EP0388626A1 - Apparatus for separating non-magnetisable metals from a mixture of solids - Google Patents

Abstract

The mode of operation of a device for separating non-magnetizable metals, in particular non-ferrous metals, from a solid mixture by means of an alternating magnetic field can be improved and the device can be structurally simplified by the magnetic field generator (15) next to a straight and / or curved and / or kinked slideway (4 ) is arranged from an electrically poorly conductive material.

Description

The invention relates to a device for separating non-magnetizable metals, in particular non-ferrous metals, from a solid mixture by means of a magnetic field generator.

With the aid of such a device, the so-called eddy current separation can be carried out. The feed material is guided over the poles of an alternating magnetic field generator, for example on a belt or in free fall. In this case, eddy currents are induced in the electrically conductive components of the mixture, which build up their own magnetic fields opposing the generator field and thereby accelerate these components by electromagnetic forces relative to the other components of the mixture. Eddy current separation allows non-ferromagnetisable, electrically highly conductive substances, such as aluminum and copper, to be separated from non-ferrous solid mixtures and non-ferrous metal / non-metallic solid mixtures, such as car shredder rubble or electronic scrap. If ferromagnetic parts are contained in these materials, the eddy current separation can be preceded by a magnetic separation in order to remove ferromagnetic parts beforehand. Other sor animal and classification stages upstream, because the greatest possible pre-enrichment and fractionation of the added solid mixture have a positive effect on the separation success.

In a separating device known from DE-OS 34 16 504, a solid mixture for separating the ferromagnetic portion is first passed by means of a conveyor belt below a magnetic separator and then fed from the conveyor belt to a slowly rotating outer drum for separating the non-ferrous metals. A fast rotating rotor equipped with permanent magnets is arranged concentrically inside the outer drum. The permanent magnets extend uniformly parallel to the rotor axis and are arranged at a large distance from one another so that the magnetic field which forms between the poles of the permanent magnets acts as far as possible outside the drum. With this device, in comparison to other eddy current separation processes, higher throughputs with greater layer heights of the solid mixture should be possible in that the separating forces of the alternating magnetic field act on the solid mixture at the point in time at which gravity is not yet or only slightly effective.

In this known device, however, mutual hindrance occurs when the material parts pass into their throwing parabola beyond the drum radius. On the one hand, conductive parts to be deflected are braked by the non-conductive parts and, on the other hand, non-conductive parts are undesirably accelerated by contact with the conductive non-ferrous metal parts. As a result, incorrect discharges cannot be avoided in both products, ie in the collection area of the non-ferrous Metal parts also get electrically non-conductive parts and vice versa. Apart from this, the placement of the magnetic rotor in the cavity of the drum presents considerable problems; these relate to both the design and the manufacturing costs. The magnetic rotor must namely be stored in the confined space within the drum, which cannot be enlarged in diameter, preferably rotatable, the storage becoming even more complicated when the magnetic rotor is to be adjustable, for example concentrically on a radius around or on a curve with different radial distances from the drum axis of rotation.

In addition, the drum is difficult to manufacture or process and requires extremely precise manufacture, with the aim of achieving thin, uniform drum wall thicknesses with high mechanical stability so that as little magnetic force as possible is lost; For example, no different material hardnesses must be allowed in the surface of the drum, i.e. no softer and harder points occur, so that the only slight air gap between the magnet rotor and the drum can be partially reduced so that serious damage due to frictional contact between the magnet rotor and the drum cannot be excluded.

The invention has for its object to provide a device that is structurally simple and allows a better separation of non-ferrous metals in particular from a mixture of solids.

