A device for conditioning particulate matter such as particalized soybean meats and hulls. The device includes a chamber. The chamber includes a lower increased velocity stage in which gas movement is accelerated because of constriction resulting from the interposition of a plurality of staves. The lower increased velocity stage is disposed beneath a normal velocity stage which is coextensive with a discontinuity in a side wall of the chamber through which particulate matter is introduced. Gas flow is introduced into the chamber proximate the bottom end thereof and is directed upwardly in a direction opposite that in which particulate matter passes downwardly under the influence of gravity. The velocity of the gas through the normal velocity stage is regulated so that heavier particulate materials will pass downwardly and lighter materials will pass upwardly. Velocity is maintained at a level through the lower increased velocity stage so that downward passage of the heavier particulate materials will still be permitted. As those materials pass downwardly, grains would ricochet off the various staves in order to facilitate further separation in an application wherein the particulate materials comprise fragments, for example, of soybean meats and hulls.