The development of an alternative process for the recovery of lead from sulphide ores

M.Tech. (Minerals Engineering)This report deals with the feasibility study of a novel concept whereby a lead sulphide concentrate and a solid reductant are reacted with a manganese ore at a temperature of approximately lOOO=C. The manganese oxides are reduced to their lower oxides, which, having a higher affinity for sulphur than lead. scavenge the sulphur from the lead sulphide. A manganese sulphide mane is formed. and liquid lead metal is tapped off. The manganese sulphide mane is then leached with sulphuric acid. After a purification step to remove the base metals from solution, the electrolyte proceeds to an electrolytic manganese metal or manganese dioxide facility where the manganese is recovered. The benefits of this process are fourfold: firstly, lead ores may be beneficiated locally; secondly, the separate and often lengthy processes for the recovery of lead and manganese are combined into a simplified process, thereby reducing the capital expense: thirdly, the Leadman process can be applied to any scale of operation: and fourthly, no 502 is produced. Details of the investigation included the following: a literature survey. a laboratory scale study where the operating conditions were narrowed down, a smelting campaign on a rotary kiln, a mineralogical study, a brief leaching study, a leach liquor purification step and a techno-economic assessment. This study has shown the technical and economical feasibility of the Leadman process. The lead and manganese recoveries were both approximately 93%, with good accountability of all the other elements of interest. Depending on the operating conditions, between 80 and 100 per cent of silver, originally in the galena, was recovered with the lead bullion. The purity of the lead metal produced was good with a lead content of approximately 97 per cent, and low levels of contaminants. It was also shown that the manganese matte produced is suitable for use as feed to an existing manganese electrowinning operation. The techno-economic assessment showed a return of R 3 118/t of Pb, compared with R 939/t and R 240/t for the conventional manganese and lead blast processes, respectively