Abstract: This invention generally provides a process and apparatus for the separation of material and more particularly, the separation of material(s) using a separation fluid and based upon the relative buoyancies of the components of the material solution. This invention more particularly provides an apparatus and a process in which the feedstock is first introduced into a separation hopper wherein partial separation occurs by the less buoyant solid particles contained in the feedstock descending to and entering a separation chamber. The separation fluid flowing upwardly in the separation chamber is adaptable to match the settling velocity of the desired solid particle separation.