For constructional as well as production-related reasons, the rotary kiln is subjected to a wide range of thermal, chemical, and mechanical influences.

Particularly the increasing use of alternative fuels leads to extremely high thermochemical and thermomechanical stresses in the refractory lining. Based on the material flow, a rotary kiln is usually divided into the following zones:

1. Kiln inlet cone‎

2. Preheating zone‎

3. Calcining zone‎

4. Upper transition zone‎

5. Combustion zone‎

6. Lower transition zone

7. Discharge area‎