Problematic pit: closure liability to operational opportunity

Authors: Latham, CL; Lazo-Skold, C

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DOI https://doi.org/10.36487/ACG_rep/1915_98_Latham

Cite As:
Latham, CL & Lazo-Skold, C 2019, 'Problematic pit: closure liability to operational opportunity', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1241-1254, https://doi.org/10.36487/ACG_rep/1915_98_Latham

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Abstract:
This paper presents a case study of an innovative solution to a problematic mined-out pit in the Pilbara region of Western Australia. The pit presented significant closure challenges, being deep, below water table and with approximately 17% of potentially acid forming (PAF) lithology on the final pit shell. Numerous closure strategy options have been under consideration; however, a new strategy of backfilling the pit with process tailings has been identified. Modelling predicts that the tailings will cover a large proportion of the PAF lithology leading to improved water quality conditions and will also fill the pit to a level that prevents the formation of a permanent pit lake. Furthermore, the initiative will negate the need for construction of further ex-pit tailings capacity and prevent the associated environmental impacts. Significant cost savings in tailings facility construction, tailings deposition and closure implementation are anticipated. Regulatory approval of the in-pit tailings facility is required, and consultation has commenced.

Keywords: pit lake, tailings, potentially acid forming waste, acid mine drainage, closure

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