" "Micro-sized coal has many applications in various industries with ball millequipment, which is one of the comminution methods for producing fine particles.This research aims to investigate the effect of variations in grinding balls andgrinding time on the comminution results of coal on a laboratory scale. The coalsamples were crushed with a jaw crusher with an opening of 1 cm. After collectingand dividing the samples, the product was used as feed in the grinding process. Thegrinding was performed by varying the diameter of the grinding balls and thegrinding time for 80 minutes. Particle size analysis was performed on the productat each 20-minute interval. The experimental results were then graphed todetermine the particle size distribution and to understand the impact of the grindingvariables on the P80 product. Based on this study, it can be shown that the P80value of the ground product sharply decreased to a size of 0.60 mm or 40 mesh,then leveled off, working at 96% of the critical speed, with a Cataractingmechanism and dominant impact fracture, then gradually decreased after 60 to 80minutes of grinding time. The study of milling processes with variations in ball milldiameter showed that the optimal rate of formation of fine particles, P80 = 0.63mm, was achieved with a variation in ball mill diameter of 40 mm with a 20-minutetime, then for finer particles, P80 = 0.38 mm, using a ball mill diameter of 20 mmwith a 20-minute time."