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By Dwayne C. Kicker, Duk-Won Park

As the use of longwall mining increases in the U.S.. there is a need to better understand the stress redistribu- tions indicative of this method. To control high stress concentrations, the yield pillar concept has been developed. A physical longwall mine model has been designed to study the effect of yield pillars in deep mining. The model in- cludes sensitive stress measuring devices, a new excavating technique, and a new model material. This study includes the use of both regular and yield pillar systems and has successfully simulated the mode of stress change in chain pillars.

Jan 1, 1986

By Ben H. Daud

A computer model has been developed at Consolidation Coal Co.'s Central Engineering Dept. for preliminary economic evaluation of deep coal mine reserves. Since it was first formulated more than two years ago, the model has been used for the following purposes: (1) ranking studies of coal exploration projects, (2) marketing surveys, (3) preliminary sale and acquisition analysis of coal reserves, and (4) parametric analysis in conjunction with detailed feasibility studies.

Jan 1, 1979

By John C. Edwards, Robert C. Bates

Modeling uranium mine radiation control methods and natural environmental radon variations is an extremely complex endeavor. A number of authors have examined particular facets of the problem and have proposed models for their area of interest. Bureau of Mines personnel brought together many of these individual studies, and from them have attempted to develop a coordinated plan for modeling radon daughter concentrations in the uranium mine environment. This approach is described.

Jan 1, 1981

By S. Formby, J. Avraamides

Transportation of sodium cyanide from factory to minesite often attracts adverse comment from both the community and government agencies. In Western Australia the transportation of 30% w/w aqueous sodium cyanide solution raised fears in the community concerning the safety of such material in the event of spillage. The Chemistry Centre of Western Australia initiated a study of the effects of such a spill, to determine appropriate short and long term response strategies. Factors which were considered included the rate of hydrogen cyanide gas release under various climatic and soil conditions and the effect of alternative treatments in reducing such emissions. The data collected have been used to plan emergency response procedures.

Jan 1, 1989

By T. V. Vasudevan, J. Blaakmeer

Adsorption experiments were conducted at two different solid loadings to investigate the mechanism of oleate adsorption on apatite. Adsorption density at pH 10 was found to be dependent on solids loading in an oleate concentration region where surface precipitation could occur. Analysis of adsorption isotherms indicated three distinct regions of adsorption. In region I (below the region of calcium oleate precipitation), molecular adsorption was observed. Simultaneous molecular adsorption and surface precipitation occurred in region 11, while surface precipitation was predominant in region I11 along with some bulk precipitation. Correlation between flotation of apatite with sodium oleate and the mode of oleate interaction with the surface is established.

Jan 1, 1988

By Gordon E. Ager

A technique for the synthesis of mineral processing flowsheets from laboratory batch test data is described and examples of the application of the procedure are given. The procedure requires the collection of kinetic data, the optimization of the flotation time in each separation stage, then simulation of the material balance for a continuous circuit.

Jan 1, 1989

By M. J. Scoble

There is no straightforward and systematic method for adequately measuring blast damage in on-going mining operations. This paper considers various techniques available for the measurement of blast damage, making particular reference to recent underground hardrock mine studies. This paper concludes by indicating the importance of understanding and accounting for geology and emphasizes the need for a robust damage-audit procedure.

Jan 1, 1997

By Thomas E. Shufflebarger

Glass sand is a virtually pure, fine- to medium-grained, quartz sand. It is produced in 25 states from a variety of chemically different source rocks. Deriving their raw material largely from either friable sandstones or loosely consolidated sands, 59 operations produced 14.9 million tons of melting sand in 1976. About one-third of this tonnage was obtained from the Oriskany and St. Peter Sandstones. Glass-sand prospects are discussed in this paper with regard to chemistry, environment, transportation, and costs. Demand for a quality product will range from 36 million to 46 million short tons in 1995.

Jan 1, 1978

By Hill McDonald

Sand and gravel deposits may be explored by many different methods. The methods used by The Standard Slag Company are primarily two in nature. One is using an auger which is limited in depth by various soil conditions. The other is a heavy wall dry sampler and a heavy wall wet sampler. The heavy wall dry sampler takes continuous uncontaminated samples up to seven inches in diameter. The heavy wall wet sampler takes continuous uncontaminated samples up to six inches in diameter. For us, the maximum depth of the heavy wall samplers has been two hundred fifty feet of which one hundred feet was above the water table and one hundred fifty feet was below the water table.

Jan 1, 1972

By D. Doepker

The dissolution of metals from various metal/ non-metal mine tailings has been studied through column leach tests at US Bureau of Mines laboratories. Metal mobilization in unsaturated columns was consistently greater than metal dissolution in water-saturated columns. Leachate pH was also frequently lower when a leachant was passed through columns but showed a mixed residence-time dependence. On the other hand, metal and sulfate ion concentrations in the leachate increased with dry-cycle residence time. Results suggest that acid formation through atmospheric oxidation of pyrite may compete with non-acid-forming oxidation of other metal sulfides. The two processes lead to decreased pH and increased metal mobilization, respectively. Leach tests using sodium lauryl sulfate indicated that microbial activity was not a factor in these studies.

