The invention relates to a method for picking up particles from a mixture constituted of particles, the method making use of a drum for picking up particles, a belt conveyor to transport the mixture and to press the mixture against the drum, and pressure rollers for the belt conveyor. The invention likewise relates to a device for applying this method.

A similar device for picking up certain particles from a mixture is known from WO 93/17852. Here, a drum with a surface having a certain surface structure is applied to pick up certain particles, such as softened parts of thermoplastic synthetic material from a mixture constituted of particles. Subsequently the particles picked up are separated from the drum, for instance, by a separating element and conveyed to a storage depot. During the picking up of the preferably softened parts of thermoplastic synthetic material by means of the drum, the mixture, by means of a belt conveyor, is jammed between the drum and the belt conveyor, so that, during this jamming, the parts of synthetic material to be picked up are co-operating with the surface of the drum, more particularly, are pressed against the surface of the drum in order to be picked up by the drum. The force pressing these particles against the surface of the drum being determined by the mutual position of the drum, the belt conveyor and the pressure rollers.

The purpose of the present invention is to improve the picking up of particles from a mixture constituted of particles.

In order to attain this purpose the method comprises the pressing of at least one pressure roller against the belt conveyor by an adjustable force, so that the mixture jammed between the belt conveyor and the drum is pressed against the surface of the drum by an adjustable force.

The method according to the invention, whereby the force of pressure being adjustable has the advantage that this force may be adapted or modified in a simple manner in order to pick up at will certain kinds of particles, preferably softened parts of thermoplastic synthetic material from a mixture. This is possible since the device according to the invention enables to adjust the force pressing the mixture against the drum, namely with respect to the properties of the particles one wishes to pick up and with respect to the properties of the mixture conveyed to the drum. The force pressing the mixture against the surface of the drum may be adjusted such, for instance, that at a certain temperature of a certain mixture a certain kind of softened parts of thermoplastic synthetic material may be picked up efficiently from the mixture by the drum.

According to a preferred embodiment a plurality of pressure rollers are provided which may be pressed against the drum by an adjustable force, where the force of the respective pressure rollers may be adjusted differently and, preferably, the force of the respective pressure rollers can be adjusted according to a certain course according to the direction in which the mixture is conveyed. This will enable to improve the picking up of certain particles from a mixture.

To that effect, the invention also comprises a device to pick up particles from a mixture, comprising a drum for picking up particles, comprising a belt conveyor for conveying the mixture and to press the mixture against the drum and which comprises pressure rollers for the belt conveyor, wherein the device comprising means to press at least one pressure roller against the belt conveyor by an adjustable force, so that the mixture jammed between the belt conveyor and the drum is pressed against the surface of the drum by an adjustable force.

According to a preferred embodiment the device comprises a plurality of pressure rollers, the outer pressure rollers being mounted fixedly and at least one pressure roller, installed between the outer pressure rollers, being supported by means to press this at least one pressure roller against the belt conveyor by an adjustable force.

Preferably, all pressure rollers installed between the outer pressure rollers are supported by means to press these pressure rollers against the belt conveyor by an adjustable force. Installing the outer pressure rollers fixedly enables the position of the belt conveyor to be adjusted with respect to the drum in a simple manner and irrespective of the tension in the belt conveyor, while the pressure rollers, supported by the means according to the invention determine the force by which the belt conveyor is forced towards the drum and the mixture is pressed against the surface of the drum. Each of the various pressure rollers, pressed by the aforementioned means may be pressed against the drum by a respective force. According to a variant embodiment, the device comprises a plurality of pressure rollers, which are supported by means to press these pressure rollers against the belt conveyor by an adjustable force.

