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By K. D. Luxbacher

Understanding methane emissions in underground coal mines is critical for a safe and productive mine. In addition to reasonable estimation of initial coalbed reservoir parameters, it is also crucial that changes in effective stress due to mining and pore pressure reduction are taken into account due to their effects on porosity and permeability. Primary parameters for estimation of emissions or modeling of the mining environment for this purpose are porosity and permeability which can change dramatically as a result of stress redistribution associated with mining and gas desorption from a large coal volume. These parameters affect the emission rates and ventilation requirements, as well as water inflow into the working environment. Stopping leakage, on the other hand, is a secondary stress dependent factor in estimation of emissions, as convergence of the roof and floor strata, compromising the integrity of the stopping, may result in leakage, making prediction of ventilation requirements difficult. This paper aims to examine the effects of porosity and permeability changes of the coal seam on methane emissions in an underground continuous miner section. The models were developed and executed in a dynamic fashion to simulate an advancing section. Through this process, the changes of effective stress in coal, particularly their change paths, on porosity and permeability were incorporated into the models and methane emissions, concentrations, air requirements, water inflow and possible leakage from the stoppings were investigated using a conventional coalbed methane reservoir model.

Jan 1, 2009

By Thomas M. Barczak

he stiffness characteristics of longwall shields were investigated in this Bureau of Mines study. Since longwall strata activity is characterized by roof-to-floor and face-to-waste displacements, a model with two degrees of freedom was used to describe the load-displacement relationship of the shield structure. The model considers the support as an elastic body and relates horizontal and vertical resultant forces acting on the support to associated displacements as a function of the stiffness of the support structure. Stiffness coefficients under full canopy and base contact configurations were determined by controlled displacement loading of longwall shields in the Bureau's Mine Roof Simulator (MRS). Three two-legged longwall shields of different manufacture were investigated. The stiffness characteristics of these shields were evaluated relative to two parameters, namely, shield height and setting pressure. The test results indicate a reduction in shield stiffness for increasing height. Setting pressure was found to have less of an effect on shield stiffness, producing only a slight increase in stiffness as setting pressure increased. Similar trends were observed for all three shields, indicating a similarity in stiffness characteristics for shields of the same basic configuration.

Jan 1, 1988

By Jack L. Henry

The Bureau of Mines conducted seven pioneering experiments in a 12-inch-diameter Kroll reduction reactor to examine the feasibility of coreducing the chlorides of Ti, AI, and V to produce a homogeneous titanium alloy sponge. The coreduction studies proceeded in a normal manner, and the yields of sponge were comparable with those of pure titanium sponge made in the same reactor. Vanadium concentration was very uniform throughout the sponge cake when VC14 in solution in TiCl4 was fed into the molten magnesium. More difficulty was encountered in feeding solid VCl2 and AIC13. Vanadium and aluminum concentration in the sponge was not uniform, and mechanical difficulties were experienced with the small-scale screw feeder. Although the sponge varied in composition from region to region, the ingots prepared from it were uniform in composition.

Jan 1, 1974

By C. C. Clark, R. R. Backer, J. D. Vickery

This report presents the results of tests conducted by the U.S. Bureau of Mines to determine the transport characteristics of highly concentrated paste backfill mixes made from dewatered total mine tailings. The slurry concentrations of the mixes were all above 78 pct by weight with slumps ranging from 6.4 to 16.5 cm (2.5 to 6.5in). Laboratory material property tests and full-scale pumping tests were conducted using pipe diameters of 102,128, and 154 mm (4, 5, and 6 in) and a positive-displacement pump. The results indicated that the tested backfill mixes can be successfully transported as a stiff paste and identified the influence of and the interaction among the various mix and system variables.

Jan 1, 1995

Antitrust Investigation Dropped. - The Department of Justice announced that it was dropping its 5-year investigation of the aluminum industry. The investigation was over whether the aluminum companies were acting as if they were a shared monopoly. Deep Seabed Mining. - The Department of Commerce's National Oceanic and Atmospheric Administration (NOAA) has established an Office of Ocean Minerals and Energy which will be responsible for implementing the Deep Seabed Nard Minerals and Energy Act and the Ocean Thermal Energy Conversion Act. It will establish licensing and regulatory programs.

