Patent ID: 7247200

Claim:
A process for producing titanium dioxide pigment, comprising the following steps: a) vapor-phase oxidizing a mixture of titanium tetrahalide and a rutile forming agent in the presence of a nucleant to form a gaseous suspension comprising titanium dioxide particles; b) passing the gaseous suspension to a cooling conduit; c) introducing scouring material particles into the cooling conduit, wherein the particles of the scouring material have a diameter in the range of about 0.25 mm to about 12.7 mm and forming a cooled product having a solid and a vapor phase; d) separating the vapor phase from the cooled product to form a powder comprising the titanium dioxide particles and the scouring material; and e) subjecting the powder to substantially uniform heating at a temperature of about 300° C. to about 600° C. while size reducing at least the titanium dioxide particles of the powder to form titanium dioxide particles having a mean particle size of about 50 nm to about 1000 nm.