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By E. V. Potter, E. T. Hayes, H. C. Lukens

LARGE volumes of hydrogen are liberated at the cathode during electrolytic precipitation of manganese. Most of the gas escapes from the electrolyte, but a considerable amount may be entrapped in the manganese plate. Gas has been observed to escape from manganese melts in puffs that ignite at the surface. It has been reported that castings made with electrolytic manganese tend to rise in the molds; for this reason the manganese is often treated to remove hydrogen before the melt is made or it is premelted and used as cast manganese in making the alloys. The effect of hydrogen on the properties of manganese and its alloys is not known, but its effect on iron and iron alloys has been studied extensively.1.2 The close relationship between iron and man¬ganese suggests that hydrogen may have a similar effect on the properties of manganese and its alloys. The purpose of this investigation was to determine the amount of hydrogen or other gases in typical commercial electrolytic manganese sheet and to investigate ways of removing it most conveniently. APPARATUS The apparatus used is shown schematically in Fig. I. It consists of a chamber A in which the metal sample is placed, a vacuum or pressure gauge B, volume gauge C, vacuum pump D, hydrogen container E, auxiliary gas chamber F, and furnace G. The specimen chamber was made of two concentric quartz tubes. The outer one, a, connects with the closed gas system and is surrounded by the furnace G. A second tube, b, fits closely inside a and has a small end that projects into the space for the specimen and holds the thermocouple for measuring the temperature of the sample. The inner tube is joined to the outer tube outside the furnace, with rubber tape and sealing wax, to prevent gas leakage into or out of the closed system. This type of specimen container is loaded very easily and can be used several times if molten metal does not come in contact with the quartz. An ordinary mercury manometer B is used to measure the pressure in the system. The volume gauge C is essentially another mercury manometer, but the volume of the column is much larger than normal and the height of the mercury can be varied by raising or lowering the well H. In this apparatus the tube had a volume of I00 c.c. for a 60-cm. length. For larger changes in gas volumes; auxiliary containers F were used to increase the volume of the system by known amounts. Valves were arranged so that these auxiliary containers could be filled from the system and evacuated by the pump as often as necessary to accommodate the increases in the volume of gas in the system. The furnace G, used to heat the samples, was equipped with an automatic temperature controller, which maintained the desired temperatures within ± 5°C.

Jan 1, 1945

By Frederick Rhines

THE investigations of Wyman1 have demonstrated that copper deoxidized with several of the commonly used agents that confer immunity to ordinary hydrogen em-brittlement can still be embrittled if it is annealed alternately under oxidizing and reducing conditions. During the oxidizing cycle, oxygen diffuses into the copper and frequently deposits a subscale composed of the oxide of the residual deoxidizing agent. Upon subsequent reduction with hot hydro-gen, the copper becomes ruptured along the grain boundaries to a depth sharply limited by the previous penetration of oxy-gen as delineated by the inner boundary of the subscale. Obviously the sensitivity to this kind of hydrogen embrittlement is engendered by the introduction of oxygen during the oxi-dizing anneal, but beyond this the mecha-nism of the process, and hence the controlling factors, remain obscure. There are several possibilities: (I) oxygen dissolved in the copper matrix of the subscale may, upon cooling prior to the hydrogen anneal, precipitate as cuprous oxide which is subse-quently reduced by hydrogen as in the familiar case of hydrogen embrittlement; (2) oxygen in solid solution in copper may itself confer susceptibility to embrittlement by hydrogen; (3) the normally refractory oxides such as those of aluminum, silicon and titanium may themselves he reduced by hydrogen when in contact with copper; or (4) the precipitated oxides of the sub-scale may be complex compounds such, perhaps, as Si02-Cu20, which are partially reduced by hydrogen. These possibilities have been examined, and it has been con-cluded that the first three and possibly the fourth are operative collectively or indi-vidually under more or less predictable conditions.

