Tailings dewatering : thickening followed by filtration

Abstract

Every year, the mineral processing industry produces a significant amount of tailings that are difficult to effectively manage. Tailings dewatering is a very effective method of tailings management, which helps recover process water and safely store the tailings. Dewatering the tailings reduces the volume of tailings which in turn reduces the risks associated with dam failure and environmental degradation. Thickeners can process large volume of tailings, produce dense underflow and clear overflow liquor. Different kinds of flocculants are added in thickening operation to enhance dewatering of tailings. Flocculant addition increases the settling rate of solids, promotes consolidation, and clarifies the overflow liquor. Underflow produced from thickener can either be disposed directly to the tailings storage facility or filtered to create cakes with less residual moisture for dry stacking. Pressure filters can produce dry cakes, which can be transported by trucks or conveyor belts for ‘dry-stacking’. Dewatering tailings reduces the capital and operating costs, as well as the demand for natural water consumption.

The main aim of this thesis was to study the dewatering of two different tailings. First, the tailings were thickened with addition of flocculant, and the resulting underflow was filtered. Additionally, the effects of various flocculant doses on underflow density, overflow clarity, filtration capacity and cake moisture were studied.