ABSTRACT
Based on the theory of two phase flow, theoretical questions of pneumatic conveying of drill-chips from along bedding drilling in outburstable coal seams were studied. The calculate on formulas of the minimum air speed for pneumatic conveying and the total pressure loss were derived. Influence of factors, such as the drill-hole diameter, drill pipe diameter, drilling velocity, inner hole diameter of drill pipe, and outburst danger degree on the minimum air speed and the total pressure loss was analyzed. According to these conclusions, some drilling parameters were designed. In Qinan Coalmine, some drilling holes of more than 80 m in length, are drilled successfully in outburstable coal seam.
