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By A. B. Hooker

All state mining laws require that flame safety lamps be used in gassy mines; the laws of some States require that safety lamps be kept for emergencies at every coal mine, whether gassy or nongassy. The use of the flame safety lamp has been widespread because it is the only defice readily available for detecting both the presence of methane and deficiency of oxygen. This paper reports the results of an investigation by the Electrical Section, in cooperation with the Gas Section, of the Pittsburgh Experiment station relative to the behavior of permissible flame Safety lamps in mine atmospheres deficient in oxygen and the effects of methan5/ on the detection of oxygen deficiency.

Jan 1, 1937

By Elton L. Litchfield

The techniques for direct initiation of detonation, developed by the Bureau of Mines, have been applied to gaseous mixtures of oxygen with methane, 'thane, propane, butane, or hexane. An exploding wire was used as the initiation source to determine minimum stored electrical energies required to effect detonation of mixtures between one-half and two times the stoichiometric fuel ratios. Detonations were obtained in the most easily initiated mixtures of ethane, propane, butane, and hexane for initiation energies between 24 and 33 joules at 1 atm and 28-43 joules at 0.5 atm initial pressure. Methane mixtures, at 1 atm, were not observed to detonate when initiated with up to 484 joules.

Jan 1, 1966

Objective To accurately measure very low air velocities (0-100 ft/min) in U.S. large-opening underground metal/nonmetal mines. Background Hundreds of metal/nonmetal underground mines operate throughout the United States. They extract commercial products from deposits such as limestone, salt, and gypsum. Mining generates a wide variety of gases and dusts, such as silica, diesel exhaust, radon, blasting byproducts, and perhaps even methane. If these substances become airborne, they can adversely affect the health and safety of underground workers. Many metal/nonmetal mines have large cross-sectional airways that could be 60 times larger than an average underground coal mine entry. These large airways require adequate volumes of fresh air to dilute, make harmless, and exhaust the toxic and, at times, explosive byproducts. However, in some underground mine sections, air movement is barely perceptible. The technology of measuring very low air velocities will become increasingly more important for operators of large-opening stone mines in order to monitor miner exposure to diesel particulate matter. Conventional anemometers (e.g., vane) are capable of accurately measuring air velocities only above 100 ft/min. Thus, it was necessary to investigate other anemometry technology to detect low air velocities in the range of 0-100 ft/min. Two different portable ultrasonic anemometers were tested. Actual testing was done in an underground limestone mine with openings about 51 ft wide by 29 ft high. Ultrasonic Anemometers Vane-type anemometers are commonly used by engineering personnel throughout the underground coal mine industry. They work well in measuring air velocities >100 ft/min. However, a separate technology, e.g., portable ultrasonics, is needed to measure air velocities much below 100 ft/min at various places within the large mine opening. Laser-doppler technology was also considered for this application, but was ruled out because of its high cost and other technical limitations. With no moving parts, the portable ultrasonic anemometers are claimed to be accurate down to about 1or 2 ft/min. The first type of ultrasonic anemometer that was examined underground is manufactured by Gill Instruments Ltd., Hampshire, U.K. The U.S. distributor is IN USA, Needham, MA. The Gill Instruments Solent Volometer (figure 1) is a battery-powered, single-axis anemometer meant for measuring low to medium air flows up to1,999 ft/min. It uses the ultrasonic "time of flight" principle where pulses of high-frequency sound are transmitted along the air flow path and the time taken to reach the receiver is measured. The faster the air speed, the quicker the pulses reach the receiver. The second ultrasonic anemometer that was examined under-ground is manufactured by Airflow Developments Ltd., Buckinghamshire, U.K. The U.S. distributor is Airflow Technical Products, Inc., Andover, NJ. The Anemosonic UA-6 (figure 2) is a battery-powered, handheld instrument with digital display. It measures air velocity (0 to 9,999 ft/min) or volume flow, flow turbulence intensity, and air temperature. Neither device is considered to be intrinsically safe for use in underground gassy coal mines. A comparison of salient specifications of both instruments is shown in table 1. The total suspended weight includes the instrument (Gill) or instrument probe (Airflow) plus about 35 ft of connecting cable attached to the pole. This combination of instrument plus cable length allows two operators to measure air velocities up to about 30 ft above the mine floor. Figures 1 and 2 show how each unit would be attached to an extensible, graduated fiberglass rod in order to position the sensor probe at a certain spatial point (centroid of the quadrate) within the underground large opening.

