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By H. F. Coward, G. W. Jones

"IntroductionIn the course of an investigation on the influence of black damp (a mix of nitrogen and carbon dioxide) on the limits of inflammability of fire damp (methane) in air, some new information was obtained concerning the factors that determine whether or not a gas mixture is capable of self-propagation of flame. Volume for volume, carbon dioxide exceeds nitrogen in its extinctive action on flame, an effect which is generally attributed to the higher molecular heat capacity of the former. Argon, a as of lesser heat capacity than either, proved to Lave less extinctive notion. If, as seemed likely, the extinctive action of a chemically inert gas could be attributed entirely to its heat capacity, then helium should behave like argon; equal volumes of these two oases should exhibit equal extinctive action, for their molecular heat capacities are nearly identical at laboratory temperatures and, in all probability, remain constant up to and beyond flame temperatures. The experiments reported here show, however, that helium has proved to be more extinctive of methane flames than argon.Method Used in ExperimentsThe limits of inflammability of methane, in various ""atmospheres"" composed of mixture of air with one or other of the diluent were determined in a vertical glass tube, 6 feet long and 2 inches in diameter. The lower end of the tube was opened by sliding away a ground-glass joint and the flame of a small spirit lamp was immediately passed across the aperture. The tube was sufficiently long to enable observers to judge whether a flame was self-propagation for if a mixture were incapable of continued self-propagation pf flame, the lamp of flame formel above the source of ignition was extinguished within feet of its passage up the tube."

Jun 1, 1926

By Pablo Velasco

After becoming an oil exporter in 1972, Ecuador experienced a remarkable economic upswing until 1978. However, in 1979 and 1980, a combination of only slight improvements in agricultural output and stagnating petroleum output lowered rates of real gross domestic product (GDP) expansion to 5.3% and 4.3%, respectively. In current prices, the GDP in 1980 was estimated at $11.3 billion.2 The slowdown in growth is attributable in large part to the low level of petroleum exploration in the 1972-79 period. Ecuador's production of petroleum declined 4.5% in 1980 compared with that of 1979. The consortium of Corporación Eatetal Petrolera Ecuatoriana (CEPS), the State oil company, and Texaco, Inc., operating in Ecuador's eastern jungle region was responsible for nearly all of 1980 production, The volume of total crude petroleum exports from Ecuador dropped from 44.7 million barrels in 1979 to 40 million barrels in 1980, although crude petroleum export revenues rose from $1,032 million in 1979 to $1,294 million in 1980- The latter figure represented 54% of Ecuador's 1980 merchandise exports. Crude oil exports accounted far about 46% of the value of 1979 merchandise exports. The total nonfuel mineral exports in 1980 were valued at less than $1 million.

Jan 1, 1982

By L. G. Marshall

This report describes dredging and processing of sand and gravel from a glacial-fluvial deposit in the Raccoon River valley near West Des Moines, Iowa. Preliminary cleaning and separation of the sand and gravel at the dredge site with subsequent transportation to separate plants and the production and disposal of the various grades of aggregate material are also described. The geology of the deposit is summarized. A tabulated summary of costs in units of labor, power, and supplies is included.

Jan 1, 1963

By H. L. Bibbs, H. D. Snedden

"INTRODUCTION The use of beryllium and its alloys has increased rapidly during the last decade. Further expansion of its use is limited; in part, by lack of adequately developed ore reserves. The principal commercial beryllium mineral is beryl, which is found chiefly in pegmatites and produced for market as a byproduct of the mica and feldspar industries. The coarse beryl is mined selectively, sobbed and sorted by hand, and then sold without further beneficiation. The known reserves of coarse beryl are small. No method has been available for concentrating small disseminated beryl crystals, so ores of this type have not been mined or have been left on waste dumps. Disseminated ore in low-grade unmined areas and waste dumps on developed properties is a potential source of beryl, provided a method is developed for its beneficiation.Published literature on the concentration of beryl is lacking in detail or deals chiefly with tests on artificial mixtures of pure minerals, and procedures as given were not applicable to the beryl ores tested at the Salt Lake Station. The testing procedures described in this report are independent developments. By employing these procedures, beryl was satisfactorily con¬centrated from several run-of-mine and dump ores, although these ores wore low in grade and part of the contained beryl was finely crystalline and disseminated.Beryl, quartz, and feldspar, when ground to flotation sizes, are so alike in color and general appearance that they cannot he distinguished by visual observation. The progress of the work depended on rapid determination of the grade of test products by means of the petrographic microscope. Small samples of concentrates and tailings were often cut after each addition of reagents, dried, and examined under the microscope."

