Search

• Single-mode microwave heating of rocks is evaluated both numerically and experimentally. • Fully-coupled modeling of electromagnetic and thermal phenomena is presented. • Microwave-induced heat within sample is simulated and verified against calorimetric measurements. • Model is quantitively and qualitatively validated with experimental results. • Effects of post-treatment sample handling are studied. Enhancement of mineral resources exploitation efficiency is one of the main targets identified by the mining industry. However, rock fragmentation, including excavation and comminution, is among the most energy-intensive activities imposing a substantial economic burden on the industry. The microwave pre-treatment technique has offered promising solutions in pre-weakening rocks and ores. This paper investigates the fully coupled electromagnetic and thermal effects of microwave treatment of rocks. A numerical simulation tool based on the finite element method is developed to simulate the microwave-treatment process occurring within the microwave cavity. Temperature-dependent dielectric properties are employed to ensure a bi-directional coupling between the interfaces. The simulation results are quantitatively and qualitatively compared with experimental investigations and validated with less than 3% numerical error. [ABSTRACT FROM AUTHOR]

• Novel method developed to evaluate the energy effectiveness of microwave-assisted fragmentation. • Two new parameters are introduced to assess the heating and weakening impacts of microwave irradiation on rocks/ores. • Single-mode and multi-mode microwave cavities are studied and compared. • Effects of sample size with respect to wavelength and its distance from microwave waveguide are investigated. • Microwave weakening impact is significantly enhanced by improving cavity configurations. Enhancing the energy-effectiveness of microwave-assisted fragmentation is one of the overlooked areas in the published literature. A novel calorimetric technique is proposed to quantify the effect of inductive heating within a microwave cavity on subsequent rock/ore fragmentation. Two new parameters are introduced to identify, differentiate, and quantifiably evaluate the effects of microwave-induced energy and thermally induced fracturing on mechanical strength degradation. Additionally, the influences of sample geometry and position and orientation with respect to the microwave waveguide are experimentally investigated to determine optimum conditions for microwave treatment. Comparisons with published literature show that establishing optimum electromagnetic heating conditions significantly improves microwave-induced weakening. Microwave-assisted degradation has significant potential application to in-situ mining, tunnelling, rock breakage, and comminution. [ABSTRACT FROM AUTHOR]