Separation Apparatus and Method; Apparatus and Method for Bringing Articles in a Layer

Abstract

A separation apparatus is disclosed, comprising: a layerizer arranged to bring a group of particles in a layer on a transport surface with a constant spatial relation of the particles relative to each other in the layer; an identifier arranged to identify particles in the group of particles that have a specific property; a separator arranged to separate the particles in the group based on a difference in affinity between the particles and the separator; an affinity modifier arranged to modify said affinity for identified particles relative to non-identified particles in the group. The layerizer comprises a recirculating transport surface on which the particles of the layer are carried. The transport surface is arranged to move along a transport trajectory as a rigid plane. Further, a method for separation of particles from a group of particles is disclosed.

Claims

1. A separation apparatus, comprising: a layerizer arranged to bring a group of particles in a layer on a transport surface with a constant spatial relation of the particles relative to each other in the layer; an identifier arranged to identify particles in the group of particles that have a specific property; a separator arranged to separate the particles in the group based on a difference in affinity between the particles and the separator; an affinity modifier arranged to modify said affinity for identified particles relative to non-identified particles in the group; wherein the layerizer comprises a recirculating transport surface on which the particles of the layer are carried along a transport trajectory, wherein the transport surface is arranged as a rigid plane so as to limit movement of the particles transverse to the transport trajectory.

2. The separation apparatus of claim 1, wherein the transport surface is arranged to rotate.

3. The separation apparatus of claim 2, wherein the transport surface is a mantle surface, in particular a rotating mantle surface of a drum.

4. The separation apparatus according to claim 1, wherein the transport trajectory includes a particle delivery zone where the particles disengage the transport surface to become airborne and travel along a flight path to the separator.

5. The separation apparatus according to claim 4, wherein the particle delivery zone includes a part of the transport trajectory where the transport surface moves downward.

6. The separation apparatus according to claim 1, wherein the transport trajectory includes a particle pickup zone where the particles engage the transport surface.

7. The separation apparatus according to claim 6, wherein the particle pickup zone includes a part of the transport trajectory where the inside of the mantle surface passes along a zone were air pressure is arranged to be lower than at the outside of the transport surface, and where particles are sucked onto the transport surface by ambient air passing through apertures in the transport surface.

8. The separation apparatus according to claim 1, wherein the layerizer comprises a fluidized bed of particles that is maintained along a part of the transport trajectory, in particular at a particle pickup zone where the particles engage the transport surface.

9. The separation apparatus according to claim 1, wherein the transport surface is provided with a plurality of apertures for passing air therethrough.

10. The separation apparatus according to claim 1, wherein the transport surface is a mantle surface that is arranged to rotate about a stationary support core of a drum.

11. The separation apparatus according to claim 1, wherein the transport trajectory includes an identification zone where the transport trajectory extends along the identifier.

12. The separation apparatus according to claim 1, wherein the separator comprises a catch surface on which identified particles in are caught, preferably a recirculating catch surface.

13. The separation apparatus according to claim 12, wherein the catch surface is a mantle surface that is arranged to rotate as a rigid plane.

14. The separation apparatus according to claim 1, wherein the affinity modifier modifies the affinity of the identified particles for the catch surface by applying affinity modifying particles to the identified particles, in particular to increase the affinity between the identified particles and the catch surface.

15. The separation apparatus according to claim 1, wherein the affinity modifier modifies the affinity of the catch surface for the identified particles by applying affinity modifying particles to the catch surface of the separator, in particular corresponding to that particles' position in the layer on the transport surface.

16. The separation apparatus according to claim 14, wherein the affinity modifying particles form a layer onto the identified particles or the catch surface.

17. The separation apparatus according to claim 14, wherein the affinity modifying particles include or are liquid droplets.

18. The separation apparatus according to claim 17, wherein the liquid droplets comprise water to form a moisture bridge between the identified particles and the separator.

19. The separation apparatus according to claim 1, wherein the affinity modifier comprises a printer head.

20-22. (canceled)

23. A method for separation of particles from a group of particles, comprising the steps of: providing a group of particles that comprises particles with different properties, e.g. material, color, shape and/or size; supplying the group of particles to a transport surface that moves along a transport trajectory as a rigid plane so as to bring the group of particles in a layer with a constant spatial relation on the transport surface; identifying particles in the group of particles that have a specific property; modifying an affinity between the identified particles and a separator relative to that affinity between non-identified particles and the separator using an affinity modifier; separating the particles in the group based on their difference in the affinity with the separator.

24. The method according to claim 23, further including casting the particles off the transport surface to become airborne and travel along a flight path to a catch surface of the separator.

25. The method according to claim 24, further including modifying the affinity of the identified particles by applying affinity modifying particles to the identified particles and/or the catch surface to increase the affinity between the identified particles and the catch surface.

26-45. (canceled)

Description

[0070] The invention will be further elucidated on the basis of an exemplary embodiment which is represented in a drawing. In the drawings:

[0071] FIG. 1 shows a schematic view of a first embodiment of the separation apparatus.

[0072] FIG. 2 shows a second schematic view of a second embodiment of the separation apparatus.

[0073] It is noted that the figures are merely schematic representations of a preferred embodiment of the invention, which is given here by way of non-limiting exemplary embodiment. In the description, the same or similar part and elements have the same or similar reference signs.

[0074] In FIG. 1 is shown a first embodiment of a separation apparatus 1 comprising an identifier 2 arranged to identify the particles 3 in a group of particles 4 that have a specific property. A specific property that is measured or otherwise assessed by the identifier 2 may e.g. be a type of material, weight, color, shape and/or size.

[0075] The separation apparatus 1 is arranged for individual engagement of particles. The particles may be small particles such as shredded PE, PP or PET of different colors or different grades with a diameter size that may range between 1-20 mm.

