Process for extracting pure, coarse grain silicic acid crystals from spent lye
US5730838A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 21, 1996 |
| Grant date | Mar 24, 1998 |
| Priority date | — |
| Expiry date | Jun 21, 2016 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C11/106
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A process is disclosed for extracting pure, coarse-grain silicic acid crystals from silicic acid-containing spent lye in cellulose production, comprising adding coarse-grain silicic acid to alkalized spent lye, lowering the pH of the alkalized spent lye to about 9 such that a sediment is formed, separating the sediment formed into coarse grain and fine grain silicic acid with little lignin and lignin-containing spent lye free from silicic acid, and separating the coarse grain and fine grain silicic acid with little lignin into course grain silicic acid and lignin. At least part of the course grain silicic acid separated is fed back to the alkalinized spent lye to be desilicified.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.