On the misunderstanding of judging the quality of ball mill steel ball and its influence

The steel ball quality of ball mill not only affects the productivity, but also affects the ball consumption, and then affects the grinding medium cost. It is wrong to simply pursue high hardness and low unit consumption. High hardness and low unit consumption do not mean low cost. Balls with high hardness and low unit consumption often have high prices. High hardness does not necessarily increase or even decrease productivity. Only high productivity can reduce various unit consumption indicators. Therefore, the primary criteria for selecting steel balls should be high mill productivity and low grinding medium cost. Only high productivity and low grinding medium cost can have good economic benefits. Economic benefit is a necessary condition for the survival and development of enterprises.

When selecting steel balls, two problems are often ignored: the harder the steel ball is, the better it is, but it has its appropriate hardness value; The density of steel ball is also a problem that can not be ignored. As for the influence of hardness, generally speaking, with the increase of hardness, as long as there is no crushing, the unit consumption of steel ball decreases; Moreover, the deformation of the ball is small. In crushing, the deformation of the ball is small, and more energy can be used to crush ore particles, which can increase the productivity of the mill. However, the increase of ball hardness can only be moderate, with an appropriate range, not the harder the better. If only the ball consumption is considered, the higher the hardness, the lower the consumption. However, for the mill productivity, within a certain range, the productivity increases with the increase of steel ball hardness, but when the hardness exceeds a certain range, it will have an adverse impact on the mill productivity and reduce the mill productivity. When the hardness of steel ball is too high, it is unfavorable to grinding for two reasons:

① The rebound bounce of the steel ball is serious, which causes part of the energy loss in the rebound, so the energy of the steel ball is not more used for crushing, so it affects the crushing;

② When the hardness of the steel ball is too high, the sliding between the balls is severe when they are in contact with each other, which can not effectively engage the ore particles between the KIR waves, so that the grinding effect of the ore particles is weakened.

As for the influence of steel ball density on grinding, generally speaking, the productivity of balls with the same size with high density is large, and the productivity of balls with low density is small.

Ball density is affected by three factors:

① The density of different materials is different. The density of steel is greater than that of cast iron. Alloy steel varies according to the density and content of main alloy elements.

② Due to the influence of the manufacturing method of steel ball, the structure of rolled and forged steel ball is dense, so the density is large. The structure of cast steel ball, cast iron ball or cast alloy ball is not very dense, and even there are pores, so the density is small.

③ The density of martensite, austenite, bainite, ferrite and other different crystal structures is also different, which also has an effect on the crystal fineness.