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By H. B. Freeman, E. J. Gleim

During the 12 months ended July 1, 1931, engineers of the Bureau of Mines examined electrical equipment in 80 bituminous-coal mines. The purpose of these examinations was to ascertain the condition of such equipment with respect to possible hazards of gas and dust ignitions, also of shock. Although only 3 of the 80 were being worked with open lights and therefore did not use explosion-proof equipment, there were others where electric cap lamps were used by the men but where it was apparently assumed that conditions as to gas and dust did not require equipment designed to give protection against ignitions. Early in its history the United States Bureau of Mines originated certain standards covering the construction and testing of electrical equipment in order to minimize the dangers of ignitions from exposed electric sparks and flashes ; accordingly, it is comparatively easy to determine wherein a machine built to these standards falls short of continuing to meet them if damaged or neglected. Many so-called flame-proof and dust-proof machines, however, have not been built to any standard comparable with that developed by the Bureau of Mines. In addition, certain machines have parts which pass Bureau of Mines tests, but do not satisfy the full requirements in other respects, and others make no pretense of inclosing the spark-producing parts. It is not uncommon to find two or more of these various types in the same mine with " permissible " machines, the type that has been built to conform to the Bureau of Mines standard. Consequently, inspection of nonpermissible machines becomes somewhat difficult without a standard of comparison. Because of its unprotected condition obviously open-type electrical equipment must be used with great care, if at all, in a mine where precautionary measures are adopted in guarding against gas and dust ignition. The unsafe nature of such equipment is widely recognized. For that reason it is to be installed only where there is no likelihood of gas being present. It is not apparent to some, however, why flame-proof and dust-proof equipment and equipment having tested parts should not be regarded in the same light as permissible equipment.

Jan 1, 1932

By T. J. Ballard

The Track Rock corundum mine was among the numerous corundum deposits investigated during the war by the Bureau of Mines in an effort to develop domestic reserves of that critical mineral. In the investigation of this property 562 feet of trenches were excavated and a l25-foot adit was reopened for the purpose of locating veins to of corundum which had been previously reported to occur in that locality. Only very minor amounts of corundum were disclosed in both the surface workings and the adit. The project was begun in May 1943 and completed in November 1943.

Jan 1, 1948

By Jack C. White

Studies were made to determine the character and distribution of the copper lost in copper mill tailings. Acid soluble (oxide) and acid insoluble (sulfide) copper were determined for heavy-liquid sink and float products of screen-sized fractions from 12 copper mill tailings. In most of the tailings studied, the coarse-size fractions are higher in copper grade than the respective bulk tailings, high in sulfide copper, and low in oxide copper. Oxide copper occurs predominantly in the minus 325-mesh "slimes." Microscopic examination of heavy-liquid sink products indicated that recovery of liberated copper sulfide minerals is complete in most mills, and that copper minerals not being recovered are locked with gangue particles. Additional copper could probably be recovered from most tailings by size classification, scavenger froth flotation of the coarse fraction, and regrinding of the concentrate to achieve liberation of the locked sulfides.

Jan 1, 1971

1.1 Bituminous-Coal and Lignite Dust. - Carboniferous material having a volatile ratio of 12 percent or more by weight and a fineness such that the material passes through a No. 20 sieve. 1.2 Active Underground Workings. - Underground places in which men are required to be or to pass through in the performance of normal mining operations for the production of coal. 1.3 Working Areas. - Underground areas where bituminous coal and lignite are mined, specifically: (a) Face. - The solid surface of the unbroken portion of the coalbed at the advancing end of the working place. (b) Face Area. - The working area inby the last open crosscut in an entry or a room, including the pillar being extracted or longwall being mined. (c) Room. - A place abutting an entry or airway where coal has been mined and extending from the entry or airway to a face. (d) Crosscut (Breakthrough). - Passageways or openings cut through a pillar to connect adjacent entries or rooms. 1.4 Entry. - Underground haulageways, travelways, and airways, except working areas as defined in section 1.3. (a) Active Entry. - An entry in which coal is being mined from a portion thereof or from connected sections. (b) Parallel Entry. - Usually an intake airway parallel to the haulageway. (c) Back Entry. - Usually a return airway parallel to the haulageway.

