Sedimentation or settling involves allowing the heavy phase to fall through the light phase and collect on an imperforate surface and typically involves fine solids with long settling times. Examples are decanters, and disk nozzle centrifuges. On the other hand, filtration depends on the particle size being large enough to build a cake on a filter cloth or a screen. The cake must also be porous enough to allow mother liquor to flow through it.
Examples are pusher, peeler, and vibrating screen centrifuges.
Various types of centrifuge are manufactured, and each type of centrifuge has certain advantages over a specific range of process variables. Figure 1 shows the range of variables where the pusher centrifuge is generally used. For most applications, these particles are crystalline in nature, but non-crystalline materials have been successfully dewatered on the pusher centrifuge. These particles must be distinct, free draining and the liquid must not be chemically attached to the solids, i.e., waters of hydration. As seen in Figure 2, the slurry is fed through a stationary feed pipe at the centerline of the pusher basket.