Development of Maintenance Management Model for Reducing Power Consumption for Grinding Mills and Kilns in the Cement Industry: A Case of Kisarawe Cement Plant – Tanzania

Abstract

This study developed a comprehensive maintenance management model aimed at reducing power consumption in grinding mills and kilns within the cement industry, using Kisarawe Cement Plant in Tanzania as a case study. The research addresses the critical issue of excessive energy consumption in cement manufacturing, where grinding and kiln operations account for approximately 70-80% of total electrical energy usage, significantly impacting production costs and environmental sustainability (Madlool et al., 2011; World Business Council for Sustainable Development, 2022). The study employed a quantitative case study approach, combining field data collection, analysis of equipment performance records, and expert interviews with maintenance personnel. Statistical analysis, utilising the Relative Importance Index (RII) methodology, was applied to identify and rank maintenance factors affecting power consumption (Kumar et al., 2022). Multiple regression analysis was employed to develop predictive relationships between maintenance practices and energy efficiency (Vincent et al., 2024). Data was collected from 101 equipment records across multiple operational periods, with comprehensive validation conducted over a 12-month timeframe. The analysis revealed twelve critical maintenance-related factors, with six achieving very high priority status (RII > 0.9), including kiln coating/ring formation issues (RII = 0.927), fan/blower impeller fouling (RII = 0.921), and worn grinding media in ball mills (RII = 0.921). A statistically robust mathematical model was developed with exceptional predictive capability (R² = 0.99), incorporating seven key maintenance factors: worn grinding media, misaligned mill drives, motor bearing deterioration, poor lubrication systems, kiln coating issues, fan impeller fouling, and kiln refractory degradation (Nakajima, 1988; Moubray, 2001). The model equation: Power Reduction (%) = 0.11 + 0.032×WGM + 0.05×MMD + 0.05×MBD + 0.03×PLS + 0.025×KCR + 0.011×FBF - 0.06×KRD demonstrates that targeted maintenance interventions can achieve significant energy savings. Validation results showed remarkable accuracy with 98% predicted versus 98% actual availability performance, confirming the model's practical applicability in industrial settings (Law et al., 2007). Implementation of the proposed maintenance management model led to measurable improvements in energy efficiency, reduced operational costs, and extended equipment lifecycles. The research contributes to both academic knowledge and industrial practice by providing cement manufacturers with a scientifically validated, quantitative framework for implementing energy-focused maintenance strategies that address root causes of power inefficiency while maintaining operational reliability and production quality standards.