Research on Joint Protection Layers and Gas Prevention Technology in Outburst Coal Seams

Abstract

Outburst closed distance coal seam distances are extremely difficult to mine, and are commonly involved in safety accidents in the process of mining. Based on the engineering background of the Wulan Coal Mine at the western margin of the Ordos Basin, this paper presents a theoretical analysis, engineering analogies, and numerical simulations to determine the optimal mining sequence for the Wulan Coal Mine #7, #8, #2, and #3 coal seams. Floor penetration drilling was used to eliminate outbursts in the #7 and #8 coal seams, and gas control in the #2 and #3 coal seams was achieved using ground drilling to pump and release the pressured gas. We established a comprehensive management technology system for gas emissions from the short-distance joint protection layer in the outburst coal seams of Wulan Coal Mine, where pressure relief and drainage were carried out by drilling through the floor and surface drilling pressure relief extraction. Through field tests, the pre-drainage rate of the #2 coal seam in the Wulan Coal Mine was 66.8%, and the pre-drainage rate of the #3 coal seam was 68.1%. This shows that protective layer mining of the #7 and #8 coal seams combined with surface drilling to extract pressure-relief gas can protect the #2 and #3 coal seams.