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By S. L. Gerhard

In the United States the performance characteristics of permissible explosives are controlled by routine tests, which include firing the explosive into a gallery filled with a methane-air mixture. These tests are made by the staff of the Explosives Division of the Bureau of Mines and, are similar, in general, to those employed in other countries. This control has helped to reduce the frequency of accidents involving the ignition of firedamp by explosives but has not clarified the basic causes, of the ignition. To advance this control and to minimize potential hazards further, this fundamental knowledge is needed. Some of the results of recent research on the causes of the ignition are described herein. NATURE OF THE PROBLEM When an explosive ignites firedamp in the gallery tests, the source of the ignition must be one or more of the emissions from the steel borehole. It has been accepted generally that these emissions are (1) particles, (2) the shock wave, and (3) hot gases and flames. Photographs show that the shock wave emerges from the borehole first, followed closely by hot gases. At first the velocities of these are high and approximately equal, but the velocity of the gases decreases more' rapidly than that of the shock wave, and by the time the reactions causing the flame are complete the shock wave travels in an otherwise undisturbed medium. The particles are originally enveloped in the hot gases but some soon begin to break through and eventually out-distance the shock wave. The approximate geometry of these emissions about I millisecond after the shpt is fired is illustrated in figure

Jan 1, 1939

By F. G. Miller

[Petroleum tscknologists nnd progressive operatorr. constantly are striving to increase the percentage of oil thnt may be recorered from reservoir rocks through wells. The exhaustive studies that hve boen made of the function of natural gas in the production of oil, for example, havo aided operators greatly in increasing tho quantity of oil recovered from reservoirs. Natural gas dissolv.3d in and otheraiso asnociatod under pressuro with oil in rsservoir rocks, howovor, is not tho only source of energy available for rnovi~~ oil through sands to wells. In becomine Veservoi~enorgy conscious^^ encineera havo lonrned that in nnny petroleum resorroirs the edgewater flanking the oil accurrulation constitutos a potantinl source of enorgy cnpnblo, through pro1,sr control, of increasing oil-recovory officioncies materially. ?To longer is tho oncronchmont of mter into the oil- and gas-fillod uart of tho reservoir conridsred as evil to be combatted by dovious mothods but rnthar a nrtturrtl consequence, incident to the withdraval of oil nna gas from tho rolls, thnt mP.y be used nd~~mtngeoualy in lengthening the flowing life of wells ,md incre~sing the oconornic recovery nf oil and gns. Little is knom a3out tho nac'n-~nisrn by mhich wnter qor-rtos in driving nil through reservoir rocks, nnd thjro is n scnrcity of published informa- tion on rates of rnovzrnant of ~ntcr +,hat will result in naxilnm oil recoveries. Bureau of Xine s er.gir.ess nr r'reciate the ~aucity of scientific knowledge on the best methods of lying the natural rater drive to in- crease oil-recovery efficiencies arid ar9 initiating stildies that rill, they hope, contributo to tho procont small fund of information now available on the subject. This rh~.ort is s syr,o_nsis or brief c03pilation of published dAta and thought nccumulntod 30 far, groliminary to la-uorgtory ox~eriment+ tion NI& further resaarch on the principlgs und~rlying the nnturnl wnter drive RS it nffocts oil rocovory. The vrritors hopo th2t the omosition of available information prosentod in tho rey~ort rill stindate constructive thought and efforts loading torard moro comrlote extraction of oil and gas from resorvoirs.]

Jan 1, 1938

By Michael J. Beus

This Bureau of Mines report describes the development of load cells for measuring compressive loads in timber and lock-bolt support systems commonly used in. coal; metal, and nonmetal mines Design and evaluation is covered in detail to insure a reliable, accurate, and practical instrumentation scheme. The load cells are relatively inexpensive and adaptable to various size support systems. User-oriented procedures are emphasized, and design equations were reduced to a series of nomographs. Laboratory evaluation, destructive testing, environmental testing, and tests to determine the effect of extraneous loads were conducted. Field performance was evaluated in conjunction with ongoing Bureau projects at a metal mine in North Idaho and a coal mine in Utah. Load cells utilizing a titanium alloy as the cell body and weldable strain gages as the strain-sensing components satisfied the basic design and performance criteria, and with minor design modifications, the load cells can be adapted to many mining applications.

