A thermogravimetric study of the fluorination of zirconium and hafnium oxides with anhydrous hydrogen fluoride gas

Zircon mineral contains about 1–3% hafnium which is an undesirable impurity in the nuclear industry. A novel dry fluorination route was investigated to produce ZrF4 as a possible intermediate for the production of nuclear grade zirconium metal. The process was investigated by the reaction of pure ZrO2 and HfO2 with anhydrous hydrogen fluoride using a thermogravimetric analyzer. The findings indicate successful formation of ZrF4, HfF4, and oxyfluorides identified with X-ray powder diffraction. According to the TGA experiments, the stoichiometric formation of ZrF4 was realized at 525 °C whilst that for HfF4 was not attained.