Research progress on the prevention and utilization of mine geothermal energy

Abstract

The gradual increase in mining depth will inevitably lead to several problems because of mine geothermal energy. However, although mine geothermal energy poses dangers such as high temperature and heat hazards, it is also a resource that can be developed and utilized. Based on the existing research results, this paper first summarized the disaster-causing forms of mine geothermal energy. Then, the current prevention and control technologies of mine heat hazards were reviewed. Finally, the main utilization methods of mine geothermal energy were summarized. The findings show that the forms of disasters caused by mine geothermal energy can be classified into three types: aggravating the deterioration of coal and rock mass, inducing the failure of supporting structures, and creating high-temperature and high-humidity environments, including aggravating the deformation and failure of surrounding rock, inducing adsorption gas overflow, reducing the anchor pullout force, aggravating the corrosion of the anchor structure, damaging workers’ physical and mental health, reducing the labor efficiency of workers and machines, and increasing the failure rate of machinery and equipment. Two types of heat hazard control technologies are used: artificial and non-artificial cooling technologies. Non-artificial cooling technology can be divided into three categories: heat source control technology, heat-humidity environment control technology, and individual protection technology. According to various refrigerants, an artificial cooling system can be divided into three categories: air-cooled, ice-cooled, and water-cooled, including compressed air refrigeration cooling systems, ice-cooling systems, ground centralized refrigeration cooling systems, surface heat dissipation, underground centralized refrigeration cooling systems, return air exhaust heating underground centralized refrigeration cooling systems, ground cogeneration refrigeration cooling systems, and resource utilization of heat-harm systems. Extracting waste heat from mine water and mine return air for defreezing of the mine head, bath heating, and building heating is the main method for using mine geothermal energy at present, which can effectively reduce the consumption of primary energy at the same time; thus, it is of great significance for promoting green mining and sustainable development of coal mines. Using a buried tube heat exchanger to extract thermal energy from surrounding rock and realizing the coordinated use of several types of clean energy in a mining area is a future development direction for mine geothermal energy use. By drilling holes in the surrounding rock of a coal mine roadway, the buried pipe heat exchanger is arranged in the surrounding rock of the roadway, and water or organic matter is used as a heat exchange medium. The geothermal energy of roadway surrounding rock is extracted using ground source heat pump technology. In addition, for mining areas with excellent lighting conditions or sufficient wind energy, wind power generation and photovoltaic power generation/heat collection can be used simultaneously, and the produced electric energy and thermal energy can be directly used by users and for water pumps, heat pump units, and so on. The results of this paper provide a reference for mine heat hazard control and resource utilization in our country.

Keywords

• mine geothermal
• mine heat hazard
• cooling system
• thermal energy utilization
• high temperature and high humidity