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By S. J. Schatzel, W. P. Diamond

High methane emissions originating from the active face areas and from the fractured formations overlying and underlying the mined coalbed can adversely affect both safety and productivity in underground coal mines. Since ventilation alone may not be sufficient to control the methane levels in the longwall mining environment, gob gas ventholes have become a standard supplementary methane control option in many mines. As mines progress into deeper and gassier coalbeds, or as longwall panel size increases, ventilation and gob gas ventholes together may not be sufficient to maintain methane levels within statutory limits. To decrease the risk associated with methane emissions under these circumstances, in-seam horizontal methane drainage is often used to reduce the gas content of the coalbed prior to mining. Horizontal methane drainage borehole completion designs, drilling strategies, and degasification lead times may need to be adjusted for site-specific conditions due to mine design, geology, and the gas content of the coalbed. This study investigates different horizontal methane drainage borehole patterns, borehole lengths, and degasification times prior to and during panel extraction to evaluate their effectiveness in reducing methane emissions using a "dynamic" 3D reservoir modeling of a 38 1-m wide longwall panel operating in the Pittsburgh coalbed. Results of this study showed that dual and tri-lateral boreholes are more effective in decreasing emissions and in shielding the entries compared to fewer shorter, cross-panel, horizontal boreholes parallel to the longwall face. Modeling results showed that after 12 months of pre-mining methane drainage, the average longwall face emission rates can be reduced by as much as 10.3 m3/min and 6.8 m3/min using tri- and dual-lateral boreholes, respectively. It was also shown that if pre-mining methane drainage time is short, it is important to continue methane drainage during the panel extraction to maximize reductions in longwall face emissions since additional face emission reductions achieved during this period can be comparable to pre-mining degasification.

By Stephen Krickovic, J. E. Carpetta, T. D. Moore

Air quantity-pressure and methane concentration surveys were conducted by the Bureau of Mines in accessible portions of an area being pillared in a Pittsburgh coalbed mine in West Virginia. These included two mined-out and three active butt headings and a bleeder system. The particular mine workings were started in virgin coal directly from a set of main headings; the main reason for the study was the difficulty usually encountered in adequately bleeding the gobs under such conditions. Although the two separate return airways in each active butt heading and the North and 1 Left bleeders contained acceptable methane concentrations (0.01 to 0.78 percent in the butts and 0.73 to 1.0 percent in the bleeders) with significant total methane removal (109 cfm in butts and 631 cfm in bleeders), there were relatively large areas in the gobs with possible minimal airflows. This condition appears to have developed from lack of systematic regulation of the airflow across the gobs and appears to indicate the existence of considerably more methane in the probably low flow areas in the gob.

Jan 1, 1973

By F. D. Sutterfield

This study was conducted to provide experimental evidence on the effect of modifications of gasoline front-end composition on the photochemical specific reactivities of automotive emissions. Evaporative and evaporative-plus-exhaust emissions from an automobile operated with four fuels of different volatility and varying levels of C.-C5 olefins were irradiated in a 10040 environmental chamber at three sets of initial hydrocarbon-nitrogen oxides concentrations. Reactivity was measured and expressed in terms of rate-of-NO2 formation and dosages of oxidant, peroxyacetyl nitrate, and formaldehyde. The compositional changes that were necessary in reducing fuel volatility were found to have no significant effect on the reactivity of the emissions. However, replacing C4-C5 olefins with saturated components resulted in sharp decreases in all reactivity manifestations observed for the evaporative emission samples. A lesser influence (of C4-C5 olefin replacement) was found with the composite exhaust-plus-evaporative samples; the effect that was observed could be attributed to the evaporative emission portion of the sample. The data therefore suggest that saturation of front-end fuel olefins had no large effect on exhaust emission reactivity.

