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By Charles L. Kimbell

The year 1979 was a period of increased activity for the world's mineral industry, distinctly in contrast with 1978 when estimated world crude mineral output value declined slightly and most phases of the industry's activity were somewhat curtailed. In 1979, most major mineral commodities recorded significant gains in output, with a substantial number achieving new record highs; details on trade levels for 1979 were not available, but increases over those of 1978 were expected on the basis of partial data. Consumption of most commodities edged higher; in some cases the higher demand levels were met largely through draw-downs of stocks accumulated in recent years, while in other cases notable output increases were required to meet demand. Actually, 1978 was not a bad year for all elements of the mineral industry if changes in output levels of the various commodities are considered as a measure of performance. There were far more individual commodities registering production increases between 1977 and 1978 than registered declines, but some of those reported as declining were relatively major commodities (bauxite, aluminum, copper and zinc were notable), Moreover, the upturn in productive activity in 1978 was not matched by increases in profits. However, 1979 was unquestionably a year of renewed expansion efforts, although some commodity areas, most notably the steel industry component, were still experiencing difficulties.

Jan 1, 1981

By Charles L. Kimbell

For the world mineral industry as a whole, the year 1981 was a period of continuation and, in some instances, an acceleration of negative trends extending back into 1980. Most available statistical data reflected stagnation or downturns in activity. Levels of production, trade, and consumption declined for a substantial number of leading mineral commodities, including, most notably, steel and petroleum. Investment, if not lower than in 1980, was evidently increasing at a more modest rate. Prices for major mineral commodities were generally lower, at least in terms of constant dollars, and in some cases even in terms of current dollars. Prospects of a major reversal of these patterns seemed dim. The mineral industry, however, was far from alone in this general downturn; most other elements of the national economies of the world's nations fared little better. General conditions of inflation, recession, and reduced industrial product consumption were reflected in most other sectors of the total economy. International political events continued to influence mineral output and flow but had less influence on overall levels of activities than on the geographic distribution of these activities. The Iran-Iraq war certainly played a role in reducing mineral industry activities in those nations, but the commodity most affected, petroleum, was available from other sources in sufficient quantity that, in the face of reduced demand, a substantial surplus developed.

Jan 1, 1983

By W. H. Young

In response to increasing national energy requirements. highlighted by the continuing growth in demand for coal for the generation of electric power the output of bituminous coal and lignite in 1965 passed the 500-million-ton mark for the first time since 1956, thus emphasizing the steady up-ward trend from the recent low of 403 million tons in 1961. There were corresponding upward trends in consumption, exports mechanization, and productivity. Production.-The output of bituminous coal and lignite in the United States in 1965-512 million tons-was 5 percent greater than the 487 million tons produced in 1964. The gain was attributed largely to expanded consumption by the electric utilities, greater use at coke ovens, and an increase in exports.

Jan 1, 1967

By M. J. Mechling, H. J. Sloman

"INTRODUCTION The practicability of providing safer methods of underground transportation for mine workmen and officials has been given much thought in recent years by advocates of safety, health, and efficiency. Numerous fatalities and disabling injuries have resulted from falls of roof, personal contact with both electrical conductors and timbers, and improper position or conduct of passengers while they were in man-trips. Unfavorable atmospheric exposure due to high-velocity air currents and sudden changes in temperature may adversely affect the health of mine workmen if they are transported in unprotected Cars.Recent installations of protected, man-trip cars, wherein such cars have been utilized to haul men to and from their stations in the mine, have resulted in a large reduction in exposure to haulage hazards. Where special-built cars have been used the probability of injuries to men during transportation in man-trips has been decreased, and the morale of the employees has been improved. A number of man-trip cars are in service in the coal-mining regions; those described in this circular are typical examples of a few installations."

