Niobium, Tantalum, and Titanium Fluoride Solutions

Parameters for the preparation of concentrated tantalum, niobium, and titanium fluoride solutions by dissolution of their oxides or hydroxides in hydrofluoric acid were studied. Anatase titania, niobium oxide, and tantalum oxide calcined to 900°C were found to have high dissolution rates. Solid phases separated upon the dissolution of niobium, tantalum, and titanium oxides in hydrofluoric acid were identified as NbO2F, TaO2F, Ta3O7F, and TiOF2. Niobium hydroxide dissolution in an autoclave at the atmospheric pressure gave various complex salts: NH4NbOF4 and (NH4)3Nb2OF11.