Star unloader is also known as unloader, rotary feeder, air lock valve. Usually the structure of star unloader is composed of rotor impeller with several blades, shell, sealing parts, reducer, motor and so on. When the material in the upper silo is filled in the gap between the blades by falling weight, it is discharged from the upper part with the rotation of the blades. Therefore, the star unloader can discharge the material quantitatively and continuously.