Low Temperature Electrochemical Extraction of Rare Earth Metals From Lignite Coal: An Environmentally Benign and Energy Efficient Method

Rare earth elements (REEs) extraction via conventional technologies is exceedingly energy and environmentally intensive. New efficient and sustainable technologies for REE extraction from primary and secondary resources would be extremely beneficial. This research demonstrated a novel low-temperature electrochemical extraction process for extracting REEs from lignite coal ash (LCA) solutions. The LCA contained 17 different REEs with a concentration ranging from 13 to 1645 ppm. The LCA solution mixed with ionic liquid (IL), 1-butyl-3-methylimidazolium tetrafluoroborate (BMITF) was used for extracting REEs at different electrochemical potentials. The ICP-MS analysis confirmed an overall 26% REEs recovery from the LCA solution with 16 out of the 17 REEs successfully extracted from the LCA solution. This study shows an environmentally benign and energy-efficient REE extraction process that is suitable for coal and coal byproducts.