METHOD AND APPARATUS FOR SEPARATING FRAGMENTS OF NON-MAGNETIC METALLIC MATERIALS

Abstract: For separating fragments (12) of non-magnetic metallic materials, such as aluminium, zinc and copper, from a mixture (10) of such fragments (12) and fragments (11) of non-metallic materials, such as stones, earth, glass and plastics, the mixture (10) of fragments (11, 12) is discharged from a discharge unit (8) in such a manner that the fragments fall down towards a rotor unit (1, 7) which comprises on the one hand a rotating rotor (1) having a substantially horizontal shaft and juxtaposed and mutually spaced apart, axially extending permanent magnet bars (4) of alternating polarity and, on the other hand, a baffle (7) providing a mechanical screening between the rotor (1) and the discharge unit (8). The fragments (11, 12) are made to fall down towards the rotor (1) in a position which, as seen in the direction of rotation (P1) of the rotor, is ahead of the highest point of the rotor.

Description: METHOD AND APPARATUS FOR SEPARATING FRAGMENTS OF NON-MAGNETIC METALLIC MATERIALS The present invention relates to a method for sepa¬ rating fragments of non-magnetic metallic materials, such as aluminium, zinc and copper, from a mixture of such fragments and fragments of non-metallic materials, such as stones, earth, glass and plastics. The present invention also relates to an apparatus for carrying the method into effect. For the recovery of re-usable material, for example scrapped cars and all sorts of machines are broken up in so-called fragmentation plants where the scrap is disintegrated into fragments of different shapes and appearances, whereby a mixture of fragments of many different materials is obtained. Fragments of magnetic materials can be separated in a magnetic separator, and fragments of other materials can be separated in so-called flotation plants. One object of this invention is to provide a method of effectively separating fragments of non-magnetic metallic materials from a mixture of fragments from which fragments of magnetic materials have been separated, for example in a magnetic separator, said method being especially effective in procuding fragments that are free from impurities. This object is achieved, according to the invention, by means of a method which is of the type mentioned above and which is characterised in that the mixture of fragments is discharged from a discharge unit in such a manner that the fragments fall down towards a rotor unit comprising on the one hand a rotating rotor having a substantially horizontal shaft and juxtaposed and mutually spaced apart, axially extending permanent magnet bars of alternating polarity and, on the other hand, a baffle providing a mechanical screening between the rotor and the discharge unit, the fragments being made to fall down towards the rotor in a position which,. as seen in the direction of rotation of the rotor, is ahead of the highest point of the rotor. A further object of the invention is to provide a simple apparatus for carrying the method into effect. This object is achieved, according to the invention, by means of an apparatus which is characterised by a rotor having a substantially horizontal shaft and juxta- posed and mutually spaced apart, axially extending perma¬ nent magnet bars of alternating polarity, a discharge unit adapted to discharge a mixture of fragments in such a manner that the fragments fall down towards the rotor in a position which, as seen in the direction of rotation of the rotor, is ahead of the highest point of the rotor, and a baffle providing a mechanical screening between the rotor and the discharge unit. The baffle preferably is in the form of a cylinder surrounding the rotor and rotating in a direction opposite to the direction of rotation of the rotor. The invention will now be described in more detail, reference being had to the accompanying drawing. Fig. 1 is a schematic lateral view illustrating a separating apparatus according to the invention. Fig. 2 is an enlarged partial view illustrating a portion of the rotor of the separating apparatus. The separating apparatus shown in Fig. 1 comprises a cylindrical rotor 1 having an outer shell 2 made of iron. The rotor 1 has a horizontal shaft and is rotatable, via means not shown, in the direction of the arrow PI. Axial grooves 3 extending along the entire length of the rotor 1 are formed at equidistant intervals in the shell 2 across the entire circumference thereof (and not only across a part thereof, as has been shown for the sake of simplicity in Fig. 1 ) . Permanent magnet bars 4 of alternating polarity (N and S) are mounted in the grooves 3. The magnets 4 are of the type also known _> as "supermagnets", in this instance the magnets which are being marketed under the tradena e Neodyir.iuir.. The magnet bars 4 which are rectangular in cross-section, are formed in their side portions with longitudinally extending grooves in which attachment plates 5 for mount¬ ing, the magnet bars on the rotor shell 2 are inserted. Each attachment plate 5 is inserted in the grooves of two adjoining magnet bars 4 and are fixed to the rotor shell 2 by means of screws 6. cylinder 7 coaxial with the rotor 1 surrounds the rotor to form a mechanical screening around the rotor. The cylinder 7 is rotatable, via means nor shown, in the direction of the arrow P2 , i.e. in the direction opposite to the direction of rotation PI of the rotor 1. in a preferred embodiment, the cylinder 7 is made of stainless steel, but may of course be made of some other suitable material, such as plastics, glass fibres and the like, which is not subjected to inductive heating during rotation of the rotor 1. Above the rotor 1 , a funnel-shaped discharge unit 1 is mounted in a position which, as seen in the direction of rotation P1 of the rotor, is located slightly ahead of the highest point of the rotor. The position directly above this point will be called hereinafter the twelve o'clock position. In the embodiment illustrated, the discharge unit 8 is approximately in the twelve o'clock position. The discharge unit 8 can be set at different "hours" and may be connected for this purpose with two arms (not shown) rotatable about the common axis of the rotor 1 and the cylinder 7. The discharge unit 8 can be set at different positions between the ten o'clock position and the twelve o ' clock position. It should be noted that the discharge unit must always be set at a position such that the discharge therefrom will always occur ahead of the ten o'clock position. The discharge unit 8 cooperates with a conveyor belt 9 conveying a mixture 10 of fragments of different types. The mixture 10 of fragments may be obtained for example from a car fragmentation plant with which a magnetic separating plant is associated in which fragments. of magnetic materials are separated from the mixture. Such a screening plant may, optionally, also be provided between the fragmentation plant and the conveyor belt 9. The mixture 10 of fragments conveyed on the conveyor belt 9 to the discharge unit 8 contains fragments of non-magnetic metallic materials, such as aluminium, zinc and copper, and fragments of non-metallic materials, such as stones, earth, glass and plastics. The mixture 10 of fragments conveyed on the conveyor belt 9 is made to fall down into the discharge unit 8 from which it falls down towards the rotor 1 rotating at high speed and the cylinder 7 rotating at low speed in the opposite direction, towards a position ahead of the twelve o'clock position. Fragments 11 of non- metallic materials fall by gravity and, to some extent, by the assistance of the rotating cylinder 7 down to the left (Fig. 1) of the rotor 1 where they can be col¬ lected in a suitable receptacle (not shown). In contrast to the fragments 11 of non-metallic materials, fragments 12 of non-magnetic metallic materials are affected by the alternating field generated by the permanent magnet bars 4 on the rotating rotor 1 and are repelled a slight distance away from the rotor 1 and, at the same time, are carried along a distance in the direction of rotation of said rotor before they fall down to the right (Fig. 1) of the rotor 1 where they can be collected. In this manner- the fragments of the two different types of material are separated from one another. It has been found that the percentage purity of the fragments of the materials to be re-used, i.e. the fragments 12 falling down to the right of the rotor 1, is increased if the discharge unit 8 is rotated out of the twelve o'clock position, i.e. to the left in Fig. 1. The reason for this presumably is that the frag- D ments will then fall from a slightly greater height so that some fragments of non-magnetic metallic materials with adhering impurities, such as earth and dirt, are thrown about during their fall to such an extent that the impurities are released from the fragments before the fragments are caught by the alternating field to be carried along thereby. The farther ahead of the twelve o'clock position the discharge unit 8 is positioned, the higher the fragments must be lifted in order to be carried along in the direction of rotation PI of the rotor 1. Since the lifting power provided by the alternating field is not sufficient, impure fragments from which the impurities have not been released during the fall of the fragments from the discharge unit 8, will fall down to the left of the rotor 1 together with fragments of non-metallic materials. The farther ahead of the twelve o ' clock position the discharge unit 8 is positioned, the higher will be the proportion of the impure fragments of non-magnetic metallic materials falling down to the left of the rotor 1. As will appear, the purity of the fragments 12 falling down to the right of the rotor 1 is increased at the cost of the yield, but this is acceptable because the increased purity is a prerequisite for making the recovery and re-use of the materials profitable.

