Separation of Hf(IV)–Zr(IV) in H2SO4 solutions using solvent extraction with D2EHPA or Cyanex 272 at different reagent and metal ion concentrations

In order to produce nuclear reactor grade zircon metal from zircon sand, it is important to develop a process that can selectively extract Hf(IV) over Zr(IV). To this end, the extraction and separation from sulfuric acid solutions (2–6 M) of both of these metal ions were investigated with respect to their concentration ratio. When Hf(IV) was selectively extracted using either Cyanex 272 or D2EHPA, D2EHPA was observed to achieve a higher extraction percentage. With D2EHPA, the extraction percentage for both metals decreased as the concentration of sulfuric acid increased, and the use of a lower concentration of extractant in a stronger solution of sulfuric acid led to a higher separation factor between the two metals. A minimum separation factor of 8 was obtained, even at a metal ion concentration ratio of 100, and within the metal ion concentration ratio presented above, it was possible to separate Hf(IV) over Zr(IV) by utilizing D2EHPA for extraction.