Patent ID: 7237679

Claim:
A process for separating particles of the same material comprising particles of different sizes comprising: projecting in a first direction a stream of particles into a fluid medium, the first direction of the particles as they are projected being against a direction of flow of the fluid medium; allowing said particles to develop differing trajectories in said fluid medium; providing at least two separate collection areas for different average size particles from said stream of particles; smaller particles moving smaller distances to a near collection area and moving larger particles moving longer distances to a farther collection area of the at least two collection areas; and collecting particles along said different trajectories in said at least two separate collection areas; wherein said fluid medium has a vector component that is negative with respect to the stream of particles when projected into the fluid medium and the fluid component has a vector that is between −1 and −45 degrees with respect to the stream of particles when it is projected into the fluid medium.