Magnetic roll-type separator

A magnet roll including a plurality of axially disposed substantially cylindrical permanent magnets, each magnet comprising an axial segment of the roll, each segment having a peripheral surface and having axially opposed ends, the segments being disposed in the roll so that adjacent magnet roll segment ends are of like polarity, and pole pieces disposed between adjacent ends of the segments, each pole piece comprising a laminate of two discs disposed adjacent one another, each disc being sufficiently thin to be saturated by magnetic flux lines, each disc defining a peripheral flange which projects from the disc in an axial direction, so that the pole piece has a larger cross-sectional area at its periphery, and so that the axial width of the flange of a disc is no more than five times the axial width of the disc;

• the discs of each laminate of two discs having their flanges projecting away from each other;
• each disc extending axially partially over the adjacent segment;
• the flanges further being shaped and disposed for directing magnetic flux lines toward the surface of the roll the flange of each disc has a radially innermost portion thereof which is at a maximum axial width, the flange of each disc has a radially outermost portion thereof at the periphery of the disc which is at a minimum axial width, the axial width of the flange of each disc tapers from the maximum width at the radially innermost portion to the minimum width at the radially outermost portion at the peripheral edge of the flange, and the flanges of adjacent discs of a pole piece thus defining a frusto-triangular section.