Method for threshing and pneumatic separation of tobacco leaves

A method for threshing and pneumatic separation of tobacco leaves, the method comprising:

• 1) transferring heated and humidified tobacco leaves after a secondary conditioning process into a silo feeder via a feeding belt conveyor and a scraper feeder for balancing a feeding flow;
• evenly distributing the tobacco leaves by a proportion distributor into each threshing machine of a primary threshing set so as to rip tobacco slices and stems;
• transporting a mixture of the tobacco slices and the stems coming out of the primary threshing set into each branch of a primary pneumatic separation unit respectively;
• transporting qualified tobacco slices separated by the branches of the primary pneumatic separation unit onto a slice collection belt conveyor;
• and transporting a remaining mixture into a secondary threshing set;
• 2) collecting and transporting the mixture of tobacco slices and the stems coming out of the secondary threshing set into each branch of a secondary pneumatic separation unit;
• transporting the qualified tobacco slices and the qualified tobacco stems separated by the branches of the secondary pneumatic separation unit onto the slice collection belt conveyor and a stem-collected belt conveyor, respectively, and transferring a remaining mixture to a tertiary threshing set;
• 3) collecting and transporting the mixture of the tobacco slices and the stems coming out of the tertiary threshing set into a branch of a tertiary pneumatic separation unit;
• transporting the qualified tobacco slices and the qualified tobacco stems separated by the branch of the tertiary pneumatic separation unit onto the slice collection belt conveyor and the stem-collected belt conveyor, respectively, and transferring a remaining mixture into a quaternary threshing set;
• and
• 4) transporting the mixture of the tobacco slices and the stems coming out of the quaternary threshing set to a branch of a quaternary pneumatic separation unit;
• transferring the qualified tobacco slices and the qualified tobacco stems separated by the branch of the quaternary pneumatic separation unit onto the slice collection belt conveyor and the stem-collected belt conveyor, respectively, and returning a remaining mixture from the quaternary pneumatic separation unit to the quaternary threshing set;
• wherein
• the primary pneumatic separation unit is provided with air pressure type binary silos pneumatic separators for sorting out the qualified tobacco slices;
• and
• the secondary pneumatic separation unit, the tertiary pneumatic separation unit, and the quaternary pneumatic separation unit are provided with air pressure type triple silos pneumatic separators for sorting out the qualified tobacco slice and the qualified tobacco stems.