Influence of microwave heating on the processing and dissolution behaviour of low-grade complex sulphide ores

摘要

This study provides an understanding of the way in which microwave treatment affects the processing and recovery of complex sulphide ore. The influence of microwave irradiation on the heating characteristics, breakage response, mineralogy, and the mechanisms of dissolution in sulphuric acid and hydrochloric acid was investigated. It was observed that both ore mineralogy and microwave heating had dual effect on each other. Microwave heating at increased power and time had a positive effect on size reduction, due to internal stresses arising from the complexity in the mineralogy which induced cracks within the matrices of the ore. Microwave irradiation did not cause any significant mineral phase change, but altered the peak intensities of sphalerite and pyrite. Dissolution potentials were shifted to more negative values after microwave treatment, while dissolution currents, dissolution current densities, and dissolution rates were also increased. Dissolutions were higher in hydrochloric acid medium. An increase in dissolution rate after microwave treatment was also observed in sulphuric acid media. The increase in dissolution of the microwaved treated samples was attributed to an increase in electrochemical sites resulting from an increase in the number of cracks, and increased pyrite phases which promoted galvanic interaction within the system.