4. Lab-scale solvent extraction studies

Lab-scale solvent extraction studies focus on the development of a solvent extraction process to selectively separate targeted metals ions from a feed solution, for instance produced during a previous leaching study. First, several extractant systems are screened based on the composition of the feed solution and the targeted metal ions, using small scale shaking tests. The extractants can either be commercially available or tailor-made in our synthesis lab. The performance of the extractant is evaluated based on the distribution ratio, percentage extraction and separation factors to gain insight into the amount of extraction and the selectivity of the system for the targeted metal ions. The best performing extraction system is further explored by optimisation of several extraction parameters, including shaking time, temperature, extractant concentration, salt concentration, pH, phase ratio, … The same procedure is followed for the selection of a suitable stripping agent. The best stripping agent is selected based on the system and the results of a screening study. Next, the process parameters are optimised to achieve full recovery of the extracted metal ions. Furthermore, the stability and reusability of the extraction solvent is investigated.

Available equipment: thermoshakers, separatory funnel shaker, magnetic stirring plates with heating blocks, centrifuge, ICP-OES, microwave digester, TXRF