Recovery of fluorides from gypsum
US4060586A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 15, 1976 |
| Grant date | Nov 29, 1977 |
| Priority date | — |
| Expiry date | Jun 15, 1996 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01B33/103
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
In a process for the reaction of phosphate rock and sulfuric acid in the presence of potassium ion to form a mixture of phosphoric acid and a precipitated gypsum wherein the presence of the potassium ion causes precipitation of fluorides from the phosphate rock as potassium silicofluoride as a coprecipitate with the gypsum, and the phosphoric acid is separated from the gypsum slurry, the potassium silicofluoride is separated from the gypsum by extraction with phosphoric acid which may contain from 0-25 weight percent of sulfuric acid based on the amount of gypsum to be extracted or such phosphoric acid which may contain some fluorine. This extraction procedure provides a substantially fluoride-free gypsum product and an extraction solution containing recoverable potassium silicofluoride.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.