Jan 1, 1991

By B. Yarar, R. Buchan

Mineral-processing techniques were adopted for use in the separation of various plastics used in beverage bottles. A complete flowsheet, which utilized size reduction, heavy-media separation and flotation, was developed to separate PE, PVC and PET. In addition, the mixtures contained cellulose fibers (from labels) and aluminum (from bottle caps). It was demonstrated that, while heavy-media separation allows for the separation of a PVC/ PET mixture, froth flotation can be used to separate PVC and PET. For this purpose, the differential action of a pH 11 alkaline aqueous solution containing methanol and MIBC as surface-tension control agents, has been found to be a suitable flotation medium. This paper reports on some aspects of a flotation flowsheet that was developed for the separation of plastics contained in municipal solid wastes.

Jan 1, 1997

By R. J. Lambert

The purpose of this paper is to discuss the application of mine design to the North DeLamar pit of NERCO's DeLamar Mine. Many discussions on mine planning and design focus on computerized mine modeling but neglect the final step of operating design development. Mine planning and design criteria used for the final layback in the North DeLamar pit are included along with a comparison of designed and as-built tonnages, grades and topography.

Jan 1, 1993

By Claude Bazin, Robert Grant, Mike Cooper

An analysis of the Pb recovery as a function of particle size was carried out for the CuPb rougher bank of a complex sulphide mineral processing plant. Results indicate that higher recovery may be achieved by optimizing the flotation feed size distribution. Simulation of the actual grinding circuit has provided guidelines to modify circuit operating conditions in order to improve product size distribution. Plant tests ar

Jan 1, 1991

By S. G. Malghan, V. K. Pujari

Detailed characterization of all the powder constituents during powder processing is necessary for the reproducible manufacture of ceramic components that will perform reliably in intended applications. In this paper, selected physical and surface chemical techniques for characterization of silicon nitride powder are evaluated. The characterization data are discussed in the context of how these data, through their influence on powder processing unit operations, can affect the final microstructure. In the forming of ceramics, some of the major variables of injection molding are evaluated. Accurate measurement and control of these variables is emphasized for manufacture of Si3N4 ceramics with a high degree of reliability.

Jan 1, 1990

Projections of coal reserves in Central Appalachia are essential for long-term planning in the region. Annual production is declining in states such as Virginia. And minable reserves for the Central Appalachian coalfield are challenged by difficult geological, mining and market conditions. To project coal mining longevity in this region, interviews with mining companies were conducted to determine and assess technical and economic factors that affect coal seam minability. This information was ap- plied to seam and coal reserve data developed by state and federal governments. The results were analyzed to determine the effects of various factors on the overall minable coal reserve base.

Jan 1, 1998

By Waclaw Dziurzynski, Janusz Tracz, Danny Wooton, Andrzej M. Wala

The purpose of this paper is to present validation studies of the mine-fire simulator using data gathered from an actual mine fire which occurred in November 1991 at the Pattiki Mine. This study evaluates the suitability of the computer software package for modeling underground fires. The paper also discusses the importance of the on-line monitoring system for the validation process.

Jan 1, 1995

By Marcelino Cortina

It is known that underground bituminous coal mining in the Central Asturian Coal Basin (North of Spain) is a complicated task, due basically to the difficult geological conditions: thin and steep Seams with many faults and other disturbances. Therefore, it is not easy to decide what is the most suitable mining method for each of the seams, and problems in making the correct decision are encountered frequently. Because selections in the past have been inadequate an Expert System, ASTURLABOR;hulla, has been designed and will be developed' to provide accurate advice in the mining method selection process. The paper describes the major features of this Expert System and outlines the ASTURLABOR general project, which includes five other mining Expert Systems to complement ASTURLABOR-hulla.

Jan 1, 1989

By Ronald J. Allain

Water soluble polymers play an important role in many industries. The mining industry is dependent on these materials to help accomplish many solid-liquid (water) separations. Mechanical devices alone are not capable of achieving the degree of separation needed. Mechanical and chemical separations act in concert to accomplish the necessary separation. The history of the use of water soluble polymers has gone through several evolutionary phases and I believe we are facing another of these phases. At first, various natural products were common - starches, gums, and various polysaccharides. These were replaced by the synthetic polymers based on copolymerization of various vinylmonomers mainly in conjunction with acrylamide. The use of these polymers and their needs continues to grow. This paper will cover a brief overview followed by a look at the future of water soluble polymers. A focus will be on applications of water soluble polymers in the mining industry.

Jan 1, 1994

By James L. Parks

This paper describes improvements in SAG and AG mill liner designs and their cumulative effect on wear life and mill availability. Routine procedures used by many SAG and AG mill operators to improve liner life are reviewed. Guidelines are provided for estimating the time required to replace worn liners along with practical methods to reduce downtime for liner replacement. Finally, the effects of mill operating conditions on liner wear life and breakage are considered.

Jan 1, 1998

By José Salim, T. V. Subrahmanyan

The occurence of primary stratiform and vein gold deposits in the Precambrian rocks of Northeastern Brazil is discussed. The stratiform deposits are related to clastic sediments (quartzites and conglomerates). The veins are associated with quartz and sulfides and are structurally controlled by shear zones. The gold was recovered for a long time by small miners. Developmental programmes for large scale mining are now envisaged. The recovery problems and gold economics are also discussed.

Jan 1, 1988