Blue tungsten oxide preparation contains two methods: wet separation and fire separation. The raw materials are ammonium paratungstate, tungsten trioxide and sodium tungstate.
Fire method is a general method for industry. In general, ammonium paratungstate (APT) is the raw material, which is prepared by the thermal decomposition or the hydrogen reduction. Blue tungsten oxide can be obtained by the mild hydrogen reduction of WO3, but the quality is not as good as that of blue tungsten oxide prepared by using APT as raw material.
Wet method is newly developed in recent years. The ammonium hydroxide solution can product 3.5 (NH4) 2O•5WO2•13WO3•4.5H2O blue tungsten oxide. The reduction of blue tungsten oxide from tungsten solvent extraction organic phase can be prepared by hydrogen O:W=2.82.
The production equipment of blue tungsten oxide is as follows :