Minimal effluents discharge pulp mill with chemical recovery
US5549788A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 31, 1993 |
| Grant date | Aug 27, 1996 |
| Priority date | — |
| Expiry date | Aug 31, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S162/08
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
Effluents are minimized from a cellulose pulp mill having a recovery boiler by concentrating liquid effluents from the bleach plant and/or liquid spills from process streams, incinerating the concentrated effluents in the recovery boiler, removing particles present in the flue gases from the recovery boiler to produce an ash including salts containing potassium and chloride, and sulfur compounds, and removing the potassium and chloride from the ash while returning the sulfur containing compounds to the recovery loop, so as to balance the sulfur, chloride and potassium levels in the mill. The sulfur is typically returned directly to a stream of black liquor just before entry into the recovery boiler. Green liquor is produced from the melt, which preferably is treated to remove metals from it prior to caustization (e.g. by sedimentation and/or filtration), and prior to green liquor crystallization to produce sodium hydroxide.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.