Set the maximum microwave power at 700W, and continuously adjustable, microwave frequencies for 2.45GHz. Conditions as follows: microwave power 500W, APT 8g, calcination time interval for 1min. Known that weightlessness rate for ammonium paratungstate thermal decomposition is about 14.13%,then we can calculate the theoretical weight loss should be 1.13g in this experiment. The experiment results the weight loss of ammonium paratungstate was 1.08g, maximum weight loss rate was 13.50%, decomposition rate was about 95.58%, get yellow tungsten trioxide.

 

Three factors of orthogonal experiment were selected as bellows: microwave power (P), calcination time (T), material weight (W). Each factor selected from three levels, as shown in table 2:
                             

 

The orthogonal results are shown in table 3, as follow:
                             

 

Predictably in experiments of the microwave thermal decomposition of ammonium paratungstate preparation WO3, the best conditions of microwave calcination are: microwave power P=650W, calcining time=4min, material weight=10g.The rate of ammonium paratungstate decomposition reached highest, about 96.67%. However, at the same decomposition rate, 2 hours which is 30 times of microwave calcination will be taken in the traditional way . Visibly, microwave heating technology can speed up the secondary tungsten acid sodium preparation rate greatly, and its superiority is taken in a glance, make it a valuable approach to development in industry.

For microwave calcination preparation WO3 from ammonium paratungstate 1/2,please see in 
http://news.chinatungsten.com/en/tungsten-information/81906-ti-10605