DE10140241A1 - Friction electrification device for plastic and plastic sorting system using the device - Google Patents

Abstract

An apparatus for electrostatically charging plastic for electrostatically charging various types of plastic is proposed, the apparatus comprising: a housing (22) arranged in the longitudinal direction and having a plastic supply section (21) arranged upstream and a plastic removal section (23), which is provided downstream, and a movement screw (27), which is rotatably arranged in the housing (22) to move the plastic parts and electrically charge them by friction. The inner wall of the housing (22) is designed as a cylinder with a hexagonal cross section in order to create a deposit layer of plastic parts in the gap between the inner wall of the housing (22) and the movement screw (27). This improves the frictional contact between the plastic parts in order to increase the electrostatic charge.

Description

The present invention relates to an electrical device Charging or friction electrification of plastic to plastic parts or plastic waste material that is produced during the manufacture of Plastic products have been delivered or recycled plastic parts Sort plastic waste that is collected for recycling. Farther The invention relates to a plastic sorting system for sorting Plastic parts.

Because of the recent strong growth of recycling are electrostatic separation plastic sorting devices proposed that sort different types of shredded plastic parts, by rubbing them together to be electrically charged and by the different types of friction-charged Plastic parts are separated and sorted by the polarities and the different degrees of charging can be used.

An electrification device for electrically charging Plastic parts, such a sorting device with electrostatic Separation is supplied is in Japanese laid-open publication 10- 24251, which u. a. to the inventor of the present invention declining. This device comprises a cylindrical, radially arranged one Electrification tank with a rotating shaft that is in an axial Section is provided and which has a larger number of stirring blades has, in which the plastic parts by a feed section which at the Top of the container is designed to be fed, and from which the Plastic parts are removed via a discharge section on the floor.  

Conventional electrification devices both rub very effectively the stirring blades as well as the inner surface of the electrification tank against the plastic parts, but the plastic parts themselves are not very effective and not rubbed against each other sufficiently. Accordingly the plastic parts can not be sufficiently up to their Saturated state, and so insufficient Electrified plastic parts cannot cleanly match each other their types are separated. Even if they're in the Plastic sorting device with electrostatic separation introduced , it is impossible to classify the plastic parts exactly, which leads to an inaccuracy in the separation.

Accordingly, it is an object of the present invention to achieve the above. Problem too solve by creating a plastic friction electrification device is that the divided plastic parts different enough Kind can charge up to their saturated state and accordingly that Can separate parts exactly according to their types, as well as a Propose plastic sorting system that this device for uses electrostatic charge from plastic.

The charging device for electrical charging of plastic Friction base according to claim 1 comprises a housing which extends in the longitudinal direction is aligned and has a plastic feed section upstream and a plastic removal section downstream, and one Conveyor screw which is rotatably arranged in the housing around the To transport plastic parts and electrostatically charge them by friction, the housing as a cylinder in the form of a polygon between a triangle or a dodecagon or a pentagon.

In the above Education is the horizontal cross section of an inner wall of the Housing like a polygon between a triangle and a dodecagon  formed so that the plastic parts moved by rotation one Experience resistance from the angular sections of the polygon and thus in the gap between the screw and the housing remain, so that they form an edge layer of plastic parts. It then rubs it remaining layer of plastic parts against the rotation moving plastic parts, which facilitates friction electrification. Accordingly, the plastic parts are rubbed into each other Brought into contact and thus electrically up to their saturation state charged.

The friction electrification device for plastic according to claim 2 has the same configuration as in claim 1, but still includes a feed screw that is upstream of the motion screw and coaxial is arranged with this and receives a rotational movement, the Ratio of a slope a of the spiral screw blades of the feed screw in Relation to a slope b of the spiral screw blades of the Movement screw in a range between 1 <b / a ≦ 10, and being the Device has pressure loading devices, the opening and Actuate locking members in a direction in which the opening and Closing members are closed, these opening and closing members are provided in the removal section of the housing.

