DMSO Recrystallization of HMX and RDX

Abstract : A pilot-scale process for recrystallization of RDX and HMX from DMSO was designed, procured, installed, and evaluated at Holston AAP. Process design was based on previous work which indicated cooling crystallization techniques using continuous nucleation and classified product removal to be most effective. Although all expected classes of material were successfully recrystallized, operating difficulties forced departure from the original equipment design and required implementation of alternate operating strategies. As a result, five distinct modes of operation were established, dependent upon the particular class of material being recrystallized. Two of these (for Class 5 RDX and Class 5 HMX) were batch. Although the pilot plant failed to demonstrate the design concept of a single, multiclass recrystallization process using separation and recombination to give desired class, the direct recrystallization techniques developed were satisfactory and, in some cases, could be scaled-up based on the data generated. In other cases more piloting will be required in order to develop the data base necessary for sound scale-up. Material recrystallized in the pilot plant was shown to meet all existing specifications. A variety of explosive formulations was produced for further testing which will include both interim qualification and end item tests. A preliminary economic analysis indicates DMSO to result in significant cost reduction for recrystallization of HMX at production rates in excess of 150,000 pounds per month, while little or no cost reduction is anticipated for RDX.