Multiphysics study of microwave irradiation effects on rock breakage system

Abstract

The development of a model to describe the Electromagnetic-Thermal-Mechanical (ETM) multiphysics interaction in rocks requires careful consideration of the heating mechanism when microwave irradiation is applied. Since the rock breakage process by microwave energy depends on different microwave operating parameters, such as power level, exposure time, and distance from microwave antenna, a fully coupled numerical modeling approach is necessary to evaluate the corresponding effects, i.e. temperature changes, initiation of mechanical stresses, formation of micro/macro cracks, and disintegration/separation mechanism caused by thermal strains among rock particles from the coupling of ETM multiphysics interaction. To gain a better understanding of the rock breakage system due to microwave irradiation, this paper develops and analyzes numerical simulations of rock-microwave interactions using the finite element method. Several numerical models are conducted, and their results are tested and compared with data obtained from the experiments on basalt samples as part of the validation process. The models and experiments consider different microwave parameters, such as distance from microwave antenna, power level, and exposure time. The models are solved for electrical and magnetic fields, temperature distribution and maximum principal stress. The numerical results suggest that microwave energy has potential application for rock breakage and, therefore, continuous excavation.