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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 Pat Gochnour, Jim V. Rouse

Advances in the design and construction of heap­leach pads and process plants have greatly reduced. the potential for accidental releases of process olut1on. While workers in the field, and regulatory agencies such as the EPA have long recognized that the potential effects of any spills would be short term in nature due to cyanide attenuation and degradation (Engineering-Science, September, 1986, Pyrih, 1990, Rouse and Pyrih, 198, Rouse and Pyrih, 1991 ), unfortunately the general pubhc has held a perception that such a spill would be an environmental catastrophe. Few factual data on actual accidental releases have been available to dispel such a concept. Such data now exist and shoul? be disseminated to show that prompt response, using a combination of chemical oxidation, natural attenuation, and enhanced biodegradation of cyanide, can limit the effects of such rare releases, in both time and space.

Jan 1, 1992

By Deepak Malhotra, Sean Armstrong, Linda Baltich

The economic profitability of any mineral company is dependent upon maximizing mineral recoveries while minimizing costs. The effectiveness of any strategy to meet this objective is dependent upon firstly obtaining quantitative information concerning the steady-state metallurgical balance of the plant, and secondly, how efficiently this information is used to improve/optimize plant performance. This two-step approach can be designated as a "plant audit." Plant audits on a routine basis can be very expensive and time-consuming. Most plants have reduced staffs to cut costs. The remaining staff has to spend time to solve production/operation problems, thereby leaving limited resources (i.e., people, time, and money), for plant auditing. This paper briefly reviews plant auditing categories, and a systematic approach to auditing which has been successfully used at several operations. An example illustrating the use of this approach in gold operations is discussed in this paper.

Jan 1, 1992

By James Y. Oldshue, Paul M. Kubera

Most coillillercial processing applications employing mixers in various types of slurry systems are continuous flow. These applications may also be multiple stage, with the stage number varying anywhere from two or three to ten or more. Two questions that usually come up at the beginning of any proposed pilot plant study are (1) can the pilot plant unit be operated batch-wise, and the results extrapolated both on the basis of scale and fluid motion to the full-scale tank which will be continuous-flow (and probably multi-stage), or (2) does the pilot plant need to be operated in a continuous-flow fashion, and if so, does the exact number of tanks/stages that are proposed for the plant need to be used in the pilot plant? We will consider these possibilities in sequence and present the principles involved in running some of the various pilot-plant arrangements.

Jan 1, 1992

By Matthew J. Hrebar

A comparison of hydraulic shovels (HS) versus front-end loaders (FEL) is commonly made when an excavator with some degree of mobility and medium reach is required. These applications are often found in hard rock open pit and surface coal mining applications, among others. The purpose of this paper is to present a comparative economic study of the two excavators. Production data was collected from both HS and FEL manufacturers as well as operating mines. Availability, operating costs, and estimated operating life were gathered from operating mines, while capital costs were obtained from manufacturers. The data was limited to studies and operations which included both types of mid-size excavators. The economic study is followed by a discussion of other factors considered by mine operators in excavator selection. The study was originally made for a presentation at the 23rd Intermountain Minerals Conference at Vail, CO.

Jan 1, 1992

By Eugene R. Palowitch

From the late 1880s to the present, the Appalachian region continues to be a dominant supplier of premium-quality coals. The region contains an estimated 93.4 Gt (102.7 billion st) of demonstrated reserves in Alabama, eastern Kentucky, Maryland, Ohio, Pennsylvania, Tennessee, Virginia and West Virginia. Therefore, Appalachia will remain a source of quality coals for the metallurgical, export and utility markets. Figure 1 shows the annual production of coal in Appalachia and nationally from 1970 through 1993 (Energy Information Administration, 1994). During that 23-year period, annual domestic coal production almost doubled. Coal production from Appalachia increased at an average annual rate of only 0.7%. Coal production remained essentially constant at about 409 Mt/a (450 million stpy). Thus, Appalachia's market share decreased from 69.8% in 1970 to 47.2% in 1993 - a drop of almost one-third (Energy Information Administration, 1994).

Jan 1, 1995

By A. N. Papadopoulos

The life cycle assessment and the performance of pine fence posts treated with water borne preservatives and oils after 18 years exposure in ground contact were examined in this study. Vacuum CCB treated fence posts were subsequently treated at their lowest part (ground contact) with creosote using the open hot and cold tank process and exposed under warm dry temperate climatic conditions in Greece. After 18 years exposure, samples were taken from the above ground contact, top, middle and ground contact and tested for toughness using a Denison single blow impact bending test machine. There was no significant reduction of toughness in any of these zones. Chemical analysis of the residual CCB of unexposed and exposed samples by ICP showed that copper and chromium losses were insignificant while boron losses were significant (more than 50% of the initial content). This was attributed to an effect of creosote treatment.