Jan 1, 1960

By D. W. Frommer

Laboratory mineral-dressing investigations were conducted on talc-bearing samples from Arkansas and Texas under the Bureau of Mines program of examinations and surveys, which is concerned, in part, with the improvement of conservation and utilization of domestic mineral resources. Two of the soapstones in question were successfully upgraded by flotation, utilizing stage additions of a frother and an amine to promote their talc content. The process could enable the producers to meet more rigid specifications of higher priced talc commodities. INTRODUCTION Talc is an industrial mineral with distinctive properties, such as softness, smoothness, large surface area in relation to mass, chemical inertness, and good retention as a filler, that make it particularly valuable to a number of industries. Sales to 6 industries -ceramics, paint, insecticide, rubber, roofing, and paper -consumed 84 percent of the domestic production of talc, pyrophyllite, and ground soapstone in 1952. Mine production in that year totaled 600,908 tons. Sales of crude and ground material were 593,147 tons valued at $11,347,317.2/

Jan 1, 1956

By W. W. Adams

During the calendar year 1927 the United States Bureau f Mines conducted, for the third consecutive year, a safety contest among more than 250 mines and quarries. Aside from its underlying purpose to promote safety, the object of the contest was to learn which mine or quarry had completed the year's work with the smallest proportionate loss of time from accidents to its employees. Competing companies were grouped into five classes, namely, anthracite mines, bituminous teal mines, metal mines, nonmetallic mineral mines, and quarries and open-pit mines. To the winning company in each group was awarded the bronze trophy "Sentinels of Safety," the gift of The Explosives Engineer magazine. The winner in each group was the mine or quarry whose record showed the smallest loss of time from accidents in proportion to the total amount of time worked by 411 employees. This proportion is designated the "accident-severity"3 rate; it indicates the number of days of disability resulting from personal injuries per thousand man-hours of work performed by all employees. Each company's standing was determined by the Bureau of Mines from detailed records furnished by the contestants. Records of the leading companies were made known to a committee of seven men well known to the mining industry but not connected with the Bureau of Mines. This committee selected the winning companies in accordance with rules governing the Competition. According to the contest rules, the competition for the trophy was restricted to mines employing at least 50 men underground and to quarries and open-pit mines employing at least 25 men in the pit. As several plants fell below these figures during the year, their records could not be considered in connection with the award of the trophy. Figures covering these plants are, however, included in the attached tables.

Jan 1, 1928

By Michael J. Brnich

Since 1991, Pittsburgh Research Center (PRC- formerly part of the Bureau of Mines) researchers have recorded extensive interviews with 30individuals who are experts in the area of mine emergency response. These individuals, who have an average of 35 years of mining experience and 29 years of mine emergency response experience, related stories and observations from events that they experienced during their combined 850 plus years in mine emergency response. The purpose of this effort was to gather information that could be passed onto both today?s and tomorrow?s mine emergency responders to train and guide them in handling future events. This is the second of two articles which report experts responses to questions about training for future mine emergencies. During the interviews they discussed how training should be conducted, who should be trained, and what topics should be included. This article will cover the third area: Topics that should be included in training for mine emergency response managers.

Jan 1, 1997

By J. W. Eckerd

Metal production rates of 42 to 45 tons per day were obtained with hollow-core anthracite briquets in an experimental blast furnace. Tuyere pressures were about the same for both coke and briquet operations, but from 150 to 175 pounds more of briquets were required per ton of metal than were needed with coke. Furnace operations were comparatively smooth, furnace hanging occurring less often than in previous tests with anthracite briquets. Dust production was substantially higher than with coke, however, and metal quality could not be controlled by corrective burdening and moisture control.

Jan 1, 1968

By William P. Diamond

A 3-inch pilot hole was directionally drilled to intercept the Freeport coalbed horizon horizontally at Mather, Pa., as part of a Bureau of Mines degasification project. The original concept was to continue the horizontal drilling into the coalbed, after the initial intercept, with a total of three horizontal holes eventually being completed. However, the erratic thickness (0.0 to 4.3 feet) of the Freeport coalbed at Mather was not sufficient to support the horizontal drilling degasification technique, and the site was abandoned after six attempts to locate adequate continuous coal thicknesses. The drilling of coreholes in the immediate vicinity of proposed well paths to evaluate coal thickness is essential prior to future slant hole operations. Although mechanical failures of the new directional drilling equipment, mud pump and rig breakdowns, directional control problems, and exploratory horizontal drilling in the Freeport horizon more than doubled the anticipated cost of the pilot hole, continuing improvements in directional drilling equipment and techniques should significantly reduce the time and costs of future drilling operations.

Jan 1, 1977

By John C. Edwards

The Bureau of Mines has developed a time-dependent droplet vaporization model (in the absence of forced convection) that can be applied to the vaporization of liquid Halon 1301 droplets (vapor pressure at 300 K = 14 atm) sprayed from an extinguisher. It was found that rapid surface vaporization quickly lowers the droplets' surface temperature very near to the boiling temperature, and the vaporization becomes diffusion controlled. Although the lifetime of the droplet is proportional to the square of the initial radius of the droplet, the elapsed time prior to complete droplet vaporization is not proportional to the square of the droplet radius, as an equilibrium model would indicate.

