Method for the preparation of fibrous insoluble calcium sulfate anhydrite
US4029512A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 5, 1974 |
| Grant date | Jun 14, 1977 |
| Priority date | — |
| Expiry date | Aug 5, 1994 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2004/61
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A process is described for the formation of fibrous insoluble calcium sulfate anhydrite, the fibers thereof having specified dimensions. A dilute aqueous suspension of gypsum and, if desired, a crystal habit modifier suitable for the formation of fibrous calcium sulfate hemihydrate, is first formed. The gypsum in this suspension is then converted to the fibrous hemihydrate by reaction in the presence of saturated steam at 120.degree. C to 155.degree. C for 0.5 to 2.5 hours, thereby forming fibrous calcium sulfate hemihydrate of the desired dimensions. The fibrous hemihydrate is thereafter calcined at 500.degree. C to 750.degree. C for 0.5 to 3.0 hours to convert the fibrous hemihydrate to fibrous insoluble calcium sulfate anhydrite having substantially the same crystalline shape and dimensions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.