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.
Based on various kinds of requirements, various grinding principals are applied and different kinds of mills are used in mining industry.
A rotating drum causes friction and attrition between steel rods and ore particles. Rod mills are less common than ball mills for grinding minerals.
Ball Mills are typically used in secondary grinding, after the primary grinding in AG/ SAG Mills.
AG/ Autogenous Mill
Autogenous or autogenic mills are so-called due to the self-grinding of the ore a rotating drum throws larger rocks of ore in a cascading motion which causes impact breakage of larger rocks and compressive grinding of finer particles. It is similar in operation to a SAG Mill as described below but does not use steel balls in the mill. Also known as ROM or “Run of Mine” Grinding.
SAG is an acronym for Semi-Autogenous Grinding. SAG mills are essentially Autogenous mills, but utilize Grinding Balls to aid in grinding like in a Ball Mill. A SAG Mill is generally used as a primary or first stage grinding solution.