Numerical simulation of microwave-infrared sorting of selected sulfide ores

Microwave-infrared (MW-IR) ore sorting has been demonstrated to effectively separate ore from waste, enabling the rejection of low-grade material from ore streams or the enrichment of valuable ore from waste. Consequently, this technology presents substantial research value and market potential. It should be emphasized that the intrinsic heterogeneity of ores is a critical factor that must be considered in sorting. In this study, a heterogeneous ore geometric model was developed to achieve bidirectional coupling between the electromagnetic field and solid heat transfer. The microwave heating behavior was systematically analyzed under varying mineral contents, mineral assemblages, and ore orientations, and the implications for MW-IR ore sorting were discussed. The results indicate that the temperature field distribution is highly dependent on the electric-field distribution. Increasing the content of high-loss minerals intensifies the “corner effect” during microwave heating. Furthermore, the dielectric properties of microwave-absorbing minerals significantly modulate the temperature field distribution of mineral assemblages; specifically, the weak dielectric response of sphalerite leads to anomalous heating behavior in the Quartz+Sphalerite assemblages. Ore orientations appear to have little influence on the spatial distribution of thermal hotspots. Moreover, no clear correlation was observed between ore temperature or non-uniformity metrics and mineral content. Notably, even with identical mineral types and contents, changes in ore orientation can significantly affect temperature levels and non-uniformity. Accordingly, heterogeneous particle-packing models that more closely represent real ore morphologies are recommended for further investigation of additional factors governing microwave heating behavior. • A heterogeneous ore model for microwave heating was developed, and temperature characteristics and non-uniformity were quantitatively evaluated. • Increasing the content of high dielectric-loss minerals leads to a more pronounced “corner effect” during microwave heating. • The weak dielectric response of sphalerite causes unusual thermal behavior in Qtz+Sp composite ores. • Microwave heating behavior of ores is governed by multiple interacting factors.