninsula of Nicoya and the larger part of the province of Guanacaste lie within the Pacific low- lands. The term "lowland" indicates relation to the central plateau, as the peninsula of Nicoya is largely mountainous. The mountains of Nicoya form the southern extremity of a range of low hills, which are almost continuous along the Costa Rican coast to the Nicaraguan border. The coast line shows evidence of subsidence. The Gulf of Nicoya obviously is the drowned valley of the Tempisque River. The west coast of Nicoya shows many rocks, shoals, bays, inlets and small islands as evidence of a sea encroachment. The altitude of the manganese deposits ranges from 0 to 800 ft. Topography is of the mature type of wide valleys and low hills, often with abrupt slopes. The climate is tropical and humid; rainfall of 125 in. falls largely between Sept. I and Jan. I. Vegetation often is very dense, the Rio Seco-Guayjiniquil area being truly tropical jungle, containing many hardwoods. History and Production The production of manganese ore in Costa Rica apparently dates from the first World War. It reached a peak of about 10,000 tons in the year 1919, then declined rapidly. Evidence of this period of prospecting has rotted away or been swallowed by the jungle. The war now in progress apparently revived the interest in Costa Rican manganese and has encouraged further prospecting. Deposits long known have been redenounced and trails have been cut through the jungle to them. Many new deposits have been discovered in the last

Jan 1, 1949

By Benjamin N. Webber

The peninsula of Nicoya contains virtually all of the known manganese deposits of Costa Rica. These are south and west of the Tempisque River, which flows across the peninsula near its juncture with the mainland. This peninsula forms the westernmost part of the province of Guana-caste, which is the northern. of the two Pacific Coast provinces of Costa Rica. The larger villages are connected by ox-cart roads and trails. The area may be covered on horseback without difficulty except during the rainy season, when rivers are in flood and difficult to ford. This is particularly true of the Rio Seco-Guay-jiniquil area, where there are no inhabitants and few open trails through the tropical jungle. Santa Cruz and Sardinal are served by the Taca Airlines, two planes a week from San Jose and Puntarenas. The port of Puntarenas has excellent loading facilities but none are available nearer the manganese districts; there ore must be lightered to vessels standing offshore. Physiography In Costa Rica there are three physiographic divisions: (I) the central plateau (Mesa Central), a somewhat dissected lava platform upon which are superimposed volcanic peaks, some of which are still active; (2) the Atlantic lowlands and (3) the Pacific lowlands. The peninsula of Nicoya and the larger part of the province of Guanacaste lie within the Pacific low- lands. The term "lowland" indicates relation to the central plateau, as the peninsula of Nicoya is largely mountainous. The mountains of Nicoya form the southern extremity of a range of low hills, which are almost continuous along the Costa Rican coast to the Nicaraguan border. The coast line shows evidence of subsidence. The Gulf of Nicoya obviously is the drowned valley of the Tempisque River. The west coast of Nicoya shows many rocks, shoals, bays, inlets and small islands as evidence of a sea encroachment. The altitude of the manganese deposits ranges from 0 to 800 ft. Topography is of the mature type of wide valleys and low hills, often with abrupt slopes. The climate is tropical and humid; rainfall of 125 in. falls largely between Sept. I and Jan. I. Vegetation often is very dense, the Rio Seco-Guayjiniquil area being truly tropical jungle, containing many hardwoods. History and Production The production of manganese ore in Costa Rica apparently dates from the first World War. It reached a peak of about 10,000 tons in the year 1919, then declined rapidly. Evidence of this period of prospecting has rotted away or been swallowed by the jungle. The war now in progress apparently revived the interest in Costa Rican manganese and has encouraged further prospecting. Deposits long known have been redenounced and trails have been cut through the jungle to them. Many new deposits have been discovered in the last

Jan 1, 1949

By J. B. NEALEY

MANY nonferrous smelting plants have recently adopted natural gas as fuel with resultant economies, both in cost and efficiency of utilization. Not only has this fuel been used for roasting, reduction, sintering, drossing, and smelting, but also for power. All of the three big smelters near Salt Lake City, Utah, have been changed over from coal and oil firing to gas. Among these is the plant of the International Smelting Co., Tooele, an Anaconda subsidiary, smelters of both copper and lead ores. In the roasting division at Tooele are 32 MacDougall six-hearth roasters, each 16 ft. in diameter and 19 ft. high. Two gas burners are installed on each furnace. These burners are of the single-valve, automatic gas-air proportioning type using high-pressure gas at 10 lb.