Jan 1, 1980

By R. W. Geehan

The Bureau of Mines has been investigating deposits of critical and essential minerals in the United States since 1939. Bureau engineers made a preliminary examination of the Morefield mine early in 1943 and recommended investigation by trenching and diamond drilling, The Bureau of Mines conducted work from August to December of 1943, which indicated that the Morefield mine was a favorable location for an experimental mining program. The Bureau of Mines carried on such a program from September 1947 to March 1949. The property investigated is 30 miles southwest of Richmond in Amelia County, Va. (fig. 1). During World War II mica and beryl were shipped from the Morefield mine, but after the high prices and premiums paid during the war years were not available the mine was closed.

Jan 1, 1953

By W. P. Yant

A previous report of the Bureau of Mines dealt with the toxicity of dichlorodifluoromethane, a new refrigerant that has a remarkably low toxicity. Continued research by the Frigidaire Corporation and toxicological experiments performed in the Laboratory of Applied Physiology of the University of Cincinnati revealed another organic fluoride, dichlorotetrafluoroethane, whose toxicity also appeared to be of a very low order and whose physical and chemical properties make it suitable for refrigeration purposes. In addition to low toxicity, safety in its use is further enhanced by its physical properties, which permit the design of equipment that operates at comparatively low pressures and hence mitigates the dangers and problems of leakage. The investigation described in this report was performed by the Bureau of Mines at the request and with the cooperation of the Frigidaire Corporation.

Jan 1, 1932

By Wm. W. Odell

This report comprises a brief outline of the experimental cracking of natural gas in a water-gas generator at Louisville, Kentucky, and a discussion of the results obtained. The work was done under a cooperative agreement by the U. S. Bureau of Mines with the Louisville Gas & Electric Co. The re-forming or partial cracking of natural gas is not a new process, but one which has been employed in the manufacture of city gas for a number of years. However, the apparatus used heretofore was not a water-gas generator containing a bed of ignited fuel, but instead it was a plurality of connected chambers containing spaced and arranged checker bricks, with means for heating the bricks and for admitting the natural gas. The procedure previously followed was quite different from that used during the tests at Louisville; likewise the results obtained were different. It is not uncommon for companies distributing natural gas to provide gas-generating equipment for producing manufactured gas which is used, mixed with natural gas, during periods of peak demand. Because this equipment is idle much of the time, in some instances being in use only for a few days a year, some of the gas companies have considered using it, during off-peak periods, in the manufacture of some gaseous products and for carbon black which might he produced and marketed with profit. There is one plant of this kind at Louisville. Kentucky. Its maintenance in condition ready to be operated is necessary because of the limited supply of natural gas and because of the variation in demand. The engineers of the Louisville Gas & Electric Co. considered in particular the possibility of cracking natural gas in a water-gas generator by injecting the gas into the incandescent fuel bed, thereby producing a gas comprised largely of hydrogen (H2) and carbon black, an appreciable amount of which is entrained in the gas as it leaves the generator, Because power and gas are available at low prices, Louisville was believed to be a satisfactory location for a plant which could use hydrogen. It was evident that this method of treating natural gas might directly benefit the gas company by: 1. Lowering, the cost of manufactured gas.

Jan 1, 1930

By E. C. Lane

This paper is a preliminary report of the results of the Bureau of Mines' twenty-second semiannual survey of motor gasoline marketed in the United States. A more detailed discussion of the whole survey is in preparation and will be published as a companion, report. The second paper, in addition to giving a more complete summary of the data included in this report, will present results of the determination of copper-strip core lion (method 530.22), color (method 10.11), sulphur content (method 520.11) evaporation residue (method 530.1), and gum content as given by the Bureau of Mines steam oven method.9 The retail price at the time the sample was taken and tax will also be stated for each sample. The present paper deals specifically with data relating to gravity, vapor pressure, and distillation. It has been the feeling of some investigators that the practice, followed in previous semiannual surveys, of grouping all types of motor fuel together without discriminating between "competitive price gasoline," benzol blends, Ethyl gasoline, "high-test" fuels, etc., has detracted from their usefulness because the data did not permit drawing conclusions in regard to any one type of fuel, and tended to obscure differences between fuels of the various types. Therefore, in order to remedy this condition, the samples of the present survey have been divided into two groups; one called "competitive-price gasoline" and a second group called "premium-price motor fuels."

Jan 1, 1930

By Jack G. Croeni

A study was made by the Bureau of Mines to determine the influence of high energy-rate deformation on the structures and properties of low-carbon steel, stainless steel, titanium, titanium-6 percent aluminum-4 percent vanadium, beryllium, molybdenum, and tungsten. The purpose of this study was to determine relative formability, the effect of energy and temperature on metalworking parameters and resulting structures, and the properties of materials formed by this technique. Forming techniques were limited to upset forging and direct extrusion on pneumatic-mechanical forming machines. Results show that considerable grain refinement can be achieved by careful control of deformation and forming temperature by high energy-rate techniques. Significant improvements in strength were observed as a result of this refined structure. Approximate deformation resistance as a function of temperature was determined for a variety of materials.

