Exploration on the method of ore deposit geothermal energy synergetic mining in deep backfill mines

In order to reduce the backfill cost of deep mines,alleviate the heat hazard and realize the economic and effective exploitation of deep ore deposit and geothermal energy,a method named Ore Deposit Geothermal Energy Synergetic Mining (OD-GESM) is put forward.Based on the academic concept of functional backfill in mines,the method,combining mine backfill,heat hazard control and geothermal mining,can transform heat hazards in mines into geothermal energy commodities to offset the backfill cost and cooling cost using a buried pipe heat extraction technology.The overall scheme and synergetic system of OD-GESM are constructed and three basic synergetic modes,i.e.,ore geothermal mining,stope cooling geothermal mining,and backfill body curing geothermal mining are proposed,so as to realize synchronous geothermal energy exploitation in the process of controlling mine heat hazard or mining deep ore deposits.Taking the Upwards Cut fill Mining Method as an example,the basic synergistic principle and mechanism among the three subsystems of ore deposit mining,goaf backfill and geothermal mining are elaborated in four aspects of time,space,environment and technology,to give a full play to their synergistic effect in different stages,improve mining efficiency and reduce mining cost.In theory,a three dimensional numerical model for the heat transfer of buried pipe backfill body and an evaluation model of geothermal resources are constructed,giving the key governing equations and evaluation indexes of geothermal resources in the heat extraction stage and the heat recovery stage.The results show that when the surrounding rock temperature is 45 ℃,the backfill stope with the size of 3 000 m×20 m×105 m can continuously provide the heat energy of 15.0-17.5 ℃ to the heat pump system with the power of 257.8-377.2 kW for 5.6 months each year,a total of 1.2 GW·h.The heat pump system can efficiently and stably produce hot water at 50 ℃ in cold winter to heat an office building of 4 600-6 855 m2.The application of OD-GESM technology in the deep backfill mines has realized the organic integration of deep mining,goaf treatment,solid waste disposal and renewable geothermal energy exploitation.