Jan 1, 1933

By Maurice Rey, H. Brevers

THROUGH circumstances connected with the war, the senior author lost his records therefore it has been impossible to include numerical data in this paper. The arsenical quicksilver ore investigated had been roasted, with poor metallurgical results. The vapor-tension temperature curves of mercury and arsenious trioxide are similar, and the arsenical compound hampers the coalescence of mercury drops in the condenser and is the cause of large stack losses. The ore was a gray limestone carrying small amounts of carbon and mineralized with cinnabar and two arsenic minerals, realgar (As2S2) and arsenopyrite (FeAsS). The proportion of realgar often exceeded that of cinnabar; the proportion of arsenopyrite was smaller. The grade of the ore varied between 0.8 and 4 per cent Hg. The problem was to make a high-grade mercury concentrate, as free from arsenic as possible. The water used throughout the testing was hard, having a pH- of about 8. FLOTATION OF REALGAR Realgar showed a very strong tendency to float. It formed a film at the surface of the pulp and floated in abundance with only pine oil. Therefore an attempt was made to float the realgar before the cinnabar, but this was not very successful; the percentage of mercury in the realgar concentrate could never be brought below 2 or 3 per cent. Cinnabar slimed easily and floated with pine oil, so that some of it always accompanied the realgar. There was also the question of the cinnabar-arsenopyrite separation. On further investigation it was found that realgar can be floated not only with pine oil but even better with a combination of hydrocarbons and pine oil. Washing the ore with ether revealed that it contained hydrocarbons, which helped to float the realgar. In this connection it belongs to the same class as carbon, sulphur and talc. It can be floated also with a xanthate, when activated by a heavy-metal salt. The conditions favoring the two types of flotation are opposed, as activation by a copper salt facilitates xanthate flotation (in fact, is even necessary to it), whereas it hinders pine oil and petroleum flotation. One type of flotation can be termed nonpolar and the other polar, a distinction that has been stressed in a previous paper. DEPRESSION OF REALGAR AND FLOTATION OF CINNABAR Many chemicals were tested in an attempt to float the cinnabar and depress the realgar. Finally starch rendered soluble with caustic soda was tried, also several grades of commercial soluble starch, and dextrin was found to be the best and the most convenient reagent. Several of these starch preparations have a strong flocculating effect on the pulp, which is a distinct disadvantage. Dextrin, with its low flocculating power, is excellent. It is noteworthy that starch preparations are also depressants for carbon and talc, so that the fact apparently has a general

Jan 1, 1941

By C. G. Southmayd

Anyone who has been confronted with the problem of predicting the performance of a sand-pump installation is vitally aware of the dearth of precise information that has been published on this important subject. Such data as have been collected are not readily available in a concise and readily usable form, so that many operators would find it a considerable chore to find the pertinent information required to undertake a detailed study. The purpose of this paper is to assemble such established data, correlate them with field experience and outline the factors that must be appraised in the determination of a satisfactory pump installation. The transportation of solids in solution is of vital interest to every mill superintendent and operator, and many of the factors that are involved in this hydraulic problem vary widely from installation to installation, and in some cases even from time to time on any one installation. These include: type of solids (including shape of particles), size of solids (grind), percentages of fines (slimes), dilution of pulp, contour of pipe line, type of pipe, age of pipe line, effect that diameter of pipe has on characteristic flow conditions, and other factors. Some of these have been fairly well determined by experimental work but many still must be established through interpolating or extrapolating between values that have been derived from known field conditions. Most problems primarily concern the transportation of a definite weight of dry solids from one specific location to another. The type of material, shape of particles, grind and percentages of fines are established and very often the dilution at which the solids must be handled as well. The problem then evolves into a determination of the size, type and contour of the pipe line and the net effective head against which the pump must operate. Before discussing the determination of the head, it might be well to review the interrelationship between the pump discharge (capacity), the head developed by the pump and the pump speed, which will apply to any centrifugal pump installation. Effect of Pump Speed Basically, the head developed by a centrifugal pump varies as the square of the pump speed and the discharge as the first power of the speed. However, even at constant speed a centrifugal pump will operate over a wide range of capacities, depending upon the head that must be developed to deliver the liquid or pulp to the end of the pipe line. This is shown graphically in Fig. I. If the pump in question is being driven at a constant speed of goo r.p.m. it will deliver 500 U. S. gal. per min. against a head of 56 ft., 800 U. S. gal. per min. against a head of 50 ft., and so on. In other words, at this speed the capacity of the pump will be determined and limited by

