Solid-liquid suspensions are commonly encountered in industrial production processes. The dynamics of the solid-liquid suspension behaviors depends on both liquid-particle and particle-particle interactions. In this work, an Eulerian-Eulerian model is used to characterize the suspension dynamics and the role of particle-particle interactions in solid-liquid mixing vessels is studied. The collision and friction of coarse particles are considered by calculating solid pressure and viscosity based on a modified kinetic theory of granular flow (KTGF). The solid phase holdup and the velocity are predicted and compared with semiempirical models. Effects of several key model parameters are investigated as well. The comparison between computational fluid dynamics simulations and experimental data shows a satisfactory agreement, which validates the robustness of the multi-fluid model. The proposed model is then applied to study the influences of particle size and solid loading for exploring the importance of particle-particle interactions. The obtained simulation results show that particle-particle interactions can influence suspension characteristics in the case of large particle size and high solid loading. (C) 2017 Elsevier Ltd. All rights reserved.