A sustainable approach for recovering copper and zinc from copper smelting flue dust: Paving the path for waste reduction

Abstract

The recovery of metals without generating secondary waste is a critical focus in the management of hazardous copper smelting dust. To tackle the challenges associated with arsenic-containing solid waste and waste acid generated by traditional recycling processes, we propose a two-stage roasting process that prioritizes low-temperature roasting for arsenic removal, followed by high-temperature roasting for desulfurization of sulfates. This work focuses on the high-temperature desulfurization behavior of residue after arsenic removal. The changes in composition during roasting were analyzed using TG-DSC, XRD, and SEM. The results revealed that the reaction temperature and the addition of bituminite are pivotal in the desulfurization process. The optimal roasting conditions were obtained to be a reaction temperature of 700 °C and a roasting duration of 3 h. Subsequently, approximately 98.77% of copper and 97.17% of zinc could be leached under conditions of a leaching temperature of 80 °C, a reaction time of 4 h, a sulfuric acid dosage of 3 times the theoretical amount, and a liquid-to-solid ratio of 10:1. This process mitigates the generation and accumulation of arsenic-containing waste acid during copper electrodeposition in the traditional hydrometallurgical process of copper smelting flue dust. It lays the foundation for clean and efficient recovery and also provides insights for recycling other copper-containing wastes.