Ball mills are widely used in the industry for a large set of application as: grinding, breakage, mixing, among others. Applications in which the main objective is changing the particle size distribution of the material (i.e. particle breakage), depend on the mechanical events that the particles are subjected to. Mechanical properties in granular materials under dynamic conditions are difficult to measure experimentally. Simulation tools present limitations and challenges in these cases. However, by choosing the adequate model and the correct parameters, results provide insights into the interactions between powder, grinding balls and drum walls at the particle and contact scale. By means of 2D simulations using a DEM method known as Contact Dynamics and applying the bonded cell method (BCM) [1] for modelling breakable particles, simulations on the grinding of a powder inside a ball mill were performed. Samples with different grinding media size and quantity were tested in order to study the particle fragmentation modes that take place inside the system. Also, we determined the spatial distribution of the breakage events, and measured evolution of powder properties such as: damage degree, specific surface and particle size distribution.