Apparatus (10) for the concentration and beneficiation of particulate matter by froth flotation employs a constriction plate (14) which separates verti­cally arranged flotation (17) and hydraulic (18) com­partments. A discharge duct (29) may be used to extend through the hydraulic compartment (18) and to open through the constriction plate (14) centrally thereof. Orifices (16) in the constriction plate (14) are in communication with the hydraulic compartment (18) to provide a uniform dispersion of air bubbles in the flotation compartment (17). Aerated water distribution manifolds (22, 42) within the hydraulic compartment (18) and within the lower portion of the flotation compart­ment (17) are provided to enter the aerated water into the flotation compartment substantially uniformly throughout a horizontal cross-section thereof. In order to minimize the energy consumption of the apparatus (10) and to provide for the introduction of aerated water at a reduced flow rate, amenable to the separation of aqueous pulps having a low concentration of solid matter by volume, such as sulfides, a stream of pressurized air is passed through an eductor (53) wherein a mixture of water and, if desired, an appropriate surfactant is aspirated into the stream of flowing pressurized air. The flowing stream of pressurized air and the aspirated water and surfactant are then passed through a venturi region (59), producing a highly aerated, low water volume stream of aerated water for delivery to the hydraulic compartment (18).