Medium Pressure Compressed Air Drilling Technique and Matched Equipment in Soft and Outburst Seam

The soft and outburst seam would be poor in stability,high in gas content and high in pressure and would be easy to occur the borehole outburst,borehole collapsed,drilling jammed and other abnormal phenomenon.Thus the drilling operation and borehole completed in such seam were the general difficulty.In China,the screw drilling and the normal pressure compressed air drilling were conducted for trial and the results were not so good.A medium pressure compressed air drilling exploration was provided to apply to the construction of the gas drainage boreholes in the soft and outburst seam.A set of the borehole protection method was designed.A marched drilling rig,core detachable bit,borehole dust collector and other equipment were researched and developed.The mine site industrial experiment of the technique was passed and showed that the technique was feasible and the matched equipment was reliable.