| Chemical Industry-Titanium dioxide |
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Titanium dioxide (TiO2)
Titanium dioxide is one of the most important pigments in the colour producing industry.
The production of TiO2 is a very good example of an advantageous application of chlorine.
Until 1960, the sulphate process, using sulphuric acid performed the digestion of titanium ores. Environmental problems with acidic waste waters led to the development of the chloride process, which is increasingly replacing the sulphate process.
In a fluidized bed rutile, an ore containing TiO2, reacts with chlorine at 750 - 1000 °C in the presence of cokes according to the reaction:
TiO2 + 2 Cl2 + 2C -> TiCl4 + 2CO
The gaseous TiCl4 is seperated from other metal chloride by fractionated condensation and purified by vaccum distillation. The pure TiCl4 is burned with air or oxygen to give pure TiO2 and chlorine gas
TiCl4 + O2 -> TiO2 + 2 Cl2
The chlorine gas is recycled into the chlorination process and the TiO2 further processed.
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