Abstract: Fractionation apparatus (20) is disclosed which utilizes a rapidly rotating disk which receives a liquid suspension of particles to be separated onto its rotating face surface (35). When the film of liquid and particles on the rotating face surface (35) reaches the peripheral edge (38) of the face, particles having sufficient kinetic energy to overcome surface forces (e.g., above a certain size) are radially ejected while particles with less kinetic energy (e.g., smaller particles) and the liquid are carried over the edge onto the surface of a depending rim (39). The suspension of smaller particles and liquid is carried down the rim to the rim edge (40) at which point the smaller particles and liquid are disengaged. A separator wall (27) may be interposed between the two streams of particles emanating from the disk (24) to provide a physical separation of the larger and smaller particles once they have left the disk.

Abstract: Fractionation apparatus utilizes a rapidly rotating disk which receives a suspension of particles to be separated in a liquid. The rotating disk has a planar floor onto which the particle containing liquid is supplied. The floor is joined to an inclined inner wall in a smooth curve. An axially symmetric trip, located between the inner wall and an outwardly extending, preferably upwardly inclined skirt, maintains particles in the film away from the surface of the disk and results in more efficient ejection of large particles from the liquid. Smaller particles are ejected from the disk along the rim which descends from the skirt or from the edge at which the skirt joins the rim. The characteristics of the disk surface, the disk speed, the size and number of trips, the suspension feed rate, and other operating conditions can be selected such that highly efficient fractionations of particle suspensions, such as wood pulp slurries, can be obtained.

Abstract: Fractionation apparatus (20) is disclosed which utilizes a rapidily rotating disk which receives a liquid suspension of particles to be separated onto its rotating face surface (35). When the film of liquid and particles on the rotating face surface (35) reaches the peripheral edge (38) of the face, particles above a certain size are radially ejected while smaller particles and the liquid are carried over the edge onto the surface of a depending rim (39). The suspension of smaller particles and liquid is carried down the rim to the rim edge (40) at which point the smaller particles and liquid are disengaged. A separator wall (27) may be interposed between the two streams of particles emanating from the disk (24) to provide a physical separation of the larger and smaller particles once they have left the disk.