Automated propellant blending

Apparatus for manufacturing a solid propellant mixture of oxidant and fuel particles in a binder, comprising:

• a mixing container;
• a variable-speed impeller for agitating a mixture of binder, solvent and solid particles in the mixing container;
• a countersolvent supply system for adding countersolvent to the mixing container;
• a decanting line for removing supernatant liquid from the mixing container;
• a control system for adjusting the speed of the impeller, adjusting the rate of countersolvent addition and actuating liquid removal from the mixing container, said control system including:
• (a) a countersolvent metering routine for effecting the steps of (1) adding the countersolvent to the mixing container with operation of the impeller up to about a coacervation point, (2) at about the coacervation point, matching the countersolvent addition rate and impeller speed to obtain a desired particle size distribution of the particles aggregated with the binder, and (3) thereafter adding excess countersolvent to the mixing container;
• and (b) a liquid removal routine for stopping the impeller, allowing particles to settle in the mixing container and actuating a valve in the decanting line to remove supernatant liquid from the mixing container.