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Prevention of coal-mine explosions depends largely upon thorough knowledge of the causes that initiate explosions. A review of coal-mine explosions in one geographical area when supplemented by nationwide data of similar nature, should serve as a guide for the adoption of measures for explosion prevention. Explosions in bituminous-coal mines of the United States during the 10 years ended December 31, 1932, ranked third in the causes of fatal accidents and constituted 16.1 percent of all fatal accidents in bituminous mines. Kentucky now ranks fourth in coal output in the coal-producing States of this country; a study of the coal-mine explosions in this state will be of definite interest locally among coal-mining people, as well as to those in the coal-mining industry who are concerned in preventing coal-mine explosions. This circular reviews gas and dust explosions in Kentucky coal mines to show their hazards, to point out the influence of certain factors in causing explosions, and to indicate the effectiveness of preventive measures.

Jan 1, 1934

By Wesley A. Grosh

The Vest nickel prospect, in Floyd County, Va., was discovered about 25 years ago. Limited exploration of the deposit had indicated some appreciable nickel mineralization in the sulfide ore. The property was examined on March 9, 1943, by an engineer of the Bureau of Mines in company with C. W. Vest, owner of the property. A limited exploration program was recommended. Two holes totaling 320 feet were diamond-drilled in January 1944. Drilling indicated the sulfides are sparsely disseminated. The only nickel values of interest were at the old prospect shaft.

Jan 1, 1949

An independent contractor is defined by the Mine Safety and Health Administration (MSHA) as ?any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine.? Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines.

Aug 1, 2009

An independent contractor is defined by the Mine Safety and Health Administration (MSHA) as ?any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine.? Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines. Companies In 2007, a total of 2,999 contracting companies reported employment at coal mines to MSHA, or 35.7% of all independent contracting companies.

Aug 1, 2009

By Peter N. Gabby

A mineral purvey of 40,000 acres of the 42,213-acre Little Humboldt River Wilderness Study Area was conducted by the U.S. Bureau of Mines in 1985 at the request of the U.S. Bureau of Land Management. There are no identified mineral resources but anomalous gold, silver, mercury, and arsenic concentrations were found. The study area is located in Elko County, NV, in the Owyhee Upland geomorphic subprovince. It is underlain by mid- to late-Miocene-age rhyolite, basalt, tuff, vitric ash, and tuffaceous siltstone. On the south side and partly within the study area, a mining company recently (January 1986) located 125 contiguous claims over an area of hydrothermally-altered volcanic rocks that have anomalous surface concentrations of gold, mercury, arsenic, and silver. Anomalous gold-silver concentrations in altered rocks were encountered at several other widely scattered localities in the study area. These elevated metal concentrations and associated hydrothermal alteration indicate gold resources may be present in the study area. A 20-ft-thick bed of diatomaceous earth, which contains 60 to 85 percent diatoms, crops out 0.3 mi north of the study area. Elsewhere, three samples of altered volcanic tuff taken within the study area contain from 46 to 70 percent zeolite (clinoptilolite). The diatomaceous earth and zeolite sampled are not of sufficient quality to compete with materials presently being marketed. There has been no mineral production from the study area, but a caved adit, about 25 ft long, and six prospect pits were found.

Jan 1, 1987

By Harry D. Jumper

This paper describing the methods of ruining a sand, gravel, and bowlder deposit 20 miles east of Los Angeles, and the classification and preparation of these materials for market, is one of a series being prepared for and published by the United States Bureau of Mines on methods and cost of mining sand and gravel. These papers are designed to disseminate technical information regarding, the methods used. The cost tabulations represent operating expenditures only and not total costs. It is recognized that publication of total costs might in many instances cause embarrassment to individual operators as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion anti study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations stall ensue. The description contained herein is typical of this industry in Southern California. ACKNOWLEDGMENT The author acknowledges tine assistance of L. L. Rogers, vice-president and manager of production and distribution for the Consolidated Rock Products Co., in the preparation of this paper.

