JOHANNESBURG (miningweekly.com) – Government’s acknowledgment of the severity of acid mine drainage (AMD) in the Witwatersrand, Gauteng, and the subsequent priority given to taking steps to alleviate the problem are of “significant importance”, states Federation for a Sustainable Environment (FSE) CEO Mariette Liefferink.
After years of numerous mines having decanted, or verged on the precipice of decanting acid mine water, the Department of Water and Sanitation (DWS) has taken strategic steps with the allocation of funds and plans to tackle the issue of acid mine water poisoning water courses throughout South Africa.
Acid mine water is commonly referred to as AMD. AMD is generated when sulphide-bearing minerals, often in the form of pyrite (which is iron sulphide found in reefs mined for gold), are exposed to oxygen and water. This process, termed pyrite oxidation, is characterised by the generation of sulphuric acid and dissolved iron.
The build-up of AMD has been taking place over several decades, but has seen its worst impact at abandoned mines, which no longer operate dewatering pumps and AMD treatment plants. Thus, nature has been allowed to set its course, with a high risk of poisoning above- and below-ground water resources.
AMD is generally characterised by a number of factors, including a low pH level (high acidity), a high salt content (mostly made up of sulphates) and high levels of metals – particularly iron – giving AMD a characteristic red-orange colour. In addition, where uranium is present, radiological risks may also be present in conjunction with the threats of AMD. Water and Sanitation Minister Nomvula Mokonyane announced in May that a yearly allocation of R600-million will be committed to directly address the AMD issue.
The budget will come from the National Treasury. The announcement was made at the South West Vertical Shaft, in the Central basin, in Germiston, where the DWS hosted industry experts, together with the implementing agent, the Trans-Caledon Tunnel Authority.
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