Abstract Particle entrainment is a serious problem in spouted bed contactors when operation is carried out using beds made up of ultrafine particles, irregular ones and fine and coarse particle mixtures. Accordingly, the conventional conical spouted bed has been modified by inserting a fountain confiner in the contactor, and a study has been carried out on the efficiency of the confinement device to avoid fine particle entrainment. Furthermore, the influence of the geometry of the device on the hydrodynamics of conical spouted beds has been studied. The results show that the fountain confiner largely avoids fine particle entrainment, i.e., 60–70% reduction depending on the type of draft tube used. Furthermore, the fountain confiner reduces the operating bed pressure drop and the maximum cycle time of the particles in the contactor, but has no effect on the minimum spouting velocity. Nevertheless, the greatest advantage of the fountain confiner lies in the stabilization of the fountain and the homogenisation of the solid circulation in the bed, which leads to a significant increase in the gas-solid contact in the fountain.