Process for reducing the amount of halogenated organic compounds in spent liquor from a peroxide-halogen bleaching sequence
US5143580A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 1991 |
| Grant date | Sep 1, 1992 |
| Priority date | — |
| Expiry date | Apr 23, 2011 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C9/163
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A process for delignification and bleaching of chemically digested lignocellulose-containing pulp for reduced formation and discharge of halogenated organic compounds, while preserving the pulp quality, where the prebleaching with halogen-containing bleaching agent is replaced by a treatment, in a first step, with the addition of a complexing agent at elevated temperature and at a pH from 3.1 to 9.0, and in a second step, by using a peroxide-containing compound under alkaline conditions, whereupon spent liquor from the final bleaching with halogen-containing compounds is recycled to the first or second step of the halogen-free prebleaching.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.