The Application of a Novelgas Drainage Technology for Lower Protected Coal Seams in the Xinzhuangzicoalmine, Huainan Coalfield, China

Abstract

There is a growing concern on protective seam mining tore lieve coal and gas out burstin coal seam group mining. For upper protective seam mining, the effect of pressure relief and permeability increase in lower protected seams is determined by the distance between upper protective seams and lower protected seams (which is stronger at shorter distances). However, more relief gas flows to the working faces of protective seams at shorter distances, making gas control of the working faces more difficult. In this study, taking working face 62114 of the Xinzhuangzimine, Huainan as the engineering background, the gas emission laws of the working faces of the upper protective seams in close range are analyzed, and gas control measures are proposed. Furthermore, the gas extraction results of the close range mining face on the upper protective seam are analyzed. The results show that① with the implementation of the protective seam mining, in the mining influence area, the underlying rock strata can be divided into floor heave fracture zone and floor heave deformation zone, and gas from the lower protected seams in the floor heave fracture zone tends to migrate to the protective seam goaf; ② Y-ventilation can be used to solve gas accumulation and gas overflow in the upper corner at the mining face of close range upper protective seams; ③ in principle, the penetrating borehole spacing of lower protected seams should be less than or equal to the seam spacing in order to effectively prevent flows of releasing gas of protected seams into the working face of protective seams.