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By David J. Collins

The emergence of activated charcoal adsorption as the most popular recovery method for precious metals, has led to numerous innovations aimed at increasing the efficiency of the process. This article describes a change in traditional charcoal transfer methods which will aid in reducing charcoal attrition losses. Studies have shown that significant charcoal attrition takes place during transfer, be it when using airlifts or centrifugal pumps. Tests conducted at Pinson Mines indicated a 4 to 8% loss to the minus 20 mesh fraction of charcoal after three (3) hours of pumping charcoal. Tests conducted while the author was at Jerritt Canyon indicated that charcoal transfer was a major contributor to charcoal losses; a decrease in the amount of coarse charcoal (plus 12 mesh) and an increase in the amount of finer charcoal (minus 16 plus 20 mesh) was noted as charcoal was moved to the head of the adsorption circuit.

Jan 1, 1998

By R. A. Kirkland

The oxygen consumption method utilises an oxygen sensor to monitor the gas-phase oxygen concentrations in sealed chambers filled with reactive waste rock with subsequent confirmation of the oxygen content by gas chromatography. Results of experiments utilising low sulphide (<0.5w1%) waste rock yielded reproducible oxygen consumption rates on the order of 10-10 mol O2.kg-1. s-1. Petrographic analysis of the waste rock material indicated that the dominant sulphide mineral is pyrite (FeS2). Assuming a stoichiometry of 1.75 moles of O2 per mole of SO4 sulphate release rates were inferred to be between 6 and 18 mg SO4 kg-1 wk-1 Typically these results are 2 to 3 times greater than measured sulphate release rates from humidity cells. Our findings suggest that this techniques offers a rapid. cost efficient method for determining sulphate release rates in waste rock piles, even at low sulphide concentrations.

Jan 1, 2000

By ev, Ze&apos Reches

The growth of networks of shear fractures is explored in a series of experiments with samples of wet clay. The samples are subjected to plane strain deformation in a rigid apparatus. The individual fractures observed on the upper surface of the clay samples grow longer by three mechanisms: in-plane propagation, off-plane propagation and coalescence. New, active fractures cut and displace older, less active ones. The lengths of individual fractures display lognormal distribution in most cases and power distribution in fewer. The calculated length parameters in the experiments, as well as in three field cases discussed here, suggest that the fundamental parameters in fracture analysis are the normalized cumulative length and the length of the shortest fracture measured.

Jan 1, 1986

By R. G. Robins

The dissolution of metallic copper powder in aqueous solutions of cupric sulfate with ethylene under low pressure was investigated. The reaction stoichiometry obtained was:

Jan 1, 1988

By Carolyn S. Watkins, Thomas E. Ward, Debby F. Bruhn, Vern Winston, Mary Lou Rowland, Deborah K. Bulmer

The genetic characteristics of members of the genus Acidiphilium are poorly understood. As part of our study of the genetics of these bacteria, a search was made for an endogenous bacteriophage. Such a bacteriophage has been discovered. Several properties of the phage have been investigated. The phage has a lambdoid morphology and is somewhat larger than lambda. A variety of factors which affect phage stability have been investigated. The bacteriophage infects several of the strains that have been tested. Study of this bacteriophage should greatly increase our understanding of genetic mechanisms in Acidiphilium.

Jan 1, 1989

By C. Timothy Shaw, Michael Karmis, Hans de Ruiter

The Society of Mining Professors/Societät der Bergbaukunde was established during a meeting hosted by the Montanuniversität, Leoben, Austria, in 1990. Since then, the Society has primarily functioned as a European entity of senior academics in the mining engineering discipline. The Society is considered the natural successor of the historic Societät der Bergbaukunde, formed in the early 18th century and recognized as the world’s first international scientific society. At the 14th Annual General Meeting of the Society, in Milos, Greece, 2003, a decision was made to examine the role of the Society in global minerals education, to reassess its vision and membership guidelines and to develop the future direction of the organization. A special Planning Subcommittee developed a plan of action to allow the Society to transform and position itself as the premier global voice of the academic minerals disciplines and to lead the effort of restructuring minerals education. The new vision calls for reconstituting the Society as a vibrant global society, representing the majority of minerals academics and making a significant contribution to the future of the minerals disciplines. This paper will present the history, vision, goals and action plans of the Society to help ensure that the necessary scientific, technical, academic and professional skills are available for the sustainable supply of minerals to mankind.

