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By T. H. Dubaniewicz

Many mines rely on toxic gas sensors to help maintain a safe and healthy work environment. This report describes a prototype monitoring system developed by the U.S. Bureau of Mines (USBM) that uses light to power and communicate with several remote toxic gas sensors. The design is based on state-of-the-art optical-to-electrical power converters, solid-state diode lasers, and fiber optics. This design overcomes several problems associated with conventional wire-based systems by providing complete electrical isolation between the remote sensors and the central monitor. The prototype performed well during a 2-week field trial in the USBM Pittsburgh Research Center Safety Research Coal Mine.

Jan 1, 1995

By J. R. White, S. W. Lambert, C. M. McCulloch

Examination of several coalbeds in Walker County, Ala., Cambria, Greene, and Fayette Counties, Pa., and Raleigh and Wyoming Counties, W. Va., indicates that cleat orientations are similar throughout a vertical sequence of strata. Studies of cleat orientation were carried out in underground mines that are operating in separate coalbeds vertically above one another. The data show that over a vertical separation of 100 to 400 feet, the average difference in coal cleat orientation between mines is 04° for the face and 08" for the butt cleat. Variations of coal cleat direction between coalbeds examined in strip-mined areas show similar values. Cleat orientations measured at outcrops agree well with the directions measured underground, suggesting that the amount of vertical separation between coalbeds has little effect on the resulting differences in cleat directions. The largest variation of cleat directions between adjacent coalbeds occurs where a large horizontal distance separates two sample locations. Cleat orientations for deeper coalbeds are most reliable where the data are taken from directly above.

Jan 1, 1976

By L. P. Kleinmann

To control the formation of acid drainage at its source, the Bureau of Mines has investigated the role of iron-oxidizing bacteria in the oxidation of pyrite. In laboratory tests, it was determined that Thio-bacillus ferrooxidans could be controlled in coal refuse using anionic surfactants, with an associated decrease in acid production of about 75 pet. Based on these results, large-scale tests were conducted at an 8-acre active coal refuse area in northern West Virginia and an 11-acre inactive refuse pile in southern West Virginia. Acid production was decreased 60 to 95 pet for 4 to 5 months after application of 55 gal/ acre of 30-pct sodium lauryl sulfate solution. To date, effluent surfactant concentrations have been extremely low. Either a hydroseeder or a road-watering truck can be used to apply the surfactant. Since the surfactant solution must reach the pyritic material to be effective, sites that have been reclaimed are generally not amenable to these procedures. A simple laboratory test is described that provides an estimate of adsorption potential; this can be used to calculate a safe application rate.

Jan 1, 1983

By F. P. Miknis

Previous studies at the Bureau of Mines have shown that broad-line nuclear magnetic resonance (NMR) techniques have potential applications for rapid evaluation of oil-shale deposits. In a continuation of this study the techniques of pulsed NMR have been applied in a similar manner. The basis for the pulsed NMR oil-shale assay method lies in the assumption that the free induction decay (FID) amplitude following a 90° pulse is proportional to the potential oil yield. This assumption was tested on two groups of oil-shale samples, numbering 141 and 263 samples, from two different oil-shale cores. For both groups of samples a small number were selected as calibration samples. Free induction decay amplitude measurements were made on the 141 and 263 samples. The best least-squares regression line was obtained for the calibration samples, and the oil yields of the remaining samples were calculated using the slopes and intercepts obtained in the regression analyses. The agreement between measured and calculated oil yields was good, the indexes of determination being 0.93 and 0.89 for the groups of 141 and 263 samples, respectively.

