Gauteng Province, South Africa will have a shortfall of 400 ML/d of fresh water by 2014. This shortfall can be made up either by purchasing additional expensive water from the Lesotho Highlands Scheme or by; treating acid mine water. The CSIR ABC (alkalibarium-carbonate) Process is a most cost-effective process as the sludge produced is processed back to the process raw materials and valuable by-products, such as sulphur. Coal is the main material used in processing the sludge.
The chemical processing of barium sulphide into barium carbonate and elemental sulphur has been demonstrated on a pilot scale in batch mode. The barium sulphide was reacted with carbon dioxide at ambient temperature and atmospheric pressure to produce BaCO3 and H2S. The H2S generated, was contacted and oxidized with ferric iron solution to form elemental sulphur. Over 80% of the barium reacted during the carbonation process while all the sulphide was converted to H2S. The reaction rate of barium carbonation was found to increase with increase in CO2 flowrate. The pilot plant has produced BaCO3 and sulphur of high quality compared with commercial products in terms of reactivity and purity, respectively. The BaCO3 produced was used in acid mine drainage treatment and lowered sulphate concentration from around 2500 mg/L to 415 mg/L. The outcome of this project will assist in solving the problem of economic acid mine drainage treatment, using regenerated barium carbonate. Moreover, the project also aims to enable the generation of income through recovery of valuable by-products.