Recovery of Rare Earth Elements from Coal Fly Ash with Betainium Bis(trifluoromethylsulfonyl)imide: Different Ash Types and Broad Elemental Survey

Previously, proof-of-concept studies have demonstrated that rare-earth elements (REEs) can be preferentially extracted from coal fly ash (CFA) solids using a recyclable ionic liquid (IL), betainium bis(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]). When the suspension of aqueous solution—IL-CFA—is heated above 65 °C, majority REEs will separate bulk in and partition to IL phase. Acid stripping removes regenerates for reuse additional extraction cycles. The objective this study is showcase applicability effectiveness optimized method recover various CFAs. Six CFA samples with different characteristics (feed basins, beds, collecting points) classifications (Class C Class F) were examined. process performance was evaluated broad range (33 total), including 15 REEs, two actinides, six elements, 10 trace metals. Results confirmed good recovery total (ranging 44% 66% among samples) process’ high selectivity over other elements. Sc, Y, Nd, Sm, Gd, Dy, Yb consistently showed leaching partitioning into phase, an average efficiency ranging 53.8% 66.2%, while greater variability samples. Some amounts Al Th co-extracted Fe co-extraction successfully limited by chloride complexation ascorbic acid reduction. These results indicated IL-based REE-CFA maintain REE across types CFA, therefore providing promising sustainable strategy wastes.