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By L. Figueroa

Electrochemical methods have potential to treat waters impacted by mining, while simultaneously producing a recoverable metal product to off-set treatment costs. Mining-impacted waters may present challenges with electrochemical treatment due to low concentrations and complex solutions of numerous dissolved metals. This paper presents an evaluation of the potential strengths and limitations of abiotic electrowinning of mining-impacted waters. In particular the impacts of chemical composition on metals removal are evaluated. Results of bench-scale experiments demonstrate the potential to remove metals on the cathode (copper, cadmium, lead), as well as the anode (manganese). Pre-treatment for iron and aluminum may be needed and post-treatment pH adjustment would be necessary. INTRODUCTION Due to continually increasing demand for metals, new technologies and innovative applications of existing technologies are needed to recover metals from mining-impacted waters. Electrochemical methods have long been used for metallurgical processes with solutions containing high concentrations of the target metal. However, electrochemistry also has potential to treat waters with lower metal concentrations, while simultaneously producing a recoverable metal product to offset treatment costs. Electrochemical water treatment may have several benefits over traditional alkaline treatment for acid rock drainage (ARD). Sludge produced from alkaline treatment has high water content that is difficult to dewater, even for treatment plants producing a relatively high-density sludge. For example, the Argo Tunnel Water Treatment Facility (Argo Facility) in Idaho Springs, Colorado uses hydrated lime to produce a high-density sludge with a solids content of 20 to 25 percent and filter cake with solids content from 30 to 35 percent [1]. Furthermore, costs for managing the sludge are significant, approximately $90,000 per year for treating approximately 150 million gallons of water [1]. Although not the case for the Argo Facility, sludge produced from alkaline treatment of ARD has potential to be classified as hazardous. Disposal of sludge also opens up the potential for future liability depending on the sludge’s chemical stability and methods of disposal. In contrast to alkaline treatment, electrochemical treatment produces metals in elemental and other highly-dense forms on the cathode. If metals concentrations and flow rates are sufficiently high, the metals recovered may help offset overall treatment costs. In addition, sludge production would be reduced, if not eliminated altogether, thereby reducing both disposal costs and potential future liabilities as well.

Jan 1, 2019

By Richard H. Lindgren

I appreciate this opportunity to discuss with you OPIC's new policies designed to assist U.S. minerals companies in developing new sources of minerals overseas. A comparison of recent figures on U.S. investment in mineral exploration, development and production gives results which are remarkable --and disturbing. Through the 1960's the flow of U.S. foreign direct investment in mining and smelting in the developed and less developed countries were nearly equal. However, by 1973, roughly 80% of all exploration expenditures by mining companies was taking place in the developed countries and principally in the U.S., Canada and Australia. Clearly it is to the interests of both the developing countries and the United States to put these figures back in better balance. As you may be aware, the administration as a whole is examining systematically what can be done by government to reduce the disincentives and increase the incentives to mineral investment in the less developed countries --the LDCs. A subgroup of the National Advisory Council chaired by the Treasury Department has been formed to coordinate U. S. Government policy and program efforts relating to mineral and energy development in these countries. Among other matters, this subgroup will examine how public policies could positively influence the private investment decision-making process in the minerals industry.

Jan 1, 1978

By L. H. Pye

For large mining sites in the west, the traditional method for performing an ecological risk assessment (ERA) provides little useful information for risk managers faced with selecting and designing sound remedial options. Current U.S. Environmental Protection Agency (EPA) risk assessment guidance largely supports quantitative risk characterization of individual species as surrogates for population and ecosystem-level effects. Developing a work plan for investigating and remediating ecosystem-level changes potentially caused by large-scale historic mining/smelting contaminant release requires a decision process that incorporates a more holistic ecosystem management approach. Some of the most wasteful efforts associated with mine site ecological risk assessments arise when the risk analysis and data collection programs are not specifically linked up-front to the risk manager's decision needs. The following paper discusses the importance of employing a decision-based, ecosystem management framework when conducting ecological risk assessments at large mining sites. A case study of an ecological risk assessment currently being performed at a large New Mexico copper mine site is presented.

Jan 1, 1999

By John J. Bloomfield

Dado que en los últimos quince años se buscó mejorar el stándard de vida de la población latinoamericana, a través no solo de su economía sino de su salud propiamente dicha, es necesario que América Latina repare en el ambiente de la comunidad que vive el trabajador como los demás habitantes. Por tal motivo, el objetivo del texto radica en una evaluación de los riesgos del ambiente del trabajador, como en la legislación social, que suele enfatizar más en la indemnización que en la prevención del mismo. Asimismo, se revisan los 13 trabajos realizados en diversos paises de Latinoamérica, encontrándose que solo 5 tienen un programa efectivo en salud ocupacional. En este sentido, los objetivos del programa de salud ocupacional son importantes puesto que un ambiente de trabajo seguro y saludable donde los empleados cuenten con una salud óptima en la producción industrial, beneficiará a la comunidad y la industria minera, respectivamente.