Jan 1, 1966

By M. R. Yenchek

The U.S. Bureau of Mines has determined a method for calculating coal mine portable power cable thermal life for a specified temperature loading. This work was the culmination of a multifaceted research project involving (1) accelerated life tests of insulation and jacket materials and (2) steady-state and cyclical loading of cables. Composite Arrhenius curves were derived for common insulation and jacket materials to identify the key cable quality that precipitates thermal failure. Plots of temperature rise versus current for popular cable sizes were then referenced to develop a correspondence between cable life, based upon thermal degradation and current loading. Predictions of cable thermal life were made through integration over variable load cycles and, consequently variable operating temperatures. This procedure may have utility for both the U.S. Mine Safety and Health Administration and mining machine designers in determining the appropriate cable size for new equipment.

Jan 1, 1991

By G. W. Birge

Fifteen coal samples, representing the Winifrede, Chilton, Alma, No. 2 Gas, Powellton, Eagle, Douglas, Sewell, Beckley, Pocahontas No.4, and Pocahontas No.3 beds in Wyoming County, and five samples, representing the Fire Creek, Pocahontas No.6, and Pocahontas No.3 beds in Mercer County, W. Va., were carbonized at 9000 C by the Bureau of Mines-American Gas Association (BM-AGA) method, and yields of products and physical properties of cokes were determined. Expansion characteristics of the majority of samples were determined in the Bureau of Mines sole-heated oven. Chemical analyses and agglutinating values were determined for all coals. The coals were mostly strongly coking and low in ash and sulfur content. Dry, mineral-matter-free fixed-carbon content of the Wyoming County coals ranged from 63.0 to 83.4 percent. The Mercer County samples were all low volatile in rank. Yields of carbonization products were generally in accord with yields from similar rank coals of the Appalachian region. Because of their expanding tendencies, most of the medium-and low-volatile coals would require blending with lower rank coal for normal coke production.

Jan 1, 1965

By Gary L. Hundley

As part of the U.S. Bureau of Mines program to reduce the Nation's reliance on foreign supplies for critical metals, a procedure was devised to separate and recover critical metals from mixed and contaminated super alloy scrap. The process uses both pyrometallurgical and hydrometallurgical methods to treat the scrap. The mixed scrap is converted to a matte containing 4 to 7 pct S by adding S directly to the molten metal. This matte is then granulated and ground to a minus 35-mesh particle size and leached with an HCI-CI2 solution. This process takes essentially all the Ni, Co, Cr, Fe, AI, and Mo into solution in a 3-h leach, leaving W, Ta, Ti, and Nb (Cb) in the residue. The Mo is recovered from the chloride leach solution by solvent extraction, and the Cr and Fe are recovered together by precipitation. The Ni and Co can be recovered individually by an existing solvent extraction-electrowinning process. The W is recovered by a caustic leach of oxidized Cl2 leach residue.

Jan 1, 2010

By Kenneth L. Rubow, Virgil A. Marple

"INTRODUCTION Respirable dust is defined as the dust which penetrates to the alveolated regions of the lungs. Due to the size selective nature of the particle removal mechanisms in the nasal passages and lung airways, criteria defining respirable particles must be a function of the particle size. Three criteria defining respirable particle penetration are shown in Figure 1. These criteria have been defined by the British Medical Research Council (BMRC), the American Conference of Governmental Industrial Hygienists (ACGIH) and German TBF 50-11 (1).The quantity of respirable particles in an aerosol can be measured by use of two-stage samplers. The first stage consists of a particle preclassifier with penetration characteristics corresponding to one of the respirable penetration curves in Figure 1. The large nonrespirable dust particles are removed from the airstream in the preclassifier and the smaller respirable dust particles pass on to some device which can measure their concentration (the respirable dust concentration).Instrumentation for the measurement of respirable coal mine dust has been limited by the severe conditions existing within the coal mine. The conditions of particular importance are the methane atmosphere, high humidity, and the general non-laboratory type environment. The most severe of these conditions is the methane atmosphere since any electronic or electric powered instrumentation must be intrinsically safe to operate in such an atmosphere.In spite of the difficulty of sampling respirable dust within the mines, many instruments have been developed for in mine use. Although these instruments operate under a variety of principles they generally fall within two categories: personal samplers and area samplers.A personal sampler is worn by the mines while he is performing his duties in the mine. These devices are generally small, light weight and require little power so as not to interfere with the miner's ability to work."

