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By W. E. L. Minter

Discussion by R.W. Hutchinson Minter's excellent recent paper (1990) on the great paleoplacer gold deposits of the Witwatersrand and its subsequent discussion (Cheney, 1991) and reply (Minter, 1991) provide an informative, interesting and up-to-date review of the geology of these unique ores and some long enigmatic questions regarding their origin. Clearly summarized by Minter (1990) are the compelling sedimentologic and stratigraphic relationships indicating that the Central Rand Group conglomerates are ancient placers and documenting the fluvio-deltaic conditions of their transport and deposition. As Minter (1991) indicates, Cheney's discussion broadens Minter's 1990 coverage of the subject by considering higher and lower stratigraphic units and by adding detailed comments concerning recently published information about metamorphic and age relationships. Cheney's discussion and Minter's reply also readdress the old controversy of epigenetic hydrothermal vs. syndepositional placer origin for these deposits. This controversy has been resurrected by: • recent recognition of hydrothermally-altered granites (HAGS) in the older Archean basement rocks that lie unconformably beneath the Dominion Group rocks north and west of the Witwatersrand depository; • recognition of greenschist metamorphic assemblages in the Witwatersrand strata; and • the presence of interpreted epigenetic mineral assemblages and textures in some of the deposits. These relationships are briefly discussed by Cheney who suggests they may result from later, superimposed metamorphism and deformation and do not prove that the gold was introduced by epigenetic/metamorphogenic processes. In his paper, Minter (1990) cited the 1986 abstract of a subsequently published paper by Hutchinson and Viljoen (1988) who also considered many of these aspects and attempted to integrate them all in abroad genetic hypothesis. In addition, they emphasized the additional important problem of determining the source for the Witwatersrand gold. Although this issue was partially addressed by Reimer (1984), Mossman and Dyer (1985) and Reimer and Mossman (1990), the question has been generally under emphasized in earlier work and was, therefore, not stressed by Minter and Cheney. Reimer (1985) also emphasized the importance of weathering of the basin's Archean hinterland and its affects on Witwatersrand sedimentation. Since the epigenetic hydrothermal hypothesis was essentially discarded in favor of placerist origin, the gold source for these great deposits has generally been attributed to the weathering of lodes in greenstones or granites of the uplifted, older Archean hinterland to the north and west. However, Hutchinson & Viljoen (1988) present evidence that this explanation is inadequate, as well as data in support of an alternative explanation. They suggest that the gold and accompanying abundant, clearly detrital and auriferous pyrite in the conglomerate reefs were derived by erosional degradation of auriferous-pyritic exhalite previously deposited, by shallow marine discharge of hydrothermal fluids, along the fault-bound northwestern margins of the Witwatersrand depository. The auriferous-pyritic exhalites were generated by fluid-rock reactions in the subsurface, particularly in the highly-altered lavas of the Dominion Group but also in adjacent basement granitic rocks. The process envisaged is comparable to that observed in sea floor hydrothermal systems today, although, in this case, it occurred at the margin of a rapidly subsiding, shallow marine or continental basin. Important evidence for this explanation is the anomalous gold content of the ferruginous, shaley strata occurring throughout the Witwatersrand Supergroup and including the distinctive contorted bed that is an iron formation. These layers have been interpreted (Hutchinson and Viljoen, 1988 and 1990) to represent the more distal, finer-grained, mixed chemical/clastic sedimentary strata. Thus, they are the basinal equivalents of the proximal, auriferous-pyritic exhalites that were deposited along the basin's margin and subsequently reworked by sedimentary processes. This gold source explanation resolves many of the enigmatic questions regarding Witwatersrand geology and the reawakened controversy between proponents of hydrothermal and placerist genetic hypotheses. The theory invokes a hydrothermal origin for the gold in the basin-margin pyritic exhalites, thus explaining the visible hydrothermal characteristics (Figs. 1 and 2). It also provides compelling evidence for placer origin by encompassing all of the fluvio-deltaic processes of clastic sedimentary transport and deposition that are clearly summarized by Minter. These characteristics result from the degradational reworking of the pyritic exhalites along the depository's margins. Fluvial reworking, transport and deltaic redeposition of this detritus, along with additional detritus carried into the depository from the hinterland, then formed the conglomerate reefs. Other enigmatic aspects of Witwatersrand geology include: • the rarity of magnetite and ilmenite (the two most common heavy minerals in placer deposits) and the contrary abundance of leucoxene in the conglomerate reefs; • the presence of differing varieties of pyrite (authigenic, allogenic, compact and porous) all of which are auriferous; and • the presence of well-rounded pebbles, even cobbles, of pyrite that, in view of the brittleness of the mineral, could not have been transported great distances from a hinterland.

