The size of the ball depends on factors such as the density of the ball, the particle size composition of the ore, the required product fineness, and the physical properties of the ore. 

According to general experience, the larger the ore block, the harder the ore, and the larger the ball diameter should be. However, when the particle size of the ore is small and the grinding product is required to be fine, it is not suitable to have too many large balls, and some small balls should be installed.

Adding unnecessarily large grinding balls not only increases the excessive crushing of the ore, but also increases the consumption of grinding balls.

The experiment shows that the larger the ball diameter, the faster the wear. When the grinding machine speed is high, the wear speed of the grinding ball is proportional to the third power of the ball diameter. When the rotational speed is low, the wear speed of the grinding ball is proportional to the quadratic power of the ball diameter. But grinding balls that are too small do not have a grinding effect. On the contrary, it occupies the volume of the grinding machine, consumes electrical energy, and affects the production capacity of the grinding machine. Grinding balls generally smaller than 10mm have very little grinding effect.

After correctly determining the size of the ball diameter, it is also necessary to determine the appropriate ratio for ball loading. In addition, the ball mill will continuously wear and tear the grinding ball during continuous operation. In order to maintain the appropriate filling rate and ball ratio of the ball, it is necessary to supplement the grinding ball reasonably to the grinding machine.