Method of recovering sodium hydroxide from sulfur free pulping or bleaching waste liquor by mixing ferric oxide with condensed waste liquor prior to burning
US4000264A · kind A · utility
12Cited by
7References
4Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 1, 1974 |
| Grant date | Dec 28, 1976 |
| Priority date | — |
| Expiry date | Oct 1, 1994 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P40/40
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
This invention relates to a new and improved recovery method of chemicals from waste liquor of pulping or bleaching. More particularly, this invention relates to a method for direct recovery of sodium hydroxide from waste liquor of pulping or bleaching which is substantially free from sulfur compounds. Ferric oxide is admixed with concentrated waste liquor and thereafter the admixture is burned to form a smelt. By submerging the smelt in hot water a solution of sodium hydroxide and a ferric oxide precipitate are obtained. The precipitated ferric oxide can be reused in the mixing step.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.