Propellants Explosives Pyrotechnics, Vol.46, No.5, 766-781, 2021
Thermo-Kinetic Investigation of the Preparation of Micronized Ammonium Perchlorate Particles by Using Rapid Cooling Crystallization Method
Production of micronized ammonium perchlorate particles (AP) (<25 mu m) has a great importance in the composite solid propellant industry. In the present study, an attempt was made to consider thermo-kinetic preparation of AP particles by using simple McCabe model in a cooling crystallization system. For this reason, an experimental design based on temperature, pressure, time, and concentration was used. Temperature in the range of 323-343 K, pressure in the range of 3x105 -18x105 Pa, and concentration in the range of 0.4-0.5 g/mL were set for the experiments. The time parameter was variable regarding to the temperature and concentration of each experiment and it was measured to evaluate the rate of process. The crystal size as an experiment response was estimated using image analysis of produced samples by MIP software in micrometer scale. Finally, a growth rate equation was established considering the results obtained from temperature variations, pressure, concentration, and time. Decrease in temperature variations caused to increase in crystallization rate and crystal size. The pressure above 7.5x105 Pa resulted in producing crystals smaller than 40 mu m. The lowest crystal size was observed in the concentration of 0.45-0.5 g/mL and the crystallization time below 8 s. In addition, the results obtained from presented equation and experiment were matched with McCabe model.