Influencing factors of the degree of grinding of the ball mill

A ball mill also known as pebble mill or tumbling mill is a milling machine that consists of a hallow cylinder containing balls; mounted on a metallic frame such that it can be rotated along its longitudinal axis. The balls which could be of different diameter occupy 30 – 50 % of the mill volume and its size depends on the feed and mill size. The large balls tend to break down the coarse feed materials and the smaller balls help to form fine product by reducing void spaces between the balls. Ball mills grind material by impact and attrition.

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The degree of milling in a ball mill is influenced by;
a. Residence time of the material in the mill chamber.
b. The size, density, and number of the balls.
c. The nature of the balls (hardness of the grinding material)
d. Feed rate and feed level in the vessel.
e. Rotation speed of the cylinder.