Environmental impact of typical zinc smelting that implements solid waste collaborative utilization in China

Purpose: Large stocks of many kinds of zinc smelting solid waste have been generated; moreover, the disposal process consumes high amounts of energy and takes low output rate of metal resources, which seriously endangers regional ecological environment and human health. The purpose of this study is to compare the environmental impact of the production process of zinc in the “traditional smelting mode” and the “solid waste synergism mode”; to further investigate the efficiency of material utilization, resource recovery, and carbon reduction in the two modes; and to provide expectations and suggestions for reducing environmental risks. Methods: This study focuses on a typical zinc smelting enterprise in China, with the help of SimaPro 9.0 software, to compare and analyze the differences in direct, indirect, and overall environmental impacts between the “traditional mode” and the “synergism mode,” with a focus on the production and waste disposal processes. At the same time, the potential environmental burdens and carbon emission levels that could be reduced by solid waste co-processing are further investigated. Results and discussion: The results show that although the environmental burden of “the acid production from flue gas” is slightly higher in the synergism mode than the traditional mode, the environmental burden caused by all other processes is reduced by more than 20% and the energy consumption is reduced by 20.6–21.4% with the synergism mode. For the waste residue disposal process, the recovery rate of valuable components, such as Zn, Cd, and In, increased approximately 30% compared with the traditional mode, and the total environmental burden is reduced nearly onefold. In addition, the “concentrate + slag” smelting method has reduced zinc concentrate consumption per unit of zinc product by 26.7% and cut carbon emissions by 57.3%. Conclusions: Solid waste co-processing can effectively reduce the stockpiling of waste residues and perform secondary recovery of metal resources. Enhancing the solid waste collaborative utilization level can greatly reduce environmental risks and realize resource recycling for nonferrous industry.