A Novel Longwall Mining Layout Approach for Extraction of Deep Coal Deposits

As more easily mined deposits are depleted, the reserves are becoming more limited and less favorable. Deposits of coal or trona that are being longwall mined are deep and are getting deeper. Coal bursts and bumps frequently occur within development entries in longwall mining of deep mines due to high stresses. This paper presents a novel patented longwall mining layout “Longwall Mining with Split-level Gate roads (LMSG)” that has the potential to mitigate several problems related to deep mining (Patent No. ZL98100544.6). LMSG locates gate roads on either end of a longwall panel at different vertical heights within a coal seam or in a geologically split seam, so that the two adjacent panels can be partially offset horizontally. It is novel in that it incorporates unit operations of different mining methods into the system. By employing multiple slice longwall mining method locally at the face ends, and adjacent panels overlapping end to end, pillar-less longwall mining can be achieved to mine deep deposits. A conventional rectangular gate road pillar is therefore transformed into a small triangular pillar and the gate road of the subsequent panel can be located along or under the gob of the previously mined panel where the stresses are lower. Several mines in China and Russia are currently using the technology with reduced incidence of ground control problems. Through theoretical analysis, and physical and numerical modeling approaches, it is demonstrated that LMSG significantly improves stress environment for development entries, with associated reduction in coal bursts and ground control problems.