Recent results of dust explosion studies at the Lake Lynn experimental mine.
Weiss-ES; Greninger-NB; Sapko-MJ
Proceedings of the 23rd International Conference of Safety in Mines Research Institutes, September 11-15, 1989, Washington, DC. Washington, DC: U.S. Bureau of Mines, OFR 27-89, 1989 Sep; :843-856
The U.S. Bureau of Mines, as part of its continuing research program for evaluating coal dust explosion hazards, has recently completed a series of tests in the Lake Lynn experimental mine (LLEM) to study the effect of entry size on the flammability limits of pure coal and coal dust/rock dust mixtures. Data will be presented that compare measurements from explosions of mixtures of coal dust, methane, and rock dust. There are significant differences in dust explosion propagation characteristics between the LLEM and the smaller entry Bruceton experimental mine (BEM). The larger entry (LLEM) results indicate a larger rock dust percentage is required to prevent flame propagation than in the BEM. Lower flammable limits of coarse and fine Pittsburgh seam coal dusts were obtained in the LLEM. A lower volatile minesize coal required about 40 pct total incombustible content (TIC) to prevent propagation in previous BEM experiments, whereas, recent tests with a similar volatile (18 pct) Pocahontas seam mine-size coal required 60 pct TIC in the larger entry of the LLEM to prevent flame propagation. As one means of preventing these coal dust explosions, 80-L water tub barrier units were tested in the larger entry of the LLEM. The relative efficiencies of roof-mounted and rib-stacked barriers were determined for suppressing fully developed coal dust explosions in a single entry. Barrier sets were evaluated at various locations (40 to 160 m from the face) and configurations in the entry. Units were suspended near the roof and triply stacked at the ribs. Stacked barrier units which are portable, simple to install, and inexpensive to erect provided protection against coal dust explosions in the LLEM. In wide mine entries, they pose less of an impedance problem for men and equipment than do roof-mounted barriers. For some mines having high dust deposition rates, stacked barriers would offer additional protection beyond that afforded by generalized rock dusting.
Mining; Mining industry; Underground mines; Underground mining; Coal mines; Coal mining; Explosion prevention; Explosions; Explosive dusts; Coal dust; Rock dusting; Flame propagation
OP; Conference/Symposia Proceedings
NTIS Accession No.
Proceedings of the 23rd International Conference of Safety in Mines Research Institutes, September 11-15, 1989, Washington, DC