U.S. flag An official website of the United States government.
Official websites use .gov

A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS

A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

i

Information Circular 9251: Frictional Ignition with Coal Mining Bits

Public Domain


Details

  • Personal Author:
    Courtney, Welby G.
  • Description:
    This publication reviews recent U.S. Bureau of Mines studies of frictional ignition of a methane-air environment by coal mining bits cutting into sandstone and the effectiveness of remedial techniques to reduce the likelihood of frictional ignition. Frictional ignition with a mining bit always involves a worn bit having a wear flat on the tip of the bit. The worn bit forms hot spots on the surface of the sandstone because of frictional abrasion. The hot spots then can ignite the methane-air environment. A small wear flat forms a small hot spot, which does not give ignition, while a large wear flat forms a large hot spot, which gives ignition. The likelihood of frictional ignition can be somewhat reduced by using a mushroom-shaped tungsten-carbide bit tip on the mining bit and by increasing the bit clearance angle; it can be significantly reduced by using a water spray nozzle in back of each bit, which is carefully oriented to direct the water spray onto the sandstone surface directly behind the bit and thereby cool the hot spots formed by the worn bit. A bit replacement schedule must be used to avoid the formation of a dangerously worn bit. [Description provided by NIOSH]
  • Subjects:
  • Series:
    Mining Publications
  • Subseries:
    Information Circular
  • Document Type:
    Text
  • Genre:
    Report
  • CIO:
    National Institute for Occupational Safety and Health (NIOSH)
  • Division:
    PRC - Pittsburgh Research Center
  • Topic:
    Workplace Safety & Health
  • Location:
    North America
  • Pages in Document:
    36 pdf pages
  • NIOSHTIC Number:
    nn:10007464
  • Federal Fiscal Year:
    1990
  • Peer Reviewed:
    False
  • Collection(s):
  • Main Document Checksum:
    urn:sha-512:ad34d55a5dd5201ce975474ee3f72938b24b5d5efd36f0ae1d00098d35f42b3696836a83bc04aee3a008d0a1912155f762add8190786164eb13affd37a87174a
  • Download URL:
  • File Type:
    Filetype[PDF - 2.63 MB ]
PREVIOUS
ON THIS PAGE
Details
CDC STACKS serves as an archival repository of CDC-published products including scientific findings, journal articles, guidelines, recommendations, or other public health information authored or co-authored by CDC or funded partners.

As a repository, CDC STACKS retains documents in their original published format to ensure public access to scientific information.
BACK TO TOP