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Abstract In view of the low permeability coefficient and high gas content of No. 8 coal seam in Xiegou Coal Mine, the traditional gas control method leads to the poor effect of gas extraction in this coal seam. The ultra-high pressure hydraulic slotting pressure relief and permeability enhancement technology was tested in 18205 belt roadway. The optimal parameters of ultra-high pressure hydraulic slotting pressure relief and permeability enhancement for No. 8 coal seam in Xiegou Coal Mine were obtained by using the control variable method. The slotting pressure, slotting time, slotting speed and slotting spacing were 60 - 70 MPa, 25 min, 80 r/min and 2 m, respectively. By analyzing and comparing the ordinary drilling and slotted drilling, it is found that the extraction concentration of slotted drilling is 1.75 times that of the ordinary drilling, and the extraction purity is 3.25 times that of the ordinary drilling. The gas extraction time is reduced by 42%, and the residual gas content in coal seam is significantly reduced, and the gas extraction effect is significantly improved.
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