Jan 1, 1947

By C. G. Southmayd

Anyone who has been confronted with the problem of predicting the performance of a sand-pump installation is vitally aware of the dearth of precise information that has been published on this important subject. Such data as have been collected are not readily available in a concise and readily usable form, so that many operators would find it a considerable chore to find the pertinent information required to undertake a detailed study. The purpose of this paper is to assemble such established data, correlate them with field experience and outline the factors that must be appraised in the determination of a satisfactory pump installation. The transportation of solids in solution is of vital interest to every mill superintendent and operator, and many of the factors that are involved in this hydraulic problem vary widely from installation to installation, and in some cases even from time to time on any one installation. These include: type of solids (including shape of particles), size of solids (grind), percentages of fines (slimes), dilution of pulp, contour of pipe line, type of pipe, age of pipe line, effect that diameter of pipe has on characteristic flow conditions, and other factors. Some of these have been fairly well determined by experimental work but many still must be established through interpolating or extrapolating between values that have been derived from known field conditions. Most problems primarily concern the transportation of a definite weight of dry solids from one specific location to another. The type of material, shape of particles, grind and percentages of fines are established and very often the dilution at which the solids must be handled as well. The problem then evolves into a determination of the size, type and contour of the pipe line and the net effective head against which the pump must operate. Before discussing the determination of the head, it might be well to review the interrelationship between the pump discharge (capacity), the head developed by the pump and the pump speed, which will apply to any centrifugal pump installation. Effect of Pump Speed Basically, the head developed by a centrifugal pump varies as the square of the pump speed and the discharge as the first power of the speed. However, even at constant speed a centrifugal pump will operate over a wide range of capacities, depending upon the head that must be developed to deliver the liquid or pulp to the end of the pipe line. This is shown graphically in Fig. I. If the pump in question is being driven at a constant speed of goo r.p.m. it will deliver 500 U. S. gal. per min. against a head of 56 ft., 800 U. S. gal. per min. against a head of 50 ft., and so on. In other words, at this speed the capacity of the pump will be determined and limited by

Jan 1, 1947

By C. G. Southmayd

ANYONE who has been confronted with the problem of predicting the performance of a sand-pump installation is vitally aware of the dearth of precise information that has been published on this important subject. Such data as have been collected are not readily available in a concise and readily usable form, so that many operators would find it a considerable chore to find the pertinent information required to undertake a detailed study. The purpose of this paper is to assemble such established data, correlate them with field experience and outline the factors that must be appraised in the determination of a satisfactory pump installation. The transportation of solids in solution is of vital interest to every mill superintendent and operator, and many of the factors that are involved in this hydraulic problem vary widely from installation to installation, and in some cases even from time to time on any one installation.. These include: type of solids (including shape of particles), size of solids (grind), percentages of fines (slimes), dilution of pulp, contour of pipe line, type of pipe, age of pipe line, effect that diameter of pipe has on characteristic flow conditions, and other factors. Some of these have been fairly well determined by experimental work but many still must be established through interpolating or extrapolating between values that have been derived from known field conditions. Most problems primarily concern the transportation of a definite weight of dry solids from one specific location to another. The type of material, shape of particles, grind and percentages of fines are established and very often the dilution at which the solids must be handled as well. The problem then evolves into a determination of the size, type and contour of the pipe line and the net effective head against which the pump must operate. Before discussing the determination of the head, it might be well to review the interrelationship between the pump discharge (capacity), the head developed by the pump and the pump speed, which will apply to any centrifugal pump installation. EFFECT OF PUMP SPEED Basically, the head developed by a centrifugal pump varies as the square of the pump speed and the discharge as the first power of the speed. However, even at constant speed a centrifugal pump will operate over a wide range of capacities, depending upon the head that must be developed to deliver the liquid or pulp to the end of the pipe line. This is shown graphically in Fig. I. If the pump in question is being driven at a constant speed of 900 r.p.m. it will deliver 500 U. S. gal. per min. against a head of 56 ft., 800 U. S. gal. per min. against a head of 50 ft., and so on. In other words, at this speed the capacity of the pump will be determined and limited by