Feb 1, 1948

The investigations reported herein comprise preliminary studies to evaluate large scale mining systems adaptable to the thicker oil shale deposits in the deeper central portion of the Piceance Creek Basin. The studies include an evaluation of the geology, hydrology and resources of the Basin., evaluation of a potential prototype mine site, synthesis of rock mechanics data on Green River Formation oil shale, selection and preliminary design and cost evaluation of six potential mining systems and a ranking analysis to aid in selecting the most promising system. Results of the ranking analysis indicate the following four systems to be most promising for large scale underground oil shale mining: - Chamber and pillar (using spent shale backfill) - Sublevel stoping with spent shale backfill - Sublevel stoping with full subsidence - Block caving with LHD's Recommendations for phase II are to investigate the above systems in greater detail, refine present cost data, and perform economic evaluations of oil shale mining using these systems.

Jan 1, 1975

By Robert B. Hoekzema

The Bureau of Mines and U.S. Geological Survey completed a 4-yr (1979-82) mineral appraisal of the Chugach National Forest (CNF), AK. This report summarizes the Bureau's placer gold studies in the CNF. Placer mining from the mid-1890's through 1982 produced an estimated 133,800 oz of gold, of which two-thirds was produced prior to 1920. As much as 6,800 oz of placer gold was produced from 1979 to 1982. Most production came from Crow, Canyon, and Resurrection Creeks. Five types of placer gold deposits were identified in the CNF: (1) alluvial placers, (2) bench placers, (3) eluvial placers, (4) glacial placers, and (5) marine placers. Placer sampling indicated a potential for gold production from alluvial and bench placers associated with historically mined drainages such as Crow, Canyon, Resurrection, Sixmile, and Mills Creeks and from unmined drainages including the Avery, Kings, Snow, Copper, and Tasnuna Rivers and several smaller streams throughout the CNF. Results of fineness tests indicated that gold from the CNF ranges from 455 to over 950 fine. Subsequent investigations in drainages with anomalous placer sample values also identified previously unknown lode mineralization.

Jan 1, 1986

By D. Z. Hobbs

Because an economic method for preparing pure boron has not been developed, a program was started by the Bureau of Mines to evaluate existing techniques or to develop new methods for preparing the pure element. This report describes investigations directed toward the development of techniques for the preparation of pure boron by fused-salt electrolysis. Only two of the several fused-salt baths tested were satisfactory for the preparation of boron. These baths contained (1) potassium fluoride, lithium fluoride, potassium fluoborate and boron trioxide; and (2) potassium fluoride, potassium chloride, and boron trioxide. Of these two mixtures, the latter was more satisfactory. Elemental boron of from 90- to 95-percent purity and, in isolated cases, as high as 98-percent purity, was prepared from these two types of fused-salt baths. There appeared to be no distinct differences either in the yields or the purity of boron prepared at current densities ranging from 795 to 1,000 amperes per square foot. Current efficiencies were as high as 85 percent.

Jan 1, 1961

By Robert F. Chaiken

The U.S. Bureau of Mines conducted an experimental and theoretical study of coupled chemical kinetic and mass transport processes during leaching of pyrite from coal in a counterflow, "trickle-bed" column reactor. Spatial and temporal data on reactant and product concentrations were used as solutions to appropriate continuity equations, which in turn define chemical kinetic reaction rates. Data from four 180-by 30-cm column leaching experiments using coal, coal waste, and air-water and air-FeC13 lixiviants have been analyzed. The rate of leaching was found to be diffusion limited (probably by Fe3+) and not controlled by bacterial action. Rates of pyrite oxidation were found to vary with elapsed time (80 to 225 days) and followed a bell-shaped curve, sometimes with a delay before start of reaction. Maximum rates of reaction ranged from 3 to 10 (mmol/d)/L (column) for coal waste and 0.4 (mmol/d)/L (column) for coal. Reaction was 30 to SO pct complete, probably due to precipitation of product salts (e.g., jarosites), which impede transport of oxidant through the coal. An absorption-desorption model of solids leaching, which considers the role of heterogeneous porosity in solids leaching, was used to describe time-dependent leaching rates.