Jan 1, 2003

By R. Karl Zipf, Christopher Mark

Highwall mining continues to grow in importance as a coal production method from U.S. surface mines. It may account for as much as 4% of the total U.S. coal production, according to one recent estimate. Analysis of Mine Safety and Health Administration (MSHA) accident and injury statistics shows that, overall, highwall mining has maintained an admirable safety record. Its fatality and injury rates are comparable to those for other surface mining methods, and are significantly lower than those for underground mining. No mining method is risk free, however. Highwall mining injuries have been associated with handling materials, slips and falls, machinery, powered haulage, and other types of incidents. But perhaps the greatest risk, to both personnel and equipment, is from ground control. The two most significant ground control hazards are rock falls from the highwall and equipment entrapment underground. Highwall Stability Ensuring highwall stability through proper ground control engineering is of paramount importance to safe highwall mining operations. The only fatality to occur during the last five years at a highwall mining operation was due to highwall collapse. There have also been numerous near-misses, several of which have involved extensive damage to equipment. In the central Appalachians, where the majority of highwall mining occurs in the U.S., hillseams are the most prominent geologic structures that affect highwall stability. Hillseams (or mountain cracks) are near vertical fractures in the rock that are formed in response to natural weathering and erosion of hillsides. They extend hundreds of feet down from the surface. They typically run parallel to the hillside, but they can also extend across narrow points or ridge lines. The hazard arises when rock slabs that form along the hillseams detach and fall away from the highwall face (See Figure 1). [ ] Unfortunately, it is impossible to control the location of hillseams or reliably detect their presence within a highwall. There are, however, a number of measures that can be taken to minimize the risk of failure associated with hillseams: Planning-Most operators choose to skip those areas of the highwall where a prominent hillseam daylights (See Figure 2). Existence of such areas is known for several weeks in advance of highwall mining; therefore, planning engineers can adjust the layout of highwall mining panels to locate barrier pillars within areas of questionable highwall stability. [ ] Inspection and monitoring-Daily inspection of the benches above the active highwall mining area is a prudent precautionary measure. A crack in a bench immediately above a highwall miner is shown in Figure 3. Simple displacement monitors may be useful for detecting movement along cracks that may precede a significant life-threatening failure. New tools, such as slope monitoring radar, may also prove useful in detecting motion of the rock slopes above active highwall mining operations. Good blasting practice-Most surface coal miners in the central Appalachians use pre-splitting and the familiar halfbarrels are routinely seen throughout the pits. Shorter delays along the face and longer delays between rows can direct more of the blast force parallel to the face, potentially doing less damage to the wall rock. In addition to pre-splitting, decreasing the burden, spacing and charge weight in drill holes close to the highwall will also decrease damage to the wall rock. Decreasing the highwall slope angle-Decreasing the highwall slope angle from 90° (vertical) to 70°-80°, especially in areas of known hillseam concentration, could eliminate the hillseam hazard (See Figure 4). Angled highwalls are routinely employed in many Midwestern surface mines and in some

