Processes | Free FullText | Design and Optimization of a Novel ... MDPI
Inseam drilling is often adopted for gas predrainage in coal and gas outburst mines [1,2,3,4].Because hydraulic slag removal is used in wet drilling, soft coal absorbs water and expands, causing drill holes to collapse [5,6,7,8] and reducing the penetration, dry drilling and slag removal by wind are the main operational methods for gas predrainage of underground soft coal ...