Separation of sulphides from pulping liquors by electrodialysis
US5536384A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 14, 1995 |
| Grant date | Jul 16, 1996 |
| Priority date | — |
| Expiry date | Feb 14, 2015 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC02F2201/46115
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A process using an electrodialysis system employing cation-selective membranes and anion-selective membranes, particularly monovalent anion-selective membranes is used to separate kraft pulping liquors into two streams; one that is rich in sulphides (to be used in the initial stage of pulping), and another that is poor in sulphides (to be used in the final stage of pulping). By separating pulping liquors in this way, the sulphur balance in the kraft process can be maintained while obtaining the benefits of modified pulping. The same electrodialytic system can be used to separate green and polysulphide liquors into sulphide-rich and sulphide-poor components.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.