Jan 1, 1982

By Peter N. Gabby

A mineral survey of 8,300 acres of the 24,980-acre Burnt Creek Wilderness Study Area (ID 45-12), was conducted by the U.S. Bureau of Mines in 1985 at the request of the Bureau of Land Management. The study area is located in Custer County, ID, 90 miles northwest of Idaho Falls. No mines, claims, or prospects are in the study area. The northern half of the study area and adjacent lands to the north, northeast, and east are or were recently under oil and gas lease, Basalt and latite-andesite of the Challis Volcanics predominate in the study area. Several hundred feet east of the study area is a quarry in talus of Mississippian-age limestone that was used for sized 100-pound rock fill in the Old Dry Creek Reservoir dam. Two samples, one taken at the quarry and the other at a limestone outcrop on East Fork Burnt Creek, have CaC03 content in the range of 90 to 95 percent, and is suitable as the limestone component of Portland cement, However, limestone outside the study area could supply foreseeable demand. Lead- silver mineralization has been observed in Paleozoic carbonate rocks elsewhere in the Lost River Range, but these rocks do not occur in the study area.

Jan 1, 1986

By Donald O. Capstick

In 1981, U.S. Bureau of Mines personnel conducted a survey of claims and prospects in the Wheeler Ridge RARE II area to determine if mineral resources or potential for resources exists at deposits in the area. Results of Bureau of Mines investigations indicate the area contains no identified mineral deposits. However, the geologic setting at the Round Valley Peak Prospect near the center of the study area is considered to be favorable for the discovery of tungsten resources with associated molybdenum and copper. Tungsten deposits, should they be present, would be expected to occur at depth in tactite at or near the calcareous rock-granite intrusive contact. Sand, gravel, and stone deposits in the area are not considered to be resources because equal or better quality material is available closer to major markets. INTRODUCTION The 16,200-acre (6,560 ha) Wheeler Ridge study area is 11 mi (18 km) northwest of Bishop, California, on the eastern flank of the Sierra Nevada range. The John Muir Wilderness adjoins the study area's western boundary (fig. 1).

Jan 1, 1983

By Richard L. Rains

The 15,770-acre Worm Creek Roadless Study Area is in southeastern Idaho about 8 miles (mi) west of the northern portion of Bear Lake. U.S. Bureau of Mines personnel examined the roadless, area during the summer of 1984. No mineral resources were identified within the study area. There were no mines or mining claims in the study area in 1984. However, the study area is blanketed with oil and gas leases, but no known productive horizons have been identified within nor nearby. The roadless area is in the Cordilleran fold-thrust belt and is underlain by Paleozoic and Mesozoic marine strata more than 50,000 feet thick. The trace of the Paris thrust fault is 2 to 3 mi east of the study area and has an eastward displacement of about 4 to 7 mi.

Jan 1, 1985

By E. Morrice

Gadolinium, dysprosium, and yttrium are difficult to electrowin as high-purity liquid metals because of their high melting points (>1,300° C). Samarium metal is difficult to prepare directly by electrolysis because the metal reacts with the electrolyte. In this Bureau of Mines study, the rare-earth metal was electrodeposited on a solid manganese, chromium, or iron cathode to form a low-melting alloy. The alloy was then vacuum distilled to separate the rare-earth metal from the ferrous metal. A typical samarium metal product, obtained as the distillate from vacuum distillation of a samarium-iron alloy, contained 150 ppm oxygen, 80 ppm carbon, and 50 ppm iron as impurities, Gadolinium metal, obtained as a residue from the distillation of a gadolinium-chromium alloy, contained 300 ppm oxygen, 200 ppm carbon, and 100 ppm chromium.

Jan 1, 1969

By S. D. Maksimovic

The Bureau of Mines evaluated the hydraulic stimulation of a gob-degasification borehole to determine if this procedure would aid in degasifying a longwall panel. The stimulated borehole did not degasify the longwall panel as expected either before or after mining of the panel started. It reduced the underground methane emission only 11 pct, considerably less than the reductions effected by two unstimulated boreholes in the same panel. Some probable reasons for the reduced methane flow from the hydraulically stimulated borehole are very low reservoir gas pressure, location of hydraulically stimulated zones within the grouted casing, a casing break caused by lateral shifting, possible vertical movement of rock strata during caving, grouting of a 4-inch pipe blocking three stimulated zones, plasticity of shales, and possible hole damage by swelling of water-sensitive minerals. The borehole was also located between two second-mined areas, which may have allowed partial degasification of the overburden and the coalbed in advance of mining. Finally, a period of 3 months is probably not long enough for the borehole to degasify the overburden before mining.