May 1, 1947

By D. Oyler

The National Institute for Occupational Safety and Health (NIOSH) Pittsburgh Research Laboratory (PRL), RAG Pennsylvania and Strata Control Technologies of Australia collaborated in an intensive study of ground behavior, reinforcement performance, and stress redistribution at the Emerald Mine in Southwestern Pennsylvania. The study site was a longwall tailgate subjected to a severe horizontal stress concentration. Field measurements indicated that the stresses applied to the study site nearly doubled during longwall mining, resulting in roof deformations extending to a height of 4.8m (16 ft) above the entry. A computer simulation of the field site was conducted using FLAC-2D, incorporating a broad range of rock behaviors and failure mechanisms. Comparison between the measurements and the simulation showed that the model was able to capture the most significant aspects of the roof and support system behavior, particularly, the extensive slip along bedding that created a partially destressed "softened" zone in the immediate roof. The model also showed that supplementing the normal roof bolt support pattern with cable bolts would allow the entry to survive a further 20-25% increase in the applied horizontal stress. Such information could have very practical application to the design of roof support systems for coal mines.

By David R. Jessey

Water pollution problems associated with surface metal/nonmetal mines throughout the United States were assessed. Three major problems were identified: acid mine drainage (AMD), toxic concentrations of heavy metals and excessive sedimentation. Several factors affect the type and amount of pollutants generated at a mine site. Among these are hydrologic regime, geology, mineralogy, topography, climate, size of the mineralized area and mining method. Nine surface mines situated in distinctly different settings were visited and their pollution problems studied. These mines were located in Morenci, Arizona; Hayden, Arizona; Sauharita, Arizona; Cobalt, Idaho; Spruce Pine, North Carolina; Iron Mountain, California; Butte, Montana; Fernwood, Idaho; and DeLamar, Idaho-Oregon. A detailed evaluation of the pollution problems at the Morenci mine indicated that a diversion system and treatment pint would be the most effective means of abatement for the existing water quality problems. Based on the study of the Morenci mine and three other porphyry copper mines with differing problems a water management plan was conceived for a new source copper mine. A companion Appendix Volume containing detailed reports on the mine site visits is on file at the US Bureau of Mines Spokane Research Center.

Jan 1, 1981

By Richard I. Barnhisel

At the Sinclair Study Site it was found that the deeper the soil the greater the yield of corn, soybeans, wheat, alfalfa, and timothy. Yields at this location were generally lower than those at the Alston Surface Mine. At Alston the non-prime land treatments generally produced greater yields for all crops than did the prime farmland treatments, however, the intermediate soil thickness, 20 cm topsoil over 40 cm of subsoil, gave the best yields, provided it's subsoil had been limed. From a chemical point of view, acidic spoils do not need to be buried by 120 cm or 4 feet of soil, provided adequate lime is applied to these spoils as a barrier prior to placement of good quality topsoil and only forage crops are to be grown. The burial depth must be increased to as much as 75 cm when grain crops such as corn or soybeans are to be grown. This response to burial depth appears to be related to water storage needed by the crop and not due to toxic effects of the spoils. A conventional farm tractor-mounted subsoiler increased yields of soybeans and corn the first one or two years, but the effect was diminished with time. Subsoiling did not produce significant increases for alfalfa or wheat. However, ripping with a bulldozer produced significant yield responses, especially for corn and soybeans, that have lasted for at least three years. The ripping effectively reduced the bulk density at least within the zones through which the ripper had passed. Liming the upper 20 cm of subsoil significantly increased yields of alfalfa, corn, and soybeans. There also appeared to be an interaction between this lime treatment and soil depth. Yields of some grain and forage crops may be high enough to meet target levels for bond release for prime farmland. Based on the present study, one should not expect corn yields to be high enough to meet bond release. This statement should not be considered final since the experiment is not complete.

Jan 1, 1983

By H. M. Lawrence

"The land-pebble district, the larger of the two producing areas of Florida, is situated in Polk County and in the eastern part of Hillsborough County. About 80 per cent at the phosphate rock produced in the United States in recent years has been mined from this area. The phosphate ores, locally termed matrix. are beds of sands and clays containing the phosphate pebbles, considered to be Pliocene in age, derived by marine action from underlying Miocene phosphatic marls, and are covered by practically barren sands and clays that have been deposited more recently. Open-pit mining is practiced; hydraulic mining, which has been intensively developed in this district, is used exclusively for mining the matrix and, by some companies for removing the overburden, although drag-line excavators have become established and are proving economical for stripping operations. From the pits the matrix is pumped to adjacent washing plants for beneficiation. The product of the washers. after drying, enters the world markets as Florida pebble phosphate.In this district recovery of the phosphate pebbles by the washing plants has not been particularly effective in the past. The screening, designed to effect a seperation at about 20 mesh (0.033 inches), has not been well controlled. Washer rejects discarded to the waste dumps have contained appreciable amounts of material analyzing above the minimum commercial grade - 66 per cent B.P.L. (bone phosphate of lime). Such losses of commercial fractions should be considered avoidable, and have been discussed at length in a previous paper.3"

