Patent ID: 8056730

Claim:
A magnetic separator for separating ferromagnetic materials having different magnetic permeability according to the different magnetic permeability of the materials, comprising: a rotatable magnetic roller; a non-magnetic idler tube around the rotatable magnetic roller so that the idler tube can slip rotationally with respect to the rotatable magnetic roller; a motor-driven roller; a belt around the idler tube and rotatable magnetic roller to form a closed loop around the rotatable magnetic roller and the motor-driven roller, which belt moves at the angular velocity of the motor-driven roller; and means for adjusting the angular velocity of the rotatable magnetic roller within a range of about 1% to 200% of the belt angular velocity, means for causing the ferromagnetic materials having higher magnetic permeability to adhere more strongly to the belt as it encircles the idler tube due to the magnetic attraction of the rotatable magnetic roller, means for causing release of the inert material to fall by gravity, means for causing the ferromagnetic material, due to the backing or advancing of the magnetic polarities, to rotate backward or forward respectively with respect to the travel direction of the belt; and means for causing the ferromagnetic materials to be released to and fall into different fall areas having ranges of increasing magnetic permeability at positions moving inwardly from below the edge of the belt due to the greater the magnetic permeability of the ferromagnetic material, the greater is its capacity to resist the combined action of slip and centrifugal force.