In this training, the front screw has one screw blade Slope a, which is smaller than slope b, and is above the Movement screw arranged with the screw blades of pitch b, so the speed at which the plastic parts during a Rotation of the front screw is lower than that Speed at which the plastic parts during one revolution of the Movement screw are promoted. Accordingly, the Conveyor screw section in principle the plastic parts in a filling status, in which has a retained layer of plastic parts, while the motion screw essentially performs the motion  and frictional contact by forming a gap between the Plastic parts and a retention layer of plastic parts. Furthermore, the pressure loading device causes the opening and Closing devices act as a discharge resistor to some of the Pushing plastic parts back into the case, causing them to reappear be charged electrostatically. That way it does that Pressure loading device possible, arbitrarily set the period, meanwhile the plastic parts are retained, causing it it is possible that the retention time is of a sufficiently large value is set to thereby reduce the static electricity of the plastic parts facilitate.

Here the ratio of the pitch b of the motion screw to the Incline a of the feed screw set to 1 <b / a (where a <b), while a setting of 1 <b / a, the retention layer around the Movement screw is consolidated to prevent column from moving train the plastic parts. As a result, the pressure charging device the pressure via the opening and closing device during operation not set, which prevents the Friction electrification state of the plastic parts is controlled. Farther the ratio of the slope b for the motion screw to the slope a the feed screw at b / a ≦ 10 (b ≦ 10a), because with a ratio from b / a ≧ 10 the plastic parts are usually no longer unloaded.

The plastic friction electrification device according to claim 3 a structure as in claim 2, however, a plurality of fine Holes in the bottom wall and possibly also in a side wall of the housing are provided.

With the above Training becomes fine fragments of conductive material or fine plastic pieces mixed with the plastic pieces and can through the multitude of fine holes in the bottom and the  Side walls of the housing are provided to the outside from the Housing are transported out.

The plastic sorting system according to claim 4 comprises the devices for electrostatic friction charging according to one of claims 1 to 3 and a sorting device with electrostatic separation for separating Plastic parts by types from the removal section of the Plastic electrification device were submitted, the system has a sorting device with electrostatic separation, the one Has drum electrode which is rotated about a horizontal axis when Plastic parts are introduced in the vicinity of the upper section, an opposite electrode from the top of the drum electrode in the downstream direction of the rotation direction of the drum electrode is arranged that a predetermined separation space between one Drum surface and the opposite electrode forms, one High voltage supply for applying a high voltage to both the Drum electrode and the opposite electrode is provided, to form an electrostatic field in the separation space, whereby the plastic parts by type by passing through them Plastic parts can be separated by the electrostatic field by the Falling behavior varies based on polarities and degrees of charging because the polarities and degrees of electrification with the type of plastic vary.

With this training, the device for the electrification of friction Sufficient plastic the plastic parts up to theirs Charge saturation state, which makes it possible for the plastic parts from each other according to their type based on their polarities and their degrees of charging, which vary with the type of plastic parts, separated become.  

The plastic sorting system according to claim 5 comprises a sorting device with corona discharge to separate the conductive material from the Plastic parts, the device for friction charging of plastic after one of claims 1 to 3 for electrical charging by friction of Plastic parts emitted by the device with corona discharge be, and a sorting device with electrostatic separation for Separation of plastic parts by type, which of the unloading section of the Plastic electrification apparatus are delivered, the system a corona discharge device having a drum electrode has, which is rotated about a horizontal axis when the plastic parts in near the top, a plastic discharge electrode, from the top of the drum electrode in the downward direction of the Direction of rotation of the drum electrode is arranged such that it has a predetermined separation space between the drum electrode and the Corona discharge electrode creates, as well as a high voltage supply to apply a high voltage to both the drum electrode and the corona discharge electrode to create a corona discharge field in the Form separation space, which separates the conductive material from the Plastic parts is separated by the plastic parts through the Corona discharge field with different falling lines of the conductive material and the plastic material. The sorting device with electrostatic separation includes a drum electrode that is around a horizontal axis is rotated when the plastic parts near the An opposite electrode inserted from the top Top of the drum electrode in a downward direction of rotation of the Drum electrode is arranged such that a predetermined Separation space between one drum surface and the opposite Electrode forms, with a high voltage supply high voltage both the drum electrode and the opposite electrode creates an electrostatic image in the separation space, whereby the plastic parts are separated from each other according to their type by running the plastic parts through an electrostatic field and  different fall lines based on polarities and degrees of charge have, the polarities and degrees of charge with the Type of plastic vary. The plastic friction device is below the Corona discharge device arranged while the device for electrostatic separation below the device for Friction electrification is arranged for the plastic parts.

