This invention relates to a self propelled eddy current separating apparatus for separating non-ferrous metals from a feed material, and in particular for separating non-ferrous metals, such as aluminium, from waste during recycling.

Eddy current separation is based on the use of a magnetic rotor with rows of magnets having alternating polarity, spinning rapidly inside a non-metallic drum supporting a downstream end of a conveyor belt upon which waste material may be conveyed. As non-ferrous metals pass over the drum, the alternating magnetic field creates eddy currents in the non-ferrous metal particles, repelling the material away from the conveyor belt. While other materials drop off at the end of the conveyor belt, the non-ferrous metals are propelled forward over a splitter for separation. It is known to use eddy current separators to separate non-ferrous materials from waste during recycling. However, known devices are relatively large and heavy and therefore non-portable, typically forming part of a larger recycling system. Therefore their use has been restricted to recycling operations carried out off site at purpose built recycling facilities, whereby waste material must be transported to such facilities for sorting.

An object of the present invention is to provide a self propelled compact eddy current separating apparatus that can separate non-ferrous metals from other material on site, while being readily mobile on site and easily moved between sites when in a transport configuration.

According to a first aspect of the present invention there is provided a self propelled eddy current separating apparatus comprising a base and a separating conveyor mounted upon said base, said separating conveyor having a moveable conveying surface extending between a loading end and a discharge end thereof, a magnetic rotor being rotatably mounted at or adjacent the discharge end of the conveying surface of the separating conveyor, said magnetic rotor including a series of axially extending rows of magnets, the magnets in each respective row having a common polar orientation, the polar orientation of the magnets alternating from row to row, the magnetic rotor being driven to rotate about an axis extending transverse to the movable conveying surface such that material transferred on the conveying surface passes through a variable magnetic field, inducing eddy currents in any electrically conductive elements in the material, causing such electrically conductive elements to be repelled by the magnetic rotor and thus to be projected away from the conveying surface along a predictable trajectory, whereby electrically conductive elements in said material are projected from the conveying surface along said predictable trajectory to be received in a first receiving region, while non-electrically conductive elements in said material fall from the discharge end of the separating conveyor to be received in a second receiving region, wherein the base includes a wheeled or tracked chassis, a power unit being mounted on the base for powering the wheels or tracks.

Preferably a transversely extending splitter plate is located downstream of said separating conveyor, said splitter plate being located such that non-electrically conductive elements in said material fall from the discharge end of the separating conveyor on a first side of the splitter plate while electrically conductive elements in said material projected from the conveying surface along said predictable trajectory pass over a second side of said splitter plate, opposite said first side. The splitter plate may be adjustably mounted with respect to the separating conveyor. Preferably the splitter plate is mounted such that the position, angle and/or length of the splitter plate can be adjusted.

A first transfer conveyor may be provided having a loading end located in said first receiving region for receiving said electrically conductive elements of said material. The first transfer conveyor may extend transverse to said separating conveyor, a discharge end of the first transfer conveyor being located to one side of the base of the apparatus, whereby said electrically conductive elements of said material can be delivered into a suitable receptacle located beneath said discharge end of the first transfer conveyor.

A second transfer conveyor may be provided having a loading end located in said second receiving region for receiving said non-electrically conductive elements of said material. The second transfer conveyor may be located beneath said first transfer conveyor. The second transfer conveyor may extends substantially parallel to and/or be axially aligned with said separating conveyor. In an alternative embodiment, the second transfer conveyor may extend transverse to the separating conveyor, a discharge end of the second transfer conveyor being located on an opposite of the base of the apparatus to the discharge end of the first transfer conveyor. The second transfer conveyor may be located alongside and/or behind the first transfer conveyor.

The second transfer conveyor may deliver material to a stockpiling conveyor extending upwardly and outwardly from the base of the apparatus.

In one embodiment said stockpiling conveyor extends from one end of the apparatus. Alternatively the stockpiling conveyor may extend from a side of the apparatus.

A vibratory pan feeder may be located upstream of the separating conveyor, discharging onto a loading end of the separating conveyor. The pan feeder may comprise a downwardly inclined hopper having a discharge end feeding material onto the loading end of the separating conveyor and being mounted on the base via resilient mounts, vibration generating means being mounted on the pan feeder to impart vibratory motion to the pan feeder, whereby material delivered onto the hopper of the pan feeder is spread out and fed onto the separating conveyor with an even distribution across the width of the separating conveyor. In a preferred embodiment the power unit may be mounted beneath the pan feeder.

