Prevention of Acid Rock Drainage (ARD) formation from fine coal and tailings fractions by sulphide removal: The role of bioflotation reagents

Abstract

The South African coal mining industry produces large amounts of sulphide-containing ultrafine waste tailings which pose an Acid Rock Drainage ( ARD) generation risk. A two-stage froth flotation process developed at UCT (Harrison, et al., 2013) aims to further process such wastes: the first-stage produces a desulphurised, saleable coal concentrate and the second-stage produc es a low-volume, highsulphide concentrate and a high-volume benign tailings which is suitable for safe disposal without containment. Two key issues which hamper the implementation of this treatment technique are: (1) the high cost of the oleic acid collector required in the first flotation stage and (2) the toxicity of the xanthate collector used in the second-stage which presents issues with the final product stream handling and use. In this study, microorganisms and bioproducts are investigated as potential bioflotation reagents for use in this two-stage flotation desulphurisation of coal ultrafine waste tailings.

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