JP2001276660A - Plastic sorting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate and recover plastic pieces including foamed plastic pieces with good accuracy. SOLUTION: The plastic sorting equipment comprises an electrostatic sorter 2 for classifying the plastic pieces by utilizing static electricity and a triboelectrification device 1 which triboelectrifies the plastic pieces supplied to this electrostatic sorter 2 by contacting. A supply section for supplying the plastic pieces to the electrostatic sorter 2 is provided with a heater 4 for thermally shrinking the foamed plastic pieces included in the plastic pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic sorting apparatus for sorting plastic pieces to be recycled, particularly plastic pieces containing foamed plastics, by electrostatic separation.

[0002]

2. Description of the Related Art Conventionally, an electrostatic sorting apparatus for sorting plastic pieces to be recycled by material is one in which plastic pieces are separated and collected according to the amount of charge and polarity when frictionally charged the plastic pieces. In this plastic sorting device, a frictional charging device frictionally contacts a material to be frictioned and a plastic piece to charge the plastic piece, and imparts a charge required for separation to the plastic piece. Then, 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 (+)-polarized plastic piece is attracted to the (-) drum electrode. In addition to drawing a falling locus to be drawn, the plastic piece charged to the (-) polarity is separated and collected on separate trays by drawing a falling locus repelling the (-) side drum electrode.

[0003]

By the way, when a foamed plastic is mixed in a plastic piece, since the bulk specific gravity is smaller than that of other plastic pieces, the plastic piece floats up in the frictional charging device, and the contact contact is made. There is a problem that the separation accuracy by the electrostatic sorting device is reduced because the charge amount is not sufficiently obtained and the charge amount tends to be low.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a plastic sorting equipment capable of separating accurately with an electrostatic sorter even if foamed plastic is mixed in a plastic piece.

[0005]

According to the first aspect of the present invention, there is provided an electrostatic sorting apparatus for separating plastic pieces by using static electricity, and a plastic piece to be supplied to the electrostatic sorting apparatus. A frictional charging device for charging the frictional charging device, wherein the plastic piece is heated to a supply unit that supplies the plastic piece to the frictional charging device, and the foamed plastic piece included in the plastic piece is thermally shrunk. A heating device is provided.

According to the above construction, the foamed plastic piece is thermally shrunk to increase the bulk specific gravity, thereby preventing the foamed plastic piece from rising in the frictional charging device, and causing frictional contact like the other plastic pieces. And a sufficient charge can be applied, so that the separation accuracy does not decrease in the electrostatic sorter.

According to a second aspect of the present invention, in addition to the above configuration, the heating device is provided with a heating furnace for heating the plastic piece, and the plastic piece is detected based on a signal from a temperature detector for detecting the temperature of the plastic piece. And a heating temperature control device for controlling the heating state of.

According to the above configuration, since the heating temperature of the plastic piece can be controlled, unnecessary heating can be avoided, and the plastic piece melts and adheres to the transport device.
There is no possibility that the plastics adhere to each other and the separation accuracy by the electrostatic sorting device is reduced.

Further, in the invention according to claim 3, in the above construction, the plastic piece is heated to 150 ° C.
It is configured to heat in a range of 180 ° C. for 1 to 3 minutes.

According to the above construction, the foamed plastic piece is effectively thermally contracted without being melted by heat, and can be separated and recovered with high accuracy by the electrostatic sorting device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an embodiment of the plastic sorting equipment according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, the plastic sorting equipment includes a frictional charging device 1 for contact-charging a plastic piece and a polarity and a charge amount of the plastic piece in an electrostatic field 10 formed between the electrodes 5 and 6. The apparatus comprises an electrostatic separator 2 for separating materials, and a heating device 4 disposed between a hopper 3 for supplying plastic pieces and a charging friction device 1.

The electrostatic sorter 2 has a metal drum electrode 5 rotatably arranged around a horizontal axis below the frictional charging device 1 and a predetermined distance above and obliquely above the drum electrode 5. High voltage electrode 6 and the metal drum electrode 5
And a brush 7 for scraping off the plastic pieces adhered to the outer peripheral surface of the drum electrode 5. The drum electrode 5 is driven to rotate around the horizontal axis at a predetermined speed in a direction indicated by an arrow around a horizontal axis by a rotary driving device (not shown). The drum electrode 5 is grounded, for example,
The anode of the high-voltage power supply 8 is grounded, and the cathode is connected to the high-voltage electrode 6, thereby forming a sorting electrostatic field 10 between the high-voltage electrode 6 and the drum electrode 5.
Then, below the drum electrode 5, a first recovery chamber 9A to a third recovery chamber 9C partitioned by a separation plate 9a are arranged,
The plastic pieces that have passed through the electrostatic field 10 can be separated and collected by type.