This object is achieved in that the magnet according to the invention in a device of the type mentioned field generator is arranged next to a rectilinear and / or curved and / or kinked slideway made of an electrically poorly conductive material. The expression "poor electrical conductivity" takes into account that, according to scientific understanding, all materials are electrically conductive; a distinction is only made between better or poorer conductive materials, the conductivity of the latter practically going to zero (cf. page 522 from "Taschenbuch Elektrotechnik", Volume 1, Carl Hanser Verlag). The invention is based on the finding that, with a slideway arranged above a magnetic field generator, the shape and curvature of which can be structurally adjusted by simple means in comparison with a rotating drum in such a way that an optimized effect of the eddy current separation can be achieved. In addition, due to the comparatively easy to manufacture slideway and the possible elimination of the rotating drum, which requires complex storage, both the system and the manufacturing and assembly costs are significantly reduced. The magnetic field generator, which is either stationary but preferably adjustable in its installed position, can be arranged in such a way that the full force of the magnetic field floods the non-ferrous metals sliding in the area of the slideway in the area referred to below as the "material discharge zone"; The material discharge zone is reached when the material to be separated just falls due to gravity on the curved surface formed either directly by the slideway or preferably a conveyor belt wrapping around the slideway, so that the mechanical ejection forces combine with the latest possible forces of the magnetic field for the non-ferrous metals results in the greatest deflection of the throwing parabola and thus a deliberate separation from the other mixture components. To generate the alternating magnetic field a magnetic rotor or alternatively an electrically excited magnetic field generator in the form of a fixed magnet system fed with AC voltage can advantageously be used.

The slideway of a stationary, preferably designed as a segment of a hollow cylinder and advantageously having a housing encapsulating the magnetic field generator, which is very variable, deviating from the circular shape, possibly endless radius of curvature below the slideway allows a large free space usable for structural purposes, but without the space requirement to increase the system or eddy current separating device, as would be the case with a slightly larger drum diameter in relation to the radius of curvature possible with a slideway according to the invention. Apart from the fact that a curvature may also have a straight line, the slideway can be formed, for example, from one or more differently curved cam tracks and / or straight lines with kinks. Finally, the magnetic field generator in the form of a magnetic rotor does not need to be stored in a likewise rotating drum, but can be stored, for example, in the side walls of the housing, which consists of an antimagnetic and electrically non-conductive material. The housing encapsulating the magnet rotor protects in particular the air gap between the magnet rotor and the slideway from splash water and dust, in particular Fe dust, which increases the rotor diameter, and thus prevents the air gap from becoming clogged, which leads to friction with the inside of the slideway and thus causing overheating.

A mutual hindrance of the parts of the mixture of solids to be separated can almost be ruled out if the mixture to be separated is transported as far as possible beyond the apex of the slideway without interfering influences and on the other hand the repulsive forces then have the greatest effect on the non-ferrous metals when the mixture is just still in the material discharge zone, the magnetic field generator adjustable according to the invention both radially and in the circumferential direction covering an adjustment range which meets all operating requirements. The solid mixture can be fed, for example, by means of a separate conveyor ending above the slideway to the desired area far above the apex of the slideway in which the material falls straight due to gravity.

According to a preferred embodiment, however, the solid mixture is fed from a conveyor belt which is guided over the slideway and to which two deflection drums are preferably also assigned. If the deflection drum at the front in the transport direction of the conveyor belt is driven, lower forces are required due to the then pulled conveyor belt than that when driving the rear conveyor belt in the transport direction, i.e. arranged in the feed area of the solid mixture, then pushing the conveyor belt deflection drum would be the case. In addition, lower frictional forces occur when driving the front deflection drum, since essentially only the friction in the area of the slideway can be overcome, which should consist of a low-friction, non-metallic material.

It is recommended that the front pulley is adjustable. In this way, the preload influence the conveyor belt and achieve a large wrap angle and thus a higher frictional engagement of the pulling, front pulley. Alternatively, the pretensioning of the conveyor belt can be changed using a tension roller.

If the front deflection drum is designed as a magnetic reel, it is possible to separately sort out iron components at this point, especially if the iron separation was not carried out or only insufficiently before the eddy current separation.

According to an advantageous embodiment, the horizontal upper run of the conveyor belt rests on a sliding surface. A sliding belt conveyor can thus be achieved in which the conveyor belt from the material feed point in the area of the rear deflection drum in the transport direction to the front end of the sliding track, i.e. far beyond the material drop zone on a support that also supports the conveyor belt. As material for the preferably in the form of a trough, i.e. Materials designed with side walls and bridging the distance from the rear deflection drum to the slideway are all suitable materials which ensure good gliding behavior, but are not electrostatically charged, such as, for example, antimagnetic stainless steel, plastic or glass. In the case of a trough-like sliding surface, the side or side walls prevent material from falling off the conveyor belt on its way from the feed point to the slide. The trough also supports the guidance of the conveyor belt.

