Mining for Closure — Design Considerations for UraMin’s Trekkopje Uranium Project

Authors: Limpitlaw, D; Mandziak, T; Macpherson, I Download Paper

DOI https://doi.org/10.36487/ACG_repo/852_25

Cite As:
Limpitlaw, D, Mandziak, T & Macpherson, I 2008, 'Mining for Closure — Design Considerations for UraMin’s Trekkopje Uranium Project', 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. 269-276, https://doi.org/10.36487/ACG_repo/852_25



Abstract:
The Trekkopje Uranium Project, located in the Namib Desert in Namibia, will be a large, shallow open cast mine with a production rate of 100,000 tons of ore per day, at a stripping ratio of 0.23. The scale and location of the project in the sensitive, hyper arid Namib necessitated a cost effective design that minimized impacts on the environment and facilitated closure. Restoring vegetative cover and ecosystem function in a desert setting is difficult, and minimizing the footprint of the mine to start with was adopted as a key design criterion. The low grade ore required a cost effective means of extracting the uranium, and heap leaching was selected as the preferred approach. As a permanent, or dedicated, single lift heap leach pad (HLP) would have covered an area at least as large as the pit, an on-off heap leach pad was selected. Using this method, the crushed ore would be leached on a synthetically lined surface, with the spent ore being returned to the mine, minimizing the disturbance footprint and allowing concurrent reclamation of the mine. The final landforms arising from this approach are closer to the original land surface relative to a permanent HLP, and the total area disturbed is significantly smaller. Other design features intended to assist the mine in meeting the main objectives of reclamation included: long-term slope stability and public safety (including radiological impact mitigation); minimizing environmental impacts; minimizing the total mining land footprint and landscape integration while complying with regulations. In addition, plant rescue missions are mounted to remove rare and endemic plants from the path of mining, and an indigenous nursery is run to supply plants for the rehabilitated areas. Work is ongoing for several key areas of the design, including residues management, ground water impact avoidance, the requirements of the final cover to protect against erosion, intrusion and radiological impact, and future land-use options for the site. This paper is a report on work in progress and illustrates the benefit of integrating environmental considerations into the mine design from the initiation of the process.

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