Refractory lining for rotary kilns: what matters during the overhaul

Rotating kilns are among the most demanding units in refractory construction. Mechanical flexing, high temperatures and chemical attack hit the lining all at once. From more than 500 projects we have learned what matters.

Five factors in a rotary kiln overhaul

• Zone-specific material selection: the sintering, transition and discharge zones are considered separately — basic magnesia-spinel grades in the burning zone, more robust alumina bricks at the inlet and outlet.
• Shell survey before lining: an ovality of more than 0.3–0.5 % causes whole brick rings to fail. We check the geometry before any bricking starts.
• Clean ring construction: keying, gap dimensions and expansion joints determine the campaign life — often the difference between 12 and 24 months.
• Controlled heat-up curve: defined temperature ramps and holding stages protect a freshly installed lining against spalling.
• Condition monitoring during operation: shell thermography detects areas that have become thin at an early stage and enables targeted partial repairs.