Bogale Tadasse (PhD)Yonas Hordofa2024-05-022024-05-022023-09https://etd.aau.edu.et/handle/123456789/2960The purpose of this study was to investigate the impact of mill speed and grinding time on the grindability and comminution of gold ores from the Lega Dembi and Sakaro deposits. A batch mill internal diameter of 200 mm and volume (5 dm3) was used for the experiment. The study employed a two-factor approach, considering different grinding times (10 and 15 minutes) and three fractions of mill critical speed (40%, 50%, and 60%).The experiment involved dividing the feed into five equal portions across eleven size class fractions ranging from 4mm to -75μm, with a √2-series interval. A total of ten kilograms of material, divided into one-kilogram portions, were used for the experiment. The objective of maintaining a critical speed below or equal to 50% was to minimize energy consumption during the milling process. The study aimed to assess both the grindability and energy consumption of the two deposits. The results of the study indicated that the rate of breakage increased with grinding time rather than mill speed. For the Lega Dembi deposit, at 40%, 50%, 60% speed and 15 minutes grinding time, the amounts of desired particle size classes produced were 251.7 grams, 264 grams, and 263 grams for the different mill speeds. Similarly, for the Sakaro deposit, the amounts produced were 251.7 grams, 232.6 grams, and 256 grams for the respective mill speeds. Based on the obtained results, the study concluded that mill speed had no significant effect on the grindability of the gold ores from both mining sites, as grinding times.en-USMill speedgrinding timegrindabilitycomminutionenergy consumptionmill critical speedgold ore.Thesis