Jan 1, 1946

By D. S. Sanders, E. W. Witcomb

FLOTATION tests, from which the flowsheet for the concentrator was determined, were made in a pilot mill at Chuquicamata and later comparative testing of full size flotation cells was done at the Andes Copper Mining Co. concentrator in Potrerillos. The principal sulphide copper mineral is chalcocite with varying amounts of covellite, enargite, and chalcopyrite. The oxidized portion is principally antlerite, a green basic copper sulphate. The gangue minerals include quartz, sericite, pyrite, feldspars and kaolin. Chuquicamata pit ores have proved to be hard grinding. The results of the flotation and metallurgical work prove that good extraction and concentrate grade can be obtained under a rather wide range of conditions. Metallurgy In general the metallurgy of the ore requires a fairly close control of the grind to the primary rougher flotation and of the regrind of the primary rougher concentrate before cleaning. Regrinding is necessary to reduce the insoluble content of the final concentrate since a large part of the middling combinations are between the copper and silica minerals. The alkalinity of the pulps can vary between wide limits and control of the percent solids gives the desired grind. Alkalinity Control Arroyo Salado water is supplied to the concentrator head tanks. It contains about 5000 ppm of salts but test work shows no deleterious effect. Actually this water permits a decrease of as much as 1 lb of lime per ton of ore as compared to San Pedro water, which is used for leaching oxide ore. About one quarter of the water flow through the concentrator will be new water from the reservoir. The remainder will be reclaimed from the thickeners. For primary grinding and rougher flotation, new and reclaimed water are combined in the head tanks. To avoid erratic results, only new water is used in the regrind system. Milk of lime is added to the rod mill feed chute to obtain the maximum benefit of mixing with the ore. This protects the equipment from corrosion due to entrained acids and soluble copper salts. Lime consumption is 3 to 5 lb per ton of ore. Grinding and Flotation The six bin gates over each belt feeder are opened in controlled combination and sequence to keep a live bed of ore in the bin to prevent arching and to obtain mixing. The milk of lime added ahead of the rod mill is regulated to suit rougher flotation requirements. The primary promoter reagent, Aerofloat 238, is added to the 10-mesh discharge of the rod mill as it is laundered to the ball mill scoop box. The classifier overflow is regulated to produce a grind of about 12 to 15 pct +65 mesh and 60 pct -200 mesh. A secondary promoter Z-4 (aml zanthate) and the pine oil frother are added in the overflow launder where a pH of 10 to 11 is maintained. Comparatively heavy beds of froth on the

Jan 1, 1952

By Walter R. Hibbard, Walter L. Finlay

INTRODUCTION THE key feature of the lattice coherency theory of precipitation hardening1-6 is the forced coherence between matrix and precipitate which elastically strains both lattices and is believed to be the major source of strengthening in precipitation hardening. In systems exhibiting age hardening, the atom movements leading to precipitation are not at all extensive and are such as to require the minimum amount of energy to produce the interface; that is, the new lattice forms in such a way as to be as nearly as possible a continuation of the old with a matched, coherent plane at the interface at least during the initiation of the precipitation. The crystallographic sequence whereby regions of the matrix change to the precipitate lattice usually can be resolved into a set of shearing operations.5,6 Conversely, the perhaps novel speculation is made that solution of a second phase is accompanied by shearing movements which are possibly the reverse of the precipitation shearing movements. A basic premise of the investigation reported in this paper is that precipitation and solution shearing movements constitute structural weaknesses which might cooperate with applied stresses to facilitate plastic deformation. Another basic premise of the investigation is that the application of hydrostatic pressure to a precipitation hardening system will significantly alter the degree of disregistry across the matrix-precipitate interface and thereby significantly affect the course of age hardening. Two binary precipitation hardening systems were investigated: 12 pct zinc in aluminum which undergoes transformations, both precipitation and solution, by a simple crystallographic mechanism; and 4 pct copper in aluminum which undergoes a complex transformation in precipitating and dissolving a second phase. The effects of the application of uniaxial tensile creep stress during elevated temperature aging of both systems and of hydrostatic pressure during the elevated temperature aging of 12 pct aluminum-zinc were then investigated. Previous Investigations Van Wert in 1935,7 studied the effect of hydrostatic pressure on the room temperature age hardening of a few precipitation hardening systems. The latter were rather unfortunately selected since none is known to exhibit any marked volume change on aging and the majority were complex commercial alloys the precipitation mechanisms of which are not known. Jenkins, Bucknall and Jenkinson,8 in 1944, applied tensile creep stresses to a complex coppernickel-silicon alloy at various temperatures. The complexity of the alloy and the industrial objective of the work did not permit an appreciable addition to the theoretical understanding of either deformation or precipitation hardening.

