Separation of trace molybdenum from tungstate solutions
US4303623A · kind A · utility
1Cited by
4References
27Claims
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Key dates
| Filing date | Jan 19, 1981 |
| Grant date | Dec 1, 1981 |
| Priority date | — |
| Expiry date | Jan 19, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22B34/36
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Dissolved molybdenum is removed from sodium tungstate solutions by adding sulfuric acid to lower the pH value of the solution to between about 8 and about 5, adding to the sodium tungstate solution a water-soluble sulfide in an amount of at least 0.5 gram per liter (gpl) in excess of that required to precipitate as sulfides molybdenum and certain other metals, then lowering the pH value of the sodium tungstate solution to between about 4.0 and about 1.5 as rapidly as possible with sulfuric acid in such a way as to precipitate molybdenum trisulfide while minimizing co-precipitation of tungsten.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.