According to a further embodiment, there is a space in the space below the slideway and above the magnetic rotor Axially extending in the direction of transport, preferably made of magnetically good and electrically poorly conductive material guide body arranged in the magnetic field of the magnetic rotor or magnetic field generator. A guide body, which should be made of an electrically poorly but magnetically highly conductive material, for example ferrite, to avoid eddy current losses is understood to mean a body, such as a flat or curved plate, which deflects the field lines of the magnetic field generator and detects a magnetic connection below, made possible and reinforced towards the magnetic field generator. The field lines of the magnetic field generator should thus be directed and the magnetic field channeled. Experiments have confirmed that the magnetic field acts on the mixture of solids long before the apex is reached and the material components perform relative movements at an early stage, so that the alternating magnetic field cannot influence these parts when the apex or the material discharge zone is reached , which affects the separation effect. Due to the stationary slideway with a large radius of curvature, there is - without increasing the overall system size and without the mechanical problems compared to a rotating drum - a free space under the slideway which is sufficient, in addition to the magnetic field generator, preferably one to accommodate guide bodies that are adjustable both in and against the conveying direction. The adjustment of the guide body enables adjustments to the respective position of the magnetic field generator.

If the guide body, advantageously starting from the rear end of the slideway in the transport direction, extends to the front, it can be achieved that the supplied fest The mixture of substances remains calm on the conveyor belt, ie without being disturbed by the magnetic field, until it has reached the apex of the slideway and the subsequent material discharge zone, in which the full force of the magnetic field floods the non-ferrous metals.

According to a further embodiment, a straightening body is arranged at a distance above the curvature of the slideway in the magnetic field of the magnetic field generator. This preferably consists of magnetically good and poorly electrically conductive material. Under a straightening body, which can be a flat or curved plate, for example, a field line generated by the magnet rotor is aligned in the direction of its surface, i.e. attractive object understood; the field lines can thus be concentrated in such a way that a maximum force effect of the magnetic field on the non-ferrous metals in the area of the material discharge zone is also promoted in this way.

A straightening body that can be adjusted is advantageous. If the straightening body is both radially adjustable and is arranged on a radius to pivot about the axis of rotation or the pivot point of the magnetic field generator, its distance from the slideway or from the magnetic field generator can be adapted to the fractions contained in the solid mixture, this distance being one and a half should be up to three times the largest grain diameter of the processed material; it can also be swiveled exactly into the area of the material drop zone.

The width of the guide body and the straightening body is preferably equal to the width of the magnetic field generator. The force effect of the magnetic field can thus be optimized over the entire area of the material discharge zone.

It is recommended that the guide and straightening bodies are cooled, for which purpose these components can have cooling fins and / or cooling pipelines through which oil flows, for example. Excessive heating of the straightening and / or guiding body due to the eddy current flow can thus be avoided.

• Fig. 1 eine Wirbelstromscheidevorrichtung mit einer er­findungsgemäßen Gleitbahn in der Abscheidezone oberhalb eines dort angeordneten Magnetfelderzeu­gers in Form eines Magnetrotors, in schematischer Seitenansicht;
• Fig. 2 den gemäß Fig. 1 neben der Gleitbahn gelagerten Magnetrotor, in der Seitenansicht als Einzelheit vergrößert dargestellt; und
• Fig. 3 einen Querschnitt durch eine der Gleitbahn gemäß Fig. 1 vorgeschaltete, als Trog ausgebildete Gleitfläche für einen Fördergurt.

The invention is explained in more detail below with reference to the embodiment shown in the drawings. Show it:

• 1 shows an eddy current separating device with an inventive slideway in the separation zone above a magnetic field generator arranged there in the form of a magnetic rotor, in a schematic side view;
• FIG. 2 shows the magnetic rotor mounted next to the slideway according to FIG. 1, enlarged in detail in the side view; and
• Fig. 3 shows a cross section through a slide surface upstream of the slide path according to Fig. 1, designed as a trough for a conveyor belt.

