Method for separating lignin from black liquor
US8486224B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 8, 2005 |
| Grant date | Jul 16, 2013 |
| Priority date | — |
| Expiry date | Oct 6, 2029 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P40/40
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Method for separating lignin from black liquor includes the following steps: a) precipitating lignin by acidifying black liquor and thereupon dewatering, b) suspending the lignin filter cake obtained in step a) to obtain a second lignin suspension and adjusting the pH level to approximately that of the washing water of step d) below, c) dewatering of the second lignin suspension, d) adding washing water and performing a displacement washing at substantially constant conditions without any dramatic gradients in the pH, and e) dewatering the lignin cake produced in step d) into a high dryness and displacing the remaining washing liquid in the filter cake, whereby a lignin product is obtained which has an even higher dryness after the displacement washing of step d). The lignin product or an intermediate lignin product obtained by the method, and its use, preferably for the production of heat or chemicals is also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.