Sustainable reduction of heavy metal pollution in zinc electrowinning: Insights from a cleaner production perspective

Abstract

Cleaner production (CP) can mitigate environmental harm caused by human activities and increase efficiency through whole-process control, promoting sustainable industrial development and reducing heavy metal pollutants. Heavy metal pollutants from zinc electrowinning have become pressing global concern. This review aims to introduce advanced methods and innovative technologies from 212 sources to enhance zinc electrowinning sustainability. Herein, the focus is on investigations of how to achieve sustainable emission reduction of heavy metal pollution in cathode wastewater and anode slime through CP perspectives and philosophy, including key processes, pollution causes, CP solutions, and implementation effects. Taking the heavy metal pollution at the anode and cathode as the starting point of technical methods, which methodology and details of each typical method were discussed. There were 4 promising technologies were found and highlighted: in situ brushing, efficient needle spray cleaning, pre-coated anode, and precise anode slime removal. The implementation of a complete CP technology set reduced plate cleaning wastewater by more than 80%, and plate anode slime by more than 85%. Additionally, by comparing reported outcomes in studies, big gaps in technology transformation from the existing research to the actual industrial application were found, and practical recommendations for further improving CP aspects of zinc electrowinning were provided. This review should prompt researchers to actively consider how to optimally apply the CP concept to the sustainable development of industry and society.