Jul 20, 1961

By Marco Antônio Siqueira Rodrigues

The possibilities for treating rinse waters fiom chromating bath by electrodialysis are discussed together with the possibilities of optimizing the treatment process for waste reduction and reuse of water and chemical products. An industrial effluent with 4600 ppm of Cr(VI), besides other metallic contamination, was used as work solution. This solution has been recirculated on an electrodialysis cell of three compartments, using exchange membranes Selemiom AMT and CMT. A migration of dichromate ions into the anodic compartment was obtained, so that an extraction of circa 99.9 % of Cr(VI) present on the solution was observed, resulting in water with a Cr(V[) concentration of 4 rnd. These results show that electrodialysis can be used to treat these effluents, and this water could be reused as rinse water. The solution of the anodic compartment, consisting at the beginning of the experiment of H2S04, 0.1 N, reached 7200 mg/l of Cr(VI). This concentrate could be reused on the chromating bath itself.

Jan 1, 1999

By Stephen Simukanga, Jewette Masinja

"Mining has been going on commercially in Zambia for over 100 years. The backbone of the mining industry has been copper production and its by-products of cobalt and gold. Over these years, the mining industry ownership structure has swung from private ownership to state ownership in 1972, and back to private ownership in 1995. Environmental management was first introduced into the body of Zambian legislation in 1991 through the promulgation of the Environmental Protection and Pollution Control Act (EPPCA). The Act’s main functions included the protection of the environment and control of pollution, and in particular to provide for the health and welfare of the people, animals, plants and the environment in general. This Act, was replaced in 2011 by the Environmental Management Act (EMA). The new Act has a number of new elements including: mainstreaming environment in national planning, it provides for the domestication of multilateral environmental agreements, enhances public participation issue, creates a central environmental information depositary, elaborates access to information principles, establishes an environment fund, creates enforcement orders, provides for both Zambia Environmental Management Authority and members of the public to sue for damages following environmental pollution, and provides for the appointment of honorary Inspectors. In addition to this, the Mines and Minerals Act of 1995 provided, for the first time, a section on environmental management in the mining sector. This section also created the Environmental Protection Fund (for mining), and made it obligatory to undertake environmental impact assessment before mining permits could be issued. The Environmental Protection Fund has now been established, as provided for by the law, and currently has more than USD9.0 million in the account. Secondly, environmental auditing is now being carried out annually on mines around the country, the effect of this has been a significant improvement in the environmental management of mining in Zambia. This paper looks at the response of the Zambian mining sector to these pieces of environmental management legislation, and the direction that the mining sector is expected to take on environmental management going forward."

Jan 1, 2014

By William J. Miles

The markets and applications of Wyoming bentonite deposits are primarily determined by the functional properties of a bentonite ore which results from the unique mineralogy and chemistry of each deposit. Commercial bentonite products contain sodium montmorillonite as the major mineral component, with minor concentrations of accessory minerals such as quartz, opal (silica hydrate), mica, feldspar, gypsum and zeolites. The chemical composition of the sodium montmorillonite influences the functional properties of the bentonite in significant ways. The type and concentration of various accessory minerals also influence the acceptability of the bentonite in each market.

Jan 1, 1995

By Elbasher M. E. Ahmed, Indresan Govender

"A mechanistic model of axial charge segregation in rotating drums is presented. We show that granular material composed of different frictional properties diffuse into axial bands as a consequence of concentration fluctuations in the free surface layer that is caused by friction-limited mobility. A Bagnoldian stress assumption ensures an asymmetric free surface profile thereby providing the essential ingredients for the evolution of axial bands and the subsequent band coarsening observed in the literature. The formulation is sensitive to the boundary conditions of tumbling mills, including particle size and density, mill speed, inter-particle bulk friction, end wall friction and drum geometry (length and diameter).INTRODUCTIONA mechanism to fully describe the axial segregation of charge in a rotating drum remains elusive to the mineral processing industry. With regard to low aspect ratio mills (like ball mills), current thinking favours the use of closed circuit mills with correspondingly low residence times to offset the completely random contact probabilities between particles and balls (Wills & Napier-Munn, 2006). Conical end caps are argued to exploit the centrifugal force to achieve a regular gradation of ball size along the mill with larger sizes at the feed end and smaller ones closer to the discharge. However; segregation along the length has been observed in the absence of conical end caps (Oyama, 1939; Levine, 1999): In these investigations, sufficient differences in the particle’s mechanical properties (particle size, density, shape, surface roughness) was enough to successfully achieve axial segregation. Figure 1 shows the segregation of a bimodal distribution (by size) into bands of larger (darker colour) and smaller (lighter colour) particles."

