Mixer-settlers typically contain an impeller mounted on a shaft, and optionally it can contain baffles. In this study, the effect of the number of baffles on the separation characteristics of the system, and the effect of blade width and inlet velocity on baffles number have been investigated. CFD models in MPflow are developed to predict the separation characteristics.

The development of solvent extraction mixer settlers aims at achieving clean phase separation, minimizing the loss of the reagents and decreasing the surface area of the settlers. The role of baffles in a mechanically agitated vessel is to ensure even distribution, reduce settler turbulence, promote the stability of power drawn by the impeller and to prevent swirling and vortexing of liquid, thus, greatly improving the mixing of liquid. Inserting the appropriate number of baffles clearly improves the extent of liquid mixing. However, excessive baffling would interrupt liquid mixing and lengthen the mixing time. CFD provides a tool for determining detailed information on hydrodynamics which is required for modelling sub-processes in mixers.