The influence of the treatment of Zr(IV) and Hf(IV) sulfate solution on the ion-exchange purifying of zirconium from hafnium on Diphonix® resin

The tendency of Zr(IV) and Hf(IV) to form polynuclear species (especially mixed Zr-O-Hf complexes) in aqueous solutions is, besides their almost identical chemical properties, one of the main obstacles in their separation. Therefore, finding a suitable way for the aforementioned complexes to decompose may play a crucial role in efficiently purifying zirconium from hafnium. The best purifying efficiency on Diphonix® resin was obtained with a zirconium sulfate solution prepared with the intermediate stage of fluoride complexes creation. This permits the collection of the purest fraction of the zirconium sulfate solution, which has a hafnium content ten times lower than in the case of typically prepared solutions.