Jan 1, 2010

By Krishna P. Sinha

An investigation was made to determine the creep behavior of oil shale at elevated temperatures. During the first phase of the investigation, work done on creep behavior of geologic materials was reviewed and triaxial creep tests on oil shale were planned. Tests at temperatures up to 250°C and axial stress up to 3000 psi were conducted at no confinement and at confining pressures equal to 1/3 and 2/3 of axial stress. Wide variations in the elastic properties as well as creep characteristics are exhibited. Creep deformation is more pronounced at elevated temperature but no definite quantitative remarks can be made regarding effect of grade of oil shale due to wide scatter and limited number of data paints. Primary creep can be described by a power law. Secondary creep seems to be an experimental function of deviatoric stress. Teritary creep was not observed within the test duration (24 hours in most tests).

Jan 1, 1983

By T. E. Green, E. F. Spano, W. J. Campbell

A combined ion - exchange X- ray spectrographic method was developed and evaluated for determining trace amounts of cobalt and nickel in high - purity tungsten and tungsten trioxide . The sensitivity for both cobalt and nickel is in the range from 0.2 to 0.5 μg ( 0.04 to 0.1 ppm , based on 5 gram samples ) . Accuracy at the 5 to 20 μg level is ±10 percent of the amount present . Approximately 16 hours elapsed time is required for analysis

Jan 1, 1963

By J. W. Thompson

LIMESTONE DEPOSITS. Limestone deposits that have not been demonstrated to be of such quality as to give them any substantial value over other limestone deposits of the same region, are not regarded as minerals. Gray Trust Co., In re, 47 Land Decisions 18, p. 20. OIL AS A MINERAL. Oil is a mineral substance and its removal will greatly impair the value of the land from which it is removed. Texas & Pacific Coal & Oil Co. v. Howard. Southwestern 735, p. 737. Tex. Clv. App. 212 OIL AND GAS AS MINERALS OWNERSHIP. Oil and gas are minerals and so long as they remain in place they belong to the owner of the land under which they are found and such owner has the right to explore for the oil and gas on or under his land and when found to remove and possess the same. Kimbley v. Luckey, Okla. - 179 Pacific 928, p. 831. OWNERSHIP OF MINERALS LACHES NO BAR. The owner of minerals in land can not be barred by laches for failing to assert his ownership where his title had not been ques- tioned and his right invaded. No lapse of time bars one's right to property and it is only in case his right has been invaded that it can be barred by laches.

Jan 1, 1920

By Louis A. Panek

Tests of mine-roof models in a centrifuge show that the suspension effect due to bolting a horizontally bedded mine roof with frictionless surfaces of contact between beds depends principally on the number of bolted beds and their relative flexural rigidities, provided that sufficient bolt tension is exerted to prevent strata separations at the bolt locations. Strata separations tend to occur in the unbolted roof mainly because the beds have unequal thicknesses. "Suspension effect" refers to the transfer of part of the weight of weaker or thinner beds to the flexurally more rigid beds by roof bolts or by any other means. The factors investigated were number of beds in the bolted unit, bed thickness, modulus of elasticity of beds, length of bolts, spacing of bolts across and along the opening, bolt load, and intensity of roof load. The general principles of behavior of the bolted roof beds are explained by an approximate theory. Model test data are used to validate the theory and to obtain an expression for the "suspension efficiency". As the suspension effect actually observed in the models is smaller than that predicted by the approximate theory, the suspension efficiency in general is less than unity. Mathematical expressions are obtained for (1) the change in roof bending stress due to the suspension effect, which is needed for design of a roof-bolting system, (2) the change of roof deflection due to the suspension effect, which may be useful for evaluating the effectiveness of a roof-bolting system, and (3) the bolt load or pre-load that is required to achieve the desired reinforcing effect.