Jan 1, 1974

By G. S. Scott

[In the course of the investigation the Bureau of Mines is carrying on to determine the causes, behavior, and control of mine fires, the detection of incipient heating underground in the mines and above ground in refuse banks has received consideration. A report has been published5/ describing apparatus and tests made on anthracite to determine the amount and composition of the a oxidation products when normal dry air was passed through it at temperatures varrying from 100° to 350° C. These tests showed that the amount of evolved gases and their relative proportions varied with the temperature. From these results, graphs were prepared by which the temperature at which the coal was oxidized could be estimated thus giving a possible means of detecting incipient heating.]

Jan 1, 1938

By L. A. Haas

The Bureau of Mines conducted bench-scale leaching tests with recycled spent copper electrolytes and copper-nickel mattes produced from the Minnesota Duluth Complex concentrates. This report describes the first stage of an overall two-stage leach operation. The objective of this research was to determine the matte-leach technology required to convert spent copper electrolyte into an enriched nickel liquor suitable for a nickel refinery and there-fore essentially free of copper, iron, and sulfuric acid. The experimental variables investigated were matte composition, particle size, spent electrolyte content, pulp concentration, oxygenation, temperature, and time. The time required to produce an enriched purified nickel liquor decreased with increasing pulp concentration, temperature, and oxygenation, but increased with increasing particle size and electrolyte copper and acid content. Nickel-rich (about 50 g/l) liquors at a pH of about 4 and containing less than 1 g/l of copper and iron were produced at 70° C by leaching minus 325-mesh low-iron (less than 5 pct) matte for 8 hours with spent electrolyte containing 22.4 g/l Cu, 28.9 g/l Ni, less than 0.1 g/l Fe, and 50 g/l H2S04 at a pulp concentration of 1 kg of matte per liter of spent electrolyteo Varying the nickel content of the spent electrolyte from 11 to 101 g/l appeared to have no appreciable influence on the matte leaching characteristics.

Jan 1, 1981

By Foster Fraas

This Bureau of Mines report describes a method for separating minerals at magnetic susceptibilities within the diamagnetic susceptibility range. The maximum feed rate varies directly with the square root of the lower limit of permissible susceptibility, while the lower limit of permissible susceptibility varies inversely as the square of the magnetic field strength. Minerals may be separated at particle sizes smaller than possible on conventional dry-type magnetic separators.

Jan 1, 1969

By G. M. Potter

During the investigation of the occurrence of manganese deposits in the western United States, examining engineers of the Bureau of Mines collected samples from four properties in Siskiyou and Mendocino Counties northern California. As the ores were too low-grade to be acceptable to manufacturers of ferromanganese, beneficiation studies were made between 1941 and 1945 to determine the amenability of the ores to concentration. The Johnson and Reynolds properties are near Fort Jones Siskiyou County. The ore occurs in a number of small lenses in that area. Samples were taken for testing for amenability to treatment in a small custom-gravity plant, tentatively planned. by the Waiter Johnson interests of San Francisco. A 2-ton representative sample was obtained from numerous exposed portions of an outcrop on the property of the Mayland Mining Co. The Mayland mine is about 8 miles from Sawyers Bar in Siskiyou County. The ore body consists of stringers and irregular masses of oxide, and. silicate ore scattered through quartz, which these minerals have replaced.

