captage du grisou

CONT: Le captage du grisou est réalisé en creusant de longs trous, soit à partir de la surface, soit à partir des galeries de reconnaissance du gisement, en direction des couches de charbon. Le gaz ainsi récupéré, principalement du méthane, est utilisé comme combustible; en outre, l'exploitation ultérieure du gisement est facilitée par la réduction des dégagements du grisou dans les galeries et chantiers.

CONT: Three main systems of methane drainage have been developed: (1) the cross-measure borehole method which consists of boring holes from 2¼ to 3¼ inches in diameter and 150 to 300 feet in length, into the strata above or below the seam, generally close to the working face. This method has the advantage of being suited to a wide variety of conditions and does not require another seam within reasonable distance above or below the seam to be drained, or the use of solid stowing; (2) the superjacent roadway system in which boreholes are drilled from a roadway situated above the seam being worked, the drainage of the methane then taking place from this roadway; and (3) the pack cavity system in which corridors are left and supported in the goaf as the face advances, and from these firedamp is drawn off.