Collaborative mining system of geothermal energy and coal resources in deep mines

Coal resources are non-renewable one-time energy. With the increase in mining depth, thermal energy is released with the exploitation of deep coal resources. It is renewable and clean, unaffected by environmental factors, and is an important part of geothermal resources. The Chinese government attaches great importance to and encourages the development and utilization of clean energy. Therefore, this paper summarizes the development potential of geothermal resources in deep mines and the current situation of geotherm and coal mining, discusses the necessity and feasibility of geothermal development in deep mines, innovates a collaborative mining of geothermal energy and coal resources, and expounds the scientific and technical problems of the coordinated development of geothermal and coal resources in mines. The scientific problems primarily include the distribution characteristics and the supply law of geothermal sources in deep mines, the law of energy conduction and evolution in stopes, and the heat and mass transfer mechanism of low-grade geothermal energy. The technical problems mainly include the optimization method of the system for the coordinated development of geothermal and coal resources in deep mines, the method for the coordinated development of geothermal and coal resources in deep mines, etc. Focusing on the theme of the development of rock heat and hydrothermal resources in deep mines and considering the post-mining space and production system, this paper introduces four heat recovery methods: buried pipe heat recovery method in the backfilled stopes, water storage and heat recovery method in the goaf, heat recovery method in the closed fracture and caving zones, and in-situ drilling for the heat recovery method in deep aquifers. Keys and difficulties of this paper include the detection and evaluation of geothermal energy in deep mines, heat-absorbing functional materials of coal-based solid waste in deep and large spaces, the characteristics and controlling methods of the rock stratum movement in a multi-field environment in mine stopes, efficient transmission and stepped utilization system of low-grade heat energy, and the intelligent monitoring of geothermal energy and coal collaborative mining system. The results of this paper will provide technical support for the collaborative mining of geothermal energy and coal resources in deep mines in China, as well as provide a theoretical and practical reference for the development of a deep mine resources system in China and promote the construction of green mines and multi-economic development of deep mines in China.