Flotation process for removal of precipitates from electrochemical chromate reduction unit
US3989608A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 30, 1975 |
| Grant date | Nov 2, 1976 |
| Priority date | — |
| Expiry date | Dec 30, 1995 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC02F2103/023
- WIPO fieldEnvironmental technology
- WIPO sectorChemistry
Abstract
This invention is an improved form of a conventional electrochemical process for removing hexavalent chromium or other metal-ion contaminants from cooling-tower blowdown water. In the conventional process, the contaminant is reduced and precipitated at an iron anode, thus forming a mixed precipitate of iron and chromium hydroxides, while hydrogen being evolved copiously at a cathode is vented from the electrochemical cell. In the conventional process, subsequent separation of the fine precipitate has proved to be difficult and inefficient. In accordance with this invention, the electrochemical operation is conducted in a novel manner permitting a much more efficient and less expensive precipitate-recovery operation. That is, the electrochemical operation is conducted under an evolved-hydrogen partial pressure exceeding atmospheric pressure. As a result, most of the evolved hydrogen is entrained as bubbles in the blowdown in the cell. The resulting hydrogen-rich blowdown is introduced to a vented chamber, where the entrained hydrogen combines with the precipitate to form a froth which can be separated by conventional techniques. In addition to the hydrogen, two materials present in …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.