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1. In 2002, a total of 7,125 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA). The largest percentage of all mining sectors1 was sand and gravel mines (49.1%). Sand and gravel mines are found throughout all 50 states.

Jan 1, 2004

1. In 2002, a total of 763 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Examples of nonmetal mining operations include the mining of clay, trona, barite, phosphate rock, gypsum, talc, gemstones, and pumice. Nonmetal mines comprised 5.3% of all mining operations. • Nonmetal mining operations are located in all but nine states or territories (Alaska, Delaware, Maine, New Hampshire, Rhode Island, Vermont, Wisconsin, Puerto Rico, and the Virgin Islands). • Mines producing common clay comprised 29.2% (n = 223) of all nonmetal mining operations.

Jan 1, 2004

1. In 2002, a total of 4,311 stone mining operations reported employment to the Mine Safety and Health Administration (MSHA). The major industrial classifications in stone mining are dimension stone (used for construction purposes), crushed and broken stone (aggregates), cement, and lime. Stone mines comprised 29.7% of all mining operations. • Mines producing crushed and broken stone (n = 3,372) comprised 78.2% of all stone mining operations.

Jan 1, 2004

By Robert C. Ellman

The Bureau of Mines studied lignite pulverization in a laboratory ring-roller mill. Both moisture content and the source of lignite were found to be important factors in pulverizer operation. Reduction of moisture content increased capacity and reduced power consumption, but predrying is more effective than in-the-mill drying in improving pulverizer operation. A combination predrier-crusher system produced significant improvements but other efforts to improve in-the-mill drying in the test mill were unsuccessful. Pulverization of frozen lignite was found to seriously reduce pulverizer capacity and increase power requirements.

Jan 1, 1972

By Wilbur I. Duvall

Nineteen quarry blasts were instrumented with particle-velocity gages mounted in a uniform soil overburden, back of one face in a quarry in Iowa. Three components of particle velocity, radial, vertical, and transverse, were recorded at each of eight stations back of each blast. Distances from blast area to gage stations ranged from 150 to 3,000 feet. Eleven of the quarry blasts employed millisecond delays, and eight were instantaneous blasts. Charge weight per hole was 200 pounds, and the charge weight per delay interval, including the instantaneous blasts, ranged from 100 to 3,000 pounds. Analysis of the data from these tests shows that the particle velocity, V, produced at distance, D, by a quarry blast of charge per delay interval, W, can be represented by an equation of the form, V=KWb D-n, where b and n are exponents, and K is the intercept constant which is a measure of the level of vibration. The value of K for a millisecond-delayed blast employing one hole per delay interval is about 42 percent larger than the value of K for a single-hole blast. The value of K for a multiple-hole milli-second-delayed blast is about the same as that for an instantaneous blast when the charge per delay for the millisecond blast is equal to the total charge for the instanteneous blast. The vibration level from millisecond-delayed blasts employing one hole per delay is shown to be independent of the length of the delay interval and the number of delay intervals over the range of the variables tested: 9, 17, and 34 milliseconds and 3, 7, and 15 delays per blast.

Jan 1, 1963

By E. D. Calvert

As part of its goal to minimize the requirements for critical and strategic minerals, the Bureau of Mines is conducting research to foster the use of domestically abundant materials such as molybdenum. This report describes the development of an investment shell molding technique that can be used to make castings of molybdenum and its alloys. The mold material is cubic Zr02 with a monoclinic Zr02 binder. The shell, formed by standard investment molding techniques described in the text, is prepared for molybdenum casting by firing for 6 hours at 1,550° C (2,822° F) or for 4 hours at 1,650° C (3,002° F). The resulting castings have predictable and reproducible dimensions with good detail. As-cast strength is poorer than the strength of wrought materials below 1,600° F. At and above this temperature, tensile strengths of cast and wrought materials are nearly equal. Aqueous corrosion of the castings in most media is insignificant.