Jan 1, 1940

By C. E. Sims, C. A. Zapffe

MANY hundreds of publications have appeared during the past 78 years that treat the subject of hydrogen in iron and steel,105 but conclusions regarding the functions of hydrogen in causing some important defects in steel are still unsatisfactory to many; and other hydrogen-caused phenomena yet remain to be identified with this gas. The most widely discussed of these defects is hydrogen embrittlement, but the conception, perhaps the popular one, that embrittlement is due to hydride formation does not conform to the known facts.104 The true identity of hydrogen embrittlement seems instead to lie in a mosaic nature of metal crystals, which is a concept not yet accepted by most metallurgists. A study of hydrogen embrittlement therefore provides new viewpoints in regard to the crystalline substructure of steel. A second widely discussed hydrogen-caused defect is the "flake" or "shatter crack." Although it is generally agreed that the presence of hydrogen is a prerequisite for their appearance, it is also realized that internal stress plays a decisive part. The relationship of hydrogen to internal stress has not been explained very clearly; nor is it always clear what the relationship is between a "flake" and a "snowflake," or between a "fish eye" and a "shatter crack." More importantly, the relationships among hydrogen embrittlement, hydrogen-caused fissures such as "flakes" and the ultramicroscopic structure of steel have scarcely been recognized. The present investigation attempts to provide an explanation for the embrittlement of steel by hydrogen by showing cause for accepting the "block" concept of metal crystals, and then to show how the numerous hydrogen-caused defects are interrelated in the light of this concept. EVIDENCE OF SUBSTRUCTURE IN METAL CRYSTALS It appears that the concept of a crystal as an aggregate of smaller multi-atom units must be accepted in some form if the behavior of metals is to be understood. The abundant literature on the evidence of an ultramicroscopic "mosaic" structure in metals and other crystalline substances suggests that the physicist has provided the metallurgist with an invaluable new insight. The exact picturization that any one physicist provides may be open to question, but the fact that there is some such fundamental substructure seems undeniable. The present work makes no pretense of comprehensively treating the imperfection structure theories. Nor will conclusions be drawn here regarding the exact nature of the substructure of crystals. However, the acceptance of some imperfection theory of fundamental attributes seems so necessary to an understanding of the behavior of hydrogen in steel that the following brief

Jan 1, 1941

By Yves Dardel

INTRODUCTION SINCE the first determination of Dumas1 in 1880, many authors have tried to measure the solubility of hydrogen in solid aluminum, or at least the amount of dissolved gas in it. However, the interpretation of the results which have been obtained is still difficult. Sieverts,2 then Baukloh and Oesterlen,3 during their gassing experiments could not determine any solubility of hydrogen in solid aluminum. On the other hand, Portevin, Chaudron and Moreau,4 leaving the determination of the hydrogen solubility beyond the scope of their experiments, measured only the amount of gas that they could extract by high voltage positive ion bombardment and found up to 151 cm3 of gas per 100 g of metal. Winterhager,5 by repeated vacuum extraction during severe cold rolling, extracted up to 161 cm3 per 100 g. In both series of experiments, the extracted gas contained chiefly hydrogen with a small amount of nitrogen, carbon monoxide, carbon dioxide and methan. Later, Schmidt and von Schweinitz6 as well as Chaudron and Moreau7 showed the importance of the adsorbed layer of hydrogen, the extracted quantities being proportional to the surface and not to the weight of the sample, when its cleaning was not perfect. In earlier experiments, Steinhauser8 extracted from more massive samples nothing but a little amount (< 0. 5 cm3 per 100 g) of hydrogen, carbon monoxide and methane. Thus, according to these experiments the quantity of dissolved gas is probably very small and the effect of the surface could falsify the results of the extraction. However, owing to the care taken by Chaudron and his coworkers, it was clear that all the hydrogen extracted could not come from the superficial layer, or that the links which bound hydrogen to the surface were so strong that the usual method of cleaning could not destroy them. After the main parts of the experiments reported here had already been carried out, Eborall and Ransley9 published the results which they obtained with an analysor having an accuracy of 0.03 cm3 per 100 g, while that of the usual apparatus was only about 0.2 cm3 per 100 g. During all their experiments the adsorbed layer would have been a difficulty, for the value of the adsorbed hydrogen was approximately equal to that of the dissolved amount. [ ] Since always keeping the same adsorbed layer is very difficult, an error in the correction for the adsorption can be made when using the apparatus of Eborall and Ransley, as well as the earlier apparatus,

