The increasing demand for neodymium (Nd) permanent magnets in electric motors has revived research interest of Nd recovery and separation from other rare earth elements (REEs). Typically, Nd/La separation is necessary for Nd recovery from primary ores and secondary resource recycling. This research used a flat sheet-supported liquid membrane (FSSLM) with different extractant-acid systems to extract Nd from a Nd/La mixture. The recovery and separation of Nd/La with 204P-H2SO4, 507P-HCl, and TBP-HNO3 were discussed. The results showed effective Nd recovery and promising Nd/La selectivity could be achieved in the 507P-HCl system, compared to 204P-H2SO4 and TBP-HNO3. The addition of citric acid to the feed solution was effective for pH buffering but did not improve the Nd transport or Nd/La selectivity. Long-term stability of the 507P-HCl extractant system was demonstrated by extending the processing time from 6 h to 6 days.

This work tested an effective and efficient Nd/La extraction and separation via flat-sheet supported liquid membrane. A microporous polypropylene film was used as the solid support for the liquid membrane and P507 as the extractant. The effect of Nd(III) and La(III) concentration in the feed, the concentration of P507, and acid solution concentration in the stripping phase on Nd and La extraction and separation were studied. The results suggest the extraction of La and Nd increases with the initial pH of the feed solution and P507 concentration. Maximum separation factor of 44.25 was obtained at the low P507 concentration of 5% (v/v). Graphical Abstract

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