In this embodiment, the device for electrification of plastic friction in which the inner wall of the housing has a polygonal horizontal cross section has, below the device for sorting via corona discharge arranged, which removes the conductive materials from the plastic parts be separated, and the device for electrostatic separation, the separates the large number of plastic parts, is below the device for Friction electrification arranged. Accordingly, the following can Operating modes are carried out continuously:

Separation of the metal from the materials to be sorted, e.g. B. shredded recycled plastic parts, which are expected to be metal parts are added, such as. B. circuit parts or waste wires, the metallic Parts included, and sorting of different types of plastic parts by type. Furthermore, the degree of electrical charging of the plastic parts controlled according to the nature of the sorted material, so that the Large number of different types of plastic separated exactly can be. Since the device for the electrification of friction of the Plastic is arranged below the device with corona discharge, and the electrostatic sorting device in turn below the Device for electrostatic friction is arranged, the Sorting device can be made compact.

The invention is described below with reference to the drawing:  

Fig. 1 is a view of an entire structure, which according to the present invention shows an embodiment of a plastic sorting apparatus;

Fig. 2A is the sectional side view according to the present invention shows a device for frictional electrification;

Fig. 2B is a sectional view taken along the line XX shown in Fig. 2A; and

Fig. 3 is a side sectional view of another embodiment of an electrification apparatus in friction base according to the present invention.

An embodiment of the plastic sorting system using the Device for friction charging plastic according to the present Invention will be described with reference to the drawing.

As shown in Fig. 1, this device for sorting plastic sorts materials including, for example, two (or more) into different types of plastic parts (insulating parts) which are obtained by comminution, for example plastic-coated waste wires and copper wire fragments (conductors) which have not been completely removed, and separates and collects the plastic parts by type by separating the copper wire waste from the materials to be sorted and then electrically charging the plastic parts with friction.

The plastic sorting device comprises a device 1 for sorting with the aid of a corona discharge for separating the copper wire waste and the plastic pieces from the materials to be sorted, a device 2 for friction charging in order to charge the plastic parts electrically via friction (if, for example, the plastic parts are polyvinyl chloride - PVC - and polyethylene - PE - contained, they are brought into frictional contact with each other to charge the PVC and the PE according to the electrical order, so that they have negative and positive polarities, respectively, (the charging potential corresponds to the electrical order) and a sorting device 3 with electrostatic sorting for separation and collecting the plastic parts according to their type. In the vertical direction, the device 1 for sorting via corona discharge, the device 2 for friction electrification and the device 3 for electrostatic separation are arranged in this order. The materials to be sorted have already been crushed and have a particle size of 5 mm or less, for example.

The corona discharge sorting device 1 includes a portion 7 for supplying a predetermined amount used for the corona discharge and electrostatic separation, and has a hopper 4 and a feed plate 6 with a vibrating device 5 , with a metallic drum electrode 8 in the direction , as shown by the arrow in the figure, is rotated about a horizontal axis at a predetermined speed, this drum being electrically grounded, a needle-shaped electrode (gorona discharge electrode) 9 , which extends from the top of the drum electrode in the direction of rotation of the drum electrode 8 is arranged such that it forms a predetermined separation space obliquely above the drum electrode 8 , an auxiliary plate-like electrode 10 which is arranged underneath and opposite the needle-shaped electrode 9 , a separation space between the needle-shaped electrode 9 and the auxiliary plate-shaped n electrode has arisen, and a high-voltage supply 13 for applying high voltage between the needle-shaped electrode 9 and the auxiliary plate-shaped electrode 10 and the drum electrode 8 via a variable resistor, in order to form a corona discharge field H between the needle-shaped electrode 9 and the drum electrode 8 , thereby forming a electrostatic field J forms between the auxiliary plate-shaped electrode 10 and the drum electrode 8 .

