Metal Recovery from Spent Samarium–Cobalt Magnets Using a Trichloride Ionic Liquid

Abstract

Recycling of samarium–cobalt (SmCo) magnets is essential due to the limited resources of the mentioned metals and their high economic importance. The ionic liquid (IL) trihexyltetradecylphosphonium trichloride, [P666,14][Cl3], which can safely store chlorine gas in the form of the trichloride anion, was used as an oxidizing solvent for the recovery of metals from spent SmCo magnets. The dissolution was studied considering various mixtures of the ILs [P666,14][Cl3] and [P666,14]Cl, solid-to-liquid ratios and different temperatures. The results showed that the maximum capacity of [P666,14][Cl3] for SmCo magnets was 71 ± 1 mg/g of [P666,14][Cl3], in the presence of an extra source of coordinating chloride ions. The maximum loading of the IL could be reached within 3 h at 50 °C. Four stripping steps effectively removed all metals from the loaded IL, where sodium chloride solution (3 mol L–1), twice water and ammonia solution (3 mol L–1) were used consecutively as the stripping solvents. The regenerated IL showed a similar dissolution performance as fresh IL. Oxidative dissolution of metals in trichloride ILs is easily transferable to the recycling of valuable metals from other end-of-life products such as neodymium–iron–boron magnets and nickel metal hydride batteries.

Polyhalogen and Polyinterhalogen Anions from Fluorine to Iodine

“…[203,204] Similarly,aprocess for metal recovery from samarium-cobalt magnets was recently published. [205]…”

Polyhalogen‐ und Polyinterhalogen‐Anionen von Fluor bis Iod

“…[203,204] Über ein ähnliches Verfahren zur Rückgewinnung von Metallen aus Samarium-Cobalt-Magneten wurde jüngst berichtet. [205]…”

From Polyhalides to Polypseudohalides: Chemistry Based on Cyanogen Bromide

“…[24,25] [*] B. [26,28] Because of its severe toxicity combined with ah igh vapor pressure at 25 8 8C( 160 mbar), [29] the use of neat BrCN requires the highest safety precautions.T he stabilization of BrCN in the form of polypseudohalides,a si ni onic liquids,r esults in ar educed vapor pressure.C onsequently, asafer and easy-to-handle substance for applications such as metal recovery [8][9][10] or organic synthesis is obtained. The pseudohalogen BrCN is atoxic compound that is widely used in organic chemistry.…”

“…[1] Their observation was the starting point of the vast chemistry of polyhalogen compounds,which have been studied numerously over the last years. [3,[7][8][9][10] Whereas the polyhalides and their potential applications have been intensively investigated, the chemistry of polypseudohalides is less studied. [3,[7][8][9][10] Whereas the polyhalides and their potential applications have been intensively investigated, the chemistry of polypseudohalides is less studied.…”

“…[2,3] Recent studies of the highly reactive [Br 2 F 7 ] À and [Br 3 F 10 ] À anions [4] as well as the hitherto unknown octahedrally coordinated tridecahalide monoanions [Cl 13 ] À [5] and [Cl(BrCl) 6 ] À [6] have expanded the diversity of structural motifs in polyhalogen chemistry.F urthermore,t he use of polyhalogen compounds as halogenating reagents, electrolytes,a nd ionic liquids has been growing over the last decade. [3,[7][8][9][10] Whereas the polyhalides and their potential applications have been intensively investigated, the chemistry of polypseudohalides is less studied.…”