Abstract:

In order to investigate the effect of crystal seeds and compound salt dopants on the phase transformation of TiO₂ crystal forms in calcination process of the titanium dioxide production by sulfuric acid method,the dehydration and desulfation in calcination process,changes of phase,composition of crystal form and granule morphology were analyzed by using the means of thermogravimetry differential thermal analysis（TG-DTA）,powder X-ray diffraction（XRD） and scanning electron microscopy（SEM）.Results showed that the metatitanic acid（MTA） experienced crystallization process from amorphous to anatase in order to transform to rutile crystal.It was found that calcined crystal seeds and salt dopants can effectively expand the temperature range of phase transformation from the range of 900~1 000 ℃ to the range of 850~1 050 ℃.The calcined crystal seeds promoted the phase transformation and reduced the starting point of phase transformation temperature by about 50 ℃.The salt dopants inhibited the size of crystal seeds at 800~900 ℃.After 900 ℃,the inhibition on the growth of crystal seeds was weakened.The phase transformation range was expanded and the crystal morphology was adjusted.It′s helpful in adjusting the crystal morphology,improving the particle size distribution and reducing the sinter ing degree.

Key words: TiO₂ calcining crystal seeds, salt dopants, phase transformation of TiO₂, granule morphology