Appeal No. 1996-1154
Application No. 08/174,497
1. A continuous process for manufacturing purified
silver nitrate solutions comprising the steps of:
a) transferring a crude silver nitrate solution,
together with a slurry comprising silver oxide, to a
multistage agitated reactor thereby forming a mixture;
b) maintaining a continuous weight percent undissolved
solids inside the reactor such that silver oxide is 10 to 80
weight percent of said undissolved solids;
c) transporting the mixture through the reactor over a
period over a period of 15 minutes to 3 hours to form a
reaction product;
d) filtering the reaction product through a continuous
filter to form a silver nitrate filtrate and a retentate; and
e) recycling the retentate to the reactor.
To maintain a continuous weight percent of undissolved
solids inside the reactor, “a differential density instrument
programmed in combination with a computerized signal processor
conventionally used to control chemical process” needs to be
employed. See specification, page 6, lines 17-21. “Two
density measurements are required because a single measurement
cannot distinguish between dissolved and undissolved solids.”
See specification, page 6, lines 28-30. The concentration of
undissolved solids is controlled by recycling a particular
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