According to an embodiment the means to press at least one pressure roller against the belt conveyor by an adjustable force, comprise at least one pneumatic cylinder and a pressure regulator, the pressure regulator being provided between the at least one pneumatic cylinder and a compressed air source and is used to adjust the pressure of the compressed air in the at least one pneumatic cylinder. This pressure regulator may consist of an electrically controlled pressure regulator. This allows the force to be adjusted or adjustably adjusted by means of a pressure regulator in a simple manner, by which the mixture is pressed against the drum by at least one pressure roller. In doing so, it is likewise possible, in a simple manner, to remotely control this force, which enables, for instance, the aforementioned force to be adjustably controlled while the device is operating. This has not only the advantage that the device is allowed to continue to operate while the force is adjusted, but has first of all the advantage that the result of the adjustment becomes immediately visible. This is especially advantageous to easily obtain a suitable adjustment of the aforementioned force by a regulation, if the mixture conveyed to the drum is modified and/or the particles to be removed are modified. A similar regulation can be based on the relative amount and/or on the nature of the mixture picked up and/or on the relative amount and/or on the nature of the mixture not picked up. A pneumatic cylinder has also the advantage that the force exerted by the cylinder hardly depends on the relative positions of the cylinder and the pressure roller.

According an embodiment, the pressure rollers comprise an exterior jacket containing a heat-resistant compressible silicone foam.

The properties and further advantages of the invention will be explained hereafter with the help of non-limiting exemplified embodiments represented in the drawings in the following detailed description. In this description reference is made to the following drawings, in which: figure 1 represents a device according to the invention; figure 2 represents a part of the device on an enlarged scale; figure 3 represents a side view of the part shown in figure 2; figure 4 represents a variant of figure 2; figure 5 represents a variant of figure 4; figure 6 represents a variant of figure 1; figure 7 represents a variant of figure 6; The device according to the invention represented in figure 1 comprises a drum 1 for picking up particles from a mixture 2 consisting of particles. The surface of the drum 1 may show a grooved surface structure or any other kind of extension surface allowing to pick up particles from the mixture. Similar surface structures are described, for example, in 93/17852. On both sides, the drum 1 comprises a shaft 3 each time rotatably supported by bearings in a supporting element 4, adjustable as to height, attached to the frame 5 of the device. The drum 1 may be driven by a drive motor 6 by means of transmission means not represented. The device comprises adjusting means 7 in order to adjust the supporting element 4 for the drum 1 in a certain position as to height with respect to the frame 5, comprising, for instance, adjusting screws 7A in order to adjust their relative positions as to height and comprising a bolt and slot connection 7B in order to fix the position adjusted as to height. Further, the device comprises a belt conveyor 8 to convey the mixture 2 to the drum 1 and a plurality of pressure rollers 9,10, 11,12 to bring the belt conveyor 8 to the drum 1. Preferably, the pressure rollers 9,10, 11 and 12 each consist of an elongated cylinder extending over the entire width of the belt conveyor 8. The drum 1 also extends over the full width of the belt conveyor 8. The belt conveyor 8 is further conducted through a deflecting element 13 and deflecting rollers 14,15, 16 and 17. By means of transmission means not represented, the deflecting roller 15, can be driven by a drive motor 18, to drive the belt conveyor 8 according to the direction A in which the mixture is conveyed. The pressure rollers 9 to 12 are used to press the belt conveyor 8 against the drum 1, so that the mixture 2 will be jammed between the drum 1 and the belt conveyer 8 and thereby will be pressed against the drum 1.

The device further comprises a separating element 19 to separate the mixture 20 picked up by the drum 1 from the drum 1 and take it to the belt conveyor 21, which will remove this mixture 20 having been picked up. In the embodiment represented in figure 1, this separating element 19 consists, for instance, of a comb or brush rotatably driven, engaging the grooves of the surface of the drum 1.

Further, a rotatably driven brush 22 may be provided to clean the belt conveyor 8. In figure 1 are further provided another belt conveyor 23 for supplying the mixture 2, a heating element 24 for heating the mixture 2, and a belt conveyor 25 to remove the mixture 26 not picked up by the drum 1.

