Method for producing ammonium paratungstate
US4623534A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 21, 1985 |
| Grant date | Nov 18, 1986 |
| Priority date | — |
| Expiry date | Mar 21, 2005 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P10/20
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A method is disclosed for producing relatively pure ammonium paratungstate from an impure tungsten solution. The method involves first adding hexamethylenetetramine to the tungsten solution and adjusting the pH to from about 1.0 to about 2.0 with a mineral acid to form a first precipitate of a tungsten hexamethylenetetramine product, which is then separated from its mother liquor. The precipitate is then slurried in water and the pH adjusted to from about 7.0 to about 8.5 with ammonia to dissolve the precipitate. The resulting solution is then adjusted to from about 1.0 to about 2.0 with a mineral acid to form a second precipitate of the tungsten hexamethylenetetramine product which is then separated from its mother liquor. The second precipitate is then slurried in a solution of water and sufficient ammonia to form ammonium paratungstate which crystallizes out on evaporation of the slurry. The ammonium paratungstate is then separated from its mother liquor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.