Numerical and experimental analysis of rock-breaking characteristics of basalt under microwave irradiation

The Microwave-Direct Rock Destruction (MDRD) method is employed to utilize microwave energy for inducing phase transitions in rock, thereby enabling rock removal without physical contact between mechanical tools and the target substrate. This non-contact rock fragmentation approach holds promise for mitigating mechanical tool wear issues associated with traditional rock-breaking methods. To investigate the effects of power input modes on the rock-breaking performance of MDRD, a systematic analysis was conducted to assess the interaction effects of key parameters (Power conversion point, initial microwave power and microwave power width) on the rock-breaking characteristics through single-factor and central composite experiments, followed by the optimization of these parameters. Additionally, a multi-physics numerical model was developed to analyze the energy evolution and pore-forming processes during MDRD. The results indicated that an increasing power conversion point can enhance the rock-breaking efficacy, whereas excessively high or low initial microwave power or microwave power width negatively impact the melting hole formation and MDRD effectiveness. In the MDRD process, a gradual transition of the microstructure within the melt hole to a glassy state is observed, while microstructural damage in the outer region continues to escalate. Furthermore, the microwave polarization mode and the temperature-dependent electrical characteristics of the rock were found to dictate the distribution of the electric field and microwave energy within the rock, thereby influencing both temperature distribution and the morphological evolution of the melt hole shape. This study contributes to the understanding of the interaction between microwave transmission and rock, providing strategic insights for the optimization of the MDRD process.