Passive and active treatment of contaminated mine water

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Mining industry is essential contributor to a strong Canadian economy, but produces large volumes of waste, and uses critical resources such as water and energy. Responsible management of contaminated water is a major challenge in mining and three priorities can be identified: 1) development of sustainable treatment technologies; 2) control of the residual salinity after treatment; 3) safe handling and the recovery of potential economical elements from the sludge produced. The research proposed in this incrementally innovative 5-year program will be centered on passive and active treatment of mine effluents, with three long-term objectives: O1) Improve the performance of passive treatment for mine effluents, in cold climate and at high salinity, using on-site available materials, to reduce transportation costs and footprint impact of rehabilitation; O2) Optimize the performance and valorization of modified natural materials and industrial residues in the prevention and passive/active treatment of mine water; O3) Improve the knowledge and active treatment efficiency of REE (rare earth elements) in mine water. In passive treatment, through O1 and O2 (partially), two projects are planned: Project 1.1 [PhD1, UG1] Performance of passive treatment for saline mine effluents in cold climate; Project 1.2 [MSc1] Long-term efficiency of modified materials as amendment to control mine drainage quality. Project 1.1 will evaluate the performance of peat (raw or after physical, chemical or thermal activation) and of acid mine drainage treatment sludge in pore water polishing from filtered tailings, at low temperature. In project 1.2 the research will focus on the use of modified dolomite and wood ash as amendments to control mine drainage quality. In active treatment, through O2 (partially) and O3, two other projects are planned: Project 2.1 [PhD2, UG2] Treatment of NH3-N (ammonia nitrogen) and residual metals in pre-treated mine effluents and by-products potential valorization; Project 2.2 [MSc2] REE treatment and recovery from mine water using kaolin. Project 2.1 will focus on NH3-N and residual metals removal in mock and actual mine effluents, using natural or wood ash-based zeolites, and an N isotopic balance. Finally, the project 2.2 will focus on REE removal (commodities and contaminants) by sorption and potential recovery, in a parametric study, using kaolin, which proved efficient in preliminary testing. Therefore, the present 5-year research program will allow useful knowledge development on the use of on-site available or modified materials, on the limitation of residual salinity creation, on the potential valorization of contaminated solids generated during mine water treatment, and on the natural water quality as influenced by mine water. Given the increased development of mining in sensitive areas of northern Canada, the spin-offs from this research project will be critical in maintaining Canada as a global leader in sustainable mining development.