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By Kraig W. Grubaugh

Rapid growth in the rate of surface mining for coal has caused many states to increase the rigor and complexity of their surface mining codes. The promulgation of Federal surface mining standards may cause those states containing Federal land to amend their codes also. Presented is an up-to-date review of these codes with tabular summaries that divide the codes into operative functions. These summaries will be of use to new operators, multiple-state operators, and state officials. Suggestions are made for industrial efforts to present workable and acceptable amendments to these codes.

Jan 1, 1977

By P. I. James, M. R. Baker

Este artículo analiza la nueva producción de cobre a partir de "minerales de desecho" de baja ley usando la tecnología de Blue Planet Strategies DEMET™ (Dynamic Electrode Mining Effluent Treatment, por sus siglas en inglés), que tiene como objetivo salvar la brecha de procesamiento entre la solución débil de lixiviación en operaciones de extracción por solventes/electrowinning (SX/EW), removiendo electroquímicamente los metales a partir de corrientes débiles y a la vez generando productos concentrados en metales objetivo en un análogo funcional de extracción por solventes (SX). Se estudió el tratamiento de la débil solución de lixiviación pregnant (PLS por sus siglas en inglés) y se usó para estimar los impactos económicos y de producción para una hipotética lixiviación en pilas de cobre brownfield y una operación aumentada DEMET usando SX/EW para tratar el "mineral de desecho." Se presenta la remoción de cobre a un 86% de eficiencia en las placas por debajo de 0,1 g/L de cobre con un consumo de energía de 0.55 kWh/lb de cobre y una concentración del producto mayor a 10 g Cu/L. El modelamiento arrojó aproximadamente $2/ lb para la producción total de cobre y costos de tratamiento menores o iguales a $1/lb con un inmediato aumento del margen bruto de operación del 12% para el brownfield incrementado. Se indicó también un aumento de la vida de la mina con un margen bruto promedio de 38% en la producción aumentada de "mineral de desecho" con valores de cobre de $3.25/lb.

Jan 1, 2014

By R. O. Ifill

Alternating current electrocoagulation (AC/EC) may be an alternative to chemical coagulation in the thickening of tailings in the mineral, coal and petroleum industries. In the current study, ground silica (d50 as received, 20 µm) served as the model tailings solid with characteristically poor settling behavior. Its natural initial settling rate was 1.6 x 10-3 cm/min. This paper discusses the indirect application of AC/EC via aluminum electrodes to the enhancement of the settling behavior of the silica. ?Indirect AC/EC? means that the silica was coagulated upon dispersion in water that had been treated by AC/EC. The effect of AC/EC retention time on settling behavior is examined and the water chemistry is analyzed. Test results show that the initial settling rate of silica was enhanced by a factor of 4,000 at its maximum of 6.4 cm/min, under the conditions employed. Settling enhancement was achieved upon contact between the AC/EC-treated water and the silica, and the enhanced initial settling rate was dictated by the floc size. The aluminum dosage increased with AC/EC retention time, reaching a maximum concentration that was equivalent to 13.1% of that predicted by Faraday?s law. Complex aluminum ions are considered to have adsorbed onto the silica surface and an adsorption mass ratio of 0.3 mg Al/g silica was the most effective in enhancing settling behavior. Owing to pH change or slow kinetics, aluminum hydroxide precipitation did not lower the ion product ([Al3+][OH-]3) below the KSP of 6.3 x 10-32.

Jan 1, 2011

By Liming Yuan, Isaac Zlochower, RICHARD THOMAS, Thomas H. Dubaniewicz, Teresa Barone

Mining vehicle manufacturers are developing lithium-ion (Li-ion) battery electric vehicles as an alternative to diesel-powered vehicles. In gassy underground mines, explosion-proof (XP) enclosures are commonly used to enclose electrical ignition sources to prevent propagation of an internal methane (CH4) air explosion to a surrounding explosive atmosphere. Li-ion batteries can create pressurized explosions within sealed enclosures due to thermal runaway (TR). Researchers at the National Institute for Occupational Safety and Health (NIOSH) measured TR pressures of lithiumiron phosphate (LFP) cells as a function of free space within sealed enclosures and observed an inverse power relationship. A well-confined cell produced 294 bar (4260 psia) of pressure during a TR, far exceeding minimum pressure containment specifications for conventional XP enclosures. Results indicate that adding enough free space surrounding LFP cells can reduce TR pressures to levels below that expected for CH4-air ignitions. Measured TR temperatures were below the minimum autoignition temperature of CH4-air.

