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By J. J. Crowhurst

The modem open pit-heap leach operation by Pegasus Gold Ltd. at Zortman and Landusky in Phillips County, Montana, is a new chapter in the mining of gold in these districts. The discovery of bulk tonnage ore bodies and their development and ultimate production was based on a long history of mining and exploration in that part of Montana. Gold was originally discovered in the Little Rocky Mountains as placer deposits by Pike Landusky and Lou Myers. This discovery in the 1880s was not significant, but Pike Landusky continued prospecting for lode deposits, and he eventually located the Gold Bug and Little Ben, two of the larger Au-Ag producers in the district. Eventually two camps, Landusky and Zortman, grew in the LittleRocky Mountains. By the time Landusky was killed in 1894 by Kid Curry, the district was still a discontinuous small producer. Steady production commenced in 1907 with the organization of the August Gold Mining Co. Eventually high grade ores on specific veins were exhausted by selective underground mining and the district was idle by May 1942. After World War II in the early 1950s. E.A. Scholz tried to continue selective underground mining, but he realized the stockworks surrounding the larger veins constituted bulk tonnage targets. Ultimately in the 1976- 1979 period he organized two exploration efforts, one each for the Landusky and Zortman areas, and brought these into production as the Argo and Pegasus gold mines. By the time of his death, Apr. 8, 1980, both operations were producing gold. Later the two companies were merged as Pegasus Gold Ltd. Upon the death of Scholz, V.F. Hollister continued as the geological consultant, Ed Roper was engaged as general manager, and J. J. Crowhurst was given the responsibility of executive vice president. The discovery of open pittable ores and the application of heap leach technology was important in the development of mining. Both contributed to the low cost operation that continues to this day. The attached article by L.M. Rogers, then chief geologist, and M.S. Enders, his assistant, describes the geology of the deposit. It was presented at the Northwest Mining Association meeting in 1982.

Jan 1, 1990

By Stephen C. Tadolini, Thomas M. Barczak

Western mines have had limited choices for standing support. Wood cribs were often too soft and unstable. The introduction of the Can support in the early 1990’s provided a very effective alternative and remains the dominant form of tailgate support. Water-filled prestressing cells are now used to cap the Can and preload it to provide an active roof load. The Cluster Prop, consisting of three timber wedge props bundled together, provides more capacity than an equivalent sized Can support and improves transport efficiency. However, the Cluster Prop is less stable and does not maintain a consistent load throughout its loading profile. Pumpable roof supports are another alternative support, but they have not been proven in high deformation environments. Alternative supports are also being used in longwall recovery operations. These include the Rocprop and Omni Prop, which are extendable support systems. They also provide active roof loading which can be beneficial in these applications. Specialty supports, such as the Sand Prop and Spider Prop, have also been introduced into western longwall operations. This paper compares the performance characteristics of these various support systems.

Jan 1, 2005

By G. Yang, M. J. McPherson, P. Mousset-Jones, G. Danko, F. Calizaya

In the last 20 years, studies on controlled flow recirculation in various countries have been carried out in both coal and metal mines. These studies have shown that in addition to economic gains, partial flow recirculation can be used to provide mine workings distant from surface access points with the required volumes of air. These studies have also shown that the operation of fans and regulators, used in a recirculation system, will induce transients in gas flow and gas concentration. Various models have been developed to explain the problem. However, most have failed to incorporate important factors such as diffusion and dispersion in the modeling process. This study examines the theoretical background of gas emission transients from caved areas in coal mines, represents the problem by a "tank-airway" network model, and provides a possible solution. The study also presents the results gained from a laboratory model constructed to evaluate the major factors affecting the shape and duration of gas flow and gas concentration transients in an airflow recirculation system. In this model, the gas injection system was rearranged to simulate the variations in gas emission rates due to changes in air pressure. Within this model, a set of booster fans and regulators were used to generate the changes in air pressure within the model. Finally, the study presents an algorithm and a computer program GASTRAN, developed to analyze the gas concentration transients and calculate the pollutant transport levels in a complex ventilation network. The application of the program is illustrated by means of an example problem.

Jan 1, 1991

Machine breakdowns and maintenance delays are large contributors to lost production and increased operating costs in the mining industry. The US Bureau of Mines is investigating the applications of expert system technology to diagnostic and predictive maintenance for mining equipment. This will help increase mining productivity and decrease operating costs by reducing the frequency of equipment failures and repair times. The Bureau has begun this effort by applying expert system techniques to the diagnosis of hydraulic system problems on a continuous mining machine. This paper discusses the development of the hydraulic diagnostic expert system.

