WO2013167591A1

WO2013167591A1 - Eddy-current separator

Info

Publication number: WO2013167591A1
Application number: PCT/EP2013/059488
Authority: WO
Inventors: Rainer Bunge
Original assignee: Hochschule Rapperswil
Priority date: 2012-05-10
Filing date: 2013-05-07
Publication date: 2013-11-14

Abstract

An eddy-current separator having a conveying means (2) and having at least one exciter (5, 14) for an alternating magnetic field is characterized in that the eddy-current separator comprises at least one discharging means (17, 19, 20, 21, 25, 32) by means of which the particles repelled by the alternating magnetic field are captured and transported away or deflected out of their flight path.

Description

TITLE

eddy

TECHNICAL FIELD The invention falls within the field of bulk material sorting and is directed to an eddy current separator according to the preamble of claim 1. In particular, the invention relates to a device for separating particles according to their electrical conductivity by means of eddy current sorting. STATE OF THE ART

State of the art are band Wirbelstromscheider in which the feed material is transported by conveyor belt through an alternating magnetic field. Figures 1 and 2 show Wirbelstromscheider, which are known from the prior art. The conveyor belt is driven by a first drum and deflected by a second drum. In general, the alternating magnetic field is generated by a fast-rotating cylinder, on the outer circumference of which permanent magnets are mounted. This cylinder can be referred to as a flywheel. This flywheel is mounted in most Wirbelstromscheidem inside a pulley of the conveyor belt, and relative to the tail pulley centric or eccentric. For deposition of coarse particles, the flywheel is usually rotated with the conveying direction, for the deposition of small particles often against the conveying direction. Conductive particles are repelled by the alternating magnetic field and lift off the conveyor belt. By superimposing this repulsive force with the inertial force in the transport direction and the vertically acting weight, results in a throwing trajectory, which is different for conductive particles than for non-conductive particles. Consequently, the conductive particles can not be separated from them separating conductive particles by means of a separating blade.

The problem with band eddy current separators is that the trajectories of the conductive particles-depending on the direction of rotation of the pole wheel, grain size, shape and orientation of the particles-can run in such a way that a sharp separation is hindered. One such effect is the segregation of material that travels along a throw trajectory, by grain size, with the coarser particles flying further than the smaller ones. This results in a superimposition of the trajectories of small conductive particles with coarse non-conductive particles, which leads to a dilemma in the setting of the cutting edge. If the small conductive particles are transferred into the concentrate by means of a low-setting cutting edge, the coarse, non-conductive particles inevitably separate out, thus worsening the concentrate quality. It has also been found that the particles repelled by the pole wheel spring up almost vertically and fall back into the slot between the cutting edge and the deflection roller of the conveyor belt when falling back. As a result, these particles are mispicked in the nonconductive material. This effect mainly affects small conductive particles and this especially when the pole wheel rotates against the conveying direction.

It is also very unsatisfactory that band eddy current separators can usually only be equipped with one pole wheel since they have only one deflection drum on which the conductive particles are deflected in their trajectory so that they can be drawn off by means of a separating blade. If several pole wheels were positioned with axes perpendicular to the conveying direction under the upper strand of the belt, the high-jumping conductive particles would fall back onto the belt without being able to be discharged. To avoid this problem, there are types of tape Wirbelstromscheidern in which under the conveyor belt several pole wheels are mounted obliquely to the conveying direction. The conductive particles are then deflected sideways bouncing out of the direction of transport and may, for example, be detected after falling over one or both sides of the conveyor belt. The disadvantage here However, with wide conveyor belts, a large number of rotor wheels must be provided in order to deflect conductive particles from the middle of the belt to the edges. While the conventional eddy current separators described above have an "open-pole" alternating magnetic field, there are also references in the patent literature to the use of "closed-pole" systems (eg JP571 17353, DE19838170, US5,080,234, EP2289628). Closed-pole magnetic fields are characterized in that the feed material is conveyed through between two opposite-pole magnets. In the case of open-pole arrangements, on the other hand, the north and south poles of the magnets forming the field lie approximately in one plane and the feed material passes over it.