8 also has the drum electrode, a rotary brush 16 which is arranged on the underside of an outer Umfalzfläche to plastic parts P scrape, which are sucked from the drum electrode 8 and further collecting portions 14 and 15 which are disposed below the electrostatic field J to separated plastic parts Collect P and copper wires M. Furthermore, the collecting section 16 has a static eliminator 17 for neutralizing the charges on the plastic parts P.

The device 2 for friction charging is arranged below the device 1 for sorting via corona discharge and has a feed section 21 which is provided with a metering funnel 19 for receiving the plastic parts P, which are fed from the collecting section 14 of the corona sorting device 1 , and a feed section 20 .

The device 2 for friction charging has a housing 22 which is arranged essentially horizontally and, like a cylinder, for example with a horizontal cross section in hexagonal shape with the same side length, as shown in FIG. 2B. The housing 22 has a supply section 21 which is attached upstream and a discharge section 23 which is attached downstream. Furthermore, the housing has a plurality of fine openings 24 in a bottom surface in order to remove particles such as fine copper particles or finely granulated plastic which are mixed into the plastic parts P, so that the particles discharged from the fine holes into a dispenser such. B. drop a delivery plate 34 and then be fed to the exterior of the device.

The housing 22 has a screw shaft 26 which is provided in an axial arrangement and which is set in rotation by a rotary drive device 25 such as a motor. The screw shaft 26 includes a downstream mounted moving section C and an upstream-mounted supply section D. The portion of the screw shaft 26 which is disposed in the movement section C is provided with a motion screw 27 with helical screw blades 27 B, which have a large pitch b, and the portion of the screw shaft 26 which is arranged in the feed section D is provided with a feed screw 28 which have spiral screw blades 28 A which run in the same direction but with a pitch which is smaller than that of the movement screw 27 . Furthermore, in this embodiment, the ratio b: a of the slopes of the screw blades 27 B and the screw blade 28 A is set to, for example, 7: 1. Furthermore, the motion screw 27 and the feed screw 28 each have substantially triangular gaps between the circumference and the outer circumference and the hexagonal housing 22 . When the plastic parts are rotated, plastic parts are retained in the angled portions, which roughly correspond to the almost triangular gaps and have a high resistance.

A rotational drive device 25 for rotationally driving the motion screw 27 of the friction charging device 2 includes an occupant-controlled electric motor which can vary the speed of rotation of the motion screw 27 depending on the size of the plastic parts, the sorting materials or the difficulty of electrifying the plastic parts. Furthermore, the rotational speed of the movement screw 27 can be set within 200 and 3600 rpm, preferably it is between 200 and 3000 rpm in order to collect the plastic parts at a collection rate of 80% by mass or weight percent or more. As the rotation speed of the motion screw 27 is increased, the degree to which the plastic parts are electrically charged per unit time also increases, but the time period during which the plastic parts are retained in the housing 22 decreases. Accordingly, the rotational speed is preferably in the above range, taking into account the type of plastic parts, the period in which the plastic parts are retained in the housing 22 , and the desired level of electrification.

The housing 22 is provided with an opening part and a closing part 31 which is attached to the unloading section 23 so that it can be opened and closed arbitrarily and which is pivotably supported by a corresponding pivot connection part. On the back of the opening and closing part 31 , a pressure loading device 33 is provided which has a hydraulic cylinder or the like and which can control the removal of the plastic parts by acting on the opening and closing part 31 in the direction of the closing movement. The degree of electrification and the removal of the plastic parts B are controlled on the basis of the pressure exerted on the opening and closing part 31 and on the basis of the rotational speed of the screw.

The pressure applied to the opening and closing member 31 by the pressure loading device 33 to press it in the direction of the closing movement is preferably equal to or less than 0.05 MPa, with the preferred range being between 0.005 and 0.05 MPa , The pressure is too high above 0.05 MPa, so that the plastic parts are melted in between due to the frictional heat.