Jan 1, 1977

By R. D. Leitch

The pollution of streams by acid mine drainage has become of great importance in the past few years in certain regions of the United States. Large quantities of acids are used in a discharged from other industries than mining, notably in tube, sheet, tin-plate and era hell inn works. These are usually less important then coal mines as a source of acid drainage, because of their more limited distribution throughout the States most affected by acid waters and their relatively smaller numbers. Streams are naturally alkaline and are, therefore, able to take care of rather large quantities of acid wastes, but when such enormous quantities as are often found in mining districts enter the streams, the natural alkalinity is quickly overcome. When a neutral or almost neutral condition has been reached, the further addition of a relatively slight quantity of acids will cause a great difference in the quality of the water.

Jan 1, 1926

By Rose L. Ballard

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are the tables that show the principal nonfuel mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is ordinarily termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines.

Jan 1, 1982

By Gary P. Sames

This report discusses some practical applications of a geotechnical investigation conducted by the U.S. Bureau of Mines that can help mine operators meet revised Federal regulations in their roof control plans. The investigation, designed to characterize roof conditions near the coalbed outcrop in drift coal mines in eastern Kentucky, revealed that weathered stress-relief joints near outcrop are crucial ground control factors in the region. The joints' origin and character were determined through underground mapping of many joints in coal mine roof and detailed observations and measurement of joint trends and physical characteristics in widely separated strip mine highwalls and roadcuts. This resulted in an understanding of stress-relief-joint patterns and the effect of various rock types on the intensity of weathering in the joints. That information is used in this report to show how stress-relief joints contribute to roof failure and how, through improved roof support and mine planning, safer roof support plans can be developed.

Jan 1, 1992

By D. G. Kesterke

Research was conducted to determine the feasibility of extracting elemental oxygen from silicate-bearing melts by high-temperature electrolysis. The method was based on a modification of existing processes for electrowinning metals from their oxides dissolved in molten halide systems. Electrolyses were performed at temperatures ranging from 1,050° to 1,250° C in boron nitride cells that incorporated a silicon carbide cathode and an iridium anode. The electrolytes contained volcanic scoria as the oxygen source, plus mixtures of BaF2 and LiF as fluxing agents. Cell gases containing almost 14 volume-percent oxygen were obtained. The average anode current efficiency for several experiments of extended duration was calculated to be 55 percent. Cell design and operating conditions are described, and some of the problems associated with the process are discussed.

Jan 1, 1971

By Ronald D. Hill, Elmore C. Grim

The United States is richly endowed with mineral resources. However, mineral recovery by its very nature, involves a destructive process, Figures 1 and 2. In the past, mining practices were all too often conducted with the purpose of removing minerals by the simplest and cheapest method possible, without plans for the preservation of land, water, and air, and with too little consideration for the rights of others. A mining company is in business to make a profit, but every company, regardless of the nature of its business, has moral obligations to reduce its undesirable effects on the environment and to safeguard the rights of others. The problem of environmental degradation caused by surface mining is widespread and serious. Minerals in some form occur in each of the 50 States and several States are extensively mined. Data on the acreage disturbed in the United States, by commodity and State are presented in Table 1. Thirty-one States have laws regulating surface mining, (Table 2). Briefly reviewed in Appendix A-1 are the basic provisions of State laws governing surface mining. It can be seen that these laws vary considerably from State to State owing largely to the mining conditions within that State. Of the 24 coal-producing States, only three (Alaska, Arizona, and Utah) do not regulate strip mining. Even the states that are often cited as models of comprehensive regulations still have problems minimizing environmental damages. Uncontrolled surface mining presents a situation as critical to the well-being of the society as any it has ever faced. Many mining activities have imposed huge social costs on the public at large. These costs are long-range and are in the form of stream pollution, floods, landslides, loss of fish and wildlife habitats, unreclaimed land, erosion, and the impairment of natural beauty. In a 1965 Department of Interior study,(1)it was estimated that of the 25,000 miles (1+0,225 kilometers) of contour bench in Appalachia, approximately 1,700 miles (2735 kilometers) are affected by massive landslides. Additionally, 1+800 miles (7723 kilometers) of streams and 29,000 surface acres (11,716 hectares) of impoundments and reservoirs have been seriously affected by coal strip mining operations in the United States.

Jan 1, 1974