Jan 1, 1933

By Wilbur A. Haley

The demand on the nation's reserves of high-quality coals suitable for metallurgical purposes is resulting in the rapid depletion of some of the thicker coal beds. These beds are thick enough to permit the use of modern mechanized mining equipment. Many of the thin beds are not being mined at present. In limited areas where the coal is less than 36 inches thick some beds are mined by various conveyor methods. Usually, the room-and-pillar system or some modification of it is used, and often no attempt is made to extract pillars. Consequently, an appreciable quantity of a valuable resource is lost. Many steel companies and coal operators consider reserves of low-and medium-volatile coking coals to be critical, especially in areas where the thin beds are not being mined by modern mining methods. To improve recovery and to promote more-extensive mining in thin beds, methods and devices that are new to American coal mining but applicable to the mining of thin coal beds should be tried. As one of the functions of the Bituminous Coal Mining Section of the Bureau of Mines is to promote improved mining practices and efficiency in the interest of conservation, research in that line is necessary. In 1945 coal planers were observed in operation in Germany by a Bureau engineer member of Solid Fuels Mission to Germany. Planer designs and history of early developments and operations were published. In 1949 an improved planer was again studied by Bureau engineers, and its adaptability to certain conditions in the United States, especially thin beds of friable coal, was considered practicable. After the war the planer was improved, in design and for several years has been operating successfully in the Ruhr. Because of the conviction that the device would be successful, both from the standpoint of conservation and operational prodl1ctivity, under certain conditions in the United States, the Bureau of Mines, through the Bituminous Coal Mining Section, entered into a cooperative agreement with the Coal Division of Eastern Gas & Fuel Associates and Mining Progress, Inc. The purpose of the agreement was to conduct an experiment in modified longwall mining, using a new-type German-built coal plow or planer, known as the Loebbe Habel, supplied by Mining Progress, Inc. The experiment was made to determine if this type of mining equipment operated on a longwall face could be adapted to some of the thinner American coal beds. Such an experiment also would afford many opportunities to study the possibilities and principles of this type of equipment as well as the many factors involved in the mechanical mining of a longwall face.

Jan 1, 1952

By Lloyd A. Morley, Alan M. Christman

Mine One General. The first summer field trip for the purpose of collecting data on open-pit metal mine grounding systems was marred by the fact that the group's ground test instrument was damaged in transit and proved to be inoperative. Fortunately, the mine personnel had a similar instrument which was then used for all tests. System Description. Power is purchased from the utility at either 69 or 100 kV. This is transformed to 4160 V at the pit substations and distributed around the periphery of the pit via a "ring bus." The three phase wires and the safety-ground conductor are carried on a conventional wooden pole and cross-arm support structure. At key loca¬tions, overhead feeders carry power from the ring bus down over the benches and into the pit. Each overhead feeder is terminated at a switchhouse, from which an SHD-GC trailing cable supplies power to the electric loading shovels. Each pit substation has a main or system-ground mat, installed by the utility, and a separate safety-ground mat, which is constructed by mine personnel. Three of the safety-ground mats are quite old, and personnel at the mine could not recall what type of construction was used. However, records are available on the fourth mat and construc¬tion details are shown in Figure 64. Protective circuitry includes a donut or window-type current transformer through which the three phase wires are run. Additional

Jan 1, 1976

By R. Craig Smith

The Bureau of Mines conducted a study of production costs for the secondary lead industry and determined costs for present, pending, and proposed environmental legislation. Operating costs for smelters by capacity groups range from 16.8 to 19.6 ¢!lb of refined lead. Present regulatory compliance costs for these groups range from 2.2 to 2.4 ¢!lb. Pending compliance costs could add 3.5 ¢!lb of refined lead, and proposed regulations could add another 1.3 ¢!lb. The individual capital costs necessary to comply with pending environmental regulations are estimated to be $1.8 million for small smelters and $10.4 million for large smelters. Proposed regulations could require additional expenditures from $1.9 million for small smelters to $4.9 million for large smelters. These cost estimates, based on average 1985 dollars, indicate that pending and proposed legislation could add significantly to capital and operating costs of the secondary lead industry. These regulatory compliance costs may result in a loss of up to 40 pet of secondary lead production capacity.

Jan 1, 1987

By F. W. Benn

The Bureau of Mines investigated flotation methods for recovering fluorite and byproducts from two samples of the Fish Creek deposit in Eureka County, NV. The preferred method for tre.ating a fluorite-beryllium sample included (1) fluorite rougher and cleaner flotation, (2) desliming at 20 um, (3) muscovite flotation, (4) silicate flotation, (5) sodium hypochlorite wash of silicate concentrate, and (6) beryllium rougher and cleaner flotation from the silicate concen-trate. Laboratory results showed that over 94 pct of the fluorite was recovered in a recleaner concentrate containing 98 pct CaF2, Beryllium flotation produced concentrates containing in excess of 5 pct BeO with recoveries over 70 pet. The preferred method used for a fluorite-mica sample consisted of (1) fluorite rougher and cleaner flotation, (2) desliming at 20 um, and (3) mica flotation using an anionic-cationic collector system. Laboratory results showed that 84 pct of the fluorite was recovered in a recleaner concentrate containing 96 pct CaF2, Mica flotation produced a concentrate containing 95 pct mica at 85-pct recovery.