Jan 1, 1993

By David A. Grisafe

Divided opinions concerning dredging-permit locations and boating uses on the Kansas River in northeastern Kansas led to a study of the recreation potential on the river by a legislatively mandated interagency group (five agencies) that included the Kansas Geological Survey (KGS). In addition, the KGS conducted its own study of the river corridor, encompassing the development, geology, and economic resources of the corridor (Brady and others, 1998). The corridor area is 12 mi wide and 140 mi long (171 river miles). Included in the study was the potential impact of restric¬tions to river dredging. The Kansas River and its floodplain in northeastern Kansas are underlain by Lower Permian and Upper Pennsylvanian limestones and shales. The river and its floodplain are the major sources of sand and gravel for northeastern Kansas, and the limestones along the river bluffs supply crushed stone and building stone. The population of the 10-county area bordering the river has grown by 20% since 1980, and now comprises nearly 40% of the state's population (U.S. Bureau of the Census, 1996). Projections (Floerchinger, 1992) indicate close to 50% of the Kansas population will reside in these counties by 2025, with a continued increase in the demand for aggregates. Factors such as floodplain width, price and availability of land, and overburden ratios tend to favor river dredging on the lower part of the river, and floodplain or pit dredging on the upper portion. The use of alternate sources of sand and gravel such as the Missouri and Arkansas Rivers would increase sand prices due to transportation costs to much of the 10-county area. In 1996, river and pit dredges along the Kansas River supplied more than 3 million tons of sand and gravel valued at about $8 million to northeastern Kansas. As a result of its study, the KGS had concerns with the idea of large recreation zones on the river that excluded river dredging in areas of presently large population and projected population growth. This controversial issue is likely to recur elsewhere.

Jan 1, 1999

By G. E. S. Valadao

Filtration is an important solid liquid separation technology employed widely in the mineral processing industries. The effectiveness of the filtration operation can be influenced by numerous variables, related to the particulate phase, the slurry rheology and the equipment. The classical approach for analysis is based on Darcy's law. Knowledge of the cake pore microstructure and its correlation to macroscopic cake properties is required to model the filtration operation from a fundamental point of view. Since cake formation seems to occur randomly, a 3D Monte Carlo method was used to simulate cake formation. The configuration for simulation was a space with width of 500 µm, length of 500 µm and height of 4000 µm. Size distributions of five different industrial products whose particle size distributions follow the Rosin Rammler distribution function were used. The particle shape was assumed to be spherical. The simulated cake structures were described in terms of volume porosity (volume of pore space per unit volume of cake) and surface porosity (area of pore space per unit area of a cross section). The results indicate: I) it is possible to simulate 3D packing, which mimics cake structure, using the Monte Carlo method, 2) segregation phenomena occurs during simulated cake formation, 3) the values of calculated porosity for simulated samples B, C, D, and E were lower than those determined for corresponding industrial products Br, Cr, Dr, and Er, and 4) some structures of simulated samples seem to correlate with laboratory leaf test data obtained for different products from plant operations.

Jan 1, 1999

By S. Chunhui, W. Anbin, R. B. Cook

The Xicheng is one of China's largest lead-zinc (Pb-Zn) districts with known minable reserves in excess of 10 Mt (11 million st). The centrally located Changba-Lijiagou and nearby deposits are representative of the district. They consist of stratiform and stratabound zones of pyrite-sphalerite-galena mineralization within deformed, moderately metamorphosed Middle Devonian clastic and carbonate units. When considered with other similar districts that extend for several hundred kilometers to the east, a major episode of Devonian sedimentary exhalative mineralization is indicated.

