Abstract: In a fluidized bed apparatus for separation of two mixed solid phases of which one is formed by a fluidizable powdery material and the other is formed by a material which is not fluidizable under the conditions of fluidization of the former, an enclosure is suspended by springs and formed by a lower casing portion (1) for a flow of gas and an upper casing portion (2) for a flow of fluidized powdery materials, between which there is disposed a porous fluidization wall (3), at least one conduit (4) for feeding gas to the lower casing portion (1) and at least one conduit (5) for discharging the fluidization gas from the upper casing portion (2). The upper casing (2) includes an inlet (6) for the regular introduction of the mixture of the two solid phases to be separated, an overflow (7) on a face of the enclosure for discharge of the fluidized solid phase, and an outlet for discharge of the settled solid phase.