1) Separation of materials with different bulk density by a punching or a throwing action whereby material with high bulk density is slung furthest away in a trajectory. 2) Ballistic separation takes advantage of both density and elasticity differences to separate inert and organic constituents. This method can be used in either initial processing or in the refinement of the final compost product. Compost is dropped on a rotating drum or spinning cone, and the resulting trajectory differences bounce glass, metal and stones away from the compost.