Jan 1, 2016

By Luis Ramirez Grados

El presente texto examina los problemas de diseño que se presentan en el sistema de minado subterráneo debido a su interrelación con los variados escenarios geológicos. Para ello, se cita el ejemplo del acarreo de desmonte y mineral de la Estación de Carguío H-2 del Nv. 2430 de la Rampa RNG 92442 @ -15% hacia el echadero de desmonte y la Tolva de Mineral de la Planta Concentradora en superficie Nv. 2765, donde el sistema de acarreo fue modelado usando simulación, la cual fue utilizada para ver la rentabilidad del sistema scooptram-volquete.

Sep 14, 2009

By K. Soucek, J. Ptácek, A. Hastíková, R. Kukutsch, P. Konícek, P. Waclawik

"Cable bolts are used frequently as a secondary support system (with steel arch support) in difficult stress-strain conditions of deep coal mines. The load transfer mechanism of cable bolts depends on several factors, such as the strength, deformation and geometric properties of the bolts, resin and the surrounding rock mass so-called cable-resin-rock system (CRR system). The bonding length and bolt/borehole diameter ratio strongly influence the final bearing capacity of the CRR system.The study presents the behaviour of CRR system during a pull-out test which is usually used in the carboniferous rock mass in the Czech part of the Upper Silesian Coal Basin. A series of 28 pull out tests were performed on 3-m-long cable bolts, with various combinations of borehole diameters and bonding lengths, to understand this behaviour. Boreholes were drilled into a solid rock mass consisting of fine-grained sandstone to guarantee similar conditions during the pull-out tests. Video inspection and measurement of borehole diameters were performed to determine their quality and real diameters. Three characteristics were observed from pull-out test results: ultimate pull-out load; displacement of the end of bolt and system stiffness. Numerical modelling by FEM (Finite Element Method) was used to determine the stiffness of the CRR system for variable bolt/borehole ratios and bonding lengths each under constant load. A linear elasto-plastic model and a mohr-coulomb model were used for cable and resin-rock respectively. The results of the experiment may contribute significantly to improving of the methodology of cable bolts installation as well as the design of used cable bolts."

Jan 1, 2015

By David F. Gearhart, Khaled M. Mohamed

"Trusses are primarily used as passive roof supports in coal mines. They are constructed of three main parts: two grouted bolts installed at opposing forty-five degree angles into the roof so that they are anchored over the ribs and a cross member that ties the angled bolts together. There is also hardware used to assemble these components. The capacities of the angled bolts are typically 30 to 40 tons and the tensile capacity of the cross member is also 30 to 40 tons. Importantly, the direction of the immediate roof loading on the cross member is unlike the direction of the loading on the angled bolts. The load on the cross member is transverse to the longitudinal axis instead of along it, and therefore the cross member is loaded in the weakest direction.Previous tests conducted on truss systems applied loads such that the increasing tension in the two diagonal bolts increased the tension in the horizontal cross member, resulting in a stiff response. By contrast, if the load is applied directly to the cross member, which then transmits those forces to the diagonal bolts, it results in a much softer response.Based on this difference, laboratory tests to apply transverse loads and measure the vertical load capacity of three different types of cross members were conducted using the Mine Roof Simulator (MRS) located at the National Institute for Occupational Safety and Health (NIOSH) in Pittsburgh. The length of the samples was about 16 feet. Single-point load tests, with the load applied in the center of the specimen were conducted to verify the performance of the test arrangement and the finite element models. Double-point load tests, with a span of eight feet, were also conducted. This arrangement replicates the performance of the cross members with a distributed load. Both of these test arrangements were conducted on one-inch-diameter threaded steel bars and 0.7-inch-diameter cable and 0.6-inch-diameter cable cross members.For the single-point load configuration, the yield of the one-inch bar was nominally 22 kips of vertical load, achieved at 17 inches of deflection. For both sizes of the cable cross members, yield was not achieved even after 18 inches of deflection. Peak vertical loads were about 20 kips for the 0.7-inch cables and 15 kips for the 0.6- inch cables. For the double-point load configurations, the one-inch bar cross members yielded at 33 kips of vertical load and 10 inches of deflection. The 0.7-inch-diameter cable cross members broke strands at 30 kips of vertical load and 10 inches of closure, and the 0.6-inch-diameter cable cross members broke strands at 25 kips of vertical load and 10 inches of closure. Finite element models of each of the six different configurations were developed and show the variation of the vertical capacity of the cross members and the difference of the behavior of the bar versus the cables."