Jan 1, 1974

By W. W. Adams

Lower accident rates were the outstanding feature. of the second annual sand and gravel safety competition conducted in 1930 by the United States Bureau of Mines in cooperation with the National Sand and Gravel Association. Both the frequency and, severity rates for accidents were greatly reduced as compared with those shown by the first year's contest, that for 1929. Three times as many plants were enrolled, and the number of man-hours of work represented wad more than doubled. Seventy-six sand-and-gravel plants, situated in 20 States, participated in the competition, as compared with 26 plants, located in 13 States, in the year before. The number of man-hours of employment, which indicated the amount of exposure to occupational hazards, was 4,915,592 an increase of more than 100 per cent over, the previous year's total of 2.259,572 hours. The frequents of accidents declined from 74.4 per million hours for all plants enrolled in the first year's contest to 42.7 per million man-hours for all plants enrolled in 1930. The accident-severity rate was reduced from 9.7 days of disability per thousand man-hours of exposure in 1929 to 5.9 days of disability per thousand man-hours of exposure in 1930.

Jan 1, 1931

By James R. McVey

Tests during pillar robbing, longwall operations, and other mining activities indicate that roof-floor convergence rates can be used as an indicator of imminent roof failure. A large number of electrical-mechanical devices have been built to measure convergence as well as convergence rates, but most obstruct mine traffic and are costly and time consuming to install. The Bureau of Mines has designed and is evaluating three types of small ultrasonic units to make these measurements. The new instruments provide nonobstructing measurements up to 35 ft away. The ultrasonic transducers can be attached to a roof bolt, placed in an unsupported area (by means of a toss basket), or handheld. Total distance to the target and rate of closure are displayed digitally to 0.001 ft and 0.01 ft/min, respectively.

Jan 1, 1984

By Ervin P. Fuchs

Volume II of this report presents the vibration data, octave band data, one-third octave band data and narrow band (amplitude versus frequency) data for ten mining machines. These ten mining machines include a Goodman 968-2 Loading Machine, a Lee Norse 245 Continuous Miner, a Jeffrey 120L Continuous Miner, a National Mine Service 3080 Continuous Miner, Acme D-1 Roof Bolter, a Lee Norse 265 Continuous Miner, two Jeffrey Locomotives, a Joy CD-71A Coal Drill and a Jeffrey 100L Auger Miner. Volume J of this report presents the effects of underground environment and loading conditions on noise levels of coal mining equipment

Jan 1, 1979

Compare the fire endurance of paneled steel stoppings with that of traditional concrete block Stoppings. Background Permanent stoppings or partitions arc used in mines to separate ventilation airways. The ability of stoppings to retain their structural integrity for a minimum length of time under lire conditions and prevent the spread of flame and toxic combustion products to an adjacent airway is critical. The success of miners in reaching safety during a fire depends largely on the presence of uncontaminated airways. Traditionally, permanent stoppings for coal mines are constructed of concrete blocks. Recently, paneled steel stoppings that satisfy many of the requirements demanded of permanent stoppings, such as incombustibility and strength, have been introduced. Their use also introduced concerns such as the ability of a steel stopping to maintain its ventilation control function when exposed to a fire and the potential that the fire could transmit enough heat through the stopping to ignite combustible materials on the unexposed side. To address these concerns, the Bureau of Mines investigated the fire endurance of galvanized steel and concrete block stoppings.

Jan 1, 1989

By Edward F. Divers

A new nonclogging water spray system for continuous-mining machines has been developed under contract with the Bureau of Mines. This paper presents installation and operating guidelines for the system, which consists of improved and easily maintained machine-mounted hardware, including an inline Y-strainer, a hydrocyclone, a backup filter, and two quick-opening valves for flushing particulates from the strainer and hydrocyclone. Underground tests with continuous-mining machines have shown that when properly installed and maintained, the new sys tern virtually eliminates nozzle clogging and thus greatly reduces spray maintenance. The sys tern is relatively inexpensive and has been installed on typical continuous-mining machines for a total cost under $1,000.

Jan 1, 1976

The Bureau of Mines has conducted considerable research to improve life support technology for underground mining applications. This proceedings volume presents several new developments that may help increase the chances of mine workers in surviving underground disasters. Several papers address the performance of present self-contained self-rescuers (SCSR's) and provide proposed guidelines for the design and testing of a second-generation SCSR. Improvements In the safety and effectiveness of mine rescue and recovery operations are described, including the design of a low-profile rescue breathing apparatus and a rescue team helmet.

