Processing of ammonium paratungstate from tungsten ores
US4115513A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 16, 1977 |
| Grant date | Sep 19, 1978 |
| Priority date | — |
| Expiry date | Aug 16, 1997 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01G41/006
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
To obtain highly purified, lamp grade ammonium paratungstate crystals from any of several different tungsten ores, the ore is reduced to finely divided status and slurried in heated HCl solution to convert tungsten values to WO.sub.3.H.sub.2 O. Recovered tungstic oxide is washed and dissolved in heated aqueous solution of sodium carbonate or sodium hydroxide with the pH maintained at about 8 to 8.5 to form soluble sodium tungstate. Sodium hydroxide is added to raise the pH to about 10.5 to 11.5, and magnesium chloride is added in amount sufficient to somewhat neutralize the solution. Sodium hydroxide is added to raise the pH to about 10.5 to 11.5 to precipitate as hydroxide the magnesium and additional metallic impurities. At least one of ammonium sulfide and thioacetamide is and the heated solution is acidified to a pH in the range from about 2 to 3 to precipitate any molybdenum as MoS.sub.3. The tungstate solution is then contacted with an organic, water-immiscible ion exchange liquid in which the active ingredient is an amine salt to extract the tungsten values. Tungsten values are then stripped from the ion exchange liquid with ammonium hydroxide to form ammonium tungstate solu…
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