Jan 1, 1982

To reduce operator exposure to drilling noise from roof bolting machines. Background Noise-induced hearing loss (NIHL) is a prevalent occupational illness in the United States. Studies indicate that 70%?90% of miners have NIHL significant enough to be classified as a hearing disability. Mine Safety and Health Administration studies indicated that roof bolting machine operators are among those overexposed to noise. Field studies support the premise that, on average, drilling is the loudest noise source to which a roof bolting machine operator is typically exposed and contributes greatly to the operator?s noise exposure. The National Institute for Occupational Safety and Health (NIOSH) has further determined that the drill steel and chuck radiate a significant amount of noise during drilling. To address this noise hazard, NIOSH developed a collapsible drill steel enclosure (CDSE) to encapsulate the drill steel during the drilling portion of the roof bolting machine duty cycle. In addition, NIOSH is collaborating with J. H. Fletcher & Co. in the continued development of a CDSE.

Sep 1, 2008

Objective: To enable mine operators and mine inspectors to make quick and accurate measurements of the explosible nature of coal and rock dust mixtures.

Jul 1, 2008

Experience, it is said, is the best teacher. Some experiences, however, should be shared so that no one else will ever have to live through them again. The fire at the Sunshine Mine is one such experience. ?Hard-rock mines don?t burn.? The Sunshine Mine near Kellogg, ID, was the nation?s premier silver producer for many years. In 1972, the mine was nearly 6,000 feet deep, contained hundreds of miles of worked-out areas, and employed nearly 500 people. Because of its depth and the type of host rock for the silver (unburnable quartzite), the general thinking of the day was that fires in mines such as the Sunshine were impossible, because ?hard-rock mines don?t burn.? What wasn?t really considered was that timber supports, foam insulation, and mining equipment do burn and that the carbon monoxide gas produced by burning is far more deadly than fire itself. Thus, no one was prepared when, on May 2, 1972, a fire of un-known origin broke out below the 3100 level of the mine. Before long, 173 miners on the day shift were trapped by thick, black smoke. By the time the fire was out, 91 miners had died, and the Sunshine Mine Fire became known as one of the worst mine disasters of the 20th century. It became the catalyst for passage of the Metal/Nonmetal Health and Safety Act of 1977, which applied the same federal safety standards to hard-rock mines as those regulating coal. Mandated safety training, mine inspections, and equipment standards were brought into force.

Aug 1, 2002

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Mine ventilation can be broadly defined as the branch of mining engineering primarily concerned with the controlled flow of air through mine airways to maintain an acceptable atmospheric environment wherever men work or travel underground. Martinson (1976) has defined three elements of mine ventilation, 1) an engineering element concerned with establishing quality control (removal of dust and gases), quantity control (regula¬tion of air direction and magnitude) and climatic conditioning (temperature-humidity control), 2) a biological element in which an understanding of biological response is used in assessing the mine environment, and 3) a philosophical element requiring judgements as to the degree of risk or worker discomfort that is socially acceptable. Most texts on ventilation, such as Hartman (1961), limit themselves to a discussion of the engineering element. Although also limiting his text to engineering control, Weeks (1928) thoughtfully addresses the other elements in the preface of his book where he states: "Life is brief and happiness elusive under the best of conditions; so beside the commercial aspect must be placed the humanitarian. Is it not reasonable that the operator should give his men a chance to spend their working hours in a comfortable environment, with the danger of sudden death or disability reduced as much as possible?" The statutory requirements of ventilation are, in most countries, established on the basis of biological response as determined by basic research or are dictated by social awareness, often touched off by major disasters, resulting in demands on regulatory bodies for more stringent requirements. To a limited extent, the philosophical and biological elements of ventilation are intertwined in that social awareness may

