Safe strategy for coal and gas outburst prevention in deep-and-thick coal seams using a soft rock protective layer mining

Abstract

Coal and gas outburst is one of the most harmful disasters in coal mine production. With the increase of mining depth, all the coal seams in the deep-and-thick coal seam group will be upgraded to outburst coal seams, resulting in no suitable first mining layer can be selected as the protective layer. In this case, coal and gas outburst disasters are more serious and outburst prevention and control is more difficult. In order to alleviate the gas disaster and eliminate the risk of gas outburst, a safe strategy was proposed in this study. In this strategy, a suitable soft rock layer adjacent to deep-and-thick coal seams in the Luling coal mine of Huaibei coalfield was selected as the first protective mining layer after safety, economic and technical feasibility argument. Meanwhile, the stereoscopic gas extraction and utilization system safety engineering was established. The effect in the mining process practice of the soft rock protective layer was investigated and verified. Practice shows that this safe strategy can effectively reduce the outburst risk of strong outburst deep-and-thick coal seams and a large amount of pressure relief gas can be extracted and utilized. It can provide a new safety idea for efficient exploitation of coal and gas resources in deep-and-thick coal seams in China.