Separation of zirconium and hafnium from nitric acid solutions with LIX 63, PC 88A and their mixture by solvent extraction

Abstract

The separation of Zr and Hf is of importance in the production of nuclear reactor grade metals. Solvent extraction experiments were performed to separate the two metals by using LIX 63, PC 88A and mixture of PC 88A and LIX 63 in the nitric acid concentration from 0.5 to 4M. Zr was selectively extracted over Hf by the above extractants. Of the two extractants, PC 88A led to higher extraction efficiency of the two metals while LIX 63 resulted in an outstanding separation factor of 186 between Zr and Hf. The mixture of LIX 63 and PC 88A had some positive effect on the extraction of the two metals but the separation efficiency of the mixture was not as high as single LIX 63. The solvent extraction reaction of Zr and Hf by LIX 63 at 2M nitric acid solution was identified by applying a slope analysis method. Selective extraction of Zr over Hf by LIX 63 was verified by varying the initial concentration ratio of Zr to Hf from 1 to 50. An optimum concentration ratio of LIX 63 to Zr was proposed to get higher separation factor. Effective stripping of Zr and Hf from loaded LIX 63 was possible by using sulfuric acid solution.