Method of recovering pulping chemicals from dissolved ash having a high carbonate content
US9574303B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 26, 2016 |
| Grant date | Feb 21, 2017 |
| Priority date | — |
| Expiry date | May 26, 2036 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P40/40
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A method of recovering wood pulping chemicals from black liquor produced in a wood pulping process where the process entails burning the black liquor in a recovery boiler to form ash containing high levels of carbonate as well as sodium, potassium and chloride. The ash is dissolved to form a dissolved ash solution that is directed to a first stage crystallization unit that concentrates the dissolved ash solution and which results in the precipitation of sodium sulfate and sodium carbonate. Thereafter the concentrated dissolved ash solution is directed to a second stage crystallization unit which adiabatically cools the concentrated dissolved ash solution to form a glaserite slurry and a purge stream that is rich in chloride. In order to reduce the tendency of sodium carbonate and burkeite to crystallize in the second stage crystallization unit and to encourage pure glaserite to crystalize in the crystallizer, the method entails mixing a sulfate source, such as sodium sulfate or sulfuric acid, to the concentrated dissolved ash solution upstream of the crystallizer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.