Flooding of the underground mine workings of the old Witwatersrand gold/uranium mining areas: acid mine drainage generation and long term options for water quality management

The underground workings in the older parts of the Witwatersrand Gold Fields of South Africa have been abandoned and allowed to flood. Pyrite in the ore and host rock leads to the generation of acid mine drainage in the flooding underground workings as well as in surface residue deposits. The difference in topo-graphic elevation across these goldfields creates a driving hydrostatic head which has caused the discharge of acid mine drainage in the West Rand Gold Field and threatens to cause similar problems in the Central and East Rand. Laboratory simulations and simple models have been used to try to understand the hydraulic and chemical dynamics of the flooding mines with the aim of optimising solutions to this problem in the medium- to long-term.