CFD Modelling of Flow Field and Mixing Characteristics in a Flotation Cell

Flow field and mixing characteristics in a flotation cell not only significantly affect particle suspension, reagent distribution and froth stabilization, but also determine the flotation efficiency. This work aims to obtain a detailed understanding of the water flow in a flotation cell through combined use of single-phase computational fluid dynamics (CFD) model and advanced laser measurement using particle image velocimetry (PIV). The CFD model has been set up to simulate a 1.58 m³ industrial Wemco flotation cell. Following model validation using PIV measurement data taken at several representative planes, the flow dynamics in the flotation cell have been analysed in terms of flow pattern and velocity. The results show that good agreement is achieved between predicted and measured time-averaged flows, with three annular recirculation zones observed. In the mixing characteristics simulations, tracer injection was used to investigate the mixing time, residence time distribution and local flow patterns. Mixing time is found to decrease with increase in rotor speed, proportional to the inverse of speed, as expected for fully turbulent flow. As the through-flow rate increases, the residence time decreases, proportional to the inverse of flow rate, as expected. The position of the cell tailings underflow outlet has a significant influence on the lower recirculation zone, altering the flow patterns and the extent of recirculation within the system.