The electrostatic separation device 3 is arranged below the device 2 for friction charging. The electrostatic-based sorting device 3 includes a feed section 37 which consists of a feed plate 36 with a vibrating device 35 for feeding a certain amount of plastic parts P from a discharge unit 23 of the friction electrification apparatus 2 , a metallic drum electrode 38 which is nearby and below of the device 2 for friction charging, which is rotated in the direction indicated by the arrow in the figure, about a horizontal axis at a given speed and which is electrically grounded, a plate-shaped electrode 39 for electrostatic separation which is separated from the top of the drum electrode 38 is disposed in the downward direction of the rotational direction of the drum electrode 38 so as to obliquely a predetermined separation space above the drum electrode 38 is formed, a high voltage power supply 40 whose negative electrode with the plate-shaped Electrode 39 and its positive electrode is grounded to form a high voltage between the plate-shaped electrode 39 and the drum electrode 38 to form an electrostatic field K for sorting in the separation space, a rotary brush 47 arranged on the bottom of an outer peripheral surface of the drum electrode 38 to scrape plastic parts P sucked by the drum electrode 38 and a collecting portion 41 located below the sorting electrostatic field K to separately collect the plastic parts passing through the sorting electrostatic field K and based on each other Polarities and their degrees of charge have been separated.

The collecting section 41 comprises a first collecting chamber 42 which is arranged below the drum electrode 38 in order to store plastic parts P such as, for. B. PVC separately, which are charged with negative polarity and are sucked and absorbed by the drum electrode 38 , a second collection chamber 43 for separate collection of plastic parts P such. B. PE which are charged with positive polarity and are repelled by the drum electrode 38 , and a third collecting chamber 44 , which is arranged between the first collecting chamber 42 and the second collecting chamber 43 to unseparated plastic parts P such. B. PVC or PE to collect, which have not been charged to a sufficient extent. The first and the second collecting chambers 42 and 43 each have a static eliminator 45 which is arranged in the interior in order to neutralize the plastic parts P.

The third collecting chamber 44 has a transport line 46 which is connected to an unloading opening of the third collecting chamber 44 and which comprises an air tube and i. V. m. the introduction section 20 of the device 2 for friction charging. The transport line 46 leads the undivided plastic parts P, which are collected in the third collecting chamber 44 , back into the introduction section 20 , where they are in turn separated from one another.

The dosing hopper 19 , which is provided between the collecting section 14 of the sorting system via corona discharge and the feed section 21 of the device 2 with friction charging, is provided with a weight sensor 51 and an opening and closing part 50 , which is activated by an opening and closing mechanism 52 , for example one hydraulic cylinder is actuated so as to adjust the opening degree of the metering funnel 19 . For the opening and closing part 50 , a control section 53 outputs a control signal based on an output signal detected by the weight sensor 51 and activates the opening and closing mechanism 52 .

The opening and closing part 31 , which is provided in the unloading section 23 of the device 2 for friction charging, has an angle detection sensor 54 for detecting the angle by which the opening or closing part 31 is opened or closed. The control section 53 calculates the withdrawal based on an output from the angle detection sensor 54 and returns the withdrawn material to the feed control to control the opening and closing device 52 of the dosing hopper 19 , thereby feeding and removing the device 2 Frictional charging is controlled.

The drum electrode 8 of the device 1 for sorting via corona discharge and the drum electrode 38 of the sorting device 3 via electrostatic separation are driven in rotation by a single common drive device (not shown), for example by an electric motor.

In the above-mentioned embodiment, a high voltage is applied to the device 1 with corona discharge with the aid of the device 13 for supplying a high voltage, the drum electrode 8 being used as the positive electrode and the needle-shaped electrode 9 as the negative electrode, so that electrons collide with one another and from one another Disconnect to ionize a gas in a non-uniform electric field, thereby creating a corona discharge, which forms a corona discharge field H between the two electrodes 8 and 9 . Furthermore, a high voltage is applied to the device 1 with corona discharge via the high-voltage supply 13 , the drum electrode 8 being used as the positive electrode and the electrode 10 , which is designed in the form of an auxiliary plate, as the negative electrode downstream, so that an electrostatic field J is formed for sorting , When the materials to be sorted, namely a mixture of the plastic parts P with PVC and PE and copper wire waste M, which are obtained, for example, by destroying plastic-coated waste wires, are fed to the plate 6 , which is vibrated by the vibrating device 5 , the materials become conveyed further on the feed plate 6 and then applied to the surface of the drum electrode 8 .