Jan 1, 1987

By Potter G. M.

Ore-dressing tests were conducted on a sample of ore submitted by the Richmond Hill Mining Co. of Lead, S. Dak. as a part of the Bureau of Mines program for investigating potential domestic sources of manganese. Half of the sample was taken from the 300-foot level and half from surface cuts. The problems involved were liberation and rejection of silica and iron and removal of lead, Silver, and gold from the manganese concentrates. Although a portion of the silica and iron oxides was too intimately associated with manganese minerals for rejection by ore-dressing methods, thus limiting recovery of high-grade concentrates, the Richmond Hill ore was found amenable to simple gravity methods of concentration for producing intermediate-grade products. By jigging and tabling, 73.8 percent of the total manganese was recovered in a product that, when sintered, assayed plus 40 percent Mn. Lead, silver, and gold were successfully removed from gravity concentrates by a chloridizing roasting treatment.

Jan 1, 1948

By J. W. Adams

Measurements of surface magnetic field noise were made at various locations over the Geneva Coal Mine near Price, Utah, on June 12, 1973. The locations selected were on the surface over emergency locator beacons underground at depths between 3S0 meters (1150 ft.) and 488 meters (1600 ft.). The surface terrain where these measurements were made was mountainous, and access was difficult. There were no power lines within several miles, and the weather was clear; therefore, the magnetic noise levels were about as low as will normally occur. Results of measurements of distant sferics indicate rather sharp cutoff frequencies below which broadband, impulsive noise is attenuated. The mechanism of propagation for this noise above the daytime cutoff frequency of 3500 Hz and the nighttime cutoff frequency of 1700 Hz is deduced to be a waveguide formed by the D or F layers of ionosphere as an upper plane and the earth as a lower plane.

Jan 1, 1974

By E. G. Davis

The Bureau of Mines studied tailings samples from 11 large-scale western copper operations to determine the potential for recovery of rutile and other critical and strategic minerals. Up to 15 pounds per short ton (lb/st) Ti02 was found ion these samples; however, only 9 to 44 pct of the Ti02 was liberated rutile. For one sample, gravity preconcentra-tion, grinding, and flotation recovered 34 pct of the Ti02 in a 54.8-pct-Ti02 concentrate. Over 0.38 Ib/st W was found in some of the tailings sampleso Scheelite was identified as the major W mineral. Nine of the eleven samples contained about 0.02 to 0.18 Ib/st Co. Pyrite was the principal Co-bearing sulfide mineral, with Co contained in about one-fifth of the pyrite grains. Up to 30 pct of the Co was concentrated in a bulk sulfide flotation concentrate.

Jan 1, 1988

By William Seymour, L. D. Schmidt, J. W. Myers, W. T. Reid

"This investigation was conducted by the Bureau of Mines as part of a program of the Solid Fuels Administration to encourage the utilization of anthracite fines, the objective being to determine the practicability of using anthracite fines in the manufacture of packagedThe experimental loss of packaged fuel covered by this report were made at a commercial plant using the Glenn Smith process and ordinarily making packaged fuel from Pocahontas screenings. These lots included several made from straight antimacite mines and others made from various blends of anthracite fines with four different bituminous coals. In all cases an asphalt binder was used. Determinations of the physical properties and the cobustion characteristics o the various samples of packaged fuel were made by the. Bureau of Mines at the Central Experiment Station.The physical tests indicated that a packaged fuel of sufficient strength for ordinary handling can be made from straight anthracite coal or from a wide variety of blends of anthracite fixes with bitunimous coal, using asphaltic binder. However the combustion tests indicated that packaged fuel made from anthracite alone tended to crumble excessively during burning and that as much as 30 to 50 percent of a caking coal may be required In the mixture to produce a block having satisfactory combustion characteristics.The authors wish to acknowledge the. splendid cooperation of Messrs. H. W. Kelly, J. L. Mooney and C. H. Stoss of Columbus, Ohio, who were chiefly responsible for obtaining the materials and making all the arrangements necessary for the production of the packaged fuel for testing.Thanks are due to the officials of Carnegie Institute of Technology for the use of their Olsen. Testing Machine and to H. M. Cooper and W. A. Selvig of the Bureau of Mines for analyses and tests."

