| 摘要 |
<p>Titaniferous solid containing titanium (IV) oxide, for example ilmenite, is reacted with silicon tetrafluoride gas at 800°C or more and at a pressure of at least 1 atmosphere to produce titanium tetrafluoride vapour and silica. The vapour is rapidly removed from the reaction zone, preferably by rapid cooling to solid titanium tetrafluoride, at a sufficient distance from the reaction zone so as not to quench the reaction. The titanium tetrafluoride may be hydrolysed to produce titanium dioxide and hydrogen fluoride which is combined with silica to regenerate silicon tetrafluoride. It is preferred to pretreat the titaniferous solid by grinding and then roasting at 700°C to 750°C in air. Products of the reaction may be separated and purified by condensation and resublimation.</p> |
