Coal obtained from the Catalagzi thermal power station was prepared into a -2360 +1700μm mono size fraction and ground for different times in a laboratory-scale stirred media mill. The breakage behavior was investigated and an attempt was made to determine optimum grinding conditions. Three stirring rates (1440, 720, and 360rpm) and three ball sizes (6, 4, 2.36mm) were utilized in the grinding studies. It was determined that for effective grinding not only the mill's mechanical properties but also the material properties have to be taken into consideration in order to determine breakage functions more accurately. At longer grind times, oversize material mainly composed of shale, which is comparatively difficult to grind. As a result of this, breakage rate slows down and a deviation from first-order breakage behavior occurs in the grinding stage. Copyright © Taylor & Francis Group, LLC.