Optimization of filtered tailings deposition and reclamation for improved physical and chemical stability

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Recent tailings dam failures at Mount Polley, Samarco, Cadia Valley and Brumadinho mines have deeply disrupted the conventional tailings deposition paradigm. New approaches such as filtered tailings deposition are now actively considered and recommended by most guidelines to improve the physical stability of tailings storage facilities (TSF). Dewatering tailings has, indeed, many advantages over traditional slurry tailings, and contributes to reducing geotechnical risk and consequences of dam failures. However, several uncertainties, and in particular the interactions with the atmosphere and the risk for contaminated mine drainage generation, have somewhat slowed down the application of the technique so far, especially in Canada. Also, in practice, relatively limited research has been conducted on filtered TSF long-term behaviour and reclamation, and most of the experience in the field was gained while already operating. Dry stacking would, however, significantly benefit from better planning, as time is the most critical factor controlling filtered tailings hydrogeotechnical and geochemical behaviour. The concept of "Designing for closure" has thus become more relevant than ever. The main objective of the proposed DG research program is therefore to develop solutions and optimize the planning of reactive filtered tailings disposal to better control their hydrogeochemical and geotechnical stability in the short and long term. More specifically, the research program will be divided into two main complementary axes: (1) Optimization of filtered tailings deposition to reduce the risk of acid mine drainage (AMD) generation during operations (considering operational constraints); (2) Development of innovative solutions for temporary and final reclamation of filtered TSF. The research program will be highly multidisciplinary and will provide innovative solutions for the sustainable disposal and reclamation of filtered TSF. The research will be performed through HQP training (3 PhD, 3 MSc and 2 UG) who will become tomorrow's experts in the field. Equity, diversity, and inclusion will be central in the HQP training plan. The research program will include laboratory tests, field work, and advanced numerical simulations, and will contribute to developing and adapting innovative methodological approaches to mining environment. This research will improve knowledge about short- and long-term hydrogeochemical behaviour of filtered tailings. Research outcomes should be of interest for many Canadian mines which consider dry stacking as a way to decrease the geotechnical risks but hesitate to take this path because of uncertainties and lack of technical solutions to tackle acid mine drainage. Developing filtered tailings disposal in Canada would contribute to reducing the risk of TSF dam failures in the future, thus improving the safety of the neighbouring communities, the protection of the environment and the wealth of the society in general.