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By H. S. Chiang, Zhao. Y. F., G. C. Sun, S. S. Peng

"Chiang; H. S. West Virginia UniversityPeng, S. S. West Virginia UniversitySun, G. C. West Virginia UniversityZhao, Y. F.West Virginia UniversityDust sampling was performed in two longwall faces working in two separate seams. Instantaneous dust samples were measured by RAH's. for various locations In the longwall faces. Preliminary analysis of the data shows that in addition to the shearer's haulage speed, there are four major factors that influence the airborne dust distribution in longwall face areas: locations with respect to the position of the shearer's cutting, hardness of the materials, characteristics of water spray, and roof conditions. This paper presents the effects of those four parameters in detail.INTRODUCTIONA research project was initiated in September 1983 to measure and construct .a dust distribution map for the longwall face. During the first year, airborne dust samplings were performed in two longwall panels located in northern and southern West Virginia and working in the Pittsburgh and Eagle Seams, respectively. The physical parameters and equipment employed for both panels are 1 isled in Table 1. Figure 1 shows the detailed characteristics of the coal seams. Notice in both panels floor cutting was involved either to gain sufficient mining height or to reduce the adverse effects associated with a soft floor.The purpose of the research is to define the dust distribution at any instance in the longwall face area so that proper working positions can be determined and/or effective dust control techniques can be developed.This paper presents the partial results obtained during the first year."

Jan 1, 1988

By R. Sainath, Wils L. Cooley

Continuous monitoring of ground bed resistance is essential to insure a low-resistance path for fault currents, lightning strokes, and electrostatic discharges. This paper explains the salient features of the continuous ground bed monitor and its applications. The importance of a low-resistance path to ground is highlighted. Sample readings obtained with the ground bed monitor are included, and typical applications of this instrument are illustrated. This effort was supported by the U.S. Department of Interior's Bureau of Mines under USBM grant G0144138.

Jan 1, 1979

By G. R. Friggens

A nuclear method for continuously monitoring the coalbed and ash levels and void formation in commercial-scale, fixed-bed, pressurized gas producers is proposed. Measurement of gamma ray transmission through the coalbed is the basis of the method. The coalbed level is monitored by detecting the trans-mission of gamma rays from a 1 to 2 Ci Co-60 source positioned on the outside wall of the vessel. Coal bridging or, alternatively, ash level is monitored by a 10 Ci Co-60 source at the center of the coalbed. Source activities and geometries are calculated for a 12-foot-ID producer designed to operate at 350 psi. Source capsule and detector specifications and operational safety are also discussed.

Jan 1, 1973

By R. M. Gammell, S. H. Lorain

The Anderson prospect is one of a number of properties investigated by the Bureau of Mines during the course of preliminary studies of the lead-zinc districts of northern Stevens County, Washington. examined by W. R. Green, an engineer of the Bureau of Mines, in June 1944. This examination was supplemented in late 1944 and the spring of 1945 by pre- The property was first liminary angle-dozer trenching and core-drilling. A second examination of the property was made by the junior author in November 1945. The data obtained in the course of these studies is presented in the following report.

Mar 1, 1947

By Robert P. Vinson, Fred N. Kissell, Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

By Noel N. Moebs

The Bureau of Mines measured surface subsidence above four small coal mine room-and-pillar sections in southwestern Pennsylvania, to obtain preliminary information on the magnitude and character of selected parameters, such as angle of draw and maximum subsidence, which are essential to the development of subsidence prediction methods. Data varied widely at the four sites; this is attributed to local geologic and mining conditions. Surface deformation at each site was of a magnitude normally associated with severe structural damage.

Jan 1, 1982

Develop a means for estimating vertical stress conditions in or around an underground mine so that appropriate measures for ground control can be taken before hazardous conditions arise. Background High vertical stress in an underground mine could cause or enhance hazardous ground control conditions which might lead to accidents, fatalities, and loss of reserves. An understanding of the vertical stress conditions at the mining level would allow a mine operator to take precautions that will minimize the occurrence of ground control problems. A knowledge of the underground stress conditions prior to mining could be used as an aid in future mine plan development to avoid or minimize ground control problems. Approach The Bureau of Mines developed a computer program for calculating the vertical stress resulting from the pressure of overlying rock masses on a mine or geologic surface at various depths.

Jan 1, 1990

To improve mining safety and efficiency by providing a practical way of detecting faults and channel sands that disturb coal seams. Approach A seismic system using a shallow blasthole has been developed and tested. How It Works A small shock is caused in a shallow hole, sending seismic waves through the ground. These waves are reflected from the top of the coal seam, acid are detected by a line of geophones on the earth's surface. Dampening of the seismic signals by channel sands and other discontinuities in the seam is detected and recorded. See Figure 1. The seismic shock wave can be produced by exploding small charges, dropping a weight, firing a gas gun, or actuating a vibrator. Depending on the soil cover, the shock is usually generated in shallow vertical holes about 10 feet deep. Hole depth depends on the soil mantle thickness because it is preferable that the seismic shock originate below that layer.

