Application Skills of Zirconia Ball Milling Beads
There are certain skills in the use of zirconia balls. For example, choosing the right zirconia beads will affect grinding differently, increasing or decreasing wear. Therefore, it is very necessary to select suitable zirconia microbeads.
The influence of the selection of zirconia beads on grinding
Mohs hardness and Vickers hardness are commonly used indicators. Generally, the harder the zirconia beads, the lower the wear rate of the beads. From the wear of zirconia beads at the contact parts of the sander (dispersing plate, rod pin, inner cylinder, etc.), the zirconia beads with high hardness in the contact parts wear more, but the zirconia beads with smooth surfaces of the cylinder and the dispersing plate wear relatively smaller. At the same time, parameters such as the filling amount of abrasive particles, material viscosity and flow rate can be adjusted to achieve a better optimization point.
(2) Particle size
The size of the zirconia beads determines the number of contact points between the beads and the material. Under the same volume, the more contact points of beads with small particle size, the more effective collisions during the grinding process, and the higher the grinding efficiency. Under the same grinding time, when using small diameter grinding beads, the product fineness is better than when using large diameter grinding media. On the other hand, when grinding materials with relatively large initial particles, for example, for 100 micron materials, it is not necessary to use beads with d = 1 mm, because the impulse of small beads cannot reach the energy of complete grinding dispersion. In this case, beads with a larger particle size should be used.
(3) Density
In general documents, density is expressed in terms of density (true density) and bulk density (false density). The molecular weight and percent composition of the various oxides determine the density of the zirconia beads. Generally, the higher the density of zirconia beads, the greater the kinetic energy generated by the rotation of the mill, and the higher the grinding efficiency. On the other hand, the higher the density of the grinding medium, the greater the wear of the contact parts of the sand mill (inner cylinder, dispersing plate, etc.), so the matching of material viscosity and flow becomes the key. Low density zirconia beads are suitable for low viscosity materials, while high density zirconia beads are suitable for high viscosity materials.
Reasonable fill rate
The filling rate of zirconia microbeads is the number of grinding microbeads required by the sand mill for better dispersion and grinding effect. If the filling rate of grinding beads is too high, it is easy to cause the internal temperature of the grinding machine to rise, and the cylinder cannot be cooled in time and automatically stops. The filling rate of grinding beads is too low, the grinding efficiency is low, and the medium loss is large. Therefore, a reasonable filling rate is one of the important factors to improve the grinding efficiency.
In sand mill operating manuals, volume measurements are often used to express fill rates, but this must be converted to the actual fill mass of the media in production. Calculation formula = effective volume of sand mill × filling rate × grinding medium bulk density
2. Supplementary grinding media
1. The principle of adding grinding media
If you see a decrease in the grinding efficiency of the grinder, it may be a signal for the addition of beads. Users can regularly screen and add beads according to their own process conditions and the actual bead loss rate.
2. How to replenish grinding media
The particle size of the beads will become smaller and smaller due to the natural attrition of the beads. In order to maintain a uniform filling amount and avoid fine beads from clogging or entering the separation device, the beads should be screened and supplemented with a certain amount of grinding media according to the service life of the grinding media and the user's own process conditions.