Jan 1, 2005

By J. Loredo

In some rural regions of Peru, artisanal gold mining is currently an essential activity as it provides an important source of income. In the Huanca region (Ayacucho Department) gold deposits are not attractive for mining companies due to their reduced size, but they have enough interest for artisanal mining because of the ease and low cost of mining operations. Artisanal gold mining represents an important damage for the environment, because operations related to amalgamation processes using Hg result in special environmental problems besides the typical ones commonly associated to all mining activities. A preliminary sampling has been made in soils, materials from tailing ponds and surface water of the Acarí River, at the site of the Huanca village, according to networks specially designed for the particular conditions of the area. Studies accomplished revealed high mercury concentrations in soils and tailings. Chemical analyses of soils directly collected in the area of the active or abandoned ?quimbaletes? show mercury concentrations ranging from 15.3 mg?kg-1 to 44.2 mg.kg-1. Mercury concentrations in soils decrease as a function of distance from the before mentioned sources. Water quality of the Acarí River that flows through the area does not present important changes as a consequence of the mining and processing operations.

Jan 1, 2006

By J. Steenkamp, A. L. Hannaford, A. N. Jones

O’Okiep Copper Co. Ltd.’s 45-kt/month (49,600-stpm) concentrator at the Spektakel mine in South Africa is comprised largely of reconditioned equipment from the old O’Okiep mill, which operated from 1940-1975. When combined with modern approaches to layout, crushing, classification, and flotation, a simple-to-operate plant was constructed at a cost of only $3.2 million.

