Phosphoric acid crystallization process
US4655789A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 8, 1985 |
| Grant date | Apr 7, 1987 |
| Priority date | — |
| Expiry date | May 8, 2005 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/234
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The present invention discloses a new method for obtaining a crystallized phosphoric acid of relatively high purity starting with conventional phosphoric acid. The new method is based on crystallization of orthophosphoric acid hemihydrate from the phosphoric acid. Massive nucleation which would lead to the formation of unprocessable masses is avoided in the new method by providing unusually large amounts of fine relatively pure seed crystals of orthophosphoric acid hemihydrate and operating the crystallization process under conditions which favor crystal growth on the seed crystals and disfavor the occurrence of secondary nucleation. To prevent the crystallizing magma from reaching a viscosity which would render further processing difficult the present invention provides for recycling raffinate in an amount sufficient to maintain the solids content of the crystallizing magma below about 40%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.