Ball mill external appearance and internal view.īall mills are filled up to 40% with steel balls (with 30–80 mm diameter), which effectively grind the ore. 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.įigure 8.11.

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). The mill productivity also depends on many other factors: physical-chemical properties of feed material, filling of the mill by balls and their sizes, armor surface shape, speed of rotation, milling fineness and timely moving off of ground product.ĭ b. Optimum ratio between length L and diameter D, L: D is, usually, accepted in the range 1.56–1.64.

Productivity of ball mills depends on drum diameter and the relation of drum diameter and length. Generally, filling the mill by balls must not exceed 30–35% of its volume. The degree of filling the mill with balls also influences 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 feed (mm) σ is compression strength (MPa) E is modulus of elasticity (MPa) ρb is density of material of balls (kg/m 3) D is inner diameter of the mill body (m).

Bricks n balls ball size