Jan 1, 1992

By Kim B. Shedd, Erin A. McCullough, Donald I. Bleiwas

"The earliest known use of cobalt was to make blue glass in Mesopotamia before 2000 B.C.E. Since then, innovations across many diverse industrial sectors transformed cobalt into an essential commodity for contemporary society. The physical and chemical properties of the element cobalt and its alloys and compounds make them indispensable for a variety of applications, including aircraft engines, hybrid electric vehicles, machine tools, missile guidance systems, petroleum refining and smartphones. As a major industrialized nation, the United States is a leading consumer of cobalt and cobalt-containing products. However, with few exceptions, U.S. cobaltcontaining ore deposits are of low cobalt grade. Historically, U.S. cobalt mine and refinery output have not met domestic cobalt demand. As a result, U.S. cobalt chemical and alloy producers need to procure most of their cobalt from the international market, which can become susceptible to supply risk.The 1978 Cobalt Crisis illustrates supply risk. At that time, the Democratic Republic of the Congo (DRC) (then known as Zaire) was the world’s leading producer of mined and refined cobalt. An insurgent invasion of the country’s copper-cobalt mining region during a period of high cobalt demand and low producer inventories caused a temporary supply shortage in the international market. The monthly average cobalt spot price increased from $18/ kg ($8/lb) before the crisis to $99/kg ($45/lb) seven months later. The high price and concern about potential disruptions in supply prompted manufacturers to reduce or substitute for cobalt where possible, and encouraged increased recovery of cobalt from scrap. The DRC has regained its position as the leading producer of mined cobalt globally and continues to be characterized by high governance risks (U.S. Central Intelligence Agency, 2015; World Bank, undated). This article will present current and historical world cobalt production trends, which can help inform discussion about the variety of international supply chain risks consequential to its trade."

Jan 12, 2017

The fundamental objective of mine plans are usually to maximize the mine profit by extracting ore at the lowest possible cost over the mine life while some technical constraints are satisfied. Since the costs associated with the operation of trucks and shovels as resources are significant, determining the optimum number and allocation of these resources is an essential issue. This paper presents a Mixed Integer Linear Programming (MILP) model to determine the optimum number of shovels and trucks required to meet the short-term plan?s goals. Also, the model takes into account the allocation of trucks and shovels to mining faces. This model minimizes operational costs, while attempting to meet the production demand and to satisfy technological constraints. This paper also analyzes the operations of trucks and shovels in an open pit mine using ARENA simulation software.

Jan 1, 2012

By Ioannis Nicolaou

This paper demonstrates the method of approach for the optimization of such filters. This does not only incorporate the proven and simple recently developed equations for the calculation of the solids throughput, the residual moisture and gas throughput, but also introduces equations for the calculation of the specific product costs for both vacuum and hyperbaric filtration under consideration of the influences exerted by the filter compressor and a possible thermal drying. An easy-to-use method is offered which incorporates a special graphic representation concerning the plotting of the target parameters in dependence of the pressure difference with which the optimal process pressure difference can be established, independent of the specific cake permeability or product fineness. Finally, the optimization method is exemplarily demonstrated for a concrete application.

Jan 1, 1995

By Rodney K. Morrison

MARTA, The Metropolitan Atlanta Rapid Transit Authority, is building a 53 mile heavy rail transit system to serve the City of Atlanta. Phase A of the Rail System, consisting of approximately 14 miles of at-grade, aerial and subway construction is underway. Metropolitan Atlanta lies in the Piedmont Geologic province of Georgia and is underlain by rocks of essentially granitic and gneissic nature. The soils encountered are primarily silty sands which are in-place weathering products of the parent rock and exhibit their relic structure. In general, these materials have presented no unique construction problems other than those created-by proximity of manmade structures, local availability of ground water, and top of rock elevation. The subway sections of primary interest in this paper consist of hardrock and soft ground tunnels and extensive cut-and-cover sections. The cut-and-cover construction includes excavations as deep as 80 feet. Temporary support systems in these deep excavations consist of soldier pile-timber-lagging or soldier pile-tremie concrete (SPTC) walls with internal bracing or tiebacks. In shallow cut-and-cover sections, where right-of-way economics permitted, slopes were laid back partially or fully to reduce or eliminate the need for bracing systems. Dewatering systems were required in most open cut excavations. Due to the close proximity of utilities and existing structures to the MARTA

