Application of ultrasound in comminution.

This paper deals with a new technology for fine grinding of hard materials, based on a high-compression roller mill with ultrasonic capabilities. The machine was tested by producing fine powders from hard rocks, with and without ultrasonic activation, permitting the beneficial effects of ultrasound to be evaluated. The experimental set-up allows the following operational parameters to be measured: material flow, applied torque, angular velocity of the rollers, stress on the shafts, ultrasonic energy applied and the vibration amplitude and phase behaviour of the transducer roller.