Dynamic Seals: A Way to Prevent Longwall Gob Explosions

Details

• Personal Author:
  Brune, Jürgen F. ; Saki SA
• Description:
  Longwall coal mining leaves large areas where the coal has been made removed and the roof rock strata collapse, forming a zone of broken rock rubble called the gob. Figure 1 shows a typical longwall gob area along with the gate roads. The ventilation pattern for progressively sealed longwall panels follows a simple "U" pattern where fresh air is coursed inby to the headgate, flows along the face and exhausts through the outby tailgate as shown in figure 1(a). An important variation of this pattern is the back return (BR) arrangement where the exhaust air from the face is drawn inby and around the nearest open cross cut before it turns in the outby direction towards the exhaust fan. Figure 1(b) illustrates the use of back return. This arrangement moves the point of low pressure from the tailgate corner up to 60 m inby and thus maintains fresh air in the tailgate region that could otherwise be contaminated with gob air. The gob area may contain remnants of unmined coal or parts of overlying coal beds that continue to release methane, eventually filling the gob area with methane in concentrations far above the explosive range of about 4.5 to 15%. Many gob areas must be equipped with gob ventilation boreholes (GVBs) to extract methane, and GVBs often exhaust methane at concentrations from 50% to 90% (Saki, 2016). Due to oxidation processes occurring in the gob, the oxygen content is reduced to a low level, with nitrogen and CO2 making up the major remaining components of the gob atmosphere. [Description provided by NIOSH]
• Subjects:
  Explosions Occupational Health Safety Ventilation
• Keywords:
  Explosion Prevention Explosive Gases Longwall Mining Methane Control
• Publisher:
  Society for Mining, Metallurgy, and Exploration, Inc.
• Document Type:
  Text
• Funding:
  Contract
• Genre:
  Proceedings
• Place as Subject:
  Colorado ; Maryland ; OSHA Region 3 ; OSHA Region 8
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-3
• NIOSHTIC Number:
  nn:20069041
• Citation:
  2017 SME Annual Meeting, February 19-22, 2017, Denver, Colorado, preprint 17-046. Englewood, CO: Society for Mining, Metallurgy, and Exploration, Inc., 2017 Feb; :1-3
• Federal Fiscal Year:
  2017
• Performing Organization:
  Trustees of the Colorado School of Mines
• Peer Reviewed:
  False
• Start Date:
  20140901
• Source Full Name:
  2017 SME Annual Meeting, February 19-22, 2017, Denver, Colorado, preprint 17-046
• End Date:
  20190831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:4c293874aa3f674a15b4765fb724cf23dc04bae48ee4bef5bbc19e312db8989c1e2c4a75d5effe12c261f6f617c0b3207be7a6dcad479a6c3e01e8598440c94a
• Download URL:
  https://stacks.cdc.gov/view/cdc/207591/cdc_207591_DS1.pdf
• File Type:
  [PDF - 353.48 KB ]