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By J. A. Barsin

Stationary air pollutant sources established prior to the New Source Performance Standard (NSPS) are not, at present, subject to federal emissions regulations. However, proposed legislation could require many existing stationary sources to reduce emissions. This paper will report upon the laboratory work undertaken to date by B&W to commercialize a limestone system for sulfur capture both in pulverized coal and cyclone coal-fired utility boilers. Updates will be provided on the US EPA/State of Ohio/Ohio Edison/B&W sponsored pulverized coal full-scale limestone injection demonstration, and on the EPRI/Baltimore Gas 8 Electric, Atlantic Electric/B&W sponsored laboratory-scale cyclone coal limestone injection investigations.

Jan 1, 1986

By G. Bourque

Early in the design stage of their new concentrator for the Mount Wright Plant, Quebec Cartier Mining decided to use a process computer for total control of crushing, grinding and concentrating. A map of the area is given in figure 1 and a view of the plant in figure 2. Although the use of process computers is not a new idea in petrochemical and chemical industries, their use in the mining industry is very limited. We innovated in using the computer, not only for data logging, as we have seen in some other plants, but a sole operator located in the administration building, starts and stops mill lines, crushers, load-out system, tailings, thickeners, etc ... by means of a CRT console. Our process is fairly simple as can be seen on the schematic process flow diagram (figure 3). .The ore, carried by 136t diesel electric trucks, is dumped through ore pockets onto two primary pan feeders. The feeders supply two 1,52mx2,79m gyratory crushers which reduce the ore to minus 20,32 cm. Each crushing line have a capacity of 5600t per hour and feed a shuttle conveyor distributing the crude ore into six silos.

Jan 1, 1979

By D. Royston

Gold ores containing antimony suffer from poor recoveries of gold in cyanidation due to the impact of antimony on the cyanidation process. Techniques such as lowering the pH for cyanidation can improve gold recovery, nevertheless a limit can be reached where high cyanide consumption makes traditional processing uneconomic. The paper outlines a process for the pre-treatment of gold-antimony concentrates to remove the antimony resulting in a low-antimony content gold-bearing residue suitable for efficient treatment for gold recovery through cyanidation. This hydrometallurgical process produces a by-product credit of commercial grade antimony trioxide as Senarmontite that can significantly offset the cost of the pre-treatment.

Jan 1, 2007

By J. Swanepoel, J. H. van Laar, J. C. Vosloo, W. A. Pelser

Deep-level underground mining costs in South Africa are continuously rising due to the increased depth at which gold is being mined, resulting in a rise in virgin rock temperature and an increase in cooling requirements. Therefore, mines must evaluate various ventilation and cooling optimisation projects required to be implemented throughout their life of mine (LOM). This study develops a method to identify and prioritise large capital expenditure (CAPEX) underground environmental improvement projects, to improve thermal comfort underground. The solution presents a ‘multi-criteria decision-making’ (MCDM) process, incorporating the ‘analytic hierarchy process’ (AHP) and the ‘technique for order performance by similarity to ideal solution’ (TOPSIS) into the method to provide for scientific decision-making. These projects are evaluated based on four criteria, namely project risk, the impact on the underground thermal comfort, cost, and implementation time. This study’s solution uses ventilation simulations to determine the impact of the projects on the underground environment. The identification and evaluation of an environmental improvement project to best suit the current economic climate, while improving underground conditions and decreasing the safety risk is an essential aspect of the solution developed in this study. The method was implemented on a mechanised deep-level underground mine and showed that surface refrigeration is the most suitable alternative, which was implemented at the case study mine as validation of the developed solution. The study proves that the MCDM method is an adequate solution to incorporate subjective criteria into the decision-making process, resulting in a scientific and structured approach to making significant and complex decisions.

Feb 17, 2023

By Richard Collins

The projected depletion and the increasing costs of petroleum and natural gas along with the public and governmental resistance to nuclear energy have caused coal to emerge as one of today's answers to both our short term and long term energy needs in power generation. In order to satisfy this need, major increases in coal production are mandatory, thus requiring more and higher capacity coal transfer terminals. The logic for selecting coal as the major fuel for power generation is based on many different reports on the existing and potential energy sources, which include petroleum, natural gas, hydropower, solar, geothermal, and nuclear. The following is a brief synopsis of these reports for each type of energy.

