Effects of Grinding Media on Ultrafine Grinding

1. Influence of Grinding Media Hardness and Density:

The density and hardness of grinding media significantly impact grinding efficiency. Higher media density results in increased grinding efficiency, while higher hardness reduces wear and ensures better product purity. However, under conditions of fixed slurry density and viscosity, excessively high density and hardness may not necessarily be advantageous. Pursuing excessively high density and hardness can escalate costs and lead to adverse effects.

Excessively high-density grinding media can cause uneven distribution within the container. Moreover, greater differences in density result in unreasonable distribution, increasing the probability of mutual compression among the grinding media. Lighter compression leads to media wear and decreased grinding efficiency, while heavier compression may crush or fracture the grinding media, shedding substantial particles into the product and causing uncontrolled larger particle sizes.

Greater hardness typically implies poor toughness and reduced impact resistance. During high-speed impact (collisions) between the grinding media and the material being ground, the grinding media itself is prone to breakage, increasing the likelihood of self-damage and being shattered by other grinding media.

2. Influence of Grinding Media Size:

The specific surface area of the grinding media significantly influences grinding efficiency. Smaller grinding media results in a larger specific surface area, leading to increased contact area between the media and the material, thereby enhancing grinding efficiency.

The speed of grinding in stirred mills is primarily related to factors such as the contact area of the media ball, collision frequency, volume of powder squeezed into the contact points of the two balls, the form and magnitude of external forces applied to the two balls and the material being squeezed, and the mechanical strength of the material being ground.

The size of the grinding media should be determined based on the particle size of the material and the desired product size. Finer product sizes require smaller media sizes; typically, the media size should be greater than 50-100 times the average particle size of the feed material.