Jan 1, 2008

By G. Capello

Carboniferous mining basins are today a non-negligible source of energy. So important in fact that returns now justify high investments and costs even for those deposits that were un-economical in the past. Nowadays, if properly explored and exploited, basins previously considered non-minable due to complex structural and stratigraphical situations may be economically interesting. It is while studying a faulted basin with such features that the Authors developed the described computer-aided methodology capable of constructing a model of the physical structure of coal deposits on the basis of stratigraphical data from drillings. The aim of the procedure is to define coal reserves, the exploitation of a deposit being conditioned by the possibility of identifying zones that are technically minable. This objective is pursued by making as detailed a reconstruction as possible of the geometrical, stratigraphical and tectonic features of the coal-bearing seams of a deposit.

Jan 1, 1982

By Otis M. Clarke

The 34th Forum on the Geology of Industrial Minerals gave members a chance to see the geology of various stone and ore deposits displayed graphically in quarry walls and also provided an opportunity to hear and see first-rate papers and posters on the geology of industrial minerals. Also, some field trips passed through areas of spectacular scenery. As a bonus, participants saw scenic mines, some of which are "pretty as a picture." Watercolor paintings prove it. At the Oklahoma Forum, the writer displayed a number of paintings of mines and other landscapes seen during previous Forum trips. These paintings and this brief article are part of a crusade to prove that some mines and geologic vistas are scenic wonders and belong in our visual heritage. It is a plea to save some of our best geologic exposures for future geologists, tourists, and artists.

Jan 1, 1999

By F. Figge, T. Hahn

In this article we present Sustainable Value, a valuation methodology to assess sustainable value creation of companies. Sustainable Development posits that decisions must not only take into account economic capital but also natural and social capital. Sustainable Value, the methodology presented in this paper, borrows the idea from financial economics that the return on capital has to cover the cost of the capital. Capital costs are determined as opportunity costs, i.e. the forgone return that would have been created by an alternative investment. By expanding the well established logic of the valuation of economic capital in financial markets to also cover natural and social capital we provide a methodology that allows an assessment of the most efficient allocation of economic, natural, and social capital for sustainable value creation in companies. We demonstrate the practicability of the methodology by the valuation of the sustainability performance of British Petroleum (BP).

Jan 1, 2005

By B. Das, B. K. Mohapatra, K. S. Narasimhan, S. K. Bhaumik

The iron ore slimes (d80 ~ 50 µm) generated at Noamundi iron ore washing plant (TISCO), assaying 57% Fe, 4% Si02 and 8.3% A1203, have been subjected to hydrocyclone studies. The effects of different design and operating parameters have been studied to get a product suitable for subsequent use in the sinter mix. The studies indicate that it is possible to obtain a product containing 64% Fe, 1.4% Si02 and 3.5% A1203 with a recovery of 49% iron. The process involves classification followed by separation in a hydrocyclone. By this method, the overall yield of iron ore production in the plant is expected to increase by 8%. Microscopic examinations and X-ray diffraction studies were conducted to elucidate the mineralogy and liberation characteristics of Noamundi iron ore slimes. This paper deals with the findings of the investigations.

Jan 1, 1993

By V. Saltas

The present work investigates whether dielectric spectroscopy can be used to detect contamination, which may appear in a natural porous material, due to the spreading of pollution. For this purpose, dielectric and conductivity measurements, in the frequency range of 10mHz to 1MHz, were carried out in sandstone samples, partially filled or saturated with solutions of leachates, at different concentrations. The experimental results suggest that although the role of water is dominant to the measured electrical conductivity, variations of two orders of magnitude are observed due to the different concentrations of leachates, in partially filled sandstone samples. Experimental data are well fitted with a Havriliak?Negami dielectric relaxation function, superimposed with a conductivity term. The parameters of the fitting function have been correlated to the concentration of leachate in the sandstone samples and considerable changes have been observed at low leachate?s concentration.

Jan 1, 2005

By V. Avdiyskiy

The most pressing topic raised nowadays by the world community faces environment and social consequences of the business intensification process, primarily that of mining and mineral industry, which is through the number of its activities mostly associated with pernicious impacts. World top managers are confronted with the dilemma of reconciling traditional financial framework aiming at successful business development measured by revenues, shareholder value, profit margin and incorporating Sustainable Development (SD) at all levels of decision making process, avoiding depriving future generations of the means to meet their own needs. The rapid consolidation and globalization of the industry stipulates that companies are an integral part of the world economic environment. Therefore a company?s financial performance is under the pressure of operational and environmental performance. Among them special attention is paid to the social and economic background, the relationship with regulatory institutions, and the developments for environmental protection.

Jan 1, 2003

By C. A. Wiggins, J. M. Kennedy

The Benbrook Connection tunnel forms approximately 6,666 m (19,560 ft) of17,678 m (58,000 ft) of raw water pipeline connecting Lake Benbrook with the Rolling Hills Water Treatment Plant. This connection is designed to minimize costs to the owners, the Tarrant Regional Water District, for providing raw water to its’ various clients. The geological formations through which the tunnel passes and the design requirements resulted in some-what unique applications of initial ground support systems which were modified by the con-tractor to optimize the mining operations. The pipe sections, fabricated in 12 m (40 ft) sections, are concrete lined and coated steel pipe. Construction of the work shaft and tail tunnel was also modified to suit the contractors methods. A Lovat universal TBM was chosen to excavate through the various rock types. The pipe sections will be transported using beam carriers.

