Determining Acid and Metalliferous Drainage Potential of Waste Rock on a Mine

Abstract

Acid and Metalliferous Drainage (AMD) is recognised as one of the most serious environmental problems in the mining industry. This is because environmental issue of AMD poses serious threat to the future profitability and social licence of the mining operations. AMD occurs when reactive sulphide bearing materials are exposed to oxidising conditions. It has now become imperative for every mining company to test sample of sulphide bearing mineral for their AMD potential before major mining excavations are done. This work determines the AMD potential of fifty (50) waste rock samples from a Mine using Acid Base Accounting (ABA) techniques. Mineralogical studies on the sample indicated that the major sulphide mineral assemblages present in the sample were pyrite, arsenopyrite and chalcopyrite. Paste pH showed that 20% of the samples had undergone weathering and as such AMD generation had already started. 22% of the sample had conductivity levels between 1000 to 10,000 µS/cm.  Paste pH and conductivity can be used as a preliminary AMD predictive tool. Acid Base Accounting showed that 32% of the samples were acid generating, 16% were non-acid forming and 52% were uncertain. The analysis showed that the potential for AMD generation exists for the waste rock samples and the environment, specifically water quality would be affected should AMD occurs without any preventive measures.