Abstract
Ball mill is a kind of grinding equipment in the mineral and chemical processing industry. Many balls called media are put into a mill with material, and the mill is rotated. Material is grounded by collision force due to contact between the material and the balls or mill wall. During operation, mills emit vibration and sound. The vibration and sound of mills contain information related to inside of the mill and are useful for operation control. If the relationship between the internal status and the measured vibration and sound signals is clarified, we are able to estimate the internal status of the mill. In this study, we develop a simulation model for analysis of structure-borne sound of the ball mill during the operations. At first, the motion of balls and material to be ground in the mill is simulated by discrete element method. After that, the vibration of the wall of the mill and the radiated sound are estimated. As a result, it is found that both the amplitude of the vibration response and the radiated sound increase in each peak frequency as the rotation speed increases. When the rotation speed increases, the highest point of the balls and material become high. Therefore, the balls and material collide with the wall surface of the mill at high translational speed, and the exciting force to the mill wall becomes large. Moreover, the difference in the amplitude value of the peak frequency clearly occurred at high rotation speed.