Jan 1, 1997

By Chris Mark

In the wake of the Crandall Canyon mine disaster, the U.S. Congress asked the National Institute for Occupational Health and Safety (NIOSH) to study the safety of deep cover pillar recovery operations in the US. The legislation defined ?deep cover? to be greater than 1,500 ft, but NIOSH is also evaluating mines at depths greater than 1,000 ft when multiple seam interactions are encountered. By these definitions, there about 35 active mines that engage in deep cover pillar recovery, in the states of UT, CO, VA, WV, and KY. To date, NIOSH has documented ground conditions and ground control experience at nearly all of them. This paper provides an overview of current deep cover pillar recovery practice. Specific ground control issues that are discussed include: Pillar and barrier pillar design, ? Coal bumps, Thick seam pillar extraction, and ? Multiple seam interactions.? INTRODUCTI

Jan 1, 2009

By Terry Mudder

Long-term anaerobic biochemical treatment for draindown of residual solutions is a cost-effective way to close a heap-leach pad. This article presents a laboratory evaluation of anaerobic biochemical treatment of cyanide heap-leach pad solutions. The traditional approach to heap-leach pad closure is to rinse the pads with multiple pore volumes of fresh or recycled treated water. The effluent from an initial rinse is often treated and recirculated until the solutions passed through the heap meet the appropriate numeric and narrative water quality standards. Column rinsing tests are completed during project planning to determine the number of pore volumes of fresh or recycled treated water required to rinse the pad to meet long-term closure requirements. A traditional closure plan generally includes provisions to sample the rinse effluent and rinsed solids (the Meteoric Water Mobility, Procedure or USEPA 1312) to verify that chemical requirements are being met.

Jan 1, 1995

By E. F. Divers, R. A. Jankowski

In response to a request from the Mine Safety and Health Administration (MSHA), the US Bureau of Mines completed a respirable dust survey of 18 US coal preparation plants. Of these, three were essentially free of dust problems. Respirable dust exposure to workers in the remaining plants depended on the time spent in the dusty areas. In five of the plants surveyed, Bureau tests showed that in some areas worker exposures could exceed Federal dust limits in less than two hours. Cooperative studies were arranged with coal preparation plants using three different dust control techniques. These included a standard baghouse-type dust collector, two types of scrubbers, and an electrostatic precipitator. Results of these evaluations are presented. Various types of ventilation systems used during summer and winter conditions were also evaluated. Results showed that appropriate ventilation can provide a highly cost-effective method for controlling coal preparation plant dust.

Jan 1, 1987

By Robert Rautenberg, Ted Budd

The paper will discuss the successful construction of the largest dollar value ($194.5 million, U.S.) TARP (Tunnel and Reservoir Plan) project built to date for the Metropolitan Water Reclamation District of Greater Chicago. The mining and lining of the 18.5km (11.54 miles) tunnels will be emphasized. The tunnels were driven utilizing three TBMs ranging in size from 9.85m (32.33 ft) to 3.70m (12.16 ft) in diameter. The operations surrounding the 11,546m (37,876 ft) long 9.85m (32.33 ft) diameter tunnel will be highlighted. A total system concept was utilized to attain mining rates up to 29.3m (96 ft) per shift and lining productions of 58.5m (192 ft) per day. The reliability of these systems was instrumental in the completion of the project more than a year ahead of schedule.

Jan 1, 1995

By Markku Virtanen, Pertti Koivistoinen

From the perspective of a large mining company the comminution circuit design is worth keeping within the boundaries of the organisation. The correct circuit design begins from the understanding of the role of grinding. Grinding is a link only in the long "comminution chain," starting from solid rock and ending at the concentrating stage. The final target in comminution is to take a part in the maximization of Net Smelter Return, which goal provides the simultaneous considering of capital costs, operating costs and the economic effect of process results. As a general rule there will be a single crushing stage only, ahead of the grinding process. Grinding does not use any metallic grinding media at all, and there will be fine crushing for critical material in the grinding circuit. Grinding has a minimum two stages, besides, at many concentrators middling products and quite often also tailings are reground.

Jan 1, 1997

By David R. Baughman, John C. Gathje, K. C. Oberg, Gary L. Simmons

Santa Fe Pacific Gold Corp. conducted pressure-oxidation pilot plant studies on refractory carbonaceous gold ores from the Twin Creeks Mine in Nevada. The tests were conducted at Hazen Research Inc., Golden, CO, during 1993 and 1994. Laboratory investigations using CIL cyanidation after batch pressure oxidation demonstrated gold recoveries of 90% to 95%. However, pilot plant testing showed that several of the same ore types responded very poorly, with gold extractions of only 45% to 75%. Plant testing was suspended for approximately four months while extensive research was conducted to determine why these ores responded poorly and to identify potential solutions. This paper describes the batch and pilot plant test results, the extensive research activities that eventually identified the cause of the gold recovery problem and the final semicontinuous and continuous pilot plant operations that confirmed possible solutions. Final pilot plant results showed gold recoveries that were consistently greater than 90%.

Jan 1, 1999