Comparison study of three universal methods for the recovery and purification of valuable heavy metals from electroplating sludge

Abstract

The large amount of heavy metals from waste electroplating sludge has great recovery and treatment value, which is of great significance for environmental protection, resource recycling and sustainable development. In actual process, metals were relatively easy to be extracted from sludge, but the separation process was more complex. In this study, three universal methods for extracting low-grade and complex heavy metals from electroplating sludge (actual solid waste sample from Zhejiang Province, China) in terms of Selective ammonia treatment process (SAP), efficient acid treatment process (EAP) and roasting-acid treatment process (RAP) were investigated. In comparison, EAP was more advanced in extracting heavy metals from actual samples than SAP and RAP. It was noticed, by optimizing the separation and purification process, when the acid concentration was 5 % and the liquid–solid ratio was 10:1 with the assistance of effective extractants of Lix984N and P507, the purity and recovery rates for both copper and zinc products could reach to over 90 %, meanwhile, more than 80 % recovery rates of nickel products could be obtained. And compared with some existing related studies, the research process has the advantages of simpler operation mode and better separation effect, which offers the valuable insights into efficient separation and recovery of heavy metal resources from electroplating sludge. The methodology employed in this work can be easily applied to other solid/hazardous waste extraction processes.