Jan 11, 1982

By A. M. Edwards

In many ways a government could be regarded as a macro business enterprise. Its shareholders are its peoples, the productivity of the nation depends on them, and, indeed, the profits or losses of a nation&apos;s balance sheet can be linked to the surplus or deficit in its balance of payments. International loans need to be repaid, and in most developing nations the noose is tied so tightly that one wonders if such debts will ever be repaid. In their endeavour to meet such obligations, their currencies may be devalued [sometimes in frightening proportions], in the hope of boosting the export potential. However, this is a vicious circle, since exports will not be achievable unless sufficient technical expertise and infrastructure exist to address the opportunities which may have been created through devaluation. Many of the poorer countries have exportable resources of minerals, which are supplied on the international market. This may be the good news, but, unhappily, steps were seldom taken to enhance the value of the mineral products through further beneficiation and the production of high-value sophisticated products. That is where the vicious circle comes in: inadequate infrastructure is created, competent and well-trained manpower is not generated, and the result has inevitably been that the GDP slips backwards, and the nation becomes progressively impoverished. To exacerbate the problem, it is unfortunate that the more impoverished a nation becomes, the greater is its birthrate, and hence the greater the need to create wealth at the very time that the nation is becoming poorer and poorer. Within this scenario, one may well reflect that this is exactly what nations on the African Continent are experiencing, namely exploding populations, although most of the poorest nations in the world are found on this continent. Yet they often possess a superior mineral production potential. Africa still suffers from what may be called the colonial influence, in that the developed world has regarded this continent as a source of raw materials to feed its own factories. The colonial powers gave only secondary attention to developing the nation&apos;s peoples and its infrastructure, such as railways, roads, harbours, and other services. These problems all naturally fall within the ambit of government interest, and it is therefore obvious that the state should play a dominant role in addressing them. The reasons for governmental involvement in mineral-related research and development differ considerably, depending on the state of industrial development of that country. Thus, in the highly industrialised world, government&apos;s interest will lie mostly in the fields of strategic minerals, which may not be economically exploitable. An example would be the exploitation of American low-grade chromites during the Second World War, or minerals which need to be imported from unfriendly or unreliable sources, such that disruption would not be in the national interest. Colonial powers like the United Kingdom and France established R&D facilities to assist, inter alia, in the exploitation of mineral resources in their colonies. The approach of developing countries would differ from that of the industrialised nations, in that their primary quest would be to promote, support and encourage the development of infrastructure, and the establishment of major industries in order to create and provide employment opportunities, as well as to support small operators who cannot afford to undertake their own research and development. On the debit side, it is a sad fact that, however good their intentions may be, underdeveloped countries are invariably unable to provide the requisite financial support to sustain their own research-and-development laboratories. In a high-tech world, the cost of sophisticated equipment is steep and cannot be afforded. Again, the proverbial vicious circle comes into play. The competent researchers find themselves without rewarding employment and would therefore shun such institutions. Recent trends in the developed world have been to privatise research-and-development institutions, the argument being that they should draw closer to the industry they serve, and that the provision of taxpayers&apos; money for strategic purposes is no longer as important as it may have been once. Complete state withdrawal has had its negative effect in that long-range, high-calibre research has tended to be replaced by short-term problem-solving projects. Industries engaged in the minerals business differ somewhat from major ones, like motor, computer or pharmaceutical industries, which are large enough to support their own internal research and development, and whose work is highly confidential, so that any leakage could have disastrous consequences. Furthermore, private companies are answerable to their shareholders and costly long-range, &apos;blue-sky&apos; research would be difficult to justify. Since mineral research has become of lesser importance in the sophisticated First World, this trend has persisted. On the positive side, R&D institutions which are totally financed by government, suffer because they tend to forget the reason for their existence. They have often become a form of auxiliary to an academic institution where higher degrees are collected by scientific boffins who, in their quest for academic excellence, tend to disregard the benefits that industry may ultimately gain from this research endeavour. The trend in recent years - and South Africa is no exception - has been for the state to progressively reduce its subsidy, whilst at the same time encouraging research organisations [for their ongoing survival] to interact closely with industry, and to conduct work directly for them on a contract basis. Organisations such as CSIRO in Australia, CANMET in Canada, the USBM in the United States and Mintek in South Africa all generate income from the private sector. However, the critical fact is that the State should never withdraw

Jan 1, 1995

By L. P. Meade

The need to feed an established talc mill from a crude ore source located closer to the mill prompted the 1986 drilling of a previously mapped, talc-carbonate deposit. This talc-bearing rock had never been considered a potential source of crude talc ore because of the high carbonate content and other deleterious minerals observed in outcrops. Selective mining, in-pit grade control and creative processing have allowed this deposit to be developed into an ore body. By definition, an ore body has to be a source of positive cash flow. With industrial minerals, this is determined as much by market acceptance as by ore tenor.

Jan 1, 1994

By Ronald R. H. Cohen, Margaret W. Staub

Two pilot scale bioreactors designed to treat acid mine drainage primarily using sulfate reducing bacteria were constructed underground at the Eagle Mine Superfund site in Minturn Colorado. The project was designed to test th applicability of microbiological treatment on water with high metals concentration and to test the process in an underground environment. Objectives were, 1) to compare metal removal, pH increase, and sulfate reduction in a single stage reactor with a double stage reactor of equal volume at varying flow rates; 2) to determine where within the substrate treatment occurs· and 3) to examine volume versus surface ara as a design parameter for optimizing metal removal processes. Results from the reactors showed that the single stage reactor and double stage reactor performed equally well for the removal of Cd, Cu, Pb, Fe, Mn, and Zn. pH increased above 6.5 in both reactors. Greater than 97% of metals were removed within the first ten inches of substrate. Volume proved to be a more useful parameter for determining removal rates than area. Using volume as a design parameter rather than surface area enables PMDT systems to be constructed as packed columns rather than broad wetlands, Thus, space requirements are significantly reduced.

