Clean utilization of CuCl residue by microwave roasting under the atmosphere of steam and oxygen

•A new method of dechlorination by microwave roasting was brought up.•The conventional and microwave experiments were carried out.•The phases variation of CuCl residue in microwave field was characterized.

The clean utilization of the CuCl residue containing chloride produced from zinc hydrometallurgy residue is very important for the recycling of valuable metals. In order to strengthen the process of dechlorination, a new method of microwave roasting under the atmosphere of steam and oxygen was put forward. It was demonstrated that the dechlorination rate of CuCl residue by microwave roasting was higher than that of conventional roasting by tubular resistance furnace under the same conditions (temperature, holding time and atmosphere). After roasting at a temperature of 450 °C for 80 min under a gas flow rate of 150 mL/min in microwave filed, the dechlorination rate of CuCl residue was as high as 97%, increasing 18% compared to that of conventional roasting using tubular resistance furnace. The chatacterization of phases variation of CuCl residue in microwave field by means of XRD, SEM-EDS and Raman spectroscopy indicated that the process of dechlorination by microwave roasting under the atmosphere of steam and oxygen was much more efficient than conventional roasting.

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