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By F. Garcia, J. Cervik

Recent advances in the commercial separation of gases using membranes have renewed interest in the possibility of applying this technology to the recovery of methane ( CH4 ) from mining operations . This Bureau of Mines report briefly reviews the history of the development of membranes for gas separation , the theory of how they work , and their application to the separation of methane from air and associated problems . However , methane -air mixtures are difficult to separate with membranes because the pertinent gas couples , 02 - N2 , 02 - CH4 , and N2 -CH4 , have poor separation characteristics , as indicated by their separation factors of about 3 or less . Even if these separation factors were substantially higher , there is doubt that methane could be recovered economically from the low concentrations in mine ventilation exhaust ( 2 vol pct or less ) . The exhaust pressures are not sufficient for adequate separation . The power cost of compressing the methane recovered . these mixtures would far exceed the value of New discoveries could make separation of gob hole methane - air mixtures practical . These mixtures have much higher concentrations of methane (from 30 to 100 vol pct ) ; however , for safety reasons , be limited to gob gas with 60 vol pct CH4 or more .

Jan 1, 1988

This Technical Memorandum Report is a collection of three working memoranda, prepared during the course of our work for the Bureau of Mines and bound together for convenient reference. These working memoranda present preliminary performance estimates, for baseband voice and narrow- band through-the-earth electromagnetic communications systems of principal interest to the Bureau, for operational/emergency mine communications. The calculations were prepared to obtain early indications of the feasibility and governing parameters of such communications systems. They are based on limited, but pertinent, coal mine electromagnetic noise data acquired to-date by Bureau of Mines contractors; and of theoretical signal-attenuation characteristics for two transmitter antenna types of present interest to the Bureau. The memoranda examine the cases of baseband voice and narrowband communications for uplink and downlink transmissions, for frequencies up to 3kHz. Downlink transmissions are via a horizontal wire antenna, up- link transmissions via a vertical-axis loop antenna, for typical mine depths of 300, 600, and 1000 feet. Representative coal-mine overburden conductivities of 10-2 mhos/meter (moderate and common) and 10-1 mhos/meter (high) were used; for voice and narrowband, 10-1 for narrowband only. Examples of high, moderate, and low; surface and subsurface; harmonic and broadband-impulsive noise conditions were taken from NBS and Westinghouse (WGL) mine noise data, together with examples of high- and low levels of ELF atmospheric noise taken from M.I.T. Lincoln Laboratory data. These feasibility calculations are not intended to serve as definitive and complete treatments, but as a starting point: to establish first-order estimates of the magnitude and variability of transmitter power requirements under different noise, overburden conductivity, and mine depth conditions; to identify relationships, conditions, or frequencies that are likely to limit or enhance system performance; to reveal items requiring further investigation and data still required; and to suggest practical methods for optimizing system performance. These objectives were met by the calculations. Simple experiments to support these calculations can and should be carried out; together with more detailed investigations of specific modulation, coding, noise-suppression, voice-compression and signal-conditioning techniques, aimed at producing through-the-earth operational/emergency mine-communication systems that are not only effective, but practical and economically sound.

Jan 3, 1972

By F. Cherpereel, R. Gabillard, J. P. Dubus

We present an electromagnetic method taken from the well known radiogoniometer that allows us to locate at the surface of the ground the vertical axis of a magnetic antenna transmitter buried at a depth h in the earth. The method and the equipment achieved are called R. E. P. E. (Relevé Electromagnétique de Points Enterrés). They are daily used to accurately survey old quarries by using triangulation instruments at the surface of the earth rather than in galeries where the setting difficulties considerably reduce their accuracy and increase the work length. The results of several surveys allow us to give the optimum working conditions of the instruments and show that, when the transmitter is at a 20 meters depth, its position is known at the surface with an error lower than 1 centimeter. The power transmitter is of about 8 watts and we can find its location with an error smaller than 1 meter when buried at a depth of about 100 meters. This equipment may be successfully used for location of subsurface miners. The space surrounding the transmitter must then be free from ferromagnetic bodies.

