Membrane processes for treatment of and recovery of components from kraft black liquors
US4775480A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 29, 1987 |
| Grant date | Oct 4, 1988 |
| Priority date | — |
| Expiry date | Jan 29, 2007 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02W30/84
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A process for the treatment of an aqueous stream containing an acid or base and typically a precipitatable material such as a metal ion comprises: PA1 (a) subjecting the aqueous stream to (i) a treatment to produce a relatively pure stream of water and a concentrated aqueous stream, and (ii) water splitting to produce a stream of base, a stream of acid and a dilute aqueous stream of a concentration lower than the concentrated aqueous stream, the treatments (i) and (ii) being effected in either order, PA1 (b) recycling at least part of the pure water stream produced in (a) (i) to an earlier stream either in the production leading to said aqueous stream or to step (i) or (ii), PA1 (c) recycling at least part of the acid and/or base streams produced in (a) (ii) to an earlier stream either in the production leading to said aqueous stream or to an earlier step in the process, and PA1 (d) recycling at least part of the lower concentration stream produced in (a) (ii) to either (a) (i) or to another step in the process, whereby, when present, only the precipitatable material is removed from the aqueous stream, thereby obviating toxic waste disposal problems.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.