Jan 1, 1986

By Larry G. Stolarczyk

This report deals with information regarding a new Medium Frequency (MF) Wireless Communication System for underground mines. This new telecommunication system works on low loss electromagnetic wave propagation modes which allow it to provide quality radio communications almost anywhere in a mine. Tests show the MF system can provide improved safety and managerial control, increased productivity, better organizational team-work and reduced maintenance cost; furthermore, MF's unique design allows for easy installation at a minimum cost. This paper covers the following: 1) MF design plan, 2) Overview of mine radio communications systems, 3) Preparations needed for designing an MF system, 4) MF equipment, 5) MF installation, 6) MF design considerations, 7) MF design specifica¬tions, and 8) Recommendations dealing with MF system. Experiments in four mines are illustrated to demonstrate the success and via¬bility of the MF system. The mines range from small (500 tons/day) to large (67,000 tons/day) capacity and represent several different mining methods. The MF Wireless Communication System represents an advancement in mining communication and the groundwork for other advanced mine systems.

Jan 9, 1984

By Peter J. Clarke

Development of the mineral and energy resources of Afghanistan appeared to be a top priority of the Soviet-controlled Government in the country. In the Afghan Government's plan for 1980-81, the largest allocation in the development budget was for mines, industry, and energy (46.7%). In contrast, only 23.1% of the budget was allocated for agricultural development, despite the fact that the great majority of the population was dependent on farming. The mineral industry of Afghanistan consisted of the production of natural gas, cement, coal, fertilizer materials, and rock salt. Production levels for all of these commodities were down an average of 45% from those of 1978, before the Soviet invasion. Prior to the invasion, small quantities of asbestos, barite, and talc had been produced along with about 6,000 to 7,000 kilograms per year of lapis lazuli, a semiprecious gem stone. Afghanistan had supplied about 80% of the world's output of lapis lazuli. Following direct Soviet intervention, production of these minerals declined to near zero.

Jan 1, 1983

By T. O. Llewellyn

The Bureau of Mines, as part of its goal to develop technology that can conserve domestic mineral resources investigated beneficiation methods for recovering phosphate minerals from two Southern Florida deposits with high magnesium content. Chemical analyses of sized fractions indicated that no coarse pebble concentrate could be produced from either deposit. Conventional fatty acid-fuel oil batch flotation tests on two phosphate samples, analyzing 6.8 and 8.5 pct P205, yielded concentrates containing 28.97 to 29.80 pct P20S at recoveries ranging from 72.4 to 76.9 pct of the flotation feed. The MgO content ranged from 1.20 to 1.36 pct. Bubbling S02 gas through an aqueous concentrate slurry, further reduced the MgO content of these phosphate concentrates to 0.5 and 0.8 pct, but with a concomitant loss in the phosphate recovery. Settling characteristics of slimes from both phosphate samples showed a slow settling rate, which is a typical characteristic of other slimes in the region.

Jan 1, 1981

By F. R. Cattoir, D. H. Baker

Fused - salt electrorefining has been successfully applied to the purification of vanadium metal . The electrolyte used in this refining technique was sodium chloride to which had been added 3 to 6 percent vanadium as vanadium dichloride . The average deposition current efficiency was 91 percent . Oxygen and nitrogen , the impurities in commercially produced vanadium metal , were reduced by two - thirds of the amount contained in the feed material . Hardness of the vanadium- metal product was reduced from an initial 97 Rockwell B ( RB ) to a minimum of 35 Rg . The reduction of these impurities markedly improved the plasticity of the final product obtained by melting the crystalline cell metal into small ingots . These ingots could be given a 99 - percent cold reduction by rolling before edge cracking appeared . Growing interest in high - purity vanadium and the industrial need for purer metals and improved alloys for use under high temperatures and high speeds have demanded the elimination and/or control of impurities . Accordingly, research to eliminate or control the undesirable impurities has been expanded .

Jul 1, 1960

By Donald R. Irving

ALTHOUGH the quantity of material handled at metal and nonmetal mines in the United States in 1962 was 2.7 billion tons, the same as in 1961, a larger proportion was waste. At metal mines, crude ore production declined 1 million tons and waste output rose more than 18 million tons; at nonmetal mines crude ore production declined 6 million tons and waste output rose 36 million tons. Copper and iron ore producers increased their share of crude ore and material handled from about three-fourths to four-fifths of the national metals total, and sand and gravel and stone producers in-creased their share of the nonmetals total, also from three-fourths to four-fifths. Six States-Arizona, California, Florida, Michigan, Minnesota, and Utah-each handled more than 100 million tons of ore and waste, and together they accounted for 43 percent of the U.S. total. When the large-volume construction materials (sand and gravel and stone) were excluded from the totals, four States-Arizona, Florida, Minnesota, and Utah-supplied over half of the material handled.

