Abstract: An apparatus comprises a rotor supported for rotation about a longitudinal axis. The rotor comprises an elongate tubular member enclosing a substantially cylindrical space, the elongate tubular member having a first open end defining an inlet, and a second open end defining an outlet. The apparatus includes at least one electrically conductive element for generating a magnetic field when electric current flows therethrough and for controlling rotation of the rotor. At least a part of at least one said electrically conductive element is aligned axially with at least a part of said elongate tubular member. The elongate tubular member comprises conveying means adapted so that upon rotation of said rotor, at least one body is caused to move in a direction from said inlet toward said outlet, through the substantially cylindrical space.