Appeal No. 95-2245
Application No. 08,011,563
An example of a manufacturing process which produces
sulfur as a by-product is the preparation of
titanium dioxide pigments via vapor phase oxidation
of titanium tetrachloride (the so-called chloride
process). In this process titanium-containing ores
or slags are chlorinated in a reducing atmosphere in
a reactor at about 1000 C. Carbonaceous materials,o
such as petrol coke are used as a reducing agent.
The gas mixture leaving the reactor contains besides
the metal chlorides (particularly titanium
tetrachloride and various metal chlorides), coke,
unreacted ore, silicon dioxide, carbon dioxide,
carbon monoxide, nitrogen, hydrogen chloride and,
because of the sulfur content of the coke, carbonyl
sulfide. After further treatment, the exhaust gas
is burned before introduction into the atmosphere
because of its carbon monoxide content; in this
burning, carbonyl sulfide is converted into sulfur
dioxide and carbon dioxide. The sulfur compounds
must be removed from the exhaust gases under
existing regulations.
This chloride process is admittedly known. See Specification,
page 1.
In rejecting claim 1, the broadest claim on appeal, the
examiner relies only on the Quemere reference. According to
the examiner (Answer, page 4), “the Quemere reference
discloses ... hydrolysis of carbonyl sulfide in a gas mixture
using titanium dioxide particles.” The examiner then
concludes (Answer, page 5) that:
it would have been obvious to one of ordinary skill
in the art at the time the invention was made to use
any available source of titanium dioxide in
10
Page: Previous 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Next
Last modified: November 3, 2007