Preliminary Study of Lanthanum Separation by the Mixture of TBP-D2EHPA in Kerosene

Solvent extraction of lanthanum (La) was investigated at 28±0.2oC. The equilibrium of mixed rare earth nitrate solution at various concentrations with 1.2 M tributylphosphate (TBP) and 0.3 M di(2-ethlexyl) phosphoric acid (D2EHPA) in kerosene was examined and compared with 50% TBP in kerosene. It was found that the distribution coefficients (kα) of dysprosium (Dy), yttrium (Y), and ytterbium (Yb) were increased. On the other hand, the distribution coefficients of La, (Kα)La, were sightly decreased. Separation factors between Dy, Y Yb and La were increased when organia phase was mixed solvent. Furthermore, most of separation factors tend to be increased when total rare earch concentrations in feed solution were increased. In conclusion, in order to separate La, other rare earchs are transferred to organic extract while only La is kept in aqueous raffinate, and the feed solution with high concentration of total rare earths is preferred