In a system with a belt conveyor which is preferred in the context of the eddy current separating device according to the invention, a solid mixture containing nonferrous metals is fed from a feed conveyor (not shown), for example a vibrating trough, to a conveyor belt 2 at the end of the feed 1. The conveyor belt 2 rotating in the direction of transport 3 (see the arrow) wraps around a quarter hollow at the front end in the direction of transport 3 Cylinder segment formed slideway 4; In addition, the conveyor belt 2 is deflected by a rear pulley 5 arranged at the feed end 1 and a front, driven pulley 6 (drum motor). The slideway 4 is connected upstream of the distance from the rear deflection drum 5 to the joint 7 of the rear end of the slideway 4 in the direction of transport 3, designed as a trough 8 with side walls 9 according to FIG. 3. The sliding surface 10 or the trough 8, in conjunction with the seamlessly adjoining, shell-like sliding path 4, enable sliding guidance and support of the upper run 11 of the conveyor belt 2; the side walls 9 of the trough 8 prevent material abandoned on the conveyor belt 2 from falling on the way from the end of the feed 1 to the joint 7. As is shown schematically in FIG. 1 for the deflection drums 5, 6, the belt conveyor is anchored to the foundation 13 by means of supports 12.

In addition to the slideway 4, below the level of the conveyor belt 2, a magnetic rotor 15, which is preferred as a magnetic field generator in the context of the invention, is mounted in a rocker arm 16 about the pivot point 17 of which it can be pivoted in the direction of the double arrow 18; In addition, the magnet rotor 15 is arranged radially adjustable in the direction of arrow 19, so that it can be pivoted on any curved tracks. As is shown in detail in FIG. 2, the magnet rotor 15 has rows of permanent magnets 22 which extend in the longitudinal direction of the rotor shaft 20 and are fastened in the base body 21 with alternating north-south polarity; Always select a number of poles that allows an alternating type of pole. The position of the rotor shaft 20 below the slideway 4 in the housing 14 and thus the effective range of the permanent magnets 22 can in the discharge zone which is approximately delimited by the vertical 23 and the horizontal 24 and which defines the area in which the solid mixture lying on the conveyor belt 2 falls due to the force of gravity. The air gap 25 between the magnet rotor 15 and the inner surface of the slideway 4 is the smallest in this region, which also has the material discharge zone 26 and is indicated by the dash-dotted lines.

The mixture transported by means of the conveyor belt 2 far beyond the vertical 23, far into the region of the drop zone, is already in a throwing parabola 27, for which due to the material drop zone 26 corresponding to the optimal effect of the magnetic rotor 15 Line of action 28 lies, the fully effective force of the eddy current results in a curve lying furthest outwards with a correspondingly strong deflection of the non-ferrous metals. The non-ferrous metals deflected in accordance with the throwing parabola 27 fall into a collecting container, not shown, which is removed from the collection point for the other mixture components. The separation into valuable non-ferrous metals and the other components is supported by means of a separating saddle 29 which can be adjusted with its apex in a substantially horizontal direction. According to arrow 30, the latter components drop essentially without deflection and, viewed in the direction of transport 3, reach an area in front of the separating saddle 29.

The sliding guide of the conveyor belt 2 in the area of the magnetic rotor 15 by means of the stationary slideway 4 designed as a quarter-hollow cylinder segment, via which the conveyor belt 2 is pulled by the driven deflection drum 6. creates sufficient space below the slideway 4 in the housing 14 to arrange a guide body 31 therein, for example rigidly connecting it to the side walls of the housing 14. The guide body 31 extends above the magnet rotor 15 axially in the direction of transport 3 and enables a magnetic connection downwards, back to the magnet rotor 15, ie the field lines of the alternating magnetic field generated by the magnet rotor 15 are specifically directed and channeled. This prevents the magnetic field from influencing the solid mixture lying on the conveyor belt 2 in the area between the joint 7 and the vertical 23; the constituents of the solid mixture thus remain calmly on the conveyor belt 2 until they have reached the curvature area of the slideway 4 and are there exposed to the greatest magnetic force in the material discharge zone 26.

