Appeal No. 1997-0844
Application No. 08/269,979
APPENDIX
18. A nearly neutral non-scaling process water, useful in
wet-process phosphoric acid manufacturing also productive of
waste gases, waste gypsum solids as gypsum filter cake and
slurry, and liquid drainage therefrom, containing as
contaminants soluble fluorides, metal salts, and radioactive
compounds, at a pH of about 2; said process water being
produced by the following steps:
scrubbing some of said waste gases and combining the
resulting liquid with liquid drainage from the waste gypsum;
and
partially neutralizing and clarifying the combined
liquids to a pH of about 4.5, removing insoluble contaminants
in the underflow, then alkalizing and clarifying the clarified
liquid to a pH of about 11, removing more insoluble
contaminants in the underflow; and then
re-acidifying the resulting clarified decontaminated
liquid to a pH of about 6 to 7.
25. In wet-process manufacturing of phosphoric acid, the
improvement comprising using the process water of claim 18 in
washing said waste gypsum filter cake.
28. A composite process water useful in wet-process
phosphoric acid manufacturing also productive of phosphoric
acid leaks, spills, and wash liquids, also waste gases, waste
gypsum solids as gypsum filter cake and slurry, and liquid
drainage therefrom, containing as contaminants soluble
fluorides, metal salts, and radioactive compounds, at a pH of
about 2; comprising a mixture of the following:
(a) a continuously acidic process water produced by at
least one of the following steps: condensing some of said
waste gases, and mopping up leaks, spills, or wash liquids;
and
(b) a process water produced by the following steps:
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