Why must ilmenite be upgraded before it can be used in carbo-chlorination?

Ilmenite must be upgraded before it can be used in the carbo-chlorination process because current environmental and economic constraints require the ore feedstock to contain more than 90 percent titanium dioxide (TiO₂).1

While natural rutile already meets this high-purity requirement, raw ilmenite does not. To bridge this gap, ilmenite is processed through a combination of pyrometallurgical and hydrometallurgical techniques to create a synthetic rutile that reaches the necessary 90 to 93 percent TiO₂ concentration. This upgrading ensures the feedstock is suitable for the chlorination process, which converts titanium oxides into titanium tetrachloride (TiCl₄).1