As a large-scale important raw material of refractory materials, tabular corundum is produced by using a high-temperature shaft kiln to produce sintered tabular corundum, which is characterized by the following process steps.
1. Ball milling. Using Bayer process light-burned alumina powder as the raw material for continuous ball milling, the fineness and specific surface area must meet the requirements, which will help the sintering and densification of the alumina powder.
2. Into the ball. The ground powder is made into a ball using a ball disk or a ball tube. The formed pellets must have strength to avoid breakage during transport to the dryer. In the process of pelletizing, the semi-finished pellets have high water content, easy layering, and difficult drying problems. The corresponding process optimization design is carried out and properly solved.
3. Dry. The formed green balls are put into the dryer. The countercurrent hot air in the shaft kiln is used for drying to remove about 15% (w) of moisture. However, the temperature in the shaft kiln must be strictly controlled to avoid cracks and stratification, or even agglomeration and blockage in the billet, which will cause the interruption of the ball flow and the deterioration of the drying quality.
4. Sintering. The green balls enter the shaft kiln after drying. The sintering temperature is 1900`1950°C. By controlling the temperature and flow rate of the hot air in the shaft kiln, a plate-like corundum structure with fully developed and sintered crystals is obtained.
After sintering, after cooling, sorting, inspection, crushing and screening, products of different particle sizes can be obtained.
