Determination of critical speed of ball mill

Ball Mill-A ball mill consists of a hollow cylinder mounted such that it can be rotated on its horizontal longitudinal axis.

Grinding Parameters in Ball Mill: The most important grinding parameters are:

1. Feeding arrangement.
2. Particle size of the feed
3. Grinding media-material, size, and quality.
4. Mill size, its speed and power consumption.
5. Solid-liquid ratio and circulating load in a closed circuit operation.

If mill rotate very fast centrifugal force keeps the balls in contact with wall and with each other during the upward movement. While in contact with the wall, the balls do some grinding by slipping and rolling over each other, but most of the grinding occurs at the zone of impact, where the free-falling balls strike the bottom of the mill. If the speed is too high, however, the balls are carried over and the mill is said to be centrifuging. The speed at which centrifuging occurs is called the critical speed. Little or no grinding is done when a mill is centrifuging, and operating speeds must be less than the critical

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