The drum electrode 8 is rotated to supply the material to be sorted to the corona discharge field H, where the negative corona materials are subjected to the acicular electrode 9 and charged with negative charges.

Of the to be sorted materials, the copper wire wastes M, the negatively charged conductive material is neutralized in contact with the drum electrode 8 by the positive charges of the drum electrode 8 and further provided with positive charging by the drum electrode 8 to be repelled. Thus, the copper wire fragments M fall as they follow this path when they leave the drum electrode 8 and are then collected in the collecting section 15 .

On the other hand, of the materials to be sorted, the plastic parts P, the insulated parts, are provided with a negative charge due to the corona discharge from the needle-shaped electrode 9 and are thus sucked in by the drum electrode 8 or acted upon in the direction of the drum electrode 8 .

Centrifugal force and attractive force act on these plastic parts, and when the latter have reached the electrostatic field J, the attractive force is increased due to the polarization and the electrostatic force acting on them, whereby the plastic parts even if they have negative charge induced by corona discharge insufficient are provided, sucked effectively and moved in the direction of the drum electrode 8 . Thus, the plastic parts P fall into the collecting section 14 while following this path in the vicinity of the drum electrode 8 , or are sucked in and adhere to the drum electrode 8 , the plastic parts P being scratched by the rotary brushes 16 and in the collecting section 14 to be collected.

The plastic parts P, which are collected in the collecting section 14 , have their charges, which are induced by the corona discharge field H, and which are neutralized by the static eliminator 17 .

Then, the plastic parts P which are fed into the metering cylinder 19 of the friction electrification device 2 and then into the inside of the housing 22 through the feed section 20 .

The plastic parts P, which are fed to the inside of the housing 22 , are carried forward by the moving screw 27 of the moving section C while being rotated in accordance with the rotation of the feeding screw 28 of the feeding section D. The plastic parts P are moved and brought into frictional contact with each other due to the rotation of the screws 27 and 28 . At this time, a deposit layer of the plastic parts P is formed in the gap between the motion screw 27 and the housing 22 , and the plastic parts P come into frictional contact with each other within the deposit layer and between the deposit layer and the rotationally moving plastic parts. Some of the plastic parts P are guided to the removal section 23 and pushed back by the opening and closing part 31 and continue to be moved and brought into friction with each other. This frictional contact allows all plastic parts to be electrically charged effectively by friction.

Accordingly, before the plastic parts P are discharged from the removal opening 23 , the PVC is electrically charged with a negative polarity up to a certain charging value, the PE being charged with a positive polarity up to a certain value. Furthermore, particles such as fine copper waste or fine granulated plastic, which are mixed with the materials to be sorted, are released through the fine holes 24 and removed from the housing 22 to the outside via the removal plate 34 .

Further, the frictionally charged plastic parts discharged from the discharge opening 23 of the friction electrification device 2 are fed to the feed plate 36 vibrated by the vibrating device 35 , and then brought from the feed opening 36 to the surface of the drum electrode 38 .

The plastic parts P are sucked by the drum electrode 38 and acted upon in their direction, and the centrifugal force due to the rotation of the drum electrode 38 also acts on them. When the plastic parts P are moved in the direction of the sorting electrostatic field K, the force acting on them is increased due to the polarization, and electrostatic force acts on the plastic parts P. Of these forces, the electrostatic force acts strongly so that the positively electrified PE particles are repelled by the positively charged drum electrode, while they are sucked in by the negatively charged plate-shaped electrode 39 and acted upon in their direction. The plastic particles P thus fall into the second collecting chamber 43 while they follow these tracks when they leave the drum electrode 38 .

On the other hand, the negatively charged PVC is sucked from the positive drum electrode 38 and is acted upon in its direction and thus falls, following this path, when approaching the drum electrode 38 or is sucked from it and stuck to the drum electrode 38, where the PVC of the rotary brush 37 is scraped off and collected in the first collecting chamber 42 .

