Analysis study on selective preference of recovery mining project for island-like working face

Island working face is a technical problem of coal mining in China,strong ground pressure behavior is significant characteristic of island working face,the island-like working face in Xiashijie Coal Mine stopped mining and closed working face due to strong mining pressure behavior. In order to realize the beneficial recycling of resources,extend the remaining service life of the mine,and realize the safe re-mining of the island-like working face,on the basis of comprehensive site survey,numerical simulation calculation and theoretical analysis,this paper summarizes and analyzes the dynamic pressure behavior characteristics and its mechanism of No.220 working face,and puts forward two kinds of transformation schemes of No.220 working face expansion and contraction.The results show that the dynamic pressure behavior of No.220 working face is closely related to periodic roof weighting and roof activity,and the comprehensive effects of super-high stress,upper multi-layer thick and hard rock,wide coal pillar and frequent coal blasting are the root of strong mining pressure behavior. The optimal re-mining schemes is determined as expanding face reconstruction(15 m in internal displacement Goaf 2301) and reducing face reconstruction(shorten by 50 m). By comprehensively comparing the overall risks and economic benefits of the two mining schemes,it is suggested that the fully mechanized top coal caving mining should be carried out in the No.220 working face with a reduced face of 50 m,and a simple machine head and a single motor at the tail should be installed,and whether to replace the transition support and install the regular machine head and electric machine should be decided according to the situation.