Process for producing wet process phosphoric acid from phosphate rocks containing fluochlorapatite and related minerals
US4485078A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 1983 |
| Grant date | Nov 27, 1984 |
| Priority date | — |
| Expiry date | Mar 8, 2003 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B25/238
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Phosphoric acid is produced by the wet process from phosphate rock containing fluochlorapatite. The rock is ground in a crusher (10) to a size such that from about 50% to about 90% by weight will be passed by a -200 mesh U.S.S. sieve before being passed into a digestor (14) where it is mixed with sulfuric acid and recycled phosphoric acid to form a slurry. A suitable reductant such as sulphur dioxide is added to the slurry to maintain the oxidation-reduction potential in the range from about +150 mv to about +750 mv. The gypsum by-products are then removed from the slurry at filter (16) and a portion of the acid is recycled to digestor (14). The remaining acid is either concentrated and further processed to make fertilizers or is further processed via path (20) to remove aluminum and/or iron impurities. Select amounts of fluoride and sodium containing compounds are added to the acid in a stirred reactor (30) to cause precipitation of aluminum, principally as Na.sub.2 AlF.sub.5. After about 15 to about 60 minutes of stirring at a temperature below about 70.degree. C., the precipitate is removed at filter (32) where the acid is either processed to make fertilizer or subjected to addi…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.