Caustic solution having controlled dissolved aluminum content
US4136026A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 23, 1977 |
| Grant date | Jan 23, 1979 |
| Priority date | — |
| Expiry date | Nov 23, 1997 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC23F1/36
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A method of controlling the dissolved aluminum content of a caustic solution for etching aluminum comprises providing a tank of an etching solution containing sodium hydroxide and water and etching aluminum in the solution to dissolve aluminum therein. A portion of this etch solution is introduced to a reactor for purposes of lowering its aluminum content by treating with aluminum hydroxide. The treatment is capable of causing dissolved aluminum to precipitate from the etch solution in a mean residence time of less than 5 hours. A portion of the solution in the reactor is filtered to remove aluminum hydroxide solids to an extent sufficient to prevent precipitation in the etching tank. The filtered solution is then returned to the etching tank thereby controlling the aluminum content of the etching solution.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.