GB2153707A

GB2153707A - Electromagnetic rotary separator

Info

Publication number: GB2153707A
Application number: GB08403624A
Authority: GB
Inventors: Frederick Thomas Barwell
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-02-10
Filing date: 1984-02-10
Publication date: 1985-08-29
Also published as: GB8403624D0; GB2153707B

Abstract

A combination of electromagnetic and centrifugal forces is used to separate materials which conduct electricity from those which do not. In a preferred apparatus, material is fed by guides 1 and 2 into an annular shaped region of space 3 which is swept by a rotating electro-magnetic field generated by poly-phase winding 4. This field cases currents to flow within conducting particles of matter which will in turn react with the field producing forces which cause those particles to move in consonance with the rotating field. The accompanying centrifugal acceleration will cause the conducting particles to fly tangentially outwards whereas the non-conducting matter, being unaffected by the rotary action, will continue to move under the action of gravitational force in an undeflected path. The trajectories of conducting and non-conducting particles will therefore become differentiated by a powerful action and the two streams of material can be separated by suitably placed baffles 5. <IMAGE>

Description

SPECIFICATION Electrodynamic rotary separator This invention concerns improvements to apparatus for separating materials during disposal of waste products or as part of or in preparation of a manufacturing process.

The invention seeks to provide forms and arrangements of apparatus which will permit the practical application of a combination of electromagnetic and centrifugal forces to the separation of materials which conduct electricity from those which do not.

According to the invention the material to be sorted is fed in an axial direction into an annular shaped region of space surrounded by a poly-phase field winding of the type normally used in alternating current electric motors and arranged so as to generate a rotating magnetic field. Due to the action of this field, currents are caused to flow within conducting particles of matter. These currents will in turn react with the rotating field so as to produce forces on the conducting bodies causing them to move in consonence with the rotation of the field.

This rotation will be accompanied by a centrifugal acceleration which will cause the conducting particles to fly tangentially outwards whereas the motion of non-conducting matter will not be affected.

The non-conducting matter being unaffected by the rotary action will continue to move under the action of gravitational forces in an undeflected path.

The trajectories of conducting and non-conducting particles will therefore become differentiated by a powerful action.

In one embodiment of the invention aluminium beverage cans are separated from domestic refuse.

For example in an process for recovering the combustible material contained in municipal refuse the rubbish is first subjected to a size reduction process in a hammer mill which is followed bythe removal of ferrous metals by a magnetic separator.

After elimination of inert fines by means of a drum sieve, the combustible material is recovered by means of a drum sieve, the combustible material is recovered by means of an air-classifier and proces sed into pellets. The heavy fraction discharged from the air-classifier contains the aluminium and similar non-magnetic metals originally present in the muni cipal waste. This material is a present disposed of by landfill but, in the present invention, it is arranged to fall through space in the form of an annular jet which lies within the electro-magrietic influence of a polyphase field-coil. During passage through this space the conducting material is caused to take on a rotating motion inducing centrifugal force whereas the non-conducting matter continues to accelerate downwards under the action of gravity.Suitably placed baffles enables the two streams of matter to be separated.

Figure 1 shows a cross-section of the above embodiment wherein refuse material is directed by guides 1 and 2 into the annular space 3. Material within the space comes within the influence of a rotating field generated by field coils 4 and conduct ing substances are thrown outwards so as to pass on the remote side of barrier 5 whereas non-conducting matter will pass within this barrier.

An assembly whereby refuse is loaded into the apparatus by a conveyor belt and metal and residue are discharged at a lower level is illustrated in Figure 2.

The rotational acceleration of the conducting material will usually take place within an annular space separating two multi-pole field assemblies of laminated sheet steel one or both of which embodies a polyphase winding supplied with alternating current so that a magnetic flux passes approximately radially across the gap and which rotates at a speed consonent with the supply frequency and the number of poles provided. Under suitable circumstances either one or the other of the field assemblies may be dispensed with.

In other embodiments apparatus may be arranged to separate different metals; for example the interior surface of the external constraint may be protected by a wear resistant polymeric or ceremic coating and so shaped that the gravitational and centrifugal forces acting on a particle of matter may be approximately balanced as indicated in Figure 3. Thus a particle of mass "m" would be propelled upwards by a force equal to mw2r cos tp where r = radius of action, w is rotational velocity in rad./sec and ç is the angle of inclination of the walls of the container. The particle would also be subjected to a force acting in the opposite direction of magnitude mg sin ç where "g" is the force of gravity.Materials having higher frictional characteristics will be slowed down relative to those having lower frictional propertties. Thus the former will be more influenced by gravity than the latter and will accordingly be separated therefrom.

In other manifestations the mixture of nonconducting and conducting material may be fed into the area swept by the magnetic field by horizontal or inclined conveyor belts, air-jets, mechanical slingers or other suitable means.

