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

Hydrometallurgical processing of lead-bearing materials generated at zinc p lants 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-si lver-bearing residues. Two approaches have been selected in view of the com plexities of the material. In the first approach, a simple double-decomposi tion technique was selected for treatment of one of the lead-sulphate resid ues by reacting with sodium-sulphide solution after the removal of acid-sol uble metal values to produce a high-quality lead concentrate. In the second approach, the lend-sulphate residue was treated with brine solution and th e resultant filtrate was reacted with sodium-sulphide solution to obtain le ad concentrate or cemented-out lead as lead sponge using aluminium scrap, w hich was then briquetted and melted into lead metal, Alternatively the lead sponge was subjected to roasting to obtain litharge as a value-added produ ct, The processes developed an very simple, easy to implement and cost-effe ctive, eco-friendly with cleaner technology. The recoveries are excellent. The lead concentrate obtained by the proposed processes can be used directl y in the lead circuit and the lead sponge obtained can be melted and cast i nto lead ingot or roasted to produce lead oxide. The quality of lead concen trate, lead metal and lead oxide produced by the processes are also incorpo rated. Based on the results, conceptual flowsheets have been developed to t reat 3-5 tons/day lead-bearing materials. A similar method was applied to o ther lead-zinc-cadmium-silver-bearing materials generated at HZL plants. Th e results are presented along with the flowsheet. (C) 2000 Elsevier Science B.V. All rights reserved.