Jan 1, 1979

By R. V. Ramani, R. Bhaskar

The results of an experimental and theoretical research study into the spatial and temporal behavior of dust in mine airways is summarized. Experiments were performed in mine airways under both controlled and normal operating conditions. The controlled experiments included the documentation of the concentration and deposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using real-time aero- sol monitors (RAM-I) to determine the dispersion coefficient in a mine airway. On the theoretical font, a convection diffusion model of the dust flow phenomenon in mine airways was developed considering dominant mechanisms affecting dust transport and deposition in mine airways. Mechanisms modeled include turbulent and gravitational deposition, coagulation, and dispersion. In this paper, comparative analyses of results (8 the controlled experiments with the predictions of the mathematical model are presented. In addition to the overall validity, the adequacy of the individual components of the model, such as deposition in the total and respirable range, and dispersion are examined in light of the experimental observations. The experimental data from controlled experiments compared more favorably with model predicted results for similar conditions as opposed to the comparative analysis results for in-mine experiments. Specifically, the model predictions for an 800-m stretch of a mine airway reveal some significant differences from the behavior noticed in the mine. The deposition was lower than that predicted by the model. Consequently, concentrations were higher than those predicted by the model. The implications of these and other findings for further investigations are discussed in the paper.

Jan 1, 1987

By M. K. Larson, R. G. Wade

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are studying the time- dependent response of rock stressed along weakness planes. The objective is to improve mine safety by reducing the number of roof falls that cause injuries and fatalities to miners. Researchers conducted direct- shear tests on mudstone overcored from a coal mine roof. Results showed frictional strength weakens with displacement along the shearing planes. Results of direct-shear creep tests also showed time-dependent deformation. Test measurements were compared to classical analytical models. Results suggest that the risk of roof collapse may be decreased through layout and support design to reduce creep rates and thus slow progression toward failure.

Jan 1, 2002

By Guillermo P. Salas

The Consejo de Recursos Naturales No Renovables of the Mexican government entered into an agreement with the United Nations in 1964 for the mineral exploration of a large area in Estado de Sonora, Mexico. The agreement called for a systematic exploration for copper in northern Sonora based on photogeologic mapping, aerial reconnaissance, and geochemical stream sediment sampling. The UN-CRNNR investigations resulted in the detection of anomalous copper values in sediment from the Arroyo Cruz de Cafiada. The anomaly was followed upstream to its source, which ultimately proved to be the La Caridad ore body (see Fig. 1). Soil copper and molybdenum values were found over a large area, and further detailed geologic and geophysical investigations were instituted of the anomalous area. David Coolbaugh was largely responsible for the follow-up work. An induced polarization (IP) survey found a roughly circular region of "highs" that coincided with a high soil copper anomaly. The circular anomalies ringed the topographic feature that ultimately was found to contain the Caridad ore body. Soil geochemical copper response over the ore body was subdued, because the soils were derived from a leached capping, whereas leaching in fringe areas that contained less veining was less intense. The ore body was also ringed by the typical high pyrite zone, and this was the anomaly detected by the IP survey. The UN began drilling in the fall of 1966. Eleven holes tested the IP-Cu geochemical high, but none were of commercial interest. The project was returned to the Consejo and was reviewed in the field by G.P. Salas and V.F. Hollister. It was found that the leached capping had not been tested by the past activities, and the Consejo elected to explore that area in 1967. The capping was evaluated by Salas and Hollister and drilling by the Consejo began in 1967. Commercial grade ore intercepts were found in the first hole. The Consejo drilled nine holes, of which eight were commercial. At least 90.7 Mt (100 million tons) of 0.8% copper were indicated by the Consejo in eight holes. The lesson learned in this discovery is that evaluation of leached capping is an important guide to exploration. The general-

Jan 1, 1991

By D. III Earley, R. L. Blake

The Bureau of Mines is investigating the potential for in situ mining (ISM) of gold and silver mineralization. This preliminary study examined samples from several types of deposits. It used light optical microscopy and the electron microprobe to characterize the ore and gangue minerals and textural features of these samples. This included the spacial relations between the target minerals and likely natural fluid channel ways. Low-grade disseminated deposit types from the western US were found to contain fracture- hosted or matrix-hosted gold and silver minerals, some of which are encapsulated by quartz or pyrite. Successful ISM application to gold and silver deposits needs this data in order to understand potential problems of the lixiviant reaching the ore minerals.

