JP3578636B2 - Plastic sorting method and plastic sorting device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic sorting method and a plastic sorting apparatus for sorting sorted pulverized refuse made of plastic pieces by type.
[0002]
[Prior art]
In recent years, recycling of refuse has been rapidly promoted. By the way, plastics consumed as raw materials for plastic products include vinyl chloride resin (hereinafter referred to as “PVC”), polyethylene resin (hereinafter referred to as “PE”), polypropylene resin (hereinafter referred to as “PP”), It is thought that polystyrene-based resin (hereinafter referred to as “PS”) and methacrylic resin [acrylic resin] (hereinafter referred to as “PMMA”) occupy about 80% of the whole, and the above-mentioned resins occupy most of the waste plastic recovered. Can be In addition, polyethylene terephthalate resin (hereinafter, referred to as “PET”) used as a so-called PET bottle is being independently collected. When recycling these resins, it is important to separate them for each type of resin.
[0003]
Conventionally, there is a plastic sorting apparatus that sorts pulverized plastic pieces. As shown in FIG. 3, this plastic sorting apparatus is a state in which different kinds of resin-based plastics 1 that are sorted and pulverized waste are mixed. And a friction charging device 3 disposed below the outlet of the hopper 2 for frictionally charging the plastic piece 1, and for electrostatically separating the plastic piece 1 charged by the friction charging device 3. And a first separation container 8 and a second separation container 9 for collecting the plastic pieces 1 separated by the electrostatic separation unit. The friction charging device 3 includes a metal cylinder and a metal stirring member mounted on a shaft rotatably provided in the cylinder.
[0004]
The electrostatic separation unit has a metal drum electrode 5 arranged below the frictional charging device 3, and the metal drum electrode 5 is rotated around a horizontal axis in a predetermined direction and is grounded. Further, a brush 10 for scraping off the plastic piece 1 attached to the peripheral surface of the metal drum electrode 5 is arranged on the outer peripheral portion of the metal drum electrode 5. Further, an arc plate high voltage electrode 6 is disposed diagonally above the metal drum electrode 5 in the rotation direction, and the high voltage electrode 6 is connected to a cathode of a high voltage power supply 7. The anode is grounded. With this connection, a rotating ground electrode is formed by the metal drum electrode 5, and a sorting electrostatic field is formed between the high-voltage electrode 6 and the metal drum electrode 5.
[0005]
The operation of the above configuration will be described. The plurality of types of plastic pieces 1 put into the hopper 2 are charged in the friction charging device 3 by agitating the different types of plastic pieces 1 within the cylinder of the friction charging device 3 and frictionally contacting each other.
[0006]
The plastic piece 1 triboelectrically charged in this way is sprayed on the metal drum electrode 5 of the electrostatic separation section G, and the plastic piece 1 negatively charged by the frictional charging device 3 is applied to the metal drum electrode 5. It repels and is sucked by the high voltage electrode 6 and falls into the first separation container 8. The plastic piece 1 charged with a positive charge opposite to the metal drum electrode 5 is adsorbed on the surface of the metal drum electrode 5 and falls into the second separation container 9 by rotation of the metal drum electrode 5, or the brush 10 Is scraped off from the surface of the metal drum electrode 5 and separated, and falls into the second separation container 9.
[0007]
[Problems to be solved by the invention]
The frictional charging device 3 in the above-mentioned conventional plastic sorting device is a device that frictionally charges a plurality of types of plastic pieces 1 by stirring them. In some cases, a charge amount (charge potential) or a polarity required for separation may not be given to the plastic piece 1. In this case, the separation by the electrostatic separation unit that uses the charge of the plastic piece 1 to perform the separation is sufficient. Could not be done.
[0008]
Therefore, an object of the present invention is to provide a plastic sorting method and a plastic sorting device that can solve the above-mentioned problems.
