Abstract: To insure that rejects or scraps of composite materials such as printed wiring boards that consist of the mixture of metal and non-metal parts are separated into the metal and non-metal components with good precision so that both components can be recovered as recyclable valuables, the composite materials are broken into pieces by means of a shearing machine or the like and the pieces are thereafter ground with a hammer mill or the like to form a mixed powder consisting of metal and non-metal particles, which mixed powder is then fed continuously on to a belt conveyor inclined at an angle with respect to a line perpendicular to the direction of travel, whereby the metal particles are efficiently separated from the non-metal particles; the recovered metal particles being fed to an electrostatic separator to obtain higher grade of concentration by removing the non-metal inclusions.

Abstract: A multi-chamber inclined ball mill comprises a base, a frame-shaped support member rotatably supported on the base, and a grinding chamber rotatably supported on the frame-shaped support member. The grinding chamber is constituted of at least three cylindrical chambers each provided with outwardly tapered protrusions at its opposite ends and the cylindrical chambers integrally formed so that their longitudinal axes mutually intersect at the centers thereof and form a common grinding space at their region of intersection. The grinding chamber is supported on the frame-shaped support member such that the longitudinal axes of the cylindrical chambers intersect the axis of rotation of the frame-shaped support member at a single point and at one and the same angle.