The actual operating speed of a ball mill typically ranges between 65% and 80% of its critical speed. For which of the following processes is it necessary to run the ball mill at the highest percentage of the critical speed?

Explanation

Ball mills are operated at different speeds depending on the material and milling conditions. When dry grinding large particles in mills lacking internal baffles, the mill must be run near the maximum critical speed to ensure adequate grinding action and particle breakage. Other conditions like wet grinding in low or high viscosity slurries or dry grinding with baffles require lower operating speeds.