Jan 1, 1988

By L. C. IlsLey

Minin,g Qr col-cu.ttint till:I chines are 1?;\i9ng the _m9t wideiy .used de1sses ()f mining equipment.· These 1T:.i:1Chines ,.--re practicaily t-tl\·operc1_ted eiyher_by compressed .iir or by electric. ·motors. According to &.ta• compiled _ from the 122. issue COAL CATALOG\JE. OJMEINED WITH; OOAL "FIELD 'pf!:fC'TOTl1, bf 7,088. mnes from which reports were obttiined there -are 3895 mines that u.se coal-cutting eql;lipmen:ts,, 'f'hi report lists 20,031: r.ct:lchines, 17,&75 being operated by·elct:i.c.m<;>_tors··:r;id :the remtiinder by compressed i.r motors,· ,-. · ', .. . · .. ··, .. _ ,· .,, .. .. . . . . . : ; "'l t:: On tl.Ccou-nt .. of the wide· use of coc:11-cutting -.:i"cliine_- any Stat!;ls have issued regulationa as "to their operation dnd be to safety precautions that.should be observed J especially in gaseous mines.

Oct 1, 1922

By Peter L. Swanson

This investigation, which began 90 minutes after the February 3, 1995, seismic event, has benefitted from the assistance of a large number of individuals. These individuals provided information, data, analysis, brainstorming opportunities, field equipment, assistance with communication, conducted rock mechanics tests, and provided insight into mining in the southwestern Wyoming trona district. They include Rich Hodgson, Ron Hughes, Larry Refsdal. Mike Weller, John Kolesar, Joe Vendetti, and Rick Casey (Solvay Minerals), Dave Delling (Solvay consultant - former Solvay President), Karl Zipf (formerly with USBM, now with MSHA), Bob Friend, Bob Ferriter, Dave Ropchan, Jerry Davidson (MSHA Tech Support), Don Stauffenberg, Ben Hohler (Wyoming State Mine Inspector&apos;s office), Bruce Presgrave (USGS/NEIC), Chris Wood, Dan O&apos;Connell (Bureau of Reclamation), Sue Nava, Jim Pechmann (University of Utah), John Norgord and members of FMC&apos;s mine rescue team (FMC Corp.), Bill Walter (Lawrence Livermore National Laboratory), Ron Gerlick, Kevin Wood, and Mike Harmel (USBM rock mechanics lab), Jim Case (Wyoming State Geological Survey), and Solvay consultants. In addition, many individuals helped us gather information on other recent large mining-related seismic events in Germany, Russia, and Australia. and other parts of the United States. These individuals include Wolfgang Minkley (IfG Institut fur Gebirgsmechanik, Leipzig), Arnfinn Prugger (Potash Corp. of Saskatchewan), Hartmut Spetzler (University of Colorado/ University of Bayreuth), Sergei Stanchits (Ioffe Poly-technical Institute, St. Petersburg), Rocky Thompson (Cyprus-Amax) and numerous seismologists throughout the Internet.

Jan 1, 2011

By R. V. Ramani, K. Bode

"IntroductionIn part 1 of this paper, the results of the experimental work in a wind tunnel under controlled conditions were presented. To understand the spatial and temporal behaviour of airborne dust under mine conditions, experiments were performed in the Lake Lynn Experimental Mine of the US Bureau of Mines. The mine airway experiments were designed to study the variations of ambient concentrations along the length of an airway, and the deposition rates and deposition velocities in an airway cross section. Other objectives of the study were to investigate the spatial and temporal behaviour of airborne dust with regard to air velocity and particle density, the size distribution of the airborne dust cloud as it travels in the airway, and the size distribution of the dust particles deposited along the airway. Other objectives of the study were to compare wind tunnel results with In-Mine results, whenever appropriate.Experimental ProcedureLocationA complete description of the Lake Lynn Laboratory Mine of the US Bureau of Mines (USBM) can be found in the US Bureau of Mines Information Circular 8911 (Mattes et al., 1983). This mine provides excellent facilities for dust experiments. The airway dimensions are similar to those of a coal mine airway. The mine has a drift (D Drift, see Figure 1) that extends almost 500 meters without interconnecting airways, stoppings, or bends. The D drift measures approximately 6m in width and 2,25m in height.The Lake Lynn Laboratory Mine· is ventilated by a variable speed, 75 kW (100 hp), 28,3 m3/s (60 000 cfm) blower fan installed on the top of the ventilation shaft. Air velocities of 1, 1,3 and 1,8 m/s, respectively, could be obtained in the D Drift. However, the temperature changes at the surface can cause small variations in air quantities and velocities underground. The low background dust level in the mine reduces the problem of sample contamination from other sources of dust. Extended periods of uninterrupted data collection can also be scheduled. Mine airway parameters which are important for the analysis include the dimensions of the airway and the ventilation data such as the air velocity, and the pressure loss in the drift. All these data were acquired during altimeter surveys which were conducted prior to each of the experiments."

