Effect of interparticle interactions on the yield stress of thickened flocculated copper mineral tailings slurry

Abstract

Gravity thickening by deep cone thickener is popularly applied in cemented paste backfill, which is essential for tailings management and green mining. To avoid rake bogging, high concentration and high flowability are required for thickened tailings slurry. These properties depend critically on the yield stress of the slurry. The yield stress, in turn, can be influenced by the flocculant dosage and the acidity (pH) that form the flocculation condition. Experiments have been performed to eventually quantify the dependence of yield stress on these two variables. The yield stress test of flocculated and thickened copper mineral tailings slurry, and the analysis of flocculant adsorption, were conducted at different pH values and flocculant dosages. It turns out that the amount of flocculant adsorbed on the tailings particles surface has a maximum with respect to pH but increases with the increasing flocculant dosage. In turn, the amount of flocculant adsorbed affects the yield stress, a macroscopic property of the slurry, through the total interactions (microscopic) between polymer-coated tailings particles. Bridging interaction is essential for total interactions. It is obtained that the yield stress varies analogously to the absolute of the minimum value of the total interactions at different pH values and flocculant dosages. Therefore, interparticle interactions should be adjusted by control pH and flocculant dosage to achieve high-concentration and high-flowability underflow to avoid rake bogging in a deep cone thickener.