Flotation in acid mine drainage control: Beneficiation of concentrate

This paper is focused on recovering residual sulfide minerals by flotation from the tailing of the Pyhasalmi Cu-Zn mine in Finland. The tailing contains 4-8% sulfide sulfur and according to the static test it is strongly acid producing, having a low ratio of neutralization potential to acid production potential (NP/AP < 1). The NP/AP ratio could be markedly improved (> 1) by flotation treatment of the tailing. Fine pyrite caused sulfide losses in the flotation while incomplete liberation had only a minor effect on the acid production potential. The cleaner concentrate obtained during the flotation of the tailing contained 33% sulfur, 1% zinc, 0.7% copper, 2.8 g/t gold, and 40 g/t silver. Potential process options are available today for partial beneficiation of the concentrate but further development work is needed for recovering all the valuable elements and eliminating the waste pile. (C) 1997 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.