May 1, 1946

By H. J. Heinen

This report summarizes preliminary research studies by the Bureau of Mines in electrowinning molybdenum directly from pure or impure molybdenum trioxide (MoO3) by fused-bath electrolysis in an open graphite cell without need of a protective inert atmosphere. A formulated electrolyte of the tertiary system containing 41.6 percent sodium pyrophosphate, 16.7 percent sodium tetraborat, 33.3 percent sodium chloride, and 8,4 percent molybdenum trioxide, by weight, electrolyzed at 1,000° C,, gave excellent results. Current density studies were made over a range from 20 to 260 amperes per square decimeter. Current efficiencies of 80 to 90 percent were obtained over the entire range. Yields up to 500 grams of molybdenum per kilowatt-hour were obtained. Higher current densities, however, reduced yields and produced a finer grained metal. The two most important facets in electrowinning molybdenum from MoO3, in an open cell, are temperature and electrode spacing to minimize or eliminate the formation of the suboxide MoO2, the major source of oxygen contamination. At temperatures of 1,000° C. and higher, together with the proper spacing of the electrodes, formation of oxides are practically eliminated. Molybdenum metal electrowon from pure MoO3 was 99.9 percent pure and contained 0,056 percent oxygen and 0,007 percent carbon. This metal, when arc-melted, had a Vickers hardness number of 175 and contained 50 parts per million oxygen and less than 10 parts per million carbon. Molybdenum metal electrowon directly from an impure MoO3 containing 90 percent MoO3 resulted in a metal of 99.8 percent purity.

Jan 1, 1961

By J. D. Lane

The U.S. Bureau of Mines is conducting research on guidance systems for computerized haulage in underground mines. This report describes the process of component selection, installation and testing, perception algorithm development, and steering control algorithm development, to produce a real-time steering control system for an articulated haul truck for underground mining. Ultrasonic transducers were mounted on the truck to provide perception data by measuring the distance to the ribs. Linear potentiometers mounted inside the steering cylinders measured the steering angles. Algorithms, implemented on an inexpensive, robust onboard computer system, analyzed the data and controlled the steering via an electro-hydraulic proportional valve. The steering algorithm presented follows a zone defined by the relative position between the truck and a rib. Experimental verification of the ability to follow the zone in a test corridor on the Colorado School of Mines campus is presented. The automatic steering system successfully negotiated straight sections, curves, and the transition zones between straight and curves with the truck in first and second gears. The resulting real-time automatic-steering system can be applied to many underground articulated machines.

Jan 1, 1994

By Michael Sokaski, M. R. Geer, H. F. Yancey

This report is one of a series describing investigations by the Federal Bureau of Mines of the performance of various types of coal - cleaning equipment ; other reports in the series are listed in the bibliography . The information in these reports is useful to the coal industry and the manufacturers of coal - cleaning equipment in several ways : First , it assists the coalpreparation engineer who is planning a new plant to select the type of process best suited to the requirements by enabling him to forecast the yield and quality of clean coal obtainable with each type of equipment . Second , the information serves as a yardstick by which the performance of a plant can be judged and thus helps determine whether it is operating at satisfactory efficiency . Both these functions promote better coal - preparation practice ; that is , they help provide coal of more suitable quality for the market and likewise minimize the waste of good coal . This serves the interest of conservation with which the Bureau is vitally concerned . The present report deals with three plants using the Tromp dense - medium process , named after its inventor , K. F. Tromp , who developed the process in the Netherlands in 1936.5/ Selection of this particular dense -medium process for investigation was entirely a matter of convenience , and reports dealing with other dense -medium systems are planned for the future . Two baths are employed in one of the plants investigated . The first of these , handling 6- to 3 - inch coal , exhibited an exceptionally sharp separation between coal and impurity . This was characterized by an error area of 12 and a probable error of 0.023 . In the second bath , treating refuse from the

