SUSTAINABLE FULL-SCALE REHABILITATION OF POLLUTED MINE TAILINGS AND ACID MINE DRAINAGE (AMD)

For more than 150 years of mining in South Africa, nature has had to deal an accumulation of polluted substances. Destruction of rock by explosives exposes new surface areas with an abundance of water-soluble elements. The common remediation technique used for acid mine water is treatment with lime or with caustic soda. These tech-niques are not effective enough to keep the environment free of residues and don’t provide a sustainable treatment of acid mine drainage (AMD). The long- term environmental result of treatment with caustic soda is saline soil and could in addition, lead to irreversible soil sterility. A remediation technique for cleaning highly polluted AMD water should raise the pH and immobilise the heavy metals, keeping them out of the system permanently. With an organic medium – an organic material, a mixture of a specific Casuarina needle and a specific, pine bark with 2 other semi decomposed plants- it was proven that even in pH ranges of below pH 3.5, high concentrations of Mn and Fe may still be removed. Only, after immobilising and binding heavy metals and treating up to 10,000 m AMD per day, for at least two years, the organic medium has to be replaced. The quality of the treated AMD is confirm to the minimum guidelines for agricultural purposes and can be used for irrigation. The used material can be deposited on certified hazardous waste dumps, or could be recovered and recycled fo