[0076] A separator 7 is provided that is arranged to separate the particles in the group 4 based on a difference in affinity between the particles and the separator 7. The separator 7 has a catch surface 12 onto which identified particles 3 adhere such that they can be separated from the group particles 4.

[0077] An affinity modifier 5 is provided that is arranged to modify said affinity for identified particles 3 relative to non-identified particles 6 in the group.

[0078] The sensor separation apparatus 1 comprises a recirculating transport surface 9 on which particles 4 are carried. The recirculating transport surface 9 here forms part of a layerizer 8 that is arranged to bring the group of particles 4 in a layer. It provides the particles 4 in the layer on the recirculating transport surface 9 with a known constant spatial relation in the layer between at least the identifier 2 and the affinity modifier 5. The transport surface 9 is arranged to move along a transport trajectory 20 as a rigid plane. The rigid plane is formed by the mantle surface 21 of a transport drum 22 that rotates about a center axis of the drum 22 in the direction of arrow P1. The drum comprises a core 23, which supports the mantle surface 21. The support core may close off the mantle surface at the sides, so as to complete a chum shape. In this embodiment, the mantle surface 21 rotates about the core 23. It shall be clear that it is also possible to embody the transport drum 22 so that the mantle surface 21 rotates together with the core 23. The transport surface 9 is here provided with a plurality of apertures 24 for passing air therethrough, and may in particular be a wire mesh that is supported stiffly on the stationary core 23 of the transport drum 22 to be able to rotate as a rigid plane. In particular, the mantle surface 21 is a rigid plane in that it is kept from bending about an axis that extends along the axis of rotation of the transport drum 22. The apertures 24 in the wire mesh are sized smaller than the particles, so that the particles cannot pass through the apertures.

[0079] In this embodiment, both the identifier 2 and the affinity modifier 5 are located along the transport trajectory 20, in particular above the transport trajectory. Due to the mantle surface 21 recirculating rigidly about the center axis, and e.g. not needing to flex to round a divert wheel, the distance between any two points on the transport surface 9 can stay substantially constant. This way, it can be ensured in practice that the position, speed and the travel time of an identified particle 3 from the identifier 2 along the transport trajectory 20 to the affinity modifier 5 is known. This allows operation of the identifier 2 and the affinity modifier 5, and optionally also the separator 7 to be synchronized with high precision.

[0080] The layerizer 8 in this embodiment comprises a transport surface 9 on which the particles are deposited in a planar layer. As shown in FIG. 1 the group particles 4 are fed onto the mantle surface 21 of the transport drum 22 that forms the recirculating transport surface 9 by a feed device 25. The feed device 25 forms part of the layerizer 8. The group particles 4 may be fed by such feed device 25 onto the transport surface 9 as a continuous curtain of particles or as sections with a predetermined distance. As shall be discussed further on in more detail, in this example the feed device 25 includes a fluidized bed 26 of particles 4 to ensure that the mantle surface 21 of the transport drum 22 is covered with particles 4 in a monolayer that has a thickness of only one particle.

[0081] The identifier 2 is in FIG. 1 embodied as an optical sensor 10 that is positioned above the transport surface 9 to identify the group particles 4 that have a specific property. For example, the identifier 2 is arranged to identify the color of the particles 4 in a stream of clear and in particular translucent particles. The identifier 2 is also arranged to identify a specific type of PP via a marker and/or additive provided in the PP material. Furthermore, the identifier 2 is arranged to identify the position of the particles on the transport surface 9.

[0082] After the particles 4 have passed along the identifier 2, the affinity modifier 5 in this example modifies the affinity of the identified particles 3 by applying affinity modifying particles 11 directly to the identified particles 3. The modifying particles 11 are here discharged from above the transport surface 9 such that the affinity modifying particles 11 form a layer onto the identified particles 3. The affinity modifying particles 11 are here discharged with a component of their velocity parallel to the motion of the transport surface 9. In this way, it may be avoided that identified particles 3 are missed by the particles by time of flight effects related to variations in the height of the identified particles above the transport surface 9.

[0083] The affinity modifying particles 11 may in FIG. 1 be liquid droplets and/or powder particles. The liquid droplets in this example are water droplets to moisturize the identified particles to form a moisture bridge between the identified particles 3 and the separator 7. The water may be provided with a minor amount of additives to improve the electrical conductivity. A reason for this is that some printers require the liquid to be disposed to have a certain electrical conductivity for properly discharging the liquid. This applies not only to ink, but also to water in case water is to be discharged by the printer. Optionally, it also possible that after the identified particles 3 have been moisturized by liquid droplets, a second modifier (not shown) or the same modifier discharges a second material, preferably powder particles. The powder particles in FIG. 1 may be magnetic or magnetizable powder particles, e.g. industrial ferrosilicon wherein they are preferably spherically shaped such that the identified particles 3 may be engaged individually and/or lifted by the separator 7.

[0084] The affinity modifier 5 is in FIG. 1 embodied as a printer head for distributing water or another liquid for moisturizing the liquid droplets. The printer head 5 is arranged for providing droplets smaller than 100 micron, preferably 30 to 60 micron. The droplets are preferably provided at a resolution of at least 100 droplets per inch—or 39 to 40 droplets per centimetre. At this resolution, it is possible to deposit liquid only on identified particles 3. Additionally to this, powder particles may be discharged on either identified particles 3 only or on all particles. On identified particles 3, powder particles are bound by the liquid on the identified particles 3. Powder particles on other particles 6 may be removed, for example by means of blowing or a magnetic field. Alternatively, in an embodiment in which liquid as well as powder particles are discharged, liquid is deposited at all particles 4 on the conveying surface 9 and the powder particles are only discharged on the identified particles 3.

