Titanium dioxide finishing process

US7247200B2 · kind B2 · utility

Assignee

• E.I. DU PONT DE NEMOURS AND COMPANY · US

Inventors

• Russell Bertrum Diemer, Jr. · Hockessin, US
• Alan Roger Eaton · Hendersonville, US
• Narayanan Sankara Subramanian · Hockessin, US
• Stephen William Taylor · Chadds Ford, US
• George Schurr · Newark, US
• David A. Zimmerman · Wilmington, US

Key dates

• Filing date: Nov 1, 2005
• Grant date: Jul 24, 2007
• Expiry date: Nov 1, 2025

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/80
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

This disclosure relates to process for producing titanium dioxide (TiO2) pigments, comprising the following steps: a) oxidizing a mixture of titanium tetrahalide and a rutile forming agent, such as aluminum halide, present in the vapor phase and 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 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; d) separating the vapor phase to form a powder comprising the titanium dioxide particles and the scouring material; and e) simultaneously subjecting the powder to substantially uniform heating at a temperature of about 300° C. to about 600° C. and reducing the size of the titanium dioxide particles and the particles of the scouring material in the powder to a mean particle size of about 50 nm to about 1000 nm, whereby the titanium dioxide pigment has a chloride content of less than about 500 ppm. The so treated powder may have a residual free chlorine content of less than about 1 ppm.