Appeal No. 1998-2248
Application No. 08/552,407
titanium dioxide-rich fraction is returned to the chlorination
reactor.
In view of the claim construction supra, we determine that
the examiner’s findings from Paige do not establish a prima
facie case of obviousness. As recognized by the examiner,
Paige teaches recycle of a titanium dioxide-rich fraction from
the hydrocyclone that has been treated by gravity concentration
(i.e., tabling; see the Answer, page 6, and Paige, page 23,
left column). The examiner has failed to present any
convincing evidence or reasoning to support a conclusion that
it would have been obvious to recycle the untreated underflow
fraction from the hydrocyclone (i.e., Sample C). The
examiner’s position that omission of a step (i.e., gravity
concentration) with its attendant loss of function would have
been obvious is not supported by the teachings of Paige that
gravity concentration is essential to the recycle process. See
Paige, paragraph bridging pages 8-9, where it is taught that
Sample C (hydrocyclone waste) is subjected to gravity
concentration and a sizing step to remove silica gangue “since
all of the commercial producers expressed concern about the
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