International Journal of Mineral Processing, Vol.135, 40-51, 2015
Microwave propagation and absorption and its thermo-mechanical consequences in heterogeneous rocks
A numerical analysis in a two-component model rock is presented including the propagation and absorption of a microwave beam as well as the microwave-induced temperature and stress distributions in a consistent way. The analyses are two-dimensional and consider absorbing inclusions (discs) in a non-absorbing matrix representing the model of a heterogeneous rock. The microwave analysis (finite difference time domain - FDTD) is performed with values of the dielectric permittivity typical for hard rocks. Reflections at the discs/matrix interfaces and absorption in the discs lead to diffuse scattering with up to 20% changes of the intensity in the main beam compared to a homogeneous model rock. The subsequent thermo-mechanical finite element (FE) analysis indicates that the stresses become large enough to initiate damage. The results are supported by preliminary experiments on hard rock performed at 2.45 GHz. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
Keywords:Microwave heating;Rock damage;Microwave analysis;Thermally induced stresses;Microwave irradiation experiments