Appeal No. 96-3499 Page 2
Application 08/271,569
The appellants' invention relates to a method of recovery
of tungsten from spent catalysts. An understanding of the
invention can be derived from a reading of exemplary claim 1,
which is reproduced below.
1. A method for recovering tungsten from a composition
consisting essentially of a tungsten containing spent
catalyst, said method comprising:
a) digesting said catalyst in aqueous sodium hydroxide
solution wherein the mole ratio of said sodium hydroxide to
said tungsten contained in said spent catalyst is from about
2.6 to about 4.2 and wherein the amount of water is sufficient
to dissolve the subsequently produced sodium tungstate, at
atmospheric pressure and a temperature of about 90EC for a
length of time of at least about 1 hour to convert greater
than about 77% by weight of said tungsten contained in said
spent catalyst to sodium tungstate and form a sodium tungstate
solution thereof and a residue containing the balance of the
starting tungsten; and
b) separating said sodium tungstate solution from said
residue.
The sole reference of record relied upon by the examiner
in
rejecting the appealed claims is:
Wiewiorowski 4,666,685 May 19, 1987
Claims 1 through 4 stand rejected under 35 U.S.C. § 103
as being unpatentable over Wiewiorowski.
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