Abstract: An air classifier for the separation of refuse by density into homogeneous fractions. A waste bin discharges non-homogeneous waste which is dispersed within a mixing chamber whereat a pressurized airflow, moving upwardly therethrough, carries lighter particles upwardly into a main duct structure. Subjacent the mixing chamber, is a crossflow zone through which a secondary airflow moves transversely to waste gravitating from the mixing chamber. The classifier air duct is of irregular shape having enlarged portions, spaced therealong, each constituting a waste separating station whereat waste of like density gravitates into a discharge chute associated with the station. Air inlet means at each station directs a crossflow of air onto the gravitating waste matter to remove lighter density particles comingled therewith and reentrain same in the main duct airflow.