Mineral cleaning by machines that utilize air currents as the primary separating medium. The air machines can generally be divided into three types: (1) pneumatic jigs, in which the air current is pulsated; (2) pneumatic tables, in which the refuse is diverted from the direction of flow of the clean mineral by a system of riffles fixed to the deck; and (3) pneumatic launders, in which the products are flowing in the same direction, and the clean mineral is skimmed off the top of the bed and/or the refuse is extracted from the bottom in successive stages.