SOLVENT EXTRACTION OF LANTHANiDES AND YTTRIUM FROM NITRATE SOLUTIONS WITH CYANEX 923

摘要

The extraction of lanthanides (La ～ Lu except Pm) and yttrium from nitrate solutions with Cyanex 923 in heptane has been systematically investigated. The extraction equilibrium constants and mechanism have been determined. The separation factors of lanthanides and yttrium from nitrate solutions have been evaluated and it has been found that their separation factors with purified Cyanex 923 are different from those with non-purified Cyanex 923. Also the dependence of temperatures on the extraction of lanthanides and yttrium has been studied with purified and non-purified Cyanex 923 and the thermodynamic parameters such as free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) have been calculated. The results show that temperature significantly affects the separation of lanthanum and yttrium from rare earths. The well-regulated changes of these parameters with increasing atomic number of rare earth elements take place. The results of the separations with Cyanex 923 of lanthanum from light rare earths and yttrium from heavy rare earths have demonstrated their practicality.