Conversion of impure silver halide to ultra-pure silver metal
US6290747A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 8, 1999 |
| Grant date | Sep 18, 2001 |
| Priority date | — |
| Expiry date | Dec 8, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P10/20
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method for preparing ultra-pure silver from a crude silver halide matrix containing metallic and/or non-metallic impurities, said method comprising; PA1 roasting the crude silver halide matrix to substantially remove carbonaceous material; PA1 treating the roasted crude silver halide matrix with ammonium hydroxide to dissolve the silver halides and form an ammonium hydroxide reaction mixture; PA1 adding an initial reducing agent to the ammonium hydroxide reaction mixture to precipitate a crude silver powder mixture; PA1 separating the crude silver powder mixture from the ammonium hydroxide reaction mixture PA1 dissolving the crude silver powder mixture in nitric acid to form a crude silver nitrate solution; PA1 adding a first selective reducing agent to the crude silver nitrate solution to precipitate a silver/contaminant matrix and form a partially purified silver nitrate solution; PA1 separating the partially purified silver nitrate solution from the precipitated silver/contaminant matrix; PA1 adding a second selective reducing agent to the partially purified silver nitrate solution to precipitate pure silver powder; and PA1 isolating the pure silver powder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.