Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

One of the most critical issues for the mining industry remains the management and safe disposal of the important quantities of solid wastes (mine tailings and waste rocks) produced during the operations. These materials often contain sulfides which can oxidize upon contact with oxygen (air) and water, producing acidic waters with high concentrations of sulfates and heavy metals (known as acid mine drainage, AMD). The proposed research program aims at developing tools and techniques for the disposal of mining wastes in open pits in order to reduce the environmental impact and footprint of disposal sites. This approach is used in a few mining projects but further research is required to fully optimize the technique. The assumptions are that in-pit disposal can be used to limit the risk for AMD generation, improve the overall long term geochemical and geotechnical stability of the disposed materials, stabilize the walls of the pit, reduce the need for building new impoundments or waste rock piles, and improve the aesthetics of the sites. There are, however, several challenges to the method, particularly regarding the geochemical stability of the disposed wastes, the control of water flow and exchanges with the surrounding environment, and the operational aspects of the disposal itself.
The long term objective of the proposed DG research program is to rationalize and optimize the in-pit disposal of reactive mine wastes to better control their hydrogeochemical and geotechnical stability over time. The research program will be divided into two main complementary projects: A. Optimization of the disposal of mining wastes in open pit mines to reduce the risk of AMD generation during operations; B. Long term closure of backfilled open pits. Project A will extend the principle of “Designing for Closure” to in-pit disposal of tailings (A1) and waste rock (A2). The main objective of Project B will be to study the behaviour and performance of engineered cover systems to prevent long term production of AMD in backfilled pits.
The work will be performed through HQP training (2 PhD, 2 MScA and 4 UG). Each project will include laboratory tests (characterization and physical modelling) and field work. Numerical simulations will also be an essential part of the research program.
The proposed DG research program is ambitious and highly original because it aims at developing in-pit disposal by integrating operational and environmental aspects. It will propose robust solutions for optimized disposal. In-pit disposal is becoming more and more important due to the multiplication of surface mines in recent (and probably upcoming) years. There is a strong interest among mining companies for alternative disposal solution that will both fulfil the geotechnical and geochemical stability requirements of disposal sites, and limit the environmental footprint. The proposed research program will answer some of these new challenges.