Jul 1, 1960

By V. A. Marple, K. L. Rubow

"Filter samplers are one of the simplest methods and, in some instances, one of the only methods that can be use to obtain samples of particulate matter suspended in a gaseous medium. Once collected, particles are normally analyzed directly on the filter by gravimetric, chemical or microscopic techniques. However, it is sometimes desirable to resuspend the particles in an airstream for analysis. This would be the case if the size distribution of the particles were to be measured using one of many particle sizing techniques such as inertial classifiers, optical particle counters or the TSI Aerodynamic Particle Sizer CAPS).A ·technique has been recently developed whereby one can resuspend particles from filter samples in an airstream. The technique has been used for the resuspension of coal dust from filters. The resuspended particles were then introduced into the APS. This development was necessary since an APS can not be taken directly into an underground coal mine. For this application, particle samples are collected on membrane filters in the underground mines. The mass concentration of the particles determined through gravimetric analysis. The particle size distribution was tl1en determined by resuspending the particles and passing them through a TSI Aerodynamic Particle Sizer (APS). Excellent agreement has been obtained between the size distribution directly measured underground with a cascade impactor and that measured from the resuspended particles. For this experiment, an open-faced filter sampler was placed adjacent to the cascade impactor in the n1ine. The particles collected on the filter were resuspended in the laboratory and Measured with the APS.A venturi aspirator is used in the apparatus developed for resuspending the particles. The venturi has a small diameter capillary tube placed in the venturi throat. High velocity air flow is passed through the venturi, thereby, creating a low pressure region at the exit of the capillary tube. The low pressure draws air through the tube. The filter with deposited particles is located at the inlet to the capillary tube where the air flow into the capillary resuspend the particles. Once airborne, the particles are deagglomerated as they pass through the high velocity air flow in the venturi throat."

Jan 1, 1989

By T. M. Barton

This paper presents several case studies in which a mechanics-based boundary-element program is used to back-calculate the surface subsidence associated with various panels at several northern Appalachian coal mines. The program used in this case study is called LAMODEL, which incorporates a frictionless, laminated overburden into a general-purpose displacement-discontinuity code primarily designed for calculating the stresses and displacements in coal mines or other thin-seam or vein-type deposits. In this paper, the program is used to calculate both the underground convergence and the resulting surface subsidence at five longwall panels and a room-and-pillar section. The fitted subsidence from the model is compared with the field measurements and analyzed. The results from this work show that the LAMODEL program is not as accurate as available empirical subsidence-predictive methods: the expected correlation between the geology and the optimum input parameters is not evident. However, for a mechanics-based program, LAMODEL does provide moderately accurate subsidence calculations, and it is one of a few programs that can even attempt to practically calculate both underground stress and convergence and the resulting surface subsidence.

By R. R. Backer

The Bureau of Mines, in cooperation with Washington Irrigation and Development Co. (WIDCO), evaluated the dewatering of fine coal-refuse slurry using chemicals and various types and combinations of drains in natural earth impoundments. About 40 lb of lime and 2 lb of polymer per ton of dry solids were mixed with the underflow from the preparation-plant thickener. Clear, free water was immediately liberated from the slurry. The percent solids by weight of the slurry increased from about 17 to 30 immediately, and after 5 days increased to 45 wt-pct. This indicates a threefold reduction in total volume after 5 days from 172 cu ft/ton solids originally to 56 cu ft/ton solids.

Jan 1, 1981