Microwave Roasting Characteristics of Cuprous Chloride Residue from Zinc Hydrometallurgy

Abstract

High-efficiency dechlorination processes are crucial for the clean utilization of CuCl waste residue from zinc hydrometallurgical processes. A new method of oxygen-enriched microwave roasting has been proposed to improve the dechlorination process. The cavity perturbation method was used in this paper to measure the permittivity of a CuCl residue at various temperatures and apparent densities. The results show that temperature had a more significant effect on the loss tangent when it exceeded 400 °C more than that of apparent densities. The degree of dechlorination of CuCl residue exceeded 93% after 90 min of microwave roasting at 450 °C and 150 mL/min oxygen flow, which was 12% higher than that of conventional calcination. The elemental distribution in samples was studied using single-point, linear, and lateral scans at the microscale, and the microstructure and phase changes of the CuCl residue under a microwave field were characterized by XRD and SEM-EDS. This study shows that microwaves can promote the dechlorination reaction by decreasing the activation energy from 52.69 kJ/mol to 42.36 kJ/mol.

Keywords

• microwave roasting
• cuprous chloride
• oxidation
• dechlorination