Mechanism and kinetics study on waste acid leaching from copper smelting dust

Copper smelters generate large amounts of copper smelting dust (CSD) that has a high recycling value because it contains about 20% copper. Waste acid can be used to leach CSD. Here, the effects of different temperatures, times and liquid-solid ratios on copper, iron and arsenic leaching rates were investigated. The optimal conditions were determined to be a temperature of 95 degrees C, leaching time of 3 h, and liquid-solid ratio of 7:1. Under these condition, the leaching rate of copper reached 96.37%, and the copper ion concentration was 32.71 g/L. The leaching kinetics date revealed that the leaching of copper and iron was controlled by two different reaction models. The leaching of copper conformed to the Johnson-Mehl-Avrami (JMA) model and was diffusion controlled, and the reaction was rapid in the first 60 min. In contrast, leaching of iron was controlled by a chemical reaction. Copper and iron activation energies were 2.579 and 62.791 kJ/mol, respectively. These results show that CSD waste acid is can be used to dispose of arsenic-containing hazardous waste in a green, sustainable, and ecologically method.