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By Bill M. Stewart

The Bureau of Mines conducted laboratory tests to determine the effects on the physical properties of coarse coal waste of adding large amounts of fine coal waste. Maximum laboratory dry density, optimum moisture content, shear strength, and permeability tests were conducted on samples that contained 18 to 60 pct minus No.4 (U.S. Standard sieve size) coal waste. For the nonslaky materials, maximum laboratory densities were highest and permeabilities lowest when the samples contained between 30 and 40 pct minus No.4. Shear strength increased rapidly when the proportion of minus No. 4 was increased from 20 to 40 pct, but then increased only slightly or leveled off when the minus No. 4 was increased to 60 pct. Optimum moisture content and permeability were the physical properties most affected by the addition of fines. Optimum moisture content increased as much as 3 pct, and permeabilities decreased up to three orders of magnitude. Slaky coal waste material had physical property reactions to the addition of fines substantially different from those of nonslaky material.

Jan 1, 1981

By D. D. Dornenburg

The effect of changes of atmospheric pressure on methane emissions from extensive worked-out areas of coal mines in several Midwestern States has lone caused concern to State and Federal mining departments, as well as to the operating companies involved. Common mining and ventilation methods employed in mines in these States have resulted in large sealed and unsealed worked-out areas in which considerable quantities of methane are emitted alone both intake-and return-air courses. The common practice is to watch barometric changes very closely and take special precautionary measurer during periods of low barometric pressure. Although the hazard is recognized, mining officials have different opinions concerning the effect of barometric pressure variations on the emission of mine gases. These opinions are based upon scattered personal observations, as no records exist of actual studies to establish such effects.

Jan 1, 1955

By Michael D. Fenton

Bauxite resources were primarily in Africa, Asia, Oceania, and South America. Only five countries combined, Australia, Brazil, Guinea, India, and Jamaica, contained most of the total world reserves available for extraction under current economic conditions and accounted for nearly 80 % of world production of bauxite. World bauxite and alumina production declined and prices for smelter-grade alumina remained below the $200/mt level during 1993 because of growing aluminum inventories on international markets and declining worldwide demand. The United States imported bauxite primarily from Australia, Brazil, Guinea, and Jamaica. U.S. alumina plant capacity remained essentially unchanged throughout 1993, but apparent capacity utilization decreased by the close of 1993. Chromium Most of the world's known resources and reserves of chromite are located in India, Kazakhstan, South Africa, and Zimbabwe. India, Kazakhstan, and South Africa accounted for 73 % of world production of chromite. The two largest producers of chromite, Kazakhstan and South Africa, were in the process of major economic and political change during 1993. South Africa's production and exports of chromite continued to fall during 1993, because of weak international demand and a flood of cheap metal from the former U.S.S.R. and China into world markets. Despite a significant increase in production, South Africa's ferrochrome producers continued to operate below capacity in 1993. Prior o the dissolution of the U.S.S.R., Kazakhstan was a major internal supplier of chromite ore to the U.S.S.R. consumer, but subsequent decline in demand led to a downward trend of chromite production in Kazakhstan and increasing exports to Europe during 1992 and 1993. The United States consumed, about 10% of world chromite ore production in various forms of imported materials. The United States imported nearly one-half of its required chromium contained in chromite ore and chromium ferroalloys and metal from South Africa; the remainder was from the minor producers Turkey, Yugoslavia, Zimbabwe, and others.

Jan 1, 1995

By A. C. Fieldner

The Bureau of Mines has recently conducted a study of results obtained in analyzing similar samples of coal and coke by 25 laboratories throughout then country, in comparison with results obtained in the Bureau's coal laboratory at Pittsburgh. The purpose of this work was primarily to obtain a comparison of the methods of coal analysis used by the laboratories of the American Gas Association. Therefore, four standard samples of coal end one of coke ware prepared in the Bureau of Mines coal laboratory at Pittsburgh, and portions sent to each laboratory. At the same time, a like number of standard samples were submitted to 12 commercial laboratories rot affiliated with the Association, for the purpose of comparing their analyses with the results is obtained by the U. S. Bureau of Mines and the American Gas Association. Tire comparison is based on the average of 24 analyses by the Bureau of Mines on each kind of coal, and the accompanying curves show the deviation from this average analysis, together with deviations from the check limits of the American Society for Testing Materials.

