Titanium dioxide (TiO2) were most widely used Ti products, which can be used as coatings, fillers for plastic and paper, adsorbents, cosmetics, catalysts and gas sensors. The commercial technologies for the production of pigment grade TiO2 include sulfate process and chloride process which either resulted in serious
Researchers with the Institute of Process Engineering (IPE) proposed an anti-caking method for the decomposition of low-grade titanium slag in the NaOH system. This is an improvement compared with the novel metallurgical process which was recently developed by IPE. The new method, which involves the two-step reaction of low-grade titanium slag with molten NaOH without the introduction of additives, can significantly reduce the extent of caking.
In their experiments,a mixture of NaOH and low-grade titanium slag was first reacted at 350 °C for 60 min. The temperature was then increased to 550 °C in 40 min. Finally, the mixture reacted at 550 °C for 75 min.The extent of caking of the intermediate product obtained through the two-step molten salt reaction was significantly reduced.
A NaOH-to-slag mass ratio of 1.2:1 should be used to ensure a high conversion ratio in the process. The Brunauer–Emmett–Teller (BET) surface area and apparent density were used to characterize the extent of caking.
The chemical analysis showed that in the process of two-step molten salt reaction, the silicate phase prior pseudobrookite phase to react with molten NaOH at 350 °C in the process of two-step molten reaction. Microstructural and Fourier transform infrared (FT-IR) absorption results showed that the firstly formed sodium silicate did not diffuse into the entire reaction system and powder-shaped intermediate product was formed. Approximately 97% of titanium in the titanium slag could be extracted under the optimal reaction conditions.
In addition, the purity of the TiO2 obtained in the product is up to 99.3 wt.%. The greatest advantage of the proposed method is no introduction of other additives. Hence, purification is not required in the follow-up process.
The paper was published in Power Technology.