Jan 1, 1991

By C. J. Johnson, C. J. Bise

Abstract - As the US coal industry moves into the next century, it is becoming more apparent that the effective application of new technology is the only way it can remain competitive in the energy marketplace. Examples of this emphasis are with us today in such diverse areas as face- ventilation and excavation-equipment applications. The focus of this new technology is directed toward improvements in health and safety, cost control, and productivity. Room-and-pillar mining accounts for approximately 68% of the nation's underground coal production; this percentage is not expected to decrease markedly in the near future. As such, this paper analyzes the impacts of the changing techno- logical climate on future room-and-pillar operations by comparing a base-case section (current) to three scenarios incorporating new or emerging technology. A microcomputer-based comparative analysis will reflect the changes in section production and costs.

Jan 1, 1990

By W. Jacobi, F. Steinhausler, A. C. James

INTRODUCTION In 1979 the Committee on Radiological Protection and Public Health of the Nuclear Energy Agency (OECD) defined a programme of work needed to improve radon dosimetry and monitoring. A Group of Experts in this field was established by the NEA and at the first meeting of the Group the authors were designated an initial task with the following terms of reference:- To review dosimetry of radon, thoron and their daughters, and in particular:- - to examine analytical models for the assessment of dose to individuals who are exposed to aerosol mixtures of these nuclides; - to examine the state of knowledge of the characteristics of aerosol mixtures of these nuclides and other factors that influence the dose to the lung, and identify those parameters which should be measured for dosimetric purposes in radiological surveillance programmes; - to identify areas where further study or research are needed. In this presentation we attempt to examine, with these objectives, the relationship between exposure to radon and thoron daughter aerosols expressed in terms of the working level month l (WLM), or its SI equivalent, and dose accumulated by sensitive tissues of the lower respiratory tract. Over the past two decades many attempts have been made to calculate the lung dose equivalent to l WLM exposure in mine atmospheres, usually in terms of the maximum dose to basal cells in a small part of the bronchial tree. The calculations have employed variously detailed models of airway anatomy, aerosol deposition, ciliary clearance and dosimetry of tissue at the bronchial surface, and are well reviewed elsewhere (Walsh, 1970; UNSCEAR, 1977; Jacobi, 1977; Fry, 1977). They agree in the conclusion that basal cells in segmental bronchi (between about the third and fifth bronchial generations) receive the highest dose, although estimates of this dose differ by more than an order of magnitude, ranging from about 0.2 to 12 rads per WLM (2 mGy to 120 mGy). The most critical parameters of these models are the assumed depths of basal cells below the bronchial surface and the fraction of the WL carried by free ions. When more realistic values of these parameters are substituted (Jacobi, 1977), the dispersion in calculated maximum doses to basal cells is reduced to give a much smaller range from about 0.3 to 1 rad/WLM (3 to 10 mGy/WLM). The parameters and methods employed in these various models, however, remain too diverse to infer the sensitivity of the dose conversion to practical variations in aerosol characteristics and the additional factors determining lung deposition and clearance. We have therefore taken the approach of developing newer models (Jacobi and Eisfeld, 1980; James et al, 1980) that can encompass the range of available experimental data on the physical and biological behaviour of radon and thoron daughters and also accommodate the different interpretations that can be put upon them. We have paid particular attention to the averaging of dose over tissues of equal sensitivity in the lung

Jan 1, 1981

By J. B. Hiskey, X. H. Jiang

The extraction of gold from chloride solutions by ion exchange is examined. It is shown that at initial gold concentrations between 1 - 5 ppm, 20 g/l C1- and pH 5, the kinetics of loading on weak base resins are slightly slower than those observed with activated charcoal. Equilibrium loading of auric chloride varies considerably as a function of pH from one resin to another. For all of the resins studied, nearly complete gold extraction was achieved between pH 2 and pH 6.5. Sodium hypochlorite was found to exhibit a slight effect on the equilibrium loading of gold chloride.

Jan 1, 1990

By B. S. Hulvey

Thin support liners are becoming more accepted and being developed with improved properties because the mining industry as a whole has been offering underground safe test trial sites. This is because of the huge potential for such products. Recent developments tend to indicate that the technology is “coming of age” and these are discussed in this paper.

