Waterless Granulation of Plastic Bonded Explosive (PBX) Pressing Powders via Resonant Acoustic Mixing (RAM)

摘要

Plastic‐bonded explosives (PBX) with low binder contents are commonly pressed to shape under highcompaction pressures to achieve higher density or lower porosity with higher performance than wouldnormally be achieved with melt‐cast or cast‐cure formulations. These PBX formulations have traditionallybeen formed into acceptably‐sized pressing powders using a water‐based slurry granulation process.During this process the solid constituents are agitated in a water bath and the binder is incrementallyadded to the slurry. As the carrier solvent is extracted the binder precipitates onto the solid particles,triggering granulation. During the course of this process a small quantity of nitramine is dissolved into thewater slurry, generating 6,000 to 7,000 liters of explosively contaminated water per batch, with 200 to400 batches being processed annually. This contaminated effluent must then be remediated beforedisposal, incurring significant cost to the Government.The development of a waterless granulation process would significantly reduce the fiscal andenvironmental cost associated with the manufacture of these pressing powders, particularly if theprocessing solvent used could be easily extracted and recovered for re‐use. The ideal manufacturingprocess would be completed remotely and would require no operator interaction between addition ofraw constituents and extraction of granules. Processes that minimize post‐process cleanup are alsoattractive.With these objectives in mind Rocky Mountain Scientific Laboratory (RMSL) has developed and optimizedprocedures for the laboratory‐scale manufacture of several PBX pressing powders using ResonantAcoustic Mixing (RAM). Through the use of novel processing techniques and fixtures RMSL has successfullydeveloped several waterless granulation processes that result in evenly sized spherical particles.Significant benefits of the developed processes include automated one‐pot mixing and granulation,efficient solvent recovery for re‐use, consistent granule composition, and mixing vessels that self‐cleanduring the granulation process.