Recovery of P.sub.2 O.sub.5 values from phosphoric acid hemihydrate crystals
US4853201A · kind A · utility
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20Claims
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Key dates
| Filing date | Jul 11, 1988 |
| Grant date | Aug 1, 1989 |
| Priority date | — |
| Expiry date | Jul 11, 2008 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/2295
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
P.sub.2 O.sub.5 values occluded in the crystals which are precipitated during the hemihydrate process for manufacturing phosphoric acid are recovered by dissolving and recrystallizing the hemihydrate crystals as dihydrate crystals in an acidic environment having a P.sub.2 O.sub.5 concentration of from about 0.1% to about 10% and a free sulfate concentration in the range of about 0.1% to about 10%. Water is used to wash the dihydrate filter cake, and the filtrate from this wash is used to redissolve the hemihydrate crystals. The free sulfate values are preferably supplied to the dihydrate crystallizer as sulfuric acid.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.