Environmental risk mitigation through concurrent disposal of tailings and mine waste rock at the Minago project in north-central Manitoba, Canada

Authors: Zivkovic, A; Mchaina, D; Henderson, M; Matich, MAJ Paper is not available for download Contact Us

DOI https://doi.org/10.36487/ACG_rep/1008_35_Zivkovic

Cite As:
Zivkovic, A, Mchaina, D, Henderson, M & Matich, MAJ 2010, 'Environmental risk mitigation through concurrent disposal of tailings and mine waste rock at the Minago project in north-central Manitoba, Canada', in R Jewell & AB Fourie (eds), Mine Waste 2010: Proceedings of the First International Seminar on the Reduction of Risk in the Management of Tailings and Mine Waste, Australian Centre for Geomechanics, Perth, pp. 417-430, https://doi.org/10.36487/ACG_rep/1008_35_Zivkovic



Abstract:
The Minago Project, owned by Victory Nickel, is located in the north-central part of the Province of Manitoba, Canada. The site is perennially flooded and is covered with peat (muskeg), which overlies a variable thickness of hard and then soft clay underlain by dolomite bedrock. The site climate is characterised by warm wet summers, and cold and dry winters. The project, which is completed to the feasibility level design, will comprise of an open pit mine producing nickel ore, frac sand, dolomite, granitic rock, and ultramafic waste rock. The leachates from the dolomite and the granitic rock units are not expected to raise any environmental concerns with respect to acid rock drainage and metal leaching (ard/ml). however, ultramafic units are considered as potentially acid generating and metal leaching (PAG/ML). During initial studies of on-land disposal, three separate waste rock dumps for the ultramafic, granite and dolomite waste rock were considered. The ultramafic waste rock dump included a perimeter effluent collection system and post closure treatment in-perpetuity. This was not acceptable to the company and as such a new approach was required. The key objective of subsequent approach was to mitigate environmental risks related to the disposal of PAG/ML ultramafic waste rock. To meet this objective, a tailings and waste rock management facility (TWRMF) was developed to encapsulate the PAG/ML ultramafic waste rock with tailings in a single repository using a novel concurrent disposal approach. A review of published precedents for co-disposal of waste rock and tailings was carried out. Although a number of studies including laboratory/field-scale tests have been described in the literature, the results of the review confirmed a lack of direct precedent for efficient long-term co-disposal applicable to the Minago site-specific conditions. The development of the TWRMF disposal scheme draws upon selected components of precedents from the authors’ experience. It is supported by analyses required to confirm technical feasibility. There will be an emphasis on optimisation during detailed design and operational planning. Mitigation of environmental risks will be achieved by minimising ARD/ML potential by partially submerging the waste rock during operation, ultimately achieving full submergence of a combined waste rock and tailings mass, and controlling seepage to tolerable limits in the long-term. Field trials and a comprehensive instrumentation and monitoring program are planned. This paper focuses mainly on the environmental issues involved and the selected disposal scheme.

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