1.School of Chemistry and Chemical Engineering， Beijing Institute of Technology， Beijing 102488， China;2.Qingyang Chemical Industry Corporation， Liaoyang 621000， China
It was proved that the sensitivity， safety and density of explosive compound were extremely affected by its morphology and particle size. The influence factor of hexanitrohexaazaisowurtzitane （CL-20） particle size was studied in the recrystallization process with the ultrasonic-assisted recrystallization method， the anti-solvent method and the optimization of agitator type， respectively . The effects of continuous and intermittent ultrasonic with different ultrasonic frequencies （20-40 kHz） were also investigated in order to obtain the small particle size product. In the recrystallization process with anti-solvent method， ethyl acetate and chloroform were applied as solvent and anti-solvent respectively. The dropping acceleration of chloroform （20， 50， 100 mL·h-1）， the ratio chloroform and ethyl acetate （1∶1， 1∶2， 1∶3）， the recrystallization time （24， 48， 72 h） and temperature （30， 40， 50 ℃） were optimized by orthogonal experiments. In addition， three types of agitator including four straight-blade open turbine， six straight-blade turbine and double-layer dispersing discs were performed in the CL-20 product morphology study together with their stirring speed effect. It was concluded that the assistance of intermittent ultrasonic could considerably reduce CL-20 crystal size. Particle size of 14 μm CL-20 could be obtained by ultrasonic assistant method while the frequency was controlled at 40 kHz with every 30 minutes vibration after 5 minutes stop. Moreover， L9（34）orthogonal experiments were designed and particle size of 140 μm CL-20 could be achieved when the crystallization time， temperature， the chloroform dropping rate， and the dropping amount was 72 h， 30 ℃， 20 mL·h-1 and 150 mL， respectively. Furthermore， three kinds of agitators were employed in the recrystallization process which obviously effected CL-20 morphology and particle size. A controllable particle size between 40-100 μm CL-20 crystals with spherical shape， a smooth and uniform surface were prepared with the double-layer dispersion disc. Comparing with the four straight blades open turbine type and the six straight blades turbine type agitator， it is proved that the product with desired impact sensitivity and friction sensitivity could be prepared by the double-layer dispersion disc method， which characteristic drop height and the explosion probability were 23.5 cm and 44%， respectively.
WANG Jia-lun, ZHANG Hong-bao, LIU Chun-zhu, et al. Production Process to Control Particle Size of Hexanitrohexaazaisowurtzitane[J]. Chinese Journal of Energetic Materials,2021,29(4):285-292.