According to the invention the device 1 further comprises means 27 to press at least one pressure roller against the belt conveyor 8 by an adjustable force, and thus forcing towards the drum 1 at least one pressure roller and the belt conveyor 8.

In the embodiment of the figures 1 to 3, both ends of the outer pressure rollers 9 and 12 each are supported in bearings rotatable around a shaft 28,29 fixed in a certain position respectively along a slot 30,31, that is preferably installed horizontally, to a frame of the device according to the invention, not represented, so that these outer pressure rollers 9 and 12 are installed fixedly. Both ends of the pressure rollers 10 and 11 installed between the outer pressure rollers 9 and 12 are supported each by means 27 according to the invention. The position as to height of the outer pressure rollers 9 and 12 determining the position as to height of the belt conveyor 8. The drum 1 being adjusted here by the adjusting means 7 in such a position as to height that the drum 1 is situated at a certain distance from the pressure rollers 9 and 12 which, for instance, is slightly greater than the thickness of the belt conveyor 8.

As clarified in the figures 2 and 3, the means 27 according to the invention comprise, for instance, two pneumatic cylinders 32 the housing of which is attached to the frame 33 of the device, and the connecting rods 34 of which support a shaft 35,36 on which the pressure rollers 10,11 are mounted on bearings. The pneumatic cylinders 32 belonging to a pressure roller 10 or 11 are each supplied with compressed air at a certain pressure, for instance, in the order of magnitude of 4 to 6 bar which is determined by a respective pressure regulator 37 provided between these cylinders 32 and a source of compressed air 38. A similar pressure regulator 37 for adjusting the pressure supplied, allows the force to be adjusted by which the cylinders 32 are pressing against a pressure roller 10 or 11, and also by which the pressure rollers 10 and 11 are pressing against the belt conveyor 8. It is possible here to adjust the pressure of the cylinders 32 for each pressure roller 10 or 11 separately and differently. According to a variant, the cylinders 32 belonging to the different pressure rollers 10, 11 can be supplied from one single pressure regulator, so that, in case the cylinders 32 are of an identical design, also the different pressure rollers 10,11 may be controlled by an identical force. Preferably, the pressure regulator 37 is installed in a place well accessible to the operator, which, for instance, is away from the drum 1, so that the operator will be able to easily adjust or regulate the pressure, for instance, whilst he can keep an eye on the mixtures 2,20 and 26. In case the pressure regulator may be controlled electrically, regulating the pressure and thereby the force may, for example, be done from a control room installed at a relatively long distance away from the device according to the invention. Moreover, it is possible to provide at least one camera near the device according to the invention and at least one accompanying monitor near the operator, for example, to keep an eye on the operation of the device according to the invention and to be able to watch from a distance the consequences of an adjustment of the aforementioned force.

If the belt conveyor 8 and the drum 1 have a width in the order of magnitude of one meter, it may be desirable to support the pressure rollers 10,11 once again between both their ends in order to prevent a deflexion of the pressure rollers 10,11. In this case, for example, at least one supporting shell 39 is provided, co-operating with a pressure roller 10,11 and being mounted on a connecting rod 40 of a cylinder 41, which is connected to the pressure regulator 37 in a manner analogous to the cylinders 32. The surface of the supporting shell 39, co-operating with the pressure roller 10,11 may comprise, for instance, a plurality of small supporting rollers or balls, not represented, in order to limit the friction between the supporting shell 39 and the pressure rollers 10,11.

The pressure rollers 9 to 12 preferably comprise an outer jacket 42 comprising a compressible, heat-resistant silicone foam. Preferably, silicone foam is applied to that effect, having a hardness situated between 5 and 45 according to Shore's scale. The outer jacket 42 is mounted on bearings by means of a bearing 43 on a shaft 28,29, 35,36 respectively. The outer jacket 42 may contain reinforcing fibres, such as carbon fibres, in order to avoid wear or the formation of cracks of this outer jacket 42. According to a variant, not only the outer jacket, but also primarily the entire pressure roller is made of compressible, heat- resistant silicone foam.

