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Overview of NIOSH's mine seal research.

Sapko-MJ; Weiss-ES; Cashdollar-KL; Greninger-NB
28th International Conference of Safety in Mines Research Institutes, Sinaia, Romania, June 7-11, 1999. Pterosani, Romania: National Institute for Mining Safety and Explosion Proof Protection, 1999 Jun; 1:71-85
Within the last 4 years, seven documented explosions of methane and/or coal dust occurred within sealed areas of underground U.S. coal mines. These explosions, believed to be initiated by lightning strikes on the surface, destroyed numerous seals and caused considerable damage external to the sealed area. Fortunately, these explosions did not cause fatalities or injuries. However, the potential for a disaster still exists, emphasizing the need for explosion resistant seals that can perform under various mining conditions. The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) has conducted full-scale explosion experiments to evaluate the strength characteristics of several seal designs for isolating worked out areas in underground coal mines. Full-scale seals (11 to 16 m2 in cross-section) were constructed in the multiple entry section of the Lake Lynn Laboratory experimental mine and exposed to a series of methane and coal dust explosions with overpressures ranging from 120 to 595 kPa. Seals were fabricated with various strength cementitious-type materials ranging in thickness from 0.175 to 1.2 m. High-strength cementitious seal designs made with a reinforced steel matrix were also evaluated as well as rapid setting designs capable of withstanding 138 kPa overpressures only 27 hours after construction. A novel seal design employing concrete block and a pre-loading technique with no recessing shows promise as an alternative to the D.S: Code of Federal Regulations (CFR) standard-type solid concrete block seal design which is recessed into the ribs and floor. This new seal design is capable of withstanding 138 kPa and is of particular interest to mine operations that have weak or friable ribs where conventional sealing techniques are not adequate. Also included is a discussion of PRL's recent efforts to design and construct large test chambers (15 and 42 square meters in cross section) for the pneumatic and hydrostatic evaluation of seals, as an alternative to full-scale explosion testing.
Mining-industry; Ergonomics; Case-studies; Statistical-analysis; Fire-prevention; Disaster-prevention; Explosion-damage; Explosion-prevention; Explosion-protection; Explosive-atmospheres; Explosive-dusts; Explosive-hazards; Injuries; Injury-prevention; Traumatic-injuries; Quality-control; Quality-standards; Mine-seals; Mining-equipment; Underground-mining
NIOSH Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, PA 15236
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28th International Conference of Safety in Mines Research Institutes, Sinaia, Romania, June 7-11, 1999