This review focuses on consolidating the sequential selective element extraction performed in the process intensification equipment known as Centrifugal Contactors (CCs), the unpredicted precipitation that arises, and finally solutions for inhibiting in situ solids formation.

In this work, the GEneralised Multifluid Modelling Approach (GEMMA) is applied to the simulation of liquid–liquid extraction in a Rotating Disc Column (RDC) and a Pulsed Sieve-plate Extraction Column (PSEC). A mass transfer modelling methodology is developed, in which the multiphase flows, droplet size distribution and dispersed phase holdup predicted with computational fluid dynamics are coupled to mass transfer correlations to predict the overall mass transfer. The numerical results for the stage-averaged dispersed phase holdup, Sauter mean droplet diameter and axial solute concentration in the RDC and PSEC agree with experimental observations. The proposed modelling method provides an accurate predictive tool for complex multiphase flows, such as those observed in intensified liquid–liquid extraction, and provides an alternative approach to column design using empirical correlations or pilot plant study.

This work reports the effect of scaling up annular centrifugal contactors (ACCs) upon the residence time distribution and the efficiency of extraction of uranium. The experiments were carried out in a multi-scale ACC platform of three ACCs with rotor diameters of 12, 25, and 40 mm. To enable direct comparison across all three scales of ACC, the residence time distributions were acquired by injecting dye into the solvent phase at a constant relative volume related to the ACC liquid holdup. Across all scales and flowrates, there was little difference in residence time distribution (<6 residence volumes), except for the smallest 12 mm rotor diameter ACC with a high solvent/aqueous feed ratio, which required 12 residence volumes, potentially due to internal circulation in the annulus. At low flowrates, the stage efficiency in all cases was >95%, and it improved further in larger rotor diameter ACCs.