Study On Technology And Economic Analysis Of Filling Repeated Mining In Strip Empty Area

There are a lot of coal pillars left in the narrow strip goaf in Northern Shaanxi.These pillars not only waste coal resources(the recovery rate of the mine is only about 30%),but also may lead to a series of disasters such as spontaneous combustion of coal seam and mine earthquake over time.In recent years,with the recovery of coal market and the exhaustion of some coal resources,the recovery of remaining coal pillars in goaf has been put on the agenda.In this paper,the feasibility of strip mined area recovery project in Changxing coal mine is demonstrated from two aspects of technology and economy.Based on the analysis of the geology and the current situation of the goaf in Changxing coal mine,the effective area method is used to calculate the coal pillar load in the goaf is 6.99MPa,and the solid coal uniaxial compressive strength is used to calculate the coal pillar stability coefficient is 1.93,which show the coal pillars are in a stable state.Taking 14 coal mines strip empty areas in Yuyang as samples,the stability evaluation model adapted to Yuyang District coal mine strip goaf was trained by BP neural network.Based on the evaluation model,,and the result that the 3107 working face goaf of Changxing coal mine is evaluated is stable.Through laboratory mechanical experiment of the coal sample in the goaf of 3107 working face,the average uniaxial compressive strength,modulus of elasticity,Poisson's ratio and uniaxial tensile strength of the coal pillar are 11.09MPa,884.8MPa,0.25 and 1.084MPa respectively.The mechanical experiment results are converted by the Hawke Brown failure criterion,and the minimum value of the in-situ strip coal pillar strength in the goaf is 10.52MPa and the stability coefficient of the coal pillar is 1.51,which further verifies that the goaf coal pillar is still in a stable state.Through the analysis of the load on the bearing body,the first scheme with large load is selected as the research object of numerical simulation.Based on this,the filling and recovery mining process is designed as the filling stage of the forward goaf,the even strip mining and filling stage of the backward type and the odd mining and filling stage of the backward type.The FLAC3D numerical simulation study on the filling and recovery mining process shows that the load on the support is less than its ultimate compressive strength during the entire filling repeated mining process,the bearing body and stope are in a stable state.The economic analysis shows that scheme ? and scheme ? are economically feasible,and the financial analysis shows that scheme ? has a shorter payback period and stronger profitability than scheme ?.Finally,scheme ? is selected as the stoping scheme of Changxing coal mine.The research results show that the bearing body and stope are in a safe and stable state during the process of filling and mining in Changxing coal mine.The project has low investment risk,short investment recovery period,high internal rate of return and good profitability.Therefore,the Changxing coal mine strip empty area filling recovery mining project is feasible,and can also provide a reference for mines with similar conditions.