Jan 1, 1973

By Thomas P. Holden, Todd M. Ruff

Problem: An average of three workers a year are killed in surface mining operations when a piece of haulage equipment collides with another smaller vehicle or a worker on foot. Another three workers are killed each year when haulage equipment backs over the edge of a dump point or stockpile. Devices to monitor the blind areas of mining equipment are needed to provide a warning to operators when a vehicle, person, or change in terrain is near the equipment. Method: A proximity warning system (PWS) based on the global positioning system (GPS) and peer-to-peer communication has been developed to prevent collisions between mining equipment, small vehicles, and stationary structures. Results: A final system was demonstrated using one off-highway haul truck, three smaller vehicles, and various stationary structures at a surface mining operation. The system successfully displayed the location of nearby vehicles and stationary structures and provided visual and audible warnings to the equipment operator when they were within a preset distance. Summary: Many surface mining operations already use GPS technology on their mobile equipment for tracking and dispatch. Our tests have shown that it is feasible to add proximity warning to these existing systems as a safety feature. Larger scale and long-term tests are needed to prove the technology adequately. Impact on Industry: A PWSs that incorporates a combination of technologies could significantly reduce accidents that involve collisions or driving over an edge at surface mining operations.

By R. R. Brandenthaler

A series of open-flow tests was conducted in the Chickasha gas field, Grady County, Oklahoma, during June, 1927, under the direction of the U. S. Bureau of Mines and at the request of the Oklahoma Corporation Commission. The purpose of these teats was to determine whether or not any differences existed in the open-flow volume of a gas well when taken through well-head nipples of different diameters, and further, to establish if possible a relationship between open-flow volumes taken through well-head nipples of various diameters. The open flow of a well is the volume or quantity of gas, measured under standard conditions, that a well will produce when open to the atmosphere. There are several methods used for determining the open flow of wells; some of the methods are more suitable under certain conditions than others. The Pitot tube method is the simplest, is applicable to almost any condition, and is the one most commonly used. In the tests described in this paper no attempt was made to compare the Pitot tube method with the minute pressure measurement method or the orifice measurement method.5

Jan 1, 1928

By McHenry Mosier

The Anson Bette manganese mine, with two prominent manganese-bearing outcrops in schist, has attracted considerable attention for its variety of manganese minerals and its possibilities as a potential source of manganese. Little mining was done prior to 1925, when the present owner acquired the property, and operations since that date have been intermittent. Mine workings are open cuts with a maximum depth of 35 feet. The two outcropping ore deposits are irregular, pipelike bodies about 500 feet apart. As nothing was known of the grade or extent of mineralization in depth, four holes totaling 1,072.5 feet of bore Were diamond-drilled by the Bureau of Mines in the summer of 1943, with the results shown in figures 3 to 6. In.1945 a geophysical survey was run to map the magnetic anomalies in the manganese-bearing belt as a means of determining the locations of manganese deposits. Positive correlation of magnetite and manganese ore was not obtained.

Jan 1, 1949

By Thomas A. Morgan, Louis A. Panek

This report describes a method for determining the stress in rock based on a requirement for static equilibrium ; namely , that the total load on a sufficiently large area must remain constant even after a drift or stope is mined in the area . The method is based on mathematical relationships that are independent of the elastic properties of the rock and the stress distribution near the underground opening . In addition to determining the preexisting stress (before mining ) , the method described can be used to determine the change in stress due to mining .

Jan 1, 1963

By D. A. O'Keefe, M. M. Wong

To obtain beryllium metal of higher purity , flakes produced from electrorefining scrap metal were used as cell feed for a second cycle of electrore fining at 500 ° C in an electrolyte composed of 51.7 mole - percent LiCl , 36.9 molepercent KC1 , and 11.4 mole - percent BeC¹ · Metallic impurities in the flakes totaled more than 108 ppm , the metallic impurities in the metal obtained from the two - cycle electrorefining were , with the exception of 35 ppm of calcium , below the spectrographic determination limits .

