The separation of hafnium from zirconium using tributyl phosphate offers interesting alternatives to present methods for making reactor-grade zirconium. Feed solution for the extraction step can be prepared from the reaction product of caustic and zircon sand. The purified zirconium can be converted into a variety of compounds, depending on the process chosen for reduction to the metal. It may be that future developments will show tributyl phosphate extraction to have advantages in new plants for the production of low-hafnium zirconium metal.
Cox, R. P. and Beyer, G. H., "Separation of hafnium from zirconium using tributyl phosphate" (1955). Ames Laboratory ISC Technical Reports. 109.