[0009]
[Means for Solving the Problems]
Means for solving the problems in the present invention are a friction charging device for stirring and frictionally charging a plurality of types of pulverized plastic pieces, and separating the frictionally charged plastic pieces below a drop port of the friction charging device. And a separation container for separately collecting the plastic pieces separated by the electrostatic separation section. When the amount of the piece is small, the specific plastic piece is added in a predetermined amount as a frictional charging auxiliary material, so that the specific plastic piece is added between the falling port of the frictional charging device and the electrostatic separation unit, or between the electrostatic separation unit and the separation container. Between the plastic piece and the triboelectric auxiliary material dropped from the triboelectric charging device, a mesh body for capturing the triboelectric auxiliary material is arranged, and the triboelectric auxiliary material captured by the net is removed. Bowed charging device conveying means for returning and conveyed to is provided, on the way of returning the captured frictional charging auxiliary member to the frictional charging device, a cooling means is provided for cooling the frictional charging auxiliary material.
[0010]
Then, a plurality of types of crushed plastic pieces are charged into a frictional charging device by stirring and charged, and the charged plastic pieces are separated by an electrostatic separation unit disposed below the frictional charging device, and the plastic pieces are separated. When the specific plastic pieces to be collected are small and the amount of the specific plastic pieces to be collected is small, when a plurality of types of plastic pieces are stirred by a frictional charging device, A specific amount of the specific plastic piece is added as a frictional charge auxiliary material by a predetermined amount, and the frictional charge auxiliary material of the plastic piece and the frictional charge auxiliary material dropped from the frictional charging device is separated by the electrostatic separation unit. Captured and returned to the triboelectric charging device, or, among the plastic pieces and triboelectric auxiliary materials that fell from the triboelectric charging device, And captured before recovering the separation vessel and separated by releasing unit used repeatedly in the back to the frictional charging device, cooling on the way of returning the frictional charging auxiliary member to the frictional charging device.
[0011]
Further, a frictional charging device for stirring and frictionally charging a plurality of types of crushed plastic pieces, an electrostatic separation unit for separating the frictionally charged plastic pieces below the frictional charging device, Separation containers for separately collecting the plastic pieces separated by the electrical separation unit are provided, and the frictional charging device is provided on a cylindrical body and an inner surface of the cylindrical body to remove a plurality of types of plastic pieces. A plastic layer as a frictional charging auxiliary material used when the amount of a specific plastic piece is small when charged into a triboelectric charging device, and a refrigerant charging portion for charging a refrigerant for cooling the plastic layer is formed of the cylindrical body. It is provided on the outer surface .
[0012]
Then, when a plurality of types of plastic pieces are put into the friction charging device, the plastic pieces and the plastic piece and the plastic layer rub against each other in the cylinder, causing the charge amounts of the plastic pieces to differ, and the refrigerant charged in the refrigerant charging section. This suppresses a rise in the temperature of the plastic layer.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described. As shown in FIG. 1, a plastic sorting apparatus S according to the first embodiment of the present invention includes a hopper 2 that inputs a plurality of different types of plastic pieces (sorted and crushed garbage) 1 of different resin systems, A friction charging device 3 disposed on the outlet 2a side of the hopper 2 for frictionally charging the plastic pieces 1 by stirring; and a plurality of frictionally charged plastic pieces 1 disposed below the friction charging device 3 and frictionally charged. And a first separation container 8 and a second separation container 9 for collecting the plastic pieces 1 electrostatically separated by the electrostatic separation unit G by type. ing.
[0014]
The electrostatic separation unit G includes a metal drum electrode 5 disposed below a drop port 16 of the frictional charging device 3, a high-voltage electrode 6 disposed obliquely above the metal drum electrode 5, and a metal drum electrode 5. And a brush 10 for scraping off the plastic piece 1 adhered to the peripheral surface of the metal drum electrode 5 and disposed below the metal drum electrode 5. The metal drum electrode 5 is rotatable in a predetermined direction around a horizontal axis and is grounded. The high voltage electrode 6 is connected to a cathode of a high voltage power supply 7, and the anode of the high voltage power supply 7 is grounded. By this connection, a rotating ground electrode is formed by the metal drum electrode 5, and a sorting electrostatic field is formed between the high-voltage electrode 6 and the metal drum electrode 5.
