Method for bleaching kaolin clay
US5753029A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 10, 1996 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | Dec 10, 2016 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/80
- WIPO fieldBasic materials chemistry
- WIPO sectorChemistry
Abstract
An improved method for improving the brightness of clay of the type that is capable of being bleached by an oxidative reagent, such as Georgia gray kaolin. Such clay, in the form of a dispersed slurry, is treated with a combination of an inorganic condensed phosphate, sodium hypochlorite and ozone, preferably including separate treatment steps of magnetic purification and reductive bleaching. Suitable phosphates include sodium hexametaphosphate, sodium tripolyphosphate and tetrasodium pyrophosphate. The hypochlorite is added shortly before ozonation, and the phosphate is added before, simultaneously with, or after the hypochlorite.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.