Evaluation of acid mine drainage potential of waste rock at Iduapriem gold mine

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An ARD (AMD) evaluation study was carried out on waste rock material mined from four pits and an existing waste dump at Iduapriem Gold Mine, located at Tarkwa in the Western Region of Ghana. The waste rock materials were subjected to various analysis namely, x-ray diffractometry, microscopic examination, chemical and evaluation Acid Base Accounting (ABA). The study revealed that material Pits I & 2, showed presence of pyrite, a potential source for ARD generation. Material from Pits 3 & 4, did not show any presence of pyrites, rather acid consuming material, such as calcites, feldspar and amphibole. The acid generation potential of material from Pit I was confirmed from leachate emanating from Block I North waste dump. Leachate samples showed levels of low pH and increasing concentration of metal ions in solution and other parameters. Sulphate ions also increased significantly as a result of the products generated in the reaction process. The most prominent indicators were manganese ion (Mn2+), sulphate ion (S042-) and conductivity. The information gathered was then used in proposing the suitable waste dump design which could control the generation of acid. The first suggestion was the inter-layering of the waste with acid-generating and acid-consuming waste material from Pits I &2 and Pits 3&4 respectively. Also suggested was the review of the economic viability of re-handling (digging out) part of the reactive waste and then capping it with acid consuming waste material. This could be compared with the cost of treating leachate from the waste dump, which could take many years.
A thesis submitted to the Board of Postgraduate Studies, Kwame Nkrumah University of Science and Technology in partial fulfilment of the requirements for the award of Master of Science degree in Environmental Resources Management, 2001