Jan 1, 1971

By G. D. Jermain

The Bureau of Mines investigated the Gypsum-Camel deposit on Iyoukeen Cove Chichagof Island, Southeastern Alaska, from April 21 to August 26, 1948, as A part of the United States Department of the Interior program for developing an Alaskan construction industry. As gypsum is one of the components necessary for the manufacture of cement and one of the raw materials for plaster and plaster-board products, it is desirable to locate and develop a readily accessible deposit of gypsum in Alaska. In 1928, B. D. Stewart of the Territorial Department of Mines surveyed the gypsum deposits at Iyoukeen Cove, and during the summer of 1946 George M. Flint, Jr., and Edward H. Cobb of the Federal Geological Survey examined and mapped the old workings at Gypsum Creek and the prospect at Iyoukeen Cove. Both the Territorial Department of Mines and the Federal Geological Survey recommended the Gypsum-Camel prospect as warranting a diamond-drilling program by the Bureau of Mines. The Bureau of Mines project consisted of cleaning out and sampling, the old underground workings and diamond drilling from the surface to ascertain the lateral extensions of the deposit.

Jan 1, 1952

By J. Kruttschnitt

This paper, describing milling practice at Mount Ira Minis, is one of a series covering milling methods and cost that is being published by the Bureau of Mines, United States Department of the Interior. The Mount Isa concentrator began operations in day 1931 by treating a mixture of oxidized and sulfide ores. Since March 1935 only sulfide ores have been milled; this change involved major alterations to the flow sheet. The maximum capacity on mixed oxide and sulfide ores was 2,650 tons per day; the present capacity is approximately 1,880 tons of sulfide ore per day. The installation of additional crushing, grinding, and flotation equipment when completed early in 1939 will increase the maximum capacity of the concentrator to 2,240 tons of sulfide ore daily.

Jan 1, 1939

By R. W. Crocker, H. H. Clark

The purpose of the investigation discussed in this bulletin, one of a series dealing with the use of electricity in mines, was to study the various means and methods used to confine the flashes that occur when a switch carrying electric current is opened. The flash result- ing from the opening of a 250-volt direct-current circuit carrying more than half an ampere will ignite explosive mixtures of mine gas and air. An equally dangerous flash may be produced by even less cur- rent from a 500-volt circuit. Few mine electric circuits carry less than half an ampere when in use. The need of protecting the switches of such circuits in places where gas is likely to be present is therefore obvious. Two general methods have been proposed for preventing switching flashes from igniting gas surrounding the switch. One method is to inclose the switch in a casing provided with openings that are covered with wire gauze or otherwise designed and equipped for preventing the passage of flames from the interior to the exterior of the switch casing. Switches so protected are called explosion-proof switches. The second method is to immerse the switch contacts in oil to a depth sufficient to quench any flash that may occur when the switch is operated. Switches so protected are called oil switches. The success of the first method of protection depends upon the proper design and construction of the switch casing. It is essential to the successful operation of the second method that the switch contacts be surrounded by the proper kind of oil in good condition. There are several ways in which an oil switch may be deprived of its protective feature. The oil tank may not be filled or, if filled, the oil may leak out or be spilled. The oil tank may be removed (in some designs) and not replaced or through neglect the condition of the oil may become such that it is no longer an efficient protection. While such contingencies are not likely to occur, and although oil switches may be so designed that the loss of oil is not probable, nevertheless, as compared with oil switches, explosion-proof switches seem to

Jan 1, 1913

By A. W. Fahrenwald, W. W. Staley

"In flotation concentration, various machines are employed for agitation and aeration of the ore pulp in the operation of frothing. The power required in the operation of these machines varies considerably with the type and make of machine used. The object of this investigation was to determine the effect of certain physical properties of the pulp particularly viscosity, density, and temperature - upon the power required by certain forms of pulp agitators.The viscosity factor is most involved because it is affected by temperature and by density. Viscosity of liquids and suspensions has been extensively studied and the physics and mathematics of the subject are much enlarged upon in books and in the literature. It is not, however, the intention of this study to become involved in the intricacies of these phases of the subject.The agitation of the various mediums in the experimental work did not last long enough to cause a measurable rise in temperature from the ""beating"" of the medium, hence no cognizance is taken of this factor.No attempt has been made to correlate the data obtained with the impeller with any information regarding centrifugal pumps. The object sought here is quite foreign to the problems of pumping. The impellers used are ""open"" and air is involved.The experiments performed and the data obtained are presented. Only that amount of discussion necessary to make the results understandable is given.Tap water was used in all experiments. A comparison of distilled water and tap water showed no measurable difference. In the experiment in which sodium chloride was needed, the commercial salt as used in fire assaying was taken. The quartz was of the ""bull quartz"" variety, thoroughly washed free of iron oxide."

