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US 4,391,784 AGranted
Foam control during production of phosphoric acid
OwnerRichard N. Hill, Sr., Charles D. B. Hillinventors
Life of this patent
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Abstract
Foam generated during the digestion of phosphate rock is removed from the slurry either by overflow, mechanical sweeps, or by vacuum from strategically located nozzles connected to vacuum lines. The foam, after liquefaction, is returned to the filter where it results in improved filtration and return of soluble P.sub.2 O.sub.5.
Claims5
In the production of phosphoric acid comprising the steps:
- (a) digesting ground phosphate rock with sulfuric acid and weak phosphoric acid recycled from Step (d) below to form a slurry comprising strong phosphoric acid and byproduct gypsum, and forming a foam on the surface of the slurry;
- (b) passing the slurry to a filtration operation;
- (c) separating gypsum from strong phosphoric acid in the said filtration operation thereby forming a gypsum filter cake of gypsum crystals;
- (d) washing the gypsum filter cake with wash water thereby forming weak phosphoric acid, and recycling said weak phosphoric acid to the digestion in Step (a);
- the improvement comprising
- (e) removing foam from the slurry surface;
- (f) liquifying the removed foam;
- and
- (g) passing the resultant liquid to the filtration operation;
- whereby the said gypsum crystals are caused to be better suited for filtration, and soluble P.sub.2 O.sub.5 is returned in the liquified foam.
7 more elements
Dependencies are inferred from the claim text.