Thermodynamic and application study of complicated extraction system Ce(IV)–HF–H3BO3–H2SO4 using Cyanex 923

Abstract

This article aims to reduce the environmental pollution while maximizing the recovery of REEs as well as associate resource-fluorine (F) from bastnaesite. This paper investigates the extraction equilibrium process and mechanism of Ce(IV)–HF–H3BO3–H2SO4 system using Cyanex 923. Extraction equilibrium process of different systems, including HF–H2SO4, H3BO3–HF–H2SO4, and Ce(IV)–HF–H2SO4, were studied in detail and the corresponding extraction mechanisms were also determined. It is noteworthy that a synergistic effect between B–F and an antagonistic effect between Ce(IV)–F were discovered first in the extraction process by Cyanex 923. Besides, H3BO3 is found to be able to promote the extraction of F in quantitation by Cyanex 923. FTIR and 11B and 19F NMR were adopted to characterize the different loaded organic phase. Based on these results, the extraction mechanism of complicated system Ce(IV)-HF-H3BO3–H2SO4 was further determined. Besides, the effect of H3BO3 on the extraction and stripping of Ce(IV) in complicated system was studied. Moreover, it shows that the addition of H3BO3 has nothing to do with the purity of obtained CeF3 particle from bastneasite liquor in the practical system. Adding H3BO3 into bastnaesite leach liquor, on the one hand, will be beneficial for the recovery yield of Ce and F. On the other hand, it can avoid from environmental pollution caused by emission of F-containing waste water as well as reducing the waste residue.