The main function of steel balls in
ball mill equipment is to impact and crush materials, but also play a certain role in grinding. Therefore, the purpose of grading steel balls is to meet these two requirements. Whether the grinding effect is good or not directly affects the grinding efficiency and ultimately affects the output of ball mill equipment depends on whether the gradation of steel balls is reasonable, mainly including the size of steel balls, the number of ball diameters, the proportion of balls of various specifications and so on.
In order to determine these parameters, we should consider not only the size of
ball mill equipment, internal structure of ball mill equipment, product fineness requirements and other factors, but also the characteristics of grinding materials (grindability, particle size, etc.).
In order to effectively crush materials, the following principles must be followed in determining gradation:
Firstly, the steel ball must have enough impact force to make the ball mill equipment have enough energy to break down particulate matter, which is directly related to the maximum diameter of the ball.
Secondly, the steel balls should have enough impact times on the material, which is related to the filling rate of the steel balls and the average diameter of the balls. When the filling quantity is fixed, on the premise of ensuring enough impact force, the diameter of the abrasive body should be reduced as far as possible, and the number of steel balls should be increased to increase the impact times on the material, so as to improve the crushing efficiency.
Finally, the material has enough residence time in the mill to ensure that the material is fully crushed, which requires the steel ball to have a certain ability to control the material flow rate.
The so-called two-stage ball distribution method is to use two different sizes of steel balls with large diameter difference for grading. The theoretical basis is that the voids between big balls are filled by small balls to fully increase the packing density of steel balls. In this way, on the one hand, the impact capacity and times of the mill can be improved, which accords with the functional characteristics of the grinding body. On the other hand, the higher packing density can make the material get a certain grinding effect. In the two-stage distribution ball, the main function of the big ball is to break the material by impact. The small ball fills the gap between the big balls and increases the accumulation density of the grinding body to control the material flow rate and increase the grinding ability. The second is to transfer the impact energy of the ball to the material. The third is to squeeze out the coarse particles in the gap and place them in the impact zone of the big ball.
