Control of methane in gobs and bleeders by the cross-measure borehole technique.
Proceedings of the 14th Annual Institute on Coal Mining Health, Safety and Research, Blacksburg, Virginia, August 23-25, 1983. Karmis M, Patrick JL, Sutherland WH, Lucas JR, Faulkner G, eds., Blacksburg, VA: Virginia Polytechnic Institute and State University, 1983 Aug; :139-148
Methane in longwall gobs is controlled in Europe and Great Britain during mining by drilling small-diameter holes into the roof strata (cross-measure boreholes) from underground locations and applying suction to each hole to draw the methane from the roof strata when fractured. Holes are connected to an underground pipeline which transports the gob gas (methane plus air) to the surface. Table 1 clearly demonstrates the importance of gob gas control during mining in Europe. The total length of cross-measure boreholes drilled in 1975 ranged from 117 miles in West Germany to 162 miles in Czechoslovakia. In Poland and Czechoslovakia, 90 pct or more of the drained gob gas is utilized, and 54 pct is used in West Germany. The gob gas, which averages 60 pct methane, is used for steam and power generation, for driers in coal preparation plants, and for steel production. Prior to 1970, ventilation was the primary method of controlling methane in gobs in the United States. As mining depth increased, gassier coal beds and surrounding strata were encountered, and acceptable methane levels in the bleeders could not be maintained by ventilation alone. Consequently, surface gob boreholes were introduced in the 1970's as an auxiliary gob gas control method. The method proved highly effective and is commonly used today by the mining industry. Surface gob boreholes cannot always be drilled because mining may be under populated areas, topography may be too severe, or access to private property may be denied. An alternative method of controlling gob gas is needed that is independent of the mine ventilation system and surface right-of-way problems. The cross-measure borehole technique appears to satisfy these criteria.
Mineral-processing; Mining-industry; Coal-mining; Longwall-mining; Underground-mining; Room-and-pillar-mining; Mine-gases; Methanes; Methane-drainage; Methane-control; Explosive-gases; Explosive-atmospheres; Control-technology; Engineering-controls; Ventilation; Ventilation-systems
Karmis-M; Patrick-JL; Sutherland-WH; Lucas-JR; Faulkner-G
Proceedings of the 14th Annual Institute on Coal Mining Health, Safety and Research, Blacksburg, Virginia, August 23-25, 1983