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

Rare earth elements (REEs) are critical for the energy transition; however, their ‘green’ credentials are at odds to the environmental damage as part of mining, recovery and processing. Opportunities may exist to recover REEs from uranium tailings as part of the ‘economic rehabilitation’ of tailings storage facilities. [Display omitted] •Water leach able to extract rare earth elements (REEs) from tailings.•More than 10,000 t of REEs could be recovered using an in situ water leach.•REEs recovery using water leach potential exceeds the uranium recovery during initial mining.•Water leaching and recovery of REEs from tailings allows for economic rehabilitation.•In situ extraction from tailings allows for low water, low energy recovery. 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.