Abstract
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.