High-gradient magnetic separator

Claim 1

A magnetic separator for filtrating magnetizable particles from a fluid, in which they are suspended, comprising a separation chamber having a pair of opposed chamber walls and a fluid inlet and a fluid outlet, means for causing said fluid to flow through said separation chamber along a predetermined flow path between said opposed chamber walls from said fluid inlet to said fluid outlet, a magnetic circuit comprising a pair of separate permanent magnetic devices connected with a closed magnetic circuit including yoke members and arranged with opposed mainly parallel pole surfaces on each side of an air gap, said opposed chamber walls of said separation chamber being disposed in said air gap adjacent to said opposed pole surfaces, respectively, said pair of opposed chamber walls being in magnetic contact with a respective one of said pole surfaces, said magnetic circuit for generating inside the separation chamber a magnetic field with a field direction substantially transverse to at least a portion of said flow path, and a matrix of a soft magnetic material arranged in said separation chamber to substantially fill up a part of the interior thereof extending between said pair of opposed chamber walls, said matrix thereby creating local magnetic gradients in said magnetic field, chamber inlet and outlet compartments being provided in said separation chamber at opposite ends of said matrix-filled part with respect to said flow path to be positioned outside said gap and communicating with said matrix as well as said fluid inlet and said fluid outlet, respectively, to define a main flow direction for said fluid through said matrix, each of said permanent magnetic devices comprising at least one member of a permanent magnetic material having a substantially linear demagnetization curve, said matrix comprising an arrangement of strands of said soft magnetic material extending mainly in planes substantially transverse to said field direction, a major portion of said matrix strands having an orientation transverse to said magnetic field direction and said main flow direction for said fluid, said closed magnetic circuit including said permanent magnetic devices and said air gap being proportioned as a whole to generate a substantially uniform magnetic field with an intensity, by which the individual strands throughout the matrix are substantially driven into a magnetic saturated state, when the separation chamber is positioned in said air gap.