In particular, when conventional eddy current separators are used for the separation of fine-grained material (<8 mm), the selectivity is greatly influenced by disturbing effects. Two of these disruptive effects are:

1. Grain size effect: The segregation according to the grain size is shown in FIG. 1 outlined. At the discharge of a conveyor belt coarser particles fly further than fine-grained particles. This results in a superimposition of the trajectories of small conductive particles with coarse non-conductive particles, which leads to a dilemma in the setting of the cutting edge. If you also want to take the small conductive particles by a low set cutting in the concentrate, inevitably the coarse non-conductive particles are deposited in the concentrate and thus deteriorate its quality.

2. Abnormal jumps: Depending on the shape and orientation on the belt particles ejected from the pole wheel can jump up almost vertically, fall back into the slot between the cutting edge and the deflection roller of the conveyor belt, and are consequently mislaid in the non-conductive residue. This effect mainly affects fine-grained conductive

Particles as in FIG. 2 shown. PRESENTATION OF THE INVENTION

The invention has for its object to provide a device that ensures the targeted discharge of the conductive particles from the alternating magnetic field, without the above-mentioned disadvantages must be taken into account.

This object is solved by the subject matter of claim 1. Accordingly, an eddy current separator is formed with a delivery medium and at least one exciter for an alternating magnetic field. The Wirbelstromabscheider further comprises at least one discharge, which detects the repelled particles from the alternating magnetic field and transported away or deflected from its trajectory.

The delivery agent or the delivery aid influences the trajectories of the conductive particles repelled by the pathogen, so that these can be supplied to at least one further device, such as a separating blade. Particularly preferably, the discharge means causes mechanical forces on the particles, thus influencing the trajectories of flight. Alternatively or additionally, the discharging agent causes electrostatic forces on the particles, thus influencing the trajectories of flight. Preferably, the eddy current separator for separating the particles has a separating blade, which is arranged downstream of the discharge means in the direction of movement of the particles, so that the detected particles are guided to the surface of the separating blade. The other particles, which are not detected, do not reach the cutting edge. For example, these particles fall in front of the cutting edge. In this embodiment, therefore, a discharge means and in addition to the discharge means a separating blade is present. The separating blade is preferably arranged at a distance from the discharge means. The cutting edge itself is not the discharge or the discharge aid, but as an additional element available.

Further embodiments are given in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will be described below with reference to the drawings, which are given by way of illustration only and are not to be interpreted as limiting. In the drawings show:

1 shows a Wirbelstromscheider from the prior art;

Fig. 2 shows a vortex flow separator of the prior art;

3 shows an eddy current separator according to a first embodiment of the present invention;

4 shows a Wirbelstromscheider according to a second embodiment of the present invention;

5 shows a Wirbelstromscheider according to a third embodiment of the present invention;

6 shows an eddy current separator according to a fourth embodiment of the present invention;

7 shows a Wirbelstromscheider according to a fifth embodiment of the present invention;

8 shows a Wirbelstromscheider according to a sixth embodiment of the present invention;

9 shows a representation of measurement results; and

Fig. 10 representation of a detail of the second, third and fourth

Embodiment. DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 3 to 8 show various embodiments of an eddy-current separator with a delivery medium and at least one exciter 5 shown for a magnetic alternating field. The eddy current separator comprises at least one discharge means, which detects the particles repelled by the alternating magnetic field and removes them or diverts them from their trajectory. The discharge can also be referred to as Austragshilfe.

The alternating magnetic field is preferably provided by a pole wheel 5.

The fluid is here a conveyor belt 2, which rotates about two pulleys 3, 4. One of the two pulleys 3, 4 is actively driven. The conveyor belt 2 is charged with particles at one end. This end bears the reference numeral 1. At the other end, the particles are exposed to the alternating magnetic field, so that the particles are separable from each other. The alternating magnetic field is provided by a pathogen, here a flywheel 5. For separation, the eddy current separator here has a separating edge 6. Conductive concentrate 8 is repelled due to the alternating magnetic field from the surface or conveying surface 33 of the conveyor belt 2 and is thereby guided to the surface of the cutting edge 6. Non-conductive particles 7 fall through the gap 34 between the conveyor end and the cutting edge. 6

FIG. 3 shows a first preferred embodiment of the eddy current separator. The flywheel 5 is mounted centrally to the deflection roller 4 and rotates in the conveying direction. The pole wheel 5 is thus in synchronism with the conveying direction. Particles which jump vertically above the pole wheel 5 fall into the effective range of the discharge means 32, which here in this embodiment has the shape of a brush or brush roller 32.

