Cement Manufacturers Association (CMA)

6 Coating Stability and Refractory Life: Practical Levers for Fuel Savings, Kiln Reliability and Decarbonisation in Cement Plants Dr S B Hegde Professor, Department of Civil Engineering, Jain College of Engineering and Technology, Hubli, India and Visiting Professor, Pennsylvania State University, USA 01 Abstract Coating stability and refractory performance in rotary cement kilns are frequently treated as routine maintenance topics. In practice, they form core process and control challenges that directly affect thermal efficiency, fuel costs, kiln up time and emission levels. Kiln shell heat losses typically range from 8–12% of total thermal input, with overall process energy dissipation linked to unstable coatings and suboptimal refractories reaching up to 11.3%. Unstable coatings—aggravated by alternative fuels such as refuse-derived fuel (RDF), biomass and tyres—cause periodic collapses that spike fuel demand, generate CO and accelerate refractory wear. Global thermal modelling shows that a stable 20–50 mm coating layer can cut shell heat losses by about 53%. Advanced refractories with better insulation reduce losses by an additional 18–24%. In India, where the average thermal substitution rate (TSR) is around 7% (versus 30–40% in leading European plants), variable alternative-fuel chemistry often triggers coating instability. This shortens burning-zone refractory life to 9–12 months and increases specific fuel consumption by 20–80 kcal/kg clinker. This article combines hands-on operational insights with global research (2020–2026), AI- driven monitoring data and economic analysis. It quantifies savings potential (USD 0.38–3.5 million annually for a 5,000 TPD kiln), typical payback periods (6–18 months) and India-specific barriers under the NITI Aayog Cement Sector Decarbonization Roadmap (2026), which targets 20% TSR by 2030 via RDF scaling and projects cumulative emission reductions of approximately 80 MtCO e (about 10% lower energy-related 2 emissions vs. business-as-usual).