Jan 1, 1952

By Alex C. Smith, Thomas A. Gray, Lynn M. Crayne, Michael A. Trevits, Phil Glogowski

Mine fires constitute one of the greatest threats to the health and safety of those working in the underground environment and each event has the potential for disastrous consequences. Of the major mine fires and thermal events that have occurred in the United States in the last 6 years, it is estimated that remotely installed seals could have been used in 63% of the events to control fire growth or to aid in fire suppression work. The National Institute for Occupational Safety and Health (NIOSH) is conducting full-scale tests at the NIOSH Lake Lynn Experimental Mine to evaluate and improve remote mine seal construction technology. The main focus of this work is to develop reliable technology that will completely close the mine opening from floor-to-roof and rib-to-rib. This paper presents the results of remote seal installations using grout-based materials.

By J. A. Lamonica

The Bureau of Mines studied two types of approved coal mine dust personal samplers to determine the effect of decreasing the amplitude of airflow velocity fluctuations on cyclone performance. Results indicate that more dust is collected when pulsation free flow is used. Velocity fluctuations were reduced by means of a pulsation damper; damper efficiency of about 85 percent was needed to reduce the fluctuations to an acceptable level. The data were obtained employing both pulsating and non-pulsating flow. A comparison was made of (1) the masses of respirable coal dust as determined by weighing and of (2) the particle size distributions as determined by an electronic counter. An empirical relationship is given between the ratio of masses collected using pulsating and nonpulsating flow (M') and the ratio of the maximum air velocity to the minimum air velocity (V') as measured in the cyclone entrance channel.

Jan 1, 1972

By E. P. Hayes

This report supplements the date contained in Bureau of Mines Information Circular 6156, "Special features of core drilling in the salt beds of Western Texas and New Mexico," by J. S. Wroth. That circular dealt with the drilling of the first 12 of the 24 potash tests made by the U. S. Bureau of Mines in cooperation with the U. S. Geological Survey; this report is concerned with the drilling of the last 12 tests. ACKNOWLEDGMENTS The writer is indebted to R. E. Heithecker, the Bureau of Mines engineer who had charge of the drilling of tests 13 to 17, for his well-prepared records on the drilling of these tests.

Jan 1, 1933

By Michael Hood

High-volume, low-pressure water jets have been employed for erosion of loosely consolidated rocks for centuries. This excavation method finds application in specialized circumstances even today. The use of high-pressure, low-volume water jets for rock cutting is more recent and was made possible by the development of high-pressure water pumps. Despite the benefits often claimed for these systems, high-pressure water jets still have not found widespread application. In this report, the U.S. Bureau of Mines has reviewed the various methods that have been employed using water jets to break rock and has focused on one method, termed "jet-assisted cutting," which was determined to be the closest to commercial development. The current state of knowledge based on laboratory and field experiences using this cutting method is reviewed, and possible future developments for this approach to excavation are assessed.

Jan 1, 1990

By S. J. Aresco

The Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the composition as shown by proximate analyses. To these, when required, are added the ash-softening temperature, the free-swelling index, and the Hardgrove grindability index. Under most of these specification contracts the bidders guarantee the quality of the coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instruction3 issued by the Bureau of Mines; the samples are analyzed in the Bureau laboratory to determine whether the coal is of the quality guaranteed by the contractor; if it is not, a price adjustment is made. Analyses of the delivered coal and tipple samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) provide valuable data for use in evaluating future bids. In addition, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1969

By Laurel A. Powers

The Bureau of Mines process for recovering Ni and Co from low-grade domestic laterites uses a reduction roast followed by an ammonia, ammo-nium sulfate leach. This investigation examined the waste streams of the process for their potential environmental impact and focused on the laterite residue produced. The U.S. Environmental Protection Agency's extraction procedure (EP) toxicity tests and column leaching showed that leachable metal concentrations would be low enough so that the residue would not be considered a hazardous waste under present definitions. Under nonacid leaching conditions, about the same amount of metal was extracted from laterites as from their residues, and the leachates were similar to water samples from an undisturbed laterite deposit. Washing tests on the laterite residue showed that ammonia and ammonium sulfate concentrations were reduced according to equilibrium stage calculations, resulting in residues that would be acceptable for revegetation. With water washing only, the residue would not be considered a hazardous waste even though significant amounts of Ni and Co were absorbed from entrained leach solution onto the residue. Washing first with fresh leach solution and then with water prevented this absorption and thus improved the overall metal recovery.