The power unit may comprise a diesel generator for generating electricity and/or hydraulic power to power the apparatus. Preferably said base includes a tracked chassis having a pair of ground engaging endless tracks located on respective lateral sides of the apparatus to enable the apparatus to move over uneven or unprepared surfaces. A wired or wireless remote control unit may be provided enabling the apparatus to be pedestrian controlled.

An operator platform may be located on at least one side of the base to provide operator access to the separating conveyor and/or to a control panel of the apparatus.

In one embodiment said separating conveyor may comprise a belt conveyor having an endless belt extending between first and second rollers or drums located at the upstream and downstream ends of the separating conveyor respectively, said magnetic rotor being mounted within the second roller or drum, said second roller or drum being formed from a non-metallic material.

A self propelled eddy current separating apparatus in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which :-

Figures 1 to 4 are perspective views of a self propelled eddy current separating apparatus in accordance with an embodiment of the present invention;

Figures 5 and 6 are side views of the apparatus of Figure 1 ;

Figures 7 and 8 are end views of the apparatus of Figure 1 ;

Figure 9 is a plan view of the apparatus of Figure 1 ;

Figure 10 is a perspective view the separating system of the apparatus of Figure 1 ; and

Figure 1 1 is a side view of the separating system of the apparatus of Figure 1 .

An eddy current separating apparatus in accordance with an embodiment of the present invention comprises a base defined by a self propelled tracked chassis 2, a horizontal primary belt conveyor 4 or separating conveyor being mounted on the base and having a flexible belt 6 guided over upstream and downstream guide rollers 8,10 respectively located adjacent loading and discharge ends of the conveyor 4 (see Figures 10 and 1 1 ) . A drive motor, such as an electric or hydraulic motor, may be provided for driving the primary conveyor 4, preferably via the upstream roller 8. Raised flexible side walls (not shown) may be provided adjacent each lateral side of the belt 6 to retain material upon the conveying surface of the primary conveyor 4.

A vibratory pan feeder 14 is provided upstream of the primary belt conveyor 4, discharging onto a loading end of the primary belt conveyor 4.

The pan feeder 14 comprises a downwardly inclined hopper 16 having a discharge end feeding material onto a magnetic drum separator 18. Non-ferrous materials fall to the front of the magnetic drum onto the primary belt conveyor 4. Ferrous materials fall to the rear of the magnetic drum onto the rear side stockpile conveyor 19. An adjustable splitter plate 20 is located immediately below the magnetic drum separator 18 to allow fine tuning of the separation of ferrous materials from non- ferrous materials. Alternatively such ferrous metal separation may take place upstream of the vibratory pan feeder.

The pan feeder 14 is mounted on the base via resilient mounts, such as springs. One or more eccentrically driven rotors 21 (see Figure 1 1 ) may be mounted on the pan feeder 14 to impart vibratory motion to the pan feeder 14, whereby material delivered onto the hopper 16 of the pan feeder 14 is spread out and fed onto the primary belt conveyor 4 with an even distribution across the width of the primary belt conveyor 4.

A power unit 22, such as an internal combustion engine, preferably a diesel generator, is mounted on the chassis 2 beneath the pan feeder 14 for providing electrical and/or hydraulic power for powering the tracks and the various electric motors provided on the apparatus for driving the various conveyors and other components of the separating apparatus. The power unit 22 may be adapted to generate electricity and a hydraulic power pack may be provided for providing hydraulic power, said hydraulic power pack being electrically driven via said power unit 22. Alternatively, the power unit 22 may be adapted to generate hydraulic power in addition to, or instead of, electrical power. Access doors 24 may be provided for providing access to the power unit 22 for maintenance. As illustrated in Figure 1 1 , a magnetic rotor 26 is rotatably mounted within the downstream guide roller 10 to be separately rotatable within the downstream guide roller 10 of the primary belt conveyor 4. The downstream guide roller 10 is made from a non-metallic material so as not to interfere with the magnetic field generated by the magnetic rotor 26. The magnetic rotor 26 includes a series of axial rows of permanent magnets (not shown), preferably comprising rare earth magnets, the magnets in each row having the same polar orientation as one another. The polar orientation of the magnets alternates from row to row. The magnetic rotor 26 may be adjustably mounted within the guide roller 10.

