From Trace to Pure: Pilot-Scale Scandium Recovery from TiO(2) Acid Waste

[Image: see text] Scandium (Sc), declared a critical raw material in the European Union (EU), could face further supply issues as the EU depends almost entirely on imports from China, Russia, and Ukraine. In this study, a tandem nanofiltration-solvent extraction procedure for Sc recovery from titania (TiO(2)) acid waste was piloted and then augmented by antisolvent crystallization. The new process, comprising advanced filtration (hydroxide precipitation, micro-, ultra-, and nanofiltration), solvent extraction, and antisolvent crystallization, was assessed in relation to material and energy inputs and benchmarked on ScF(3) production. From ∼1 m(3) of European acid waste containing traces of Sc (81 mg L(–1)), ∼13 g of Sc (43% yield, nine stages) was recovered as (NH(4))(3)ScF(6) with a purity of approximately 95%, demonstrating the technical feasibility of the approach. The production costs per kilogram of ScF(3) were lower than reported market prices, which underscores a competitive process at scale. Although a few technical bottlenecks (e.g., S/L separation and electricity consumption) need to be overcome, combining advanced filtration with solvent extraction and antisolvent crystallization promises a future supply of this critical raw material from European secondary sources.