Jan 1, 1978

By Jodi Banta

In an effort to reverse the trend of declining enrollments to mining engineering programs that began in 2015, the University of Arizona has implemented a number of interventions over the past five years, including ramping up its pre-college mining education and outreach, and undertaking several enrollment research projects. This article is the second of two installments to discuss the results of our latest study. The first part can be found in the September 2025 issue of Mining Engineering magazine. To better understand mining’s competitive position, the School of Mining Engineering and Mineral Resources conducted a comprehensive study to determine: 1. How prospective college students, parents and educators perceive the industry, related careers and the mining engineering degree. 2. Factors affecting students’ choices of degrees and career plans. 3. The roles parents and educators play and how they influence students.

Nov 1, 2025

By F. L. Bazzanella

Cyprus Pima has two concentrators, one with a conventional crushing-grinding circuit and the other using semi-autogenous grinding followed by ball mills.

Jan 1, 1978

By Zhonglin Ye, Guangping Dai, Ba Zhang, Yonggang Wei, Shiwei Zhou, Bo Li, Hua Wang

Decreasing copper content in slag is critical for improving copper recovery, where apparent viscosity is the main factor affecting the separation of matte/copper from the slag. The viscous behavior of copper converter slag was investigated during reduction process in this paper, and its non-Newtonian viscous behavior and shear thickening characteristics were clarified. The effects of silicate structure and solid particles in the melt on the slag apparent viscosity were investigated. As slag cleaning proceeded in an electric furnace, the magnetite gradually transformed into ferrous oxide, increasing the FeO/SiO2 ratio. With this ratio increased from 1.2 to 2.0, the slag structure was simplified, and its apparent viscosity decreased from 0.26 to 0.12 Pa·s at 1523 K. The iron phase was excessively reduced to metallic state; the slag contained metallic copper-iron alloy particles, increasing apparent viscosity. The apparent viscosity and phase structure of the slag corresponding to the iron phase reduction process were analyzed in detail; the results obtained in the present study are of great significance to the reasonable control of the converter copper slag cleaning process.

Nov 7, 2022

By Chaoxun Zhao, TAIYOU LI, JIAQI JIN, Chen-Luh Lin, Jan D. Miller

A large portion of the energy consumed in copper concentrators is used to reduce the particle size of the feed by crushing and grinding. The cost of metal production could be reduced if low-grade particles of centimeter size were removed prior to further processing. Two copper sulfide ore samples (3 × 1 cm) from Arizona were analyzed by micro X-ray computed tomography (Micro-XCT) to determine the grade of copper sulfide in each particle. For copper ore sample A, a significant number of particles contained very low amounts of copper, while some particles had copper sulfide grains of millimeter size. Based on Micro-XCT, it was expected that 85 percent of copper for sample A could be recovered at 65 percent of mass rejection during preconcentration by sorting. However, in sample B (a different copper ore), distribution of copper sulfide was dispersed primarily in each ore particle, so for the particle size class of 3 × 1 cm, liberation of copper sulfide and gangue minerals was not significant. In view of the XCT results, dual-energy X-ray radiography was used as a basis for sorting. Pilot-scale X-ray sorting of sample A (10 × 1 cm) showed 31 percent rejection of a 0.08 percent Cu gangue product with a corresponding recovery of 90 percent copper.

