Study on Preparation of Insensitive and Spherical High Bulk Density Nitroguanidine with Controllable Particle Size

Abstract

In this study, the solventing-out recrystallization method was applied to prepare insensitive and spherical high bulk density nitroguanidine (NQ). Experiments were performed at various operating conditions by using N-methyl-pyrrolidone (NMP) and acetone as solvent and antisolvent, respectively. The effects of different operating parameters such as NQ/NMP ratio, amount of acetone used, crystallization temperature, stirring speed and stirring time were investigated. The particle size and morphology of the prepared NQ crystals were observed by scanning electron microscopy (SEM), the bulk density was measured by the Archimedes' method and the impact sensitivity was determined by fall hammer method. The experimental results showed that the solventing-out recrystallization method could be used to prepare spherical high bulk density NQ with a narrow particle size distribution and the particle size could be controlled by changing the operating conditions. The bulk density of these spherical NQ particles was found to be in the range of 0.94-0.97 g cm-3, which is higher than that of needle-shaped NQ particles, and they became less sensitive towards impact.