Extraction of Rare Earth Sulfates Using Saponified HEH (EHP) with Mg²⁺ Ion as Barrier Agent

Abstract

As one kind of the most important intermediate materials in rare earth (RE) industry, RE sulfates have been considered difficult to be extracted and separated directly by saponified extractants due to the dissolubility of RE double sulfate of cation. By introducing a barrier agent such as Mg²⁺ ion in the present work, we proposed and developed a process to extract RE cations in sulfate medium with saponified HEH(EHP). Further, a selection criterion of the barrier agent was discussed. The results have revealed that the natural distribution of the univalent ion , RE³⁺ and Mg²⁺ ions, as determined by their extraction sequence in the cascade, hinders the contact between cation and RE ions, and thereby RE double sulfate precipitate does not form during the extraction. Consequently, the study can provide us a strong possibility for extracting and even separating RE using saponified extractants directly from sulfate solution in no need of any transformation of the RE salts employed.

Keywords:

• barrier agent
• extraction
• rare earth
• saponification
• sulfate system

ACKNOWLEDGEMENTS

The work was supported by the High Technology Research and Development Program of China (863) (2010AA03A405); and supported by the National Basic Research Program of China (973) (2012CBA01200).