The ultrasonic is a wave with a frequency higher than 20000Hz, always divided into ultrasonic power and ultrasonic detection in the practical application. Ultrasonic has a good direction, strong penetration ability, easy to obtain more concentrated energy, can also spread over a great distance in the solid and liquid with higher density. Because of the great genetic relationship in particle size, pattern and other physical properties between tungsten and ammonium paratungstate (APT), crystal structure of APT affects the pattern and properties of tungsten, to a great extent. Therefore, how to prepare high-quality APT products is becoming a key link in tungsten industry.
 

Introducing an ultrasonic field to ammonium paratungstate crystallization, observing the change of experiment. Conditions for the experiment set as follows: temperature for 80℃, ultrasonic frequency 170kHz. Experiment shows that ultrasonic can strengthen the APT crystal, also refined the crystal size of APT without obviously. So, how to refine crystal size while improving the crystallization rate of APT? 
 

If introduce microwave to acting on the crystallization process of APT with ultrasonic, how the result will be? We set the conditions as follows: the initial concentration of ammonium tungstate 265.66g/L, ultrasonic frequency 25kHz, a temperature of 95℃, ultrasonic power 1000W, microwave power 700W, crystallization time for 10min. We get an average particle crystal size of 5.2μm, the superfine micron crystal. And there is no need to add any surfactants or dispersants during the whole experiment which avoid to affect the purity of APT.