Preparation of monocalcium phosphate and/or phosphoric acid from phosphate rock
US4435370A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 29, 1981 |
| Grant date | Mar 6, 1984 |
| Priority date | — |
| Expiry date | Sep 29, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC05B7/00
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Monocalcium phosphate, phosphoric acid and/or potassium phosphate, calcium fluoride and gypsum are produced in a process involving acidulation of phosphate rock with phosphoric acid, and wherein monocalcium phosphate dissolved in phosphoric acid is formed during acidulation. In important features, insolubles and impurities are removed and a portion of the monocalcium phosphate may be separated and recovered. Alkali metal ion is added to the solution to form alkali metal fluosilicate, such as K.sub.2 SiF.sub.6, is separated and hydrolyzed with calcium ion to form CaF.sub.2 and the solution is recycled as RH.sub.2 PO.sub.4 /H.sub.3 PO.sub.4 for further reaction with fluorides, where R is alkali metal. A portion of the MCP/H.sub.3 PO.sub.4 solution and/or crystallized monocalcium phosphate can then be reacted with potassium sulfate, potassium bisulfate, or mixtures thereof, to form KH.sub.2 PO.sub.4 or KH.sub.2 PO.sub.4 /H.sub.3 PO.sub.4 solutions, and gypsum or with H.sub.2 SO.sub.4 to produce phosphoric acid. The remaining monocalcium phosphate/phosphoric acid solution can be reacted with sulfuric acid to produce phosphoric acid product and the recycle phosphoric acid required in th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.