Solvent extraction separation of La from chloride solution containing Pr and Nd with Cyanex 272

In order to develop a process to separate La from Pr and Nd, solvent extraction experiments have been done. A synthetic chloride leach liquor of monazite after NaOH digestion was used in this study and its chemical composition was La—781 ppm, Pr—119 ppm, and Nd—333 ppm and initial pH of 4.94. Among the extractants tested in this study (Cyanex 272, D2EHPA, PC88A, and Cyanex 301), Cyanex 272 exhibited the best extraction affinity toward Pr and Nd than La. Saponification of Cyanex 272 had some beneficial effect on the separation of La from Pr and Nd. As the saponification degree of Cyanex 272 increased to 50%, the percent extraction of La was depressed to zero and thus it was possible to separate La from the solution. Batch simulation of the counter-current extraction studies with saponified Cyanex 272 confirmed that the extraction percentage of La, Pr, and Nd was 4.9%, 96.6%, and 98.7%, respectively. The co-extracted La in the loaded organic was scrubbed with pure Nd solution and stripping of Pr and Nd from the loaded organic phase was achieved with 1 M HCl.

► Solvent extraction was done to separate La from Pr and Nd from chloride solution.
► Cyanex 272 was effective in separating La among the tested extractants.
► Extraction of La was reduced with increasing saponification degree of Cyanex 272.
► La was completely separated by scrubbing loaded Cyanex 272 with pure Nd solution.
► A separation condition of La from Nd and Pr was demonstrated at an initial pH of 4.94.