By means of computational fluid dynamics simulation technology, the particle flow behavior in a XFD flotation machine was simulated with Euler's method, and the effects of impeller speed and particle size on the distribution characteristics in a solid-liquid two-phase flow field were explored to reveal fluid motion behavior in the flotation machine. The flotation kinetics of the flotation machine was also explored in terms of velocity field and turbulence intensity. The simulation results show that with a rotating speed at 1 800 r/min, the liquid-phase flow moves at a maximum speed of 5.32 m/s, and the fluid motion velocity and kinetic energy of turbulent are higher in the rotor zone and the lower circulation zone. The flow field is relatively stable, which is suitable for mineral flotation separation. The particle size of fine-grained minerals has a minor influence on the solid-liquid two-phase flow characteristics in the flotation machine, and the pressure distribution of the rotor surface is closely related to the particle size. It is found that the kinetic energy of turbulent is significantly enhanced in the region between the stator and rotor, which can effectively promote the dispersion of hematite particles. In a hematite flotation test, the variation in concentrate grade and recovery obtained with different rotation speed of impellers was studied. It is shown that with impeller rotating at a speed of 1 800 r/min, an iron concentrate with Fe grade of 66.35% and recovery of 85.34% can be produced. Based on the simulation of flow field of flotation machine, it is concluded that an impeller with a rotating speed of 1 800 r/m is suitable for flotation operation.