Production of titanium dioxide by sulfuric acid method--acid hydrolysis, leaching and reduction (4)

3. Avoid excessive reduction of tetravalent titanium In the production process of titanium dioxide, in order to inhibit the oxidation of divalent iron of titanium liquid into ferric iron, all the ferric iron must be reduced to divalent iron with iron filings or iron powder, and A small amount of tetravalent titanium is reduced to trivalent titanium. The reduction reaction is as follows:

Generally, the atmospheric pressure hydrolyzed titanium liquid is required to contain trivalent titanium 1-3 g/L, and the pressurized hydrolyzed titanium liquid contains trivalent titanium to be 2-5 g/L. Exceeding this amount is a reduction excess. According to the calculation, for each reduction of 2g / L, 1 ton of titanium dioxide will consume more sulfuric acid 16. 4kg, more waste of titanium dioxide 13. 4kg. The reason is that these more consumed sulfuric acid is an ineffective acid, these reduction of excess trivalent titanium It cannot be hydrolyzed to metatitanic acid precipitation during hydrolysis, but is discharged with waste acid. However, some manufacturers use a very low titanium liquid of trivalent titanium to prepare them before hydrolysis.
4. Avoid excessive oxidation. When the acid solution is cooled, the cooked hot material is cooled. It needs to be blown by the air of the drum. In order to accelerate the dissolution of the solid phase during the leaching, it is necessary to drum the air for stirring; When the iron powder is reduced, it is also necessary to drum the air for stirring until the stirring is stopped before discharging. The process of bubbling air is also the process of divalent iron in ferric oxide liquid in the air to trivalent iron or oxidation of trivalent titanium to tetravalent titanium. This oxidation process also requires the consumption of a certain amount of sulfuric acid. Its oxidation reaction formula is as follows:

According to the calculation of this oxidation reaction, the amount of sulfuric acid is 1.84 g, which is a non-acid. At the same time, the oxidized ferric iron is finally reduced to ferrous iron by iron filings or iron powder. This iron scrap reduction also requires acid consumption. It can be seen that excessive air blowing in the production process is harmful. Acid solution requires the addition of the same amount of sulfuric acid and the same amount of ilmenite per pot, and the final effective acid of each pot is different, and even some gaps are large. This is mainly because the amount of air per drum is different, and the amount of sulfuric acid consumed is not the same.

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