A NUMERICAL-ANALYSIS OF MOVEMENT OF BALLS IN A VIBRATION MILL

To elucidate the grinding mechanism of a vibration ball mill, the movement of ball media in a two-dimensional pot with circular vibration was simulated by means of a numerical calculation technique called the discrete block method. The movement of balls was also analyzed with the aid of video pictures superimposed on a computer display. These results agreed well in terms of circulation of balls as well as distribution of ball number density and absolute velocity at different vibration settings, which proved the usefulness of this numerical calculation technique. The effects of vibration amplitude and frequency on the intensity and frequency of ball collisions obtained by this simulation were examined in relation to the grinding mechanism. It was confirmed that increase in vibration amplitude is more effective for improving grinding performance than is that of vibration frequency on the condition of constant vibration intensity, the former causing the increase of ball collision intensity and frequency while the latter leads to their decrease.