In a first variant of the first embodiment, the brush 32 or the brush roller 32 is designed to rotate. Particularly preferably, the brush or brush roller 32 rotates in such a way that the movement to the conveying medium 2 is synchronous. With regard to the rotating brush roller can be spoken of an active discharge. The particles are detected by the bristles of the brush 32 and laterally thrown over the separating blade 6, so that they are transferred to concentrate 8. Here, the discharge is as stated in the form of a rotating brush or brush roller 32 executed. Brush rollers have proven particularly useful because the bristles can avoid oversized, lying on the tape, non-conductive particles and thus the risk of grits between the conveyor belt and discharge device is prevented. The compromises in the adjustment of the speed of the pumped medium, also referred to as belt speed, and the adjustment of the cutting blade 6, especially when processing broad particle size spectra, are no longer necessary after installation of the discharge means 32, since all the particles (conductive) which jump up from the belt are deflected by the brush 32 thrown over the cutting edge 6. The movement of the conductive particles is thus actively influenced by the brush or brush roller 32.

In a second variant of the first embodiment, the brush 32 and the brush roller 32 is stationary or substantially stationary or stationary to the conveying medium 2. This discharge can also be referred to as a passive discharge. The passive discharge has a positive effect on the separation result, especially by avoiding the erroneous jumps described above in connection with FIG. Thus, in the case of FIG. 3 embodiment shown a significant improvement of the separation result, even if the brush stood still. Particles that jump vertically above the flywheel 5 bounce off the bristles of the discharge aid 32 designed as a brush, fall perpendicularly back onto the belt and thus again have the opportunity to "jump off" and thus to discharge correctly into the concentrate 8.

FIG. 4 shows a second embodiment of the dispensing means. Here, the discharge means has the shape of a suction device 18. The suction device 18 detects the jump over the flywheel 5 particles and leads them into the concentrate 8. Particles that jump vertically above the flywheel 5, get into the catchment area of the suction device 18 and are deposited via an aero-cyclone 21, the suction side in front of a fan 20th is installed. The separation of the particles from the air stream could also done differently. As suction device such devices are understood in which the high-jumping material particles are detected and removed by an air flow. In this sense, a blowing device or an air knife, which blows the high-jumping particles with a sharp air flow eg laterally, can represent a suction device.

In Fig. 10 right, a suction device 18 is shown, which is equipped at the intake with a diffuser 18a. The diffuser consists of a grid or fins that break the incoming airflow and split it into single streams. Experiments have shown that the installation of such a diffuser can have a very positive effect on the separation result in comparison with an "open" suction channel, namely an air flow which may have uncontrollable vortices in front of an open suction channel (FIG lead to the fact that the feed area (18b) is not aligned flat and parallel to the surface 33 of the pumped medium 2, but partly can penetrate to the pumped medium 2. From there, also such material is sucked in, which was not repelled by the flywheel 5, and This results in the irregular and undesirable distribution of the particles 7, 8 shown in FIG. 10. The diffuser (FIG. 10, right) ensures that the intake region 18b of the suction device 18 is level and parallel to the surface 33, and only the The lower edge is detected by the suction device via this plane The diffuser is typically located less than 150 mm above the conveyor belt, which limits the processable grain size accordingly.

An advantage of the second embodiment is that conventional belt eddy current separators can be retrofitted with a suction device 18. Experiments have shown that in the eddy current sorting of small particles can be achieved by the additional attachment of a suction device, an increase in the application of conductive particles of about 2-5%.

The suction device 18 can stand alone or in combination with the brush or the brush roller 32 according to the first embodiment be used.

In the figure 4, the embodiment of the combination brush roller 32 and suction device 18 is shown. The discharge means in this case comprises the brush roller 32, an intake passage 19, a blower 20 and a separation cyclone 21. Intake channel 19, blower 20 and separation cyclone 21 here form the suction device 18. The high above the flywheel 5 particles are detected by the brush roller 32, advised from there into the suction device 18 and are finally transferred via the separation cyclone 21 into the concentrate 8.

The suction device has the advantage that in the eddy-current sorting of small particles (0.5-6 mm), the additional application of such a discharge aid results in an increase in the application of conductive particles to about 10%.

