Conceptualising a regionally integrated approach for the valorisation of coal mining-related waste: A case study in the Mpumalanga Province, South Africa

Coal is currently an important energy source for the South African economy and is likely to remain so in the medium term. Coal extraction, processing and combustion, however, produce industrial wastes, which can pollute soils, water resources and air and also occupy large tracts of land, sterilising these for a variety of uses. Current waste management approaches, including co-disposal, lining tailings dams and covering waste facilities with soil and vegetation, require monitoring and maintenance over hundreds of years, increasing the risk of environmental failure in the future. An integrated approach aimed at valorising whole waste bodies and simultaneously remediating the surrounding environment is proposed here. This approach considers solid and slurry coal mine wastes, fly ash, acid mine drainage, and gypsum. Different repurposing options are identified for each waste stream, these are screened, and an integrated solution to mine waste repurposing for the Mpumalanga coal mining region is recommended. Among the recommendations that form part of the integrated approach are that benign coal mine waste be used for a combination of fabricated soil production and backfill and that iron be recovered from acid mine drainage prior to neutralisation.