According to a variant embodiment, not represented, only the pressure roller 10 or the pressure roller 11 is supported by means 27 according to the invention. According to a variant embodiment, not represented, the means 27 may also consist of, for instance, one single supporting shell which, near the centre of a pressure roller 10,11, co-operates with this pressure roller 10,11 in order to force the belt conveyor 8 towards the drum 1.

While the device according to the invention is operating, a mixture 2 with particles is supplied by the belt conveyor 23 and subsequently conducted to the drum 1 by the belt conveyor 8. In addition, this mixture 2 is heated by a heating element 24, so that, for example, the particles primarily consisting of thermoplastic parts of synthetic material are softened. Subsequently, this mixture is jammed between the belt conveyor 8 and the drum 1, so that certain particles of the mixture 2 are pressed into the surface of the drum 1 and constitute the mixture 20 which is picked up.

Moreover, the drum 1 is driven according to the direction of rotation B for the mixture 2 conveyed, and this, preferably, at a rate which is equal to the rate of the belt conveyor 8, which furthers the picking up of the particles. According to a variant, the drum 1 may also be driven by the particles 2 displaced by the belt conveyor 8. Subsequently, the mixture 20 picked up is removed from the drum 1 by a separating element 19 and conducted to a belt conveyor 21, by means of which this mixture 20 is further removed. The mixture 26 not picked up by the drum is further conducted, by the belt conveyor 8, to the belt conveyor 25, which further removes this mixture 26.

In figure 4 a variant embodiment is represented where apart from the pressure rollers 9 to 12, also the pressure rollers 44 and 45 are represented which are both supported by aforementioned means 27. In this embodiment the pressure rollers 9 to 12 are installed and carried out in a manner analogous to that of the embodiment of figures 1 to 3. The pressure rollers 44 and 45 here being forced towards the drum 1 by the means 27 in an almost radial direction. Unlike the embodiment of the figures 1 to 3, in this embodiment the shaft 3 of the drum 1 is not supported by bearings, but the drum 1 rests on or is supported by the pressure rollers. The position of the drum 1 as to height is here determined by the pressure rollers 9 and 12 installed fixedly, and the drum 1 is also supported by all the other pressure rollers 10,11, 44 and 45. Preferably, the force exerted by the pressure rollers 10,11, 44 and 45 and the weight of the drum 1 are chosen such that the drum 1 is prevented from being lifted upwards and will no longer be supported by the pressure rollers 9 and 12. According to the invention, it is here also possible to adapt the pressing force of the different pressure rollers 10,11, 44 and 45. According to a variant not represented, it is possible to force the drum 1 towards the pressure rollers, apart from by its own weight, also by pressure springs acting, for example, on the shaft 3, this in case the own weight of the drum 1, for example, is too low to provoke the jamming required of the mixture 2 between the belt conveyor 8 and the drum 1. According to a variant, it is possible to install the means 27 for the pressure rollers 10 and 11 in such a manner that they move the pressure rollers 10 or 11 towards the drum 1 in a radial direction.

By providing a plurality of pressure rollers 9 to 12 and 44 to 45 it is possible to provide a plurality of jamming points created near a pressure roller between the belt conveyor 8 and the drum 1 which favours the picking up of the mixture 20 by the drum 1. Since near such pressure points the mixture 2 is jammed between the belt conveyor 8 and the drum 1 by a relatively stronger force than in the places situated in between where the belt conveyor 8 is not supported. It may be an advantage here to adjust the force exerted on the belt conveyor 8 by the respective pressure rollers according to a course in the direction A in which the mixture 2 is conveyed. It is possible here that the adjustable force of the respective pressure rollers increases or decreases, progressing according to the direction A in which the mixture 2 is conveyed. An increasing force is advantageous if the particles to be picked up are cooling down whilst they are conveyed along the drum 1 and therefore become harder and more force is required to press them against the drum. It has been established by experience that the efficiency for picking up softened parts of thermoplastic synthetic material, originating, for instance, from automobile bumpers and the particles being of the size of between 8 and 30 mm, is favoured by a preferably slightly increasing force of the various pressure rollers according to the direction A in which the mixture is conveyed. To that effect, when using a belt conveyor 8 having a width of one meter and a drum having a diameter of 0.4 meter, the pressure supplied to the means 27 for the pressure roller 44, for example, amounts to 5 bar, that for the pressure roller 10, for example, to 5.3 bar, that for the pressure roller 10, for example, to 5.6 bar and that for the pressure roller 44, for example, to 6 bar, so that, for example, a pressing force of 100,106, 112 and 120 Newton respectively is generated by the pressure rollers 44,9, 10,45.

