. How Jet Mills Work | The Jet Pulverizer Company Size reduction is the result of the high-velocity collisions between particles of the process material itself. The interior of the chamber is designed to allow recirculation of over-sized particles, enhancing the incidence and the effect of these collisions. As particles are reduced in size and progressively lose mass, they naturally migrate toward the central discharge port, making precise ... size reuction versus time for ball mill size reuction versus time for ball mill