Resume/ Abstract
Filtered tailings contribute to increase geotechnical stability and minimize footprint of tailings storage facilities. Despite their numerous advantages, they can also contribute to increase the risk of acid mine drainage (AMD) generation. From laboratory kinetics tests and multicomponent reactive transport simulations, the critical time, i.e., time tailings can remain exposed before AMD generation starts, was identified as varying significantly with tailings' mineral content and a degree of saturation below 90%. A predictive equation was proposed to estimate critical time. Then, unsaturated and porous media flow simulations, integrating soil-climate interactions were conducted to determine whether the tailings exposure time was critical, during deposition. Different properties of the deposited filtered tailings layers and types of climates were used to assess the variation of the degree of saturation in the deposited filtered tailings and the oxygen flux with depth. Results showed that exposed filtered tailings rarely reached a degree of saturation higher than 90%. However, properly planning tailings deposition can limit AMD risk by limiting oxygen fluxes to the lower layers. Finally, a risk analysis of filtered tailings deposition identified the minimum critical value, considering the tailings storage facility design and operational uncertainties, such as the variability of tailings production. Predicting critical time and the use of a design criterion based on the oxygen flux for deposition planning would ensure the geochemical stability of the filtered tailings storage facility.