§864 Combustible Materials and Rock Dusting

Summary

Mine operators must keep coal dust, loose coal, and other burnable materials cleaned up so they do not build up in working areas or on electrical gear underground. If mining makes too much dust, water, water with a wetting agent, or another approved method must be used to control it. In work areas, especially within 40 feet of the face, water or an approved method must be applied to the ribs, roof, and floor to cut down dust spread and reduce explosion risk. All underground areas must be rock-dusted up to 40 feet of working faces (and crosscuts under 40 feet), unless the area is too wet, too noncombustible, unsafe, or the Secretary or their representative says an exception is allowed. Rock dust must cover tops, floors, and sides so the combined dust has at least 65% incombustible content (80% in return airways). If methane is in any ventilating air, increase those percentages: add 1.0 percentage point for every 0.1% methane where 65% is required, and add 0.4 percentage point for every 0.1% methane where 80% is required. The rules about wetting and rock dusting do not apply to underground anthracite mines.