Jan 1, 1948

By Maurice Rey, H. Beavers

THROUGH circumstances connected with the war, the senior author lost his records, therefore it has been impossible to include numerical data in this paper. The arsenical quicksilver ore investigated had been roasted, with poor metallurgical results. The vapor-tension temperature curves of mercury and arsenious trioxide are similar, and the arsenical compound hampers the coalescence of mercury drops in the condenser and is the cause of large stack losses. The ore was a gray limestone carrying small amounts of carbon and mineralized with cinnabar and two arsenic minerals, realgar (As2S2) and arsenopyrite (FeAsS). The proportion of realgar often exceeded that of cinnabar; the proportion of arsenopyrite was smaller. The grade of the ore varied between 0.8 and 4 per cent Hg. The problem was to make a high-grade mercury concentrate, as free from arsenic as possible. The water used throughout the testing was hard, having a pH of about 8. FLOTATION OF REALGAR Realgar showed a very strong tendency to float. It formed a film at the surface of the pulp and floated in abundance with only pine oil. Therefore an attempt was made to float the realgar before the cinnabar, but this was not very successful; the percentage of mercury in the realgar concentrate could never be brought below 2 or 3 per cent. Cinnabar slimed easily and floated with pine oil, so that some of it always accompanied the realgar. There was also the question of the cinnabar-arsenopyrite separation. On further investigation it was found that realgar can be floated not only with pine oil but even better with a combination of hydrocarbons and pine oil. Washing the ore with ether revealed that it contained hydrocarbons, which helped to float the realgar. In this connection it belongs to the same class as carbon, sulphur and talc. It can be floated also with a xanthate, when activated by a heavy-metal salt. The conditions favoring the two types of flotation are opposed, as activation by a copper salt facilitates xanthate flotation (in fact, is even necessary to it), whereas it hinders pine oil and petroleum flotation. One type of flotation can be termed nonpolar and the other polar, a distinction that has been stressed in a previous paper.1 DEPRESSION OF REALGAR AND FLOTATION OF CINNABAR 'Many chemicals were tested in an attempt to float the cinnabar and depress the realgar. Finally starch rendered soluble with caustic soda was tried, also several grades of commercial soluble starch, and dextrin was found to be the best and the most convenient reagent. Several of these starch preparations have a strong flocculating effect on the pulp, which is a distinct disadvantage. Dextrin, with its low flocculating power, is excellent. It is noteworthy that starch preparations are also depressants for carbon and talc, so that the fact apparently has a general

Jan 1, 1941

By John V. Beall

There was optimism on 14th Street on April 22, Earth Day. We only have the report second hand because the demonstration conflicted with another appointment. Fifth Avenue was closed to vehicular traffic from 14th Street to the Park for a few hours and the crowd that showed up to promenade rivaled anything that can be imagined, even one at a country fair in Merry Old England. Certainly the domestic animals were there and the costumes were wild-as they are almost any day on 5th Avenue. However, the mood was friendly, happy and optimistic according to one of our neighbors who filmed and taped interviews with some of the characters. People think the air is going to be clean, and the water pure in the future. Land is going to be treated with respect. Even if the demonstration temporarily fouled the streets with litter, it served the purpose of dramatizing awareness. In talking to our friend about his experiences we didn't miss the opportunity to sound out his impression of whether or not people recognize that no group of people nor industry has a monopoly on pollution.

Jan 1, 1970

By R. B. Gavert, David J. Mack

ROOM- and elevated-temperature compression tests were made on the binary 3/2 electron compounds AuZn, CuAu, AgZn, AgMg, AuCd, and NiA1. These compounds possess either the B2 CsC1-type ordered structure or the A2 bee disordered structure represented commonly as ß and ß on equilibrium phase diagrams. In testing at room temperature, cylindrical specimens 0.508 cm by 0.330 cm diam were seated directly on an instron compression load cell (CF 0 to 10,000 lb). At elevated temperatures, testing included a special apparatus with a furnace heat source and a protective atmosphere.' The specimens were strained at a rate of 1 pet per min. The compounds were prepared from 99.99 pet or better high-purity elements. Vacuum and/or argon cover gas was used throughout the mixing, melting, and specimen drawing processes. The generally equi-axed specimen grains varied in size from 0.5 to 1.5 mm for the five different compounds. The stress-strain curves in compression showed

