SIMULATION OF BALL BEHAVIOR IN A VIBRATION MILL IN RELATION WITH ITS GRINDING RATE - EFFECTS OF FRACTIONAL BALL FILLING AND LIQUID VISCOSITY

The motion of balls in a two-dimensional vibration mill was investigat ed by means of a simulation method called Discrete Element Method, whi ch made it possible to calculate the intensity and frequency of ball c ollisions. The effects of vibration conditions and fractional ball fil ling on the characteristics of ball collisions and the grinding rate w ere investigated by the simulation as well as the grinding experiment. Taking account of the strength of particles to be ground, effective b reaking collision frequency was defined as the frequency of ball colli sions greater than the particle breakage strength and compared with th e grinding rate experimentally obtained. These results from the simula tion and the grinding experiment agreed well regardless of the grindin g conditions, Furthermore, the effects of the viscosity of liquid in t he mill pot on the movement of balls, intensity and frequency of ball collisions were quantitatively discussed for a special case where the mill pot was completely filled with the liquid and balls.