By P. Gelfi, J. Vanderbeek, J. Enriquez

"The Cerro Verde copper-molybdenum mining complex is located near Arequipa, Peru. A 108,000 t/d copper concentrator (C1 concentrator) commenced operation in late 2006 and was debottlenecked to a 120,000 t/d capacity in 2011. A feasibility study, initiated in May 2010, assessed the potential for expanding the processing rate of the large Cerro Verde sulfide reserve via the installation of a second, stand-alone, concentrator (C2 concentrator) capable of processing a nominal 240,000 t/d ore. The feasibility study was successful and the project advanced through engineering, permitting and construction. Ramp up to nameplate capacity was ahead of schedule. The overall project was completed on schedule and within budget. The details of the project and supporting components are described. The design philosophy and design basis of the concentrator facilities are discussed as are factors that influenced the concentrator layout. Risk mitigation features included in the design are reviewed. The factors that drove the successful and rapid ramp up to nameplate capacity are discussed. Operational experiences in the first year of plant operation and project lessons learned are described. INTRODUCTION/BACKGROUND Sociedad Minera Cerro Verde S.A.A. (SMCV) operates a copper mine near Arequipa in southern Peru. Small scale operations operated intermittently until 1970 when the deposit reverted to the ownership of Minero Perú S.A (Peruvian government). Minero Perú S.A. commenced mining and processing of oxide reserves in 1972 and placed an SX-EW plant into production in 1976. The ownership of the property has changed hands several times over the years. Minero Perú sold Cerro Verde to Cyprus Climax Metals in 1994. Cyprus was acquired by Phelps Dodge in 1999. Freeport-McMoRan (FCX) acquired Phelps Dodge in 2007. Several studies were undertaken during the 1990’s that tried to establish the economic justification to process the large primary sulfide resource that underlies the surface oxide deposit. None of these studies produced an economic conclusion until a feasibility study was completed by Phelps Dodge and SMCV in 2004. This study provided the economic justification for the construction of a 108,000 t/d concentrator during 2005 and 2006. The key to the success of this study was identifying a water source that was sufficient to support processing economies of scale. Concentrator operations commenced in late 2006. The original design production rate of 108,000 t/d was achieved on a 30 day moving average basis on the 266th day after ore was first introduced. During 2009, studies and evaluations were performed that had the objective of addressing observed concentrator bottlenecks to allow a production rate of 120,000 t/d to be achieved. The 120,000 t/d figure represents the sustainable production limits associated with the installed primary crusher and tailing thickeners which would have been prohibitively expensive to upgrade. Debottlenecking activities were implemented during 2010 allowing sustained production rates of 120,000 t/d to be achieved."

Jan 1, 2017

By John A. Reeves

The unit-train concept of moving raw materials .is considered by many railroad men as the most signifigant contribution to reducing rail freight costs since the introduction of the diesel locomotive. The idea, which involves assigning railroad equipment to only one haul and keeping the equipment rolling results in the maximum utilization of equipment. For example before the unit train was plaged in servige on coal hauled to one of Mid. Continent's customers, about 900 cars and 9 locomotives were needed to move the coal requirements for this plant, compared with. 250 cars and 6 locomotives used by the present scheduling of unit trains. If the economics of unit-train movements are to be achieved, coal companies no longer can use railroad cars as small storage bins on wheels to accumulate their coal in trainload shipments, but, rather, must build large bins which incorporate facilities for the rapid loading of railroad cars in a minimum length of time. In this manner railroad equipment is operated at a high degree of efficiency 'with consequent dollar savings. After negotiations between Mid-Continent, the customers and the Railroad, it was decided a unit train loadout and storage facility at Carbondale was required in order to reduce the delivered price of coal to the customers and thereby contribute to the reduction in the cost of manufacturing steel. Carbondale was selected as the bin site location, because the cost of constructing a railroad to Redstone could not be justified for the tonnages anticipated.

Jan 1, 1969

By N. Damiano, C. Zhou, R. Jacksha, J. Srednicki

Modern electronic devices and systems used to enhance miner safety and health are becoming commonplace in underground coal mines. The ability for these devices and systems to function properly in the presence of electromagnetic emissions from other electronic and electrical devices and systems is not entirely understood. To investigate potential electromagnetic compatibility issues of critical mine electronic devices and systems, researchers from the National Institute for Occupational Safety and Health (NIOSH) are conducting surveys of electromagnetic emissions in underground coal mines. This paper presents the measurement system, methods, and results of electric field electromagnetic emission surveys conducted in three underground coal mine environments in the frequency range of 10 kHz to 1000 MHz. The survey data show that in some environments electric field electromagnetic emissions in underground coal mines approached or slightly exceeded limits as defined by other industrial sectors.

