Abstract
Effect of Microwave Irradiation on Strength Reduction in Rocks
M. Rabiei, P. Samea, S.A. Ghoreishi-Madiseh
Norman B. Keevil Institute of Mining Engineering, The University of British Columbia, Vancouver, British Columbia, Canada
Microwave technology is emerging as a promising tool for improving resource-use efficiency in the mining and mineral processing industry. The mining industry is highly energy-intensive, with excavation of hard rocks accounting for a substantial share of energy consumption. Pre-conditioning using microwave energy leads to the formation of stress concentrations and generates microcracking along mineral grain boundaries, thereby facilitating rock mass fragmentation and the excavation process. During the microwave exposure of microwave, these microcracks coalesce, propagate, and ultimately cause substantial damages. This study applies a coupling of finite element and discrete methods to investigate the electromagnetic-thermal-mechanical effects of microwave treatment on the compression strength reductions of rock samples. The results, validated through experimental benchmark tests, consider heat absorption, temperature distribution, and strength reduction across various power levels and exposure times. Findings indicate that higher microwave power and shorter exposure times lead to more significant rock damage, with notable reductions in compressive strength and enhanced micro-crack formation. These results suggest that microwave technology can be effectively applied in mining and tunneling by increasing the damage and pre-weakening rocks prior to the excavation in an efficient way. This approach can provide both economic and environmental benefits by reducing energy consumption and aligning with sustainable development goals.