Acid Mine Drainage Potential of the Coral Snake Waste Dump, Anglogold Ashanti, Obuasi Mine

Abstract

This paper assessed the Acid Mine Drainage (AMD) potential of the Coral Snake Waste Dump located close to the Enkansu and Kaw streams in Obuasi. Ten water and fifty rock samples were analysed for physico-chemical parameters. Acid Base Accounting (ABA) determinations using static methods were employed to ascertain AMD potential of the dump. The modified ABA and the High Temperature Combustion methods were used to determine the Neutralisation Potential (NP) and the Maximum Potential Acidity (MPA) of the various rocks at the dump. The Net Neutralisation Potential (NNP) and Neutralisation Potential Ratio (NPR) of the rocks were calculated from the values of the NP and MPA. The pH of the streams ranges between 7.09 and 7.81. As and Pb concentrations in the streams were above WHO limits for drinking water. The major constituents of the waste dump; phyllites and greywacke constituting about 75.0 % of rocks are not acid generating. The schist and oxide minerals have negative NNP and MPA implying that they are acid generating. However, quartzite analysis indicates they lie in the uncertainty zone. The results show that the Coral Snake Waste dump is not acid generating, although As and Pb levels in streams are issues of major concern.