HORIZONTAL/ TUBE / BALL MILL
A ball mill is a type of grinder used to grind and blend materials for use in various types of industries. A ball mill works on the principle of impact: size reduction is done by impact as the balls drop from near the top of the shell.
A ball mill consists of a hollow cylindrical shell rotating about its axis. The axis of the shell may be either horizontal or at a small angle to the horizontal. it is partially filled with balls/ Grinding Media. The inner surface of the cylindrical shell is usually lined with an abrasion-resistant material such as steel or rubber.
In case of continuously operated ball mill, the material to be ground is fed from the feed end/ left and the product is discharged through to the right/ discharge end. As the shell rotates, the balls are lifted up on the rising side of the shell and then they cascade down (or drop down on to the feed), from near the top of the shell. In doing so, the solid particles in between the balls are ground and reduced in size by impact.
Thermal Power Plants
These are normally mono chamber drum type structure, in which balls (of certain sizes) are fed and then the Drum / Mill is rotated at a critical speed such that balls stick on and reach top (theoretically) or almost top and fall with gravity on coal, there by crushing it. Tube Mills is lined with Liners so that the mill shell does not get damaged. The mill is charged with Grinding Balls, which performs the function of grinding.