1. Increase the auxiliary nozzle at the top of the tower.
Because the current ceramic factory mostly uses pressure type spray drying tower, the hot air enters the tower from the top, and the slurry is sprayed upward, resulting in a relatively high hot space at the top of the tower without droplets entering. In order to make full use of the heat source and increase the powder output, auxiliary nozzles can be added at the top of the tower.
2. Improve the air distribution structure and increase the evaporation intensity.
An air distributor is arranged at the air inlet, so that the hot air entering the tower gradually decreases in the radial direction from the central axis of the tower. In this way, the wind can be divided into several strands to rotate and enter the tower, or the wind can be divided into several strands to move downward in parallel. This improvement can improve the utilization rate of heat, and also make the moisture content of the powder uniform, thereby improving the quality of the powder.
3. Control the inlet and exhaust air temperature.
Increasing the inlet and exhaust air temperatures can effectively increase the output of powder. However, as the inlet air temperature increases, the bulk density of the powder will decrease. Generally, the inlet air temperature should be adjusted at 400-500°C; the exhaust air temperature should be stable to ensure that the moisture content of the powder is consistent. At the same time, the slurry feeding pressure and the number of spray guns also directly affect the moisture content of the powder.
4. Suitable ceramic additives.
As an auxiliary raw material for ceramic production, additives can make up for the defects that the raw materials themselves cannot overcome. For blanks with little or no clay content, it is difficult to form due to poor plasticity. Wetting agents and plasticizers must be added to form a liquid interlayer between the blank particles, thereby increasing its plasticity and reducing the internal friction between particles. , to ensure that the pressure distribution is uniform and the pressure loss is reduced when pressing the green body, and at the same time, the particle structure and properties of the powder are guaranteed. Commonly used additives are: triethylene glycol acetate, glycerol, cellulose derivatives, polysaccharides with high degree of polymerization, etc. The addition amount is between 0.2 and 1%, which has good effect.
5. Adjustment of particle gradation.
Adjust the powder particle size by adjusting the spray pressure and nozzle diameter. Generally, the pressure increases, the spray height increases, and the droplets become smaller; on the contrary, the spray height decreases, and the droplets become larger. When the nozzle aperture is reduced, the particles become smaller; when the nozzle hole is enlarged, the particles become larger. In production, it is usually required that the amount of large particles should be as high as about 50%, and the fine powder should be reduced as much as possible to ensure easy exhaust when pressing the green body, so as to reduce spalling defects, reduce the compression ratio, and improve fluidity.
6. Ensure that the fuel is fully burned, and adjust the ratio of fuel or gas to air volume.
Avoid fuel ashes falling into the powder, resulting in product foaming, color dirty and other quality problems. At the same time, the furnace temperature in the hot blast furnace is strictly controlled. Generally, it is required to generate a high temperature of at least 1000 °C, and the fluctuation range should be as small as possible.
7. Reasonable obsolescence period.
Staleness is used to ensure that the moisture content of the powder is uniform. At the same time, a large number of anaerobic bacteria multiply in the billet, and in the low temperature and high humidity environment, they continue to die and become humic acid, which improves the plasticity of the billet. Generally, the stale period of the powder is 24-48/hour.
There are many factors that affect the milling efficiency and powder quality, some of which are interrelated and restricted, and the process should be adjusted or diligently advanced according to the actual production situation, so as to improve the production efficiency.
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