The U.S. Department of Energy has identified rare earth element supplies as vulnerable for US economic security due to their unreliable domestic supply. Rare earth elements (REEs) are critical components in a variety of advanced technology such as electric vehicles, industrial magnets, and communication devices. Therefore, it is important to investigate alternative sources of REEs. Traditional REE extraction requires large amounts of acids and organic solvents. Our process may provide an organic solvent-free and environmentally friendly method of extracting and recovering REEs. In this research we investigated coal fly ash (CFA) as a potential source. Moreover, we developed a novel material that can extract REEs from CFA leachate with preference toward the heavy REEs. We used column experiments to concentrate REEs in the media before eluting with an acidic solution. The final REE concentrate was precipitated and calcined to yield rare earth oxide powder as the final product. Preliminary experiments produced REE oxide powders ranging from 6-12% (wt/wt) with an enrichment of 300x. The main challenge with the CFA leachate is its content of other trivalent elements like iron that competes with the sorption of REEs leading to reduced efficiency. Therefore, a pre-filtration step to purify the leachate solution could enhance the media capacity and leading to higher enrichment of REE oxide powder. Our preliminary results showed a prefiltration step decreased Fe and Al in the leachate solution before advancing to the REEs concentration steps. This process is a promising application of green chemistry for extracting valuable materials from a waste product.

Extraction and concentration of rare earth elements from coal fly ash

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.