Microwave-assisted damage and fracturing of hard rocks and its implications for effective mineral resources recovery

Abstract

Microwave radiation can be used to pre-damage hard rock to reduce the cost of drilling and excavation typically required in tunneling, mining, and deep Earth energy recovery. A 3D damage-based, electromagnetic-thermo-mechanical coupled model to simulate damage and fracturing of rock under microwave radiation is proposed in this manuscript. The model is first validated against experimental test and then used to simulate the damage and fracturing of rock under microwave radiation at various microwave power levels and radiation times. The simulations show that the distribution of temperature in the rock sample is extremely non-uniform, resulting in high thermal gradients that can damage and/or fracture the rock sample. Higher power levels and longer durations impart more damage. The simulations also show, under the same microwave radiation conditions, that the resultant sample temperature, and therefore damage, is higher in samples with high ratios of compressive to tensile strength. A good agreement between the modeling and experimental results suggests that the model can be used to assist in the management and optimization of mineral mining, oil and gas recovery, and deep Earth energy recovery.