Consolidation behavior of various types of slurry tailings co-disposed with waste rock inclusions: a numerical study

The co-disposition of mine tailings and waste rock in tailings storage facilities (TSFs) could contribute to increase the consolidation rate and decrease long-term settlement of tailings. Non-linear change of tailings properties during the filling process and interaction between tailings and waste rock inclusion (WRI) are critical to mechanical analysis but can, however, be complicated to simulate. The question of net volume gains or losses of tailings was also raised. In this study, fully coupled analysis which considered continuous variation of hydraulic conductivity and stiffness of tailings were performed to assess the evolution of consolidation of various tailings types in the presence of WRI. Effects of volume ratio of tailings over WRI on the net volume was investigated. Finally, effect of several practical aspects such as filling rates, and instantaneous filling assumption were considered. Results indicated that WRI could increase by 3.3 times the rate of consolidation of tailings. The zone of influence of WRI on tailings consolidation varied for each tailings. Using updated properties showed significant differences compared to models with constant values. The application of WRI can reduce volume available for the storage of tailings and net volumetric change due to settlement of the tailings with or without WRI could be estimated explicitly. Equations predicting evolution of net volume with the changes in the volume ratio of tailings and WRI were accordingly proposed. WRI effects were more pronounced with the increase of the filling rate. Finally, instantaneous filling assumption had little effect on the simulated rate of consolidation.