Process for treating lignin
US9790641B2 · kind B2 · utility
Inventors
Key dates
| Filing date | Oct 13, 2015 |
| Grant date | Oct 17, 2017 |
| Priority date | — |
| Expiry date | Nov 17, 2035 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C9/02
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A process for recovery of lignin from black liquor that contains either soluble or dispersed lignin by generating a “liquid lignin” at high yield is disclosed. Soluble lignin at a high pH is precipitated by reducing the pH of the black liquor stream by countercurrent reaction with carbon dioxide, at elevated temperature and pressure, creating a dense liquid-lignin phase and a light lignin-depleted phase. The dense lignin-rich phase is separated and washed countercurrently with a non-sulfur containing acid, such as acetic acid or formic acid, to displace metal cations from the lignin, creating a low-salt lignin, which is then formed into a low-dust, high-bulk density lignin fuel pellet. If desired, an oxidation step may be used to eliminate odor for lignins having high value green chemistry applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.