According to a variant embodiment, the pressure rollers 9 and 12 in the embodiments according to the figures 1 to 4 are likewise forced against the belt conveyor 8 by the means 27. As a consequence of this embodiment, the force with which the mixture 2 is jammed between the belt conveyor 8 and the drum 1 near the pressure rollers 9 and 12 is strongly influenced by the tension in the belt conveyor 8.

Notwithstanding that in the embodiments represented, the belt conveyor 8 is supported by four or six pressure rollers, it is of course also possible to support the belt conveyor by three, five or more than six pressure rollers.

In figure 5 a variant embodiment according to the invention is represented, in which all pressure rollers 9 to 12 and 44 to 45 are installed fixedly, for example, in a manner as described for the pressure rollers 9 and 12 of the figures 1 to 4 and in which the drum 1 is controlled by means 47 to press the pressure rollers 9 to 12 and 44 to 45 through the drum 1 against the belt conveyor 8 by an adjustable force, so that the mixture 2 jammed between the belt conveyor 8 and the drum 1 is pressed against the surface of the drum 1 by an adjustable force. The means 47 comprise, for example, two double acting cylinders 48 each driving an end of the shaft 3 of the drum 1 and which, for example, are connected together to a source of compressed air 38 through a valve system 49 such as a 3/2 valve and through a pressure regulator 37. The housing of each cylinder 48 is, for example, near a respective end of the shaft 3 of the drum 1 fixedly attached to the frame of the device. Each cylinder 48 further comprises a connecting rod 50 to which a respective end of the shaft 3 of the drum 1 is mounted on a bearing.

In order to increase the force by which the belt conveyor 8 is forced towards the drum 1 by the pressure rollers, the valve system 49 is brought into a first position, in which the compressed air is supplied to the top 51 of the double acting cylinder 48, so that the drum 1 is forced downwards.

In order to reduce the force by which the belt conveyor 8 is forced towards the drum 1 by the pressure rollers, the valve system 49 is brought into a second position, in which compressed air is supplied to the bottom 52 of the double acting cylinder 48, so that the drum 1 is forced upwards against its weight. The pressure of the compressed air and also the aforementioned force may be adjusted, as already mentioned, in an analogous manner by a pressure regulator 37. Since the drum 1 is usually rather heavy, the double acting cylinder 48 may be controlled hydraulically instead of pneumatically in an analogous manner. It will be clear that the means 47 also allow the drum 1 to be lifted over a relatively long distance, in order to be able to clean the drum 1 for example.

In this embodiment the drum 1 also comprises heating elements 53 in order to heat the drum 1 and thereby the mixture 2 additionally near the drum 1 and thereby preventing the mixture 2 conveyed along the drum 1 from cooling or even to obtain that this mixture 2 is even heated. These heating elements 53 consist, for example, of electric resistances, conducting channels for hot oil, conducting channels for hot water or steam or any other kind of heating elements.

The mixture 20 removed by the belt conveyor 21 may be brought to a storage place. Such as represented in figure 3, this mixture 20 may likewise be conducted to a device 54 for cutting or grinding this mixture 20. According to a variant not represented, this mixture 20 is brought to a device for this mixture 20 still hot to be extruded.

