Microwave-Assisted Mineral Processing: Mechanisms, Comminution Performance, Scale-Up, and Commercialization Challenges

Microwave pretreatment can selectively heat mineral phases and generate thermal stresses that weaken ores before comminution, with possible benefits for subsequent mineral processing. This review examines microwave–mineral interactions, applicator configurations, ore characteristics, comminution and downstream processing responses, and the progression from bench-scale testing to pilot and field-scale implementation. The quantitative synthesis includes 24 bench-scale and 6 pilot-scale studies reporting reductions in comminution energy. The reported conditions vary widely and cannot be directly compared because microwave frequency, applicator geometry, particle-size basis, impedance matching, and definitions of microwave energy input differ among studies. Most bench-scale studies used specific microwave energy inputs above 100 kWh/t, while only three studies in the compiled dataset achieved a favorable microwave-to-comminution energy balance at inputs below 2 kWh/t. In the pilot-scale dataset, selected continuous systems operated at 0.7–3.2 kWh/t and achieved measurable reductions in comminution energy, although the magnitude of the response remained ore-specific. Industrial evidence is less mature and currently consists largely of field demonstrations, prototype systems, and company-reported trials rather than sustained peer-reviewed commercial operating data. Across scales, performance depends strongly on mineralogy, dielectric contrast, particle and grain size, power density, residence time, coupling efficiency, and absorbed energy. Wider implementation therefore requires standardized energy reporting, improved applicator design and process control, representative pilot-scale validation, and rigorous techno-economic assessment.