Jan 1, 1964

By R. H. Fernald

In investigating general problems that relate to the fuel resources of this country, and in testing fuels belonging to or for the use of the Government, the Bureau of Mines has given considerable attention to the efficiency and economic value of producer-gas power plants. Government inquiries during the past eight years not only have shown a very low fuel consumption per horsepower-hour for these plants but have demonstrated conclusively the possibility of utilizing commer- cially low grades of bituminous coal, lignite, and peat in plants prop- erly designed for the use of these fuels. The anthracite plant has been recognized as a commercial possibility for several years, although the cost of the fuel used has in general restricted these plants to com- paratively small units. The commercial development of the producer-gas power plant in the United States has been largely within the past six or eight years. In 1909 the United States Geological Survey published in a bulletin entitled "Recent Development of the Producer-Gas Power Plant in the United States" a list of producer-gas power-plant installations. The data presented in that bulletin showed a strong development in this field and led to much conjecture as to the future of this type of power. Owing to the extensive introduction of the steam turbine, however, many persons predicted the almost immediate doom of the producer-gas plant. In addition to the inroads made by this formida- ble rival, the interest of the gas-engine enthusiasts became centered to such an extent in the oil engine that the gas producer was relegated to second place by many and absolutely abandoned by some. During the past three years the belief of many who were formerly firm be- lievers in the gas producer has been that this type of power has reached its height of development in this country and that from a commercial standpoint it can no longer be regarded as a complete success. This feeling of commercial decadence has become so general

Jan 1, 1913

By E. Morrice

Techniques developed by the Bureau of Mines for the preparation of high-purity rare-earth metals and their alloys by electrolysis of the oxides in fluoride media are summarized. Cerium, lanthanum, neodymium, praseodymium, dysprosium, gadolinium, and yttrium metals, the mixture didymium, and specific alloys of these metals and samarium with iron, nickel, chromium, and cobalt were prepared. Individual metals were electrodeposited in the liquid state on tungsten or molybdenum cathodes. Alloys were prepared by electrodepositing the rare-earth metal on a consumable cathode, at a temperature above the melting point of the eutectic formed between the rare-earth element and the cathode material. Cells were designed for electrowinning metal products in gram and pound quantities, and methods for continuous electrowinning of cerium and lanthanum were developed.

Jan 1, 1968

By L. Garner McDonald

The U.S. Bureau of Mines tangentially impacted potential coal-cutter bit shank materials against sandstone to investigate the potential of the materials to ignite natural gas by a friction-generated hot streak. The shank material samples were mounted in a 24-in, 550-lb flywheel, which was rotated at surface speeds of 400 to 900 sfpm. The sandstone was advanced toward the rotating flywheel at feed rates of 1 mil per impact. The atmosphere mixture was 7 vol pet natural gas in air. Three grades of polycarbonate resin, an ultra-high-molecular weight polyethylene, and a zinc alloy (ZA27) were among the potential materials. None of these materials caused ignition of the methane at any of the three test speeds (400, 600, and 900 sfpm), but the above materials do not have sufficient strength to hold a carbide tip during coal cutting. Of the materials having sufficient strength to hold a carbide tip, three nickel-based alloys proved less likely to cause a natural gas ignition than did iron-based alloys such as 4340 (a commonly used shank material for coal cutters).

Jan 1, 1992

By Douglas C. Peters, Valois R. Shea-Albin, Dennis R. Dolinar

An accurate assessment of the vertical stress on a coal seam at depth is important for mine design. Vertical stress calculation techniques presently available either are not sufficiently accurate or cannot handle complex surface topography. Therefore, the U.S. Bureau of Mines developed a computerized method to calculate vertical stress exerted on surfaces at depth that includes the effect of topography. Two input data sets are required: a digital elevation model containing topographic elevations and a coal seam file defining coal seam elevations at depth. Boussinesq's equation then quantifies the vertical stress resulting from topography. The computerized method was tested on a coal seam overlain by a complex topography where a vertical stress map encompassing several square miles was produced. Results show that depth mitigates the affects of surface topography, while the coal seam topography has a direct effect on the vertical stress. In comparison to the computerized method, the direct stress method overestimates stress under hills and underestimates stress under valleys. The largest difference between the two methods occurs under the steepest topographic relief. A limitation of the computerized method is that stresses cannot be accurately determined near an outcrop.