Jul 1, 1930

By R. V. Ramani

Procedures have been developed which permit determining in either existing or new mines the optimum diesel equipment deployment schemes and the effect of. diesel exhaust on mine-air quality. Specifically, the following areas are covered in the report: 1. Description of diesel deployment schemes in four underground coal mines that were visited is provided. 2. Description of the analysis procedure to determine the number of shuttle cars required to maintain maximum theoretical continuous miner (or loader) production rates in typical room-and-pillar mining systems and of exhaust contamination resulting from the deployment of diesel powered shuttle cars are provided. Sensitivity analyses to determine the effect of changes in input variables on production and contaminant concentrations are also discussed. 3. Description of the analysis procedure to develop the locomotive operating parameters is provided. Assessment of both production performance as well as estimates of the magnitude of diesel exhaust contamination of the mine air are also made. 4. Recommendations for extensions of this research are outlined and include developing and testing procedures for 1) determining equipment duty cycles for the diesel equipment, and 2) studying the exhuast contamination of mine air on the basis of these duty cycles.

Jan 1, 1978

By L. B. Phelps

A method is presented for the burial of potentially toxic spoil in high density zones or packages within spoil piles. Such burial could reduce the outflow of pollutants and thus minimize contamination of groundwater flows. Laboratory model studies using ammonium bromide tracer were performed to quantify the expected outflow mixing that could be achieved through package construction in spoils. Field drilling and geophysical density logging of spoils was carried out at three sites in Pennsylvania and Ohio to obtain a range of field spoil bulk density measurements and spoil samples. These data are analyzed to determine the relationships between spoil density and the controlling factors of lithology, depth, age, particle size distribution and mining method. A separate series of spoil permeability tests were performed in the laboratory to investigate the relationship between permeability and its related parameters. Research results are applied to the toxic package method to suggest guidelines for pack-age size, shape, density and placement for future field prototype development.

Jan 1, 1981

By A. H. Shoemaker

This paper describing the mining practices at the Old Dominion mine, Globe, Ariz., is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various minim districts in the United States. The Old Dominion mine is situated in the eastern port of the Globe-Miami district, about 1-1/2 miles north from the center of the town of Globe. An average of nearly: 1,200 tons per day was mined during 1928. The prevent production is about 1,500 tons per day; of this amount,, approximately 100 tons is direct-smelting ore that is shipped to the smelter at Miami and 1,400 tons milling ore which is treated in the company?s concentrator at Globe. About 600 men are employed at the mine.

Jan 1, 1930

By R. W. Stahl

Burning coal-mine refuse banks were surveyed in 15 States. The following characteristics were tabulated for 495 hanks: County; name, population, and distance of nearest town; size and status of bank; status and stage of fire; and topography. Ways of controlling fires were reviewed, the compacting and sealing method proving most satisfactory. Means for preventing refuse-bank fires by proper construction of banks are described.

Jan 1, 1964

By F. J. Perzak

The Bureau of Mines conducted a flammability study of plastic ventilation ducts. Six rigid 16-in-diam fiberglass-reinforced plastic ducts from five manufacturers were examined using laboratory-scale, large-scale, and full-scale fire tests. The laboratory-scale tests included the American Society for Testing and Materials E162 radiant panel test, the E2863 oxygen index test, and the standardized small-scale flammability test (S3FT) developed by the Mine Safety and Health Administration (MSHA), U.S. Department of Labor, and replicated by the Bureau of Mines. Ten-foot lengths of the same ducts were also subjected to a large-scale vertical fire test, and 20-to 30-ft lengths were tested in a full-scale in-mine fire test at the Bureau's Lake Lynn Laboratory mine. The data from the laboratory-scale radiant panel test and oxygen index test indicated that the ducts were fire-resistant, However, five of the six ducts failed the S3FT and vertical fire tests, and four of the ducts failed the full-scale in-mine tests with flame propagation rates that ranged from 3 to 10 ft/min. The results indicate the need for improved fire-resistant plastic ducts. The good agreement between the S3FT re-sults and the vertical and full-scale tests show that the S3FT provides a good indication of the flammability of fiberglass-reinforced plastic ducting under realistic fire conditions.