[0085] If identified particles are moisturized, this may be done in a blanket fashion, deploying a blanket or substantially continuous film of liquid on either all particles 4 or identified particles 3. Alternatively, liquid is discharged on specific areas. This may for example be established by depositing the liquid in lines. These lines may be parallel to the motion of the transport surface, perpendicular to the motion of the transport surface, or under an angle relative to the motion of the transport surface.

[0086] In certain embodiments, it may be desired to pretreat the particles 4 for improving adherence between affinity modifying particles and the group particles 4. To this purpose, a pre-treatment module (not shown) may be provided for pretreating the group particles 4. If the affinity modifying particles comprise water, it may be preferred to improve hydrophilic properties of the group particles 4. In one specific embodiment, a very thin layer (1 to 10 nanometers) of calcium carbonate is applied to the group particles. Such layer of calcium carbonate may be applied by exposing the group particles to water having a sufficiently high hardness (measured, for example, in German degrees) at a temperature of at least 80 degrees centigrade. Exposure may be provided by means of spraying or submersion. Submersion is preferably done for at least 30 seconds, in water of sufficient hardness, at a temperature of at least 80 degrees. Alternatively or additionally, a coating of for example hexamethyldisilazane and/or other hydrophilic substances may be provided as a coating for the group particles 4. The coating may be applied on all particles or on identified particles 3 only. Alternatively, a hydrophobic coating may be applied, e.g. to non-identified particles.

[0087] Thus, a separation apparatus 1 is disclosed, comprising: a layerizer 8 arranged to bring a group of particles 4 in a layer on a transport surface 9 with a constant spatial relation of the particles relative to each other in the layer; an identifier 2 arranged to identify particles 3 in the group of particles 4 that have a specific property; a separator 7 arranged to separate the particles in the group 4 based on a difference in affinity between the particles and the separator 7; an affinity modifier 5 arranged to modify said affinity for identified particles 3 relative to non-identified particles 6 in the group of particles 4. The layerizer 8 comprises a recirculating transport surface 9 on which the particles of the layer are carried. The transport surface 9 is arranged to move along a transport trajectory 20 as a rigid plane.

[0088] As can be seen in FIG. 1, the transport trajectory 20 includes a particle delivery zone 13 where the particles disengage the transport surface 9 to become airborne and travel along a flight path 14 to the separator 7. The particle delivery zone 13 includes a part of the transport trajectory 20 where the transport surface 9 moves downward. At the delivery zone 13, the particles are cast off of the transport surface 9 due to their inertia.

[0089] The transport trajectory 20 further includes a particle pickup zone 15 where the particles engage the transport surface 9. The particle pickup zone 15 includes a part of the transport trajectory 20 where the inside of the mantle surface 21 passes along a zone 16 were air pressure is arranged to be lower than at the outside of the transport surface 9, and where particles are sucked onto the transport surface 9 by ambient air passing through apertures 24 in the transport surface 9. The zone 15 with reduced air pressure is embodied as a vacuum chamber in the stationary core 23 of the transport drum 22. In this embodiment, the transport trajectory 20 further includes an identification zone where the transport trajectory 20 extends along the identifier 2.

[0090] The layerizer 8 comprises as feeder device 25 a fluidized bed 26 of particles that is maintained at the particle pickup zone 15. The particles are sucked onto the transport surface 9 from the fluidized bed 26. The fluidized bed 26 is arranged in an air gap 17 that extends at the particle pickup zone 15 between the transport surface 9 and a guide 18. The guide 18 extends along a segment of the transport surface 9, and comprise apertures 19 for passing air therethrough. The layerizer 8 further includes a vibrating feed plate 27 to feed particles into the air gap 17.

[0091] Outside the particle pickup zone 15, at the delivery zone 13 where particles are thrown off the mantle surface 21, the transport surface 9 is arranged to pass along a further compartment 28 within the support core 23 of the transport drum 22 where air pressure is the same as the ambient air pressure. To facilitate casting off of the particles, the air pressure inside the drum may at the delivery zone be increased slightly compared to the outside. The separation apparatus 9 comprises an air pump (not shown) with an air inlet that is arranged to suck air away from the inside of the drum, i.e. from the reduced pressure camber or ‘vacuum’ chamber 16, so that air pressure in that part of the inside of the drum is lower than ambient. An air outlet of the pump is arranged to assist in fluidizing the particles in the air gap 17 between the mantle surface 21 and the guide 18.

[0092] The separator 7 comprises a catch surface 12 on which identified particles 3 are caught to effect separation. The separator 7 is in this example embodied as a catch drum 29 that rotates in the direction of arrow P2. The catch drum 29 has a rotating catch surface. The axis of rotation of the catch drum is perpendicular to the conveying direction, i.e. parallel to the axis of the transport drum 22. The mantle 30 of the catch drum 29 is covered with hydrophilic material, which forms a recirculating catch surface 12. Particles that have become airborne at the delivery zone and that have travelled along the flight trajectory impact on the catch surface 12 of the separator 7. The identified particles 3 of which the affinity has been modified by droplets of water, adhere to the catch surface 12. The separator 7 includes a scraper 31, e.g. embodied as a blade to remove the caught particles 3 from the catch surface 12. For the particles 6 that have not been identified, the affinity with the separator 7 has not been modified, and has remained low. These particles 6 deflect off the catch surface 12 of the separator 7, and fall down while being guided along a guide plate 32 that keeps them separate from the particles 3 that are scraped off the catch drum 29.