[0015]
The first separation container 8 and the second separation container 9 are arranged below the metal drum electrode 5 in the rotation direction of the metal drum electrode 5, and both the first separation container 8 and the second separation container 9 are opened upward. are doing.
[0016]
An inclined guide plate 15 for guiding the plastic piece 1 charged by the friction charging device 3 and dropped from the friction charging device 3 to the metal drum electrode 5 is disposed below the drop opening 16 of the friction charging device 3. A base end of a net 17 for catching a friction charging auxiliary material 21 described below, which has been charged by the friction charging device 3 and dropped from the friction charging device 3, is disposed between the falling port 16 of the device 3 and the inclined guide plate 15. ing. The mesh body 17 is provided to be inclined in the direction opposite to the inclined guide plate 15 and includes a vibration device (not shown). The tip of the mesh body 17 cools the frictional charging auxiliary material 21 whose temperature has been increased by use. To the cooling means 18 side.
[0017]
As shown in the drawing, the cooling means 18 includes a cooling container 19 to which the net 17 is connected, and a cooling liquid (for example, ethyl alcohol is used) for cooling the triboelectric auxiliary material 21 in the cooling container 19. The spray gun 20 includes a spray gun 20 for blowing the coolant 18a from the container 18b and a pump 21 for pumping the coolant 18a to the spray gun 20.
[0018]
In addition, a conveyor (an example of a transporting unit) (not shown) for transporting the frictional charging auxiliary material 21 captured by the net 17 and cooled by the cooling unit 18 to the frictional charging device 3 is provided.
[0019]
Next, a plastic sorting method in the plastic sorting apparatus S having the above configuration will be described. The plurality of types of plastic pieces 1 are put into the friction charging device 3 from the hopper 2 in a mixed state, and are charged to either plus or minus according to the charging sequence according to the type. When a plurality of types of plastic pieces 1 are charged into the hopper 2 and frictionally charged, if the amount of the specific plastic piece 1 (for example, PVC) to be collected is small, the specific plastic piece 1 is frictionally charged. A predetermined amount is added as the auxiliary material 21. Note that the added triboelectric auxiliary material 21 is formed in a larger area than the other plastic pieces 1.
[0020]
Then, the plurality of types of plastic pieces 1 put into the friction charging device 3 are agitated in the friction charging device 3 and rub against each other. At this time, the plastic piece 1 to be agitated is positively or negatively charged by the addition of the frictional charging auxiliary material 21 and sufficiently charged, respectively, so that the charged plastic piece 1 and the frictional charging auxiliary material 21 are added. Fall from the falling port 16 of the frictional charging device 3. The plastic piece 1 dropped from the drop opening 16 passes through the mesh of the mesh body 17 and is scattered on the metal drum electrode 5. Then, the plastic piece 1 charged with the negative charge by the frictional charging device 3 is repelled by the metal drum electrode 5, is sucked by the high-voltage electrode 6, and falls into the first separation container 8. The plastic piece 1 charged with a positive charge opposite to the metal drum electrode 5 is adsorbed on the surface of the metal drum electrode 5 and falls into the second separation container 9 by rotation of the metal drum electrode 5, or the brush 10 Is scraped off the surface of the metal drum electrode 5 and falls into the second separation container 9. For example, PVC is negatively charged and falls into the first separation container 8.
[0021]
On the other hand, the frictional charging auxiliary material 21 that has fallen from the drop opening 16 of the frictional charging device 3 is formed in a larger area than the other plastic pieces 1, so that the frictional charging auxiliary material 21 does not fall off from the eyes of the net 17 and falls on the net 17. Captured. Then, since the mesh body 17 is inclined, it is moved into the cooling container 19 of the cooling means 18 by driving of the vibration device, and the spray liquid 20 is supplied from the spray gun 20 to the frictional charging auxiliary material 21 in the cooling container 19. Is blown, the frictional charging auxiliary material 21 whose temperature has increased due to friction with the other plastic pieces 1 is cooled to zero degree or less, and is returned to the frictional charging device 3 by driving the conveyor.
