Process for production of pure tungstic acid or molybdic acid from impure alkali metal tungstate or molybdate solutions
US4975167A · kind A · utility
1Cited by
3References
2Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Sep 14, 1989 |
| Grant date | Dec 4, 1990 |
| Priority date | — |
| Expiry date | Sep 14, 2009 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01G41/00
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Acidification of impure alkali or ammonium tungstate or molybdate solutions prior to electrodialysis to produce tungstic acid or molybdic acid is carried out by the addition of pure tungstic acid or molybdic acid as the salts of tungsten isopolyacids or molybdenum isopolyacids, respectively. This is less expensive than using pure HCl or H.sub.2 SO.sub.4 and prevents contamination with chloride or sulfate ions. The pure tungstic acid or molybdic acid is isolated from the product.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.