Tungsten Oxide Manufacturing Process
Tungsten oxide can be manufactured in several different ways. CaWO4, or scheelite, is allowed to react with HCl to produce tungstic acid, which decomposes to WO3 and water at high temperatures.
CaWO4 + 2 HCl → CaCl2 + H2WO4
H2WO4 + heat → H2O + WO3
Another common way to synthesize WO3 is by calcination of ammonium paratungstate (APT) under oxidizing conditions:
(NH4)10[H2W12O42]?4H2O → 12 WO3 + 10 NH3 + 11 H2O
Related Products:
Ammonium paratungstate (APT) is white crystalline powder, insoluble in water.
Ammonium metatungstate is white powder, soluble in water, solubility is 300g WO3/100ml H2O (in 25℃).
Sodium tungstate is an intermediate tungstate produced from tungsten concentrate, is the raw material for APT.