In the figure 5, a third embodiment of the Wirbelstromscheiders is shown. With this embodiment, a similar effect as with a suction device according to the second embodiment can be achieved. The third embodiment comprises as discharging means a blowing device 25 oriented transversely to the particle trajectories. The blowing device 25 has the effect of an air knife and may also be designated as such. With the blowing device 25, an air flow is provided in the conveying direction, which acts on the above the flywheel 5 high-jumping particles. The air flow ensures efficient supply of the particles to the separating blade 6.

The blowing device 25 can be used alone as the sole discharge means or in combination with the suction device 19, as shown in FIG. Here, the air flow of the blowing device 25 is directed substantially to the intake passage 19.

In a further variant, the brush or the brush roller 32 according to the first or the second embodiment may also be arranged. Consequently, the discharge means then consists of the Suction device 18, the blowing device 25 and the brush or the brush roller 25th

In the figure 6 a fourth embodiment of the Wirbelstromscheiders is shown. Here, the eddy current separator comprises a plurality of exciters, here in the form of pole wheels 5, 14. The pole wheels are arranged here below the conveying path of the conveying medium 2 and ensure that the particles jump up from the conveying medium 2. Above the conveying medium 2, at least one discharge means is provided, via which the particles can be detected and removed from the conveying medium 2.

Particularly preferably, the plurality of pole wheels 5, 14 are arranged transversely below the conveying medium, which here has the shape of a conveyor belt.

In the figure 6, such a device is shown in two-stage design. Here, the material is conveyed via a first flywheel 14 and then via a second flywheel 5. Small conductive particles are z. B. deposited over the front fast-running flywheel 14, while large particles are separated with the slower running rear flywheel 5.

A discharge means is arranged here above the front rotor 14. The dispensing means is shown here as a suction device 19, but could also be in the form of another dispensing means described in connection with the embodiments described herein. In other variants, also discharge means described herein can be arranged in the region of the rear pole wheel 5.

The arrangement of two pole wheels 5, 14 a greater efficiency is achieved. On the one hand, the spreading is increased if the conductive particles pass through a plurality of pole wheels 5, 14 one after the other and thus have several opportunities to get into the concentrate. On the other hand, the pole wheels 5, 14 by adapting Polraddesign and running speed to different Materials and grain sizes are optimized. Large conductive particles would z. For example, in the embodiment shown in FIG. 2, it is deposited over the front low-speed flywheel, while small particles are separated with the fast-running rear flywheel.

The high quality of the concentrate obtained by means of the discharge aid 19 above the rotor 14 is noteworthy, since the discharge aid only detects conductive particles, ie only those that jump up. Another possibility when using eddy current separators with a plurality of pole wheels, which are provided with discharge means according to the invention, is to position a knocking roller or knocking device between the pole wheels, which moves the particles lying on the conveyor belt 2 from the bottom by impact. Since the orientation of conductive particles on the belt is essential for their discharge, it can happen that unfavorably positioned conductive particles are not deposited with the first flywheel 14. After a forced by the knocking rearrangement of these particles can then be deposited with the second pole 5 often. With respect to the embodiments with the suction device 18, there is the possibility to easily integrate a dust extraction, for example, by switching behind the blower 20, a cloth filter. Furthermore, the extracted material can be further separated in the air stream, for example, by a Aeroklassierung by a zigzag layer. Experiments have shown that with fine-grained mixtures of aluminum shavings and sand with the embodiment shown in Figure 6, the output of aluminum through the second flywheel 14 and the Austragshilfe 19 increased by about 15% compared to the conventional eddy current separator with only a single flywheel 5. Further, in all of the embodiments shown herein for the formation of maximum jump height of the conductive particles, especially at particle size of <8mm, it may be advantageous to let the belt run slowly and to rotate the flywheel 5, 14 against the direction of conveyance. In this case, the conductive jump However, particles are almost vertically high and, as described above, can not overcome the cutting edge. Here, the embodiments with the rotating brush 32, the blowing device 25 and suction device 18 have the advantage that the belt speed and direction of rotation can be optimized without the need to compromise to achieve a running over the cutting edge Wurftrajektorie.

In another embodiment, not shown in the figures, the discharge means acts with electrostatic forces on the particles.

FIG. 7 shows a fifth embodiment of an eddy current separator. The discharge is stationary or stationary with respect to the pumped medium. It can also be spoken of a passive discharge.

