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 (TiO2) 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 ScF3 production. From ∼1 m3 of European acid waste containing traces of Sc (81 mg L–1), ∼13 g of Sc (43% yield, nine stages) was recovered as (NH4)3ScF6 with a purity of approximately 95%, demonstrating the technical feasibility of the approach. The production costs per kilogram of ScF3 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.
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IJS, KILJ, NUK, PNG, UL, UM
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
) 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
production. From ∼1 m
of European acid waste containing traces of Sc (81 mg L
), ∼13 g of Sc (43% yield, nine stages) was recovered as (NH
)
ScF
with a purity of approximately 95%, demonstrating the technical feasibility of the approach. The production costs per kilogram of ScF
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.
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Available for:
IJS, KILJ, NUK, PNG, UL, UM
Scandium (Sc) has various technological applications, but the concentrations of Sc in ores are low. Both, the mining of low concentrated Sc and the production of industrial-grade Sc are a heavy ...burden on the environment. Bauxite residue (BR) from alumina production represents one of the major sources of Sc in Europe (Ochsenkühn-Petropulu et al., 1994). The goal of this study is to assess the environmental impacts from cradle to gate of a novel production route developed in the Scandium Aluminium Europe project (SCALE) to extract Sc at concentrations <100 ppm from BR, to concentrate and upgrade it to pure ScF3 and Sc2O3 and ultimately to refine it to an aluminium scandium master alloy with 2 % Sc mass fraction (AlSc2 %). Results show that the global warming potential (GWP), measured in CO2-eq per kg Sc2O3, generated with the novel route is about half the GWP of the state-of-the-art Sc2O3 production from rare earth tailings when applying equal allocation principles. The initial process step to dissolve BR and extract Sc consumes elevated amounts of acid and energy and is responsible for at least 80 % of the route’s total environmental impact. The amount of the generated filter cake (FC) is equal to the amount of the BR input and is a potential resource for cement clinker production. The ecotoxicological study indicates that both FC and BR are slightly ecotoxic.
•Sc recovered from bauxite residue more environmentally friendly then traditional Sc extraction from rare earth tailings.•No additional risk to the environment by transforming bauxite residue into another waste type.•Novel processes for Sc valorization in bauxte residue developed in the Scandium Aluminium Europe project (SCALE).•Novel process route bypasses existing expensive and, in the case of fluorination with gaseous HF.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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