In the embodiment according to figure 6, two units 55 and 56 are installed one after the other for picking up particles from a mixture 2, each being designed in a manner practically analogous to the embodiment of figure 1. Each of the aforementioned units 55,56 also comprises a number of spray nozzles 57 near the brush 22 for cleaning and/or cooling the belt conveyor 8. Each unit 55,56 further also comprises a supporting element 58 for the belt conveyor 8, which is, for example, water-cooled or provided with cooling-fins. In these embodiments each unit 55,56 comprises means 47 with a connecting rod 50 driven by a cylinder, to control the drum 1, being carried out in a manner analogous to the embodiment of figure 5 and which may be used to additionally adjust the force by which the pressure rollers press the belt conveyor 8 against the drum 1. Thereby, the means 47 can, for example, generate a force, so that the pressure, exerted by the drum 1 on the pressure rollers will be reduced or the pressure exerted by the drum 1 on the pressure rollers will be increased. According to a variant, the adjusting means 7 designed in a manner analogous to figure 1, are adjusted such that the connecting rod 50 of the cylinder will be stopped by the lower wall of the cylinder during operation and thereby the force exerted by the means 47 will be limited and determined by the position of the drum 1 with respect to the pressure rollers.

The drum 1, according to the direction A in which the material is conveyed, installed first, picks up a mixture 20 from the mixture 2 and allows a mixture 59 to pass. This mixture 59 is conducted to a next drum 1, which picks up a mixture 60 from the mixture 59 and allows a mixture 26 to pass.

In the embodiment according to figure 7, two units 55, 56 are likewise installed one after the other to pick up particles from a mixture 2, only one single belt conveyor 8 being provided, conducted along two drums 1. In this embodiment, also a deflecting roller 59 is provided for the belt conveyor 8.

The embodiment of the figures 6 and 7 allow, for instance, for a different adjustment of the force by which the respective pressure rollers 9 to 12 are pressing against the corresponding belt conveyor 8, a selective picking up of certain particles by one of the units 55 or 56, which may, for example, comprise only certain parts of thermoplastic synthetic material, and this even in case the particles comprise different parts of thermoplastic synthetic material, being softened at nearly the same temperature.

This picking up of a mixture 20 or 60 by a certain unit 55 or 56 in a selective manner is possible, since the polymers of different softened parts of thermoplastic synthetic material will start to shear under a different pressure and will start to engage the drum 1. In order to allow such a separation, the force exerted by the pressure rollers 9 to 12 of the unit 55 is adjusted at a lower value than the force exerted by the pressure rollers 9 to 12 of the unit 56.

According to another possibility only one of the units 55 or 56 is provided with means 27,47 according to the invention and the other unit is designed according to the state of the art. Thereby, the first one installed according to the direction A in which the mixture is conveyed is preferably provided with means 27,47 according to the invention, since that unit 55 is then capable to pick up the particles selectively determined, which of course are no longer supplied to the second unit 56.

The efficiency when picking up certain kinds of particles from a mixture consisting of particles may be determined, for example, as the product of the percentage of a kind of particles desired picked up from the mixture and the percentage that such particles desired represent of the quantity picked up. If 90% of the particles desired is picked up from the mixture and 90% of the quantity picked up is made up of such particles desired, then an efficiency of 81% is obtained. In order to obtain an efficiency as good as possible, it is important to pick up as much particles desired as possible from the mixture and to be precise, without picking up any other material from the mixture. The method according to the invention allows the pressing force to be adjusted sufficiently to pick up the particles desired from the mixture and to adjust the pressing force at not too high a value, in order to avoid that particles not desired are picked up from the mixture. In order to obtain a good efficiency the force of the pressure rollers should be adjusted, depending on the size and the composition of the particles of the mixture and depending on the size and the composition of the particles desired to be picked up from the mixture.

