Process for producing high purity phosphates
US7374740B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 31, 2005 |
| Grant date | May 20, 2008 |
| Priority date | — |
| Expiry date | Dec 29, 2025 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/30
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Phosphate rock is reacted with phosphoric acid to produce monobasic calcium phosphate. Monobasic calcium phosphate is reacted with ammonium carbonate to produce ammonium phosphate. Dibasic calcium phosphate is also produced as a by-product when monobasic calcium phosphate reacting with ammonium carbonate. The dibasic calcium phosphate is reacted with sulfuric acid to produce phosphoric acid. The phosphoric acid is used to react with phosphate rock. Ammonium sulfate or ammonium hydroxide may be used instead of ammonium carbonate. Phosphate other than ammonium phosphate can be produced if calcium phosphate is reacted with x-y to produce x-phosphate, where x is lithium, sodium, ammonium or potassium and y is carbonate, bicarbonate hydroxide or sulfate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.