Consolidation of hard rock tailings under positive and negative pore-water pressures: testing procedures and experimental results

Abstract

This paper presents laboratory testing procedures and key results on the consolidation of tailings from hard rock mines under positive or negative pore-water pressures (PWP). Specific experimental protocols have been developed and applied to assess the behaviour of low-density tailings (slurry) using compression tests in instrumented columns. The testing results on saturated specimens with positive PWP are used to determine the primary and secondary compression (consolidation) parameters of the tailings, based on excess PWP and displacement measurements. The compression tests with controlled negative PWP were conducted using two stress paths: vertical loading with a constant (imposed) suction and with a progressively increasing suction. The results from these tests illustrate specifically, for the first time, the combined effects of the net vertical stress and suction on tailings compressibility parameters, and on the evolution of PWP. The experimental procedures and related experimental results presented here can be quite useful for the analysis of tailings consolidation in the field, where both positive and negative PWP can occur.