JP3756038B2 - Plastic sorting equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plastic sorting facility for sorting plastic pieces to be recycled, particularly plastic pieces containing foamed plastic, by electrostatic separation.
[0002]
[Prior art]
Conventionally, an electrostatic sorting apparatus that sorts plastic pieces to be recycled according to material is one that separates and collects materials according to the charge amount and polarity when the plastic pieces are frictionally charged. In this plastic sorting device, a frictional charging device causes frictional contact between the material to be rubbed and the plastic piece for charging, and gives the plastic piece a charge necessary for separation. In the electrostatic separation device, the plastic piece is put into an electrostatic field formed between the drum electrode and the high voltage electrode, and the plastic piece charged to the (+) polarity is attracted to the drum electrode on the (−) side. In addition to drawing the fall trajectory, the plastic piece charged to the (−) polarity is drawn and separated from the drum electrode on the (−) side, thereby being separated and collected in separate trays.
[0003]
[Problems to be solved by the invention]
By the way, when foamed plastic is mixed in the plastic piece, the bulk specific gravity is small compared to other plastic pieces, so it floats in the triboelectric charging device, and contact contact cannot be obtained sufficiently, and the charge amount Has a problem that the separation accuracy by the electrostatic sorting device is lowered.
[0004]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a plastic sorting facility that can be separated with high accuracy by an electrostatic sorter even when foamed plastic is mixed in a plastic piece.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is directed to an electrostatic sorting device that sorts plastic pieces using static electricity, and a frictional charge that frictionally charges a plastic piece to be supplied to the electrostatic sorting device. A plastic sorting facility equipped with a device, wherein the plastic piece is heated in a range of 150 ° C. to 180 ° C. for 1 to 3 minutes in a supply portion that supplies the plastic piece to the friction charging device, and foaming contained in the plastic piece A heating device for heat-shrinking the plastic pieces is provided.
[0006]
According to the above configuration, the foamed plastic piece is heated in the range of 150 ° C. to 180 ° C. for 1 to 3 minutes, and effectively contracted by heat without melting, thereby increasing the bulk specific gravity. The foamed plastic piece can be prevented from being lifted, and can be brought into frictional contact like other plastic pieces and can be charged enough, so it can be separated and collected with high precision by an electrostatic sorter. Separation accuracy is not lowered by the foamed plastic piece contained .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Here, an embodiment of the plastic sorting equipment according to the present invention will be described with reference to FIGS.
[0012]
As shown in FIG. 1, this plastic sorting equipment is separated according to the material by the triboelectric charging device 1 for charging the plastic piece in contact and the polarity and the charge amount of the plastic piece in the electrostatic field 10 formed between the electrodes 5 and 6. the electrostatic sorting device 2 for, and a deployed heating device 4 between the hopper 3 for supplying plastic pieces and charging friction device 1.
[0013]
The electrostatic sorting device 2 includes a metal drum electrode 5 disposed below the frictional charging device 1 so as to be rotatable around a horizontal axis, and a high distance disposed at a predetermined distance obliquely above the drum electrode 5. A voltage electrode 6 and a brush 7 for scraping off a plastic piece adhering to the outer peripheral surface of the metal drum electrode 5 are provided. The drum electrode 5 is provided in a predetermined direction in the direction of an arrow around a horizontal axis by a rotary drive device (not shown). Driven at speed. The drum electrode 5 is grounded, for example, the anode of the high-voltage power supply device 8 is grounded, and the cathode is connected to the high voltage electrode 6, whereby the electrostatic field for sorting is provided between the high voltage electrode 6 and the drum electrode 5. 10 is formed. The first recovery chamber 9A to the third recovery chamber 9C partitioned by the separation plate 9a are disposed below the drum electrode 5, and the plastic pieces that have passed through the electrostatic field 10 can be separated and recovered by type.
[0014]
As shown in FIG. 2, the heating device 4 includes a belt conveyor 11 that is a conveying device in which an endless metal belt 11a is wound between sprockets, and a metal tube 12 that surrounds the metal belt 11a. 13 is provided with a heating furnace 14 around which a plastic piece conveyed by the metal belt 11a is heated in the range of 150 ° C. to 180 ° C. for about 1 to 3 minutes. 15 is provided. If the heating temperature and the heating time exceed this range, the plastic pieces begin to soften and stick to each other. On the other hand, if the heating temperature and the heating time are below this range, shrinkage of the foamed plastic piece is insufficient. This temperature control device 15 has a power source 16 arranged in the metal tube 12 and a switch 17 interposed in the wiring connecting the heater 13, and puts the plastic piece conveyed by the metal belt 11a within a predetermined temperature range. It is comprised with the temperature controller 18 which controls heating.
[0015]
As shown in FIG. 3, the friction charging device 1 has a supply port 23 having a charging chute 22 formed on the upper surface of a standing cylindrical charging container 21, and a discharge port 24 that can be opened and closed by a shutter device 25 on the bottom surface. Is formed. A stirring shaft 26 disposed at the axial center of the charging container 21 is rotatably provided by a stirring drive device 27, and a stirring blade 28 is attached to the stirring shaft 26. Further, at least the surfaces of the charging container 21, the stirring shaft 26, and the stirring blade 28 are covered with a resin to be rubbed. The resin to be rubbed is selected to be located in the middle of the electrification row of the plastic piece to be separated, and is configured to impart a charge of opposite polarity when the plastic piece to be separated comes into contact. ing.
