Intensified extraction of Nd from a Nd/Fe mixture in small channels for NdFeb magnet recycle

The selective extraction of neodymium (Nd) from Nd and mixed Nd/Fe aqueous feeds is studied here, utilizing the 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid [ C 4 m i m ] [ T f 2 N ] with the trioctylphosphine oxide (TOPO) extractant. 100% selective extraction of Nd was achieved in batch equilibrium studies - which was faster for the Nd compared to the Nd/Fe feed. The extraction was intensified by using small channels with 0.5 mm internal diameter. High extraction efficiencies of Nd were achieved, equal to 80% (Nd feed) and 65% (Nd/Fe feed), in residence times of ∼ 37 s. A maximum mass transfer coefficient of 0.1 s − 1 was obtained in 7.5 s for both feeds.