- A combined discrete element method (DEM) and CFD numerical model was developed to simulate particle comminution in a jet mill. The DEM was used to simulate the motion of the particles in the gas flow. For this, the compressible Reynolds Averaged Navier-Stokes (RANS) equations were used to describe the gas flow field inside a given size's jet mill. Ghadiri's models for breakage and chipping were implemented in the simulation to define the reduction of the particle's size during jet milling. The size distributions of the particles after grinding were obtained numerically. The prediction of the numerical simulation for the median particle size d 50 after grinding was qualitative compared with experimental results for the different operating conditions (i.e., feed rate, angle of grinding nozzles, volumetric rate of grinding air, etc.). The comparison shows good agreement with the experimental observation. The results shows that the feed rate, angle of feeding nozzle, and feeding air's flow rate have more influence on the breakage and chipping of particles in jet milling. In addition, a parametric study was performed to obtain the desired operation conditions.