Preparation of monocalcium phosphate and phosphoric acid
US4160657A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 2, 1978 |
| Grant date | Jul 10, 1979 |
| Priority date | — |
| Expiry date | Aug 2, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S71/03
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
Monocalcium phosphate, phosphoric acid and/or potassium phosphate containing fertilizers are produced in a process involving acidulation of phosphate rock with phophoric acid in the presence of added silicon dioxide and potassium ion whereby fluorides contained in the rock are converted to K.sub.2 SiF.sub.6, wherein monocalcium phosphate dissolved in phosphoric acid is formed during acidulation. In an important feature, the K.sub.2 SiF.sub.6 is separated and hydrolyzed to regenerate the K.sub.2 O from K.sub.2 SiF.sub.6 as recycled KH.sub.2 PO.sub.4 /H.sub.3 PO.sub.4 solution for further reaction with fluoride from fresh phosphate rock feed. 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. In a closely related embodiment, the remaining MCP/H.sub.3 PO.sub.4 solution is reacted with sulfuric acid to produce phosphoric acid product and/or the recycle phosphoric acid required in the phosphate rock acidulation step.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.