New Vaal Colliery (NVC) is an opencast mine in the northern Free State, located within a meander of the Vaal river and underlain by the Transvaal Supergroup dolomitic aquifer. Dewatering of the pits results in high-sulphate water that needs to be stored in the Maccauvlei dam, the main unlined pollution control dam. In 2011 the mine was issued a water use license containing challenging conditions, one of which was the requirement for all water pollution dams on site to be lined.
Arsenic is a common contaminant typically found in effluent from gold mine operations and copper smelters throughout the world. The geochemical behaviour of arsenic in contact with dolomite underlying an arsenic containing waste rock pile was investigated. The interaction between the arsenic and the dolomite is an important control in the subsequent transport of the arsenic in the dolomitic aquifer. Rocks with varying dolomite content were tested to investigate the interaction between the arsenic and dolomite.
Numerical Modelling Of a Coal Mine to Improve the Understanding of Mine Water Decant: A 1000-Piece Puzzle
A coal mine in South Africa had reached decant levels after mine flooding, where suspected mine water was discharging on the ground surface. Initial investigations had indicted a low-risk of decant, but when ash-backfilling was performed in the defunct underground mine, decant occurred. Ash-backfilling was immediately suspended as it was thought to have over-pressurised the system and caused decant. Contrariwise, a number of years later decant was still occurring even though ash-backfilling had been terminated.