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In view of high ground stress, high geothermal temperature, and thermal hazard during deep mineral resource exploitation, the concept of phase-change heat storage backfill was put forward in this study. Further, the corresponding technical system was constructed and the main content involved in technical system, which is the optimized proportion of the backfill slurry added with phase-change materials (PCMs), was examined. Moreover, we elaborated upon the collaborative optimization of a backfill body’s mechanical and thermal properties and the mutual cooperation on backfill mining, geothermal energy exploitation, and simultaneous stope cooling. The heat transfer behavior of a backfill body plays a key role in technology system. We numerically simulated the heat transfer among a backfill body, surrounding rock, and airflow in the heat storage process, as well as the heat transfer between backfill body and cold fluid during the heat release process. The temperature distribution of a backfill body at different heat storage/heat release times—i.e., the temperature distribution and its evolution—with heat transfer were revealed and analyzed. This study can provide theoretical guidance for a phase-change heat storage backfill, as it has an important significance for the collaborative exploitation of mineral resources and geothermal energy.

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The underground mine contains abundant geothermal energy resources. The casing-type mine heat recovery device with encapsulated phase change material (PCM) embedded in the backfill body is efficient technology for extraction of geothermal energy in mines. A heat transfer model of a casing-type mine heat recovery unit was established to study the influence of PCMs thermophysical property and phase transition process on the thermal performance of backfill body. The effects of phase transition temperature, thermal conductivity, specific heat capacity and phase transition latent heat of PCMs on the temperature variation in backfill body and the thermal performance of casing-type mine heat recovery device were studied in the heat storage/release mode. The result indicates that the phase transition temperature is expected to be lower in heat storage mode and higher in heat release mode, respectively. The heat transfer rate

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