[0093] In this embodiment, the affinity modifier 5 thus modifies the affinity of the identified particles 3 by applying affinity modifying particles 11 to the identified particles 3, in particular to increase the affinity between the identified particles 3 and the catch surface 12. The affinity modifying particles 11 are here applied directly to the identified particles 3, i.e. the identified particles 3 on the mantle surface 21 of the transport drum 22 are wetted. The mantle surface 30 of the catch drum 29 is dry and comprises hydrophilic material so that the wetted identified particles 3 get caught due to the formation of moisture bridges, and the particles 6 that are not identified remain dry and deflect from the mantle surface 30.

[0094] In the embodiment shown in FIG. 2, the affinity modifier cooperates with the catch surface of the separator. In this embodiment, the affinity modifier 5 modifies the affinity of the catch surface 12 by applying affinity modifying particles 11 to the catch surface 12 of the separator 7, in particular corresponding to that identified particles' position on the transport surface. In this embodiment, the mantle surface 30 of the catch drum 30 is wetted at a location that corresponds to a position of an identified particle 3 in the layer on the mantle surface 21 of the transport drum 22, corrected for its travel along the transport trajectory 20 and its expected movement along the flight path 14. The wetted location may e.g. be seen as a projected footprint of the particle on the catch surface. Upon impact with the catch surface 12 after the flight path 1, the identified particle 3 sticks to the wetted area of the mantle surface 30 due to the formation of moisture bridges. Particles that impact at dry areas of the mantle surface 12 stay dry and deflect from the catch surface. The speed of the catch surface is preferably made to correspond with the speed of the particle on the transport surface and in the flight path. For example, the circumferential speed of the catch drum is made to correspond to the circumferential speed of the transport chum, and an air jet may be provided to blow the particles along the flight path so that their flight speed is kept the same as the circumferential speeds of the drums. Elegantly, in an arrangement where the catch drum is positioned downstream and above the transport drum, the transport drum and the catch drum may be provided with the same diameter, and may be driven by the same motor via a transmission drives both drums in the same ratio, but with their sense of rotation inverted. The drums may rotate e.g. at one rotation per second.

[0095] By localized wetting of the catch surface of the catch drum it may be achieved that identified particles that are not wetted easily, e.g. thin metal wire segments from shredded electronics waste, may be caused to adhere to the catch surface drum. To prevent such particles from passing through the transport surface, the transport surface may e.g. be embodied as a closed surface. Further, it may be achieved that the identified particles can be separated while transferring relatively little liquid to the identified particles, which conserves energy when drying the stream of identified particles that are recovered via the separator. The catch surface of the catch drum may be dried off or otherwise regenerated to receive new affinity modifying particles after the identified particles have been removed from the surface.

[0096] Elegantly, the catch drum in this embodiment has a mantle surface that is made of abrasion resistant material, e.g. polyurethane.

[0097] The catch surface is preferably embodied as a rigid plane, similar to the transport surface.

[0098] Further, the catch surface and the transport surface may be provided with a surface with a low coefficient of restitution, e.g. 0.2 or less. A low coefficient of restitution prevents that the identified particles bounce off the catch surface. The coefficient of restitution is defined herein as the inverse of the ratio of the momentum of a particle on its way to impact the catch surface to that of the particle bouncing off the catch surface. In particular, the catch surface may be embodied as a visco-elastic surface. This can reduce the chance that identified particles bounce off the catch surface in spite of the affinity between the particle and the catch surface having been increased by application of affinity modifying particles on the particle and/or the catch surface, and may in particular provide that that the particles drop dead on the catch surface of the separator.

[0099] Thus is disclosed a method for separation of particles from a group of particles 4, comprising the steps of: providing a group of particles 4 that comprises particles with different properties, e.g. material, color, shape and/or size; supplying the group of particles 4 to a transport surface 9 that moves along a transport trajectory 20 as a rigid plane so as to bring the group of particles in a layer with a constant spatial relation on the transport surface 9; identifying particles 3 in the group of particles 4 that have a specific property; modifying an affinity between the identified particles 3 and a separator 7 relative to that affinity between non-identified particles 6 and the separator 7 using an affinity modifier 5, and separating the particles in the group based on their difference in the affinity with the separator 7. The particles of the group 4 are cast off the transport surface 9 to become airborne and travel along a flight path 14 to a catch surface 12 of the separator 7. The affinity of the identified particles is modified to increase the affinity between the identified particles 3 and the catch surface 12. In the first embodiment this is done by applying affinity modifying particles 11 directly to the identified particles 3. In the second embodiment this is done indirectly by applying affinity modifying particles 11 to the catch surface 12 at the position where the identified particle 3 impacts the catch surface 12.

[0100] As for the extent of this disclosure, it is pointed out that technical features which have been described may be susceptible of functional generalization. It is further pointed out that—insofar as not explicitly mentioned—such technical features can be considered separately from the context of the given exemplary embodiment, and can further be considered separately from the technical features with which they cooperate in the context of the example.

[0101] Further details of particles separation and in particular the use of magnetic and magnetizable powder are disclosed in document WO2016089209, the contents of which document are incorporated herein by reference.

[0102] It is pointed out that the invention is not limited to the exemplary embodiments represented here, and that many variations are possible. For example, the identifier may also be an identifier station comprising multiple identifiers arranged in a row or the separation apparatus may comprise multiple identifiers stations, preferably also arranged in a row. There may also be an affinity modifier station or a separator station.

[0103] Further, it is noted that the separator and the affinity modifier may be accommodated in a single device wherein modifying the affinity of identified particles and separation may be single action and may take place at the same time at a same position.

[0104] It is further noted that multiple separation apparatus may be placed in one go, e.g. above a conveyor, such that multiple different particles may be separated from a single stream of particles.

[0105] In addition, the transport surface and/or catch surface may be closed, e.g. in case it is used for particles that would pass through apertures, and/or e.g. in case of wetting of the transport and/or catch surface.

