What measures can be taken to improve the grinding efficiency of the sand mill?

1. Optimize the use of grinding media
1. Choose the right grinding media material:
Choose grinding media according to the hardness and properties of the material. For example, for ceramic materials or mineral pigments with higher hardness, use zirconium oxide beads as grinding media. Zirconia beads have high hardness and good wear resistance, can withstand high-intensity collisions and friction, and grind hard materials more effectively. For organic pigments or food additives with lower hardness, glass beads may be sufficient, and the cost of glass beads is relatively low.
2. Control the size of the grinding media:
The size of the grinding media should match the initial particle size and target fineness of the material. If the initial particle size of the material is large, use a larger size (such as 1-3mm) of grinding media for coarse grinding to quickly break large particles. As the grinding progresses, when the particles gradually become finer, replace them with a smaller size (such as 0.1-0.5mm) of grinding media for fine grinding to improve the grinding accuracy. For example, in the production of coatings, for titanium dioxide with a larger initial particle size, coarse grinding with large beads first and fine grinding with small beads can effectively improve the grinding efficiency.
3. Adjust the filling rate of the grinding medium:
The appropriate filling rate of the grinding medium can improve the grinding efficiency. Generally, the filling rate is more appropriate between 60% and 80%. If the filling rate is too low, the contact opportunity between the grinding medium and the material is reduced, and the grinding efficiency is reduced; if the filling rate is too high, the movement of the grinding medium is restricted, which may cause the equipment to overload and also affect the grinding effect. Determine the optimal filling rate through experiments. For example, in the laboratory pilot stage, gradually adjust the filling rate, observe the grinding effect and equipment operation status, and find the optimal value.
2. Reasonably adjust the equipment operation parameters
1. Speed ​​control:
Select the appropriate sand mill speed according to the characteristics of the material and the grinding medium. The higher the speed, the greater the kinetic energy of the grinding medium, and the higher the grinding efficiency is usually, but too high a speed may cause problems such as increased equipment wear, excessive material temperature, and energy waste. For example, for a horizontal sand mill, when using zirconium oxide beads to grind pigments with higher hardness, the speed can be appropriately increased, but the bearing capacity of the equipment must also be considered, generally adjusted between 1000-1500rpm.
2. Feed speed adjustment:
Reasonably control the feed speed to ensure that the material can be fully ground in the grinding chamber. If the feed speed is too fast, the material stays in the grinding chamber for too short a time, and the grinding is not sufficient; if the feed speed is too slow, although the grinding effect may be better, it will reduce production efficiency. Adjust the feed speed by observing the quality of the output and the operating parameters of the equipment (such as current, temperature, etc.). For example, in the process of ink grinding, you can grind at a lower feed speed at the beginning, observe the fineness and color uniformity of the ink, and gradually increase the feed speed until you find an optimal feed speed that can ensure both grinding quality and production efficiency.
3. Grinding time setting:
Determine the appropriate grinding time through experiments. Different materials and grinding requirements require different grinding times. A particle size analyzer can be used to regularly detect the particle size of the material after grinding, and a curve of the change of particle size over time can be drawn to determine the time required to reach the target fineness. For example, in the process of drug micronization, the drug particles need to be ground to the micron level or even the nanometer level, and the grinding time is determined by experiment to avoid over-grinding or under-grinding.
3. Equipment structure improvement and maintenance
1. Improve the design of the disperser (stirring device):
Choose a suitable disperser type according to the grinding task. For example, the rod-pin disperser is suitable for grinding materials with high hardness or strong agglomeration because the rod pin can generate stronger shear force. At the same time, optimize the structural parameters of the disperser, such as the length, diameter, number and distribution of the rod pin, to improve the movement efficiency of the grinding medium. For example, increasing the number of rod pins can make the movement of the grinding medium more complicated, increase the collision and shearing opportunities with the material, and thus improve the grinding efficiency.
Regularly check and maintain the disperser to ensure its normal operation. Worn disperser parts (such as agitator blades, rod pins, etc.) will affect the movement of the grinding medium and reduce the grinding efficiency. Replace severely worn parts in time to ensure the performance of the disperser.
2. Optimize the grinding chamber design:
The shape and size of the grinding chamber will affect the movement of the grinding media and materials. For example, the special double-conical grinding chamber design can make the grinding media form a more complex circular motion in the chamber, increasing the chance of contact and collision with the material. At the same time, ensure the smoothness of the inner wall of the grinding chamber to reduce the energy loss of the grinding media and materials during the movement.
3. Ensure good mechanical seal:
A good mechanical seal can prevent material leakage, ensure the pressure in the grinding chamber is stable, and facilitate the full mixing and grinding of the grinding media and materials. Regularly check the wear of the mechanical seal and replace the seal in time to avoid the loss of efficiency due to poor sealing.
4. Material pretreatment and post-treatment
1. Material pretreatment:
Pretreatment of materials before grinding, such as screening to remove large particle impurities, pre-dispersion treatment to prevent material agglomeration, etc. For example, for pigment production, the pigment raw materials are pre-dispersed to form a more uniform dispersion system before entering the sand mill, which can improve the grinding efficiency of the sand mill because the grinding media can act more effectively on the dispersed material particles.
2. Material post-processing: Post-process the ground materials, such as using multi-stage filtration or centrifugal separation, to remove large particles and impurities that are not completely ground, so that the product quality is more uniform. At the same time, post-processing can recycle some of the underutilized materials and recycle them back to the sand mill for re-grinding, thereby improving the utilization rate of the materials and the grinding efficiency.