Jan 1, 1993

By F. N. Kissell, H. K. Sacks

This study examines the accuracy of area sampling for measuring the dust exposure of mining machine operators in coal mines. The specific objective of this research was to find locations where an area sampler might work better than earlier studies have indicated. The results show that fixed-location area sampling cannot accurately predict the dust exposure of a machine operator, even when the best fixed location is sought, the fixed location is quite close to the operator and the bias due to the dust concentration gradient is corrected. Industrial hygienists have known for many years that area sampling is unsuitable for measuring air contaminant exposures in the workplace. Near contaminant sources, the dilution air and the contaminants are not evenly mixed. Therefore, when workers are near contaminant sources, exposure measurements must be taken from the worker&apos;s breathing zone to be accurate.

Jan 1, 2003

By R. H. King, R. E. Cameron

Mine managers need better information to locate new opportunities and then to assess the effect of their decisions. We are developing the Intelligent Decision Support System (IDSS) and its two major modules, the Pattern Recognition System (PRS) and the Knowledge Representation Subsystem (KRS) to automatically provide the information from monitoring system sensors. This paper focuses on the KRS Algorithms that extract key information from lists of time-study type event sequences. Because a static system cannot operate effectively in a dynamic mining environment, we are prototyping an index- based technique that allows the system to adapt itself to this dynamic environment.

Jan 1, 1991

By Jerzy F. Sobala

Large - scale tests at the Polish Safety in Mines Institute /established in 1925 as "Barbara" Experimental mine/ performed in underground and surface experimental galleries, simulating conditions in roadways in mines, are the basic source of knowledge about development and propagation of explosions. Investigations up to 1973 were performed under the Institute&apos;s former research director Professor W.B. Cybulski s supervision, whose handbook concerning combating of coal dust explosions in collieries has been also published in the U.S. (2), and are continued until now. For investigating explosions the "Barbara" Mine disposes of 170 m /7.5 sq m/, 200 m /5 sq m/ and 400 m /7.5 sq m/ underground gallieries as well as of 10 m, 25 m, 44 m and 100 m surface galleries. For example, in the 200 m gallery more than 5200, and in the 400 m gallery - more than 2200 test explosions have been performed. Basing on determination of explosion hazard in roadways in collieries and on data of scientific research performed at the Safety in Mines Institute, the strategy of combating the explosion hazard in mines was elaborated; it includes mainly diminishing of coal duet. deposition in roadways, and -because of the possible inefficiency of this safety means in some roadways in mechanized collieries -- the introduction of three additional defence lines against coal dust explosions. It should be mentioned that at the "Barbara" Mine the problem of coal dust explosion initiation was elaborated as contract work for the U.S. Bureau of Mines. The main aim of this paper is to discuss some aspects of methods and measures for combating coal dust explosion hazard in highly mechanized mines in the Polish mining industry where in some roadways explosible coal dust is present, but it is not the aim to evaluate the effectiveness of methods and measures for diminishing the make-up of coal dust and coal dust deposition rates in roadways.

Jan 1, 1980

By K. Sasaki, T. Murakami, S. Akibayashi, Q. Wei

A numerical analysis and an experiment were done on groundwater flow past a bore hole with a cylindrical obstacle at its center. Flow around the obstacle in the bore hole was studied in detail. Two dimensional governing equations to simulate this flow were written for the hydraulic head and seepage velocity in a porous medium and for the vorticity, stream function, and velocity in the bore hole. These equations were non-dimensionalized and solved by using the alternating direction implicit and successive-over-relaxation finite difference methods. Flow visualization experiments and velocity measurements in the bore hole were done with a two dimensional model composed of a porous medium. The numerical analysis procedures were validated by a comparison of numerical and experimental results. Effects of the Reynolds number and obstacle size on flow in the bore hole are clearly shown in the velocity and streamline profiles. The quantitative relation between the seepage velocity in the porous medium and the velocity of flow around the obstacle in the bore hole also were estimated.

