The evolution of thickener technology
The first thickeners were simple gravity-based settling tanks. They were slow-settling and needed a large unit area while producing a low underflow density. Improvements to thickener design in the mid-20th century and the introduction of chemical flocculants to promote particle aggregation increased the rate of solid-liquid separation. However, it was not until the 1980s that thickener development took a significant lead forward with high-rate thickeners.
FLS high-rate thickeners were designed to offer mining companies a more compact and cost-effective solution capable of processing larger volumes of slurry while producing a clearer overflow. They feature the improved E-Volute™ feedwell to optimise energy dissipation and solids distribution, while advanced E-DUC® and P-DUC feed slurry dilution systems maximise flocculation efficiency and settling rates. Other benefits include better slimes management.
In recent years, the focus has shifted to maximising the solids concentration in the underflow, leading to the introduction of high-density thickeners. These systems are designed to produce denser tailings with lower water content, enabling easier handling (with suitably designed underflow systems) while reducing the footprint of tailings storage facilities.
FLS Deep Cone® thickeners feature deep side walls, steep cone angles, and a patented inner spiral rake design. These features create and allow effective operation with deeper mud beds, extending mud residency time and increasing solids compaction. Deep Cone thickeners can achieve underflow densities of up to and exceeding 70 wt%, making them ideal for applications where water conservation and tailings management are critical.
A final development of note is the E-CAT™ thickener from FLS, a high-rate thickening solution that combines high-rate thickening and water clarification into a single unit. E-CAT units can handle high throughputs, achieving highly efficient solid-liquid separation to produce a high-clarity overflow, maximising water recovery while minimising water treatment costs.
