Zinc and lead recovery from jarosite residues produced in zinc hydrometallurgy by vacuum reduction and distillation

Abstract

Jarosite residues in zinc hydrometallurgy are considered as hazardous waste as they contain heavy metals such as Zn and Pb. A novel vacuum reduction and distillation process has been put forward to recover Zn and Pb from jarosite residues. Four main factors including the amount of coke powder, amount of lime powder, heating temperature, and holding time which have an influence on volatilization of Zn and Pb were studied in this paper by the statistical software JMP. The results show that heating temperature is the key factor among the four contributing factors. By examination of the relationship between the four factors and the volatilization of Zn and Pb, it is indicated that a heating temperature of 1000°C, holding time of 90 min, and addition of 29.6% coke powder and 13% lime powder to the residues led to optimum ratios of 99.4% of both Zn and Pb volatilization. The results show that this process is an effective method in dealing with zinc, lead, and iron in jarosite residues and it is an environment-friendly process.

Keywords

• jarosite residues
• lead
• reduction
• volatilization
• zinc