A process and device for separating different types of particulates from a mixture, which is especially suited for separating unburned carbon from raw fly ash. The process entails separating raw fly ash by size into a fine component and a coarse component (the coarse component having typically higher levels of unburned carbon). The coarse, high carbon, fly ash component (or optionally both components) are processed through an inclined fluidized bed to produce an upgraded coarse component with reduced unburned carbon. An acoustic field is imposed on the inclined fluidized bed(s) in order to enhance the bed's ability to fluidize and segregate the unburned carbon. The upgraded coarse and fine components are then mixed to yield a final product.