Hydrometallurgical processing of lead-bearing materials for the recovery of lead and silver as lead concentrate and lead metal

摘要

Hydrometallurgical processing of lead-bearing materials generated at zinc plants is described. Two types of lead sulphate generated at the smelters of Hindustan Zinc (HZL) have been used, in addition to other types of lead-silver-bearing residues. Two approaches have been selected in view of the complexities of the material. In the first approach, a simple double-decomposition technique was selected for treatment of one of the lead-sulphate residues by reacting with sodium-sulphide solution after the removal of acid-soluble metal values to produce a high-quality lead concentrate. In the second approach, the lead-sulphate residue was treated with brine solution and the resultant filtrate was reacted with sodium-sulphide solution to obtain lead concentrate or cemented-out lead as lead sponge using aluminium scrap, which was then briquetted and melted into lead metal. Alternatively, the lead sponge was subjected to roasting to obtain litharge as a value-added product. The processes developed are very simple, easy to implement and cost-effective, eco-friendly with cleaner technology. The recoveries are excellent. The lead concentrate obtained by the proposed processes can be used directly in the lead circuit and the lead sponge obtained can be melted and cast into lead ingot or roasted to produce lead oxide. The quality of lead concentrate, lead metal and lead oxide produced by the processes are also incorporated. Based on the results, conceptual flowsheets have been developed to treat 3-5 tons/day lead-bearing materials. A similar method was applied to other lead-zinc-cadmium-silver-bearing materials generated at HZL plants. The results are presented along with the flowsheet.