Views: 1 Author: Site Editor Publish Time: 2022-02-02 Origin: Site
There are certain skills when using zirconia ball milling beads. For example, selecting appropriate zirconia beads will have different effects on grinding, so as to increase or reduce wear. Therefore, it is very necessary to select appropriate zirconia beads.
1、 Effect of zirconia bead selection on grinding
Mohs and Vickers are commonly used indicators. Generally, the higher the hardness of zirconia beads, the lower the wear rate of beads. From the wear of zirconia beads on the contact parts (dispersion plate, rod pin and inner cylinder, etc.) of the sand mill, the wear of zirconia beads with high hardness on the contact parts is larger, but the wear of beads with smooth surface on the cylinder and dispersion plate is relatively small. At the same time, a better optimization point can be achieved by adjusting the filling amount of grinding beads, material viscosity, flow and other parameters.
(2) Particle size
The size of zirconia beads determines the number of contact points between beads and materials. The more contact points of beads with small particle size under the same volume, the more effective collision times in the grinding process, and the higher the grinding efficiency. At the same grinding time, when using small diameter grinding beads, the fineness of the product is better than that of large diameter grinding medium. On the other hand, when grinding materials with relatively large initial particles, for example, for materials with 100 microns, beads with d = 1mm are not necessarily used because the impulse of small beads cannot reach the energy of full grinding dispersion. At this time, beads with larger particle size should be used.
Density is expressed by density (true density) and bulk density (false density) in normal documents. The molecular weight and percentage composition of various oxides determine the density of zirconia beads. Generally, the higher the density of zirconia beads, the greater the kinetic energy generated with the rotation of the grinder and the higher the grinding efficiency. On the other hand, the higher the density of grinding medium, the greater the wear of the contact parts (inner cylinder, dispersion plate, etc.) of the sand mill, so the matching of material viscosity and flow becomes the key. Low density zirconia beads are suitable for low viscosity materials, and high density zirconia beads are suitable for high viscosity materials.
2. Reasonable filling rate
The filling rate of zirconia beads is the number of grinding beads required by the sand mill for better dispersion grinding effect. The filling rate of grinding beads is too high, which is easy to cause the internal temperature of the grinder to rise, and the cylinder can not dissipate heat in time and shut down automatically. The filling rate of grinding beads is too low, the grinding efficiency is low, and the medium loss is large. Therefore, reasonable filling rate is one of the important factors to improve grinding efficiency.
The volume measurement method is often used to express the filling rate in the operation manual of the sand mill, but it must be converted into the actual filling quality of the medium in production. Calculation formula = effective volume of sand mill × Filling rate × Bulk density of grinding medium
2、 Supplement grinding medium
1. Principle of adding grinding medium
If the grinding efficiency of the grinder is found to be reduced, it is a possible signal to add beads. Users can screen and add beads regularly according to their own process conditions and master the actual loss rate of beads.
2. How to supplement grinding medium
Due to the natural loss of beads, the particle size of beads will be smaller and smaller. In order to maintain a unified filling amount and avoid fine beads from blocking or entering the separation device, the beads should be screened and a certain amount of grinding medium should be supplemented according to the service life of grinding medium and the conditions of users' own process. Shanghai rute's suggestion is to check the wear of beads after 500-600 working hours and reasonably add an appropriate amount of new beads.