Five star heavy industry technology: how to load ball mill

The main function of the ball in the ball mill is to crush and grind the mineral. Therefore, to mix the ball of the ball mill is to meet the purpose of crushing and grinding the mineral. The crushing effect directly affects the grinding efficiency and ultimately the overflow amount of ball milling. The grading of the ball is directly related to the crushing effect. The grading of ball loading includes the size of ball, the proportion of balls of various sizes, and the number of ball diameter. These parameters are mainly affected by the ball mill specifications, ball mill internal structure, product fineness requirements and other factors, and at the same time, the material characteristics into the mill should be considered.

Firstly, the ball loading should have enough impact force to make the ball have enough energy to crush the grinding material, which is directly related to the maximum ball diameter of the steel ball.

Secondly, it is necessary to have enough impact times before the ball can crush the material, which is mainly affected by the average diameter of the ball and the filling rate of the ball. When the loading amount is fixed and enough impact force is ensured, the impact times on minerals can be increased by reducing the diameter of spheres and increasing the number of spheres, so as to improve the crushing efficiency.

Thirdly, in order to ensure that there is sufficient grinding time for the material in the mill, the ball must have the ability to control the flow rate of the material to ensure that the material is fully crushed.

Two graded ball rule

Two kinds of spheres with different sizes are used for grading, and the diameter difference between the two kinds of spheres is large. The main reason is that the packing density of steel balls can be significantly increased by filling small balls between big ones. Its main function is to improve the impact capacity and impact times of the mill. In addition, the high packing density can make the material fully grinded.

In the principle of two graded balls, the main function of the big ball is to impact and crush the material, while the small ball is to fill the gap of the big ball to improve the packing density of the ball, control the flow rate of the material and increase the grinding capacity; the second is to transfer the impact energy of the big 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.

Several parameters need to be determined in the two graded ball method

1. Determine the diameter of the big ball. It depends on the size of the ball mill, the size of the material into the mill and the degree of easy grinding. Generally, the diameter of the second stage ball in the multi-stage ball matching shall prevail. If the maximum ball diameter of a ball mill in multi-stage ball distribution is 100 mm, the steel ball with diameter of 90 mm should be selected for two grading balls.

2. Determine the diameter of the small ball. It depends on the size of the gap between the big balls, that is, the diameter of the big balls. Generally, the small ball diameter is 20% - 30% of the big ball diameter.

3. The ratio of big and small balls. In principle, it should be ensured that the addition of small balls does not affect the filling rate of large balls. Generally, small balls account for 3% - 5% of the weight of large balls.

In multi-stage ball matching, the requirements of impact force, impact times and material flow control ability of steel ball are mainly based on the average ball diameter, that is to say, it is affected by various sizes of balls. In the two graded balls, the impact force and impact times of the steel ball are determined by the diameter of the large ball, while the ability to control the material flow rate is mainly determined by the diameter of the small ball and the loading amount, and the influence of the diameter of the large ball is very small. Therefore, the contradiction between the impact force, the impact times and the control material flow rate energy is alleviated. In contrast, the two grading ball method is relatively simple and easy to take into account when determining the grading parameters.

With the increase of material hardness and particle size (which can be reflected by the different mixing amount of admixture), the contradiction between the impact force of steel ball and the control ability of material flow rate in multi-stage ball mixing becomes more prominent, so the output decreases more obviously. However, there is no such contradiction in the two graded balls, because it can meet the requirements of impact force and flow rate control ability of materials through large and small balls, so the output change is not obvious, which reflects the advantages of the two graded balls.

The use of two graded balls can also reduce the times of cleaning. It only needs to be supplemented regularly according to the output, current, fineness and ball consumption ratio of grinding materials. In addition to special circumstances, it is generally not shut down to clear the warehouse, which improves the operation rate of the ball mill.

conclusion

When the particle size of the material is small and the grindability is good, the multi-stage ball mixing should be adopted, because it is important to increase the impact times of steel ball at this time. On the contrary, when the particle size of the material is large and the strength is high, it is the key to improve the impact force of the steel ball.

The use effect of the two kinds of ball mixing is greatly different by the change of materials. The multi-stage ball mixing is more sensitive to the change of materials, and the output of ball mill fluctuates greatly. The two graded balls are not sensitive to the change of materials, and the output is relatively stable. That is to say, when the grindability of the material is better, the increase range of multi-stage ball blending is higher than that of two graded balls. On the contrary, the decline degree of multi-stage ball blending is more than that of two graded balls. Therefore, the multi-stage ball is suitable for the materials with smaller particle size and better grindability, while the two graded balls are suitable for the materials with larger particle size and poor grindability