Optimizing the design of the dielectric-loaded converging waveguide antenna for enhanced microwave fracturing of biotite diorite

Abstract

Microwave-assisted rock breakage is a promising technique for improving the performance of mechanical excavators in hard rocks in the construction and mining industries. Open-ended dielectric-loaded converging waveguide antennas (DLCWAs) have been identified as the most suitable antennas for fracturing rocks with a low microwave fracturability index. However, optimizing the design of DLCWAs has been challenging due to limitations in simulating the microwave fracturing process of rocks. In this study, a validated method coupling COMSOL Multiphysics and four-dimensional lattice spring model (4D-LSM) is employed to evaluate the performance of DLCWAs with varying opening sizes and transition section lengths. The numerical results reveal a strong correlation between the temperature and fracturing characteristics. An antenna with an opening size of 70 mm × 40 mm and a transition section length of 16 cm is numerically identified as the optimal design for fracturing a fine-grained biotite diorite. To validate the design, the antenna is manufactured and tested for microwave heating and rock breakage. Experimental results show that the optimized antenna supports high-power microwave heating and fracturing and significantly enhances mechanical rock breakage efficiency compared to the original design. This study provides a framework for optimizing antenna designs and addresses the gap in simulating microwave rock fracturing.