Jan 1, 1992

By C. H. Herty

Intensive work on the deoxidation of steel with manganese-silicon alloys by the U. S. Bureau of Mines has shown that the use of those alloys, which may be produced from our domestic manganese ores, would decrease the ferromanganese requirements of a very large tone of our steel by from 60 to 30 per cent and in some cases by 100 per cent. The open-hearth heats made with these alloys have been of excellent quality. The tonnage of our ferro-grade ores which has been made available by the bureau's ore-dressing studies, combined with the ,products resulting from such processes as those developed by the bureau and by Bradley for Cuyuna ores, should easily fill our reduced ferromanganese requirements Then manganese-silicon alloys and ordinary spiegel are used in the way described in this report. There are no technical difficulties in the application of this practice, and any difficulties involved in its wide and immediate application would only be those arising from habituated ideas of the necessity of ferromangenese. General acceptance of this practice and development of the available sources of domestic ferro-grade material by already proven processes should make this country independent of foreign ores.

Jan 1, 1931

By James P. Ulery, Stephen J. Kravits, William P. Diamond

This report presents results of a cooperative research project between the U.S. Bureau of Mines and Beth Energy Mines, Inc. Four coreholes (two before mining and two after mining) were drilled at a longwall mine operating in the Lower Kittanning Coalbed to obtain coal and rock samples from overlying strata to determine their gas content at various times in the mining cycle. The results of those tests indicate that 91 pct of the gas removed from the overlying strata came from coalbeds. Material balance calculations were made to compare the volume of gas produced both from gob gas vent holes drilled on the panel and gas removed by the mine's ventilation system with the volume of gas removed from strata directly overlying the panel to a height of 275 ft. This analysis indicates that only 40 pct of the total gas produced from the panel actually came from the strata directly overlying the panel. The remaining volume of gas production probably migrated to the Iongwall gob from overlying, and perhaps underlying, strata immediately adjacent to the panel and perhaps from greater distances downdip because of the establishment of a long-term pressure gradient in the study area.

Jan 1, 1992

By Jürgen F. PH. D. Brune, Alex C. Smith, Michael A. Trevits

Underground coal mine fires in the United States continue to present a significant hazard to the safety and health of mine workers. The leading causes of mine fires include flame cutting and welding operations, frictional heating and ignitions, electrical shorts, mobile equipment malfunctions, and spontaneous combustion The National Institute for Occupational Safety and Health (NIOSH) is conducting an in-depth program of research to address mine fire prevention, early and reliable fire detection and mine fire suppression and control technologies. One segment of the research portfolio is focused on remote methods for addressing coal mine fires. This research is important because remote methods represent the primary means of fighting a mine fire when conditions are too dangerous to fight the fire directly underground. Technologies under investigation include remote methods for installing ventilation control devices (mine fire seals) and remote methods for suppressing the fire using, the injection of inert gas, gas-enhanced foam and jet engine exhaust gases into the fire zone. This paper presents a summary of remote mine firefighting technologies used in the U.S. and the results of completed NIOSH research.

