An Investigation into the Relationships Determining Ball Trajectory in Mills by Using the Physical Modelling

Since software packages, which predict the charge motion of single ball in the mineral processing tumbling mills, use the Powell (1991) relationships, the accuracy of these relationships was investigated in this research. The test results indicated that the difference between the impact points for two balls with different materials was lower than 2o. A change in friction coefficient had no significant effect on the ball impact point, whereas in the Powell relationships changing the friction coefficient to 0.4 increased the impact point difference 15o. The friction coefficient in the Powell relationships considers to be more than zero at the point of equilibrium. The impact point difference between the results from the Powell relationships and the relationships that considers static friction coefficient (µs) equal to zero at the point of equilibrium were compared. The results indicated that the difference is negligible when µs is near to zero and is high when µs is more than 0.1.