During the operation of the corn concentrator, the materials enter the screen body from the feed pipe, so that the materials are evenly distributed along the width of the screen. The large impurities fall on the large impurities sieve, and are discharged from the grain picker on the day of large collection. The grains fall on the small impurities sieve to be fully selected. The sifted materials are small impurities and barnyard grass. The sundries are discharged from the machine on a small day, and the material on the screen is clean grain, which enters the stone removing screen from the guide pipe. Under the comprehensive effect of vertical air flow from top to bottom and screen body directional motion, active classification is carried out. Sand and stone with large specific gravity sink to the bottom and touch the screen, while grains with small specific gravity and rough surface float to the top and are suspended. The light dust and rice husk are sucked away, and the grain on the upper layer slides slightly under the effect of its own gravity and the directional motion of the sieve. From the discharging day, the sand and gravel only sticking to the screen will jump up to the viewing area.

　　The grains mixed in the sand and gravel are blown back to the separation zone under the effect of reverse airflow, while the sand and gravel are discharged from the machine on the day of exit. The above is the operation process of the small picker. Secondly, let's take a look at the classification of grain pickers. There are many varieties of corn sorters. According to the cleaning principle, it can be divided into conventional cleaning method and electric separation method. Conventional cleaning method uses physical and mechanical characteristics such as several scales, aerodynamic characteristics and specific gravity of seeds for cleaning. There are more than ten kinds and dozens of methods, such as wind selection, selection, wind selection, air screen hole selection, specific gravity selection, hole selection, air screen specific gravity combination selection, photoelectric selection, zigzag plate selection and spiral separator.