The quality of the separation effect, in particular if fractions of small grain size are present in the solid mixture supplied, is further improved by a straightening body 32, which is located above the curvature of the slideway 4, and - like the guide body 31 - over the entire width of the Magnet rotor 15 extends. The straightening body 32 namely causes the field lines of the alternating magnetic field generated by the magnetic rotor 15 to extend to the straightening body 32, which attracts the field lines and concentrates them in the desired manner.

Claims (24)

1. Apparatus for separating non-magnetizable metals, in particular non-ferrous metals, from a solid mixture by means of an alternating magnetic field, characterized in that the magnetic field generator (15) in addition to a straight and / or curved and / or kinked slideway (4) from an electrically poorly conductive Material is arranged. 2. Device according to claim 1, characterized in that the slideway (4) is curved deviating from the circular shape. 3. Apparatus according to claim 1, characterized in that the slideway (4) is designed as a segment of a hollow cylinder. 4. The device according to one or more of claims 1 to 3, characterized by a magnetic rotor (15) as a magnetic field generator. 5. The device according to one or more of claims 1 to 4, characterized in that the slideway (4) is part of a housing (14) encapsulating the magnetic field generator (magnetic rotor 15). 6. The device according to one or more of claims 1 to 5, characterized in that the position of the magnetic field generator (magnetic rotor 15) is adjustable. 7. The device according to one or more of claims 1 to 6, characterized in that a conveyor belt (2) is guided over the slideway (4). 8. The device according to claim 7, characterized by two the conveyor belt (2) deflecting drums (5, 6). 9. The device according to claim 8, characterized in that the in the transport direction (3) of the conveyor belt (2) front deflection drum (6) is driven. 10. The device according to claim 8 or 9, characterized in that the front deflection drum (6) is adjustably mounted. 11. The device according to one or more of claims 8 to 10, characterized in that the front deflection drum (6) is designed as a tape reel magnetic separator. 12. The device according to one or more of claims 1 to 11, characterized in that the horizontal upper run (11) of the conveyor belt (2) rests on a sliding surface (10). 13. The apparatus according to claim 12, characterized in that the sliding surface (10) is designed in the form of a trough (8). 14. The apparatus according to claim 12 or 13, characterized in that the sliding surface (10) bridges the distance from the rear deflection drum (5) to the slideway (4). 15. The device according to one or more of claims 1 to 14, characterized in that one in the space below the slideway (4) and above the magnetic rotor (15) axially in the transport direction (3) extending guide body (31) in the magnetic field of the magnetic field generator (Magnet rotor 15) is arranged. 16. The apparatus according to claim 15, characterized in that the guide body (31) consists of magnetically good and electrically poorly conductive material. 17. The apparatus according to claim 14 or 15, characterized in that the guide body (31) extends from the rear in the transport direction (3) region of the slideway (4) to the front. 18. The apparatus according to claim 16 or 17, characterized in that the guide body (31) in and against the conveying direction (3) is adjustable. 19. The device according to one or more of claims 1 to 17, characterized in that a straightening body (32) is arranged at a distance above the curvature of the slideway (4) in the magnetic field of the magnetic field generator (magnetic rotor 15). 20. The apparatus according to claim 19, characterized in that the straightening body (32) is adjustable. 21. The apparatus according to claim 19 or 20, characterized in that the straightening body (32) consists of magnetically good and electrically poorly conductive material. 22. The device according to one or more of claims 15 to 21, characterized in that the width of the guide and the directional body (31 or 32) is equal to the width of the magnetic field generator (magnet rotor 15). 23. The device according to one or more of claims 19 to 22, characterized in that the straightening body (32) is a rotor rotating at approximately the speed of the conveyor belt (2). 24. The device according to one or more of claims 15 to 23, characterized in that the guide and / or the straightening body (31 or 32) are cooled.

Images