US 4,125,191 A · Magnetic separation of materials

Abstract

Fragments of ferromagnetic material, such as tin can pieces, are sorted by size on apparatus including an inverted conveyor that carries fragments that have been previously oriented with their longest axes placed in parallel directions past a line of magnets spaced progressively further apart in the direction of orientation of the fragments. The magnets attract the fragments strongly to the conveyor directly under the magnets, but progressively more weakly in those spaces between the magnets so that the shorter pieces separate gravitationally from the conveyor sooner than the longer pieces. Fragments having varying magnetic susceptibility, such as, for example, tin can pieces with and without attached normally round aluminum tops, are also separated according to their magnetic susceptibility by conveying the fragments beneath carefully spaced magnetic devices whereby the fragments of lower susceptibility drop from the conveyor sooner than those of higher susceptibility due to the weaker magnetic field between magnetic devices. The spacing between magnetic devices, for example, can be slightly greater than the diameter of an aluminum top in the case of the exemplary fragments.

Claims17

Dependent claims

A method for continuously separating various size fragments of ferromagnetic material from one another according to their size including the steps of:

(a) orienting the fragments upon a support surface so their respective longest dimensions extend in a common direction;
(b) conveying the fragments while they are on the support surface along a line of magnetic devices which maintain the initial orientation of the fragments and which are arranged to attract the fragments to the support surface, the magnetic devices being located along the fragment conveying direction and spaced apart from one another progressively greater distances along the direction of orientation of the longest dimensions of the fragments;
and
(c) exposing the fragments to a force tending to separate the fragments from the support surface at least when the fragments pass between adjacent magnetic devices spaced apart a sufficient distance such that their magnetic influence is insufficient to retain the smaller of the passing fragments on the support surface.

1 more element

A method of classifying and separating fragments according to their magnetic susceptibility comprising:

(a) placing fragments having varying magnetic susceptibility upon a movable supporting and conveying surface;
(b) conveying the fragments by means of the moving surface past a line of magnetic devices the field strengths of which are maintained constant during normal operation and that are spaced apart from each other by predetermined distances, and each of which provides a steady predetermined magnetic field tending to strongly attract the fragments passing directly opposite the magnetic devices to the moving surface and to only weakly attract the passing fragments to the moving surface between the magnetic devices;
and
(c) exposing the fragments to forces tending to cause their separation from the moving surface while they are conveyed past the magnetic devices;
whereby fragments of lower magnetic susceptibility will be separated from the moving surface while they pass between adjacent magnetic devices, and fragments of higher magnetic susceptibility will be conveyed at least to the last of the magnetic devices in the line.

2 more elements

Apparatus for continuously separating fragments of ferromagnetic material from one another according to their size, comprising means for orienting the fragments so their respective longest dimensions extend in a common direction;

a line of magnetic devices;
means for supporting and conveying the fragments from the orienting means along the line of magnetic devices, said devices being arranged to maintain the initial orientation of the fragments and to attract the fragments against the supporting means while they are conveyed, the magnetic devices being spaced apart from one another progressively greater distances along the direction of orientation of the longest dimensions of the fragments whereby the fragments can be separated from the supporting means by a separating force at least when the fragments pass between adjacent magnetic devices that are spaced sufficiently apart such that their combined attractive force is insufficient to retain the fragments against such separating force.

Apparatus for classifying and separating fragments in accordance with their magnetic susceptibility comprising:

(a) a fragment conveying means including a movable supporting surface;
(b) means for feeding magnetic fragments having varying magnetic susceptibility onto the movable supporting surface of the conveying means;
(c) a row of magnetic devices each having a constant field strength during normal operation and being spaced apart by predetermined distances along the direction of travel of the conveying means, said magnetic devices being capable of attracting the fragments towards and against the supporting surface in opposition to a force tending to separate them from the supporting surface when the fragments are conveyed past the magnetic devices;
(d) the predetermined distance between the magnetic devices corresponding to the distance that results in the magnetic field between adjacent magnetic devices being insufficient to attract and hold fragments having a susceptibility below a predetermined level to the supporting force in opposition to such separating force;
whereby the fragments can be separated from the supporting surface by a separating force in accordance with their susceptibility at least while the fragments are being conveyed between magnetic devices.

2 more elements

Dependencies are inferred from the claim text.

Magnetic separation of materials

Life of this patent

Magnetic separation of materials

Life of this patent

Abstract

Claims17