Numerical Modeling of Tailings Thickening for Improved Mine Waste Management

Abstract

The environmental footprint of mining can be minimized by developing and improving the waste management technologies. Thickening involves the conversion of dilute tailings to paste-like materials with superior engineering and environmental properties. The process of tailings thickening is not well-understood in geotechnical engineering. The primary objective of this paper was to model the dewatering behavior of slurries during thickening. Two separate numerical models were developed using constitutive relationships based on the nonlinear finite strain consolidation theory and on the inclusion of a hindered sedimentation regime in the consolidation theory. In the coupled sedimentation-consolidation model, the transition zone was numerically modeled between a maximum suspension void ratio corresponding to the initial development of a distinct slurry microstructure and a structural void ratio referring to the development of a soil skeleton transferring effective stresses. For the investigated tailings material, sedimentation was found to be complete at em = 8.0 and consolidation was observed to start at es = 6.5. Both of the models closely matched at es <= 6.5 confirming the validity of the coupled sedimentation-consolidation model.

Keywords: mine waste management, tailings thickening, numerical modeling, finite strain consolidation, hindered sedimentation, effective stress, void ratio, hydraulic conductivity