Tungstic Acid

Tungstic acid is an important chemical product of tungsten, it has wide application, chemical formula is mWO3·nH2O. Tungstic acid is poly chemical compound of combination with WO3 and water by different ratio, the common seen tungstic acid includes yellow tungstic acid, white tungstic acid and metatungstate.

Yellow tungstic acid is yellow crystalline, insoluble in water, sulfur acid and nitride acid, slightly soluble in hydro chloride. When calcinating above 500℃, it will dehydrate and become tungsten trioxide. White tungstic acid is light yellow or white powder, density is 4.613, soluble in water, its solution is acidity and unstable, easy to turn into yellow tungstic acid, and can easily become glue state. Metatungstate is poly tungstic acid, it is the only confirmed compound of many tungstic acid structure, it is colorless crystalline, soluble in water, stable under 150℃.

Ion exchange method and solvent extraction method are main producing methods for tungstic acid. Ammonium paratungstate reacts with hydro chloride can obtain tungstic acid. Besides that, ammonium paratungstate has higher purity, so obtained tungstic acid also has higher purity.

In early times, tungstic acid is important intermediate compound in tungsten wet metallurgy. It is now replaced by APT. Tungstic acid is still the main raw material of sub-micron tungsten powder and tungstate, also used for mordant of textile, smoke suppressor of poly vinyl chloride, glazing agent and catalyst for high-grade petrol.

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