Controlled Hydrolysis of TiO₂ from HCl Digestion Liquors of Ilmenite

Traditionally, industrial scale production of the TiO2 pigment is achieved by hydrolysis from H2SO4 solution or TiCl4. However, route produces FeSO4 waste, which problematic, and TiCl4 requires a high grade rutile feedstock chemically upgraded ilmenite (FeTiO3). Here, we investigate direct to using aqueous HCl. New Zealand digested in 35 wt % HCl achieve containing typically 1.18 mol kg–1 Fe(aq)2+ 1.14 Ti(aq)4+ was hydrolyzed under reflux, after seed preparation water, with phosphoric citric acid. The structure determined Raman spectroscopy X-ray powder diffraction pair distribution function analysis, latter enabling identification short-range order poorly crystalline materials. hydrate precipitated either anatase structure. Unlike H2SO4, natural formed without use determining agents rutile. 0.4 H3PO4 per mole Ti (resulting 0.35 wt% hydrate) results formation. Sodium citrate acid addition also hydrate. mechanism for polymorph control may be kinetic rather than structural template surface adsorption. This process has potential used commercial pigment. Anatase advantage that traces iron more readily removed washing precipitate, making feasible material.