Reasonable top coal drawing rounds in horizontal section top-coal caving mining of Wudong Coal Mine

ZHANG Chunlei; WAN Xiaohang; ZHANG Jinwang; WEI Weijie

doi:10.11799/ce202505002

Abstract：The+443 m B3-6 working face of Wudong Coal Mine is a horizontal section fully-mechanized caving face in nearly vertical extra-thick coal seam.In order to improve the top coal recovery rate and mining efficiency of fully-mechanized caving face,the top coal migration characteristics of+443 m B3-6 working face in Wudong Coal Mine under different caving rounds were studied and analyzed by means of theoretical analysis and numerical simulation.The results show that the use of multiple rounds of coal caving can reduce the height of coal caving,make the coal-rock interface formed after coal caving move down gently,weaken the lagging development characteristics of the coal-rock interface in the middle of the working face,and promote the expanding of tangent range between the caving body and the coal-rock interface,so as to improve the top coal recovery rate in the middle of the working face.With the increase of the number of coal caving rounds,the position where the coal-rock interface begins to lag behind delays;compared with single round caving,the residual coal in the middle of the working face is greatly reduced when three or more rounds are used.Multi-round coal caving can significantly reduce the amount of residual coal on the roof side of the working face,which can reduce more than 50%of the residual coal on the roof side compared with single-round coal caving.For the recovery rate of top coal,multiple rounds of coal caving can improve the recovery rate of even-number supports,and with the increase of the number of coal caving rounds,the recovery rate of even-number supports of top coal increases gradually;the overall recovery rate of the working face increases first and then decreases with the increase of coal drawing rounds.Based on the comprehensive theoretical analysis,numerical simulation and on-site construction,the+443 m B3-6 working face of Wudong Coal Mine should choose the three-round interval coal caving process to improve the top coal recovery rate.Compared with the single-round interval coal caving,the top coal recovery rate can be increased by more than 2%.