Jan 1, 1996

By C. Alexander

Stillwater Mining Company is developing a second underground palladium and platinum mine approximately 21km (13 miles) west of their existing Nye operation in south central Montana. A 5650 meter (18,550-foot) tunnel is required to gain access to the ore bearing horizon (J-M Reef). Access and primary mine development can be accelerated through the use of two 4.6 meter (15-foot) diameter tunnelboring machines (TBM). One TBM was purchased new while the other was purchased used. Machine specifications, site support facilities, portal/launch chamber construction, TBM assembly, startup and operation are discussed in this paper.

Jan 1, 1999

By Liang Ruilu, Guo Lihua

In light of the properties on process mineralogy of the old tailings in a certain copper mine in the People&apos;s Republic of China, a new process of combined reagent and stepwise flotation is applied in which the flotation of copper sulfides is followed by the flotation of copper oxides. Recoveries of copper and associated gold and silver have been greatly increased. The tailings obtained were subjected to the gravitational separation-magnetic separation process to recover iron minerals. Tailings from iron separation are taken as fillers and sent to the pit underground. Thus, the secondary resources are comprehensively utilized.

Jan 1, 1995

By C. M. Rastle

Resource Technology Associates (RTA) has developed a flocculation-flotation process that increases phosphate recoveries from current operating plants. A major advantage of the process is the ability to float the phosphate from the matrix without a preliminary separation to remove the slimes. A majority of the material that is now discarded in the slime fraction will be recovered in the new process. The process can also be used to recover phosphate material from current slime ponds either as a separate feed or mixed with matrix material. Flotation tails from the process demonstrate improved dewatering characteristics then those seen from conventional float tails.

Jan 1, 1988

By J. H. Hill

The globalization of mineral markets and intense competition in downstream mineral-consuming industries such as transportation, agriculture, and construction are requiring raw materials suppliers to innovate, improve quality, invest in new technology, and control costs. Mineral specifications are becoming more refined, and pressure to improve products is felt from increasing numbers of competing producers, substitute materials, customers, and regulators. As a result, engineered mineral products are becoming more like manufactured ones in terms of cost structure, differentiation, and the importance of market driven, customer specific product development. Engineered mineral products are defined as those where the costs of refining and upgrading outweigh those of conventional mining activities (blasting, crushing, classification, haulage etc.), and where close control of physical and chemical parameters is required for customers&apos; processing and manufacturing applications. This includes industrial minerals such as calcium carbonate, kaolin, mica, specialty oxides, talc, and some metal powders. It excludes most metals and bulk commodity materials such as gypsum, lime, sulfur, and soda ash. Engineered mineral products are utilized in common household goods, and are at the forefront of industrial materials engineering in plastics, ceramics, composites, glazes, coatings, and construction materials. As a group, they introduce interesting questions to the minerals firm. Advanced materials or basic? Diversify or specialize? What are the implications of advanced materials and for mineral markets, and most importantly, where can the producer look for long-term value, volume, and profits?

Jan 1, 1993

By Victor F. Hollister

The great increase in post-World War I1 use of molybdenum was made possible by discoveries of that metal in porphyry molybdenum and porphyry copper deposits. This section documents significant porphyry molybdenum discoveries of the post-war period. The most important discovery was Henderson in Colorado. It is not only one of the world&apos;s largest and richest, but it was found by a team of geologists who defined the hood model and tested it successfully at Henderson. Under the leadership of Stewart Wallace, these scientists established a set of criteria for exploration for Henderson-type de- posits that was copied by the industry. The discovery bf vertical cylinder type porphyry molybdenum deposits was less renowned. Boss Mountain in British Columbia and then Mt. Pleasant in New Brunswick were given relatively scant notice, compared with the Henderson discovery. However, these deposits have geometrics distinct from that found in the typical hood, which directly affects their exploration characteristics. Mt. Pleasant, included in this section, is a well defined, near vertical breccia pipe. Both the Henderson and Mt. Pleasant discoveries were made by relatively small groups operating independently of the bureaucracy that characterizes large corporations. The management role in each case was one of encouragement. In addition, Wallace had the beneficial experience of working for Climax, whose objective was the discovery of porphyry molybdenum deposits. Henderson was the natural outgrowth of the exploration effort by those who studied and understood the Climax deposit.

Jan 1, 1991