2020年8月11日星期二

Microwave Ultrasonic Method for Customizing Ultrafine Ammonium Paratungstate

Ammonium paratungstate (APT) is the main raw material for the production of tungsten powder, tungsten carbide powder, tungsten wire and tungsten products.

microwave ultrasonic machine image

As everyone knows, the tungsten particle size, crystal morphology of its APT has a great "inherited" relationship, so, if want to produce nanometer tungsten powder and tungsten carbide powder, we first need to prepare ultrafine ammonium paratungstate (APT).

It is an innovative method to prepare superfine ammonium paratungstate (APT) by microwave ultrasonic combined crystallization. Many scholars have shown that compared with traditional heating crystallization, microwave ultrasonic combined crystallization has obvious advantages in speeding up the crystallization rate, refining the particle size and improving the purity of products. So what's the difference between microwave - ultrasonic combined crystallization and traditional evaporation crystallization?

Some scholars have used microwave-ultrasonic combined crystallization method for ultra-fine ammonium paratungstate (APT) preparation test, they used a certain volume of ammonium paratungstate solution placed in the use of XH-300A computer ultrasonic microwave combination synthesis extractor, set the ultrasonic frequency of 25 K Hz, adjust the microwave and ultrasonic power, in the specified value, using ultrasonic wave with microwave heating, at 45, 65, 80, 90, 95 degrees Celsius for evaporation crystallization, after a certain period of time, while the heat filter. After filtration, the filter material was washed with deionized water for 2 to 3 times, and the filtered material was dried in an electric constant temperature oven at 100 °C for 2 h to obtain ultrafine ammonium paramate powder.

The experiment concluded that in the absence of mechanical or magnetic stirring, adding surfactant, in the optimum preparation conditions of APT ultrasonic frequency of 25 K Hz, power 1000 W, microwave power 700 W, temperature 80 °C, ammonium tungstate concentration of WO3212 g/L, CO time 15 min, fine crystal APT-4 with average particle size of 7.6 m, uniform particle size distribution and crystal integrity can be obtained by microwave ultrasonic combined crystallization method.

Microwave ultrasonic assisted evaporation and crystallization can be prepared by micro APT in high temperature and without the addition of surfactant, can influence the crystallization rate and preparation of surfactants micro APT process APT purity to overcome the disadvantages of traditional heating. However, this method is only suitable for small scale production, more suitable for the special needs of the private custom, the main reason is the large microwave - ultrasonic equipment manufacturers almost did not come out, there are also expensive.

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