Appeal No. 1997-0844
Application No. 08/269,979
dihydrate cake (of gypsum) is washed with water to achieve a
final by-product (Answer, page 3). The examiner concludes
that it would have been obvious “to employ the [process] water
disclosed at column 4, lines 42-46 of Zibrida as the gypsum
wash water in the process of Davister et al because Davister
et al suggest that any suitable water may be used, and the pH
of the waste water effluent of Zibrida would be about 7.”
(Answer, page 3).
The examiner’s proposed combination of references is
flawed for two reasons. First, Davister does not suggest that
any water can be used as a wash water for the gypsum filter
cake but specifically teaches that “[t]he thus-formed calcium
sulphate cake in filter 30 is then subjected to washing with
hot water, as shown by arrow 41.” (col. 6, ll. 40-42). The
examiner has not shown by convincing evidence or reasoning
that the process water of Zibrida would have been considered
“hot water” sufficient to wash the filter cake of Davister.
Second, Zibrida teaches that the pH of the effluent of his
double neutralization process is only adjusted by addition of
acid “[i]f it is desired to discharge the effluent into the
environment ...” (Col. 4, ll. 42-46). Accordingly, if the
9
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Next
Last modified: November 3, 2007