Medium Pneumatic Pressure Drilling Technique in Complicated Soft Seam

According to the difficult borehole drilling status for the coal seam gas drainage in the soft seam of Qinan Mine,the ZDY-3200L drilling rig and related equipment were applied to the medium pneumatic pressure drilling technical test with the self-made borehole entry dust collector,gas and cutting collection integrated device.With the above measures,the average depth of the borehole drilled could reach to 127.9 m.The gas drainage volume fraction could reach to 30%~40%,which could effectively solve the dust problems in the borehole drilling and ensure the safety production of the coal mining face.