440 Waste Management & Research Waste Manage Res 2007: 25: 440–448 Printed in UK – all right reserved

Processing of copper converter slag for metal reclamation. Part I: extraction and recovery of copper and cobalt Clean processing of copper converter slag to reclaim cobalt and copper could be a challenge. An innovative and environ-mentally sound approach for recovering valuable metals from such a slag has been developed in the present study. Curing the slag with strong sulphuric acid, without re-smelting or roast-ing as practiced currently in the industry, render it accessible to leaching, and more than 95 % of cobalt and up to 90 % of copper was extracted together with iron by water leaching, leaving silica behind in a residue. The copper in the leach liq-uor was recovered by cementation with iron and the dissolved iron crystallized as ferrous sulphate monohydrate. The cobalt in the mother-liquor rich in iron was recovered by either cementation or sulphide precipitation. Operation variables in the new process were also investigated and optimized