Jan 1, 2015

By Jia Ma, Lu-De Qiang, Zhi-Chao Liu, Chun-Feng Li, Guang Li, Bao-Bin Tang

"At present, research on the surface chemical properties of uranium minerals is very scanty, which restricts the research progress of uranium ore flotation process research. The research aimed at exploring the surface characteristics of two common uranium minerals and providing basis for flotation process to enrich uranium minerals in ore. This paper selected pitchblende and uraninite as the object of study, which are widely distributed in uranium deposits. We chose out the pure minerals of pitchblende and uraninite from different ores collected from different uranium deposits. By means of Zeta potential test and X-ray photoelectron spectroscopy (XPS) test, a preliminary study on surface characteristics of the pure minerals of pitchblende and uraninite was conducted. And the significance of the change of Zeta potential, the elements composition and valence state on the minerals surface for flotation was discussed. The research shows that, the Zeta potentials of pitchblende and uraninite in pure water are negative mainly when the pH value varies from 2 to 11, which maybe a result of the difference of ionization capacity between two kinds of oxy-compounds on the surface of minerals. On the surface of pitchblende and uraninite, the metal elements are mainly U, Th and Pb. U is mainly in the form of UO2, Th is mainly in the form of ThO2, and Pb is mainly in the form of Pb and PbO. Based on the surface characteristics of pitchblende and uraninite, we can select process and reagents appropriately in uranium ore flotation.INTRODUCTION Globally, the major challenges associated with exploitation of low grade ores are about finding economically feasible processes for reducing the mass of gangue minerals (Filippov et al., 2012). Among the beneficiation technologies of low grade uranium ores with complex minerals assemblage, flotation is the common process which is used to reduce production cost and eliminate the acid-consuming minerals (Li et al., 2016; Liu et al., 2015)."

Jan 1, 2018

By B. W. Gandrud

In 1927 Coghill showed that there is considerable liberation of the iron oxide mineral from gangue when the Alabama red iron ores are ground to a size suitable for classification and tabling but that there is not sufficient to make possible a high extraction and a high grade of concentrate. Coghill states: High extraction and 'high grade of concentrate cannot be obtained without grinding to a size comparable with flotation or cyanide practice. If grade of concentrate be sacrificed the grinding need not be so severe. These ores slime readily during grinding, and in most instances the slimes are only slightly higher grade than the original ore. Not only do they carry a considerable percentage of the total iron in the ore, so that to reject them as tailings would result in prohibitively low extraction, but they are too fine to be amenable to ordinary methods of gravity concentration. In 1929 the Bureau of Mines published results showing that certain Alabama oolitic iron ores could be concentrated by classification and tabling after grinding, with rubber-covered rods. This selective grinding produced slimes of much higher grade than the original ore, and they were considered part of the final concentrate.

Jan 1, 1934

Federal Regulations require that coal producers conduct a written, in-house investigation with every lost time injury accident. Besides their obvious value in accident prevention, competently conducted investigations can provide a number of additional benefits to include positive supervisor involvement, the control of rising worker's compensation costs and a measure of protection from civil/criminal proceedings. The paper describes such topics as MSHA minimum requirements, investigator selection and training, accident site procedures, witness interview techniques and the management review process. The reader is also presented with a number of information resources available through MSHA, the National Safety Council and other sources.

Jan 1, 1995

By S. C. Sun

The grinding of coals for coal preparation has been studied extensively by previous investigators, but no similar work has been done on coal lithotypes (l-4). However, the different natural breakage characteristics of coal lithotypes have been recognized and utilized by the coal industry (5,6) to develop the Longway Burstlein process (7) for the concentration of macerals(8). The specific objective of this research was to determine the relative grindability of lithotypes, obtained from both anthracite and bituminous coals. An attempt was made to relate the findings, wherever possible, to the chemical and physical properties of the tested lithotypes. Another aspect of this research was to ascertain the size distribution and grindability of lithotypes ground at a various number of revolutions in a Hardgrove mill.