Jan 1, 1962

By H. D. Bemis

This paper describing the milling practice of the American Metal Co. at its Pecos con¬centrator is one of a series on milling methods and costs being prepared by the United States Bureau of Mines. ACKNOWLEDGMENT The author acknowledges the assistance rendered by Guy Martin, metallurgist, H. E. Brown and J. H. Hastings, chemists, and Thomas J. Fahey, accountant, in gathering and pre¬paring the data presented in this paper.

Jan 1, 1932

By L. A. Stewart

"SUMMARYThis paper describes most of the chrysotile-asbestos deposits of Arizona. Mining methods are discussed briefly and asbestos-mill flowsheets are incorporated. Arizona asbestos mines are the only sources on the American continents of naturally iron-free chrysotile spinning fiber that is so urgently needed for electric-cable coverings, especially on warships.Asbestos was first recorded and recognized in Arizona in 1872, and a minor amount was produced from a deposit in the Grand Canyon in 1900. The discovery of a deposit in the Salt River district in 1912 initiated intensive prospecting, and deposits soon were developed. The total Arizona production of all grades of asbestos through 1953 is estimated at 30,000 to 35,000 tons.The deposits of the Central Arizona region, which are discussed in this paper, are scattered over nearly 2,000 square miles. The annual output is relatively small, because the asbestos occurs in thin, discontinuous veins and only in areas where intrusions of diabase are adjacent to or crosscut certain favorable units of the pre-Cambrian Mescal limestone. This stratigraphic limitation, combined with other essential geologic conditions, tends to restrict the size of the deposits.Virtually all of the deposits are in rugged, mountainous country, and many of the mines are on steep canyon walls. In the average mine, production of 1 ton of commercial asbestos requires removal of 30 to 40 tons of waste rock. Mining and transportation costs consequently are high.Several deposits of chrysotile that is somewhat harsh and of moderate tensile strength have been known for years but were not worked because of the former exacting demands of industry for high-strength, soft asbestos. However, improve¬ments in asbestos fiberization and spinning technique, combined with the urgent need for asbestos, have made this so-called semisoft fiber desirable, and deposits of this type now are being exploited."

Jan 1, 1955

By C. Harry Benedict

This paper presents the details of milling practice and costs at the conglomerate mill of the Calumet & Hecla Consolidated Copper Co., Lake Linden, Mich., and is one of a series on milling methods being published by the Bureau of Mines. GENERAL DESCRIPTION The mines of the Calumet & Hecla. Consolidated Copper Co. are located in the Keweenaw Peninsula of northern Michigan. The mines of this district lie in a belt not over 4 miles wide and 100 miles long, which contains more or lees commercial ore. The Calumet & Hecla properties are the farthest north, except for the Seneca, of the operating mines. The district borders on Lake Superior, and by means of the Portage and Torch Lake waterways the largest lane vessels, can transport coal and other supplies from the lower Lakes directly to the company docks.

Jan 1, 1930

By Walter E. Lewis

Ventilation-air-heating plants are in use at several iron mines on the Menominee Iron Range, Iron River, Mich. Many of the mines are exceptionally wet; during winter months, when fresh air is forced down the wet air shafts into the mine, it is usually necessary to heat the fresh air to above freezing so that the openings will not be closed by ice. The problem of ice closing air shafts has been solved by the practice of reversing the air current before the openings have become completely closed. This procedure involves drawing warm air from the mine up the usual down-draft air shaft. The M. A. Hanna Co. has found, at some of their mines on the Menominee Range, that it is more convenient to heat the below-freezing air rather than reverse the air current. Intermittent freezing and thawing of ice that has formed in the air shaft tends to loosen the wall rock, requiring major shaft repairs. The openings are kept free of ice the year around by heating the fresh air during periods of below-freezing weather. Table 1 shows the monthly minimum moan, maximum mean, and mean temperatures for the Iron River area. Under normal conditions of temperature, the furnaces are fired in November and usually are not allowed to go out until April of the following year.