By C. Travis Anderson

"A recent critical study by Ralston3 of the iron system points out the importance of and necessity for work upon the preparation of ferrous oxide. Not only are ferrous oxide samples desired for determination of the important physical and chemical properties, such as specific heats and heats of formation, bat also information on the stability and behavior of this material is of considerable technical importance. Related. problems where the properties of Fe0 are important have to do with desulphurization of iron, the formation and occurrence of magnetite in copper smelter slags, and sulphur elimination in copperFerrous oxide also has valuable catalytic properties, as is demonstrated in nitrogen fixation.Pure ferrous oxide has never been prepared in quantities large enough to furnish adequate physical and chemical data on its properties. Only two or three experiments4 have produced a fraction of a gram in a state approximating purity and have collected evidence that has been sufficient proof of their having done so. Ferrous oxide is stable only above about 570°C., and below that splits into magnetite and iron according to the reactionUp to about 1920, those who had endeavored to prepare FeO made no provision for rapid chilling, so that although their product. may have had the proper iron oxygen ratio for FeO, in reality it-probably did not consist of pure FeO. The above reaction is reversible; above 570oC. magnetite and iron are supposed to recombine almost completely, and if so, should constitute a direct and easy method of preparation. The data, however, were somewhat conflicting, and the extent to which the reaction goes in either direction needed checking. Preliminary experiments on the interaction of molten Fe304 with solid Fe gave Fe0 of about 85 per cent purity, corresponding to. the approximate purity obtained by some previous investigators. The present work is concerned chiefly with the results cf repeated interaction between partly reduced magnetite and iron, and the calculations which may be made from such results. Repeated treatments are necessary, because molten impure ferrous oxide and iron can not be kept in contact for more than short periods of time."

Oct 1, 1928

By J. B. Janus

This report continues a series of analyses of coal samples made by the Bureau of Mines in connection with the yearly purchase of several million tons of coal for various Government agencies. Listed are the analytical data on the composition and quality of tipple and de livered samples of coal collected during fiscal year 1974.

Jan 1, 1975

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

In December's marketing of 99.5 percent aluminum ingot, domestic producer pricing remained at 53$ per pound, while dealer quoting rose from 47.5¢ to 48.5¢. BORON Domestic production of boron minerals and chemicals reached an all-time high in 1977--1.4 million short tons valued at $236 million. Combined sales of the three California producers topped the 1976 level by 15 percent in quantity and 28 percent in value, a consequence of healthy demand in the glass and insulation industries. Unprecedented demand for boric acid as a flame retardant for cellulosic insulation stimulated producers to utilize fully all available capacity, thereby achieving a record output of 158,000 tons. One company increased output from its existing boric acid facilities and initiated production at another plant that historically had produced only sodium borates. A second company achieved a previously planned 25 percent plant expansion.

Jan 1, 1978

By H. W. Wainwright

One phase of the research and development work on synthetic liquid fuels conducted by the Bureau of Mines at Morgantown, W. Va. in cooperation with West Virginia University deals with the purification of synthesis gas.2/ Most of the experimental studies on gas purification have been directed toward the removal of organic sulfur from gas, either catalytically or by adsorption with activated carbon. An important part of the purification program has been the development of suitable analytical methods for determining organic sulfur compounds. As the total sulfur content, organic and inorganic, of purified synthesis gas should not exceed 0.1 grain per 100 cubic feet, the need for accurate analytical methods is apparent. It is also apparent that such methods must be rapid if one wishes to evaluate various processes for removing sulfur from gas. The organic sulfur found in most gas produced from coal is usually present as carbon disulfide, carbon oxysulfide, methyl and ethyl mercaptans, and thiophene, with the exception of thiophene, the remaining organic sulfur compounds respond similarly to catalytic treatment and can be removed effectively. Not only does thiophene resist most catalytic treatment, but it poisons some catalysts, rendering them ineffective in removing the other forms of organic sulfur.

Jan 1, 1950

1. In 2002, a total of 2,065 coal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Coal mines comprised 14.2% of all mining operations. • Bituminous mines comprised 92.5% (n = 1,910) and anthracite mines 7.5% (n = 155) of coal mining operations. • More than 70% of all coal mines were located in three states: Kentucky (28.7%), West Virginia (21.7%), and Pennsylvania (20.1%).

