Abstract: A centrifugal separator for separating two components of a dry mixture has an annular surface inclined upwardly outwards and having a vertical axis of symmetry and a drive mechanism for rotating the surface around the vertical axis of symmetry. A centrally located feed mechanism feeds the mixture onto the surface. At least a first part of the surface is configured such that particles of one component are retained on the surface while particles of the other component progress upwards across the surface and over the upper edge. The separation process may be based on ridges or barriers which prevent upward movement of small particles, or on frictional differentials between types or shapes of particles. Multiple concentric surfaces may be used to separate mixtures in multiple components.