Excessive Zirconia Bead Loading Causes Horizontal Sand Mill to Jam

Our customer in Shijiazhuang is in the building materials industry, specifically producing talcum powder. They use a 30L horizontal sand mill machine with yttria-stabilized zirconia beads. They initially added 75 kg of zirconia beads and 2.4 tons of material with a slurry solid content of 50%.

High-flow Sand Mill Machine:The sand mill machine is equipped with a 22 kW motor. The customer reported that the machine stops running after a period, experiencing a lack of power. Initially, they suspected an issue with the motor, but upon inspection by the equipment maintenance team, the motor was found to be in good condition. The drive belt connecting the motor to the sand mill was also intact. Loose drive belts can cause stoppages, but this was not the case.

The machine runs smoothly without any issues when operating without material.

To troubleshoot the problem, they conducted tests by adjusting the amount of zirconia beads and material. After observing that the machine stopped with a current reading of 48A (normal for a 22 kW machine is around 40A), they determined that excessive zirconia bead loading was the issue. They reduced the zirconia bead quantity from 75 kg to 65 kg, and after a few days of testing, everything operated normally.

For horizontal sand mill machines, the zirconia bead loading is typically around 60-80%. In this case, they calculated it at 70%. The calculation method is: 30L * 0.7 (70% for the horizontal sand mill) * 3.6 (stacking density of yttria zirconia beads) = 75.6 kg. However, they found that the initial loading was too high and recommended testing with 60% loading.

Here are the operating instructions for the sand mill machine:

1. After prolonged shutdown, check whether the dispersion plate is stuck with medium. If the coupling cannot rotate, use a pump to inject solvent. Wait for dissolution before starting. Do not force start to avoid damaging the friction plate.

2. Before starting after prolonged shutdown, check if the top sieve screen has hardened paint slurry. If so, clean it with solvent to prevent screen blockage, which could lead to overflow.

3. If a "top overflow" occurs, stop the machine immediately, clean the sieve screen, place a receiving pan, adjust the slurry pump speed, and restart. Failure to do so may allow paint slurry to enter the main spindle bearing, leading to bearing wear or damage to the feed pump.

4. Never start the machine when there is no paint or grinding medium inside the cylinder.

5. When cleaning the cylinder with solvent, only rotate the disperser slightly and intermittently to prevent component wear.

6. When using new sand, regularly clean the sieve to remove impurities and foreign objects. The sand mill machine should also be cleaned and replenished with new sand.

7. Ensure that the observation window is intact to prevent injury accidents caused by sand spillage during machine operation.