Effects of particle size and morphology on microwave cracking characteristics and cracking mechanism of three Fe-containing ores

Abstract

Microwave irradiation is a potential technology for use in rock fracturing. It is of great significance for the application of microwave technology in metal mines to understand the microwave cracking characteristics of ores and the mechanism of microwave action of ores. Taking Hongtoushan copper ore, Sishanling iron ore, and Dandong gold ore as research objects, the microwave cracking characteristics of ores with different morphologies (bulk/particle samples) and particle sizes were investigated. The microwave action mechanism of ores was revealed based on dielectric properties and arc characteristics. The results show that the change in morphology of the ore affects the microwave cracking characteristics thereof. The failure of iron ore and gold ore is characterized by the generation of cracks and the crack direction is related to the ore morphology. The bulk copper ore is not damaged after microwave irradiation, but the damage to particles of copper ore is characterized by scorching or scorching and melting accompanied by cracks. The more power applied, the larger the particles, and the stronger the arcing. Compared with the type and morphology of ore, particle size has little effect on dielectric properties. The microwave action mechanism of bulk copper ore (smooth surface) is a reflection effect and that of bulk copper ore (rough surface) is a discharge effect. The microwave mechanism of action on particulate copper ore is the combined action of discharge and heating effects, which leads to fracture. The microwave mechanism of action on iron ore and gold ore is mainly one of heating. The research results provide guidance for the development of microwave ore-cracking equipment and the selection of the optimal heating sequence.