[0106] Also, it is noted that the separator may be embodied as a mechanical pick up device of which a contact surface contacts the group of particles for picking up the identified particles. Further, in case ferrosilicon particles are used to modify the affinity of the particles by forming hydrogen bridges with wetted, identified particles, it is also possible that the separator is embodied a magnet or that its contact surface is a magnet, has magnetic properties, or at least is coated with a magnetizable layer. In addition, if the separator is a magnet or its catch surface is a magnet, or at least is coated with a magnetizable layer, the separator may be used to recover magnetic or magnetizable particles that may have been discharged upstream.

[0107] These and other embodiments will be apparent to the person skilled in the art and are considered to lie within the scope of the invention as formulated by the following claims.

[0108] Aspects of the invention relate to a layering apparatus and a method for bringing a group of particles in a layer.

[0109] In many technical areas it can be beneficial to bring a group of particles, e.g. particles to be processed, in a layer. Such a layer may be for example a layer with a substantially single-particle thickness throughout the layer, for example substantially a monolayer-like layer of particles. A spatial particle density and/or a ratio between particle-filled space and other space, may be substantially constant throughout the layer. Thus, the particles may be distributed substantially evenly throughout the layer. In many applications, it is preferred that such a layer is substantially dense (i.e. substantially non-sparse) with particles, while overlap of particles along the layer is substantially limited. Such a layer of particles can enable that particles in the layer may be processed, e.g. analyzed and/or treated, efficiently and effectively.

[0110] A particular application which can benefit from such a layer relates to separation of particles, in particular for recycling purposes. The particles may be flake-shaped, e.g. plastic or glass, particles, for example produced by cutting, shredding and/or crushing waste, e.g. post-consumer waste, packaging waste and/or electronic waste. One aim of such an application is typically to separate particles according to one or more particle material properties (e.g. chemical composition, material density, color) and/or one or more particle geometry properties (e.g. size, shape, position).

[0111] For example, in such an application, a particle identifier and/or a particle separator can benefit from receiving particles to be identified and/or separated in such a substantially dense, monolayer-like configuration. While such a particle identifier and/or particle separator can often cope with a more sparse layer, their efficiency tends to reduce with increasing layer sparseness. For example, sensors, e.g. cameras, and/or ejectors, e.g. jets, that are used to respectively recognize and/or eject individual particles can operate more efficiently on more dense layers, while they also tend to operate less efficiently and/or less effectively when particles overlap more or more often.

[0112] A known method of bringing particles in a layer-like formation uses a vibratory feeder with its producing edge positioned above the surface of a conveyor. The particles drop from the edge of the feeder onto the surface of the conveyor, usually at a horizontal velocity which is less (e.g. about an order of magnitude less) than a respective horizontal velocity of the conveyor. When the particles drop from the feeder, they typically tumble as they pick up speed from direct or indirect contact with the conveyor. It has been found that this method tends to result in particles being distributed substantially randomly along the conveyor surface, wherein particles often overlap along said surface (e.g. particles are often at least partially on top of or below another particle) and/or wherein spatial particle density along the conveyor surface is relatively low with particles being distributed sparsely along the conveyor surface. In such a method, particle sparseness and particle overlap can sometimes be traded against each other, e.g. by adjusting a conveyor velocity with respect to a particle feeding rate of the feeder. However, such a method lacks the desired possibility of a combined reduction of particle sparseness and particle overlap.

[0113] In WO2016089209 a separation apparatus is proposed that comprises i.a. a layerizer arranged to bring a group of particles in a layer, wherein the layerizer comprises a recirculating transport surface on which the particles of the layer are carried along a transport trajectory.

[0114] Although this known apparatus includes many advantages, it also has a number of disadvantages. In particular, the use of a recirculating transport surface on which the particles of the layer are carried along a transport trajectory may have one or more disadvantages depending on the specific application. For example, such a recirculating transport surface may be relatively costly, susceptible to wear, and/or may occupy a relatively large space.

[0115] An object of the present invention, which object is related to the above-mentioned aspects, is to provide an alternative apparatus and method for bringing a group of particles in a layer. In this respect a particular object is to provide such an alternative apparatus which is less costly, more durable and/or more compact.

[0116] To that end, one aspect of the above-mentioned aspects of the present invention provides a method for bringing a group of particles in a layer.

[0117] The method comprises for each one particle of the group of particles: accelerating the one particle along a particle transport path, thereby spacing the one particle apart from at least one other particle of the group of particles; receiving the one particle on a particle receiving surface which extends along the particle transport path, thereby contributing the one particle to a layer of particles of the group of particles which layer is thereby formed on the particle receiving surface; and decelerating the accelerated one particle on the particle receiving surface along the particle transport path, thereby reducing a distance along the particle receiving surface between the one particle and at least one neighboring particle of the formed layer of particles.

[0118] It has been found that a group of particles can thus advantageously be brought in a layer, in particular a layer with one or more desired or advantageous properties such as a low particle sparsity and/or a low amount of particle overlap, in particular in a more economic and/or more reliable way and/or with reduced use of space compared to one or more known methods.

[0119] In particular, by thus accelerating the particles, overlap between the particles (in particular along the particle transport direction) may be advantageously reduced. Receiving the particles on the particle receiving surface enables the formation of a particle layer on said surface by the accelerated particles, in particular a relatively sparse and substantially a monolayer-like layer. Sparsity of the layer can subsequently be reduced by thus decelerating the particles on the particle receiving surface, in particular with no or at least relatively limited increase of overlap of particles.

[0120] It will be appreciated that the particle receiving surface itself may or may not move along the particle transport path. For example, particles may slide over the particle receiving surface. Some or all of the formed layer may leave the particle receiving surface, e.g. at a downstream and of said surface, e.g. as a substantially continuous stream of particles in a layer. Optionally, the accelerated one particle may be additionally decelerated, e.g. by a flow of fluid, while not on the particle receiving surface, e.g. prior to being received and decelerated on the particle receiving surface.