Jan 1, 1948

By R. S. Busk, E. G. Bobalek

THE relation between gases and metals has been a subject of increasingly active investigation during the past years, principally devoted to the study of metal-hydrogen systems. It has been found that hydrogen is soluble in most molten metals to an appreciable extent and somewhat soluble in most solid metals.1,2 In every known case there is a sudden decrease in solubility at the melting point. Thus a freezing mass of metal containing hydrogen in excess of the solid solubility must in some way expel that excess during the freezing process. This leads to internal blowholes, and such effects as pinhole porosity. Gas trapped in metal that is to be fabricated by a working process such as extrusion or rolling may be the cause of blisters. For some cases, notably in copper and iron alloys, the presence of hydrogen can lead to extreme embrittlement of the metal. The aluminum-casting industry has long recognized the importance of hydrogen in its techniques. Excess gas in molten aluminum alloys often leads to the formation of "pinhole porosity" in the solid casting.3 To prevent this hydrogen pickup it is necessary to avoid overheating the melt and to protect it from such sources of hydrogen as water. In spite of all precautions, it is sometimes necessary to extract hydrogen from the melt just before pouring by bubbling with a gas such as chlorine or nitrogen. Recently it has been found that somewhat similar effects are possible with magnesium alloys, in that the presence of hydrogen can induce or aggravate microporosity.4-6 This paper is primarily concerned with a presentation of some facts concerning the solubility of hydrogen in magnesium and its alloys, with some discussion of the significance of these facts in a practical sense. In any study of gas-metal systems it is important to bear in mind a clear distinction between adsorption on surfaces and absorption within the lattice.1 Considerable attention has been directed toward determining whether hydrogen is truly soluble in any solid metal, or whether the gas extracted from a sample was present at surfaces (external and internal) only.7 Most present day evidence supports the idea of true solution in addition to adsorption. A second important factor when dealing with gas solubility is the dependence of such solubility on external pressure. For diatomic gases such as H2, solubility in both liquid and solid metals apparently is proportional to the square root of the pressure, indicating a breakdown to a monatomic gas before diffusion into the lattice .2 For true equilibrium values of solubility, therefore, the pressure at the metal surface must be constant and, preferably, known. Very little has been published concerning the hydrogen-magnesium system. Winterhager has presented the most

Jan 1, 1946

By Frank E. Caropreso, William P. Badger

A hydrogen peroxide precipitate process has been adopted by Atlas Minerals for the recovery of uranium oxides from sodium chloride strip solutions. Adoption of the process was based on laboratory and plant tests comparing hydrogen peroxide with other precipitants. Plant operation has demonstrated that the hydrogen peroxide process consistently yields uranium concentrates of high purity and barrens of low uranium content. Increased U3O8 concentration in the product, reduced levels of impurities which incur penalties, and higher product density have produced economic advantages.

