How To Select Zirconium Beads, Zirconia Beads And Glass Beads For Grinding

With the increasing requirements for the fineness of materials, the use of sand mills is becoming more and more common, and there are more grinding media in the market. How to choose a grinding medium that is more suitable for its own production process and conditions is a key and laborious matter. The following aspects are briefly analyzed.
1、 Chemical composition
According to different materials, grinding media can be divided into glass beads, ceramic beads (including zirconium silicate beads, composite zirconium beads, alumina beads, rare earth metal stabilized zirconia beads, etc.), steel beads, etc. Due to the difference in chemical composition and manufacturing process, the crystal structure of grinding beads is determined. The compact crystal structure ensures the high strength, high wear resistance and low ink absorption of the beads. The percentage content of various components determines the specific gravity of the grinding beads, and the high specific gravity ensures the grinding efficiency; The natural wear of the chemical composition of the grinding beads during the grinding process will have a certain impact on the performance of the slurry, so in addition to considering the low wear rate, the chemical elements to be considered are also factors to be considered. For example, grinding tape powder or other electronic component paste, metal elements such as Fe and Cu should be avoided, and grinding beads containing Fe2O3 or CuSO4 are not included in the selection, so zirconium beads are often the common choice in this industry; For example, in terms of grinding pesticides, medicine and biochemistry, heavy metals are taboo elements, while PbO is the most common component. In short, some physical properties (hardness, density, wear resistance) determined by the chemical composition of the beads and the pollution of the slurry caused by their own abrasion are the factors to be considered in selecting the grinding medium.
2、 Physical properties:
1. Density of grinding medium
Density is usually expressed in specific gravity (true specific gravity) and bulk weight (false specific gravity). The molecular weight and percentage composition of various oxides determine the grinding density. The density of commonly used grinding media is shown in Table 1.
Generally, the larger the specific gravity of the grinding ball, the greater the impulse, the higher the grinding efficiency, and the greater the wear of the contact parts (inner cylinder, dispersion plate, etc.) of the grinding mill, so the matching of the viscosity and flow of the slurry becomes the key. Low density grinding beads are suitable for low viscosity slurry, and high density grinding beads are suitable for high viscosity slurry.
2. Particle size of grinding medium
The size of the grinding bead determines the number of contact points between the grinding bead and the material. The more contact points of the beads with small particle size in the same volume, the higher the grinding efficiency in theory; On the other hand, when grinding materials with relatively large particles in the initial test, for example, for 100 microns of slurry, the beads with D=1mm are not necessarily used, because the impulse of small beads can not reach the energy of sufficient grinding dispersion, so the beads with larger particle size should be used.
3. Hardness of grinding medium
Mohs and Vickers hardness are commonly used indicators. The higher the hardness of grinding beads, the lower the wear rate of beads does not mean. The hardness of commonly used grinding media and other materials is shown in Table 2.
For example, from the wear of grinding beads on the contact parts of the grinding mill (dispersion plate, rod pin, inner cylinder, etc.), the wear of grinding beads with high hardness on the contact parts is greater, but the best optimization point can be reached by adjusting the filling amount of the beads, viscosity, flow and other parameters of the slurry.