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Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride

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EaStCHEM School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, UK
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School of Geosciences, University of Edinburgh, Edinburgh EH9 3FE, UK
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Author to whom correspondence should be addressed.
Metals 2020, 10(3), 346; https://doi.org/10.3390/met10030346
Received: 19 February 2020 / Revised: 3 March 2020 / Accepted: 4 March 2020 / Published: 6 March 2020
The recycling of tantalum (Ta) is becoming increasingly important due to the criticality of its supply from a conflict mineral. It is used extensively in modern electronics, such as in capacitors, and so electronic waste is a potentially valuable secondary source of this metal. However, the recycling of Ta is difficult, not least because of the challenges of its leaching and subsequent separation from other metals. In this work, we show that Ta(V) halides, such as TaCl5 and TaF5, which can potentially be accessed from Ta metal upon acid halide leaching, can be recovered by solvent extraction using a simple primary amide reagent. The need for high halide concentrations in the aqueous phase implies the formation of the hexahalide salts [TaX6] (X = F, Cl) and that an anion-swing mechanism operates. While extraction of the fluorides is poor (up to 45%), excellent extraction under chloride conditions is found (>99%) and presents an alternative route to Ta recycling. View Full-Text
Keywords: tantalum; solvent extraction; WEEE; recycling; chemical separation tantalum; solvent extraction; WEEE; recycling; chemical separation
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Kinsman, L.M.M.; Crevecoeur, R.A.M.; Singh-Morgan, A.; Ngwenya, B.T.; Morrison, C.A.; Love, J.B. Tantalum Recycling by Solvent Extraction: Chloride Is Better than Fluoride. Metals 2020, 10, 346.

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