Mulugeta Sisay (PhD)Wubsera Gebrekidan2025-10-012025-10-012025-08https://etd.aau.edu.et/handle/123456789/7456This study examines the effect of grinding media shape on ball mill efficiency by comparing spherical balls to worn, non-spherical balls in the grinding of limestone ore, an essential but energy-intensive process in which media consumption accounts for approximately 37% of operational expenses. To fill a significant research gap in media shape degradation, the methodology used controlled laboratory-scale batch grinding tests under identical conditions, with the resulting products analyzed through sieve analysis to determine particle size distribution (P80), and specific energy consumption and power draw were calculated using established comminution theory. The results demonstrated a clear and significant effect, showing that spherical balls produced a finer product (P80 of 80.72 μm) compared to worn balls (P80 of 86.46 μm), while also achieving this superior result with lower energy consumption (16.31 kWh/ton vs. 17.84 kWh/ton) and a reduced power draw (2.61 kW vs. 2.85 kW), indicating that worn balls lead to less efficient grinding and higher operational expenses due to their irregular shape and reduced effective surface area. Consequently, the study confirms that maintaining spherical grinding media is crucial for optimizing mill efficiency and profitability, recommending that industrial operations implement regular media monitoring and replacement schedules, while suggesting future research explore mixed media charges and interactions with other variables like mill speed and liner profile for a more comprehensive understanding.en-USGrinding mediaspherical and worn ballslimestonegrinding test.Thesis