Method and apparatus for separation of heavy and light particles from particulate material

Apparatus for the separation of heavy and light particles from fibrous particulate material which includes means for continuously fluidizing and agitating the fibrous particulate material to cause heavy particles to sink from the light particles comprising a deck adapted to receive material at a reception end thereof, means for vibrating said deck thereby causing the material to move longitudinally along said deck to a discharge end thereof;

• said deck having a number of longitudinally extending troughs each defined by an upper trough portion, a lower trough portion and a bottom;
• means for supplying pressurized air to each trough to cause an upwardly directed air flow therein in a direction from each bottom upwardly to each upper trough portion,
• (a) means for creating a first air velocity at a first upper separation zone in each said upper trough portion which causes separation of the heavy and light particles by lifting the light particles and allowing the heavy particles to fall through the first upper separation zone into a second lower separation zone, and
• (b) means for creating a second air velocity at the second lower separation zone in each said lower trough portion which gradually increases in velocity toward the first upper separation zone to cause a second separation of heavy and light particles in the second lower separation zone by lifting at least some of the light particles back into the first upper separation zone and allowing the heavy particles to fall down toward the bottom of each lower trough portion into a region of still lower air velocity.