Abstract: A non-polluting liquid-phase process and a supporting system of apparatus for producing titanium dioxide from titanium ore or slag provide a more economical sulfate process for preparing anatase. The ore or slag is reacted with hot sulfuric acid. The reaction product is filtered and washed before being combined with acid water, in which the solids are partially dissolved. The resulting suspension is filtered, and the filtrate hydrolyzed to convert titanium values therein to titanium dioxide hydrate, which is calcined to produce anatase pigment.