Process for the reduction of the sodium hydroxide losses of the Bayer-type alumina production
US4486393A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 23, 1983 |
| Grant date | Dec 4, 1984 |
| Priority date | — |
| Expiry date | Feb 23, 2003 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01F7/066
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
The invention relates to a process for the reduction of sodium hydroxide losses of the Bayer-cycle by modified causticization of red mud which comprises PA0 subjecting an optionally previously concentrated red mud slurry led off from the red mud washing line by ramification and containing a liquid phase which has a concentration of 5-40 g. caustic Na.sub.2 0/1. caustification by adjusting the lime content expressed as CaO through addition of lime or lime milk to 1-3.2 moles per mole Al.sub.2 O.sub.3, preferably to 2-2.5 moles per mole Al.sub.2 O.sub.3, related to the total Al.sub.2 O.sub.3 content of the slurry; PA0 stirring the slurry for 0.3-5 hours at a temperature of 70.degree.-110.degree. C., preferably at 80.degree.-100.degree. C.; PA0 adding to the slurry 3-4 moles, preferably 3.2-3.4 moles, of soda related to 1 mole of the originally dissolved Al.sub.2 O.sub.3, and continuing the stirring for 1-4 hours at 80.degree.-100.degree. C., preferably at a temperature of 90.degree.-95.degree. C.; PA0 if necessary causticizing the excess of soda by adding lime or lime milk by methods known per se; PA0 if desired concentrating the slurry thus obtained and re-introducing the liquid pha…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.