Jun 1, 1930

By R. L. Grayson, W. E. Wallace, M. D. Attfield, A. Q. Wearden, P. Bolsaitis, R. D. Kennedy, M. J. Keane, J. C. Harrison

"Respirable high-silica particles from four coal mines. a clay mine and a tunnelling site were analysed for silicon vs aluminum composition by performing scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDS) at electron accelerating voltages of 20 kiloelectron volts (keV). The same particles were analysed at 5 keV to determine possible differences in surface vs bulk composition. In some cases high-silica particles exhibited a decrease in the ratio of silicon to aluminium K-alpha line intensities with decreasing electron beam accelerating voltage. This behaviour is consistent with aluminosilicate surface contamination or occlusion of a silica particle. Some 20 high-silica particles were analysed from each of 10 samples. Powdered aluminosilicate glass was used as a control for the behaviour of silica with a homogeneous distribution of aluminium in the particle. Significant differences were found between the control and sample means for an Illinois bituminous coal mine dust, two western and one central Pennsylvania bituminous coal mine dust low-temperature ashes. and a clay mine and mill dust sample, but not for an anthracite coal mine dust and two central Pennsylvania bituminous coal mine dust low-temperature ashes. INTRODUCTIONRESPIRABLE dust quartz content commonly is measured on bulk samples by using i.r. spectroscopy or X-ray diffraction. For research purposes, individual particle-by particle SEM-EDS analysis at 20-30 keV electron beam accelerating potential may be used also. Such measurements have not provided an unambiguous association of quartz content with occupational pulmonary disease prevalence in exposed workers (WALTON et al., 1977). Rather, there is evidence that coal rank modifies the relationship between dust exposure and pneumoconiosis development (WAL TON et al., 1977; ROBOCK and BAUER, 1990; ATTFIELD and MORRING, in press). SEM-EDS analysis was performed to measure the silicon fraction, Si/(Si +Ai), at 20 and at 5 keV on high-silica particles to determine if some respirable quartz particles generated by mining exhibit heterogenous composition with depth (WALLACE et al., 1990), which might affect the bioavailability of the quartz surface."

Dec 1, 1995

By Joseph L. Condon

High-speed movies were taken of crater experiments in two-dimensional plates of Tennessee marble to study craters being formed primarily by stress-wave action. The contribution of gas action to the cratering process was minimized because the two-dimensional models did not contain the expanding gases from the explosive. Four burdens were studied for solid plates and one burden for a segmented plate. After cratering, the plates were reassembled for dye penetrant studies of fracturing. Flyrock velocities were calculated and related to the degree of fracturing, and compared with those from quarry shots. In general, the smallest burdens produced the highest flyrock velocities and the least amount of fracturing. Flyrock velocities compared favorably with initial flyrock velocities in quarry blasts, but did not show step accelerations due to gas effects as did the quarry blasts. The test with a segmented plate was used to simulate cratering in a jointed material and showed that stress-wave effects can be important for crater formation in jointed rocks.

Jan 1, 1972

By Charles P. Lazzara, Alex C. Smith, Richard W. Pro, Mark W. Ryan

The U.S. Bureau of Mines conducted a study to determine if commercially available automatic sprinklers could withstand the high static pressures in deep underground coal mines without leaking and if exposure to the mine environment affected their leak pressures. New sprinklers and sprinklers exposed to the mine environment were subjected to increasing pressures until leakage occurred. The average leak pressures of the new sprinklers ranged from 640 to 2,300 psig and were significantly different for sprinklers from different manufacturers and for different types of sprinklers. Different for sprinklers from different manufacturers and for different types of sprinklers. Generally, standard-response sprinklers withstood higher pressures than fast-response sprinklers. The results indicated that most commercially available sprinklers would withstand the high static pressures in deep underground coal mines; however, they would not provide the same reliability and safety factor as sprinklers used aboveground at or below their rated pressure of 175 psig. The average leak pressures of the sprinklers exposed to the mine environment ranged from 740 to 1,180 psig. The mine environment affected the ability of 66% of the sprinklers to withstand high static pressure New sprinklers were also evaluated at pressures of at least 500 psig for 30 days to determine their ability to withstand long-term exposure to high static pressures; no leakage was observed.

