Using a discrete element method (DEM) software, this paper develops a methodology to obtain the forces acting on each face of the lifters and on the liner plates of a grinding mill and it correlation to the mill torque and power. This analysis gives a clear view of the contribution of each lifter face to the torque and power. A pilot mill with a transparent cover charged with steel and aluminum balls is simulated in DEM, obtaining the forces in the lifters faces and the resulting torque and power. This power is compared to the power released by the DEM software and the power obtained from the strain gauge. Results show an almost perfect matching between the power from the lifters forces and the DEM power, and a small error compared to the measured torque and power. The analysis of the shape, magnitude and position of force pulses acting on the front and back faces of the lifters for different mill filling and speed is correlated to the power curves and gives a physical explanation of the shape and variations of the power.