Jan 1, 1992

By Y. C. Kim

This paper describes the implementational aspects of a blast hole kriging system that has been developedfor the purpose of daily ore/waste control in an open pit mine. The primary goal of blast hole kriging is to improve the ore/waste delineation procedure. A complete computer program package called Blast Hole Kriging (BHK) System was developed for IBMIPC AT or XT computers, using the Fortran language and supplemented by a few assembly language routines for the bit- map manipulation. This paper emphasizes the practical implementation requirements of the system and discusses system design considerations.

Jan 1, 1991

By G. Wonnacott

A model for simulation of gravity regrinding circuits is presented. The model can predict "secondary" density distribution data from a series of "primary" grind/density distribution tests. Thus middlings regrind requirements can be predicted from primary grind data. Traditional methods of regrind design involve lengthy and tedious tests programmes. The model presented herein can considerably reduce the quantity of testwork required for regrind design. The model can also be used to design primary gravity grinding circuits. A parameter estimation scheme and experimental data validating the model are presented.

Jan 1, 1989

By George J. Bujtor, Anthony K. Scott, Haddon F. King

In 1982, the result of a 3-year study was published as "A Guide to the Understanding of Ore Reserve Estimation". The principal conclusions were that computation formed only part, and perhaps not the most important part, of an estimate and that the estimate should recognize that geological, mining engineering and metallurgical judgements formed an essential part of the eventual result. Subsequent expectation/realization studies of several mines have produced case histories which form the principal basis of the paper. These imply that geology is even a larger factor than thought earlier.

Jan 1, 1992

By Gary Buchan

During several months in 1996 and 1997, Cyprus Twentymile Coal Co. (TCC) set world production records at its Twentymile Mine in northwestern Colorado. These records were due to the company's implementation of a state-of-the-art longwall mining and conveyance system along with a -highly dedicated work force. This article is a case study of the design of long panels at the mine from conception to implementation. Obstacles that needed to be overcome included subsidence engineering, environmental regulations, conveyance, ventilation, equipment design and continuous miner (CM) development timing.

Jan 1, 1998

By T. T. Gronfors

The excavation process and equipment used for excavation join firmly each other. By changing the process or method, the construction of equipment may be altered essentially. It has been possible to develop a wholy new type of hydraulic boom for tunnelling, when only parallel drilling instead of V-cut is used. The utilization of controlled blasting has made small holes more desirable. So the controlled blasting has had an influence on the selection of drill steel equipment and in this way also influenced the construction of the equipment.

Jan 1, 1970

By T. R. von Ow

The method of powering mills such as AG, SAG and Ball has a long and technically interesting history. It can be said that almost every decade in the last half century had its own trend. The trends were dominated by the market demand, the advanced process development and requirement of the mechanical and the electrical technology but mostly by the price of the applied technology. The increasing size of the ring geared mills in the last years requires more awareness on the drive train solution. Special attention must be paid to the mechanics and the requirements of the power grid. Operational challenges such as soft starting and controlled operation as well as the protection of the equipment have gained importance. Frequency converter drive solutions dedicated to single or dual pinion ring-geared mills offer significant advantages over conventional drives due to their application specific features and controls. Solutions with low speed motors as well as high speed motors cover all possible configurations available for ring geared mills.

Jan 1, 2010

By B. Towson, R. F. Dalton, G. W. Seward

This paper reviews the successful application of oxime reagents for the solvent extraction of copper and considers the role that well focussed research initiatives can play in bringing further radical change to the metallurgical industry. Particular reference is made to the Cuprex Metal Extraction Process (CMEP), for the treatment of low grade or difficult to treat sulfide concentrates, using the reagent Acorga CLX- 50 to recover the copper and the reagent Acorga ZNX-50 for the recovery of zinc from chloride solutions. Other new extractants, currently in development, are also referenced.

Jan 1, 1994

Laboratory techniques have been developed at the Julius Kruttschnitt Mineral Research Centre which relate comminution energy to size reduction. These relationships have been applied in the mathematical modelling of autogenous and semi-autogenous mills. Since their development in 1987 these models have been successfully used in many wide ranging design and optimization studies. A description of the basic structure of the models is presented with particular reference to ore characterization. Two case studies are presented which illustrate their effectiveness in evaluating and predicting the effects of circuit changes.

