Closure considerations while operating a tailings management facility in northern Ontario, Canada

Authors: Donato, R Download Paper

DOI https://doi.org/10.36487/ACG_rep/1152_103_Donato

Cite As:
Donato, R 2011, 'Closure considerations while operating a tailings management facility in northern Ontario, Canada', in AB Fourie, M Tibbett & A Beersing (eds), Mine Closure 2011: Proceedings of the Sixth International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 349-356, https://doi.org/10.36487/ACG_rep/1152_103_Donato



Abstract:
Vale Canada Limited (Vale) owns mining and mineral processing facilities in the City of Greater Sudbury that have been operating since the late 1800s. Central operations include mining, milling, smelting and refining of sulphidic ore to produce principally nickel and copper metal. In 1989, milling was consolidated to the Clarabelle Mill that uses the Central Tailings Area (CTA) to manage tailings. The CTA has been in operation since the late 1930s and closure is not expected for several decades. The CTA covers approximately 28 km2, making it one of the largest and oldest operating tailings management facilities in North America. Given the sulphide bearing ores and net surplus precipitation climate of the Sudbury area, the CTA ponds are a key to managing Acid Rock Drainage and flow control within the central operations. Waste water and runoff from most of the central operations is also pumped to the CTA ponds. These additional sites add 25 km2 to the area serviced by Vale’s Copper Cliff Water Management System. This water management system will be required for the current life of operations (until approximately year 2050) and possibly for many decades following closure. Mine closure planning became mandatory under Ontario law in 1991. The original CTA closure plan was submitted to the Ontario Ministry of Northern Development and Mines in 1998 and was updated in 2001 and 2006. Ongoing review of the CTA operations and associated capital projects typically includes operational and/or project evaluation in the context of the CTA’s closure objectives to ensure sustainable use of the facility while meeting operational needs. A case study of Vale's CTA is presented illustrating how tailings management operational aspects incorporate the facility's fundamental closure objectives. The operational aspects discussed in this paper are minimised acid rock drainage, surface water management, tailings filling planning, static and seismic stability and progressive reclamation. The aspects of tailings management discussed in this paper are offered as an example of best practice, in particular to operators of large, upstream constructed tailings management facilities when closure is not anticipated for many decades. This paper also illustrates the merits of considering facility closure objectives on a continual and consistent basis during operations.

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