The separation of zirconium and hafnium from (NH4)3Zr(Hf)F7 using amine-based extractants

E.W Conradie

doi:10.17159/2411-9717/2016/v116n10a4

Abstract

The separation of zirconium and hafnium from (NH4)3Zr(Hf)F7 using amine-based extractants

Highlights

The suitability of the amine-based extractants Alamine 336, Aliquat 336 and Uniquat 2280 (10 wt%) for the selective extraction of zirconium (Zr) and hafnium (Hf) from a (NH4)3Zr(Hf)F7 solution was investigated
Zirconium (Zr) and hafnium (Hf) coexist in nature and have similar chemical properties such as ionic radii (0.074 mm for Zr4+ and 0.075 mm for Hf4+) and valence electrons in the outer orbitals. (Xu et al, 2015; Nielsen et al, 2000). Both elements can be found in group 4 of the periodic table, their properties as regards nuclear application differ, the thermal neutron capture cross-section being much higher for Hf than that for Zr. (Purohit and Devi, 1997; Yang et al, 2002) Zr has a high corrosion resistance in acid media, which improves the lifetime of cladding materials in nuclear reactors
There are several processes that are currently in use for the extraction and purification of Zr and Hf, such as the methyl isobutyl ketone (MIBK) process proposed by Fischer and Chalybaeus (Overholser et al, 1960)

Summary

Introduction

The suitability of the amine-based extractants Alamine 336, Aliquat 336 and Uniquat 2280 (10 wt%) for the selective extraction of zirconium (Zr) and hafnium (Hf) from a (NH4)3Zr(Hf)F7 solution was investigated. According to the patent, plasmadissociated zircon is reacted with ammonium bifluoride and an (NH4)3Zr(Hf)F7 complex is formed and isolated for downstream processing, i.e. separation of Zr and Hf. It is the purpose of this research to determine the suitability of amine extractants (Alamine 336, Aliquat 336 and Uniquat 2280) for the separation of Zr and Hf from (NH4)3Zr(Hf)F7 (97 ppm Zr and 3 ppm Hf) in hydrochloric and sulphuric acid solutions (0.01–8 mol/dm3).

Results

Conclusion