Jan 1, 1951

By Christopher Mark, Robert J. Tuchman

This proceedings volume contains papers presented at technology transfer seminars sponsored by the National Institute for Occupational Safety and Health (NIOSH) on New Technology for Ground Control in Retreat Mining. The seminars were conducted at five locations: Uniontown, PA (March 26, 1997), Norton, VA (April 8, 1997), Pikeville, KY (April 10, 1997), Charleston, WV (April 17, 1997), and Evansville, IN (April 22, 1997). The papers presented here describe several new, highly practical technologies developed by the NIOSH Pittsburgh and Spokane Research Centers3 to improve safety during pillar retreat operations. Two central issues are addressed: pillar design and mobile roof supports (MRS's). Proper pillar sizing is essential for safe pillar extraction. The Analysis of Retreat Mining Pillar Stability (ARMPS) program and its large data base of actual mining case histories are presented. LAMODEL, a second computer program, can be used for analysis of multiple-seam and other complex mining situations. Other papers address pillar design to avoid massive pillar collapses and the proper role of coal strength testing. MRS's have greatly improved safety where they are used for pillar line support. We studied the application of MRS's at 20 mines throughout the Eastern United States. Conclusions regarding the most effective section layouts, cut sequences, and support placements are reported. Field and laboratory tests of MRS's are also described.

Jan 1, 1997

By James C. Barker

Gold placer deposits along the upper Yukon River, in the region between the river villages of Circle and Eagle, were investigated by the Bureau of Mines. The investigation was conducted intermittently between 1976 and 1985 as part of an evaluation of mineral resources on lands proposed for inclusion in the National Park System. At least 230,000 troy ounces (tr oz) of gold has been produced in the region, principally from Woodchopper, Goal, and Fourth of July Greeks. The placers are underlain by, or occur downstream of, early Tertiary sediments that have been deposited in the Eagle Trough. Strike-slip displacement along the Tintina Fault is responsible for creation of the trough and may have been a factor in the formation of the present placers. Placers were found to have a close spatial correlation to certain altered fault lineaments of the Tintina Fault trench. Placer concentrates contain several different textural forms of gold, suggesting multiple origins. Geological studies and a survey of 162 panned concentrates throughout the region indicated previously unreported sites of placer gold, and potential exists for the discovery of additional placer and lode gold. Because of nearly continuous soil and vegetation cover, further evaluation of the region will require subsurface sampling.

Jan 1, 1986

By G. E. McClelland

As part of its mission to assure an adequate domestic supply of metals essential to the Nation's welfare, the U.S. Department of the Interior, Bureau of Mines, investigated a particle agglomeration technique as a means for improving the flow of leaching solution through heaps of clayey or finely crushed, low-grade, gold-silver ores. Bench-and pilot-scale experiments showed that the percolation rate of cyanide leaching solution was markedly enhanced by mixing the ore with a portland cement binder, moistening the mixture, and mechanically agglomerating and aging the feed prior to heap building and leaching. The rate of gold and silver recovery markedly increased because of the increased, uniform percolation of leaching solution through the agglomerated feed. The use of concentrated cyanide solution instead of water during the agglomeration procedure decreased the leaching time required to obtain maximum recovery. Results of bench-and pilot-scale experiments are discussed.

Jan 1, 1981

By W. J. Wenger

Results of the analyses of 151 crude oils from 123 oilfields in the Williston basin are presented. Production statistics are compiled by geographical areas within the basin, by geological age of the producing zones, by States, and by field for the nine fields with the greatest production. Characteristics of the oils are tabulated, and correlations are included to show relationships between properties of the oils and some factors in the environment. Properties of the oils in some instances imply that there has been migration and mixing of the oils between productive formations of different geological time periods.

Jan 1, 1968