Processes for the causticisation of Bayer liquors in an alumina refinery
US6676910B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 23, 2001 |
| Grant date | Jan 13, 2004 |
| Priority date | — |
| Expiry date | Mar 23, 2021 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01F7/473
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
An improved process for the causticisation of Bayer liquors in an alumina refinery includes a first step of reacting lime with aluminate ions in a Bayer liquor within a primary reactor operated at low to moderate temperature to form a hydrocalumite species and hydroxyl ions. In a second step, the hydrocalumite species is heated in contact with a Bayer liquor, which either includes or is a different liquor than the Bayer liquor of the first step, under controlled conditions to cause the hydrocalumite species to react with the liquor to form calcium carbonate, aluminate ions and hydroxyl ions. The principal advantages of the improved process include very high lime utilisation efficiencies (in excess of 90%) and a substantially increased C/S ratio (in excess of 0.955), allowing higher plant caustic concentrations and improved productivity. The loss of alumina due to the formation of unwanted calcium aluminate species is also greatly reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.