Co-mining of mineral and geothermal resources: A state-of-the-art review and future perspectives

With the continuous increase in mining depths for mineral resources, the high-temperature thermal damage caused by deep earth temperatures has become a critical factor that restricts the safe and efficient mining of mineral resources. High-temperature environments directly affect the health of underground operators and reduce the service performance and lifetime of underground facilities and equipment. These high temperatures not only restrict mining efficiencies but also are a major safety hazard. However, the existing shaft facilities and abundant heat in the deep layers of mines provide favorable conditions for the large-scale development and utilization of geothermal energy. As clean and renewable energy, geothermal energy has significant advantages and great potential to reduce the cost of the deep mining of mineral resources. Making full use of geothermal energy stored in deep rock masses can not only effectively alleviate heat damage in mineral resource mining but also can promote the green, low-carbon, and sustainable development of the energy industry. To categorize mineral resources that may be associated with geothermal resources, here, we review and summarize existing mineral–geothermal co-mining technologies, i.e., the mine water source heat pump system, high-temperature exchange machinery system, deep salt mine geothermal extraction system, and oil and gas field geothermal energy comprehensive utilization project. Future modes, i.e., co-mining based on a brine circulation system, excavation technology, the filling mining method, in situ leaching method, and reuse of abandoned mines, are also analyzed. Moreover, the main challenges faced during the co-mining are discussed, including strengthening the exploration of the co-mining areas with mineral–thermal resources, developing rock breaking and tunneling technology for deep high-temperature hard rocks, strengthening the theoretical and experimental research of deep multifield coupled environmental rock mechanics, and establishing a graded utilization system of thermal energy for the co-mining of mineral–thermal resources. These research results are aimed at promoting geothermal energy development in the mining of mineral resources to benefit the large-scale utilization of geothermal resources and can provide a useful reference for the mining of deep mineral resources and the development of geothermal resources in China. Furthermore, promoting mineral–geothermal co-mining can promote the development of China’s deep resources to achieve the double carbon goal of “carbon peaking and carbon neutralization.”