Jan 1, 1974

By A. C. Fieldner, Lester L. Hirst, Henry H. Storch

Experimental work on liquefaction of coal was taken up by the Bureau of Mines in 1936 when it became evident that a prudent policy from the national point of view should include preparation for the time when gradual exhaustion of petroleum resources would require supplementing the growing demand for motor fuel with gasoline and diesel oil from coal. At that time (1936) certain foreign nations that had no home sources of petroleum, especially Germany, England, and Japan, were conducting active research and at least two of them were producing liquid fuel from coal on a commercial scale. Germany was reported to have an annual producing capacity of 800,000 metric tons of gasoline per year, and England had just put into operation the Billingham plant of Imperial Chemical Industries for the hydrogehation of bituminous coal and tar by the Bergius-I.G. process. The annual capacity of this plant was about 150,000 long tons of gasoline per annum (3500 bbl. per day). With these developments taking place in foreign countries, it seemed important to undertake a long-range program of fundamental research in this country to establish a sound groundwork for the evaluation of foreign work on synthetic liquid fuels and at the same time to obtain data on the oil yields and operating difficulties using various kinds of American coals and lignite to the hydrogenation process. The results of such research would be useful in determining the yields and quality of liquid products obtainable from various coals so that American industry would be in position to select the most suitable coals and make rapid progress in establishing this new industry when the commercial need should arise. It was hoped, also, that progress in a better understanding of the chemistry of coal hydrogenation would reduce the cost of the process materially. To carry out this program, a small continuous unit capable of hydrogenating 100 Ib. of coal in 24 hr. was installed at the Central Experiment Station of the Bureau of Mines at Pittsburgh, Pa. Small steel autoclaves or bombs of 0.3 gal. (1.2 liters) capacity also were used for batch-hydro-genation experiments in the study of the chemical fundamentals of the process. Much valuable assistance was obtained in planning the experimental program and designing the equipment from the Fuel Research Station of Great Britain and the Fuel Laboratories of the Mines Department of Canada, where such investigations had been in progress for several years. Equipment and General Procedure of Research The industrial liquefaction of coal by the Bergius-I.G. hydrogenation process as practiced at Billingham, England, from

Jan 1, 1944

By Lester L. Hirst, Henry H. Storch, A. C. Fieldner

Experimental work on liquefaction of coal was taken up by the Bureau of Mines in 1936 when it became evident that a prudent policy from the national point of view should include preparation for the time when gradual exhaustion of petroleum resources would require supplementing the growing demand for motor fuel with gasoline and diesel oil from coal. At that time (1936) certain foreign nations that had no home sources of petroleum, especially Germany, England, and Japan, were conducting active research and at least two of them were producing liquid fuel from coal on a commercial scale. Germany was reported to have an annual producing capacity of 800,000 metric tons of gasoline per year, and England had just put into operation the Billingham plant of Imperial Chemical Industries for the hydrogehation of bituminous coal and tar by the Bergius-I.G. process. The annual capacity of this plant was about 150,000 long tons of gasoline per annum (3500 bbl. per day). With these developments taking place in foreign countries, it seemed important to undertake a long-range program of fundamental research in this country to establish a sound groundwork for the evaluation of foreign work on synthetic liquid fuels and at the same time to obtain data on the oil yields and operating difficulties using various kinds of American coals and lignite to the hydrogenation process. The results of such research would be useful in determining the yields and quality of liquid products obtainable from various coals so that American industry would be in position to select the most suitable coals and make rapid progress in establishing this new industry when the commercial need should arise. It was hoped, also, that progress in a better understanding of the chemistry of coal hydrogenation would reduce the cost of the process materially. To carry out this program, a small continuous unit capable of hydrogenating 100 Ib. of coal in 24 hr. was installed at the Central Experiment Station of the Bureau of Mines at Pittsburgh, Pa. Small steel autoclaves or bombs of 0.3 gal. (1.2 liters) capacity also were used for batch-hydro-genation experiments in the study of the chemical fundamentals of the process. Much valuable assistance was obtained in planning the experimental program and designing the equipment from the Fuel Research Station of Great Britain and the Fuel Laboratories of the Mines Department of Canada, where such investigations had been in progress for several years. Equipment and General Procedure of Research The industrial liquefaction of coal by the Bergius-I.G. hydrogenation process as practiced at Billingham, England, from

Jan 1, 1944

By Irwin Remson

Some unique hydrogeologic issues are inherent in the problems of siting, designing and licensing a mined geologic high-level nuclear waste repository. The problems involve hydrogeologically unfamiliar rocks for which little proven technology has been developed, long containment periods, elevated temperatures, and externally-imposed management constraints. In evaluating the existing national program, it should be recognized that hydrogeology is only one aspect of the total nuclear waste disposal problem, that the use of multiple barriers requires that the hydrogeologic system be considered in its entirety as a total system, and that engineering modifications can improve the isolation capabilities of certain barriers. Important research questions involve the mechanics of transport through dense fractured and unfractured rocks, methods for measuring vertical hydraulic conductivity, and a variety of geochemical questions. Current expectations for "high quality data" from either in situ or laboratory testing are unrealistic, and a modified approach to repository hydrogeology is needed. The dilemma is that the hydrogeological characteristics that make a potential host rock more satisfactory for respository siting are the same characteristics that are difficult to characterize and make the particular site more difficult to license. Finally, evaluation of the containment potential of any candidate site will become meaningful only with detailed underground exploration, mapping and testing in the host rock formations at the repository levels.