1. A method of separating electrically conducting (metallic) material from non-conducting material by passing the mixture through space which is swept by a rotating electro-magnetic field so as to accelerate the conducting material in a tangential direction which accordingly takes a different path from that of the non-conducting material so becoming separated therefrom.

2. A method whereby the effect of electromagnetic forces on the path taken by metallic materials is augmented by centrifugal force.

3. A device for separating used aluminium beverage cans from domestic rubbish by a combination of centrifugal and electromagnetic forces.

4. A method of separating different metals or other electrically conducting bodies by causing them to rotate at different velocities within suitably shaped vessels.

Amendments to the claims have been filed, and have the following effect: *(a) Claim 4 above has been deleted or textually

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Electrodynamic rotary separator This invention concerns improvements to apparatus for separating materials during disposal of waste products or as part of or in preparation of a manufacturing process. The invention seeks to provide forms and arrangements of apparatus which will permit the practical application of a combination of electromagnetic and centrifugal forces to the separation of materials which conduct electricity from those which do not. According to the invention the material to be sorted is fed in an axial direction into an annular shaped region of space surrounded by a poly-phase field winding of the type normally used in alternating current electric motors and arranged so as to generate a rotating magnetic field. Due to the action of this field, currents are caused to flow within conducting particles of matter. These currents will in turn react with the rotating field so as to produce forces on the conducting bodies causing them to move in consonence with the rotation of the field. This rotation will be accompanied by a centrifugal acceleration which will cause the conducting particles to fly tangentially outwards whereas the motion of non-conducting matter will not be affected. The non-conducting matter being unaffected by the rotary action will continue to move under the action of gravitational forces in an undeflected path. The trajectories of conducting and non-conducting particles will therefore become differentiated by a powerful action. In one embodiment of the invention aluminium beverage cans are separated from domestic refuse. For example in an process for recovering the combustible material contained in municipal refuse the rubbish is first subjected to a size reduction process in a hammer mill which is followed bythe removal of ferrous metals by a magnetic separator. After elimination of inert fines by means of a drum sieve, the combustible material is recovered by means of a drum sieve, the combustible material is recovered by means of an air-classifier and proces sed into pellets. The heavy fraction discharged from the air-classifier contains the aluminium and similar non-magnetic metals originally present in the muni cipal waste. This material is a present disposed of by landfill but, in the present invention, it is arranged to fall through space in the form of an annular jet which lies within the electro-magrietic influence of a polyphase field-coil. During passage through this space the conducting material is caused to take on a rotating motion inducing centrifugal force whereas the non-conducting matter continues to accelerate downwards under the action of gravity.Suitably placed baffles enables the two streams of matter to be separated. Figure 1 shows a cross-section of the above embodiment wherein refuse material is directed by guides 1 and 2 into the annular space 3. Material within the space comes within the influence of a rotating field generated by field coils 4 and conduct ing substances are thrown outwards so as to pass on the remote side of barrier 5 whereas non-conducting matter will pass within this barrier. An assembly whereby refuse is loaded into the apparatus by a conveyor belt and metal and residue are discharged at a lower level is illustrated in Figure 2. The rotational acceleration of the conducting material will usually take place within an annular space separating two multi-pole field assemblies of laminated sheet steel one or both of which embodies a polyphase winding supplied with alternating current so that a magnetic flux passes approximately radially across the gap and which rotates at a speed consonent with the supply frequency and the number of poles provided. Under suitable circumstances either one or the other of the field assemblies may be dispensed with. In other embodiments apparatus may be arranged to separate different metals; for example the interior surface of the external constraint may be protected by a wear resistant polymeric or ceremic coating and so shaped that the gravitational and centrifugal forces acting on a particle of matter may be approximately balanced as indicated in Figure 3. Thus a particle of mass "m" would be propelled upwards by a force equal to mw2r cos tp where r = radius of action, w is rotational velocity in rad./sec and ç is the angle of inclination of the walls of the container. The particle would also be subjected to a force acting in the opposite direction of magnitude mg sin ç where "g" is the force of gravity.Materials having higher frictional characteristics will be slowed down relative to those having lower frictional propertties. Thus the former will be more influenced by gravity than the latter and will accordingly be separated therefrom. In other manifestations the mixture of nonconducting and conducting material may be fed into the area swept by the magnetic field by horizontal or inclined conveyor belts, air-jets, mechanical slingers or other suitable means. CLAIMS

Amendments to the claims have been filed, and have the following effect: *(a) Claim 4 above has been deleted or textually amended.

*(b) New or textually amended claims have been filed as follows:

4. A method of separating different metals or other electrically conducting bodies by causing them to rotate by electro-magnetic action at different velocities within suitably shaped vessels.

5. A method of enhancing the effectiveness of processes for separation of materials by magnetic means by introduction of the effect of centrifugal force.

6. A method whereby material to be sorted is presented to the separating process by falling freely under the action of gravity.