In FIG. 7, the passive discharge means in the form of a broom 17 is shown. The broom 17 is installed here above the flywheel 5 transversely to the conveying medium or to the conveyor belt. FIG. 8 shows a further embodiment of the passive discharge means. Here, the discharge means has the shape of a flap 17 suspended above the flywheel. The flap 17 is preferably made of plastic.

In the embodiments according to FIGS. 7 and 8, pole wheel 5 is mounted centrically to the deflection roller and rotates in the conveying direction. Particles that jump vertically above the flywheel 5, bounce off the discharge 17, fall back on the fluid and thus get once again opportunity to jump and thus to a correct discharge into the concentrate. Experiments have shown that the spreading of a Wirbelstromscheiders could be significantly improved after the discharge means according to Figures 7 and 8 was installed. The passive discharge means according to the fifth and sixth embodiments can also be combined with the active discharge means according to the first to fourth embodiments. In this context, it should be mentioned that all embodiments can be combined with each other as desired and that the same parts are provided with the same reference numerals.

FIG. 9 shows the results of a test series in which a mixture of glass and aluminum with a grain size of 2-4 mm was processed on an eddy current separator with a centrally arranged rotor. The passive discharge aid was a broom as shown in FIG. 7 outlined. The application (mass aluminum in the concentrate / mass aluminum in the feed material) was 77.4% with the rotor in synchronism ("clockwise", as shown in FIG. 7) without the cover 71 according to the invention and with this cover 77.6% total output was increased, with 77.3% yield without dispensing aid and 83% dispensing with dispensing aid, so that the dispensing of the eddy-current separator was around 7.5% due to the "passive" dispensing aid according to the invention, which was very simple and inexpensive to install. elevated. In contrast to a separating blade, the discharge aid according to the invention captures the particles above the dropping level.

With regard to all embodiments shown here, the pole wheels 4, 15 can be arranged centrically or eccentrically to the roller or deflecting drum 3, 4 of the conveying medium 2.

REFERENCE LIST Schurre

conveyor belt

idler pulley

flywheel

cross-cut

non-conductive residue

conductive concentrate

Discharge agent (brush)

flywheel

Discharge agent (broom, cloth)

Discharge aid (suction device)

intake port

fan

separating cyclone

Discharge agent (blowing device)

Discharge agent (brush)

surface

gap

discharge edge

Claims

1. eddy current separator with a pumped medium (2) and at least one exciter (5, 14) for a magnetic alternating field (5), characterized in that the Wirbelstromabscheider at least one discharge (12, 17, 18, 25, 32), which the detected by the magnetic alternating field (5) repelled particles and transported or distracted from their trajectory.

2. Wirbelstromscheider according to claim 1, characterized in that for separating the Wirbelstromscheider a separating blade (6), which in the direction of movement of the particles after the discharge (12, 17, 18, 25, 32) is arranged, so that the detected particles to the surface of the cutting edge (6) are guided.

3. eddy current separator according to claim 1 or 2, characterized in that the discharge means is installed such that in the space between the exciter of the alternating magnetic field and the discharge means (12, 17, 18, 25, 32) deflected conductive particles deflected from their trajectory be, with the deflection of the particles over, in particular above, the Absprungebene occurs.

4. Wirbelstromabscheider according to any one of the preceding claims, characterized in that the conveying medium (2) comprises a surface or conveying plane (33) and that the discharge means (12, 17, 18, 25, 32) spaced from the surface or conveying plane (33) is arranged ,

5. Wirbelstromscheider according to any one of the preceding claims, characterized in that the discharge means (12, 17, 18, 25, 32) acts with mechanical forces on the particles, so that their deflection by the discharge means (12, 17, 18, 25, 32) is effected by said mechanical forces, wherein the mechanical forces are in particular shock, impact or air movement.

6. Eddy current separator according to one of the preceding claims, characterized in that the discharge means (12, 17, 32) has a plurality of bristles, which are preferably aligned in the direction of the exciter (5, 14) of the alternating magnetic field.

7. Wirbelstromscheider according to any one of the preceding claims, characterized in that the discharge (12, 17, 18, 25, 32) with respect to the alternating field or the pumped medium is quiescent or substantially stationary or stationary or substantially stationary and / or that Discharge means (12, 17, 18, 25, 32) with respect to the alternating field or the conveying medium is movable, wherein the movable discharge preferably has a drive.