Notwithstanding that the use of pneumatic cylinders is advantageous, according to variant embodiments, other means may also be applied to adjust the force by which at least one pressure roller is pressed against the belt conveyor.

According to a possibility, such other means comprise at least one electromagnet forcing at least one pressure roller towards the belt conveyor and a control unit to adjust the current supplied to the electromagnet. Since the force by which an electromagnet forces a pressure roller towards the belt conveyor, is at the same time a function of the position of the pressure roller, preferably the actual or measured position of the drive element of the electromagnet or the mutual position of the electromagnet and the pressure roller should be taken into account to control the electromagnet. Such a control is possible but is relatively complicated, because of which this variant embodiment is less suitable in case mixtures with particles having relatively large differences as to dimensions are applied.

According to yet another variant embodiment, such other means may also comprise springs, co-operating with adjusting means to adjust the stiffness or the force of those springs.

The adjusting means may, for instance, adjust the position of the fixed point of support of the spring or may, in case of spiral springs, block certain windings of the spiral spring. An embodiment with springs is most of the time also less suitable to be applied in case mixtures with particles with relatively large difference as to dimensions are applied, unless these differences may be neglected compared to the length of the spring. According to yet another variant, means may be provided to adjust the force by which a pressure roller 9,10, 11,12, 44 or 45 is pressed against the belt conveyor 8, comprising a controllable servo motor or a controllable stepping motor in order to mutually position the pressure roller and the drum 1. Thereby the force is determined by the mutual position of the pressure roller and the drum 1 and the force may be adjusted by changing the mutual position of the pressure roller and the drum 1. If the mixture 2 shows particles of a constant size, the force by which the mixture 2 is pressed against the surface of the drum 1 will be likewise nearly constant. If the particles of the mixture 2 are mutually different as to size, the force will be, unlike the embodiment, where the means 27 comprise pneumatic cylinders, change according to the size of the particles of the mixture 2. However, in the embodiment with servomotor or with stepping motor, the average force will be nearly constant and adjustable by means of the servomotor or the stepping motor. If the particles show only slight differences in size and, for example, elastically deformable or compressible pressure rollers 9,10, 11,12, 44 and 45 are applied, the adjustable force by which the pressure rollers are pressed against the belt conveyor 8 and also the force by which the mixture 2 is jammed between the belt conveyor 8 and the drum 1, and is therefore pressed against the surface of the drum 1 will be likewise nearly constant. Combinations of the aforementioned embodiments are, of course, also possible such as replacing at least one of the pneumatic means 27,47 by a servo motor, a stepping motor, an electromagnet, springs or other similar means. The device according to the invention is most suitable to pick up from a mixture particles of parts of thermoplastic synthetic material, brought to a certain temperature, and which, therefore, have been softened. The invention is of course not restricted to picking up similar particles. The device according to the invention allows for picking up any particles from a mixture by means of a drum 1, which under influence of a jamming at a certain force between the drum 1 and the belt conveyor 8 may be picked up by the drum 1.

The mixture consisting of particles, preferably comprises parts of thermoplastic synthetic material and originates, for example, from crushed car bumpers or other crushed car parts. The mixture 2 of particles may likewise originate from crushed household appliances, computers or other parts.

Such a mixture 2 of particles shows, for instance, an average density of 0.3 to 0.8 kg/litre, while the mixture removed 20 of parts of thermoplastic synthetic material has, for instance, an average density of 0.8 to 1.1 kg/litre. The particles may be of any shape or size, although it will be advantageous when the method according to the invention will be applied in a device according to the invention, that the particles of the mixture 2, and especially the particles to be picked up, are of the order of magnitude of between 8 and 30 mm.

Further advantages of the device according to the invention are, that it is of a simple design, available at a low price and that maintenance and cleaning are simple.

The method according to the invention which may be applied by making use of a device according to the invention, and the device according to the invention, designed to make it possible to apply the method according to the invention, are of course not restricted to the embodiments described in the examples, but may comprise likewise variants and combinations of these embodiments.