Jan 1, 1984

By W. A. Van Voast, J. J. McDermott, R. B. Hedges

Many coal beds that will be mined in southeastern Montana are aquifers that provide essential local water supplies. Mine cuts along aquifer outcrops create almost imperceptible piezometric changes. Monitoring near such operations at Colstrip has detected almost no water-level declines in observation wells. Mine cuts between outcrops induce rapid storage depletion and associated piezometric depressions. One such cut near Decker induced 12.50 mj/day of flow from storage and created a piezometric depression of 3 m or more as far as 1500 m from the mine. No wells have yet become nonproductive but losses of some are inevitable as operations expand. Alternative supplies are available from aquifers stratigraphically below the disturbed materials. Effluents from active mines are chemically similar to other area waters because they are mixtures of ground waters entering the mine cuts. Occasional high concentrations of nitrate do occur, however, as residuals from explosives. Spoils generally consist of confined aquifers of wasted coal and coarse rubble at their bases, overlain by finer-grained sand,

Jan 1, 1980

By A. M. Johnson

Dewatering is a major operational cost at some mines. Under certain conditions, costs associated with water disposal may continue beyond the productive bye of the mine. For mines with mineralized waters, this is of special concern. Since 1974 experience has been gained from examination of a number of closed underground metal mines that exhibited drainage problems. It was observed, in certain cases, that had appropriate steps been taken prior to closure, the resulting drainage problems could have been largely avoided. Reclosure steps would have involved alteration to the &apos;plumbing system" of the mines; i.e., the drifts and crosscuts interconnecting the mine workings. This could have best been accomplished by the placement of bulkheads and/or selective drifting. In addition to reconfirming that hindsight is 20-20, a lesson learned from these case studies shows that a relatively simple hydrologic evaluation prior to mine closure may avoid a troublesome and costly drainage problem.

Jan 1, 1985

By Frederick T. Fischer

The New Jersey Zinc Company began a program of exploration in Middle Tennessee in 1964. The target horizon of the exploration project has been the Knox Dolomite which is a low-yield aquifer over nearly the entire Central Basin of Tennessee (1). With the exception of a few hundred acres in the Wells Creek and Flynn Creek disturbances (astroblemes?), the Knox Dolomite in Middle Tennessee is known only in subsurface. In January of 1969, New Jersey Zinc announced the discovery of a major zinc deposit near Elmwood, southeast of Carthage. This is on the northeastern flank of the Nashville Dome where the nearly flat-lying beds have an average eastward slope of about 50 feet per mile. The anticipated development of a mining situation has emphasized the significance of hydrologic relationships in the region as a whole and especially in the Elmwood area. These relationships affect several areas of concern which ma be generally grouped into two broad classes; i. e. , (1) Problems of a Public Nature - involving the prevention of the contamination of potable aquifers, the prevention of the contamination of surface waters, the prevention of the capture of presently utilized water, etc.; and (2) Problems of Mining Economics - involving pumping capacity and costs, the possible need for equipment of special composition, underground environmental conditions, etc. Exploration drilling in Middle Tennessee has contributed additional information about the Knox aquifer and

Jan 1, 1970

By T. Turner, C. L. Zimmerman, U. Kappus

The purpose of the project is to divert flood flows of North Potato Creek. The project is located in the southeast corner of Tennessee near Copperhill, approximately 160 km north of Atlanta, GA. The project consists of: a 28-m high dam, a 0.9-m diam outlet conduit, an emergency spillway, and a 4.0-m diam hard rock transbasin diversion tunnel. This flood-water management system was part of Cities Service Co. mine safety program for the Cherokee ore body, which is partially located within the creek channel. The following paper describes the entire project development from feasibility studies to design and construction management.

