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A prototype EM Location System was fabricated and tested at the Geneva Mine near Dragerton, Utah. This system consisted of six manpack transmitters and six manpack receivers covering the frequency band from 900 Hz to 2900 Hz as well as a six channel receiver designed for use in a helicopter. Tests showed that EM signals from lightweight (314 lb) transmitters could be detected both on the surface and from a helicopter through -2 as much as 1650 ft of relatively high conductivity (2 X 10 mhos/m) over- burden. Furthermore, the resulting field strength profiles could be used to determine source location to within 150 ft of the actual surveyed location in the mine. Modifications were made to a Monitoring, Locating and Communications System being tested at the Bruceton Mine, Pittsburgh, Pennsylvania. These modifications have improved the performance and quality of the paging and voice telephony mode of the system. Subsurface receiver modifications have improved reception of voice downlink signals.

Jan 7, 1973

By L. J. Froisland

The Bureau of Mines conducted a 4-year research program at Uravan, Colo., on a 2-1/2-acre reclamation plot on the slope of a uranium tailings pile that had been covered with mine waste rock. The purpose of this study was to determine the effects of plant species, type of irrigation, type of fertilizers, and use of dust control chemicals on plant growth and surface coverage. Best grass coverage, nearly 100 percent with 240 plants per square foot, was developed in a section that was seeded with crested wheatgrass, fertilized with sewage sludge, and sprinkler irrigated. For comparison, a section that had been treated with commercial fertilizers developed 3.1 crested wheatgrass plants per square foot and 24 percent coverage without irrigation, and 8 plants per square foot and 75 percent coverage with irrigation. Results of spraying a dust control chemical were inconclusive. Russian-thistle invaded all test sections and ranged in density from 0.6 to 7.3 plants per square foot.

Jan 1, 1982

By J. S. Hansen

In support of its objective to conserve mineral resources by minimizing premature failure of materials, the Bureau of Mines conducted a cooperative study with the U.S. Department of Energy on the erosion and abrasion resistance of hard materials for valves in coal conversion systems. This report describes a newly developed erosion-testing apparatus and presents data on the erosion resistance of over 200 materials. Erosion resistance of most metals was comparatively low. In contrast, ceramics and cermets such as B4C, WC, SiC, Si3N4, and TiB2, when fabricated to minimize porosity, displayed greater than five times the erosion resistance of metals. Coatings such as boron diffused into Mo and WC, chemical-vapor-deposited TiCN, and electrodeposited TiB2 were highly erosion resistant if applied in thicknesses ranging from 60 to 75 µm. Erosion resistance of cemented carbides was inversely related to metal binder content.

Jan 1, 1979

By L. F. Willmott

The production operation of a Kerpely gas producer at Louisiana, Mo., is described. This unit, originally designed for airblown operation was modified to permit using oxygen in the blast in place of air. The first runs J for test purposes, were made in June 1950. After this, seven production runs were made and these are the subject of this report. Total gasification time was 245 days. In each run, Nut or Pea coke or mixtures of both at a rate varying from 1,700 to 2,300 pounds per hour was converted with oxygen and saturated steam to produce synthesis gas - primarily carbon monoxide and hydrogen -approximating a predetermined rate of 80,000 to 95,000 cu. ft. per hour and a predetermined hydrogen-carbon monoxide ratio, The requirements per 1,000 std. cu. ft. of (CO + H2) were 21.6 to 30 pounds of coke, 213 to 267 std. cu. ft. of oxygen, and 3L4 to 47.B pounds of steam.

Jan 1, 1955

By E. B. Olds

This paper describes the methods and costs of deepening the 3-compartment underground shaft in the Hooper Tunnel adit at the Bunker Hill & Sullivan Mining and Concentrating Company Crescent mine in the Coeur d'Alene mining region, 7 miles east of Kellogg, Shoshone County, Idaho. The work was done with the aid of a Defense Minerals Exploration Administration contract (No. Idm-E493, Docket No. DMEA-2764). Preparation for deepening the shaft was begun March 26, 1953, and sinking was completed May 27, 1954. The shaft, bottomed at 1,275.5 feet in 1939, was deepened to 3,276 feet, using mechanical mucking and intermediate pockets. A total of 50,349 man-hours was required to complete the work of sinking 2,000.5 feet, cutting 7 pump stations, and driving 2 pocket raises. The rate of advance was 7.1 feet of shaft per operating day, or 8.4 feet per day of actual sinking. The total direct cost for sinking was $205.20 per foot.

