Abstract
Investigating the generation of local damages in microwave-treated rocks
M. Rabiei, P. Samea, A. Shadi, S.A. Ghoreishi-Madiseh*
Norman B. Keevil Institute of Mining Engineering, The University of British Columbia, Vancouver, British Columbia, Canada
The mining industry has constantly been looking for novel technologies to improve conventional drill and blast methods and to overcome their environmental and safety challenges. Microwave pre-treatment has been reported as a promising technology for reducing the strength of rocks prior to the extraction of precious minerals. Application of microwave energy induces stress concentrations and causes microcracking at mineral boundaries. At high microwave energy levels, microcracks coalesce, propagate, and result in extensive damages. In this study, an indirect coupling between discrete and finite element methods is introduced to study the energy absorption and microwave-induced damage in basalt slabs. The numerical results are qualitatively and quantitatively validated with the experimental benchmark tests in terms of the overall heat absorption, temperature distribution and the exposure time required for the generation of local tensile failures. The effect of different microwave power levels and exposure times on the dilation of sample, the number of generated microcracks, and the change in the strain energy are numerically investigated. It is shown that the extent of damage due to microwave irradiation is more pronounced at a higher power level and lower exposure time. The results suggest that it is possible to generate substantial damage and decrease in the rock strength through microwave treatment prior to the excavation in an efficient way.