Gold tailings-solar salt shape-stabilized phase change materials for medium-high temperature thermal energy storage

Gold tailings (GT) are a form of industrial solid waste generated by gold production that occupy large areas of land and cause a significant environmental burden. This study accordingly prepared a novel composite phase change material (CPCM) for medium-high temperature thermal energy storage using a hybrid sintering method to combine GT as the base material with solar salt (SS) as the phase change material. The resulting gold tailings composite phase change materials (GT-CPCM) was able to retain up to 45 wt% of SS without leakage. The results of an X-ray diffraction analysis suggested excellent chemical compatibility between the GT and SS, and scanning electron microscopy demonstrated an even distribution of SS within the GT structure. A mechanical characterization of GT-CPCM specimens revealed a maximum compressive strength of 36.66 MPa. Furthermore, the maximum latent heat of the GT-CPCM was 45.01 J/g, its thermal conductivity was 0.435 W/(m·K), and its energy storage density was 563.01 J/g within 25–400 °C. Critically, the GT-CPCM specimens had good cycling reliability after 100 thermal cycles. Thus, the mechanical and thermal properties of this novel CPCM make it ideal for waste heat recovery with the benefit of utilizing GT as a resource.