A cyclone is a device that uses fluid pressure to generate rotational motion. When the slurry enters the cyclone at a certain speed, it is forced to rotate after encountering the wall of the cyclone. Due to the different centrifugal forces, the solid coarse particles in the slurry are subjected to a large centrifugal force, which can overcome the hydraulic resistance and move towards the wall of the instrument. Under the combined action of its own gravity, it spirals downward along the instrument wall. The fine and small particles and most of the water rotate with the slurry before they get close to the wall of the instrument. Under the subsequent feeding, the slurry continues to move downward and slew, so the coarse particles continue to concentrate to the surrounding area, while the fine particles stay in the central area, and the particle size becomes larger and larger from the center to the wall, forming a layered arrangement.

As the slurry flows from the column part of the cyclone to the cone part, the flow section becomes smaller and smaller. Under the shrinkage and compression of the outer slurry, the inner slurry containing a large number of fine particles has to change the surface direction and move upward to form an internal cyclone, which is discharged from the overflow pipe and becomes overflow, while the coarse particles continue to spiral downward along the wall of the vessel to form an external cyclone, and finally discharged from the bottom flow port to become sand sinking.