Experimental investigation into the thermal conductivity of gangue-cemented paste backfill in mine application

Abstract

Gangue-cemented paste backfill is one kind of paste backfill that is composed of cement, fly ash, and gangue, which is widely used in mining operation for controlling the strata movement and guaranteeing the safety of workplace. The knowledge of thermal conductivity of mine backfill is vital for understanding the thermal interaction of backfill with surrounding rock mass and therefore contributing to geothermal energy extraction with backfill technology in deep mines. Thermal conductivity of gangue-cemented paste backfill is investigated through laboratory tests in this article. The influences of mix proportion parameters and water saturation degree on the thermal conductivity of gangue-cemented paste backfill were analyzed. The results showed that thermal conductivity of gangue-cemented paste backfill markedly increased with the water/binder ratio from 0.35 to 0.55, while cement amount ranging from 4% to 12% had nearly no influence on the thermal conductivity. Meanwhile, the linear positive correlation was notable between thermal conductivity and water saturation degree of gangue-cemented paste backfill, which was interpreted from the perspective of component. The series model was found more reliable for predicting thermal conductivity of gangue-cemented paste backfill by importing the thermal conductivity and volume fraction of continuous paste and dispersed gangue separately. This study would provide a new insight into the design of backfill considering the thermal conductivity and lay a foundation for the efficient geothermal energy extraction in deep mines.

Keywords

• Gangue
• Thermal conductivity
• Backfill
• Geothermal energy