Jan 1, 1981

By David R. Hargis, John W. Harshbarger

The Upper Santa Cruz Basin lies in the drainage area of the Santa Cruz River in Arizona, and extends upstream from the community of Rillito to the international boundary [(Fig. 1)]. The principal water use area lies between, and includes, the cities of Tucson and Nogales. A subsurface geologic barrier near Rillito provides a reasonable dividing line between the ground waters of the upper and lower Santa Cruz basins. The upper basin contains the Tucson and Sahuarita-Continental critical ground water areas. The Tucson water use area encompasses the Tucson metropolitan area and extends from the northern boundary of the basin south to the boundary between the Tucson and Sahuarita-Continental critical ground water areas near San Xavier. The San Xavier use area is the San Xavier Indian Reservation. The north and south boundaries of the Continental use area coincide with the limits of the Sahuarita-Continental critical ground water area. The first study of ground water in this valley was initiated by Dr. G. E. P. Smith in 1905, and the results were published in 1910, followed by a series of bulletins of the Arizona Agricultural Experiment Station, University of Arizona, covering the general field of ground water development and utilization. Beginning in 1939, the ground water branch of the US Geologic Survey, in cooperation with the Arizona State Land Department and the Arizona Water Commission (AWC), published a series of bulletins concerning ground water occurrence and utilization in various areas of the state. In 1975 and 1977, the AWC published the Arizona State Water Plan (Arizona Water Commission, 1975) comprising a detailed inventory of water availability and use in Arizona and a study of alternative futures. The importance of ground water supplies in the Upper Santa Cruz Valley cannot be overemphasized. Metropolitan Tucson, surrounding agricultural areas, and the mineral industry are completely dependent upon ground water. Agriculture has been the largest user of ground water. The land distribution of the Upper Santa Cruz Basin is rural in character with large tracts of land included in national monuments and national forests. The Upper Santa Cruz is one of several state basins that does not depend upon one single industry as its major economic activity. Agriculture, mining, tourism, international commerce, and manufacturing all contribute to a viable economy. The city of Nogales, on the Mexican border, and the city of Tucson, to the North, are the centers of commerce in the basin.

Jan 1, 1982

By Charles S. Robinson

Abstract-The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains, about 80 km (50 miles) west of Denver. The ore body is being developed for mining by workings that extend more than 1100 m (3500 ft) below the topographic surface. During construction of the mine workings, ground water in fractures in crystalline rocks has been encountered. From 1969 to 1973, Charles S. Robinson B Associates Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic records of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentay rocks and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreases with time. The rate of decrease inflow (or pressure) is exponential. By measuring the change inflow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 8, 1978

By Charles S. Robinson

The Henderson ore body is east of the Continental Divide in the Front Range of the Colorado Rocky Mountains, about 80 km (50 miles) west of Denver. The ore body is being developed for mining by workings that extend more than 1100 m (3500 ft) below the topographic surface. During construction of the mine workings, ground water in fractures in cystalline rock has been encountered. From 1969 to 1973, Charles S. Robinson & Associates, Inc., in cooperation with the engineering and geologic staffs of the Climax Molybdenum Company, a division of Amax Inc., studied the ground water geology of the Henderson mine development area. Detailed geologic record( of the Henderson mine were available as a result of the exploration, evaluation and development of the mine. Records of the flow, chemical composition and temperature of the ground water at and near the surface, from the entire mine, from portions of the mine, and from exploration holes drilled in the mine, were kept as the mine was developed. Where possible, ground water pressures in drill holes and changes in pressure with time, were recorded. The geologic, hydrologic and chemical data were correlated. The following conclusions were drawn from the correlations: The ground water in the Henderson mine occurs in fractures in Precambrian igneous and metasedimentary rock and in a series of Tertiary intrusive rocks. Two zones of ground water were recognized; an active zone, in which the fracture systems are recharged and discharged annually into the surface water system, and a passive zone, in which the fractures were filled with water in the geologic past. Discharge from the passive zone is through mine workings that intersect the fracture systems. Discharge from a fracture or fracture system is initially high but decreases with time. The rate of decrease in flow (or pressure) is exponential. By measuring the change in flow with time, it is possible to calculate the amount of flow at some given period of time in the future. Based on changes in rate of flow and pressure, and the geology, and assuming rates of mining of the ore, it will be possible to predict the volumes of water that will have to be handled during the life of the mine and the area around the mine that will be drained by the mining operation.