Jan 1, 1923

By Linda L. Chasko, Charles P. Lazzara, Ronald S. Conti, William J. Wiehagen

Fire has long been a concern for underground mine workers. A mine fire can occur at any time and can result in a partial or total evacuation of mine personnel and the loss of lives. Fires can grow rapidly. Time is the critical element. Prompt detection, timely and accurate warnings to those potentially affected, and a proficient response by underground miners can have a tremendous impact on the social and economic consequence of a small underground fire. Fire preparedness and response have components of technology and people. These components can work synergistically to reduce the time it takes to bring the system back in balance. This report deals with the preparedness of miners to respond to underground mine fires. It is intended to aid the mining industry in understanding the various roles of emergency responders and the training techniques used to increase their skill levels. The report also presents a technology overview to assist in effective response to mine fires.

By Karl C. Dean

The Bureau of Mines studied the precipitation of copper from dilute acidic sulfate solutions using shredded automobile scrap in a rotary drum. The tests established that the scrap in the rotary drum precipitated copper faster and more completely than shredded, detinned, tinplate scrap in a launder, with comparable iron consumption. Although power is required to rotate the drum, the faster precipitation and continuous recovery of cement copper are advantages of the tumbler method. Cost evaluation indicates that the rotary drum method, which uses relatively low-cost and readily available shredded automobile scrap, is competitive with the launder method, which uses relatively high-cost shredded tinplate scrap or detinned shredded cans.

Jan 1, 1968

By Daryl E. Radcliffe

Ninety-seven roof bolts were instrumented with strain gages and resin-grouted in three areas of the Bear coal mine, Somerset, Colo., by the Bureau of Mines. Measurements taken with these instruments indicate roof support is achieved through a combination of point suspension and resistance to vertical and horizontal stresses caused by localized shearing in the roof. The localized shearing results in bending of the bolts, yielding due to high vertical stresses, and the transfer of high loads to the bolt head or plate.

Jan 1, 1980

By Earl L. Phillips

The Bureau of Mines conducted laboratory tests on samples of pozzolanic-cement concrete to develop a low-strength backfill. Results show that support costs can be lowered by replacing a portion of the portland cement in mine backfill with pozzolan (fly ash) and lime. Unconfined compression tests on various ratios of fly ash to cement in 84 samples produced compressive-strength curves that can be used to estimate the best backfill mix for any mine.

Jan 1, 1981

By John J. Henn

An evaluation is presented for an ammonium sulfate leaching process designed to extract manganese from Cuyuna, Minn., and Aroostook, Maine, deposits. In this process the manganese and iron in the ore are reduced to MnO and Fe 3 0 4 in a shaft furnace; the reduced ore is then leached with ammonium sulfate solution forming soluble manganous sulfate while leaving most of the iron undissolved. After filtration, the manganese and some impurities are precipitated from solution as carbonates which are then pelletized and calcined to form a product composed mainly of Mn3O4. The plants are designed to produce 100 tons per day of manganese contained in a product that is suitable for the production of ferromanganese. A byproduct credit, together with the extra processing cost, is included for the Cuyuna ore processing plants because Fe2O3 may be recovered for use in blast furnaces. The estimated operating costs per ton of manganese, excluding income taxes and return on investment, are: [ ] The process with or without byproduct recovery, when treating Cuyuna or Aroostook ores, is not economically competitive with ores available at $71.43 per ton of contained manganese.

