[Federal Register Volume 74, Number 161 (Friday, August 21, 2009)]
[Notices]
[Pages 42317-42318]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-20205]
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DEPARTMENT OF HEALTH AND HUMAN SERVICES
Centers for Disease Control and Prevention
[Docket Number NIOSH-174]
Recent Coal Dust Particle Size Surveys and the Implications for
Mine Explosions
AGENCY: National Institute for Occupational Safety and Health (NIOSH)
of the Centers for Disease Control and Prevention (CDC), Department of
Health and Human Services (HHS).
ACTION: Notice of draft publication available for public comment.
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SUMMARY: The National Institute for Occupational Safety and Health
(NIOSH) of the Centers for Disease Control and Prevention (CDC)
announces the following draft Publication available for public comment
entitled ``Recent Coal Dust Particle Size Surveys and the Implications
for Mine Explosions.'' The document and instructions for submitting
comments can be found at http://www.cdc.gov/niosh/review/public/174/default.html.
Public Comment Period: Comment period from August 31, 2009 to
September 30, 2009.
ADDRESSES: Written comments may be submitted to the NIOSH Docket
Office, Robert A. Taft Laboratories, 4676 Columbia Parkway, MS-C34,
Cincinnati, Ohio 45226. All material submitted to the NIOSH should
reference docket number NIOSH-174 and must be submitted by September
30, 2009 to be considered by the Agency. All electronic comments should
be formatted as Microsoft Word. In addition, comments may be sent via
e-mail to [email protected] or by facsimile to (513) 533-8285. A
complete electronic docket containing all comments submitted will be
available on the NIOSH Web page at http://www.cdc.gov/niosh/docket, and
comments will be available in writing by request. NIOSH includes all
comments received without change in the electronic docket, including
any personal information. All information received in response to this
notice will be available for public examination and copying at the
NIOSH Docket Office, Room 111, 4676 Columbia Parkway, Cincinnati, Ohio
45226, telephone (513) 533-8611.
Background: Spreading rock dust in bituminous coal mines is the
primary means of reducing the explosion potential of coal dust that
collects during the normal workings of an active coal mine.
Accordingly, guidelines have been established by the Mine Safety and
Health Administration (MSHA) about the relative proportion of rock dust
that needs to be present in both intake and return airways.
Specifically, current MSHA regulations require that intake airways
contain at least 65% incombustible content and return airways contain
at least 80%. The higher limit for return airways was set in large part
because fine ``float'' coal dust (100% < 200 mesh or 75 [mu]m) tends to
collect in these airways. MSHA inspectors routinely monitor rock dust
inerting efforts by collecting dust samples and measuring the
percentage of total incombustible content (TIC). These regulations were
based on two important findings: a survey of coal dust particle size
that was performed in the 1920s and large-scale explosion tests
conducted in the U.S. Bureau of Mines' Bruceton Experimental Mine (BEM)
using dust particles of that size range to determine the amount of
inerting material required to prevent explosion propagation.
Mining technology and practices have changed considerably since the
1920s when the original coal dust particle survey was performed. Also,
it has been shown conclusively that as the average size of coal dust
particles decreases, the explosion hazard increases. Given these
factors, the National Institute for Occupational Safety and Health
(NIOSH) and MSHA conducted a joint survey to determine the range of
coal particle sizes found in dust samples collected from intake and
return airways of U.S. coal mines. Results from this survey show that
the coal dust found in mines today is much finer than in mines of the
1920s, presumably due to increased automation and a greater reliance on
mining machinery.
In light of this recent comprehensive dust survey, NIOSH conducted
additional large-scale explosion tests at the Lake Lynn Experimental
Mine (LLEM) to determine the degree of rock dusting necessary to abate
explosions using Pittsburgh seam coal dust blended as 38% < 200 mesh
and referred to as medium-sized dust. Explosion tests indicate that
medium-sized coal dust required 76.4% TIC to prevent explosion
propagation. Even the coarse coal dust (20% < 200 mesh or 75 [mu]m)
representative of samples obtained from mines in the 1920s required
approximately 68% TIC to be rendered inert, a level higher than the
current regulation of 65% TIC. In return airways, the particle size
survey revealed that the average dust particle size is roughly the same
as float coal
[[Page 42318]]
dust as defined in the Coal Mine Health and Safety Act of 1969.
Given the results of the recent coal dust particle size survey and
large-scale explosion tests, NIOSH recommends a new standard of 80% TIC
be required in the intake airways of bituminous coal mines. The survey
results indicate that the current requirement of 80% TIC in return
airways is still sufficient and appropriate. In addition, NIOSH agrees
with and endorses an earlier recommendation that new rock dusting
standards should be based on a worst-case scenario (using high volatile
coals) with no relaxation for lower volatile coals.
FOR FURTHER INFORMATION CONTACT: Dr. Jeff Kohler, NIOSH Associate
Director for Mining and Construction, 626 Cochrans Mill Road,
Pittsburgh, PA 15236, (412) 386-6544, E-mail [email protected].
Reference: Web address for this publication: http://www.cdc.gov/niosh/review/public/174/pdfs/RD-inertingOutToExtReview.pdf.
Dated: August 14, 2009.
Christine M. Branche,
Acting Director, National Institute for Occupational Safety and Health,
Centers for Disease Control and Prevention.
[FR Doc. E9-20205 Filed 8-20-09; 8:45 am]
BILLING CODE 4163-19-P