8. Wirbelstromscheider according to any one of the preceding claims, characterized in that the discharge means (12, 17, 18, 25, 32) opposite a pathogen (14) of an alternating magnetic field is installed, which exciter (14) spaced from the discharge edge (35). or not in the region of the discharge edge (35) of the pumped medium is installed.

9. eddy current separator according to one of the preceding claims, characterized in that the alternating magnetic field by a flywheel (5, 14) is provided, wherein the discharge means (12, 17, 18, 25, 32) in the region of the pole wheel (5, 14) or above the pole wheel (5, 14) is arranged.

10. Eddy current separator according to one of the preceding claims, characterized in that the gap between the exciter (5, 14) of the alternating magnetic field and the discharge means (12, 17, 18, 25, 32) is less than 20 times the maximum particle diameter , preferably less than 0 times.

11. eddy current separator according to one of the preceding claims, characterized in that the part of the discharge aid (12, 17, 18, 25, 32) coming into contact with the conductive particles consists of a plastic.

12. eddy current separator according to any one of the preceding claims, characterized in that the discharge means is a suction device (18) which is adapted to detect repelled particles from the alternating magnetic field and transported away.

13. eddy current separator according to claim 12, characterized in that the exciter for the alternating magnetic field at least one below the conveying medium (2) arranged transversely to the conveying direction Polrad (5, 14) and that the suction device (18) relative to the pole wheel (5, 14) is located and is adapted to detect the repelled particles from the flywheel (5, 14) and transported away.

14. eddy current separator according to claim 13, characterized in that at least one pole wheel (5, 14) spaced from the discharge edge (35) or not in the region of the discharge edge (35) of the pumped medium is installed.

15. eddy current separator according to one of the preceding claims, characterized in that between two pole wheels (5, 14) is positioned from below against the pumped medium beating device.

16. eddy current separator according to one of claims 12 to 15, characterized in that the suction device (18) is provided on the suction side with a diffuser having a plurality of openings in a substantially parallel to the medium to be conveyed, in particular parallel to its surface (33 ) on which the particles rest, are aligned plane.

17. eddy current separator according to one of claims 12 to 16, characterized in that the feed plane of the suction device (5) is located less than 150 mm from the outer circumference of the pole wheel, preferably less than 80 mm.

18. Eddy current separator according to one of the preceding claims, characterized in that the at least one discharge means is an active discharge means (18, 25, 32) which deflects the repelled particles from the alternating magnetic field from its trajectory.

19. eddy current separator according to claim 18, characterized in that the active discharge means is a rotating roller (32), in particular a brush roller, is.

20. Wirbelstromscheider according to claim 18 or 19, characterized in that the active discharge means is a suction device (18), and / or that the active discharge means is a blow-out device (25), in particular an air knife.

21. eddy current separator according to one of claims 18 to 20, characterized in that the active discharge in the range of action of an exciter (5, 14) is mounted for a magnetic alternating field, which is located directly in the region of the discharge point of the pumped medium (2)

22. eddy current separator according to one of claims 18 to 21, characterized in that the active discharge is mounted in the region of action of an exciter for an alternating magnetic field which is spaced from the region of the discharge edge (35) of the pumped medium (2) or which is not located in the region of the discharge edge (35) of the pumped medium.

23. eddy current separator according to one of the preceding claims, characterized in that the discharge means is a passive discharge, in particular a partial cover (17), which (s) above the exciter (5, 14) is arranged.

24. eddy current separator according to claim 23, characterized in that the partial cover (17) over the pole wheel (5, 14) is arranged.

25. Wirbelstromabscheider according to claim 23 or 24, characterized in that the partial cover (17) seen in the conveying direction behind the apex of the pumped medium (2), wherein the partial cover (17) preferably in the region between vertex and "o'clock position "is installed above the flywheel (5).

26. Eddy current separator according to one of claims 23 to 25, characterized in that the partial cover (17) is so flexible that it can avoid over-sized particles lying on the belt.

27. Eddy current separator according to claim 25 or 26, characterized in that the partial cover (17) has downwardly directed bristles.

28. Wirbelstromabscheider according to one of claims 23 to 27, characterized in that the lower end is less than 50mm above the pole wheel, preferably less than 25mm.

29. Eddy current separator according to one of the preceding claims, characterized in that the conveying medium is a conveyor belt.