Recovery of silver from photographic processor effluents
US4279644A · kind A · utility
7Cited by
7References
6Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 6, 1980 |
| Grant date | Jul 21, 1981 |
| Priority date | — |
| Expiry date | Jun 6, 2000 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P10/20
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Wash-off effluent from a photographic film processor is desilvered by a continuous process, employing the following sequence of steps: PA1 1. Addition of anti-foaming agent. PA1 2. Acidification. PA1 3. Chemical reduction of ionic silver to metallic silver by sodium borohydride in alkaline solution. PA1 4. Addition of one of more fluocculants. PA1 5. Passage through hold-up tank to allow time for flow formation. PA1 6. Filtration through automatic gravity filtration device or its equivalent. An apparatus for the treatment process is also provided.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.