Method for lignin separation from black liquor comprising removal of sulfur compounds from formed water effluent
US9475833B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 2011 |
| Grant date | Oct 25, 2016 |
| Priority date | — |
| Expiry date | Oct 17, 2031 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P40/40
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
The method is for separation of lignin from original black liquor (BLIN) having a first precipitation phase (PR1/PR2) for precipitation of lignin by a first acidification using acidifier, CO2, at alkaline conditions, then separating a lignin cake with subsequent suspension of the lignin cake in a strong acid to leach our metals from the lignin followed by dewatering and obtaining a clean lignin product LP. The acidic liquid phase (FL1) subjected to a sulphur removal process wherein a calcium containing compound is added to the acidic liquid phase, whereby sulphur in the acidic liquid phase is reacting with the calcium compound forming solid gypsum which could be separated and bled off from the process. The remaining acidic liquid could then be returned to the recovery process without negatively affecting the sulphur balance of the mill.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.