Jan 1, 1968

By A. Gene Collins

The Bureau of Mines conducted a research study of the geochemistry of the Smackover Formation to determine what geochemical relationships are useful in exploration for and production of oil and gas. Samples of oil, gas, brine, and rock were collected and analyzed. The oilfied brines were analyzed by methods recommended by the American Petroleum Institute and by tentative methods of the American Society for Testing and Materials. The crude oils were analyzed by Bureau of Mines methods; the gas, by Bureau of Mines methods; and the rocks, by wet-chemical, atomic absorption, and neutron activation methods. The results were correlated and interpreted, and several geochemical relationships useful in exploration and production were found. These include the type and class of brine, organic constituents in the brine, redox potential, in situ temperature and pressure of brine, degree of sulfate and carbonate saturation of brine, and halide concentrations in the brine.

Jan 1, 1974

By Stephen D. Cramer

The Bureau of Mines conducted a series of in situ linear polarization measurements in high-temperature, high-pressure hypersaline geothermal brines at the Bureau of Mines Geothermal Test Facility in the Imperial Valley of California. The measurements represented an evaluation of the linear polarization technique for obtaining instantaneous corrosion rates of materials of construction in flowing hypersaline hydrothermal fluids that rapidly form scales on exposed surfaces. A special method was devised for use with the linear polarization technique that resulted in obtaining corrosion rates for 1020 carbon steel, 316 and 430 stainless steel, titanium, various nickel-based alloys, and aluminum 6061 under strong scale-forming conditions. The measurements also provided information on scale-deposition rates in various geothermal environments. Exploratory in situ potentiostatic polarization measurements were made in the flowing brines to qualitatively determine scale-deposition effects on the electrochemical measurements.

Jan 1, 1978

By Sidney Katell

An estimated capital investment of $76,499,800 will be required for a plant designed and built to produce 90 million standard cubic feet per day (std.c.f.d.) of synthetic pipeline gas through Lurgi gasification of bituminous char. This investment figure does not include the pretreatment plant, the cost of which is assumed to be reflected in the cost of the char fed to the gasification system. Shift conversion, C02 removal, and methanation are required after gasification in the Lurgi unit to make a gas suitable for pipeline transmission. Capital investment data are based upon equipment costs, January 1959. Based on a 90-percent or 330-day operating year, the operating cost before profit and Federal taxes with the char price as a variable will amount to the following: [ ]

Jan 1, 1959

By J. Roger Loebenstein

Demand for arsenic exceeded supply in 1980, and the major domestic and foreign producers allocated available supplies to customers. Major demand was about evenly divided between industrial chemicals and agricultural chemicals. Legislation and Government Programs.-In June 1980, the Environmental Protection Agency (EPA) listed inorganic arsenic as a hazardous air pollutant.2 Proposed regulations on arsenic emissions were to be announced on an industry-by-industry basis at a future date, and public comment on the listing and on specific regulations was to be heard.

Jan 1, 1981

By B. J. Scheiner

As part of its mission to reduce pollution associated with mineral production, the Bureau of Mines is developing a dewatering technique for phosphatic clay waste that uses a flocculant, polyethylene oxide (PEO). This flocculant forms strong, stable flocs, which can be partially dewatered on a static screen and dewatered further on a rotary screen. Using this technique, a field test unit (FTU) was operated at a nominal 100 gal/min. Consolidated phosphatic clay material containing 20 percent solids was produced when feed slurries of 3 percent solids were treated with 0.69 pound of PEO per ton of feed solids. Pit and column tests indicated that the PEO-treated material continued to dewater; compacted products containing 40 percent solids were obtained after 45 days.

Jan 1, 1981

By Deborah A. Kramer

As part of the Nation's growing concern with the competitiveness of U.S. firms in the world economy, especially with respect to advanced materials, the Bureau of Mines assessed the actual and potential recovery and manufacturing capabilities for gallium and gallium arsenide (Gacis). GaAs has advanced from a laboratory curiosity to a material with important "high-tech applications within only the last few years, and although protected North American gallium supplies are currently considered adequate, consumption could grow to the point that this assessment would need reevaluation.