Jan 1, 2003

By Hans G. Machel

In low-temperature diagenetic environments (0 c T c 60 - 80°C), elemental sulfur forms by six common processes: via (1) inorganic oxidation of H2S by molecular oxygen, (2) inorganic oxidation of H2S by ferric iron compounds, (3) polysulfide disproportion- ation; and via the microbial metabolic actions of (4) colorless sulfur bacteria, (5) colored sulfur bacteria, and (6) some types of thiobacilli. Economically viable deposits of native sulfur usually are formed by only one process: inorganic oxidation of H2S by molecular oxygen. The amount of elemental sulfur is also limited by three common processes that destroy it in low- temperature diagenetic environments: bacterial reduction, bacterial oxidation, and inorganic oxidation. In high-temperature diagenetic environments (80 - 10o°C c T c 150 - 200°C), particularly in sour gas reservoirs, there are seven common processes forming elemental sulfur: (1) SOdH2S reaction, (2) H2S- hydrocarbon reaction, (3) polysulfide disproportionation, (4) catalytic H2S decomposition, (5) C02-H2S reaction, (6) chlorinification, and (7) exsolution of physically dissolved elemental sulfur. Natural processes that destroy or remove elemental sulfur in such settings are hydrocarbon sulfurization, polysulfide formation, and advection. In most sour gas reservoirs, relatively small quantities of elemental sulfur occur as a free phase (solid or liquid). However, elemental sulfur often precipitates in copious amounts from the reservoir fluids via exsolution and polysulfide disproportionation during production of sour gas reservoirs. By extension, elemental sulfur may precipitate from reservoir fluids in relatively large quantities upon uplift and erosion of deep sour gas reservoirs, or from advection of sulfurous fluids into shallower settings via faults or other high-permeability pathways.

Jan 1, 1992

By F. F. Peng, S. S. Peng, V. Z. Sun

A detailed study of ponding phenomenon relative to surface subsidence due to longwall mining was conducted for various surface stream conditions. Based on field monitoring, the stream-ponding process and three forms of stream water are described. Also discussed are the criteria of stream ponding and the influences on the ponding process by two key factors: the angle of stream flow and the change in the stream-bed gradient. A numerical (mathematical) model, which combines trend surface technique that describe the topographical features in the vicinity of a stream and the modified influence function, which represents the profile of the surface subsidence trough (or basin), is constructed to predict the formation characteristics of stream ponding in terms of location, boundary and accumulated water volume of migratory and stationary ponds produced by the stream-ponding process. Three cases are analyzed using the model to predict the interaction of the underground operations and the environmental impact due to stream ponding. The feasibility of various mitigative measures are assessed.

Jan 1, 1997

By Slawomir Bock

One of the fundamental issues having a great influence on the safety of operations performed in underground mines is the support of workings which should assure their stability in a given geological setting and mining-technical conditions during the life of their use. The process of designing and planning support for roadways may use analytical and empirical, as well as numerical methods. In view of the rapid increase in the data processing capacity of computers and the development of more and more enhanced software for numerical modeling, it seems to be advantageous to use numerical methods in searching for design solutions ? especially in the case of non-typical mining and geological conditions and in cases that need to take into consideration a great number of factors. The assessment of rock mass quality is of basic significance in designing mine supports. Fractures, dividing the rock mass into blocks, have an essential influence on the stability of the rock mass and underground construction. This paper presents examples of the fundamental underground investigations on the rock mass conducted by the Department of Extraction Technologies and Mining Supports of the Central Mining Institute in Poland, such as: penetrometric tests, introscopic examination, laboratory testing of rock samples and ground penetrating radar. Moreover, this contribution also presents examples of applications of three-dimensional numerical modeling for the purposes of stress-strain analysis of the rock mass around mine workings and computer-aided support design by means of FLAC3D (developed by Itasca) and Cosmos/M (developed by Structural Research and Analysis Corporation).

Jan 1, 2009

By K. Osseo-Asare

Metal recovery from solution, i.e., the formation of a solid product from a purified aqueous electrolyte solution, is increasingly becoming more than a simple matter of bulk precipitation. In many cases, operating conditions must be carefully manipulated to control the rate and yield of the precipitation/crystallization process, as well as the purity and physical characteristics of the solid product. A review is presented of the underlying physico-chemical processes, with emphasis on solution and interfacial chemistry. Opportunities for the integration of hydrometallurgical metal recovery and materials processing operations are discussed.

Jan 1, 1989