Automation of membrane based solvent extraction unit for Zr and Hf separation

Abstract

In recent years, research into metal ion solvent extraction using hollow fibre membranes has grown. Current studies generally use an analogue controlled experimental setup. Although the analogue system is sufficient for initial proof of concept studies, it does lack the accuracy and repeatability to advance this technology to the next step of commercialization. The aim of this study was therefore to design and construct an automated membrane based solvent extraction system for use in Zr and Hf extraction research. The objective was to attain independent automated control of flow rate and pressure, while improving the accuracy and repeatability of extraction results. Flow rate and pressure were controlled using PID control algorithms and optimized using the Cohen-Coon tuning method. After optimization, a case study for the extraction of Zr and Hf, using Cyanex 301® as extractant, was conducted. It was shown that the automated system was able to accurately control the flow rate and pressure. This improvement of accuracy led to highly reproducible extraction results with the standard deviations varying by less than 1.2%. From this it can be concluded that the automated system was successfully implemented with independent control of the flow rate and pressure