Industrial & Engineering Chemistry Research, Vol.39, No.10, 3907-3911, 2000
Selective extraction of Y from a Ho/Y/Er mixture by liquid-liquid extraction in the presence of a water soluble complexing agent
The selective extraction of Y from Ho/Y/Er solution by liquid-liquid extraction using (2-ethylhexyl)phosphonic acid mono(2-ethylhexyl) ester (EHPNA), in the presence of a water-soluble complexing agent (ethylenediaminetetraacetic acid, EDTA), has been investigated. The extraction behavior of the ternary system for Ho, Y, and Er, in the presence of EDTA can be expressed using extraction equilibrium formulations, applying for the EDTA free system and consistent with the assumption that the rare-earth metals, when complexed with EDTA, do not take part in the extraction (masking effect). The extraction of Ho and Er in the presence-of EDTA is suppressed when compared to that of Y because of the masking effect, and the selective extraction of Y is enhanced. Simulation studies for the separation of Y from a Ho/Y/Er mixture, by the use of a countercurrent mixer-settler cascade, show that the separation is enhanced by the addition of EDTA in both extraction and scrubbing sections.