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Frequent Kiln Coating Peeling Hard to Cure? Ruitai Custom Refractory Formula Achieves Perfect Match Between Coal Ash and Refractory Bricks
Time：
May 21,2026
1. Industry Pain Point: Unstable Kiln Coating Becomes Hidden Hazard in Cement Production
The stability of burning zone kiln coating directly affects kiln operation cycle, refractory consumption and production safety. Most manufacturers only adjust operational factors such as flame shape, coal fineness and raw material saturation ratio when facing frequent coating shedding, while ignoring the core cause — mismatched coal ash composition and refractory brick formula, resulting in recurring problems.
2. Core Principle of Coating Adhesion on Magnesia Bricks
Coating adhesion on commonly used magnesia-alumina spinel bricks and magnesia-iron spinel bricks relies on interfacial chemical bonding rather than simple physical adhesion. At high temperature, MgO on brick surface reacts with clinker liquid phase and oxides brought by coal combustion to form continuous and dense calcium-magnesium silicate and ferroaluminate transition layer, which acts as a stable bridge connecting bricks and kiln coating.
3. Three Mechanisms of Unstable Coating Caused by Mismatched Coal Ash
According to field failure analysis on multiple cement production lines, abnormal coal ash components mainly lead to coating instability in three ways:
(1)High silica-alumina coal ash: When total content of SiO₂ and Al₂O₃ exceeds 80%, liquid phase viscosity rises sharply, causing fast-growing loose and brittle coating prone to fracture.
(2)High iron and alkali coal ash: Excessive Fe₂O₃ or alkali content accelerates interfacial reaction and forms low-melting phases, greatly weakening bonding strength.
(3)Imbalanced sulfur-alkali ratio: Disproportionate SO₃ and alkali content generates expansive sulfate compounds, leading to coating bulging and massive shedding.
4. Ruitai Solution: Customized Magnesia-Iron Spinel Bricks
Supported by strong R&D capacity, Henan Ruitai develops high-purity customized magnesia-iron spinel bricks tailored to different coal ash characteristics:
●Precisely adjust content and distribution of FeAl₂O₄ to control reaction activity among bricks, coal ash and clinker liquid phase
●Form thin, compact and moderately strong interfacial transition layer, keeping stable coating thickness at 15-25mm
●Possess excellent slag erosion resistance and thermal shock stability to extend kiln service cycle
5. Industrial Application Effect
Ruitai customized magnesia-iron spinel bricks have been widely applied on domestic 5000t/d and larger cement production lines:
●Kiln coating peeling frequency reduced by more than 50%
●Refractory consumption in burning zone cut down by 20%
●Kiln continuous operation cycle prolonged by 3 to 4 months
6. Conclusion
Matching degree between coal ash composition and refractory formula is the key to stable kiln coating. Henan Ruitai provides one-to-one customized refractory solutions based on customers’ raw material and fuel features to fundamentally eliminate frequent coating shedding.
Please contact Henan Ruitai for professional technical consultation and on-site service.
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