[0121] The accelerated one particle is preferably decelerated by friction between the one particle and the particle receiving surface.

[0122] It has been found that good particle deceleration can be realized in this way, so that in particular layer sparsity can be reduced while increase of particle overlap can be substantially limited.

[0123] The one particle may be accelerated along the particle transport path by a force of gravity acting on said one particle.

[0124] In this way a stable particle acceleration can be realized with relatively simple means.

[0125] Alternatively or additionally, a flow of fluid, e.g. air, may be provided along the particle transport path, wherein the one particle is accelerated along the particle transport path by said flow of fluid.

[0126] Good results have been obtained in this way. For example, the particles may be at least partly suspended in the fluid due to a relatively high-speed fluid flow. The fluid flow may be turbulent near a particle, which may further promote that particles are separated from each other.

[0127] At least one, preferably each, particle of the group of particles may be accelerated and/or decelerated at a different time and/or at a different rate and/or from a spaced apart position compared to at least one, preferably each, other particle of the group of particles.

[0128] In this way, the particles may be distributed substantially sparsely with limited or no overlap between particles. For example, particles may be fed into the accelerator at at least somewhat different times and/or at at least somewhat spaced apart positions, which differences may subsequently be amplified by the acceleration. Advantageous differences in acceleration and/or deceleration rates may result from (possibly small) differences between particles such as size, shape and/or mass differences.

[0129] The one particle may be accelerated along the particle transport path to a respective increased particle velocity along the particle transport path, wherein said increased particle velocity exceeds a velocity of the particle receiving surface along the particle transport path.

[0130] Thus, the particle may be decelerated by friction with the particle receiving surface upon being received on said surface.

[0131] The accelerated one particle may be decelerated along the particle transport path to a reduced particle velocity along the particle transport path, wherein said reduced particle velocity is equal to or exceeds said velocity of the particle receiving surface, wherein said reduced particle velocity is less than said increased particle velocity.

[0132] In this way, particles can be substantially prevented from reversing direction along the particle transport path, which could otherwise result in disadvantageous overlap between particles.

[0133] Each particle may be accelerated such that overlap of particles along the particle transport path is reduced, wherein each accelerated particle is decelerated such that sparsity of the formed layer of particles is reduced.

[0134] It will be appreciated that appropriate acceleration and deceleration profiles are dependent on i.a. specifics of the particles. Relevant examples are provided later on in the description.

[0135] Preferably (but not necessarily) each accelerated particle is decelerated such that the formed layer is a layer with a substantially constant spatial relation of the particles relative to each other in the layer.

[0136] For example, the particles may be brought in contact with each other by the deceleration such that their relative spatial positions in the layer become substantially constant. Alternatively or additionally, if desired, the formed layer may be processed further after the deceleration wherein the further processing modifies the layer such that the modified layer is a layer with a substantially constant spatial relation of the particles relative to each other in the layer.

[0137] The method may further comprise passing the layer of particles from the particle receiving surface to a downstream conveyor and conveying the layer on the downstream conveyor further along the particle transport path at a predetermined conveyor velocity which is defined relative to a rate at which the layer is passed to the downstream conveyor, thereby adjusting at least one of a particle overlap and a particle sparsity of the layer.

[0138] For example, it is thus possible to set the conveyor velocity slightly higher than the rate at which the layer is passed to the downstream conveyor, so as to create a slightly less dense (more sparse) layer of particles on the conveyor with a further reduced overlap of particles. Conversely, it is similarly possible to decrease sparseness and/or slightly increase overlap. Thus, a trade-off between sparseness and overlap can be made in this way, depending on application preferences, so that such a trade-off need not or not entirely be incorporated in the design of other parts of the method (although that it will be appreciated that such incorporation is also possible).

[0139] The method may further comprise subjecting, in particular upon the receiving, the received one particle to a reception force, for example a centrifugal force, which has a substantially non-zero component perpendicular to and towards the particle receiving surface.

[0140] Said reception force is preferably larger than a force of gravity acting on said one particle, more preferably at least double said force of gravity, more preferably at least five times said force of gravity, more preferably at least ten times said force of gravity, for example about twenty times said force of gravity.

[0141] It has been found that such a reception force can substantially inhibit received particles, often to a surprisingly large degree, from sliding over each other along the particle receiving surface and thus from overlapping on the particle receiving surface.

[0142] Another aspect provides a layering apparatus for bringing a group of particles in a layer. The layering apparatus comprises: a particle accelerator for accelerating particles of the group of particles along a particle transport path; and a particle receiving surface extending along the particle transport path for receiving particles of the group of particles and for decelerating received accelerated particles along the particle transport path, preferably downstream of the particle accelerator. The layering apparatus is configured to form a layer of particles of the group of particles on the particle receiving surface.

[0143] The above described method for bringing a group of particles in a layer can be performed using such a layering apparatus. In this way, the layering apparatus provides the above-mentioned advantages.

[0144] The particle receiving surface may be configured to decelerate received accelerated particles by friction between the particle receiving surface and the received particles.

[0145] At least one of a surface roughness, a material property, a shape and an orientation of the particle receiving surface may be configured to promote friction between the particle receiving surface and the received particles.

[0146] It will be appreciated that such friction can thus be promoted to an appropriate degree in various ways. Relevant examples are provided later on in the description.

[0147] The particle accelerator may be configured to accelerate particles of the group of particles by allowing said particles to be accelerated by a force of gravity acting on said particles, wherein, at the particle accelerator, the particle transport path extends in an at least partially downward direction.

[0148] Alternatively or additionally, the particle accelerator may be configured to provide a flow of fluid, e.g. air, along the particle transport path such that particles of the group of particles are accelerated by said flow of fluid.