Nov 6, 2020

By Yongjun Xian

The release of fluid inclusions has a strong potential for the unintentional activation of pyrite during flotation. The present study aims to characterize fluid inclusions in a natural pure pyrite. The results indicate that a certain amount of fluid inclusions exist in the pyrite. The fluid inclusions assume a variety of shapes, including long strips, oval shapes and irregular shapes, with sizes that range from a few microns to dozens of microns. From the EDS results of hollow positions that resulted from the fracture of the fluid inclusions on the pyrite surface, certain amounts of Al, Cr, C, O, Ag and Cu were clearly detected; these elements were not detected in FeS2 pyrite itself. The contents of the inclusions were released into solution when the sample was subjected to a grinding process. Under experimental conditions of 2 g of pyrite cleaned in 40 mL of pure deionized water under an inert atmosphere, the concentrations of Cu, Fe, Cl- and SO4 2- released from the inclusions reached concentrations of 3.29 × 10-6, 32.52 × 10-6, 51.57 × 10-6 and 75.90 × 10-6 mol/L, respectively. These values are significantly greater than those from the experimental nonoxidative and oxidative dissolution of the pyrite. The fluid inclusions of pyrite were, therefore, concluded to represent the dominant sources of Cu, Fe, Cl- and SO4 2- in the aqueous solution. The present investigation provides a new understanding of the source of the unavoidable metal ions in the pulp and may benefit understanding of the flotation theory and environmental geochemistry.

By R. Herrera-Urbina

Measurements of the electrophoretic mobility of bastnaesite in aqueous solutions of sodium nitrate reveal that the isoelectric point (iep) of this cerium fluocarbonate occurs at about pH 9.3. These results also indicate that the pH affects significantly the electrophoretic mobility of bastnaesite, which becomes more positive as the pH decreases and more negative as the pH increases from the iep. Computations of solid-solution equilibria for the bastnaesite-H2O system closed to the atmosphere as a function of pH indicate that cerium fluoride precipitates in acidic solutions, whereas cerium hydroxide precipitates in alkaline solutions. When the initial amount of bastnaesite is fixed at 0.05 wt.% (the solids concentration used for electrokinetic experiments), these computations reveal that bastnaesite is the only solid phase in the pH range from 5.75 to 8.55, it coexists with CeF3(s) between pH 5.22 and pH 5.74, and with Ce(OH)3(s) between pH 8.56 and pH 10.12. Cerium fluoride and cerium hydroxide are the only solid phase below pH 5.2 and above pH 10.2, respectively. According to these computations, the dissolution-precipitation processes that occur when bastnaesite is equilibrated in aqueous solutions at different pH values determine the solid phases present in the system. In turn, these processes must affect the electrokinetic potential at the solid-solution interface, and they must be considered for explaining electrokinetic measurements as a function of pH when bastnaesite is the original solid phase in aqueous suspensions.

By M. Westerstrand

The processes involved in the concentration of magnetite ore with process water as the aqueous medium can have a strong influence on the surface properties of the magnetite particles. In this study, different leaching methods, as well as zeta potential measurements, were used to examine the major easily accessible ions on the particle surfaces and their effect on the surface charge. The results show that the enrichment of elements on the surface of the particles appears early in the refinement process. Ca was enriched up to 15 times and Si up to 50 times compared to what pore water alone would have given. The leaching experiments also showed that the addition of water glass increased the surface enrichment of Si and that the collector might hinder desorption of Ca. An alkali leaching method was evaluated, which showed that Si was much more enriched than S and Cl. Zeta potential measurements on synthetic magnetite particles showed that process water resulted in zeta potentials different from the potentials measured for these particles in aqueous calcium and silicate solutions. Therefore, it is important to consider the complexity of the process water when making predictions about the properties of the particle surfaces in the final magnetite concentrate, which most studies do not. Zeta potential measurements were also used to rule out a strong influence from organic matter in the process water on the magnetite zeta potential.

By Jacques B. Wertz

Recurring movements remotely connected with the Murray fracture zone and the San Andreas fault complex, together with the slow northwestward drift affecting the Baja California peninsula, could progressively have accentuated the tensional situation already connected with the anticlinorium in southern Arizona. From the fragmentary data gathered on the Texas lineament, it appears that a very mild curvature, concave to the northeast, may be present along this belt throughout Arizona. Those localities where the successive changes in direc¬tion of the strands of the lineament belt seem to occur do generally coincide with intersections of both north-northwestern and northeastern breaks. It is along the outward, southern fringe of the belt (at such structural centers like Bisbee, Baboquivari, Ajo) that the greatest impact of regional movements could be expected to have occurred through tangential-torsional stresses. Although it si accepted that the north-northwestern and more particu¬larly the northeastern fractures in Southeast Arizona are propitious to or partially responsible for mineralization, it seems undeniable that the Texas lineament belt must have greatly increased the potentialities for ore throughout the Arizona copper province. While intrusive bodies occur near major intersections, with the Texas lineament belt as a common denominator, it seems, the ore deposits are to be found close to one of the intrusive stocks, varying in distance from contiguity (Bisbee) to one or two miles away (Silver Bell orebodies).