Jan 1, 1983

By J. G. Groetsch

Municipal solid waste (MSW) contains about 8 pct ferrous metallics which are typically recovered by magnetic separators at municipal resource recovery facilities. At present, only about 182,500 ton/yr of MSW magnetics are being processed for remelting out of the -11 MMton/yr discarded. The Sn in MSW magnetics makes this material difficult to recycle to the steel industry. An electrolytic method using stannous fluoborate-fluoboric acid for removing Sn was evaluated. Optimum concentrations of Sn in the electrolyte and the effects of impurities such as Al, Cu, Fe, and Pb on Sn recovery from the electrolyte were evaluated. Operating parameters were 60 to 65 g/L fluoboric acid and 20 to 30 g/L Sn using stainless steel electrodes at a current density of 60 A/ft2. Tests were run with postconsumer scrap4 and MSW magnetics. Good results were obtained with MSW magnetics, after pretreatment by reshredding, magnetic separation, and air classification. The final Sn content of the MSW magnetics scrap was reduced from 0.18 to 0.017 wt pct. Heat and solvent treatments of MSW magnetics to remove coatings did not significantly improve Sn removal beyond that obtained with material that had only been mechanically pretreated.

Jan 1, 1984

By Zsuzsanna Zborovszky

[Certain chapters of the tentative document entitled, "Test Requirements for instruments & Apparatus to be Considered for MESA Intrinsically Safe Certification" are evaluated and supporting data are presented on certain key issues with the purpose of helping the regulatory agency in improving the above document. The subjects discussed in detail are: hot wire ignition with W and BeCu wires; the most sensitive methane-air :and propane air ratio; the ignition limits for inductive-resistive circuits in 8.3°; methane-air mixtures in the 24-OV, 100 mH-2 [ ]H range, the resistive ignition limit as a special case when L ? 0; the capacitive-resistive ignition limit representing a four ,dimensional problem is analyzed and discussed in general and the variation of the ignition limit using Vo and/or r2 as a parameter are determined experimentally. The ignition limit is also determined for the [r1 ,~ r2] = 0 case ("capacitor alone") and for the most dangerous capacitive resistive circuit combination. The ignition limits are below the limits proposed in the document. A survey of the different factors influencing the ignition is made as to their suitability to provide a constant safety factor. It is shown that a constant safety factor cannot be achieved. The best method for applying a safety factor appears to be the increase of initial pressure or use of other gas mixture. The revision of the safety factor concept and ignition limit curves is recommended.]

Jan 1, 1980

By C. H. Gorski

Evaluation of raw materials for mineral wool is one phase of the Bureau of Mines broad program for the more effective utilization: of our mineral resources. The experimental work and test-evaluation results on several raw materials as useful components for the production of mineral wool are presented in this report. Samples from all sections of the United States, including copper slag from Tacoma, Wash., pebble phosphate slime from Florida, and granites from Massachusetts and Minnesota, have been blown into mineral wool successfully in the laboratory tests. Maximum conservation of the Nation's mineral and manpower resources requires maximum utility of those resources. Al though the domestic reserves of oil, gas, and coal are tremendous, judicious use of these fuels through the use of proper insulation will insure the highest thermal efficiency. The effectiveness of mineral wool as a heat-insulating material has assumed an increasingly important role in the national economy, and it has become a fuel saver in countless applications. The most immediate concern to many is the use of mineral wool in the home, which promotes uniform temperature and minimizes drafts by reducing heat transfer through the walls, ceiling, and floors. There are, however, many industrial and commercial uses that require large volumes of mineral wool each year.