[0149] The layering apparatus may further comprise a downstream conveyor configured to receive the layer of particles, in particular from the particle receiving surface, and for conveying the layer of particles further along the particle transport path at a predetermined conveyor velocity which is defined relative to a rate at which the layer is passed to the downstream conveyor such that at least one of a particle overlap and a particle sparsity of the layer is adjustable by the downstream conveyor.

[0150] One advantage of such a downstream conveyor which may be separate from the particle receiving surface is that the particle receiving surface can be substantially static, thus simplifying design and operation. In particular, the particle receiving surface can thus more easily be made to have an appropriate orientation, smoothness, curvature and/or material for its function in receiving and decelerating particles and forming a layer of particles.

[0151] The particle receiving surface may include a curved section along a respective curved section of the particle transport path 50. In this way, the layering apparatus, in particular the particle accelerator and the curved section, can be configured to subject particles received on the particle receiving surface to a centrifugal force which has a substantially non-zero component perpendicular to and towards the particle receiving surface.

[0152] Said centrifugal force is preferably larger than a force of gravity acting on a respective particle, more preferably at least double said force of gravity, more preferably at least five times said force of gravity, more preferably at least ten times said force of gravity, for example about twenty times said force of gravity.

[0153] Such a curved section can provide effective and robust means of subjecting particles to said centrifugal force, in particular in collaboration with the particle accelerator. Such a centrifugal force can substantially inhibit received particles, often to a surprisingly large degree, from sliding over each other along the particle receiving surface and thus from overlapping on the particle receiving surface

[0154] A further aspect of the invention provides a separation apparatus, comprising a layering apparatus as described above for bringing a group of particles in a layer. The separation apparatus further comprises: an identifier arranged to identify particles in the group of particles that have a specific property; a separator arranged to separate the particles in the group based on a difference in affinity between the particles and the separator; and an affinity modifier arranged to modify said affinity for identified particles relative to non-identified particles in the group.

[0155] A further aspect of the invention provides a method for separation of particles from a group of particles, wherein the method comprises: providing a group of particles that comprises particles with different properties, e.g. material, color, shape and/or size; and bringing the group of particles in a layer as described above.

[0156] The method for separation of particles further comprises: identifying particles in the group of particles that have a specific property; modifying an affinity between the identified particles and a separator relative to that affinity between non-identified particles and the separator using an affinity modifier; and separating the particles in the group based on their difference in the affinity with the separator.

[0157] Thus, an alternative apparatus and alternative method for separation of particles is provided, which can in particular be less costly, more durable and/or more compact compared to a known apparatus and/or a known method.

[0158] The above-mentioned aspects will be further elucidated on the basis of exemplary embodiments which are represented in drawings. In the drawings:

[0159] FIG. 3 shows a schematic view of a first embodiment of the layering apparatus; and

[0160] FIG. 4 shows a schematic view of a second embodiment of the layering apparatus.

[0161] It is noted that the drawings are merely schematic representations of preferred, but non-limiting, embodiments of the invention. In the drawings, similar or corresponding elements have been provided with similar or corresponding reference signs.

[0162] FIGS. 3 and 4 show a respective first and second embodiment of a layering apparatus 52 for bringing a group of particles 4 in a layer. It will be appreciated that features of these embodiments are not mutually exclusive and that such features may be advantageously combined.

[0163] The layering apparatus 52 comprises a particle accelerator 53 for accelerating particles of the group of particles 4 along a particle transport path 50.

[0164] The layering apparatus 52 further comprises a particle receiving surface 51 extending along the particle transport path 50 for receiving particles of the group of particles 4 and for decelerating received accelerated particles along the particle transport path 50, preferably downstream of the particle accelerator 53.

[0165] As shown, the layering apparatus 52 is configured to form a layer of particles of the group of particles 4 on the particle receiving surface 51.

[0166] As shown in FIG. 3, particles from the group of particles 4 may be fed into the particle accelerator by a feeder, e.g. a feed plate 27, which may be for example a vibratory feeder.

[0167] In the shown embodiments, the particle receiving surface 51 is configured to decelerate received accelerated particles by friction between the particle receiving surface 51 and the received particles. A slope of the particle receiving surface 51 as shown in FIGS. 3 and 4 decreases along the particle transport path 50 so that particles are decelerated by friction which substantially increases with the decreasing slope.

[0168] Alternatively or additionally, for example, surface roughness, a material property, a shape and/or an orientation of the particle receiving surface 51 can be configured to promote friction between the particle receiving surface 51. Such friction typically partly depends on properties of the particles. Thus, as will be appreciated, one or more properties of the particle receiving surface 51 may be selected depending on such particle properties. For example, in the case of relatively smooth particles, a relatively rough particle receiving surface 51 may be selected.

[0169] The particle receiving surface 51 may include a curved section 51 along a respective curved section of the particle transport path 50. In this way, the layering apparatus may be configured to subject particles received on the particle receiving surface 51 to a centrifugal force which has a substantially non-zero component perpendicular to and towards the particle receiving surface 51.

[0170] In the embodiment of FIG. 3, the particle accelerator 53 is configured to accelerate particles of the group of particles 4 by allowing said particles to be accelerated by a force of gravity acting on said particles, wherein, at the particle accelerator 53, the particle transport path 50 extends in an at least partially downward direction. For example, the particle accelerator 53 may thus comprise a slide or a chute.

[0171] In the embodiment of FIG. 4, the particle accelerator 53 is configured to provide a flow of fluid, e.g. air, along the particle transport path such that particles of the group of particles 4 are accelerated by said flow of fluid. For example, the particle accelerator 53 may thus comprise a fluid flow channel and a fluid pump, e.g. an air pump.