Claims: CLAIMS 1. A method for separating fragments (12) of non¬ magnetic metallic materials, such as aluminium, zinc and copper, from a mixture (10) of such fragments (12) and fragments (11) of non-metallic materials, such as stones, earth, glass and plastics, c h a r a c t e r ¬ i s e d in that the mixture (10) of fragments (11, 12) is discharged from a discharge unit (8) in such a manner that the fragments fall down towards a rotor unit (1, 7) comprising on the one hand a rotating rotor ( 1 ) having a substantially horizontal shaft and juxtaposed and mutually spaced apart, axially extending permanent magnet bars (4) of alternating polarity and, on the other hand, a baffle (7) providing a mechanical screening between the rotor (1) and the discharge unit (8), the fragments (11- 12) being made to fall down towards the rotor (1) in a position which, as seen in the direction of rotation (P1 ) of the rotor, is ahead of the highest point of the rotor. 2. A method as claimed in claim 1, c h a r a c - t e r i s e d in that the baffle which is in the form of a cylinder (7) surrounding the rotor (1), is rotated in a direction of rotation (P2) opposite to the direction of rotation (PI) of the rotor. 3. An apparatus for carrying out the method, claimed in claim 1, for separating fragments (12) of non-magnetic metallic materials , such as aluminium, zinc and copper, from a mixture (10) of such fragments (12) and fragments (11) of non-metallic materials, such as stones, earth, glass and plastics, c h a r a c t e r i s e d by a rotor (1) having a substantially horizontal shaft and juxtaposed and mutually spaced apart, axially extending permanent magnet bars (4) of alternating polarity, a discharge unit (8)adapted to discharge a mixture (10) of fragments in such a manner that the fragments fall down towards the rotor (1) in a position which, as seen in . the direction of rotation (P1) of the rotor, is ahead of the highest point of the rotor, and a baffle (7) providing a mechanical screening between the rotor ( 1 ) and the discharge unit (8). 4. An apparatus as claimed in claim 3, c h a r ¬ a c t e r i s e d in that the baffle is in the form of a cylinder (7) surrounding the rotor (1) and adapted to rotate in a direction of rotation (P2) opposite to the direction of rotation (P1) of the rotor (1).

Inventors: ANDERSSON EINAR, ANDERSSON, EINAR
Applicants: AELMHULTS ELEKTROMEKANISKA EIN, AELMHULTS ELEKTROMEKANISKA EINAR ANDERSSON AB
Application year: 1989
Main classification: B03C1
IPC codes: B03C1