Acid rock drainage prediction and management. A study case of the Uranium Mining and Milling facilities at Pocos de Caldas, MG, Brazil

Acid rock drainage generated as a result of sulfide minerals oxidation is a source of pollution in many mining sites all around the world. This is the case of the Uranium Mining Site at Pocos de Caldas -Brazil. The present study was aimed at studying the geochemical mechanisms involved in the mobilization of radionuclides from the waste rocks that occurs along with the acid drainage. It has been shown that precipitation of Ra and Pb as sulphates was the most important mechanism in the reduction of both radionuclides activity concentration in the acid drainage. It has also been estimated that pyrite oxidation will occur for more than a thousand years. The long time scale involved on the oxidation of the pyritic material implies needs for the adoption of permanent remedial actions. To assess applicable remediation strategies it has been suggested that oxygen and temperature profile determination should be carried out in the dump. (author)