Repurposing of the Genex Kidston mine site in Queensland, Australia

Authors: Williams, DJ; McGhie, A; Short, T Download Paper Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2215_57

Cite As:
Williams, DJ, McGhie, A & Short, T 2022, 'Repurposing of the Genex Kidston mine site in Queensland, Australia', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 789-802, https://doi.org/10.36487/ACG_repo/2215_57



Abstract:
The Genex Kidston mine site is among the best examples in Australia of repurposing post-closure. The paper presents the rehabilitation history of the Kidston mine site as it approached closure in 2001, and the performance of the rehabilitation over the last 20 to 25 years. The rehabilitation strategy adopted by Kidston for their surface waste rock dump was to selectively place the mineralised material within a 50 to 60 m wide side encapsulation of fresh barren waste rock, and to construct an innovative store and release cover comprising oxide waste over the top of the dump revegetated with native trees, shrubs, and grasses. The dump rehabilitation aims were to prevent the exposure of the mineralised waste rock to rainfall infiltration incident on the free-draining fresh barren rock angle of repose slopes, and for the top cover to minimise the net percolation of incident rainfall into any underlying mineralised waste rock, which it has been demonstrated to achieve. For the surface tailings storage facility, the upper exposed layer of tailings oxidised and the oxidation products were largely leached by rainfall infiltration, resulting in a slightly alkaline pH, and rendering the tailings surface suited to direct revegetation with the addition of fertiliser and initial irrigation. The tailings also have a relatively low permeability. Both the low permeability of the tailings and the revegetation with native trees, shrubs and grasses serve to limit the net percolation of rainfall. Genex Power Limited purchased the Kidston mine site in 2016 with the aim of converting it to a Renewable Energy/Battery Hub, including a Solar Farm, on the surface tailings storage facility, and constructing a Pumped Storage Hydro Project, taking advantage of the two open pits. These facilities are described in the paper, which also provide the opportunity for the long-term management of the former mine site.

Keywords: post-closure repurposing, rehabilitation, slope treatment, tailings storage facility, waste rock dump

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