Jan 1, 1977

By J. J. Bourquin, S. H. Katz

"Three types of respiratory apparatus namely, gas masks, hose masks, and self-contained oxygen-breathing apparatus - are now commonly used for protection from noxious gases, vapors, and smokes or ristes, but no particular type can be selected as best for all conditions. Many factors must be considered in connection with each situation, so that each must be considered as a problem in itself. Following are concise statements for comparing the types:Gas masks are the simplest and easiest to wear, also the least cumber-sore; but they protect only in comparatively low concentrations of noxious gases and should never be used where the air contains less than 16 per cent of oxygen. Special masks give protection from one gas or class of gases, but may give no protection against another gas or class of gases.Hose masks protect in any irrespirable atmosphere, but are somewhat cumbersome, the length of hose limiting the distance a wearer may go from fresh air. They are serviceable also where a supply of pure air moves with the wearer, as where a locomotive engineer in a smoky tunnel is using a hose mask supplied with air from the compressed air line of the locomotive. Hose masks consume no chemicals or materials and so are not limited in the time they may be used.Self-contained oxygen-breathing apparatus protect in any irrespirable atmosphere, but their weight is cumbersome, they can be used only by trained men, and frequent attention must be given them to maintain good working condition. On the other band they are the only safe means for exploring mines and other places filled with irrespirable gases in high concentrations."

Jun 1, 1923

By B. W. Jong

As part of the Bureau of Mines program to develop substitute or improved performance refractory materials for metallurgical applications, the Tuscaloosa Research Center has evaluated the effect of additives on sintering and strength properties of aialon (silicon aluminum oxynitride) compositions fabricated by a conventional powder metallurgy technique. Additions of Y203, Gd203, CeO2, MgO, ZrO2, ZrSiO4, and MgA12O4 to a sialon composition containing 70 pct ß-Si3N4 + 30 pct a-A1203 increased sintered densities by as much as 50 pct over densities of undoped material. The studies also indicated that sintered densities reached a maximum between 20 and 30 mole-pct a-A1203 when a series of sialon compositions of a-Si3N4, having 6.7 to 57.9 pet a-Al203, were doped with Y203, Gd2O3, and MgO. In studies to establish the effect of the crystalline phase of the silicon nitride and alumina used, tests were made using a- and ß-Si3N4 and a- and ?-A12 03 as starting materials. The tests indicated that when using an addition of 5 wt-pct Y203, best results were obtained with a sialon composed of 74.4 mole-pct a-Si304 and 25.6 mole-pct ?-A1203. In other tests made with this sialon composition MOR values of 28,120 and 29,500 psi at 25° C, and 23,520 and 16,850 psi at 1,400° C, were obtained when doping with 5 wt-pct ZrSiO4 and ZrO2, respectively.

Jan 1, 1980

By R. K. Clifford

Chalcopyrite (CuFeSz) concentrates produced on the Lead Belt of Missouri typically contain 28 pct Cu and from 0.5 to 1.5 pct each of nickel and cobalt. Most of the nickel and cobalt are present as the mineral siegenite, (Ni,Co)3S4, almost none of which is recovered presently. The Bureau of Mines, U.S. Department of the Interior, has been conducting research on the chalcopyrite to produce a marketable fraction enriched in cobalt and nickel. Ferric chloride leaching of various chalcopyrite (copper) concentrates has yielded residues containing from 10.2 to 16.2 pct Ni and 8.3 to 11.4 pct Co with recoveries of approximately 79 pct. In another approach, laboratory froth-flotation tests have been conducted to investigate the effects of regrinding, roasting, baking, and steaming prior to flotation, with a variety of reagents. The best laboratory results were obtained after regrinding the copper concentrate to 94 pct minus 400 mesh and floating the chalcopyrite at natural pH (6.5) with 0.48 pound of sodium diethyldithiophosphate and 0.01 pound of sodium cyanide per ton of concentrate. This procedure yielded a tailings assaying 20.4 pct Cu, 5.2 pct Ni, and 3.45 pct Co. The tailings contained 67.2 pct of the nickel and cobalt and 15.9 pct of the copper originally in the copper concentrate; the remainder of the values reported to the flotation concentrate, which analyzed 29.6 pct Cu. To verify the laboratory flotation results, a 60 kg/hr process demonstration unit (PDU) was constructed in the Cominco American Magmont mill, Bixby, Mo.

Jan 1, 1978

Researchers with the National Institute for Occupational Safety and Health (NIOSH) have developed a training module to educate both new, inexperienced miners as well as veterans on important issues related to self-rescue and escape procedures. These include: (1) physical and environmental conditions that can be encountered in a mine after a major explosion, (2) knowledge of emergency meeting locations and escape routes, (3) the importance of using self-rescuers, even in seemingly clear air, to keep the lungs isolated from contaminants, and (4) why miners should not go off to look for others who are missing. In addition, the module may stimulate miners to think about and discuss mine explosions and the devastating effects of such an event.