Jan 1, 1957

By Donald P. Mickelsen

The raining and quarrying trends data shown in this report were reported to the U.S. Bureau of Mines (USBM) by mining and quarrying companies on the Mine Information Supplement survey, as well as by mineral producers on 58 annual USBM production and consumption surveys covering 59 nonfuel mineral commodities. The 1993 data presented in the tables of this chapter, were processed for the first time using the USBM Automated Mineral Information System. Domestic mining of nonfuel mineral materials totaled 3.7 billion metric tons in 1993, including 2.2 billion tons of crude ore nun& or quarried and 1.5 billion tons of mine waste and ore from development. This \vas an overall increase of 11% over that of 1992. These data do not include construction sand and gravel which until 1993 has been surveyed biennially. Starting in 1994, construction sand and gravel and the stones, which were also surveyed biennially, will be surveyed annually.

Jan 1, 1993

By Alla D. Mah

Relatively pure aluminum nitride (AIN) recently has been prepared in sufficiently large amounts to permit a variety of experimental studies.4/ Several mechanical and chemical properties have been investigated, which show that this substance has good potentialities as a container for liquid aluminum, gallium, and boric oxide. The present work by the Bureau of Mines was undertaken to obtain thermo-dynamic data pertinent to the calculations regarding thermal stability and reactivity of aluminum nitride. The following measurements were made: (1) determination of the heat of formation from the elements at 298.15° K.; (2) determinations of the heat capacity over the temperature range 51° to 298.15° K. and the evaluation of the entropy at 298.15° K. therefrom; and (3) determinations of the heat content over the temperature range 298.15° to 1,800° K. These data are combined to obtain free energies of formation from the elements between 298.15° and 2,000° K.

Jan 1, 1961

By Allan F. Smith

The Bureau of Mines studied toxic products produced by burning eight fire-resistant mines conveyor belts, a brattice cloth, and an electrical cable insulation obtained from laboratory-scale burning experiments under various air-flow conditions. Generally, CO product concentrations for most materials were noticeably higher then the NO2 and HC1 levels that were measured; also, no phosgene was detected. However, several of the fire-resistant belt samples yielded HC1 concentrations that were above the reported lethal level for 1/2 to 1-hour exposures, although these data were limited to flow conditions where air dilution effects were small; the belt materials that showed this behavior included samples of polyvinyl chloride, styrene butadiene, styrene butadiene blends, and a British neoprene which yielded the greatest amount of toxic vapor. In addition, some results are presented on the phosphoric acid concentrations that may be produced from the decomposition of ammonium dihydrogen phosphate when dispersed on a burning coalbed.

Jan 1, 1973

By Robert J. Timko

The objective of this Bureau of Mines research work was (1) to determine how well the E. I. Du Pont de Nemours and Company P-2500 personal dust sampling pump controls the flow rate at 2 L/min and (2) to compare respirable dust mea-surements made using the P-2500 with those made using a nonpulsating sampling flow system, both using the Dorr-Oliver 10-mm nylon cyclone dust size classifier. The calibrator and the operation manual for the P-2500, supplied by the manufacturer, were also evaluated. Flow tests consisted of long-term (6-to 8-hour) flow stability tests at various backpressures, a low-flow indicator examination, flow controller response time tests and pulsation tests. Dust tests were performed using coal, silica, and Arizona road dust. No tests were performed to examine effects of temperature, barometric pressure, vibration, or mechanical shock. These pumps performed well within manufacturer specifications in all tests.

Jan 1, 1982

By L. B. Pankratz

Enthalpies above 298° K were determined for AgCl to 1,400° K and for AgBr to 1,200° K by copper-block calorimetry. Before melting, both compounds showed an anomalous increase in enthalpy, an effect associated with lattice defect formation. Melting points and heats of fusion were determined to be AgCl, 730° K and 2,945 cal/mole; AgBr, 700° K and 2,030 cal/mole. The heat capacity of both melted substances decreased with increasing temperature over the entire liquid ranges investigated. Enthalpies above 298° K were tabulated at even temperatures along with derived entropy increments and heat capacity values. The results were combined with the known heats of formation and entropies at 29.8.15° K to obtain values of the heats and free energies of formation over the range 298.15° to 1,400° K for AgC1 and 298.15° to 1,200° K for AgBr.

Jan 1, 1970

By W. R. McDonald

The Bureau of Mines, U.S. Department of the Interior, conducted small-scale field tests on acidic copper tailings as part of its effort to develop, improve, and demonstrate technology for stabilizing mining and mineral-processing wastes. Two successful demonstration revegetation plots were established on an abandoned copper-tailings pond located on public land adjacent to Holden Village, Wash. The tailings were neutralized with treatments of either dolomitic lime or limerock and fertilized with processed sewage sludge and/or commercial fertilizer. Excellent plant growths covering 70 and 24 percent of the surface were achieved on 1/8-and 1-1/2-acre test plots planted in 1973 and 1974, respectively. Regar brame, Tegmar intermediate wheatgrass, and tall wheatgrass provided the best plant growth and surface coverage. The target pH of tailings neutralization was 6.8; however, good plant growth occurred in areas where the soil pH ranged from 2.9 to 5.8.

