Production of Submicrometer-Sized Hexahydro-1,3,5-trinitro-1,3,5-triazine by Drowning-Out

Abstract

In the drowning-out crystallization of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) with a spray, effects of operating parameters such as spray distance, solute concentration, and antisolvent temperature on crystal size were investigated. It was found that there exists an optimum spraying distance of solution for the production of submicrometer-sized crystals: the crystal size decreases with increasing spray distance in the distance shorter than the optimum distance due to incomplete atomization and that increases with the spray distance at the distance longer than the optimum distance due to coalescence among fluttered droplets. Higher RDX concentration in starting solution induced larger product particles. However, too low RDX concentration was also found to be not preferred for the small-sized product since nucleation occurs after complete mixing of atomized solution droplets with the antisolvent. By similar reason, it was found that lower antisolvent temperature, which causes faster nucleation, is pr...