Jan 1, 1970

By C. Okrusch, C. Roos, M. Akers, S. Rosenthal

Modern mining consistently faces controversy. Public sentiment impacts the permitting and development of mines, so a quality public relations (PR) program for mining companies may improve society’s impression of the mining industry. Developing mines face more permitting challenges than operating mines, which stems from a lack of societal trust given the history of mining and its impact on the environment. Two case studies were selected based on the type of public controversy they face to demonstrate how pervasive permitting issues are in industry. Both Pebble Mine, owned by Northern Dynasty Minerals (NDM), and Black Butte, owned by Sandfire Resources America Inc (SRA), experienced difficulties with their water permitting due to potential risks their mine developments posed to local fish populations. Pebble has, to date, failed in all of their attempts to become permitted due to concern for the water and the fish. Black Butte dealt with the same problems, on a smaller scale, but was able to become permitted. These two mines will be discussed in detail including local history, mine setting, mining history in America, prevalent culture groups, technology development, and intercultural communication competence (ICC). The mining industry needs to evaluate its ICC skills since ICC directly determines the effectiveness of PR. Based on Barna’s Stumbling Blocks for intercultural communication, methods for improving the mining industry’s PR will be suggested in the hope of easing the permitting process for future mines by developing ICC.

Mar 2, 2022

By S. D. Hill, G. E. McClelland

To maximize productivity and improve minerals processing technology, the U. S. Department of the Interior, Bureau of Mines, is investigating a particle agglomeration technique as a means of increasing the percolation rate of leaching solutions through heaps of clayey or finely crushed, low- grade, gold-silver ores. Bench-scale and pilot-scale experiments conducted on different ores indicated that the percolation rate of cyanide leaching solution was enhanced markedly by mixing the ore with a binder, such as lime or portland cement, moistening the mixture, then mechanically agglomerating and aging the feed prior to heap building and leaching. In addition, the rate of silver and gold extraction markedly increased without sacrificing total recovery of values. The use of concentrated cyanide solution instead of water during the agglomeration procedure substantially decreased the leaching time required to obtain maximum recovery. Results from bench-scale and pilot-scale experiments using the particle agglomeration technique are discussed.

Jan 1, 1981

By Furuyama Takashi, Mori Sukeyuki, Hara Tsuyoshi, Fukushima Yujin

In mineral processing practice, flocculation is largely established as an engineering technique of waste water treatment and the study of parameters increasing the settling velocity of particles is still of great importance to improve the process. Further investigations were made using quartz (Q89) and fluorite samples (F91) which included 58.8% and 65.8% of -2.3 µm particles respectively. In all the experiments the flocculation phenomena were observed varying the pH value of the aqueous suspension. In contrast to quartz particles (Q89) which did not flocculate for all pH values, it was, noticed that fluorite particles (F91) flocculated in the alkaline range of pH over 11. With an aqueous suspension containing equal quantities of Q89 and F91, a hetero-flocculation of particles was observed at a range of pH below 10. In this case, the maximum floc size of the hetero-flocculation was 37.0-26.2 µm This size was about three times larger than when quartz (Q84) and fluorite particles (F85) were used with 32.4% and 40.4% of -2.31 µm particles respectively. Besides, in the experiments using Q89 and F91, the maximum size of hetero-flocculated single particles was found to be 6.54 µm instead of 3.27 µm as obtained with Q84 and F85.