[0022]
Then, when plastic sorting is subsequently performed, it is not necessary to newly add the frictional charging auxiliary material 21 to the frictional charging device 3, and the cooled frictional charging auxiliary material 21 is reused in the frictional charging device 3, In the same manner as described above, different types of plastic pieces 1 are frictionally charged in the frictional charging device 3 to be positively or negatively charged, and at the same time, the charge amounts of the plastic pieces 1 are made different from each other so that a unique charge amount (charged voltage) is obtained. Accordingly, the plastic piece 1 can be reliably separated by the electrostatic separation part G and collected in the first separation container 8 and the second separation container 9.
[0023]
As described above, according to the first embodiment of the present invention, when the different types of plastic pieces 1 are stirred in the frictional charging device 3, the specific plastic pieces 1 to be collected in the frictional charging device 3 are removed. By adding and stirring as the triboelectric charge assisting material 21, the amount of charge of the plastic piece 1 to be recovered and the other plastic piece 1 can be made different, so that a plurality of types of plastic pieces 1 are mixed. However, it is possible to reliably recover the specific plastic piece 1 therefrom. In addition, it is conceivable that PET is negatively charged similarly to PVC and falls into the first separation container 8 in a charging sequence, but this can be dealt with by changing the voltage applied to the sorting electrostatic field. .
[0024]
It is also known that, when the same material is charged by friction, the charging characteristics change as the friction is repeated. For example, when one of the ebonite bars is kept stationary and the other is rubbed against it, the other is initially charged positively, but when repeatedly rubbed, it is negatively charged. This is considered to be because the same portion of the ebonite rod is rubbed, so that the temperature rises and distortion occurs.
[0025]
However, in the first embodiment of the present invention, since the frictional charging auxiliary material 21 is cooled by the cooling means 18 and rubs against the other plastic piece 1, even if the frictional charging auxiliary material 21 is used repeatedly, As a result, the change in polarity of the triboelectric charge assisting material 21 can be prevented, and it can be repeatedly used without adversely affecting the stirring with the other plastic pieces 1.
[0026]
By the way, if PVC, PE, PP, PS and PET with a large amount of recovery are arranged in the order of charging, PS → PE → PP → PET → PVC from the side that is more likely to be positively charged (There are also documents showing PP → PVC → PET) And are arranged on the side that is easily charged negatively. Here, if the PP located in the middle order is selected as the reference plastic material and another plastic material is rubbed against the reference plastic material made of PP, a large number of positive charges are charged in the order of PE <PS, and Is hardly charged, and more negative charges are charged in the order of PET <PVC. In this way, by selecting the plastic in the middle rank of the charging train as the reference plastic material, the amount of charge can be made different for each type of the mixed plastic pieces 1.
[0027]
Therefore, using PE, PP, PS, PET, and PVC as types of the plastic pieces 1, tests of the recovery rate and the recovery purity were performed. In this test, the weight ratio of the plastic piece 1 was
PE: PP: PS: PET: PVC = 4: 2: 2: 1: 1
A predetermined amount of PVC was added as the frictional charge assisting material 21 (50% by weight as the frictional charge assisting material 21 with respect to the total weight of the mixed plastic pieces 1). As a result, a recovery rate and a recovery purity of 90% or more were obtained, and the triboelectric auxiliary material 21 could be used for a long time.
[0028]
In the first embodiment, the mesh body 17 is disposed between the frictional charging device 3 and the metal drum electrode 5, but the present invention is not limited to this. It may be configured to be disposed between the two separation containers 9, the frictional charging auxiliary material 21 may be captured at this position, the frictional charging auxiliary material 21 may be cooled by the cooling unit 18, and returned to the frictional charging device 3. In this case, the same operation and effect as those of the first embodiment can be obtained.
[0029]
Next, a second embodiment of the present invention will be described with reference to FIG. In the first embodiment described above, the frictional charging auxiliary material 21 captured by the net 17 after the frictional charging is cooled by the cooling means 18 provided separately from the frictional charging device 3, but in the second embodiment of the present invention, Instead of the cooling means 18 provided separately from the frictional charging device 3, a cooling means 25 is provided in the frictional charging device 3.