By Gregory J. Chekan

In order to reduce waste and improve resource conservation, mine planning, and development, the U.S. Bureau of Mines is investigating multiple seam interactions associated with longwall mining. Longwall gate entry and panel stability have been influenced by previous mining in coalbeds above and below a mine in Virginia that operates in the Lower Banner Coalbed. Directly superjacent, approximately 115 ft, the Upper Banner Coalbed has been partially worked by room-and-pillar mining. Directly subjacent, approximately 730 ft, the Tiller Coalbed has been worked by partial room-and-pillar retreat mining. The study mine has experienced problems during development of gate entries in areas of overmining and undermining. It is anticipated that stress fields associated with adjacent mining may further affect gate entry stability and face advancement during the extraction of the longwall panel. To assess overmining and undermining effects on ground stability, the Bureau gathered geotechnical information at the site. Headgate entries and pillars were instrumented and monitored to study loading behavior as the longwall face approached and passed potential problem areas. Measurements indicate that although increases in average pillar pressure were greater than predicted values, previous mining in adjacent coalbeds had little effect on headgate stability.

Jan 1, 1989

By T. R. Taubert, D. H. Carlson, J. H. Johnson

The U.S. Bureau of Mines and Michigan Technological University (MTU) are collaborating to develop an apparatus for measuring diesel tailpipe emissions in underground mines. A tailpipe emissions measurement apparatus (EMA) is described that dilutes diesel exhaust and measures the concentrations of diesel particulate matter (DPM), CO, CO, NO, and NO, at known dilution ratios. The EMA was evaluated by side-by-side comparison of its measurements with those by laboratory- grade instruments. Concentrations of CO and CO, measured by the EMA were usually within + 14 pct of concentrations measured by laboratory-grade instruments for CO and 220 pct for CO,. EMA- measured DPM concentrations were, on average, 29 pct lower than those measured by laboratory-grade instruments, with the differences being fairly consistent. The CO and CO, differences are related to the method of calculating the EMA's dilution ratio, and the difference in DPM concentrations is attributed to thermophoretic and/or condensation losses related to the EMA's unheated sample probe. Preliminary analysis of data obtained with a heated sampling probe and modifications in the sampling procedures have indicated reduced variability in DPM and in the calculated dilution ratios.

Jan 1, 1992

Determine the extent of upper extremity cumulative trauma disorders (UECTD's) in the U.S. mining industry. Background UECTD's are injuries that develop gradually over a period of time as a result of repeated stress to a particular body part without adequate time between stresses for full recovery to occur. The stresses that contribute to UECTD's may occur because of the following work components: awkward position of wrist or arm, excessive manual force, high repetitions of manual movement and effort, cold environment, and vibration. Cumulative trauma injuries to the arm and hand have become an ever growing concern among safety and health professionals in a number of different industries and work settings, such as meatpacking operations, assembly-line work, and keyboarding. Mine workers arc also exposed to a combination of stressors and work design deficiencies that result in arm and hand injuries. For example, certain job tasks and environments, such as that of an underground jackleg driller, expose miners to segmental (hand-arm) vibration and cold temperatures. Operators of underground mobile equipment, such as scoops and trams, regularly have their hands in direct contact with vibrating levers and controls.

Jan 1, 1992

By Blair Burwell

This paper describing the method of mining a deposit of vanadium ore near Rifle, Colo., is one of a series of similar papers on metal-mining methods and costs being issued by the United States Bureau of Mines. This vanadium deposit probably is the largest yet found in North America. It is situated 12 miles northeast of Rifle, Colo. (see fig. 1), on the southern flank of tae White River plateau, and is at an altitude of 6,500 feet. Between 150 and 200 tons of ore are mined daily and trucked to the mill at Rifle. The product of the mill is fined vanadium oxide, which is shipped to the company's plaits at Columbiana, Ohio, and Niagara Falls, N. Y., for the electric manufacture of ferrovanadium. HISTORY The deposit was discovered about 1909 by men prospecting for carnotite. Its outcrop on the bola cliff of Rifle Canon had been known to stockmen for many years.

Jan 1, 1932

By J. M. Stuve

Calorimetric data for the dissolution of scandium sesquioxide and scandium trichloride in 4.360 molal hydrochloric acid were used to evaluate the standard heat of formation of ScCl3(c). The heat of reaction for Sc(c) + 1.5Cl2(g) = ScCl3(c) at 298.15° K was computed as -225,440 ±340 cal/mole.

Jan 1, 1965