Efficient recovery of Th and rare earth from radioactive residue leachate using synthesized amide carboxylic acids:...

In this article, the amide carboxylic acid extractants (N-[N,N-di(2-ethylhexyl)aminocarbonyl]methyl)leucine) and NLPL (lauroyl leucine) were synthesized by acylation reactions. A novel recovery process was developed for the leachate of ion-adsorption rare earth ore radioactive waste residue (IREORWR), which includes a fractional extraction of Th using D₂EHAL and an extraction-precipitation of rare earth (RE) using NLPL. D₂EHAL exhibited excellent selectivity and high extraction efficiency for Th. Unlike common RE precipitants, NLPL could quantitatively extract and precipitate RE with larger particle sizes and faster solid-liquid separation rates. After five stages of extraction and two stages of scrubbing, the Th concentration in the radioactive waste residue leachate was reduced from 37.1 mg/L to 0.839 mg/L. Following the NLPL extraction-precipitation enrichment, the RE concentration reached approximately 195 g/L, meeting the industrial requirement for subsequent RE separation.