[0030]
In the frictional charging device 3 according to the second embodiment of the present invention, the outer cylinder 26, the inner cylinder 27 disposed inside the outer cylinder 26, and the inner surface (inner surface side) of the inner cylinder 27 are applied by coating. Then, when a plurality of types of plastic pieces 1 are put into the triboelectric charging device 3, a plastic layer 28 (specific plastic material) as a triboelectric charging auxiliary material 21 used when the amount of the specific plastic pieces 1 to be collected is small. And the cooling means 25 is used. The cooling means 25 includes a cooling liquid filling portion 29 which is a gap between the outer cylinder 26 and the inner cylinder 27, and a cooling liquid 30 (coolant) filled in the cooling liquid filling portion 29 to cool the plastic layer 28. As an example, ethyl alcohol is used, and the ethyl alcohol is controlled at, for example, −40 ° C.), and a cooler 31 for the cooling liquid 30 inserted into the wall surface on the outer cylinder 26 side. Further, the frictional charging device 3 includes a stirring rod member 33 radially arranged on a rotation shaft 32 that passes through the center of the wall surface on the inner cylinder 27 side, and a drive motor 34 for rotating the stirring rod member 33. have.
[0031]
An intake 35 communicating with the outlet 2a of the hopper 2 is provided on one side of the upper portion of the friction charging device 3, and an intake lid 36 for opening and closing the intake 35 is attached to the opening / closing motor 37. A drop port 16 is formed on the other side of the lower portion of the frictional charging device 3, and an adjustment lid 38 for opening and closing the drop port 16 is attached to the adjustment motor 39. Other configurations are the same as those in the first embodiment.
[0032]
In the second embodiment of the present invention, the plural kinds of plastic pieces 1 taken into the friction charging device 3 from the inlet 35 by driving the opening / closing motor 37 to open the inlet cover 36 are driven by the drive motor. The plastic pieces 1 are agitated by the agitating rod member 33 rotated by the driving of the plastic pieces 34, and the plastic pieces 1 and the plastic layer 28 rub against each other. At this time, since the amount of the specific plastic piece 1 is supplemented by the plastic layer 28, the entire plastic piece 1 is positively or negatively charged and is charged to a different charge amount.
[0033]
By the way, when the plastic piece 1 is agitated in the inner cylinder 27, the plastic layer 28 and the plastic piece 1 are rubbed. However, the cooling means 25, that is, the cooling liquid filling portion 29 which is a gap between the outer cylinder 26 and the inner cylinder 27 is formed. Since the plastic layer 28 is cooled by the filled cooling liquid 30, the generation of frictional heat of the plastic layer 28 (and the plastic piece 1) can be suppressed, and the temperature rise of the plastic layer 28 can be suppressed. Therefore, since the thermal distortion of the plastic layer 28 is suppressed and the polarity of the plastic layer 28 is prevented from being changed, the plastic piece 1 can be repeatedly used for a long time without adversely affecting the polarity when stirring the plastic piece 1. it can.
[0034]
Then, by driving the adjustment motor 39 to open the adjustment lid 38, the plastic piece 1 continuously or batchwise falls to the electrostatic separation portion G, and is similar to the first embodiment described above. The specific plastic piece 1 can be collected.
[0035]
【The invention's effect】
As is evident from the above description, the present invention, when the amount of a specific plastic piece to be collected is small, when a plurality of types of plastic pieces are charged into the triboelectric charging device, the specific plastic piece is subjected to a triboelectric charging auxiliary material. As only a predetermined amount is added, the charge amount of different types of plastic pieces is changed, thereby reliably performing separation in the electrostatic separation unit, and a specific plastic piece can be reliably collected and added. Capture the frictional charge auxiliary material by the electrostatic separation unit and return it to the triboelectric charging device, or capture the frictional charge auxiliary material by the electrostatic separation unit and collect it in the separation container before friction. It can be used repeatedly by returning it to the charging device, and by cooling the captured triboelectric auxiliary material while returning it to the triboelectric charging device, changes in the polarity of the triboelectric charging auxiliary material can be suppressed, and the characteristics can be stably maintained for a long time. The piece of plastic can be reliably recovered.