The PVC collected in the first collection chamber 42 and the PE collected in the second collection chamber 43 are neutralized with their charges by the static eliminators 45 and are therefore uncharged.

The undivided PVC and PE that have not been sufficiently charged are collected in the third collection chamber 44 . The PVC and PE in the third collecting chamber 44 are fed back to the feed section 20 via the transport line 46 , which in turn separates them from one another.

The device for friction electrification with a housing of regular hexagonal cross section according to the present invention was compared to a friction electrification device using a Housing of circular cross-section includes to ensure the separation accuracy for Compare plastics.

As a result, the device according to the present invention has a very high separation accuracy, the PVC collected in the first collecting chamber 42 has a purity of 99.7% by mass (purity = weight of the PVC collected in the first collecting chamber in relation to the weight of the plastic parts) total in the first collection chamber) and a recovery percentage of 99.7% by mass (recovery percentage = weight of the PVC collected in the first collection chamber in relation to the total weight of the PVC supplied), and the PE collected in the second collection chamber has one Purity level of 99.6% by mass and a recovery percentage of 90.5% by mass. In contrast, a device with a friction electrification and a housing with a circular cross section has a lower separation accuracy than the present invention, the PVC had a purity of 99% by mass and a recovery percentage of 81.1% by mass, and the PE had a purity of 97, 2 mass% and a recovery rate of 83.3 mass%.

According to the present embodiment, the casing 22 of the friction charging device 2 is formed from a cylinder having a regular hexagon cross section, so that the moving screw 27 , which is driven in rotation, to move the plastic parts P and rub them against each other, whereby the resistance of the angular sections, which correspond to the gaps between the housing 22 and the movement screw 27 , serves for the plastic parts P to form a deposit layer. Thus, the plastic parts P are brought into frictional contact with one another within the storage layer and the storage layer and the rotationally moving plastic parts P and thus efficiently charged. Furthermore, in the unloading section 23, the pressure loading device 33 supplies pressure to the plastic parts P via the opening and closing part 31 to create a resistance to removal, and some of the plastic parts are pushed back and moved again to facilitate friction charging. As a result, the plastic parts P have sufficient charge to reach their saturation state and are then sorted exactly from one another by the device 3 with the aid of the electrostatic charge which is arranged below the discharge section 23 .

Furthermore, the particles such as fine copper waste or fine granulated plastic, which are mixed into the plastic parts P, which have been separated from the copper wire M via the first sorting device 1 , are drawn off and removed from the fine holes 24 in the housing 22 . This prevents a reduction in the separation accuracy which arises from sparking in connection with the copper waste or from the adhesion of the particulate plastics when the device 3 for sorting via electrostatic separation, which is arranged below the first sorting device 1 , separates the plastic parts P.

Furthermore, the first sorting device, the device 2 for friction charging and the second sorting device 3 are arranged in this order downstream for continuous operation, which enables the following modes of operation to be carried out continuously and effectively:
Separation of plastic parts P from copper wire waste, friction charging of plastic parts P and separation of the two types of plastic P from each other. Furthermore, since these three devices are arranged in the vertical direction, the space required for installing these devices is reduced.

In the above embodiment, the housing 22 is formed from a cylinder with a hexagonal shape in cross section, but it may have a circular outer circumference, as long as the inner wall has a polygonal cross section, such as. B. has a regular hexagon. Furthermore, the housing 22 can be arranged such that the removal section 23 points obliquely upwards in order to increase the discharge resistance.

Furthermore, the feed section of the device 2 for friction electrification has the metering funnel 19 and the feed section 20 arranged separately, but the metering funnel 19 and the feed section 20 can be formed in one piece.

Furthermore, the housing 22 has fine holes 24 in the bottom wall, but the holes can also be formed in the side walls. In order to further increase the movement force of the movement screw 27, a plurality of projections of the surface of the propeller blades 27 can b or the screw shaft may be added 26th

Furthermore, in the rotary drive devices, the drum electrode 8 and the rotary brushes 16 can be moved by a common drive device, and the drum electrode 38 and the rotary brushes 47 can also be moved by a common drive device.

