Results 21 - 30 of 32

• Lightning Propagation Through the Earth and its Potential for Methane Ignitions in Abandoned Areas of Underground Coal Mines
  10/1/2002 - Conference papers
  This paper addresses the question, 'Can lightning cause potential differences capable of igniting methane-and-air mixtures at overburden depths at which underground coal mining occurs?'
• Technology News 490 - An Inexpensive Device for Monitoring Explosions in Sealed Areas of Underground Mines
  6/1/2001 - Technology News
  Description of a passive, inexpensive technique for monitoring explosion overpressures within sealed areas in underground coal mines.
• Technology News 489 - Reducing the Danger of Explosions in Sealed Areas (Gobs) in Mines
  5/1/2001 - Technology News
  Techniques are identified to reduce the probability of gob gas explosions.
• Coal Mine Seismicity and Bumps: Historical Case Studies and Current Field Activity
  8/1/2000 - Conference papers
  Research on techniques that will reduce the hazards in the mining workplace associated with coal bumps.
• Technology News 448 - Improving the Performance of Longwall Gob Gas Ventholes
  3/1/1995 - Technology News
  The absence of fundamental scientific and engineering principles in the design and placement of gob gas ventholes can cause difficulties for mine operators when gas emissions increase because of a change in mine design or because variable geologic condi...
• Behavior of Simulated Longwall Gob Material
  1/1/1993 - Reports of Investigations
  This report presents results of a U.S. Bureau of Mines study of longwall gob material. The objective of this work was to determine material stiffness properties of the gob for use in numerical models or rock mass response to longwall mining.
• Determining the Source of Longwall Gob Gas: Lower Kittanning Coalbed, Cambria County, PA
  1/1/1992 - Reports of Investigations
  Four coreholes were drilled at a longwall mine in the Lower Kittanning coalbed to obtain coal and rock samples from overlying strata to determine their gas content during the mining cycle. Test results indicate that 91% of the gas came from coalbeds.
• Evaluating Ventilation Parameters of Three Coal Mine Gobs
  1/1/1986 - Information Circulars
  The Bureau of Mines used sulfur hexafluoride (sf6) tracer gas to evaluate the effectiveness of gob ventilation and/or sealing practices at three coal mines, each having different problems associated with their mined-out areas.
• Control of Longwall Gob Gas With Cross-Measure Boreholes (Upper Kittanning Coalbed)
  1/1/1983 - Reports of Investigations
  The cross-measure borehole technique is being studied as an alternative to the use of surface gob boreholes as a means of controlling methane in gobs during longwall mining. Small-diameter holes are drilled from underground locations into strata overlyi...
• Underground Gob Gas Drainage During Longwall Mining
  1/1/1982 - Reports of Investigations
  The Bureau of Mines is developing underground gob gas drainage as an alternate means of methane control for U.S. longwalls. Holes are drilled into the roof over the panel and on retreating longwalls, towards the working face from a location inby the fac...