Jan 1, 1976

Control the release of ground-water into active underground coal workings by short-term pumping from dewatering wells sited on fractures. Approach The sudden release of fracture-stored groundwater into underground coal workings often occurs when mine workings are developed beneath fracture valleys, Pumping from fracture trace-sited dewatering wells, prior to development of the underlying workings, can be an efficient means of intercepting fracture-stored groundwater before it is released into the mine. Dewatering operations are discontinued once the underlying mine workings have been fully developed, and the maximum possible reduction in fracture storage has been achieved through pumping. How It Works An aerial photographic technique known as fracture trace analysis is used to site dewatering wells on rock fractures in a valley bottom. Downhole caliper and temperature logs are used to assess the fracture flow potential of each dewatering well drilled.

Jan 1, 1987

To facilitate compliance with title 30 CFR 75.1001-1(b), which requires testing and calibrating of trolley line automatic circuit interrupting devices at intervals not to exceed six months. Approach Calibration of a circuit breaker ideally implies the passage of the expected fault current through the sensing circuit, and observing a successful circuit interruption at the preset level within a specified time. On trolley lines, the required current may be a few thousand amperes, with maximum duration well exceeding one-tenth of a second. Any method of obtaining this calibration current Involving the trolley wire can contribute to wire sagging and other permanent damage to the haul-age system due to the high energy dissipated during the test. Also, control to assure that exactly the required level and duration of current flow is obtained implies the use of equipment which is simply not available In the ordinary mine. Under a Bureau of Mines contract, a circuit to achieve the necessary calibration pulse was conceived and built. How It Works Two prototype units were fabricated and have been field tested by MSHA technical support engineers in under-ground mines. The equipment consists of an electronics Package 20 x 24 x 8 inches and weighing 93 pounds, including a side-mounted circuit breaker, with a set of 8 foot long detachable, AWG #4/0 leads with plier-type clamps. The total lead assembly weighs 21 pounds.

Jan 1, 1981

By C. P. Hood

"The amount of ash in anthracite coal interests every buyer, and occasionally produces caustic comment, but there is a lack of authentic figures that will take the subject out of the realm of opinion and agitated fancy and. give a true picture of the quality of coal actually delivered. What per cent ash is to be expected when the coal is good, and when have we a right to make serious complaint?During the past summer the Bureau of Mines took 127 samples of 1000 pounds each, representing nearly 30,000 tons of anthracite is dealers' yards in seventeen cities in the State of Massachusetts. There were three objects in view, to discover the average and the variation in amount of ash in anthracite in some easily described area; to demonstrate standard sampling methods, and to learn something about the feasibility of itinerant coal sampling. Massachusetts was selected because its principal cities could be visited in a single season. There also appeared need for demonstration of standard sampling of coal, since a coal quality law had been passed in the State, to be administered by those unfamiliar with coal sampling."

Feb 1, 1924

Protect rescue workers fighting fires or mine personnel temporarily working in hot environments from heat stress. Approach A specially designed ice-cooled vest is worn while working in hot environments where cooling the mine air is not possible. How It Works The vest holds a total of 44 individual ice cells in packets that are firmly held near the wearer's skin. These ice cells remove heat from the wearer, reducing heat stress and increasing comfort. The locations of the ice cells and packets are shown in the diagram. The vest is constructed in three layers with the outer layer being aluminzed fiberglass cloth. Its aluminized surface reflects radiated heat, and its fiberglass cloth provides fire resistance and strength.

Jan 1, 1979

By C. E. Brechtel

Cooperative research efforts by the Bureau of Mines and Agapito & Associates, Inc., Grand Junction, CO, used a one-dimensional, finite-element computer model to simulate turbulent mass transfer in face ventilation of oil shale mines. The objective was to study the dilution of methane released by rubbled oil shale during blasting. A methane release rate function was developed from the back-analysis of field measurements, and the finite-element model was calibrated using tracer gas characterization data from tests of full-scale face ventilation systems.

Jan 1, 1989

Now you know why there is concern about mine illumination. You have some idea about how the human eye works and about the problems of glare, peripheral vision, and accommodation. And you know that lighting in a mine presents special problems because of the dark surroundings and low reflectance. This chapter describes what can be done to improve conditions. This chapter begins with a short discussion about Federal Standards on mine lighting -- what they are and what is being done to carry them out. The chapter then describes different types of lamps that can be used for mine lighting, and discusses their advantages and disadvantages. Finally, the chapter lists some things that you can do personally to improve lighting, or can point out to others so that improvements can be made. The Federal Government is doing its part to improve mine lighting by establishing regulations. Lamp manufacturers are constantly studying new lamps to provide better equipment. And your company will do its part to comply with regulations. Better lights may not be here yet, but they will be soon. But in the end, you are the one who will be using the lights, and you are in the best position to see the improvements. You are also in the best position to see and tell others where further improve¬ments can be made.