Jan 1, 1978

By William H. Tavenner

1. The 1952 Annual Report of the West Virginia Department of Mines lists nine beds that arc being mined in Logan County, of which the Cedar Grove and Chilton are the most important. The Cedar Grove group, No. 2 Gas, and Alma beds have the largest remaining reserves, in the order given. 2. Known measured and indicated reserves in all beds, based on a minimum thickness of 14 inches and 1,800 short tons per acre-foot of coal in place, are estimated at 5,411 million tons as of January 1, 1954. Of this total, 3,939 million tons is in beds 28 inches and more thick. Areas in each bed were omitted from the estimate because available data relative to the bed characteristics were too meager for making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimate reserves.

Jan 1, 1956

By Hal H. Engel

This publication was written in response to numerous requests for information about the Federal Bureau of Mines' "Demonstrated Lecture on Flame Propagation and Permissible and Explosion-Proof Electrical Equipment." The requests came principally from: (1) Persons wanting to know more about the demonstration before requesting it for groups they represented; (2) persons wishing advance information to help publicize a meeting where the demonstration was to be given; and (3) members of audiences desiring something to help them remember the salient points, facts, and figures presented during the lecture and demonstration. The purpose of the demonstration that accompanies the lecture is to show: (1) Variations in flame speed and pressure at various percentages of flammable gas within the flammable range; (2) effect of flame speed on the "pressure piling" within the area confining the mixture; and (3) the application of flame speed and pressure piling to the combustion of surrounding gas and to the design and maintenance of electrical equipment used in hazardous locations.

Jan 1, 1960

By J. M. Provost

1. Estimates have been made for eight coal beds in Marion County, but only the Pittsburgh is important from a production standpoint at this time. The Pittsburgh bed has the largest recoverable reserve, and the Sewickley is second in importance. 2. Known measured and indicated reserves thickness of 14 inches and on 1,800 short tons estimated at 3,141 million tons, as of January lion tons is in beds 28 inches and more thick in all beds, based on a minimum per acre-foot of coal in place, are 1, 1955. Of this total, 2,983 mil-Areas in each bed were omitted from the estimate because available data relative to the bed characteristics were too meager for making an estimate that conforms with the definitions of measured and indicated coal adopted for this study. Should future drilling or development prove reserves in these areas, such reserves should be added to the total estimated reserves.

Jan 1, 1956

By Robinson Newcomb

Gypsum is a form of hydrated calcium sulfate (CaS04.2H20) which is widely distributed over the earth's surface. The two varieties worked commercially are rock gypsum and incite. Rock gypsum, the variety commonly mined for commercial purposes, is a relatively soft mineral having a specific gravity of about 2.3 and weighing about 150 pounds per cubic foot. The chief producing States are New York, Michigan, and Iowa. Before being used the crude gypsum is ground and generally calcined. The predominant use of gypsum is for building purposes (the manufacture of plaster), for which calcined gypsum is required. Gypsum is also used as a retarder in Portland cement, as fertilizer, and for other purposes. GYPSUM MINING Crude gypsum is mined by two methods - underground and open-pit. Although the use of the former method predominates, open-pit mining increased in relative importance during the early twenties and contributed about two-fifths of the output during the period 1925-38.

Jan 1, 1940

By E. L. Litchfield

Four short-term studies of practical ignition problems were undertaken and completed during the course of the Bureau of Mines project "Development of Specifications for Intrinsically Safe Equipment." Conclusions were as follows: (1) the most easily ignitible mixture of propane-air in a PTB break flash apparatus is approximately 5.2 percent propane; (2) miniature lamp bulbs to be used in intrinsically safe circuits are about as incendive to coal dust-air as to methane-air and should be tested in gas mixtures containing about 7.0 to 7.5 percent methane; (3) the sodium amalgam contained in high-pressure sodium lamps does not present an ignition hazard for coal dust or methane, where the lamps contain no more than 30 milligrams of amal-gam; (4) the maximum allowable surface temperature of permissible electrical enclosures should remain at 150° C despite efforts by industry groups to raise the value to 200° C.

