The function of the grinding body in the ball mill is to crush and grind the lumped material into fine powder. The particle size of the material just entered the mill is about 20mm, and it will eventually be ground into fine powder below 0.08mm (sieve residue can not exceed 15%). Grinding body to just feed the bulk material (coarse mill bin) to fierce impact, grinding as a supplement, mash them. During this period, the grinding bodies will inevitably collide with each other. The strong sound of mill operation mainly comes from the coarse mill bin. As the particle size of the material decreases, it will flow down the next warehouse, and the grinding body will turn to be mainly grinding, and the sound will gradually weaken. After grinding, it will be sent out of the mill.

Different types and specifications of grinding bodies are used in different grinding bins

Steel ball: one of the most widely used grinding bodies in ball mills. During the grinding process, it comes into contact with the material and has a large impact on the material. It is mainly used in the first bin (the feed end, which is also the coarse grinding bin), double The two chambers of the closed-circuit mill (coarse and fine grinding chambers), the first and second chambers of the tube mill. The diameter of the steel ball is between Ф15~125mm. According to the requirements of the grinding process, the coarse grinding chamber generally selects Ф50~110mm, and the fine grinding chamber uses various specifications of Ф20~50mm.

Steel section: In the fine grinding chamber of the mill, the material is mainly ground. The steel (iron) section can replace the steel ball. Its shape is short cylindrical or truncated cone. It has line contact with the material and has a strong grinding effect. The impact force is small, so it is more suitable for the fine grinding chamber.

Steel rod: Steel rod is a kind of grinding body commonly used in wet grinding, with a diameter of Ф40~90mm, and the length of the rod is 50~100mm shorter than the length of the grinding chamber.

Regardless of the type of grinding body, there are higher requirements for the material.

It must have high wear resistance and impact resistance. The quality of its material affects the grinding efficiency and the operation rate of the mill.

The material is required to be hard, wear-resistant and not easy to break. For example, high-chromium cast iron is an alloy white cast iron with high chromium content, which is characterized by wear resistance, heat resistance, corrosion resistance, and considerable toughness. Low chromium cast iron contains less chromium elements and has higher toughness. Chromium cast iron is poor, but has good wear resistance. It is suitable for use as the liner of small balls, iron sections and fine grinding chambers.