Influence of Cr Content in Ilmenite on Whiteness and Brightness of Titanium Pigments

Taking the two kinds of titanium white RA and RB produced by sulphate process in a domestic corporation as research targets,the influence of Cr content on whiteness and brightness of the crude titanium white pigments was studied. For the corresponding A (raw materials of RA) and B (raw materials of RB) ilmenite,the Cr distribution in the different working procedures and its influence on the qualities of titanium white pigments were deeply researched,and the mechanism was analyzed. Based on these results,there was also analysis on the reasons caused the differences of whiteness and brightness between RA and RB. It is indicated that both the whiteness and brightness of crude titanium white pigments decrease with increasing Cr content,and the tendency becomes sharp when the Cr content exceeds 20 ×10^-6. The more Cr in ilmenite,the higher Cr content in titanyl sulfate solution,and the residue content of Cr in meta- titanic acid keeps the same with that in crude titanium white. Furthermore,with a high content of Cr in titanyl sulfate solution,it is easy for the doping of Cr into the lattice of meta- titanic acid which affects the whiteness and brightness of crude titanium white pigments.