Water is injected into the second chamber of the mill to provide evaporative cooling. Much of the energy consumed by a ball mill generates heat. The mill productivity also depends on many other factors, including the physical-chemical properties of the feed material, the filling of the mill by balls and their sizes, the armor surface shape, the speed of rotation, the milling fineness, and the timely moving off of the ground product.įig. The optimum ratio between length L and diameter D, L: D, is usually accepted in the range 1.56–1.64. The productivity of ball mills depends on the drum diameter and the relation of ∫ drum diameter and length.

Generally, filling the mill by balls must not exceed 30%–35% of its volume. With excessive filling, the rising balls collide with falling ones. The degree of filling the mill with balls also influences the productivity of the mill and milling efficiency.

Generally, a maximum allowed ball size is situated in the range from D/18 to D/24. Where d b.max is the maximum size of the feed (mm), σ is the compression strength (MPa), E is the modulus of elasticity (MPa), ρ b is the density of material of balls (kg/m 3), and D is the inner diameter of the mill body (m).

Ball high tor paper