Results 81 - 90 of 149

• A Review of the Mechanisms of Gas Outbursts in Coal
  1/1/1987 - Information Circulars
  Outbursts are sudden and violent releases of gas and coal that result from a complex function of geology, stress regime, and gas pressure and content. The Bureau of Mines has reviewed methods for prediction and mitigation of such outbursts in use worldw...
• Method Factors for Anemometer Measurement at Pipe Outlets
  1/1/1987 - Reports of Investigations
  Gob holes are routinely used by the mining industry to vent methane from gobs and to prevent it from entering the mine ventilation system. In some cases, flows from gob holes are measured by centering an anemometer on the end of a discharge pipe. These ...
• Methane Contents of Oil Shale From the Piceance Basin, CO
  1/1/1987 - Reports of Investigations
  The Bureau of Mines determined the gas contents of 135 oil shale samples obtained from approximately 630 ft of core drilling. Drilling was done within a projected mining zone of the Cathedral Bluffs Mine, located in the Piceance basin of western Colorad...
• Comparisons Between Cross-Measure Boreholes and Surface Gob Holes
  1/1/1986 - Reports of Investigations
  The Bureau of Mines conducted studies to compare the effectiveness of the cross-measure borehole system with that of surface gob holes on two successively mined retreating longwalls in the Lower Kittanning coalbed. Only the cross-measure system was in o...
• Investigation of Similarities Between Methane Drainage Potential of Utah's Sunnyside Coalbed and Eastern U.S. Coalbeds
  1/1/1986 - Reports of Investigations
  An investigation of the effectiveness of methane drainage in the lower Sunnyside coalbed at Kaiser Steel Corp. Sunnyside No. 1 Mine in Utah. Most previous attempts to drain methane gas using long horizontal holes were conducted in the eastern coal provi...
• Short-Delay Blasting in Underground Coal Mines
  1/1/1986 - Information Circulars
  Research was conducted to determine whether the total elapsed delay time for blasting bituminous coal in underground coal mines could be safely expanded beyond the 500-ms limitation without igniting a methane or methane-coal dust atmosphere.
• Results of Direct-Method Determination of the Gas Content of U.S. Coalbeds
  1/1/1986 - Information Circulars
  This report presents a data base of gas content data. The data are presented in tabular form, by coalbed name and state. The components of the total gas content (lost, desorbed, and residual gas) are given. Location (state and county), sample depth, coa...
• Evaluation of Safety Shutoff Valve System on Methane Gas Pipelines Under Mine Fire Conditions
  1/1/1986 - Information Circulars
  The goal of this research was to evaluate the integrity of existing shutoff valves and actuators used under high-temperature conditions in the Bureau of Mines' horizontal borehole methane drainage pipeline system and to determine system improvements.
• Methane Control on Longwalls with Cross-Measure Boreholes (Lower Kittanning Coalbed)
  1/1/1985 - Reports of Investigations
  The cross-measure borehole technique is an effective method of controlling methane liberated by fracturing the roof strata in longwall gobs where overburden is less than 750 ft (229 m). About 71 pct of the methane produced by longwall mining in the Lowe...
• Measuring Formation Pressures and the Degree of Gas Drainage in a Large Coalbed Gas Drainage Field
  1/1/1985 - Reports of Investigations
  The Bureau of Mines and United States Steel Corp. are conducting a joint project to monitor formation pressures at a large (23-well) coalbed gas drainage field near Oak Grove, Alabama. Three monitor holes were drilled in late 1981, and pressure monitori...