Resume/ Abstract:

Traditional mining site reclamation involves building cover systems to reduce oxygen flow and/or water infiltration into the site, to prevent acid mine drainage (AMD). These systems require significant amounts of materials with specific hydrogeotechnical properties, and their extraction and transport lead to environmental and economic costs. New reclamation methods should emphasize the valorization of mine tailings as cover materials. One option is the low carbon cementitious treatment of tailings, which can create a low-permeability surface layer in existing tailings storage facilities (TSFs). This treatment aims to enhance physical properties and immobilize contaminants within the cement matrix.

This research evaluated the effectiveness of adding general-use (GU) cement and slag-based cement at 5% or 7% binder dosages on the unconfined compressive strength (UCS), hydraulic conductivity, and oxygen consumption of cemented tailings. Reactive tailings from Raglan Mine and weathered tailings from Joutel and Manitou sites were tested. The experiment results showed that for Raglan and Joutel tailings, slag-based cement was more effective than GU in reducing hydraulic conductivity and increasing UCS above 1 MPa after 28 days of curing. However, for Manitou tailings, the paste pH value and pore water composition seem to affect the hydration process of binder. For these tailings, with a paste pH of 2.58, GU was more effective. Adding 5% lime kiln dust, as an alkaline additive, to slag-based cement improved short-term mechanical strength. The addition of such an alkaline material raised the pH value to a sufficient alkaline level, making cement hydrates more stable. Mineralogical analyses confirmed these observations.

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Mlle. Audrey Jalce