Recovery of lead, silver and manganese from anode mud generated at zinc smelter Debari (Udaipur)

Abstract

Anode mud is a waste generated during electrolysis of Zinc sulphate solution using Lead as anode and Aluminum as cathode. Anode mud deposited on lead anode is rich in Pb (10–15%), Ag (0.03–0.05%) and Mn (35–40%). Approximate quantity generation per annum is 1800 DMT at Zinc smelter Debari. As per present practice, part of anode mud is recycling back to the system and remaining major part is disposed off in dumping yard. A scheme is developed by the quality team of ZSD to recover all the valuable metals like Pb, Ag and Manganese from anode mud. Anode mud is treated with Sulphur dioxide gas. Availability of SO2 is from our roaster plant where ZnS is roasted in a fluo-solid roaster. Recoveries of the entire valuable metals are excellent i.e. more than 98%. No waste is being generated. Pb-Ag residue (Pb: 55–60% and Ag: 0.3–0.4%) is being dispatched to Ausmelt plant, another unit of HZL situated at CLZS, Chittorgarh (Rajasthan). Manganese sulphate solution (Mn content 100–120 gpl) is sold to the market for better realization. The anode mud generated at Zinc smelter Debari is covered under hazardous waste category. Part of this mud is recycled back to the system for build up of manganese in the system and extra quantity is stored in secure land fill. There is a serious problem to store it more than certain period as per the pollution dept norms.