Jan 1, 2004

By Murray Jacobson

The respirable dust standard in the Federal Coal Mine Health and Safety Act of 1969 is designed to prevent disability and death from coal workers' pneumoconiosis. Beginning June 30, 1970, the operators of coal mines were required to maintain the average concentration of respirable dust in the active workings at or below 3.0 milligrams of dust per cubic meter of air. The standard is reduced to 2.0 milligrams per cubic meter after Dec. 30, 1972. This paper presents the equipment and procedures used by the coal mine operators in implementing the respirable dust sampling program established by the Secretary of the Interior and the Secretary of Health, Education, and Welfare and shows the effect of the law, during the first year, on the reduction of dust levels in selected mines. The system employed by the Bureau of Mines for analyzing and processing the dust samples is also presented.

Jan 1, 1971

By L. B. Pankratz

Enthalpies above 298° K were investigated for four crystalline sodium borates by copper-block drop calorimetry. Determinations were made to 1,200° K for NaB02, 1,003° K for Na2B407, 1,005° K for NaB305, and 1,046° K for Na2Be013. No phase transitions or other thermal anomalies were found. The enthalpy determinations, when combined with known heats of formation at 298° K and other supplementary data, enabled the calculation of the heats and free energies of formation of the compounds to their melting points. Values of relative enthalpies, entropies, heat capacities, free energy functions, enthalpies of formation, free energies of formation, and equilibrium constants of formation were tabulated at even temperatures.

Jan 1, 1971

By Hylton R. Brown

Advertisements and articles in technical and trade journals announce the approach of a new age, in which plastics, light metals, laminated wood, and numerous other products or byproducts will be used in the construction of automobiles, airplanes, and furniture and equipment used in our factories, offices, and homes. Undoubtedly, after the war there will be many such developments which will introduce new manufacturing methods and new hazards to challenge the safety engineer. Already we know, from experience in laboratories and pilot plants where these new products are being tested, that there will be many fire and explosion hazards to be overcome. The danger of dust explosions may be one of the principal hazards, because thetic resins and other materials used in the plastics industry, as well as metal powders, wood dust, and other finely divided substances, are capable of forming explosive mixtures in air. Heavy losses of life and property have been caused by dust explosions in flour and feed mills, starch factories, and grain elevators, and it will be well to consider the possibilities that such losses may occur in any new industry and to provide all possible safeguards against hazards. Fortunately, we have learned something about the behavior of dust explosions and know something about the ease of ignition, limits of Explosive concentration, end pressure developed. Our efforts should now be directed toward the application of this knowledge in the development of safe operating practices.

Jan 1, 1945

By S. P. Signer

The Bureau of Mines conducted a series of field tests to improve the understanding of the support interaction mechanics between fully grouted bolts and coal mine roofs and to help lay the foundation for improved design and evaluation techniques. Strain gauges were installed on 14 fully grouted bolts placed in shale roof rock at four mines in Colorado, Illinois, and Pennsylvania to determine how load was transferred between the bolts and the rock. The results of field tests on elastic bolt behavior compared well with previous laboratory work and numerical models. The field tests showed that the anchorage length of grouted bolts installed in shale was slightly longer than the anchorage length determined in laboratory tests conducted in concrete blocks. The field results produced more variability because of geological variations. Tests run past the yield point of the steel bolt indicate that the yield zone varies significantly and translates down the length of the bolt anywhere from 4 to 22 in.

Jan 1, 1990

By F. F. Hintze

In the group of minerals used in making this study, the cyanite is associated with quartz, mica, and feldspar in the schist. The amount of quartz is variable, but it is always an abundant mineral. Both large and small crystals of quartz occur in irregular masses, rarely ever showing crystal outline. Mica is of the clear and dark varieties, the larger crystals being dark as a rule, and the finer crystals of light color. The present mineralogical composition of the mina is rather variable, as most of the original biotite and muscovite have suffered alteration, and much secondary mioa is present as a result of alteration of the original mica and other minerals present, especially the larger cyanite crystals. A large part of the mica now found in the ore is chlorite, with varying amounts of Jefferisite and others, especially sericite. These are in the form of aggregates, or felt-like intergrowths filling the spaces between the quartz, cyanite, and feldspar.