The magnetic rotor 26 is driven by an electric or hydraulic motor 12 to spin independently and at a much higher rate of speed than the non-metallic downstream guide roller 10 of the primary belt conveyor 4 within which it is mounted. The faster rotation of the rotor 26 and thus the alternate axial polarity rows of magnets relative to the speed of the primary belt conveyor 4, causes the material conveyed over the magnetic rotor 26 by the primary belt conveyor 4 to pass through a variable magnetic field, creating a circulating electrical current or "eddy current" in any electrically conductive elements in the material. The eddy currents produce a magnetic field that has a polarity that is the same as the polarity of the magnet(s) that induced the eddy currents. Since like magnetic poles repel on another, the electrically conductive elements in which the eddy currents are created are repelled and projected away from the rotor 26 along a predictable trajectory, thus repelling the electrically conductive non-ferrous metallic elements over a transversely arranged splitter plate 28 extending transversely to the primary belt conveyor 4 and located adjacent the discharge end of the primary belt conveyor 4. The non-ferrous metallic elements are thereby projected along said predictable trajectory over the splitter plate to pass onto a transversely arranged upper transfer conveyor 30, extending from one side of the apparatus, before being passed into a suitable receptacle, such as a skip, located beneath a discharge end of the upper transfer conveyor 30.

The remaining materials, such as plastics, glass, wood and other dry recyclables, free fall off the discharge end of the primary belt conveyor into a receiving chute 31 and onto a lower transfer conveyor 32, arranged beneath the upper transfer conveyor 30, separating them from the repelled non-ferrous metallic elements, before being delivered onto an upwardly directed stockpiling conveyor 34 to be delivered onto a stock pile. The lower transfer conveyor 32 is axially aligned with and/or extends substantially parallel to the primary belt conveyor 4 and the stockpiling conveyor 34 extends from one end of the apparatus. The angle of inclination of the stockpiling conveyor 34 may be adjustable.

Alternatively it is envisaged that the lower transfer conveyor 32 may extend transverse to the primary belt conveyor 4, in an opposite direction to the upper transfer conveyor 30, such that the stockpiling conveyor 34 may be located to one side of the chassis 2 to discharge to one side of the apparatus. In such case, the lower transfer conveyor 32 may be located alongside the upper transfer conveyor 30. The stockpiling conveyor 34 and lower transfer conveyor 30 may be formed as a single belt conveyor.

The primary belt conveyor 4 transports material to be screened over the rotating magnetic rotor 26 at the discharge end of the primary belt conveyor 4. As discussed above, as the material passes over the magnetic rotor 26, eddy currents are induced in the non-ferrous metallic elements contained therein. The eddy currents generate an electromagnetic force which repel the non-ferrous metallic elements from the magnetic rotor 26. This force affects the trajectory of the non-ferrous metallic elements, allowing the splitter plate 28 to be positioned to separate the metallic and non-metallic material streams.

The splitter plate 28 may be adjustably mounted to allow the position (in particular height), angle and/or length of the splitter plate 28 to be adjusted to suit the particle size of the non-ferrous metallic material to be separated, which affects the trajectory of such material.

The self propelled tracked chassis 2 allows for movement of the apparatus over uneven or unprepared surfaces, allowing the apparatus to be readily moved around on site, as required. The apparatus may be provided with a control panel 36 housing a control system for controlling the operation of the apparatus. The control panel may be located at the rear of the machine or at other desired location. In one embodiment a mode selection key switch may be provided for selection of an operation mode, such as :- i. Machine move

ii. Machine set-up

iii. Manual control

iv. Screening

Two options for control of the apparatus may be available:-

Option 1 - Pushbutton

Illuminated pushbuttons may be provided on the control panel 36 for operation of the machine. Speed control pots may be provided for the setting of the speed of variable speed motors for controlling the speed of the respective conveyors and the magnetic rotor. An operator platform 38 and guard rail 40 may be provided to facilitate operator access to the control panel 36 and/or the primary belt conveyor 4.

Option 2 - Human Machine Interface (HMI)

The pushbutton functions may be replaced as far as possible with an HMI / PLC (programmable logic controller). A control pendant may be connected to the control panel 36 via a trailing lead or a wireless remote control unit may be provided for pedestrian control of the machine for movement around the site. Either the pendant control or wire remote may be used for control of the machine by an operator. Alternatively it is envisaged that the apparatus may include a control cab for housing an operator. However, it is preferred that the apparatus is dimensioned to fit inside a standard shipping container, therefore pedestrian control may be preferred.

One or both of the upper and lower transfer conveyor 30,32 and/or the stockpiling conveyor 34 may be arranged to be removed, folded and/or telescopically retracted to allow the apparatus to fitted within a shipping container during transportation and/or to allow the apparatus to be loaded onto a suitable flat bed trailer.

The invention is not linnited to the embodinnent(s) described herein but can be amended or modified without departing from the scope of the present invention.