As we know, the rotation number of a ball mill can directly determine the motion state of the steel balls inside the tube of the ball mill and the effect of the ore grinding operation process.

When the rotation number is quite small, the height which the steel balls inside the ball mill are lifted up to is small. Because of the gravity of the steel balls, they will slide down from the top of the ball mill tube. At this time, the impact force of the balls is small but the grinding function of them is very strong. Ore is crushed mainly by grinding. But the ore grinding effect is not so good.

When the rotation number is quite big, the steel balls are lifted highly. When the steel balls have been lifted up to a certain height, they will separate themselves from the tube of the ball mill. Then, they will fall down along a parabola, which means they keep in the casting and falling state. There is a quite strong impact function at the drop point. Ore is crushed mainly by the impact force. And the ore grinding efficiency is the highest.

When the rotation number of a ball mill has surpassed a certain limit, which means the rotation number is very big, the steel balls are rotating with the tube’s rotation and they will not fall down. At this time, they are in the centrifugal operation state. The balls have no impact function. And the ore grinding function is very small which will stop the ore grinding function.