Jan 1, 1931

By Jerry W. Ramsey

The Bureau of Mines studied two Pennsylvania anthracites using low-temperature carbon dioxide adsorption. A modified form of the Brunauer-Emmett-Teller equation was used to calculate specific surface areas. Two mesh sizes of each anthracite were used to determine how gamma irradiation at 106 and 108 rads, both in vacuum and in the presence of air, affected the carbon dioxide surface areas. Results show that anthracites have a system of pores that are essentially all interconnected rather than isolated; that anthracites differ from one another in specific surface, which may correlate with density; and that irradiation in vacuum has no discernible effect on specific surface of anthracite, but irradiation in air does produce changes in specific surface.

Jan 1, 1966

By Larmon J. Heath

The Bureau of Mines explored the use of air or natural gas for recovering additional oil from natural water-drive reservoirs with little or no original gas saturation. Engineering and production data for a field in the Mid-Continent area, results of limited laboratory experiments, and data shown in the literature were considered. Injecting air into a water-coned well could seriously damage the well. Injecting natural gas into the watered-out zone could improve the producing water-oil ratio. In the reservoir studied, oil recovery can be increased by injecting natural gas to decrease water-oil ratios. Laboratory tests on a core from the field show an increase in oil recovery of 7.6 percent of the original oil in place as a result of increasing the free gas saturation. This recovery could amount to as much as an additional 6 million barrels of oil from this field.

Jan 1, 1966

By R. Pakalnis, Richard P. Curtin, Lewis A. Martin

Instrumented cable bolts developed at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health were used in conjunction with existing ground control to monitor rock mass loads at various field sites (T.G. Soda Ash, Getchell, Meikle, SSX, K-2, and Stillwater). Axial and shear loads were determined by strain gages to levels of instrument accuracy of ±5 N or ±5 microstrain as these loads were transferred to the instrumented cable bolts. These gages were 12.5 mm long and embedded into a remanufactured king wire that replaced the conventional king wire. Cable bolt performance, quality of grout, and installation techniques were also assessed. By using instrumented cables, a mine operator can determine axial load along the cable at predefined gage locations. By monitoring load on and displacement of the rock mass, more effective ground support can be selected and installed, which will lead to safer working conditions for miners.

By Wilbur I. Duvall

This report presents experimental data on the propagation of explosion- generated strain pulses in rock. Tests were performed in 5 different rock types, employing 10 different types of explosives. Charge sizes ranged from 0.5 to 50 pounds, and travel distances ranged from 2.5 to 70 feet. Analysis of the data shows that the experimental peak strain data satisfy an exponential decay propagation law of the form: ?R/W1/3 = Ke ?aR/W1/3. For a particular rock, parameter K is a linear function of the calculated detonation pressure or the calculated energy density of the explosive. For a particular explosive, K is a linear function of the elastic parameter of the rock, p2, a result, which is at variance with elastic theory. The absorption constant, a, is independent of type of explosive but dependent upon rock type. However, no definite relation between a and the physical properties of the rock could be established.

Jan 1, 1959

By A. M. Cummings

During August 1943, the Bureau of Mines undertook sampling and measuring of the Kennedy zinc tailing pile near Hazel Green, Lafayette County, south-western Wisconsin, as part of a general investigation of this lead-and zinc-producing area at a time when it was extremely important to increase the production of metals for the Nation's War program. The tailing pile was the residue from old jigging plants that treated ore from the Kennedy mine, one of the oldest and. largest mines in the district. Because retreatment of tailing by modern milling methods was proving economically successful at other sites in the southwestern Wisconsin field, the Bureau?s investigation was designed to assist the potential operators in evaluating the feasibility of a retreatment operation at this site. The study involved measurement of the tailing pile and sampling by means of auger to determine the average metal content within the narrowest possible limits. A total of 46 auger holes ranging in depths up to 40 feet and aggregating 886.5 feet of bore were drilled in the tailing pile, and weighted samples from each hole were analyzed and averaged to determine the zinc and iron content of the tailing.

Jan 1, 1949