Performance of Various Extractants for Zirconium and Hafnium Separation by Solvent Extraction

Solvent extraction has always been the main Zr/Hf separation method. However, all the existing industrialized Zr/Hf solvent extraction separation methods, namely MIBK(methyl isobutyl ketone)-HSCN, TBP(tributylphosphate)-HNO3 and TOA(trioctylamine)-H2SO4 have shortages. To realize Zr/Hf environment-friendly and efficient separation, novel extractants have always been studied. This paper summarized the studies of extractants on Zr/Hf separation since 2000. All the extractants were classified into three groups according to their structural characteristics. They were neutral extractants, acidic extractants and amine-based extractants. The neutral extractants included the ketone DIBK (diisobutyl ketone) and the trialkylphosphine oxides TOPO(trioctyl phosphine oxide)/Cyanex 921, Cyanex 923 and Cyanex 925. The acidic extractants included the organophosphoric/phosphonic/phosphinic acids P204, P507 and Cyanex 272, the thiosubstituted phosphinic acids Cyanex 301 and Cyanex 302, the hydroximic acids LIX 63, LIX 84-IC and the carboxylic acid Versatic acid 10. As to the amine-based extractant, it refered to all the extractans that contained amino group in this paper, concluding the quaternary ammonium salt Aliquat 336, the trialkylamines Alamine 300/TOA, Alamine 336, Alamine 308 andtri(2-ethylhexyl)amine (TEHA), the neutral organophosphorous compound containing the amino groupbis(2-ethylhexyl)-1-(2-ethylhexylamino)propylphosphonate (BEAP), the amido podand N,N,N',N'-tetraoctyldiglycolamide (TODGA)and the isoxazolones 3-phenyl-4-benzoyl-5-isoxazolone (HPBI), 3-phenyl-4-(4-toluoyl)-5-isoxazolone (HTBI)and 3-phenyl-4-(4-fluorobenzoyl)-5-isoxazolone (HFBTI). Their Zr/Hf separation performance and the main advantages and disadvantages were summarized. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.