How to Choose Suitable Grinding Media

As the demand of the material fineness is higher and higher, sand mill will be widely used in the industry, but on the market with so much grinding media, how to choose a more suitable grinding media for their own production technology and condition, which is a more critical and demanding thing. Here are some aspects as simple analysis.

I. chemical composition of grinding media

Grinding media can be divided into glass beads, ceramic beads and steel balls according to the different materials . The difference of chemical composition and manufacturing process determines the crystal structure of the grinding beads, and dense crystal structure ensures the high strength of beads, high abrasion resistance and low ink absorption rate, etc. The different percentage content of various components determines the proportion of the grinding beads, and high proportion can guarantee the grinding efficiency; Chemical composition of grinding beads has some influence on the performance of the slurry on the wear and tear in the process of grinding, so the chemical element is also a factor to consider in addition to the low wear rate. And powder grinding magnetic tape or other electronic components and Fe and Cu of metal elements, they all should be avoided. What’s more, mill beads containing ingredients like Fe2O3 or CuSO4 should also be out of place in the selection. Therefore, the zirconium bead is the popular choice in the industry; In the grinding of pesticide, medicine and biochemistry, heavy metal is scruples element, and PBO is one of the most common ingredients.

In short, some physical properties (hardness, density and wear resistance) determined by the chemical composition of the beads, and slurry pollution situation of abrasion of grinding media both need to be considered when choosing grinding media.

II. physical performance of grinding media

a.The density of grinding media

Density in the file is usually stated as specific gravity (true) and bulk weight (false). On normal circumstance, the greater the proportion of grinding beads, the greater the impulse and the higher grinding efficiency. For the contact elements (cylinder, scattered disk, etc.) of sand mill, their abrasive wear is relatively large, so the slurry viscosity and flow become the key. Low density mill beads are suitable for low viscosity of slurry, and high density grinding beads are suitable for high viscosity pulp.

b.     The hardness of grinding media

Mohs hardness (Mohs) and Vickers hardness (Vickers) are commonly used indicators. With the higher the hardness of grinding beads, the wear rate of beads does not represent a lower level. From grinding beads for sand mill contact elements (dispersion plate, rod pin, cylinder, etc.) within the wear, the stronger hardness of grinding beads, its contact abrasion is bigger, but it can be adjusted on the filling amount of beads, the paste viscosity and flow parameters so as to achieve the best optimization.

c.     The particle size of grinding media

The size of grinding bead determines the number of its contact points with material, and the more contact points of beads in small particle size in the same volume, the higher grinding efficiency theoretically; on the other hand, when trying a larger particles of material, like 100 microns, D=1mm beads may not be used. The reason is that the impulse of beads can not reach the energy scattered from full grinding, so the beads in larger particle size should be used at that time.