Grant: Discovery Grants Program - Individual

In humid climates, problematic mine wastes are often reclaimed using covers with capillary barrier effects (CCBE) or low saturated hydraulic conductivity cover (LSHCC). However, these techniques can require vast amounts of natural materials and result in more land being disturbed. One more sustainable alternative is to use waste produced during the treatment of acid mine drainage, such as water treatment sludge or sludge-slag, to reduce or entirely replace some of the natural materials in engineered covers. However, the properties of these materials are not fully understood, with potential issues including chemical instabilities and freeze/thaw (FT) effects that could produce preferential flow paths and decrease cover performance. This research program builds on the research program initiated in the applicant's previous DG on mine site reclamation. More specifically, the overarching long-term objective of the proposed research program is to develop the design strategies for effective and low-cost reclamation of tailings storage facilities and to improve the performance prediction of cover systems that control acid mine drainage. To achieve this goal, the research program aims to achieve two main themes: A) Development of techniques for reclaiming mine waste and integrating mining by-products into the reclamation process of mining sites in a sustainable manner, and B) Improving the methods used in the prediction of hydrogeological properties of mining by-products. In theme 1, sludge-slug, sand, clay, and non-reactive tailings will be sampled. Then different mixtures will be prepared and submitted for more detailed characterizations, including hydrogeological properties and geotechnical properties. The effect of freeze-thaw cycles on the hydraulic properties of the materials will be evaluated using a temperature-controlled chamber. Results will be compiled and analyzed to develop a model for the prediction of Wate retenction curves, saturated hydraulic conductivity, and compaction point parameters for these mixed materials. In theme 2, mixtures materials in first will be tested in laboratory-scale kinetic from the column tests to determine if the mixed materials are chemically suitable for use in the construction of an engineered cover. Then, experimental columns and field experimental cells will be built to evaluate the capacity of mixtures to act as the moisture-retaining layer in a CCBE and as hydraulic barrier in LSHCC. Field measurements will be used to calibrate numerical models and simulations will be performed under natural climatic conditions to test the long-term cover behaviours. Work in this proposal will be performed by HQP who will become much needed specialists that will help the industry produce metals while reducing its environmental impacts These HQP will be well equipped to design effective covers that meet industrial, governmental, and community requirements.