Mar 2, 2022

By Barbara Maren Winkler

For mine production problems in mines with varying qualities, both open pit and underground, the linear programming method (LP) has been used successfully. By this method it is possible to keep the total production blend for each period within a required range of qualities while optimizing objectives like production costs, net return, ore grades, other qualities, or a combination of these. Technical restrictions like constrained capacities can be added to the model. This makes LP a flexible and powerful tool for mine production planning. Practical experiences have shown the major influence fix costs have on the actual economic result of a planning decision. It can be proven that fix costs cannot be included in LP models. We describe a way to address this fix cost problem by using mixed integer linear programming (MILP) as an extension to LP in the optimization of a mine planning problem. This raises the issue of complexity. We discuss the computational complexity of the resulting models and the enhancement of model flexibility for the user of a planning system. We demonstrate the method embedded in a practicable everyday planning system for a complex underground coal mine. By computational examples we show how the method improves the economical results of the planning.

Jan 1, 1996

By D. Brady

When deciding to deploy rescue teams underground the decision makers need to be able to determine that there won?t be an explosion whilst the rescue teams are underground. Previously general body concentrations in areas likely to be travelled were compared to explosive limits on a one off basis with no formal process looking at trends or other areas. A new approach is being adopted that takes into account the rate of change of gas concentrations with triggers set to enable a withdrawal of personnel prior to a possible explosion and influences such a barometric pressure changes. This paper explains the rationale behind the changes made and the advantages and implications of adopting such an approach.

Jan 1, 2012

By Harold J. Schock

The cases of no auxiliary ventilation and ventilation with tubing were mathematically modeled, using a turbulent dispersion model. The scooptram that is used to load is modeled as a variable-speed, variable-strength source of pollutants moving in and out of the dead-ended drift. Model predictions are compared to experimental measurements. A parametric analysis was performed to determine the effect of exhaust pipe location and time spent out of the drift, as well as to determine if a relationship existed between CO2 and NO levels. It was concluded from this analysis that when modeling a load-haul-dump cycle, it is necessary to use a model that has the capability of predicting changes in source strength as well as source location. It was also determined that four relevant factors include effective heading height, apparent longitudinal diffusion coefficient, transverse concentration gradient at the face, and average dispersion width of the exhaust jet. As these factors change with heading geometry and ventilation configuration, they were determined experimentally, Carbon dioxide was used as a tracer to calibrate the model; since, knowing the fuel flow rate, it is possible to calculate CO2 production. The above four factors in the computer model were calculated using a regression analysis, comparing predicted local concentrations to measured local concentrations. The model was then verified after this calibration process using additional experimental results. With the calibrated model, it is possible to predict pollutant concentrations at any location in the heading using an engine map and the previously calculated flow field. A parametric analysis shows that the exhaust pipe location can have a significant impact on operator exposure to exhaust gases. It was also shown that NO concentration varies directly with C02 levels. Predictions using the dynamic model are contrasted with constant source strength (pollutant flow rate) results. An analysis of these predictions for computing time-weighted average NO shows the dynamic model predictions of operator exposure to this pollutant to be less than one-half of the value predicted using a constant source model.

Jan 1, 1981

By Michael Stanwood

Project feasibility no longer involves just technical and economic viability-today's feasibility study must include environmental, regulatory, and political considerations as well. While the US now appears at least somewhat committed to developing synthetic fuels, including oil shale, it is the environmental issues, rules, regulations, and guidelines that will play the major role in determining the timing, magnitude, and overall scope of synfuel development in the coming years. The key environmental obstacle affecting oil shale development is uncertainty. Although oil shale may be the most environmentally studied "new" technology in the world, little is known with much degree of certainty about potential environmental consequences of one full-scale commercial facility, or the effects of a massive development effort in a relatively pristine and sparsely populated area. Other primary environmental uncertainties include: • Environmental compliance costs and their effects on investment decisions; • The reliability and acceptability of anticipated pollution control technologies; and • The confusing, time-consuming environmental regulatory framework, which requires more than 100 permits, clearances, and reviews before development occurs. This discussion will focus on the latter uncertainty, and will describe he current status of potential constraints to oil shale industry development in five areas: water availability; water quality degradation; air quality degradation; reclamation and spent shale disposal; and community impacts.