Fig. 3 shows a further embodiment of the device having frictional electrification, in which the screw shaft 26 has a motion screw 27, in which a screw blade 27 is B with a fixed pitch is provided. That is, In this embodiment, the pitch ratio b / a is set to 1, so that the plastic parts come into sufficient contact with one another to obtain a sufficient charge, which can be lower than the pitch ratio of 1 <b / a.

As described above, the devices for friction charging are according to of the present invention and the plastic sorting system that this Device used, designed to plastic parts that are recycled should be sorted by type of plastic.

Claims (5)

1. Device for electrically charging plastic with friction, characterized by :
a housing that is arranged in the longitudinal direction and has a supply section for plastic parts, which is arranged upstream, and
a removal section for plastic parts, which is arranged downstream, and
a movement screw which is rotatably arranged in the housing in order to move plastic parts and to charge them electrically by friction,
wherein the housing is designed as a cylinder with an inner cross section which has the shape of a polygon, the polygon having between three and twelve sides. 2. Device according to claim 1, characterized in that a feed screw is provided upstream of the motion screw and is coaxially aligned with it and driven to rotate,
wherein the ratio a of the spiral screw blades of the feed screw to the pitch b of the spiral screw blades of the motion screw is in a range between 1 <b / a ≦ 10, and
a pressure loading device for loading an opening and closing part in a direction in which the opening and closing part is closed is provided, the opening and closing part being arranged in the unloading section of the housing. 3. Device according to claim 2, characterized in that a Variety of fine holes in the bottom wall and / or one Side wall of the housing are formed. 4. Plastic sorting system with
a device for electrically charging plastic by friction according to one of claims 1 to 3, and
a device for sorting by electrostatic separation for separating plastic parts in the manner of the plastic, which are emitted by the unloading section of the device for electrically charging the plastic,
wherein the device for sorting by electrostatic charge comprises a drum electrode which is rotated about a horizontal axis when the plastic parts are introduced into the region of the top, an opposing electrode which is arranged from the top of the drum electrode in the downstream direction of the drum electrode, that a predetermined separation space is formed between the drum electrode and the opposite electrode, and a high voltage supply applies a high voltage to both the drum electrode and the opposite electrode to form an electrostatic field in this separation space, whereby the plastic parts are separated from each other according to their plastic type by the plastic parts pass through the electrostatic field on different traces of fall due to their polarities and the electrostatic charge, these polarities and electrostatic charges mi t vary the type of plastic. 5. Plastic sorting system with
a sorting device with corona discharge for separating conductive material from the plastic parts,
an apparatus for electrically charging the plastic by friction according to any one of claims 1 to 3 for electrically charging the plastic parts emitted by the corona discharge device, and
a device for sorting on electrostatic separation for separating the plastic parts, which are emitted from the discharge section of the device for electrostatic charging, according to the type of plastic,
wherein the corona discharge sorting device has a drum electrode which is moved about a horizontal axis when plastic parts are inserted into the vicinity of the top, a corona discharge electrode is arranged from the top of the drum electrode in the direction downstream of the direction of rotation of the drum electrode such that there is a predetermined separation space between the Drum electrode and the corona discharge electrode, and a high voltage supply applies a high voltage to both the drum electrode and the corona discharge electrode to form a corona discharge field in the separation space, whereby the conductive material is separated from the plastic parts by running the plastic parts through the corona discharge field and different falling lines of the conductive material and the plastic parts,
wherein the device for sorting by electrostatic charge comprises a drum electrode which is rotated about a horizontal axis when the plastic parts are introduced into the region of the top, an opposing electrode which is arranged from the top of the drum electrode in the downstream direction of the drum electrode, that a predetermined separation space is formed between the drum electrode and the opposite electrode, and a high voltage supply applies a high voltage to both the drum electrode and the opposite electrode to form an electrostatic field in this separation space, whereby the plastic parts are separated from each other according to their plastic type by the plastic parts pass through the electrostatic field on different traces of fall due to their polarities and the electrostatic charge, these polarities and electrostatic charges mi t vary the type of plastic, and
the device for friction charging the plastic is provided below the device for sorting via corona discharge, while the device for sorting on an electrostatic separation basis is arranged below the device for friction electrification.