May 1, 2009

By Stephen C. Brown

The major developments of the world's Mineral economy in 1955 were the continued rise in production and consumption of practically all major minerals. the sharp increase in output of the fertilizer minerals in response to demands for greater food output, the cutback, in new investment for steel capacity in Europe and Japan, Europe's continuing decline as a producer of primary minerals, and the emergence of nuclear power as an economically competitive factor in the energy economies of the United States and Western Europe. In resource development, discovery of new natural gas deposits in the North Sea and the continued development of Australia's bauxite and iron ore resources, making this country a major source for these commodities, were significant.

Jan 1, 1967

By Ruth F. Brinkley

This report is the 17th of a series originally issued annually, and more recently bienially, to acquaint the reader with the work of the Division of Explosives Technology, Federal Bureau of Mines. It differs from preceding reports in that its material is presented in two parts: Part I reviews briefly the overall activities of the Division during fiscal years 1955 and 1956;4/ part II presents in abstract form, the publications of the Division during that period. As it is not unusual for research completed in the course of one report period to be published only in the following period, the Bureau believes that the present approach will give a more accurate presentation of its work for the period considered. The Bureau hopes too, that the somewhat more concise presentation will prove convenient to the reader.5/ PART I -RESEARCH AND TECHNOLOGIC ACTIVITIES The activities of the Division during fiscal years 1955 and 1956 reflected the steadily growing preoccupation with factors affecting the safety of permissible explosives and those affecting the tests used for approval of these explosives. Findings by a team of French investigators prompted a study of the influence of atmospheric moisture on the ignition of firedamp by

Jan 1, 1961

By C. M. K. Boldt

This report summarizes five separate Bureau of Mines contract studies on the use of aerial photogrammetry, satellite transmission of in situ instrumentation information, and satellite imagery to monitor and update mine waste embankment data. The equipment used, methods applied, results, recommendations, and cost analyses are presented along with a bibliography of related investigations.

Jan 1, 1987

By F. L. Wideman

Output of ore and waste from metal and nonmetal mines in the United States continued an upward trend and established a new high. The tonnage of ore handled increased 6 percent over that moved in 1964 and the tonnage of waste rose almost 10 percent. Earth moving by these two activities exceeded 3.2 billion tons, an increase of 7 percent over the 1964 total. Crude material from which metal or nonmetal products were derived continued to be about 75 percent of the total material handled. In 1965, surface mining methods were used to produce about 93 percent of the ore, 99 percent of the waste, and 95 percent of the total material handled. These percentages have remained almost constant since the beginning of this decade.

Jan 1, 1966

By W. T. Millar

Graphite in the Suffern deposits near Hillburn, N. Y., consists of flakes ranging in size from fines to one-half inch in diameter. The Bureau of Mines investigated the Suffern deposits in the spring of 1943. Gneiss outcrops were examined, and five trenches excavated and sampled. The graphite is not confined to any definite zone but occurs in small, local pockets. Eleven samples were collected and combined for laboratory tests. Tests by the Bureau of Mines indicate that the graphite ore can be beneficiated by stage crushing, "skin flotation" of coarse flakes, and wet flotation of minus 10-mesh flakes. Over 90, percent of the graphite was recovered.

Jan 1, 1949

By E. D. Gardner

This paper is one of a series on milling methods being published by the United States Bureau of Mines. Atlanta is in Elmore County, Idaho, about 80 miles from the railroad at Mountain Home, Idaho. The concentrator is at an elevation of, 6,000 feet and located in a timbered, well-watered region of relatively heavy snowfall. The snow, however, does not seriously affect local operations. The track road to Mountain Home, which passes over a mountain range, is closed each winter from about November 1 to June 15. During this period concentrates are stored and bullion is shipped by airplane. Power is generated by a Diesel engine and by an auxiliary hydroelectric plant. Gold is the principal metal produced; the or also contains an able quantity of silver.

Jan 1, 1935