Jan 1, 1970

By E. L. Tucker

PREVIOUS investigations of E. L. Tucker and R. E. Head' related in particular to the effect of cyanogen compounds on galena, sphalerite, and pyrite, and their behavior in the presence of such com- pounds. The present contribution deals with the float- ability of the copper minerals and of pyrite. All experiments were performed on minus 200-mesh material, the method of preparation being the same as that described in the previous article. Flotation tests were made in a small mechanically agitated machine of 50-g. capacity designed in this laboratory by Gates and Jacobsen." General Naval Stores pine oil No. 5 and potassium xanthate were used in constant amount in all of the experiments; these agents were selected because of their present wide use in the flotation of copper minerals. Lime additions were varied to secure four 'final hydrogen ion concentrations, namely, neutral, 0.0005 per cent CaO, 0.003 per cent CaO, and 0.02 per cent CaO. The variation in lime addition was introduced to include the range of alkalinities employed in actual flotation practice.

Jan 1, 1926

By Luan Bezerra Silva

O presente trabalho pretende estudar o comportamento mecânico do cobre eletrolítico C11000 e da liga de cobre cromo C18200. Esses dois materiais são objetos de estudos da equipe técnica que está desenvolvendo a câmara de combustão do motor foguete propelente líquido L75. Atualmente, não há disponível na literatura informações sobre o comportamento mecânico desses materiais em altas temperaturas. A fim de suprir essa necessidade, foram realizados ensaios de tração a quente, no intervalo de temperatura de 27 a 500°C. Adicionalmente, foram realizados ensaios de dureza Vickers e metalografia para avaliar a capacidade do material em resistir mecanicamente em altas temperaturas. Os resultados obtidos demostraram que o cobre eletrolítico sofre amolecimento a partir de 400ºC e que o cobre cromo, apesar de apresentar elevada resistência mecânica quando comparado com o cobre eletrolítico C11000, é um material frágil.

Aug 16, 2017

By Paulo Rogério Minatto

A corrosão provocada pelo CO2 associada ao tipo de escoamento é uma das mais agressivas ao aço de baixo carbono o API X65. O petróleo extraído do pré-sal de baixa profundidade apresenta maior concentração de CO2 podendo aumentar os pontos de corrosão nos equipamento e nas tubulações. O dióxido de carbono sendo um óxido ácido em contato com a água forma o ácido carbônico que reage com o metal formando camadas protetoras de óxidos ou de carbonatos. Essas camadas que ficam entre o metal e o fluído tendem em alguns casos atuarem como protetoras, mas à medida que aumenta a intensidade do fluxo essas camadas podem ser rompidas formando novos pontos de corrosão. As indústrias petroquímicas estão investindo em novos processos de perfuração e no desenvolvimento de novas ligas metálicas que possam conter a corrosão provocada pelo CO2 nos equipamento e nas tubulações que transportam o petróleo e seus derivados. Este trabalho tem por objetivo caracterizar a taxa de corrosão por CO2 em condições de fluxo do aço API X65, nas condições normais de temperatura e pressão, utilizando uma bancada de ensaio dinâmico (loop). Mantendo a concentração constante de CO2 em solução aquosa de NaCl 1% foi monitorado o pH, a temperatura e a concentração de íons ferrosos na solução. A taxa de corrosão foi determinada pela perda de massa, estabelecida após os ensaios. Como conclusão observou-se que CO2 provocou uma maior perda de massa para as amostra com maior rugosidade.

Aug 16, 2017

By A. Golder, I. Roy

The Jayant opencast operation is one of the largest opencast coal mines in India. Prior to 2008 the mine experienced a number of dragline dump failures, which was a major hindrance in sustaining production. Northern Coalfields Limited (NCL) and the mine management engaged several design, research, and academic institutions to carry out dump slope stability studies, particularly of dragline dumps. BirlaInstitute of Technology prepared a report on the investigations in May 2009. In this paper we review the findings of the report and the measures taken to tackle the safety aspects of dragline dumps.

Jan 2, 2022

By H. J. C. MAC DONALD

THE mining engineer must have a chest of books snug enough for a camelback or to be stowed away in a canoe; at the lowest possible cost, as he needs it the most in those early years when he earns the least; but at the same time one having an unusually wide range, for he may have to cut down a forest, put up a sawmill, build mine towns, construct dams, power houses, power lines, and railroads. In fact he may be called upon for many unexpected accomplishments and all in extension of the characteristically broad demands of his profession. Suppose that an average mining engineer with a thorough theoretical training and a specialized mining education has accumulated, during a cosmopolitan experience, a complete and up-to-date library, but, unfortunately, in accepting a long term assignment to a far country he is forced to discard the greater part of

Jan 1, 1925