Jan 1, 1980

By P. Comba

The U.S. Bureau of Mines investigated a hydrochloric (HC1)-calcium fluoride (CaF2) leaching procedure to treat domestic manganese (Mn)-bearing silicate resources. The proposed process is an alternative to high-temperature and energy-intensive extractive techniques. Single-stage leaching with a stoichiometric amount of HCl and a F-Mn mole ratio of 0.2 extracted 96 pct of the Mn when the leach conditions were 50° C, 3 h, and 35 pct solids. Ninety-eight percent of the Mn was extracted during countercurrent leaching at similar conditions. A process flowsheet was developed that incorporated HC1-Cab leaching, excess leach acid utilization, fluoride (F) recycle, and Mn recovery. When the domestic manganese silicate ore was processed, 98 pct of the Mn was extracted, 99 pct of the Cab was reclaimed, and a leach residue was produced that passed the Environmental Protection Agency (EPA) Extraction Procedure (EP) Test for nonhazardous waste.

Jan 1, 2010

By Bryan F. Ulrich

If resin-grouted roof bolts are not installed correctly, mine roof reinforcement can be affected, and roof falls can result. A bolt installation variable that is readily controlled by the mine operator is annulus thickness. The objective of this U. S. Bureau of Mines investigation was to study the effect of annulus thickness variations on the integrity of 3/4-in-diam resin-grouted bolts. Forged-head test bolts, 2 and 1 ft long, were installed in concrete blocks that had been drilled with 1-, 1-1/8-, 1-1/4-, 1-3/8-, and 1-1/2-in-diam bits. Standard pull tests were performed; then the concrete was broken away from the bolts so that grout mix quality could be inspected. It was found that the optimum annulus thickness is 1/8-in (l-in-diam drill hole), and as annulus thickness increases from the optimum, there is a corresponding decrease in grout mix quality, effective grout ratio, and axial stiffness.

Jan 1, 1989

Occupational illnesses are more difficult to identify than on-the-job injuries. Many illnesses related to occupational exposures may not be diagnosed until years after exposure; by that time, exposed workers may have changed jobs or left the workforce. Other approaches to identifying occupationally related illness are analysis of death certificate data (see chapter 2) and medical examination studies of workers known to have high exposures to hazardous agents. Figures 5-1, 5-3, 5-4, 5-6, 5-8, and 5-10 show, for each commodity, the percent of illness conditions reported to MSHA by nature of condition. Heart attacks that occurred on the job are reported without regard to work-relatedness. Figures 5-2, 5-5, 5-7, 5-9, and 5-11 show rates by year during 1986-1995 for selected conditions. Since there are many limitations on the accuracy of illness reporting, the frequencies and rates shown here should not be considered directly comparable across commodities. Figure 5-12 shows estimates for hearing loss by age among coal miners compared to a nonoccupationally noise-exposed population. These data come from a study by Franks [1996] of a group of audiograms obtained on coal miners by a commercial company. Using the NIOSH definition of hearing impairment, i.e., an average hearing threshold level for both ears that exceeds 25 dB at frequencies of 1,000, 2,000, 3,000 and 4,000 Hz, the figure shows that by age 30, more than 10% of miners suffer hearing impairment; by age 50, 90% of miners have hearing impairment. In contrast, only 10% of the nonoccupationally noise-exposed population suffer hearing impairment at age 51, and 50% of the nonoccupationally exposed population have hearing impairment at age 69. Figure 5-13 shows a similar analysis of commercial audiograms on male metal/nonmetal miners [Franks 1997]. At age 20, approximately 2% have hearing impairment using the NIOSH definition of hearing impairment described above. This increases to 7% at age 30, 25% at age 40, and 49% at age 50. In contrast, only 9% of the nonoccupationally noise-exposed comparison population have hearing impairment at age 50. Franks' analysis showed a different pattern for female metal/nonmetal miners; they developed hearing loss at the same rate as would be expected for a non-noise-exposed female population.

Jan 5, 2000

By R. D. Wilson

Ten to twelve million tons of dust is produced by cement kilns annu-ally in the United States, resulting in a serious waste disposal problem. The Bureau of Mines investigated two alkali volatilization methods for converting this dust into materials for making portland cement and a useful potassium product. Portland cement kiln dust was found to be composed of finely ground cement raw materials (CaC03 and 8i02) having a layer of alkali sulfate (K2S04 and Na2S04). In this form, it cannot be directly recycled to cement kilns because concrete is weakened by a reaction between the alkali and the aggregate. Portland cements with 28-day strengths above 5,000 psi were produced from low-alkali residues using sintering and melting methods. For nearly complete removal of alkalies, primarily potassium sulfate, from cement kiln dust, a temperature above 1,300° C and a reducing atmosphere were required.

Jan 1, 1986