Jan 1, 1987

By D. Bienstock

To develop a rugged catalyst capable of withstanding hydraulic attrition resulting from the oil-circulation process for synthesizing liquid fuels, use of an iron catalyst containing an active coating surrounding an inert solid core of metal was investigated. This massive-iron catalyst in the form of steel shot and lathe turnings was activated by partial oxidation with steam at 600° C, impregnated with alkali, and reduced with hydrogen at 450° 6. The massive-iron catalysts were resistant to oxidation and spalling, and a 6-month catalyst life was attained. Higher operating temperatures could be employed than with fused iron oxide catalysts, resulting in greater gasoline yields. Because the lathe turnings pack with void volumes of 70 to 90 percent, it has become possible to employ a fixed bed without the danger of cementation that occurs with fused iron oxides.

Jan 1, 1963

By William N. Patterson

This report describes the design and testing of an improved quiet hard rock percussion drill. The improved drill incorporates a tappetless design with independent rotation in a hand held drill weighing 50 lbm. Laboratory and field testing in three mines were conducted. The testing showed improved drilling performance with no increase in measured noise levels over the fist design.

Jan 1, 1985

By J. B. Elizondo

This paper, which describes mining methods and practices at the Piokee mining unit and the Piokee expertmental mining project of The Eagle-Picher Co. in northeast Oklahoma, is one of a series being prepared by the Federal Bureau of Mines on mining methods, practices, and costs in various mining districts of the United States. The Piokee unit, comprising the Piokee, Rowe, Lucky Syndicate, and parts of the Netta White and Otis White leases, is in the SW1/4, W1/2NW1/4SE1/4, and W1/2SW1/4SE1/4 sec. 17, T. 29 N., R. 23 E., Ottawa County, Okla. (figs. 1 and 2), The 200-acre tract is adjacent to the town of Picher and near the heart of the Picher field of the Tri-State zinc-lead mining district.

Jan 1, 1959

As mining operations in the United States (US) have become more productive, controlling the dust exposure of mine workers has become more challenging. In response, US mining operations are applying basic controls at elevated levels and are looking to emerging control tech­nologies in an effort to better control airborne respirable dust levels. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) conducts research to develop and/or improve control technologies that reduce the respirable dust exposure of workers in underground coal mines. The goals of this research involve optimizing the use of water sprays and ventilating air, as well as, evaluating emerging control tech­nologies. An overview of dust controls typically utilized in underground US coal mines will be provided. An update on ongoing PRL research efforts that are evaluating new control technologies will also be presented.

Jan 1, 2008

By Stephen D. Smith

The following tables summarize data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in these tables is what is termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines. Because of inadequacies in the statistics available, some series deviate from the foregoing definition. For copper, gold, lead, silver, tin, and zinc, the quantities are recorded on a mine basis (as the recoverable content of ore sold or treated). However, the values assigned to these quantities are based on the average selling price of refined metal, not the mine value. Mercury is measured as recovered metal and valued at the average New York price for the metal. The values shown are in current dollars, with no adjustments made to compensate for changes in the purchasing power of the dollar.

Jan 1, 1995

By Sheridan J. Rodgers

Toxic fumes generated during shot firing were measured in a phosphate rock mine and a copper mine. Fumes generated during firing of explosives in the Bureau of Mines 1350 ft3 test chamber were measured also. The release of fumes from water gels, ammonium-nitrate oil mixtures and nitroglycerin based explosives was studied. Direct reading instruments were used to monitor the fume concentrations. The amount of CO produced per unit weight of nitroglycerin explosives (0.41 ft3/200 grams) was higher than that produced by ammoniumnitrate-oil mixtures (0.24 ft3/200 grams) and water gels (0.16 ft3/200 grams). The amount of NOx produced by nitroglycerin based explosives was also higher than the amount produced by water gels or ammonium nitrate-oil mixtures.

Jan 1, 1976

By Richard Rittenhouse

This program was to develop a new base line system for automated continuous room and pillar type mining. The primary requirement estab¬lished for this machine is that the machine be capable of mining and bolting simultaneously. Additionally, this machine was to provide temporary and permanent roof control, have a productive - full - face semi-automatic mining system, leave a clean entry outby the machine, provide maximum operator protection, provide effective dust suppression and provide air scrubbing to restrict respirable dust to permissible levels. The machine has effectively demonstrated the ability to mine and bolt simultaneously. Additional above ground operation, testing, and time studies are recommended to further verify the machines abilities. Design improvements are recommended for future generation AES machines. These relate to marginal design areas such as side loading on vent duct lift cylinders, etc., that will not impair additional testing of the existing machine.

Jan 1, 1983