Jan 1, 1993

By K. K. Kelley, W. W. Weller

Heat capacity measurements of akermanite ( Ca,MgSiO ) , cordierite (Mg2A14 Sig018 ) , gehlenite ( Ca₂Al₂ SiO ) , and merwinite ( Ca ,MgSiO ) were conducted over the temperature range from 50 ° to 298.15 ° K. The entropies at 298.15 K ( expressed in cal / deg mole ) were evaluated as follows : Akermanite , 50.0 ± 0.5 ; cordierite , 97.3 ± 0.9 ; gehlenite , 47.4 ± 0.4 ; and merwinite , 60.5 ± 0.5 . All four compounds have positive entropies of formation from their constituent oxides at 298.15 ° K ; the values range from 4.6 cal /deg mole for akermanite to 10.1 cal / deg mole for cordierite .

Jan 1, 1963

By K. K. Kelley, W. W. Weller

The heat capacities of four crystalline silicates of barium ( BaSiO3 , BaSiO4 , Ba Si¸0 , and BaSi₂0 ) and two crystalline silicates of strontium (SrSio and Sr₂Sio ) were measured over the temperature range from 51 ° to 298° K. The results were used to evaluate the entropies at 298.15 ° K. The entropy values were joined with known heats of formation to obtain the free energies of formation of the silicates with respect to their constituent oxides at 298.15 ° K.

Jan 1, 1964

Viable domestic mineral industries are essential to the economic health of the United States and the well-being of its citizens. The charts in this publication reflect developments significant to the Nation's mineral industries during 1975. Last year was a year of reduced activity for the Nation's mineral industries. Although the value of the country's total mineral output rose, for example, the overall production and use of many minerals fell. At the same time, the industry experienced lower profits and higher debt/equity ratios. These and other adverse effects on many segments of the Nation's mineral industries resulted from the overall decline in domestic and international economic activity.

Jan 1, 1976

By S. M. Shelton, F. D. DeVaney, M. M. Fine

Ferrograde manganese ore or its equivalent is essential to the manufacture of every ton of steel produced ; although it is well -known that there are large deposits of low - grade ore in the United States , the production of substantial amounts of ferrograde material from domestic sources presents a problem that becomes more and more critical as the stockpiled ore is depleted through inability to obtain adequate supplies from foreign sources . Consequently, a program of laboratory and pilot - plant investigations designed to solve the problem of obtaining a domestic supply of manganese has been undertaken by the Metallurgical Division, Bureau of Mines . This paper is one of a new series that will include reports of results obtained in the various investigations conducted under the manganese program . The scope of the program and the organization that was set up to direct and supervise the work were discussed in the foreword of the first paper of this series , Report of Investigations 3606 , Manganese Investigations 1. Concentration of Manganese Ores from the Drum Mountain District, Utah, by S. R. Zimmerley, J. D. Vincent , and C. H. Schack . Other reports will be published as the work progresses .

Feb 1, 1942

By Webster S. Anderson

Two series of tests were run with planer model 'BB": one at the Arickaree mine of the San Francisco Chemical Co., Rich County, Utah, and one at the Roslyn No. 9 mine of the Northern Pacific Railway Co., Roslyn, Wash. The tests at the Arickaree mine were started on June 25, 1958, and continued until September 30, 1958. Prior to these tests, an electrically activated remote-control system was installed, and other modifications were made on the planer. The tests showed that the planer in general and the remote-control system worked very well; however, the various cutting tools used would not consistently penetrate and cut the phosphate rock. This indicated that the cutterhead design had to be changed before the planer would operate efficiently in phosphate beds similar to the "A" bed in the Arickaree mine.