Dec 1, 1995

By L. M. Chan, D. R. Carlson, J. H. Johnson

"This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program.The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.INTRODUCTIONDiesel-powered mining vehicles are gaining Popularity in underground coal mines and are almost universally used in underground non-coal mines due to their mobility, flexibility, and higher productivity. However, noxious gases and particulate matter in diesel engine exhaust are a concern because of the potential for being harmful to the health of miners. Diesel exhaust pollutant concentrations out the tailpipe of a mine vehicle change with time due to engine wear, inadequate maintenance, improper adjustments and other factors. This deterioration in pollutant concentrations, if not properly controlled, may adversely affect the air quality in an underground mine. To provide assurance that a clean and healthful work environment are maintained, a program is needed to identify and repair diesel engines that contribute to poor air quality. Also, earlier detection of deteriorated engines will make preventive maintenance possible, thereby eliminating further deterioration and possibly complete breakdown. Preventive maintenance also increases engine life and equipment availability in production which in turn will result in decreased operating costs."

Nov 1, 1995

By J. B. Gayle

A 1/2-ton experimental coke oven was installed ac the Bureau of Mines Southern Experiment Station, Tuscaloosa, Ala., in 1948. Designated as the Tuscaloosa oven, this unit features a 17-inch carbonizing chamber, globar heating elements, and silica-brick walls designed to simulate as closely as possible the carbonizing conditions for commercial slot-type ovens. Because of the small force exerted on the oven walls in most tests conducted to date (probably owing to the practice of charging coals and blends at a moisture content approximating that normal to commercial plants operating in this district), little information has been obtained about expansion properties. Two sole-heated ovens have therefore been constructed and used as supplementary equipment for determining the expansion properties of coals tested in the Tuscaloosa oven. The reasons for constructing the Tuscaloosa oven, the details of design, the operating, characteristics of the oven and the reproducibility of results have been discussed in previous publications. 3 4 5/ The present report deals with the effects of substituting various high- and low-volatile coals for components of a selected base blend carbonized under conditions similar to those normally used for producing foundry coke. Results of tests of 11 coals and 14 blends indicate that several blends tested rave cokes having physical properties very similar to those produced from the reference blend.

Jan 1, 1957

By F. P. Haver

Because of increasing concern with air pollution, the Bureau of Mines has developed a hydrometallurgical procedure to obtain elemental sulfur from chalcopyrite (CuFeS2) by means of the following reaction: CuFeS2 + 3FeCl3 ? CuCl + 4FeCl2 + 2S. Under optimum conditions, 99.6 percent of the copper and 71.6 percent of the iron were extracted in 2 hours from a typical mill concentrate containing 75 percent CuFeS2 and 15 percent pyrite (FeS2). At the same time, 68.2 percent of the sulfur in the concentrate was oxidized to the elemental form. The leach was highly selective; gangue minerals, including pyrite, were not attacked, thus accounting for the relatively low recoveries of iron and sulfur. To obtain these results, the concentrate was ground to 98.9 percent minus 325 mesh, and 300 grams was treated with 1 liter of boiling ferric chloride (FeCl3) solution. The FeC13/CuFeS2 ratio was 2.7. Cement copper containing 99.9 percent copper was recovered from the leach solution by cementation on sponge iron. Excess iron, dissolved during leaching and cementation, was removed from the stripped solution by crystallization. Ferrous chloride (FeCl2?4H2O), obtained as a byproduct, was converted to high-purity ferric oxide (Fe203) and HCI by an oxidizing roast. The hydrochloric acid was then electrolyzed to obtain chlorine, which was used to regenerate the leach solution. The leach residue, which contained ~50 weight-percent elemental sulfur, was treated with an organic solvent to recover the sulfur and cyanided to reclaim gold and silver.

Jan 1, 1971