Process for blending phosphoric acids of differing impurity content
AssigneeOccidental Chemical Corporation
InventorsHarold E. Mills, David L. Murdock, Richard M. Ramer, Francis M. Sale
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Abstract
Phosphoric acids of significantly different content of soluble impurities, especially magnesium compounds, can be blended to produce a phosphoric acid with a decreased tendency for forming detrimental solids when converted to a liquid fertilizer or on storage, or during transportation as when the acid is transported by ocean vessel or railroad tank car. The blending can be effected either before or after a concentration step or steps (e.g., evaporation to "merchant grade" or to superphosphoric acid). For example, wet process phosphoric acid produced by a dihydrate or gypsum process can be blended with a phosphoric acid produced by a hemihydrate process.
Claims21
Process for producing a blended phosphoric acid having an R-value no greater than about 0.86, where the R-value is one hundred times the ratio of the MgO analysis by weight divided by the P.sub.2 O.sub.5 analysis by weight of said acid, said process comprising blending a sufficient amount of at least one purified dihydrate process phosphoric acid having an R-value less than 0.86 with at least one phosphoric acid produced by a hemihydrate process and having an R-value greater than 0.86, to produce a blended phosphoric acid having an R-value no greater than about 0.86;
- wherein said purified phosphoric acid is purified by aging a dihydrate process phosphoric acid for sufficient time to allow at least some magnesium-containing solids to precipitate from said acid and separating at least some of said precipitated magnesium containing solids from said phosphoric acid by filtration to produce said purified dihydrate process phosphoric acid having an R-value less than 0.86.
Process for producing a blended phosphoric acid having an R-value no greater than about 0.86, where the R-value is one hundred times the ratio of the MgO analysis by weight divided by the P.sub.2 O.sub.5 analysis by weight of said acid, said process comprising blending a sufficient amount of at least one purified dihydrate process phosphoric acid having an R-value less than 0.86 with at least one phosphoric acid produced by a hemihydrate process and having an R-value greater than 0.86, to produce a blended phosphoric acid having an R-value no greater than about 0.86;
- wherein said purified phosphoric acid is purified by aging a dihydrate process phosphoric acid for sufficient time to allow at least some magnesium-containing solids to precipitate from said acid to produce a purified dihydrate process phosphoric acid having an R-value less than 0.86.
The process for producing a superphosphoric acid having a P.sub.2 O.sub.5 analysis of about 70% and an R-value no greater than about 0.86, where the R-value is one hundred times the ratio of the MgO analysis by weight divided by the P.sub.2 O.sub.5 analysis by weight of said acid, said process comprising:
- (a) blending a sufficient amount of at least one purified dihydrate process phosphoric acid containing about 48% P.sub.2 O.sub.5 and having an R-value less than about 0.6 with at least one phosphoric acid produced by a hemihydrate process which contains about 48% P.sub.2 O.sub.5 and has an R-value greater than 0.86, to produce a phosphoric acid blend having an R-value no greater than about 0.86;
- wherein said purified dihydrate process phosphoric acid is purified by treatment with a precipitant comprising calcium and fluoride followed by aging the purified dihydrate process phosphoric acid for sufficient time to allow at least some magnesium-containing solids to precipitate from said acid and separating at least some of said precipitated magnesium-containing solids from said phosphoric acid by filtration through a filter aid to produce said purified dihydrate process phosphoric acid having an R-value less than about 0.6;
- (b) concentrating said phosphoric acid blend in a first evaporation step to produce a phosphoric acid having a P.sub.2 O.sub.5 analysis of about 54% P.sub.2 O.sub.5 ;
- and
- (c) concentrating said phosphoric acid produced in step b in a second evaporation step to produce a superphosphoric acid having a P.sub.2 O.sub.5 analysis of about 70% P.sub.2 O.sub.5.
Dependencies are inferred from the claim text.