The UK Government has committed to building STEP (Spherical Tokamak for Energy Production), a prototype fusion power plant, by 2040, which will use lithium-6 to generate tritium for the fusion reaction. More than 100 tonnes of isotopically pure lithium-6 will be required for its operation, yet there is no large-scale lithium isotope enrichment plant in the Western world.
The historically established process for enriching lithium-6, COLEX (COLumn EXchange), utilises significant quantities of liquid mercury, which has previously resulted in substantial hazardous environmental discharges. Given current and future regulatory requirements, it is very unlikely that this process will be acceptable for deployment. Literature reports indicate that solvent extraction can achieve lithium isotope separation performance comparable to that of the COLEX process. However, this has only been reported at a very small scale and typically for only one extraction stage.
This talk will present recent progress in developing solvent extraction systems for lithium enrichment that can be deployed at a process scale. To facilitate rapid commercialisation to meet the short timescales, this project includes experimental work on back-extraction, solvent degradation, and waste prevention, in combination with pilot-scale solvent extraction over multiple steps. Additionally, an on-line monitoring system to measure the lithium isotope ratios in real-time has been developed. The parallel development of a UK regulatory framework and a lifecycle analysis will also be presented.