Precipitation of aluminum oxide having low sodium oxide content
US4014985A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 1975 |
| Grant date | Mar 29, 1977 |
| Priority date | — |
| Expiry date | Dec 22, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01F7/144
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Aluminum oxide having a sodium oxide content after calcination of less than 0.1% by weight is continuously precipitated as aluminum hydroxide from a Bayer process liquor by a controlled slow precipitation. The controlled, slow precipitation rate required to create a low soda product is achieved by controlling the residence time of liquor in the precipitation vessel so as to provide a constant, low ratio of aluminum oxide to sodium oxide. Residence time control in a Bayer process plant is achieved by controlling green liquor flow rate to the tank, or by sizing the tank for a constant flow. The use of heavy seed charges to increase the seed surface area permits the production of a low soda product at a faster precipitation rate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.