Removal of arsenic from dusts produced during the pyrometallurgical refining of copper by vacuum carbothermal reduction

Removal of arsenic using the low-temperature vacuum carbothermal reduction method was investigated by taking dusts with high contents of arsenic and copper from furnaces for pyrometallurgical refining of Cu as raw materials. Based on TGA-DSC, differential thermal analysis was applied to the raw materials; by virtue of various methods including XRD, ICP, and SEM: the phases, chemical compositions and morphologies of dusts and evaporation residues were separately analysed; on the basis of thermodynamic analysis, the influences of the evaporating temperature, residual pressure, reductant dosage, and evaporation time on the removal rates of As and other valuable metals were explored. The results show that at an evaporating temperature of 350 °C, the residual pressure of 100 Pa, reductant dosage of 25%, and evaporation time for 50 min, the As removal rate can reach 93.48% while guaranteeing that the other metals are essentially not evaporated. This realises the selective separation of As from the other valuable metals. The evaporation products are higher-purity As2O3, which can be used as a primary As2O3 product. The valuable metals are concentrated in evaporation residues, being conducive to subsequent recovery by leaching with waste acids. •As removal rate can reach 93.48% while realising the effective separation of As from the other valuable metals.•The evaporation products are high-purity As2O3, which can be used as a primary As2O3 product.•The valuable metals are concentrated in evaporation residues, being conducive to subsequent recovery.