Rotary kilns are the heart of cement, lime, and metallurgy facilities. Selection of refractories for these kilns requires engineering expertise.
Rotary Kiln Zones
1. Drying Zone
This is the entry zone of raw material. Temperatures are relatively low (below 800°C). Abrasion resistance is important here.
2. Calcination Zone
Where carbonates decompose. Temperatures rise to 1000-1100°C. Alkali attack becomes significant.
3. Burning (Sintering) Zone
The hottest zone (1450°C+). Magnesia-spinel or dolomite bricks are essential here to withstand extreme heat and coating formation.
4. Cooling Zone
The discharge thermal shock area. Needs materials that can handle rapid temperature changes.
Selection Criteria
- Chemical Composition: Compatibility with process material
- Porosity: Low porosity resists chemical attack
- Strength: To withstand mechanical rotation loads