Assessment of the quality of Block 4 pit water at Iduapriem Gold Mine, Tarkwa, Ghana

摘要

In AngloGold Ashanti Iduapriem Ltd (AAIL), large quantities of colloidal mine water was found in the Block 2/3 in-pit tailings storage facility. The water contained high concentrations of free cyanide, turbidity, conductivity and selected metals and arsenic. The mine constructed a treatment facility in collaboration with Pollution to Water (P2W) and Israeli Company that efficiently removed free cyanides and turbidity, and decreased the pH. Since the quality never met all the sector specific effluent guidelines, the partially treated water had to be stored in the block 4 pit (approximately 1.83 million cubic meters). This study aimed at assessing the current water quality of the Block 4 pit for an informed decision. Samples of water were taken at surface, middle and bottom layers of the pit for the analyses of metals and arsenic and relevant physiochem-ical variables indicative of pollution. It is evident from the sequence that metal and arsenic concentration of the surface water layer is a reflection of the entire water column. It was recommended that media filters and reverse osmosis be installed to handle the rest of the parameters in the block 4 pit water and any other waters on the mine for it to meet the EPA sector effluent discharge limits.