Numerical simulations of a slurry bubble column with particle loadings up to 40 vol % and superficial gas velocities up to 0.26 m/s have been performed using the Euler-Euler approach with the renormalized group (RNG) k-epsilon turbulence model. Special attention was paid to the bubble size distributions, interphase closure models, and liquid-solid drag forces. A modified Luo-Lehr population balance model was used to simulate the changes of mean bubble size and the overall gas holdup as functions of particle loadings. A pseudo gas-slurry closure model was proposed to overcome the drawbacks of existing interphase momentum exchange closure models. The newly constructed model was different from the traditional gas-slurry closure model in that the hydrodynamics of three phases are solved by three sets of momentum equations describing gas, liquid, and solid phases, respectively. Three different drag force models, i.e., the Schiller-Naumann model, the Wen-Yu model, and the energy-minimization multiscale (EM.MS) model, were used for the computation of the liquid solid interaction force and the simulated particle settlings were compared with experiments. A series of numerical simulations were performed. The following conclusions were drawn from the simulation results: (1) The Luo-Lehr population balance model could simulate the mean bubble size changes as a function of particle loadings. The gas holdup and its variation trend predicted by the modified Luo-Lehr population balance model were in agreement with the experimental data by setting a coalescence coefficient C-0 = 0.4. (2) A pseudo gas-slurry closure model that took the influence of solid concentration into account was recommended for gas-liquid-solid three-phase simulation when the particle size was much smaller than the bubble size. The simulated average gas holdups showed good agreement with the experimental data. (3) The axial distribution of solid concentration simulated by the EMMS drag model was much closer to experimental results than other drag models for the simulation of slurry bubble columns.