Jan 1, 1995

By C. N. Savage

An industrial minerals review involves an attempt to assemble field and statistical data which are obscure, elusive and incomplete. Often, when me statistical data are available, combining or lumping of commodity values conceals the value of specific items. Personal knowledge of the minerals known to occur in the area of concern, combined with whatever available published data may be compiled, together with careful use of several extrapolation methods, may yield an acceptable summary review of the industry. However, it is particularly hazardous to speculate on future trends and economic aspects because of the many unpredictable variables which may affect the industrial minerals business. Among these variables are the effects of diverse geological conditions, the impact of technological changes (including new uses for minerals not formerly considered industrial types), changing socio-economic factors (including growing environmental controversy), use of substitutes and even recycling of some of the industrial minerals (for example, building materials, lime, etc.). My main objectives are to reveal, as accurately as I can, the state of the in¬dustrial minerals situation, and the effects of possible future developments on this industry in Idaho. Where the words...industrial-tyke minerals, .are used in this discussion, reference is made to selected metallic and nonmetallic minerals and related materials, as well as rock (Table I). Industrial minerals known to be present in Idaho may be listed under general use categories as in Table 1. Some of these commodities are being marketed, have been marketed in the past, or occur in potentially marketable quantities. Mineral fuels are neither mentioned, nor are they considered important in Idaho. Based upon our present knowledge and lack of known, economically valuable occurrences of these commodities, they are considered insignificant (Idaho Bur. Mines and Geology, 1964). Information used for this study is from several sources. Most of the statisti¬cal information should be credited to the U.S. Bureau of Mines Minerals Yearbooks,

Jan 1, 1971

By Sheridan A. Glen

As the Federal government along with individual states continue to grapple with the job of refining a comprehensive energy policy, coal continually stands out as an energy source which heralds a combination of old and new capabilities like an energy planners prophecy, but which is plagued with serious environmental constraints. To determine what level of coal utilization is ultimately possible for states East of the Mississippi, whose high sulfur content coal presents the most paramount of challenges, one must consider product availability, via existing transportation modes, the developing industrial markets and the ability of coal to meet the challenge of becoming an environmentally acceptable fuel. Gasification is emerging as a form of utilization, which during the next twenty years stands a good chance of being able to meet the challenge of making coal an environmentally clean, easily transport-able and usable fuel. It can be argued that, of all the potential ways of utilizing high sulfur coal, coal gasification is perhaps the most expensive, the most financially risky and carries environmental liabilities of its own. Synthetic gas and oil markets will undeniably be a function of price and demand, which, for the purposes of this paper, I'm assuming will begin to merge in the late 1980's and into the 1990's. This is also presuming that public utility commissions will allow favorable price structure ruling so that gasified coal products can be rolled into their respective rate base, much the same as synthetic natural gas from petroleum by-products are currently being priced. The comparative economic markets of coal to gas pro-duct have plenty of time to mature. There is an approximate twelve-year lead time needed to bring coal gasification plants on line which will be able to compete in the market place for natural gas and oil customers.

Jan 1, 1977

By Jay F. Colinet

Coal workers’ pneumoconiosis (CWP), commonly known as black lung, is caused by the inhalation of respirable coal mine dust and is a disabling and potentially fatal lung disease with no cure. Historically, CWP has taken a tremendous human and financial toll in the US coal mining industry. Recent health surveillance data indicates that CWP continues to occur at elevated levels. Respirable coal dust exposure must be controlled to prevent the development of CWP. The Pittsburgh Mining Research Division of the National Institute for Occupational Safety and Health (NIOSH) conducts laboratory and mine-site research to identify control technologies that can be used to successfully reduce respirable dust levels. Various technologies, using multiple methods of control, can be applied in order to reduce dust levels. An overview ofCWP’s impact and a general methodology for controlling respirable dust in underground coal mines are discussed in this paper.

Jul 30, 2020

By L. Yan, B. Lambie, J. Srednicki, J. Carr

Electromagnetic emissions from electrical devices may interfere with electronic safety systems or other devices in the mining environment. This electromagnetic interference (EMI) may cause unwanted changes in the performance of the affected devices and may cause safety issues for miners. To minimize the risk of EMI, the National Institute for Occupational Safety and Health (NIOSH) has conducted research quantifying the electromagnetic emissions of several types of equipment that might be used in the mining environment. Previous research has shown that welding arcs can give off ultraviolet (UV) emissions, visible light, and infrared (IR) emissions that can cause health problem on skin and eyes. In this study, the electromagnetic emissions of the shielded metal arc welding (SMAW) process were monitored and measured. Several factors including operating mode (AC, DC positive or DC+, DC negative or DC-), current setting (low, medium, high, maximum), and electrode type were investigated to compare their effect on emission level. The test shows that the emission level from the welding process can be affected by those factors. The test data also shows that, among those factors, the operating mode has more influence on emission level than do current setting and electrode type. The information in this paper can be useful for the mining industry to better understand the emission in the 9-kHz to 500-MHz frequency range from a SMAW welder.

