Effect of hydrogeological conditions on the mining sequence in Menkeqing Mine

The hydrogeological type of Menkeqing Mine is of complex type, when the production started, working face was designed and arranged respectively in seams 3^-1 and 2^-2. The average distance between two seams is 34 m. During extraction of both seams, the major water-filling aquifer was Qilizhen sandstone aquifer at the bottom of Zhiluo Formation. The pressure of the aquifer was high, up to 4 MPa, the maximum water inflow of a single drainage hole reached 180 m³/h, the water abundance was relatively high, and the distance of the aquifer was mostly less 5 m from seam 2^-2, inducing serious water drops from the roof in during driving in coal roadway of seam 2^-2 and difficulties for cable bolt, the safe production in seam 2^-2 could not be ensured. The authors proposed a mining method with reverse sequence, that is, seam 3^-1 was mined firstly, and when the water yield and pressure dropped enough to ensure smooth driving and extraction in seam 2^-2, the upper seam 2^-2 was mined. The mining practice demonstrated that the scheme was feasible.