Jan 1, 1981

By C. Meyer, J. J. Eidel

C. W. Hunt I wish to register strong disagreement with the choices of drilling sites chosen by the Continental Scientific Drilling Committee, while endorsing the stated objectives. Of special significance is the lack of any site involving the metals most needed today in the US, while 9 to 13 km of drilling are allocated to gold and silver districts and 11 to 17 km to base metal (mainly copper) districts. Why is nothing proposed for platinum group or chromite? Is this because the committee did not know of such a site? If so, I offer such a site in California (see Fig. 1). The mineralization shown in Table 1 occurs in a large peridotite body in western Tehama County, CA. Petrography has demonstrated unequivocal evidence of migrated PGE deposited in peridotite and chromite of hypabyssal nature. Active diapirism (due probably to serpentine buoyancy) above a reactivated mantle to surface conduit marks the position of the conduit. Young explosion breccia cemented loosely by volcanic glass and tuff demonstrates the significance of the conduit as the prime source of the various emissions. Deep drilling could result in major metals discoveries as well as shedding light on the grand questions of platinum group mineralization. What role water has played in this occurrence is not yet certain; but chlorine and asphaltite have been detected in and adjacent to native PGM, suggesting a major role for water. The explosion breccia suggests that this excellent site could overlie entrapped geothermal steam.

Jan 6, 1987

By Thomas M. Larimer

Prior to April, 1961, the coal charge to Clairtonts coke oven batteries was 3" x 0" mine waslied coal having approximately 6.0% to 7.0% moisture. Even at this size and moisture content, the arching, rat-holing and hang-up was excessive and the effective live storage of coal was only 60% to 70% of the rated capacity of the coal bunkers, depending upon the moisture of the coal. In addition, many production delays were encountered in the time and methods required to fill the larry cars. The need for an improved metallurgical coke led to the introduction of pulverized coal to a portion of the plant in 196 1. When the full potential of the pulverizing equipment was realized, we were able to serve seven batteries in our second unit of batteries with pulverized coal through two coal bunkers. The discharge hoppers of these bunkers were equipped with air vibrators to assist the flow of pulverized coal into the larry cars. The vibrators were helpful in this respect but required considerable maintenance and caused damage to the bin plates.

Jan 1, 1968

By Hugh R. Rhys

The question of the desirability of recovering cullet from MSW in order to recycle it into the manufacturing of glass containers remains a controversial one. The main factors appear to be: 1. The position of the Glass Container Manufacturers Institute (GCMI), as the trade association for most container manufacturers, is that post-consumer cullet is a vital source of raw material. Present requirements are for: a) Flint cullet b) Non-flint cullet of known mix proportions c) Mixed unsorted cullet of known mix propertions c) Mixed or non-flint cullet of unknown mix proportions. A market balance for these products exists, and this might somewhat limit the outlets for (b), (c) and (d), or severely limit the outlet for (d) alone. 2. The color specifications are rather strict. With cullet admixtures of 20% of the melt or more, and the use of decolorisers in a flint furnace discouraged because their action is reducing in a process which requires an oxidising environment, color contamination in a flint furnace is serious.. For amber and green furnaces (reducing) it is less serious, but in order that the quantity of decolorisers may be controlled, the color balance (as a measure of the Fe and Cr content) of the admixtured cullet should be known. 3. Why not simply color analyze, either by a continuous on-stream or off-stream: photo-electronic analysis, or by systematic batch sampling (with some kind off electronic surveillance of the mainstream) and just send mixed, color measured cullet to only amber and green furnaces? The flint would-be simply included in the mix. This is probably technically feasible, but is subject to the market limitations noted in point1.

Jan 1, 1975

By Y. Luo

Highwall mining, which is a relatively new mining method, is a preferred and often the only feasible method for extracting coal reserve left by surface mining operations in areas with steep terrain and in closely spaced thin coal seams. Though its safety record is comparable to that of surface mining, failures of mine structures in highwall mines, especially the highwall, have occurred. Methods for the systematic designing of highwall mines to meet the safety and operational challenges are still evolving. This paper presents the results of research into improving the existing design methods and developing new ones for highwall mining operations. The design methodology is aimed at ensuring structural stability of the highwall, roof, web and barrier pillars and preventing subsidence. It takes into consideration the major ground control challenges of soft and layered mine roofs, and interactions from mining closely spaced coal seams. An optimization design process applying a pressure arch concept can be incorporated to improve the recovery rate of coal reserve. A computer program based on the design methodology was developed.

Jan 1, 2015