Patent ID: 7564023

Claim:
A sorting method including the steps of: forming an at least part annular, substantially monolayer flow of particulate material by axially flowing said particulate material over a dispersion member having a substantially conical flow surface bounded by an axially perpendicular peripheral edge whereby product flow is directed onto substantially the whole conical flow surface in a monolayer and over said edge to pass through a collimator comprising opposed inner and outer guides in a nested, coaxial, opposed and frusto conical, arrangement to form an annular, vertical, concentric monolayer product flow; operating a detector having an optical element located substantially centered within said annular flow downstream of said collimator whereby the path length from all parts of the flow passing between the collimator and the optical element is substantially constant, as a consequence of the collimated and monolayered flow, said detector being selected to apply a sorting criterion on the particles in said flow; and operating a sorting means responsive to said detector to sort particles in said flow according to said criterion.