Water-soluble rare earth elements (REEs) recovered from uranium tailings

The global energy transition from fossil fuels to renewable sources poses substantial challenges to increase metal production, including industry-critical rare earth elements (REEs). Environmental and social concerns obfuscate the production of these 'green' metals and only ∼1% of REE demand is met from recycling. This work highlights the potential for the 'economic rehabilitation' of the Mary Kathleen Mine, a relinquished uranium (U) mine with very high (∼3 wt%) total REE concentrations within the tailings storage facility (TSF). Leaching of the tailings revealed that approximately 5% of the REEs are water-soluble, suggesting the possibility for in situ extraction. Using an in situ water leach, the projected total REE recovery is >10,000 t, which would exceed the total amount of U recovered (7,532 t) during the initial mining operation. The proposed in situ recovery would offer a truck-free mine, using solar energy and water recycling technologies to recover REEs from a waste source, reducing environmental contamination.