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US 5,158,594 AGranted
Granulated nitrogen-phosphorus-potassium-sulfur fertilizer from waste gypsum slurry
OwnerRonald E. Oxfordinventor
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Abstract
Process for converting phospho-gypsum waste product from the wet process of manufacturing phosphoric acid from phosphate rock by ammoniating said product at a pH of 6.5 or less and adjusting the phosphorus and potassium values of said ammoniated product by addition of one or more sources of potassium and phosphorus.
Claims13
A process for converting phospho-gypsum waste by-product, produced in the manufacture of phosphoric acid by the wet-acid process in which phosphate rock is treated with sulfuric acid to produce said phospho-gypsum waste product, into a granulated fertilizer, said process comprising the steps of:
- (a) forming an aqueous slurry comprising said phosphogypsym waste product;
- (b) ammoniating said phospho-gypsum waste product;
- (c) adding at-least one source of phosphorus and potassium in an amount sufficient to adjust nitrogen-phosphorus-sulfur potassium values of said ammoniated product and to form an adjusted slurry, so that the final product will be useful as a granular fertilizer;
- and
- (d) adjusting pH of said adjusted-slurry to a pH up to about pH 7.
2 more elements
Dependencies are inferred from the claim text.