There is another important systematic reason that affects the wear, breakage, and loss of roundness of steel balls, namely the grinding process conditions and mill operating conditions. Only by systematically integrating and analyzing these two factors can we truly grasp the key to correctly selecting and using steel balls, and thus achieve the ultimate goal of helping the grinding system achieve high, stable, and low consumption. Let's analyze and discuss these two factors one by one.
1、 Grinding process conditions
1. The metal abrasiveness, fragility, and grindability of incoming materials. As we have described in the previous lectures, it can be said that ores with the same chemical composition and sometimes even the same hardness will have significant differences due to their different internal cleavage degree, natural fracture development, and weathering degree. For cement plants, not to mention those from different mining sites, even if the ore from different mining faces in the same mining site is different, the differences in metal abrasiveness, fragility, and grindability can lead to changes in steel ball wear.
2. Hardness of incoming materials
The effect of the relative hardness of the material on the wear of steel balls when other conditions are the same when grinding the material.
When the hardness HQ of the steel ball is equal to the hardness HW of the ground material, that is, when the relative hardness H=HQ/HW=1, the wear of the steel ball is most severe.
When the relative hardness H ≥ 1 or H ≤ 1, the wear of the steel ball is significantly reduced. When H ≥ 3, increasing the hardness of the steel ball results in minimal wear reduction. At the same time, excessive hardness leads to a decrease in toughness and an increase in ball breaking rate, which is even more counterproductive.
In dry wear, determining the relative hardness appropriately has a particularly significant effect on reducing steel ball wear. The hardness of the steel ball should be selected based on the hardness of the material, and attention should be paid to the matching of hardness between the steel ball and the material in production.
3. Particle size of incoming materials
As the particle size of the grinding material increases, the wear of the steel ball also gradually increases. When the ratio of material particle size d to mill inner diameter D reaches 1.25 × 10-3, the wear of the steel ball reaches its maximum value. This is because the adsorption of materials on the surface of steel balls is reduced, resulting in a reduced protective effect. But as the particle size of the material continues to increase, the material separates the steel balls and reduces the chance of direct contact between the steel balls, so the wear of the steel balls gradually decreases.
4. When the fineness of the finished steel ball is very fine, it is often due to the phenomenon of material wrapping on the surface of the steel ball, which reduces the wear of the steel ball.
For wear-resistant steel ball manufacturers, understanding these factors that have an impact on steel balls is necessary to strive for technological breakthroughs, continuously pursue new technologies and research, improve the efficiency of wear-resistant steel balls, and achieve the ultimate goal of high, stable, and low consumption in the grinding system.
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