Electromembrane processes for the treatment of kraft mill electrostatic precipitator catch
US5567293A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 22, 1994 |
| Grant date | Oct 22, 1996 |
| Priority date | — |
| Expiry date | Dec 22, 2014 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21C11/066
- WIPO fieldChemical engineering
- WIPO sectorChemistry
Abstract
A process for the recovery of alkali metal hydroxide and acid from the alkali metal salts of monovalent anions which are mixed with the alkali metal salts of multivalent anions employs a water-splitting system composed of bipolar membranes in conjunction with ion-selective membranes; a two-compartment cell employs monovalent anion-selective membranes to define salt/base and acid compartments with the bipolar membranes, and a three-compartment cell employs, monovalent anion-selective and cation-selective membranes to define with the bipolar membranes, acid, salt and base compartments; the process has particular applicability to the conversion of the sodium/potassium chloride portion of the Electrostatic Precipitator (ESP) Catch of the recovery boiler of coastal and/or closed-cycle kraft pulp mills, a mixture of mostly sodium/potassium sulphate and chloride, into sodium/potassium hydroxide and hydrochloric acid; the remaining sodium/potassium sulphate solution, depleted in chloride, can thus be used as sodium/sulphur make-up to the recovery cycle or converted to sulphuric acid and sodium/potassium hydroxide; a simpler version of the process, can be employed for the electrodialytic se…
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