System-level analysis of the generation and distribution for Pb, Cu, and Ag in the process network of zinc hydrometallurgy: Implications for sustainability

摘要

Heavy metals could serve as both pollutants and resources. To better understand the cleaner production potential of material flow control for simultaneous pollution reduction and resource conservation at source in zinc hydrometallurgy system, the generation and distribution of the Pb, Cu, and Ag in the process network of a typical zinc hydrometallurgy plant were investigated in this study. Four kinds of hazardous wastes with a total dry weight of 942 kg/tZn were identified as the major system outputs for Pb (12.08 kg/tZn), Cu (5.63 kg/tZn), and Ag (70.5 g/tZn). More than 85% of the target substances were accumulated in the leaching and purification subsystem, which determined the final proportion of the substances in the system outputs. The unsatisfactory distribution of the substances in the present process network contributes 0%, 45.9% and 27.5% of final resource wastage or pollution for Pb, Cu, and Ag of the generated wastes, corresponding to 0, 0.53 kg/tZn, and 13 g/tZn, respectively. Presently the Pb wastage or generation of Pb pollution was mainly due to the lack of recovery process. However, the potential to optimize the flow partitioning for Cu is relatively high. In summary, optimization of the process distribution might slightly increase the total recovery rate of the substances, but could significantly reduce the environmental risk of the disposed wastes generated in the zinc hydrometallurgy system. These results will be helpful to improve the understanding of the mechanisms for heavy metal pollution generation and provide further insight in the control of pollution and resource in process industries, such as nonferrous metals industry. (C) 2019 Elsevier Ltd. All rights reserved.