Feb 1, 2023

By A. Eccles

Phase designs are the foundation upon which all open pit mine sequence optimizations and budgets should be built. Unfortunately, at times, mine engineers skip the step of developing realistic pit phase designs - designs that include access ramps and mineable widths. Without mineable phase designs, their optimized schedules are based on theoretical pit shells or ?quick-and-dirty? plans with no ramps. The output from such optimizations is almost always overly optimistic. Without mineable designs, the production estimates are misleading, because they overestimate ore, and underestimate waste stripping requirements. Worse yet, when plans are not based on realistic phase designs, they can point to exactly the wrong decision in feasibility studies (i.e. ?go? when it should be ?no-go?). This paper discusses the importance and features of good pit phase design, and demonstrates the pitfalls of relying on optimized production sequences that are not based on properly designed pit phases.

Feb 27, 2013

By A. López-Valdivieso, M. A. Corona-Arroyo, M. Llamas-Bueno

Magnetite (Fe3O4) ore is concentrated by low-magnetic-field drums to recover a magnetite concentrate that is low in silica (SiO2). The presence of SiO2 in the magnetite concentrate for steel production increases the steel processing costs, so a major challenge in magnetic concentration is to lower the SiO2 grade in the Fe concentrate. This work presents studies that were carried out on the removal of SiO2 from the magnetite concentration at the plant scale. Studies were performed with a three 36 × 96″ drum unit processing 46 ton/h of rougher magnetite concentrate. These studies showed that silica appears in the magnetite concentrate by three mechanisms, namely SiO2 entrainment in Fe3O4 chains, heterocoagulation between Fe3O4 and SiO2 particles, and mineral locking of SiO2 to Fe3O4. The SiO2 entrainment mechanism had the highest contribution (75%) to the SiO2 recovered in the Fe concentrate. Electrokinetic studies on Fe3O4 and SiO2 showed that heterocoagulation occurs because of the low negative zeta potential of the minerals at the pH of the plant slurry. This study also showed that a high percentage of ultrafine size SiO2 particles trapped in Fe3O4 agglomerates was not removed by the dilution water for the slurry fed to the drum. To lower the SiO2 recovery in the drum magnetic concentration process, work should be directed towards the removal of trapped SiO2 in Fe3O4 agglomerates.

By B. R. Stewart

The exclusion of coal fly ash from regulation as a hazardous waste has led to increased interest in returning ash to the coalfields for co-disposal. A multi-year column study used coal refuse with high potential acidity (4% total-S), and two alkaline ashes in various bulk-blends. The unamended refuse acidified rapidly, producing acidic (pH 1.7) leachates, high in dissolved metals. Treatments blended with sufficiently high amounts (20 to 33%) of alkaline ash produced alkaline (PH >8.4) leachates with low metal levels, while lower ash blending rates acidified over time to produce metalliferous leachates. Examination of solid materials indicated that pyrite oxidation was occurring to some extent in all treatments. A regression equation (r = 0.95) was developed to estimate time to net acid release for mixtures of these materials. Ash alkalinity and refuse potential acidity must be balanced to insure water quality for co-disposal environments, or the ash materials should be isolated away from acidic drainage waters.

Jan 1, 1997

By Craig Hartley

? A helper stands beside a continuous miner as the operator is at the controls. The operator means to push the stop button but hits the drum rotation start button by mistake. The drum begins to turn and the bits catch the helper's clothing. He is thrown violently to the ground and suffers multiple contusions. ? A farmer's wife helplessly watches her husband drawn into the claws of farm machinery while she frantically and unsucessfully searches for the control to stop the machine. ? A mechanic on the night shift replaces plugs in the lubrication systems of all three engines of an airliner following routine maintenance. In doing so', he fails to notice that "0" ring seals have not been mounted on the plugs. A few hours later, as the fully loaded airliner is cruising high over the ocean, oil pressure on one engine drops precipitously. The pilots quickly shut down the engine and turn for home. Almost immediately, the two remaining engines lose their oil and fail.

Jan 1, 1983

By Joseph D. Drew

Oregon Resources Corp. (ORC) has developed and permitted a new mining operation that incorporates a process design that will allow the unique paleo-beach placer deposits of southwestern Oregon to be extracted efficiently and economically, creating the only domestically mined source of a unique foundry grade chromite and specialty de-veining sand for precision casting. The operation will also provide an additional domestic source of garnet and zircon. Engineering design has been guided by the variable geology and mineralogy of the paleo-beach placer deposits as well as the need for a dry tailing scheme that resolves a lack of water resources at the placer locations and at the same time eliminates the need for slurry settling ponds, typical of paleo-beach placer operations in North America.

Jan 1, 2010