Jan 1, 1951

By Irving Hartmann

The fire end explosion hazard of excessive coal-dust deposits in mines has been recognized for many years, and important measures have been developed for reducing dust formation and to alley loose dust near its source. Nevertheless, in the course of normal mining it has been estimated that 1 to 3 percent (in some thin, friable seams up to 10 percent) of the total coal mined is reduced to dust of through-20-mesh fineness. In highly mechanized, continuous mining operations the production of fines is even greater. Most dust is trapped near its point of origin and removed from the mine, but large quantities are transported by the air current and by haulage into entries, where the greatest proportion settles on the floor and the balance on the rib and roof surfaces. The latter is generally finer in particle size than the floor dust; this, coupled with its more advantageous position for dispersion, makes the rib-roof dust (also to be referred to as overhead dust) a greater potential explosion hazard.

Jan 1, 1954

The Bureau of Mines is active in programs pertaining to solid waste disposal and land reclamation. Nine reclamation projects of mining companies and six projects of the Commonwealth of Pennsylvania were investigated to provide information on the procedures, costs, and results obtained from reclamation projects of bituminous coal-waste disposal areas. Refuse disposal costs of mining companies ranged from 9 to 28 cents per ton-mile, and quantities disposed of ranged from 600 to 4,500 tons per day. Spreading and compacting the refuse at the dump site ranged from 3 to 20 cents per ton. Cost of covering with soil and planting ranged from $750 to $1,646 per acre. Total costs of reclamation for the Pennsylvania projects ranged from about $1,800 to more than $15,000 per acre. Refuse preparation costs ranged from $772 to $5,550 per acre. Soil covering and planting costs ranged from $1,083 to $5,086 per acre. The best results were obtained by soil preparation and conditioning prior to planting. The type and depth of soil and effect of climate were also factors.

Jan 1, 1973

By C. R. Stephan, N. B. Greninger, J. R. Lipscomb

The U.S. Bureau of Mines and the U.S. Mine Safety and Health Administration (MSHA) are participating jointly in a research program to evaluate the strength characteristics and air-leakage resistance of various proposed seal designs for use in underground coal mines. The full-scale seals were constructed in the USBM's experimental mine at the Lake Lynn Laboratory, air-leakage tested, then subjected to pressure pulses of 20 psig or greater. bjected to pressure pulses of 20 psig or greater. In experiments prior to this study, seven seal designs using solid-concrete blocks were tested. Only the standard-type seal passed the explosion and air-leakage criteria. Tests also were performed on four seals constructed with low-density foam blocks. All four of these seal designs withstood the pressure pulse. In more recent studies, nine cementitious foam seal designs of varying thicknesses and densities were investigated. Six of the nine designs successfully survived the explosion overpressures. Six wood- block convergence seals also have been tested. The typical 3-ft-thick, wood-block seal design currently used in many coal mines did not maintain its integrity, in the absence of convergence forces, following the explosion test. Five modified wood-block seals successfully withstood the 20-psig pressure pulse. Based on these tests, three alternative seal construction materials, cementitious foam, low-density foam block, and wood, have been approved by MSHA for use in underground coal mines.

Jan 1, 1993

By P. D. Lohn

The objective of this program was to develop nozzle designs to maximize the effective cutting length of a water jet. The results of the theoretical program directly support the Bureau of Mines Borehole Mining Program and their experimental program to improve the rock cutting capability of water jets. The borehole geometry requires turning the flow by 90 degrees and accelerating through the nozzle within a restricted length. Several suggestions for turning the flow are offered. The borehole space limitations constrain nozzle length, to the extent that a standard 13-degree tapered nozzle (6-1/2 degrees half angle) is too long to fit in the borehole, at production flow conditions. The design technique developed is computationally economical and enables examination of a large number of shapes and flow conditions. The nozzle design is based on design criteria of minimization of boundary layer thickness at the nozzle exit and minimization of the possibility of separation and cavitation. Six flow conditions, including pressures to 4500 psi and flow rates to 400 gpm, were examined, Best shapes were determined for all flow conditions. The best shape for a borehole reining application consists of an initial 4th degree polynominal (quartic) at the entrance followed by a straight section with a twenty degree (half-angle) taper at the exit.

Jan 1, 1976