[0172] FIG. 4 further shows a downstream conveyor 54 configured to receive the layer of particles, in particular from the particle receiving surface 51, and for conveying the layer of particles further along the particle transport path 50 at a predetermined conveyor velocity. The predetermined conveyor velocity is defined relative to a rate at which the layer is passed to the downstream conveyor. In this way at least one of a particle overlap and a particle sparsity of the layer is adjustable by the downstream conveyor 54.

[0173] With additional reference to FIGS. 1 and 2, it will be appreciated that the layering apparatus 52 may advantageously be used as an alternative to a part of the separation apparatus 1, in particular a part upstream of the flight path 14. The layering apparatus 52 may also advantageously be used by addition to the separation apparatus 1 as shown in FIGS. 1 and 2, for example upstream of the transport drum 22, wherein the layering apparatus 52 can for example advantageously reduce a particle layer thickness upstream of the transport drum 22.

[0174] While the invention has been explained using exemplary embodiments and drawings, it will be appreciated that these are not intended as limiting the scope of the invention, which scope is provided by the claims. For example, the invention may be applied in other areas than recycling. The layering apparatus may or may not comprise a downstream conveyor and may or may not comprise a feed plate. The layer may be passed and/or processed downstream of the layering apparatus in various ways. For example, the layer may be fed onto a conveyor such as a conveyor belt and/or a conveyor drum and/or onto a slide plate and/or the layer may be dropped from an edge to form a layer-like curtain of particles. Particles may be accelerated by gravity, by a fluid flow, and/or by other means. A layer of particles formed by the method may or may not be a monolayer of particles and the layer may or may not be substantially sparse. A reception force may be a centrifugal force and/or another type of force, e.g. a suction force effected by suction of a fluid, e.g. air, through a fluid-transmissive (e.g. porous) part of the particle receiving surface. Particles may be of various shapes and sizes and/or varying in terms of other properties. For example, one, some or all of the particles may be flake-like particles. In a formed layer, particles may or may not be in contact with each other and may or may not overlap each other. Particles in the layer formed in the layering apparatus and/or by the method for bringing particles into a layer may or may not have a constant spatial relation relative to each other in the layer. These and other variations, alternatives and combinations are possible, as will be appreciated by the skilled person.

[0175] In the following, a first and a second example will be provided of a method according to the invention for bringing a group of particles in a layer. It will be appreciated that these examples are provided only for elucidation of the invention and that they are in no way to be construed as limiting the scope of the invention, which scope is provided by the claims.

FIRST EXAMPLE

[0176] Suppose that an objective is, in this first example, to create a dense monolayer-like layer of flake-like particles (flakes) with about 40% particle coverage of a conveyor surface area at about 2 m/s transport velocity of the conveyor. The flakes have a thickness of about 0.5 mm and a diameter in the range of about 2 to about 12 mm and they have mostly irregular shapes, for example pentagonal shapes. Then the flakes could be accelerated first to about 8 m/s and deposited as a sliding flow at this velocity on the particle receiving surface. Because the slicing flow initially has an about four times higher velocity than the conveyor, the flakes will initially form a layer that has a particle coverage of only about 10% of the surface. At this low coverage, few flakes will overlap. Surprisingly, the actual flake overlap rate seen in experiments is often even less than predicted from random deposition experiments. It is often observed that the flakes are arranged in a substantially tile-like pattern without any visible overlap. A possible explanation for this is that the high flake speed of the flakes creates sufficient contact and drag forces to make the position of one flake on top of another into an unstable state. The sliding flow decelerates on the particle receiving surface and the flakes hit each other in the ever denser flow, while the flakes do not tend to slide over one another and so a dense monolayer-like layer is formed.

SECOND EXAMPLE

[0177] In this second example, a flow of about 2 ton/h of (mainly) HDPE flakes (particles) was accelerated by a flow of air in a standard pneumatic transport pipe to about 25 m/s and then decelerated back to about 10-12 m/s by increasing the cross-sectional area of the air flow. Then the flakes were injected into a semi-circular stainless steel sheet (as shown schematically in FIG. 4, including particle receiving surface 51) with a diameter of about 0.6 m and a friction coefficient between flakes and steel of about 0.5. At the lower, downstream end of the sheet, the flake flow speed had been reduced to about 2-2.5 m/s and the coverage had been increased to over 40%, virtually free of overlap. At this speed, the flakes were transferred to a conveyor running at about 2.5 m/s.

LIST OF REFERENCE SIGNS

[0178] 1. Separation apparatus [0179] 2. Identifier [0180] 3. Identified particle [0181] 4. Group of particles [0182] 5. Affinity modifier [0183] 6. Non-identified particles [0184] 7. Separator [0185] 8. Layerizer [0186] 9. Rigid planar transport surface [0187] 10. Optical sensor [0188] 11. Affinity modifying particles [0189] 12. Catch surface [0190] 13. Particle delivery zone [0191] 14. Flight path [0192] 15. particle pickup zone [0193] 16. Zone with reduced air pressure/vacuum chamber [0194] 17. Air gap [0195] 18. Guide [0196] 19. Apertures [0197] 20. Transport trajectory [0198] 21. Mantle surface [0199] 22. Transport drum [0200] 23. Core [0201] 24. Apertures [0202] 25. Feed device [0203] 26. Fluidized bed of particles [0204] 27 Feed plate. [0205] 28. Further chamber [0206] 29. Catch drum [0207] 30. Mantle [0208] 31. Scraper [0209] 32. Guide plate [0210] P1 Rotation direction transport drum [0211] P2. Rotation direction catch drum [0212] P3. Air flow [0213] 50. Transport path [0214] 51. Particle receiving surface [0215] 52. Layering apparatus [0216] 53. Particle accelerator [0217] 54. Downstream conveyor