Jan 1, 1992

By A. W. Swanson

Iron carbide, containing 93.3% Fe and 6.7% C, is a tailor made feed for the electric arc furnace (EAF) and has recently gained worldwide attention as a possible replacement for premium quality scrap. With 38% of the steel in the United States being produced in EAFs, iron ore producers have an interest in becoming direct suppliers to the EAF industry. This paper explains the advantages of using iron carbide in an EAF and describes test work on the product and development work being per formed on engineering designs for a commercial plant.

Jan 1, 1994

By Robert P. Mahoney, William J. Roe

Polymers of a wide variety of composition are used in coal and mineral beneficiation. Applications include flocculation and coagulation in thickeners, filtration enhancement, mill scale control, dust control, ore leaching improvement, and pond management. The proper chemistry of the polymer is determined by many factors, including the nature of the process, mineral type, and respective performance requirements. This paper provides an overview of the various current applications of polymers in mineral processing, and a description of the applicable polymer chemistries which find utility in these applications. Examples of structure/performance relationships are discussed.

Jan 1, 1994

By L. B. Rothfeld

Two new coal use technologies are on the verge of commercial acceptance by the utility industry: atmospheric fluidized bed combustion (AFBC) and gasification combined cycle (GCC). Generating plants under construction or in planning will replace older pulverized coal (PC) boilers or substitute for new PC boiler capacity. This paper reports recent developments in the commercialization of AFBC and GCC, emphasizing the potential impact on the coal mining industry. The influence of coal quality characteristics on fuel selection is explored by means of preliminary economic calculations for different coals and competing fuels.

Jan 1, 1987

By T. Seal

The Hydro-Jex technology has been used by Newmont Mining Corp. on the gold heap leach pads on the Carlin Trend - Nevada for three years to recover the inventory gold and change the chemistry in the pads. This research and development patented process is complete with the resultant data presented. Information on drill sampling, geophysical surveying, followed by leach pad stimulation with impacts on solution chemistry and gold recovery are discussed. Can this technology be used to rinse and close heap leach pads faster with reduced pump energy costs and improved recovery?

Jan 1, 2007

By J. F. Able, F. Djahanguiri

The US Bureau of Mines conducted research on underground stope leaching of metalliferous ores. Leaching underground would minimize the environmental impact of ore processing on the surface and would maximize minable reserves. An important aspect of this process is the minimization of pregnant solution losses and groundwater contamination by leach solutions. Bulkhead design and construction are important issues for solution control and stope-leaching economics. A reinforced-concrete bulkhead was designed, constructed and tested for solution control in an underground mine near Idaho Springs, CO. This paper presents the bulkhead-design methodology and construction procedure.

Jan 1, 1998

By Pradip

Chelatang agents, because of their metal specificity, can function as effective mineral processing reagents. A brief review of the work carried out in this area is presented. Some of the salient features of mineral flotation and flocculation with chehting-type reagents, such as bulk us. surface chelation, the role of pH, mineral solubility, solution chemistry of reagents, and temperature, are illustrated with appropriate examples. The problems associated with the commercialization of chelating reagents for ore beneficiation and the research efforts required in this area are also discussed.

Jan 1, 1987

By Joseph A. Zupanick

Methane drainage is a mature technology, now commonly practiced in many highly productive underground coal mines throughout the world. Universally, the practice of pre-draining methane will continue to grow as near-surface coal seams become depleted and mining operations are forced to exploit deeper reserves. These deeper coal reserves inherently have higher gas contents. In addition, increases in productivity and extraction rates have caused higher methane liberations per unit of time. As the cost of providing ventilation air increases, the economic justification for implementing a methane drainage program becomes apparent.

Jan 1, 2005

By Ross W. Smith, Xiapeng Zheng, Merrill P. Allen

The results of flotation of a primary desliming hydrosizer overflow material containing 14.6 wt.% P20, and 3.6 wt.% MgO are presented. The phosphate minerals were collophane and francolite and all minerals appeared to be liberated. The material had not been previously treated with flotation reagents. In the experimentation, various collectors were evaluated for effectiveness. The relative effectiveness of flotation in different flotation devices was determined. Finally a two-stage flotation scheme is proposed using column flotation of dolomite in the first stage and Denver cell flotation in the second.

Jan 1, 2002