Jan 1, 1976

By C. E. Armantrout, H. Kato, M. I. Copeland

The data collected during this investigation indicate that the chromiumgadolinium system has extensive liquid immiscibility and one eutectic point . Liquid immiscibility occurred at temperatures above the monotectic isotherm , 1,830 ° C , which extended from less than 0.25 to about 85 weight - percent gadolinium . The eutectic was at 96 percent gadolinium and 1,170 ° C. Gadolinium and chromium were the only phases in this system . There was a solid solubility of less than 0.25 percent gadolinium in chromium at 1,730 ° C and less than 0.10 percent chromium in gadolinium at 1,160 ° C. The alloys were prepared by nonconsumable - electrode arc - melting , and the alloy system was investigated by heat treatment , metallography , thermal analysis , and X- ray diffraction . All the melting , heat treatments , and thermal analyses were conducted in a vacuum or in helium because of the reactivity of chromium and gadolinium with the components present in the atmosphere at elevated temperatures .

Jan 1, 1964

By Henry E. Blake

Defluorination studies on refractory fluoride - bearing compounds and minerals , particularly on partly defluorinated residues from high - temperature pyrohydrolysis , required a dependable and reasonably accurate analyticalcontrol method for the analysis of fluorine . The difficulty in liberating fluorine from the fluorides of metallic elements such as aluminum, zirconium , and rare earths by steam- distillation can be largely overcome if the distillation is made from a sulfuric - phosphoric acid solution of a sodium carbonate fusion of the sample material and if the distillation temperature is maintained at about 155 ° C. The data presented in this paper show that liberation of fluorine by this method is more complete and proceeds more rapidly than by usual distillations from perchloric or sulfuric acid alone or a mixture of phosphoric and perchloric acids . Fluorine in amounts ranging up to about 140 mg can be recovered by collecting only about 300 ml of distillate . Determination of fluoride in the distillate is made by the usual thorium nitrate titration .

Jan 1, 1963

The instrumentation specification in the National Academy of Engineering (NAE) report of March, 1970, set forth some rather general guidelines that the seismic surface system should follow. The fact that there was no comparable equipment in existence at that time, and the need to produce a system from presently available equipment, was spelled out in that document. The features that the system should include were listed, and included: • Quick and simple deployment • Portability • Battery-powered operation • All-weather operation • Computational simplicity and speed • High reliability and long shelf-life • Dual service for location and communication • Adaptability to widely varying seismic velocities. topography, and geologic structures • Minimum maintenance • Capability of continuous operation for extended periods, and • Reasonable cost Since that report, there has been a substantial amount of field work addressing the trapped miner detection and location problem carried out by Westinghouse Corporation under contract with the Bureau of Mines. Two complete surface systems have been designed, built, and field tested and substantial documentation has been produced on the mine environment and background noise using these systems. These systems, built from off-the-shelf equipment, have been designed with maximum flexibility in mind in order to explore what con¬figuration a field unit should have.

Jan 1, 1974

By Erica E. Hall, Robert H. Peters, Charles Vaught, Jon C. Volkwein

Coal workers’ pneumoconiosis is the leading cause of death due to occupational illness among U.S. coal miners. This disease is caused by miners’ exposure to excessive levels of respirable coal mine dust. A personal dust monitor (PDM) has recently been developed to provide near real-time feedback to miners regarding the level of respirable coal dust in the air they breathe. The main objective of this report is to document coal miners’ reactions to this device and how they make use of the information it provides. It summarizes a field study by the National Institute for Occupational Safety and Health that documented the opinions of 30 miners at 4 underground coal mines concerning the use of PDMs.

Jan 2, 2008

By Yael Miron

Coal mines that undergo self-heatings, and specifically mines that sustain both floor heave and self-heatings, would benefit from the use of sealants to minimize air ingress to susceptible areas. The U.S. Bureau of Mines (USBM) evaluated three sealant systems for this purpose, bentonite-water mixtures, silicate gel, and guar gum gel. The guar gum-based gel was the only sealant that possessed the desired properties of elasticity, ease of preparation, adaptability to the mine, and a long life. In addition, since the gel consists mostly of water, it could quench or cool nearby heatings. Optimal formulations were determined in laboratory tests, and then tested in the USBM Safety Research Coal Mine. Two for-mulations resulted in stable gels that lasted for at least 12 months in the mine. Semicontinuous preparation of gel using an eductor was evaluated and appears feasible. Although guar gum gel is expensive, selective use to prevent heatings in specific areas would be cost-effective, both in terms of productivity and enhanced mine safety.

Jan 1, 2010

Provide ear protection which allows normal, unaltered hearing at low noise levels, yet protects the wearer from excessive noise. The Approach: A commercial earmuff with integral speakers has been adapted with a special amplifier so that low sound levels are not affected, but higher noise levels automatically reduced. How It Works: The discriminating earmuff developed by the Bureau of Mines has two modes of operation. In the first mode, where input sound levels are less than or equal to 83 decibels, the wearer will perceive noise at its actual level. For inputs in excess of 83 decibels, the second mode of operation begins and the sound perceived by the wearer is progressively attenuated, or reduced, as the input level is increased. A recognizable difference still exists between two adjacent sound levels enabling the wearer to differentiate between them.

Jan 1, 1975