Jan 1, 1988

By J. M. Stuve

Calorimetric determinations of the low-temperature heat capacities, standard enthalpy of formation, and high-temperature enthalpies were made of (Na20)4 ?Fe20,(c). The resulting values of entropy (S°), enthalpy of formation (?Hf°), and free energy of formation (?Gf°) at 298.15° K are 104.676 cal/deg mole, -656.2 ±.kcal/mole, and -603.4 A kcal/mole, respectively. Tabulations of Cp°, S°, - (G°-H°298)/T, H°-H°298, ?Hf°, ?Gf°, and log Kf are given to 1,200° K.

Jan 1, 1971

By August J. Kwitowski

This Bureau of Mines report describes how the reinforcement mechanisms of untensioned, full-column resin bolts were determined during one underground study. Both axial and transverse shear loadings were identified for two instrumented resin bolts that replaced standard resin bolts in an opera-ting room-and-pillar mining section. The strain responses of resin bolt steel cores to local axial and transverse shear loadings are described. This information was obtained from laboratory testing of resin bolts installations; it was also used to analyze the data from the underground test.

Jan 1, 1980

By Everett A. Sondreal

Material and energy balances for stockpiled lignite were calculated by computer simulation techniques to determine the occurrence of spontaneous heating. Data on properties of lignite which affect spontaneous heating were required. In some cases, best values from reported data were utilized; in other cases, new data were developed. These include specific studies on the rate and conditions that influence oxidation, heat of oxidation, heat of wetting, specific heat, thermal conductivity, and permeability of stockpiles to air. These data are presented and discussed in detail for possible application to other studies. Results of computer simulations confirm past field experience on the storage of lignite containing as-mined moisture, and predict a greater risk of heat occurrence in stockpiles of dried lignite where experience is lacking. Successful storage was predicted for dried lignite of 20 pct moisture content, if it were cooled after drying and compacted to an interparticle void fraction of 9 pct (bulk density of 67 lb/cu ft) compared to 10 pet void fraction (72 lb/cu ft) for as-mined lignite.

Jan 1, 1974

By E. Chin

The mineral industry of Bangladesh was totally dominated by natural gas production and its downstream uses. A small amount of cement was produced, and clays were used locally for ceramics and construction materials. Nitrogenous fertilizer was produced from natural gas and a modest, scrap-based steel industry produced steel for local consumption. The country has been developing and using its abundant and inexpensive gas reserves as fast as practical. The population, however, was predominantly dependent on agriculture for its livelihood. The industrial sector accounted for 10% of the economy, and most of the industrial output was directly associated with agricultural products jute, tobacco, and textiles. Industrial expansion, even with the availability of gas, was severely constrained because of limited domestic demand, lack of skilled work force and management, poor infrastructure, and a low rate of domestic savings. To put greater emphasis on the industrial sector, the Government established a National Committee for Industrial Development in July. The Committee instituted policy reforms in the areas of trade and investment. One important step was to move from a positive import list to a negative list, thereby permitting imports of items not restricted or banned. The system for recovering and approving new domestic or foreign industrial investments was streamlined to expedite what had become a cumbersome, bureaucratic exercise. To encourage industrial development in areas away from the crowded urban centers, several economic incentives reportedly were adopted. These included a reduced tax rate on imported machinery, exemption of import license fees, a reasonable debt equity rate, and a 9-year income tax exemption period.2 In the trade sector, imports increased 12% in fiscal year (FY) 19843 mainly

Jan 1, 1987

By Philip C. Tully

The Bureau of Mines, in a continuing effort to improve processes and methods of helium purification, has developed a differential distillation method for removing helium-3 from helium-4. Differential distillation at 4.2 to 1.6 K was used to reduce the helium-3 in helium-4 from about 200 to less than 1 part per billion. The results from four stills ranging in size from 1 to 25 liters are reported. The method has the potential to be adapted to commercial-scale separations.

Jan 1, 1975