Jan 1, 1963

By R. L. Grant

At the Eighth International Conference of the Directors of Safety in Mines Research, Sartorius and Thouzea5/ presented and discussed data obtained in explosives tests made under varying conditions of humidity. These tests showed that there was less probability of explosives failure when the humidity of the testing gallery atmosphere was high. As it is to be expected that the relative humidity of mine atmospheres where permissible explosives are used will not be identical with that of the test-gallery atmospheres, the influence of atmospheric moisture upon the incendivity of permissible explosives is of the utmost importance if decreasing humidity reduces the relative safety of an explosive. Because of this and because the question has recurred frequently in discussions of gallery testing at Bruceton, Pa., it was decided to investigate the effect of humidity and ambient temperature on the ignition of firedamp by explosives, applying the small-scale gallery methods developed at the Bureau of Mines and used earlier to study the fundamental causes of such ignitions.6 7 8/

Jan 1, 1956

By B. J. Scheiner

The Bureau of Mines investigated an electrolytic technique for oxidizing ore slurried with brine to determine its effectiveness in extracting mercury from ores. Optimization experiments conducted on a 2.5-pound-mercury-per-ton ore resulted in 95 percent mercury extraction with operating conditions of 30° C, a current density of 0.5 ampere per square inch, and a treatment time of 3.5 hours. Corresponding power consumption amounted to 38 kilowatt-hours per ton of ore treated. Amenability experiments conducted on 62 different mercury ores resulted in 90 to 99 percent mercury dissolution from ores containing 0.6 to 20 pounds of mercury per ton of ore, Treatment time ranged from 1 to 7 hours in 4-to 20-percent sodium chloride solutions, and power consumption was in the range of 10 to 50 kilowatt-hours per ton of ore. Pilot mill experiments in a 100-to 200-pound-per-hour extraction plant have been in progress to quantify power and reagent requirements. These data will be reported in a subsequent publication.

Jan 1, 1973

By A. F. Colombo

Infrared spectroscopy employing attenuated total reflectance (ATR) techniques on thin films of dried gelatinized starch solution was used during Bureau of Mines research to determine the structural and impurity differences in starch products and to correlate these characteristics with the flotation response of a nonmagnetic taconite. All of the starch products evaluated gave spectrograms which were characteristic of the anhydroglucose monomer and its polymerization product. Distinct infrared absorption peaks caused by the protein molecule were observed and were used to classify the starches. Correlation of laboratory flotation of calcium-activated gangue from a Mesabi Range nonmagnetic taconite and infrared spectra produced from gelatinized starches showed that protein impurities and linear chain structure limited the effectiveness of starches as iron mineral depressants. Starch products having spectrograms similar to pure amylopectin were generally good depressants for iron oxides, were effective at about one-half the addition that was required for starches that gave infrared responses similar to pure amylose, and yielded acceptable iron concentrates containing 61.5 percent iron and 6.5 percent silica.

Jan 1, 1969

By Charles P. Lazzara, Charles D. Litton, Frank J. Perzak

This U.S. Bureau of Mines report details the results of a series of large-scale experiments where small coal fires were used to ignite the conveyor belt at air velocities ranging from 0.76 to 6.1 m/s. In the tests, electrical strip heaters imbedded within a pile of coal were used to heat the coal to a point of flaming ignition. The flaming coal subsequently ignited the conveyor belt located approximately 5 to 10 cm above the coal pile. During the tests, temperature, CO, and smoke levels were continuously measured in order to determine both alarm time and level as the fire intensity progressed through the stages of smoldering coal, flaming coal, and flaming coal plus flaming belt. Analysis of the data leads to certain conditions of air velocity and sensor alarm levels that are required for early detection of conveyor belt entry fires. Two nomographs are presented, which define sensor alarm levels and sensor spacings as a function of belt entry cross-sectional area and belt entry air velocity.

Jan 1, 1991

By J. S. Browning

The Bureau of Mines investigated the concentration characteristics of high-clay sylvinite ores from potash companies operating in the Permian basin near Carlsbad, N. Mex. These ores, containing 14 to 19 percent K20 and 3 to 5 percent clay slimes, cannot be effectively processed by current commercial flotation methods because of their high clay content. A solution to this problem was shown to be the use of two-stage moderate scrubbing conditions for clay disaggregation and removal as opposed to strenuous attritioning. Bench-scale beneficiation techniques for recovering potash minerals by flotation from the scrubbed material resulted in acceptable product grades and recoveries. By using a coarse grind, emphasis was placed on production of premium granular and coarse products. Flotation results showed that concentrates of 59.6 to 60.4 percent K.0 values can be obtained. Continuous pilot plant beneficiation techniques for recovering potash minerals by flotation resulted in concentrates containing 58.8 to 59.8 percent K20 with recoveries of 69.7 to 81.4 percent of the K20.

Jan 1, 1975