Jan 1, 1962

By John C. Edwards

Chapman-Jouguet detonation calculations were carried out for pentaerythri-tol tetranitrate (PETN), TNT, and ammonium nitrate-fuel oil (AN-FO) explosives using the compressibility form of an equation of state of hard spheres based upon Percus-Yevick (PY) theory, and a chemical equilibrium detonation code called TIGER. Similar calculations were also carried out with the Becker-Kistiakowsky-Wilson (BKW) equation of state. For PETN, the BKW equation gives somewhat better agreement with experimental values of detonation velocity and pressure. However, in terms of experimental temperatures and concentrations of the minor product species (NO), the predictions of the PY equation are shown to be more satisfactory. Similar comparisons of experimental and theoretical results for TNT and AN-FO indicate that the PY equation has general utility in predicting the detonation properties of condensed explosives at moderate loading densities (Po < 1.3 g/cm3).

Jan 1, 1974

By William H. Schiffbauer

One of the safety and health research programs of the former U.S. Bureau of Mines Pittsburgh Research Center was the evaluation of technology that will provide remote-controlled operation of mechanized equipment in underground room-and-pillar mining. The purpose of this effort was to enable workers to be located away from the hazardous and unhealthful coal extraction area (the face). As part of this program, advanced machine navigation and control technologies were developed for underground room-and-pillar and highwall coal mining that can be applied to commercially available mining equipment. These technologies use off-the-shelf components and a flexible control software architecture to minimize the effort required to adapt them to mining equipment. An accurate, reliable navigation system that can provide the mining machine&apos;s heading and location is a critical requirement for a remote-controlled mining system. After investigating several different types of navigation sensors, researchers selected the Honeywell Ring Laser Gyro Inertial Navigation System (INS) as showing the most promise. It was installed on a continuous mining machine at our Mining Equipment Test Facility. Extensive testing at an open pit (OP) site was also performed. This report describes the INS as it was employed on the mining machine in the laboratory, in the field, and OP tests, and provides the accuracy and performance results of the OP and highwalltests.

Jan 11, 1997

By J. E. Zeilinger

This Bureau of Mines report describes the preparation characteristics of the significant coalbeds of Clarion County, Pa. Of the 15 samples collected, 1 was of metallurgical quality as received, 4 could be sufficiently upgraded to provide acceptable products, and the remaining 10 samples could not be upgraded to metallurgical quality because their sulfur contents could not be lowered to meet the standard. For steam or power generation, 1 sample was of low sulfur content as received, 1 sample could be upgraded to low sulfur content, and 10 samples could be upgraded to medium sulfur content. The original sulfur content of the remaining three samples can be appreciably reduced by removal of the sink 1.58 specific gravity material; however, these coals would be classified as medium sulfur coals both before and after removal of the sink material.

Jan 1, 1968

By B. J. Scheiner

Extraction of silver from silver mill tailings by an electrolytic oxidation procedure was investigated by the Bureau of Mines. Various parameters affecting silver extraction, such as electrolysis time, particle size, and dissolution of the silver as the tetrachloro or cyanide complex, were studied at 30° C with an electrolyte concentration of 20 weight-percent sodium chloride. Resulting silver extractions ranged from 77 to 90 percent, depending on the tailings being treated. Concomitant extraction of mercury ranged between 90 and 95 percent. Power consumption was 52 to 90 kilowatt-hours per ton for the tailings investigated. Comparative experiments using direct cyanidation resulted in extraction of 46 to 82 percent of the silver and 20 percent of the mercury. Cyanide consumption ranged from 3.3 to 9.4 pounds per ton of tailings, depending on the tailings being treated. Silver and mercury were recovered from leach solutions by precipitation on iron powder, followed by conventional distillation and fire refining steps.

Jan 1, 1972

By J. M. Stuve

Provisional values for the heat of formation of europium trichloride and europium sesquioxide were determined by solution calorimetry utilizing europium metal of more than 99-percent purity. The resulting values for the heats of formation of Eu203 (cubic) and EuCls (hexagonal) were -386,970 ±l,200 cal/mole and -218,740 ±650 cal/mole, respectively, measured at 298.15° K.

Jan 1, 1965