[0016]
In the above configuration, the plastic piece supplied from the supply hopper 3 to the heating device 4 passes through the metal tube 12 while being conveyed by the belt conveyor 11 and is heated by the heating atmosphere, whereby the foamed plastic piece is thermally contracted. Thus, the bulk specific gravity is increased and becomes the same as that of plastic pieces other than the foamed type. As a result, even if the charging blade 21 is inserted into the charging container 21 of the friction charging device 1 and the stirring blade 28 is swung, the inner peripheral surface of the charging container 21, the stirring blade 28, and the plastic pieces are brought into contact with each other without being lifted. The whole is sufficiently triboelectrically charged. Further, since the inner surface of the container main body 21 and the surface of the stirring blade 28 are covered with the resin to be rubbed, the electric charge charged in the plastic piece does not escape.
[0017]
Then, it is sent from the discharge port 24 to the electrostatic field 10 between the high voltage electrode 5 and the metal drum electrode 4, and the induced charge is (+) away from the drum electrode 4 that is grounded as the plastic piece having a larger amount of charge, On the contrary, as the induced charge is (−) and the charge amount is larger, it is adsorbed to the drum electrode 4 and separated into the first collection chamber 9A to the third collection chamber 9C and dropped, and the plastic pieces are collected by type.
[0018]
(Example)
Here, a mixture of a plastic piece made of PVC resin and another plastic piece containing polystyrene foam PS (the content of PVC resin is 2%) from the hopper 3 to the heating device 4, the friction charging device 1, and the electrostatic separation device 2 And then separated. As a result, the foaming plastic piece is heated and contracted by the heating device 4, and the phenomenon of floating in the charging container 21 does not occur. When the foamed plastic piece was not heat-heat-shrinkable, the PVC content was 0.9%, whereas when it was heat-shrinked, the PVC content was 0.5%, and the PVC content was Diminished. Here, PVC content = PVC weight contained in the separated plastic piece / total weight of the separated plastic piece. In addition, this PVC content rate = 0.5 value is a numerical value that is said to reduce the corrosion of the furnace and the amount of dioxins generated when plastic is used as the recycled fuel.
[0019]
According to the above-described embodiment, the plastic piece before the supply of the friction charging device 1 is introduced into the heating device 4 and heated, whereby the foamed plastic piece is heat-shrinked to increase the bulk specific gravity and thereby the friction The foaming plastic piece is prevented from floating in the charging device, and like the other plastic pieces, it can be brought into sufficient frictional contact with the resin for friction and can be charged sufficiently. Therefore, the separation accuracy by the foamed plastic piece is not lowered.
[0020]
FIG. 4 shows another embodiment of the heating device, in which a heating furnace 31 using hot air is provided instead of the heating furnace using an electric heater. That is, one or a plurality of air nozzles 33 are arranged in the furnace wall 32 surrounding the metal belt 11 a of the belt conveyor 11, and hot air heated by the heat exchanger 35 from the blower fan 34 is supplied to the air nozzle via the flow rate adjustment valve 36. 33. And the heating temperature control apparatus 39 which operates the flow volume adjustment valve 36 by the temperature controller 38 based on the detected value of the temperature sensor 37 arrange | positioned at the exit of the heating furnace 31, and controls the heating state of a plastic piece is provided. Yes. Of course, the hot air is blown so that the foamed plastic piece is not blown away.
[0021]
【The invention's effect】
As described above, according to the present invention , the foamed plastic piece is heated in the range of 150 ° C. to 180 ° C. for 1 to 3 minutes, and effectively contracted by heat without melting to increase the bulk specific gravity. triboelectric charge to prevent floating of the expanding system plastic pieces in the apparatus, it is possible to similarly frictional contact with other plastic pieces, it is possible to impart sufficient charge, accurately separated and recovered by electrostatic sorting device The separation accuracy is not reduced by the foamed plastic piece contained in the plastic piece .
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of an electrostatic sorting equipment according to the present invention.
FIG. 2 is a configuration diagram showing the heating device.
FIG. 3 is a longitudinal sectional view showing the friction charging device.
FIG. 4 is a configuration diagram showing another embodiment of the heating device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Friction charging device 2 Electrostatic sorting device 4 Heating device 5 Drum electrode 6 High voltage electrode 8 High voltage power supply devices 9A-9C First to third recovery chambers 10 Electrostatic field 11 Belt conveyor 14 Heating furnace 21 Charging vessel 26 Agitation shaft 28 Agitation Wings

Claims (1)

A plastic sorting facility comprising an electrostatic sorting device that sorts plastic pieces using static electricity, and a friction charging device that frictionally charges a plastic piece to be supplied to the electrostatic sorting device by contact,
The supply unit that supplies the plastic piece to the friction charging device is provided with a heating device that heats the plastic piece within a range of 150 ° C. to 180 ° C. for 1 to 3 minutes to thermally contract the foamed plastic piece contained in the plastic piece. Plastic sorting equipment characterized by that.

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