Abstract: An air classifier to separate solids by air classification while eliminating emissions. The air classifier includes an in-feed delivery mechanism, such as a continuous conveyer belt in order to deliver solids to an input chamber. A hanging curtain is movable in response to solids entering the input chamber. A balanced gate moves in response to solids exiting from the input chamber. An air fan delivers forced air to an air classifier chamber which is in communication with the input chamber. A heavy fraction discharge is in communication with the air classifier chamber to receive a portion of the solids heavier than the force of air delivered to the air classifier chamber. A light fraction discharge in communication with the air classifier chamber removes light solids. A return air duct in communication with the light fraction discharge returns air from the light fraction discharge to the fan. A bleed-off duct delivers a portion of forced air from the fan back into the input chamber.

Abstract: An adjustable orifice trommel having an elongated body rotatable about an axis, an entry for insertion of particulate material, and an exit for retrieving screened material. The trommel includes a plurality of flat inner plates, each inner plate having a plurality of openings. An outer plate is provided for each inner plate slidable axially in relation to the inner plate, each outer plate having a plurality of openings matable with the inner plate openings so that moving the outer plate with respect to the inner plate will vary the size of the orifices.