Coupled electromagnetic heat transfer model for cemented tailings backfill cured by microwave energy

Cemented tailings backfill (CTB) is a composite material containing binder, tailings and water, and it is commonly made available for filling mine-out areas and managing waste tailings. When backfilled, the CTB strength and its gain rate should be guaranteed for safe and efficient mining. It is acknowledged that increasing the CTB temperature is beneficial to its strength development. For this reason, microwave heating is introduced and applied to raise the CTB temperature quickly and thus accelerate its strength gain. To date, no numerical research has been conducted to investigate the electromagnetic and thermal properties of microwave cured CTB. Therefore, the present study proposes a coupled electromagnetic heat transfer model for the CTB heated by microwave energy. This proposed model considers the conversion of energy (electrical to electromagnetic and then to thermal), courses of heat conduction and convection, and relevant temperature variation. Two groups of experimental data are used to verify the prediction ability of the model simulation, and this model can accurately describe the thermal properties of the microwave heated CTB. Based on the validated model, the effects of input power, frequency and sample dimension on the distribution of heat and electromagnetic field are discussed. This study can be a contribution to the optimization of microwave parameters and sample dimension, for higher temperature development, less energy consumption and more uniform heating, in future laboratory experiments and field applications.