[0036]
In addition, when a plurality of types of plastic pieces are applied to the frictional charging device, the cylinder is applied to a frictional charging device for agitating and frictionally charging the plurality of types of plastic pieces. Since a plastic layer as a triboelectric charge assisting material used when the amount of a specific plastic piece is small and a refrigerant filling portion for filling a refrigerant for cooling the plastic layer are provided, the plastic layer is cooled by the refrigerant. This makes it difficult for frictional heat to be generated in the plastic layer when the plastic piece is agitated in the cylinder, and suppresses the temperature rise of the plastic layer to suppress distortion of the plastic layer, thereby preventing a change in the polarity of the plastic layer. Therefore, the plastic piece can be repeatedly used for a long time without adversely affecting the stirring of the plastic piece.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing an overall configuration of a plastic sorting device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of a frictional charging device according to a second embodiment of the present invention.
FIG. 3 is a schematic view showing the entire configuration of a conventional plastic sorting apparatus.
[Explanation of symbols]
1 plastic piece 1
2 Hopper 3 Friction charging device 3
5 Metal Drum Electrode 6 High Voltage Electrode 8 First Separation Container 9 Second Separation Container 15 Inclined Guide Plate 17 Mesh 18 Cooling Means 21 Friction Charging Aid Material 26 Outer Cylinder 27 Inner Cylinder 28 Plastic Layer 25 Cooling Means 29 Coolant Filling Unit Reference Signs List 30 cooling liquid 31 cooler 33 stirring rod member G electrostatic separation unit S plastic sorting device

Claims (3)

A plurality of types of crushed plastic pieces are charged into a friction charging device by stirring and charged, and the charged plastic pieces are separated by an electrostatic separation unit disposed below the friction charging device, and the plastic pieces are separated. When the amount of the specific plastic pieces to be recovered is small, the specific plastic pieces should be collected separately in a container. A predetermined amount of the plastic piece is added as a frictional charging auxiliary material, and among the plastic pieces and the frictional charging auxiliary material dropped from the frictional charging device, the frictional charging auxiliary material is captured by the electrostatic separation unit before being separated. Return to the triboelectric charging device, or of the plastic pieces and triboelectric auxiliary material dropped from the triboelectric charging device, Plastic sorting method characterized in that apart to capture before recovering the separation vessel was returned to the frictional charging device and used repeatedly, cooled in the course of returning the frictional charging auxiliary member to the frictional charging device. A friction charging device for stirring and frictionally charging a plurality of types of crushed plastic pieces, and an electrostatic separation unit for separating the frictionally charged plastic pieces below a drop port of the friction charging device; A separation container for separately collecting the plastic pieces separated by the electrostatic separation unit, and when a plurality of types of plastic pieces are put into the triboelectric charging device, when the amount of the specific plastic pieces is small, the What is claimed is: 1. A plastic sorting apparatus in which a specific plastic piece is added by a predetermined amount as a frictional charging auxiliary material, wherein said plastic sorting apparatus includes a frictional charging device between a falling port and an electrostatic separation unit, or a static separation unit and a separation container. Between the plastic pieces and the triboelectric auxiliary material that have fallen from the triboelectric charging device, a mesh body for capturing the triboelectric auxiliary material is disposed, and the triboelectric auxiliary material captured by the net is removed. A transporting means for transporting and returning the frictionally charged auxiliary material to the frictional charging device; and a cooling means for cooling the frictionally charged auxiliary material while returning the captured frictionally charged auxiliary material to the frictional charging device. Sorting device. A frictional charging device for stirring and frictionally charging a plurality of types of crushed plastic pieces; an electrostatic separation unit for separating the frictionally charged plastic pieces below the frictional charging device; A separation container for separately collecting the plastic pieces separated by the part is provided, and the frictional charging device is provided on the inner surface of the cylindrical body and the cylindrical body to frictionally charge a plurality of types of plastic pieces. A plastic layer used as a triboelectric auxiliary material used when the amount of a specific plastic piece is small when put into the device, and a refrigerant filling portion for filling a refrigerant for cooling the plastic layer is provided on the outer surface of the cylindrical body. plastic sorting apparatus being characterized in that provided.

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