
Ammonium paratungstate powder (APT) may be produced by secondary reduction process. In other words, APT is reduced to blue tungsten oxide (BTO) in first stage, and BTO is reduced to tungsten powder (W powder) in the second stage. There are two methods for reducing APT to BTO – hydrogen reduction and self-reduction. And there are also two types of blue tungsten oxide – doped blue tungsten oxide and undoped blue tungsten oxide. The W powder using undoped blue tungsten oxide…