We perform Eulerian-Lagrangian simulations of solid-liquid flow in a mixing tank. The simulations are three-dimensional and time dependent and in the transitional flow regime. The lattice-Boltzmann method is used to solve the volume-averaged Navier-Stokes equations. The overall solids volume fraction is of the order of 10%. Situations with the solids only partly suspended are compared to those with fully suspended solids. The emphasis is on the effect of the particle size distribution (PSD) on the suspension behavior. Four PSD's all having the same d(32) were investigated. It is harder to fully suspend particles with wider size distribution as compared to narrow distributions. (C) 2018 Elsevier Ltd. All rights reserved.