Understanding the Water Balance of Potentially Acid Forming Tailings Deposited in a Dry Climate

Authors: Chapman, PJ; Williams, DJ; Rohde, TK; Ennor, SJ Download Paper

DOI https://doi.org/10.36487/ACG_repo/852_45

Cite As:
Chapman, PJ, Williams, DJ, Rohde, TK & Ennor, SJ 2008, 'Understanding the Water Balance of Potentially Acid Forming Tailings Deposited in a Dry Climate', in AB Fourie, M Tibbett, I Weiersbye & P Dye (eds), Mine Closure 2008: Proceedings of the Third International Seminar on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 499-509, https://doi.org/10.36487/ACG_repo/852_45



Abstract:
The conventional deposition of mine tailings as a slurry results in seepage, with the potential to contaminate surface and ground waters, particularly during deposition, and possibly post-closure. In a dry climate, tailings deposition can be cycled to largely evaporate excess water, and on closure the tailings may remain desiccated to the extent that incidental rainfall will not cause seepage to the environment. The purpose of any cover would then be to limit dust, promote some vegetation and improve aesthetics, rather than to shed rainfall runoff, which would result in a poor vegetative cover and erosion. To test this hypothesis, a trial tailings cell at a mine in arid Western Australia has been instrumented with moisture and suction sensors located on towers placed prior to tailings deposition. Tailings were deposited over a number of months in a series of lifts to a maximum height of about 4 m, with desiccation allowed between lifts. The deposit was then left for a period of four months without tailings deposition, during which time the effects of prevailing climatic conditions were monitored. The paper describes the instrumentation and its installation, and the life cycle of tailings deposition and desiccation, and presents the moisture and suction data collected during the deposition and desiccation phases.

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