Practice on Mining Extremely Thin Protective Seam of II_1 Coal Seam with Drilling Exploit Technology

In order to eliminate the coal-gas outburst danger in the exploiting process of Ⅱ1 coal seam in Cuimiao Coal Mine,the extremely thin coal seam(Ⅰ9)under Ⅱ1 coal seam was exploited by using drilling exploit technology.The pressure relief and expansion of Ⅱ1 coal seam was achieved,the effective desorption of gas in Ⅱ1 coal seam was realized,the liquidity of gas in coal seam also was enhanced.Based on this,through the arrangement of drilling field in the floor of Ⅱ1 coal seam and gas drainage,the gas content in coal seam significantly decreased and gas pressure went down obviously.The Ⅱ1 coal seam changed from high gas outburst coal seam into a low gas outburst and non-risk coal seam,and met with the requirements of highly efficient and high-yield production in the protective seam working face.