A new hybrid approach to model powder mixing based on the use of discrete element method (DEM) and compartment modeling is presented. The main motivation behind the proposed approach is to reduce the computational expense of modeling powder mixing by partitioning the mixing system into high shear areas that are modeled using detailed DEM simulations, whereas the remaining process is simulated using stochastic models. The approach can, thus, be used to model complex geometries, as well as a large number of particles that is typically unfeasible with the existing approaches. The results of a horizontal convective mixing vessel are used to illustrate the applicability and efficiency of the proposed approach. (c) 2006 American Institute of Chemical Engineers AlChE J, 53: 119-128,2007.