Hydrometallurgical Separation Methods

Our research focuses on minimization of the volume of the radiotoxic waste, to safely condition residual waste and to optimize complex and time consuming procedures. This includes also the development of advanced technologies to potentially recover long-lived constituents, such as the minor actinides from highly radioactive spent fuel for a subsequent conditioning in stable matrices. Research on the separation of radionuclides from nuclear waste solutions is based on highly selective hydrometallurgical separation processes.

Hydrometallurgical separation technologies also concentrate the radionuclides destined for geologic disposal into a smaller volume. The main objectives of our research are on the one hand fundamental research on solvent extraction, to improve the knowledge of the chemistry of the radionuclides and the extraction ligands and on the other hand process development involving testing of continuous extraction devices with inactive and with spiked radioactive waste solutions. For a successful separation of specific waste components, a fundamental understanding of the principles of the complexation of radionuclides in aqueous and organic extractant solution is a crucial issue. Research covers the fields of thermodynamics, hydrodynamics and kinetics of liquid-liquid extraction as well as the long-term operation of the solvent (hydrolysis and radiolysis). This includes also recycling and cleaning of the solvent and the management of secondary waste. This knowledge is important to develop multi-scale models to be used in a simulation code, which is an indispensable tool to operate such processes in a safe manner. The flow-sheets are tested and evaluated by comparing them with model predictions.