Abstarct: It is important to reach the particles to the right degree of Liberation in mineral processing plants, which is done by several stages of crushing and grinding. Ball mills are usually placed in the last stage of the comminution cicuit and play the most important role in this regard. The two main mechanisms of comminution in tumbling mills are impact and abrasion. In order to improve the performance of ball mils, it is necessary to make the role of the impact mechanism more prominent and the role of the abrasion mechanism less important. This is possible by creating the right shoulder and toe points and by finding the right distribution of ball combinations for the crushing load. The aim of the present study is to simulate and optimize the ball mils of the comminution circuits of the Sangan Khaf Tus Asphalt Processing Plant with LIGGGHTS software. Its crushing circuit consists of dry grinding (HPGR) and two parallel closed-circuit ball mils with a set of hydro cyclones. Regarding that ball mill plays a key role in the overall efficiency of the process, its simulation and optimization are of particular importance. The results showed that the maximum shoulder height was 478.75 cm, created by the distribution of 4, 6, 8 cm of balls, which compared to the shoulder height 461.79 cm created by the distribution of the 4 and 6 cm of balls, currently used in the ball mill of the Tus Asphalt Company was about 17.79 cm higher. Therefore, it is suggested that this new combination be used to improve the performance of the ball mill of this company instead of using the present combination. Also, grinding media energy of the ball mill of this copany mill was investigated and the effect of fifteen different size distributions of the combination of the 4, 6, 8, and 10 cm balls on grinding media energy (sum of kinetic and potential energies of all balls) in the ball mill of Sangan mine using discrete element method (DEM) has been investigated. The results showed that the lowest amount of energy transferred from the mill to the grinding media was related to the 4 cm distribution by amount of 1745.726 kJ. Also, the highest amounts of energy transferred from the mill to the grinding media were respectively related to the 10 cm distribution by amount of 6791.432 kJ and the 4, 6 and 10 cm distribution by amount of 6598.39 kJ and the distribution (4 and 6) cm by amount of 6576.04 kJ. As a result, instead of 4 and 6 cm balls that receive about 2830.546 kJ energy from the mill and are currently used in the Sangan mine, the (4, 6, 10) cm distribution can be used because of maximum load height and energy, and in this way the performance of the ball mil will be improved. Also, in order to investigate the effect of the type of balls, the optimal state simulation, i.e. the combination of 4, 6 and 10 cm balls for ceramic balls was performed. The results showed that ceramic balls, while produce a higher shoulder height, but will produce much less grinding media energy (3196.74 kJ) than steel balls (6598.397 kJ). Therefore, it is recommended to use steel balls in Sangan mine.