Preparation and properties of ultrafine potassium picrate

To investigate the effect of particle sizes on properties of potassium picrate (KP), superfine potassium picrate was prepared by continuous spray addition, controlling speed dropping method and fast mixing method, respectively. The particle morphology, particle size distribution, thermal decomposition temperature, impact sensitivity, friction sensitivity, flame sensitivity, electrostatic spark sensitivity, 5 s delay explosion temperature and heat-wire sensitivity of potassium picrate with different size were measured. Results show that the values of mean particle size D₅₀ of potassium picrate obtained by continuous spray addition, controlling speed dropping method and fast mixing method are 3.9 μm, 8 μm and 16 μm, respectively. With the increase of potassium picrate particle size, the initial thermal decomposition temperature increases, the impact, friction, and flame sensitivity decrease, the electrostatic spark sensitivity is basically unchanged and 5 s delay explosion temperature decreases. Heat-wire sensitivity of superfine potassium picrate with D₅₀=3.9 μm is very low and it is suitable for used as low sensitivity current igniting composition.