Method for treating process water in connection with pulp bleaching
US6290812A · kind A · utility
2Cited by
2References
11Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Aug 31, 2000 |
| Grant date | Sep 18, 2001 |
| Priority date | — |
| Expiry date | Aug 31, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S210/928
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A method treats process water containing metal ions, in connection with bleaching of lignocellulosic pulp. The method is characterized by the steps of a) adjusting the Mg.sup.2+ content of the process water to form a flocculating base for metals and an organic substance; b) supplying a carbonate source to the process water to precipiate calcium as calcium carbonate; c) increasing the pH of the process water by adding white liquor to precipipate metals such as metal hydroxides; d) adding a flocculating agent to the process water; and e) separating the precipitated, flocculated metal compounds from the process water by flotation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.