Jan 1, 1968

By Augustus Locke

THE technical sessions at the Regional Meeting of the A.I.M.E. in San Francisco are to be de- voted LO changes, current or predictable, which may be expected to alter today's practices in mining and metallurgical engineering. Our present condition may be summarized as follows: Capacity to produce is excessive for domestic needs in molybdenum, copper, iron, and oil; sufficient in lead, zinc, and potash; deficient in aluminum, manganese, tungsten, chromium, and tin. Gold and silver are complicated by their use as money. Or, to look at it in another way, the "growth curles" of production, as C. K. Leith emphasizes, characteristically rise slowly at the beginning, show a second stage of rapid growth, and a third stage of leveling off. The third stage is already reached here in coal. copper, iron, lead, and zinc. But still in the second slage are oil, molybdenum, potash, and others.

Jan 1, 1939

By J. McLaren Forbes

Geologists and engineers in charge of diamond drilling often have no practical experience in the work, yet they must direct the drillers. In discussing some of the problems that arise, the author of this paper has tried to remember the things he did not know about diamond drilling when he first came in contact with that work. The basic reason for most diamond-drill holes is to obtain information. The more thorough the understanding of the geological and engineering problems involved, the greater will be the benefit derived from a drilling program. One of the best methods to ensure some thinking before drilling is to record on the permanent drill log, before the hole is collared, the reasons for the work and the information desired from that particular hole. When the hole is finished, the information obtained should be recorded. Driller The choice of a diamond driller is very important. If no experienced driller is available, a competent miner who has a sense of responsibility and better than average mechanical ingenuity can do the work. The best answer to most practical drilling problems, from the standpoint of the person in charge of the drilling program, is the service of experienced diamond drillers or drilling firms. Equipment Drilling equipment should be adequate to put down the longest hole desired and handle the toughest ground encountered. The type of bit used depends upon the ground drilled. Experimenting with various bits and careful study of footage records are the best means of determining which to use. Under ordinary circumstances it is best to drill using an EX barrel when possible. The length of rod and core barrels that can be used depends on the size of the drill station. Also, the length of core barrel depends on the way the ground cores. In good ground as much core will be recovered with a 10-ft. barrel as with a shorter one, and with considerable saving of drilling time. A water pump is needed if the hole is so deep that the water pressure is not strong enough to wash out the cuttings, or if it is drilled at an angle that prevents full force of the water pressure. Instructions For an Inexperienced Driller 1. Never run a bit too long a time. When a bit seems to be "good for one more run," discard it. 2. Always let the rods down on bottom easily. Protect the bit from sudden shock. 3. Start the drilling slowly and easily. Do not put pressure on the bit too fast. Diamonds can break. 4. Be sure the water pressure is strong enough to clear the bit, but do not use more water than is needed, as it may wash away the core. Usually, if no core is recovered the hole is a total loss. 5. When dry-blocking, do not run without water longer than necessary as the bit may burn. 6. Be sure the rods are well caulked and tightly screwed together. If not well caulked they will lose water, and if not

Jan 1, 1946

By AIME

TITANIUM-RICH ilmenite deposits, situated in the Allard Lake area in Quebec some 400 miles down the St. Lawrence River from Quebec City and 28 miles north of Havre St. Pierre on the north shore of the Gulf of St. Lawrence, are undergoing an intensive development program by the joint efforts of the Kennecott Copper Corp. and The New Jersey Zinc Co. Easily accessible ore, amounting to about 125 million long tons and carrying from thirty to forty per cent titanium oxide, has been delimited. Plans are being made for construction of an electric smelter at Sorel, on the south bank of the St. Lawrence midway beween Montreal and Three Rivers, which will produce 650 long tons of high-grade titanium slag and 500 long tons of iron per day from 1500 long tons of ore. Occurrence of ilmenite ore in this area has been known since J. A. Retty reported his geological work in the lower Romaine River area for the Quebec Bureau of Mines in 1941. In this report Dr. Retty mentions the presence of anorthosite rocks, some of which were rich in ilmenite. Claims were staked by several interests but the small showings and complex metallurgy were too formidable for any organization not adequately equipped with capital, metallurgical knowhow, and market outlets. However, Kennecott became interested and through a newly formed Canadian subsidiary, Kennco Explorations Ltd., options were taken up under the direction of A. H. Robertson. An area of 300 square miles was traversed in the summers of 1945 and 1946. During 1946 and 1947 geophysical and diamond-drill prospecting disclosed a num-

Jan 1, 1948