An Innovative Longwall Mining Technology in Tangshan Coal Mine, China

In mining of inclined coal seams in Tangshan coal mine of Kailuan group, gateways on either end of a panel were both typically located along the floor and a gateway pillar between adjoining panels was left unmined between adjacent panels to ensure stability, thus forming a planar mining system. According to the practice, however, it turned out that this conventional mining system has long-standing problems, such as face end support problems, coal bumps, sliding of mining equipment downhill, spontaneous combustions, support problems in development entries, etc. In view of this situation and based on the No. Y294 panel, this paper analyzes an innovative mining technology in which the gateways on either end of a panel are located at different heights within the coal seam. For the adjacent panel, the gate development may be superposed on the development entry of the previous panel or may be offset with respect to it. Field data shows that the split-level layout of the longwall panel plays an effective role in control of overall stability of mining equipment in inclined coal seams. Physical modeling demonstrates that the new technology has many advantages in ground control. Under the condition without a pillar, development entry adjacent to the new panel is located in the de-stressed zone and stress concentration is significantly reduced with associated reduction in coal bumps, bursts and support problems which means less support and maintenance requirement and cost. Compared with the conventional rectangular pillar, the gateway pillar width in this new technology is effectively reduced when pillars have to be left unmined. Roof strata behavior and features are analyzed. Corresponding operations in the field are introduced in detail.