A partner once reached out for advice regarding their separator. After a period of operation, wear had occurred on the guide vanes, rotor blades, and labyrinth seal ring grooves. Coarse particles began appearing in the fine product, and adjusting the spindle speed of the separator failed to resolve the issue. Subsequently, a set of relevant spare parts was replaced. While this solved the problem of coarse particles in the cement, a new issue emerged—an increase in the water demand of the finished cement. The partner sought a solution from Engineer Mr. Zhang.
Mr. Zhang explained that research into the correlation between cement strength and particle size distribution has shown that cement particles in the range of 3–32 μm contribute most effectively to strength development, with the highest possible content of particles in the 16–24 μm range being particularly beneficial. Particles smaller than 1 μm are best avoided, as they become hydrated immediately during the mixing process and do not contribute to strength during hardening. Particles larger than 32 μm contribute very little to strength development until after 28 days, and from a commercial perspective, they mainly serve as filler.
In high-efficiency separator, labyrinth-type sealing ring grooves are typically used for sealing. The rotor, which undergoes rigorous dynamic balancing, operates smoothly. The fineness of the finished cement can be controlled by adjusting the rotor speed via the spindle frequency converter. However, if the labyrinth ring grooves experience excessive wear, causing the clearance between the grooves to exceed the specified range, the pressure differential between the inside and outside of the grooves increases. This allows coarse particles from the mixed powder fed to the distribution plate to bypass through the clearance and enter the air distribution chamber, ultimately mixing into the finished product collected in the downstream system. Additionally, wear on the rotor blades can increase the cut size, allowing coarse particles to pass through the rotor into the final product. Therefore, timely replacement of severely worn guide vanes, rotor blades, and labyrinth seal ring grooves is an effective way to prevent coarse particles from entering the finished product.
The emergence of increased water demand in the cement after replacing the relevant spare parts likely indicates insufficient precision in the replacement parts or changes in the design parameters. Specifically, the density, angle, and other parameters of the guide vanes and rotor blades may have been designed without adequate consideration of their impact on cement particle size distribution, thereby affecting the cement's performance in use. In such cases, cement producers are advised to contact the separator manufacturer to further optimize the density and angle of the guide vanes and rotor blades. This will help achieve a cement particle size distribution after classification that closely aligns with the ideal profile.