Jan 1, 1979

By F. M. Doyle-Garner, A. J. Monhemius

Hydrolytic stripping is the process whereby metal ions in a loaded solvent extractant are hydrolyzed by water, typically at 130°C to 200°C (265°F to 392°F). Equilibrium hydrolytic stripping tests were done on Versatic 10 solutions containing various metals, singly and in mixtures. Single solutions of Fe, Ni, Cu, Mg, and Mn precipitated [a]Fe2O3 Ni(OH)2 Cu2O + CuO, Mg(OH)2 and [?]Mn203 respectively, during hydrolytic stripping. Several mixtures containing iron precipitated magnetic spinel ferrites, MFe204. No other combinations formed mixed oxides. It is proposed that the mechanisms for hydrolysis and precipitation of iron in loaded Versatic solutions are similar to those for iron hydrolysis in aqueous solutions. Magnetic interactions between mixed carboxylate complexes are thought to be responsible for the homogenous nucleation of magnetic mixed oxides in preference to single oxides.

Jan 1, 1986

By B. Meddings

The technology involved in the Sherritt process for the recovery of nickel and cobalt from sulphide concentrates and mattes is presented in a manner which emphasises the chemistry of the process. The hydrometallurgical process takes advantage of the differing stabilities of the various oxy-acids of sulphur from thionates through thiosulphates to sulphate. Some separations are based upon stability differences, some upon kinetic differences and some upon valence state differences and similarities The engineering and economic factors involved in hydrometallurgy are not discussed in either detail or depth.

Jan 1, 1981

By K. Kobayashi, K. Ueda, K. Yamaguchi

Lead concentrates from Kuroko (black ore) mines, which contain 4-7% Cu, 55% Pb, 3-777, Zn, and 0.5-0.9% As, are pretreated by a hydrometallurgical process before electric furnace smelting with other lead resources from Kuroko. The hydrometallurgical pretreatment involves sulfuric acid leaching in the first stage and ferric leaching in the second stage. This paper describes the short history of lead recovery from Kuroko and the performance of laboratory tests and pilot plant and commercial operations.

Jan 1, 1985

By M. E. Wadsworth, G. W. Warren

INTRODUCTION Hydrometallurgical processes for the extraction of metal values can be divided into two broad categories: (a) Processes involving the treatment of high grade material (e.g. finely divided mineral concentrates); and (b) processes which treat lower grade material (ores, waste dumps, etc.). This discussion will be directed primarily toward the first category, but in either case a fundamental knowledge of the intrinsic kinetics and thermodynamics is necessary to understand the behavior of the system. The bulk of research efforts in the last decade along these lines has been aimed at the recovery of copper (1-8). However much information has also been reported on uranium (9, 10) , zinc (11) , cobalt and nickel (12, 13). More comprehensive reviews on these areas are also available (14). As discussed by Sepulveda and Herbst (15, 16) one of the most difficult problems facing process designers is the acquisition and scale-up of reliable information concerning the intrinsic kinetics of leaching systems. The scale-up or modeling of these multiparticle systems is far more complex than that of homogeneous ones. This is due to the numerous rate determining steps which are possible with heterogeneous reactions and the broad distribution of properties of a multiparticle feed such as particle size and mineralogical composition (16). In addition, other factors must also be considered such as interactions between particles, the anisotropic nature of individual particles, the effect of solution chemistry, and electrochemical phenomena. All of these factors must be taken into account, often simultaneously. The thrust of this paper will be to more closely examine how the factors mentioned above can be treated. Some elementary examples of

Jan 1, 1980