Abstract This work evaluates the performance of commercial hydrocyclone for removing contaminant larger particles (silt fraction) in bentonite clays, which improves its commercial value. A steady-state Eulerian–Eulerian 14-phases CFD model was verified with experimental data. The model was further used to simulate the effect of geometry and operational conditions on the recovery efficiency of fine clay fraction in the overflow. Simulation results provided data on the global fine recovery efficiency and granulometric distribution in the hydrocyclone overflow. An empirical correlation to calculate the clay volume fraction as a function of the hydrocyclone pressure drop as well as the characteristic constant parameter of the hydrocyclone family were obtained. Finally, a scale-up study was performed and the effectiveness of scaled up industrial hydrocyclones was obtained.