As shown in FIG. 2, the heating device 4 includes a belt conveyor 11 which is a conveying device in which an endless metal belt 11a is wound between sprockets.
And a heating furnace 14 in which a heating heater 13 is spirally wound around a metal tube 12 surrounding the metal tube 12a. A heating temperature control device 15 that controls heating for about 1 to 3 minutes is provided. If the heating temperature and the heating time exceed this range, the plastic pieces begin to soften and stick to each other, and if the heating temperature and the heating time are below this range, the shrinkage of the foamed plastic piece becomes insufficient. The temperature control device 15 has a power supply 16 disposed in the metal tube 12 and a switch 17 interposed in a wiring connecting the heater 13 to the metal belt 11a.
And a temperature controller 18 for controlling the heating of the plastic pieces conveyed by the heater to a predetermined temperature range.

As shown in FIG. 3, the triboelectric charging device 1 has a charging chute 22 on the upper surface of a standing cylindrical charging container 21.
Is formed, and a discharge port 24 that can be opened and closed by a shutter device 25 is formed on the bottom surface.
Then, the stirring shaft 2 arranged at the axial center position of the charging container 21
6 is rotatably provided by a stirring driving device 27, and a stirring blade 28 is attached to the stirring shaft 26. Further, the charging container 21, the stirring shaft 26, and the stirring blade 28
At least the surface is covered with the resin for friction. The resin to be rubbed is selected to be located in the middle of the charged row of the plastic pieces to be separated, and is configured so that when the plastic pieces to be separated come into contact with each other, charges of opposite polarities are applied. ing.

In the above configuration, the plastic pieces supplied from the supply hopper 3 to the heating device 4 pass through the metal tube 12 while being conveyed by the belt conveyor 11, and are heated by the heating atmosphere, thereby forming the foamed plastic pieces. It is heat shrunk to increase the bulk specific gravity, which is almost the same as that of a plastic piece other than the foam type. As a result, even if the stirring blade 28 is turned into the charging container 21 of the frictional charging device 1 and swirled, 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 floating, and The whole is sufficiently triboelectrically charged. Further, since the inner surface of the container body 21 and the surface of the stirring blade 28 are covered with the resin to be rubbed, the electric charge charged on the plastic piece does not escape.

The plastic electrode which 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 in which the induced electric charge is (+) and the amount of electric charge is larger, the more grounded the drum electrode 4 is. And the larger the amount of charge induced (−), the more the charge is attracted to the drum electrode 4, separated into the first recovery chamber 9A to the third recovery chamber 9C and dropped, and the plastic pieces are classified by type. to recover.

(Example) Here, a mixture of a plastic piece made of PVC resin and another plastic piece containing styrene foam PS (PVC resin content is 2%)
From the hopper 3 to the heating device 4, the triboelectric charging device 1, and the electrostatic separation device 2 in that order. As a result, the heating device 4
As a result, the foamed plastic piece was heated and shrunk, and the phenomenon of floating in the charging container 21 did not occur. Then, when the foamed plastic piece is not heated and shrunk, P
In contrast to the case where the VC content was 0.9%, in the case of heat shrinkage, the PVC content was 0.5% and the PVC content was reduced. Here, PVC content = weight of PVC contained in the separated plastic piece / total weight of the separated plastic piece. In addition, this PVC content = 0.5
The value is said to be able to reduce furnace corrosion and reduce the amount of dioxin generated when plastic is used as a recycled fuel.

According to the above embodiment, the frictional charging device 1
The foamed plastic piece is thermally shrunk by introducing the plastic piece before the supply into the heating device 4 and heated to increase the bulk specific gravity, thereby preventing the foamed plastic piece from floating in the frictional charging device. As in the case of other plastic pieces, the frictional resin can be brought into sufficient frictional contact with the frictional resin and a sufficient charge can be applied, so that the separation accuracy of the foamed plastic pieces in the electrostatic sorting device 2 is reduced. Nor.

FIG. 4 shows another embodiment of the heating device.
Instead of a heating furnace using an electric heater, a heating furnace 3 using hot air
1 is provided. That is, the belt conveyor 11
A single or a plurality of air nozzles 33 are arranged in a furnace wall 32 surrounding the metal belt 11a, and hot air heated by a heat exchanger 35 from a blower fan 34 is supplied to the air nozzles 33 via a flow control valve 36. Is configured.
Then, the temperature sensor 3 disposed at the exit of the heating furnace 31
A heating temperature control device 39 is provided for operating the flow control valve 36 by the temperature controller 38 based on the detected value of 7 and controlling the heating state of the plastic piece. Of course, the hot air is blown so that the foamed plastic pieces are not blown off.

[0021]

As described above, according to the first aspect of the present invention, the foamed plastic piece is heated and contracted by heat to increase the bulk specific gravity, so that the foamed plastic piece is lifted up in the frictional charging device. As a result, frictional contact can be made in the same manner as other plastic pieces, and electric charges can be uniformly applied. Therefore, the separation accuracy of the foamed plastic pieces in the electrostatic separator does not decrease.

According to the second aspect of the present invention, since the heating temperature of the plastic pieces can be controlled, unnecessary heating can be avoided, and the plastic pieces can be melted and adhered to the transfer device, or the plastic pieces can be bonded together. As a result, the accuracy of separation by the electrostatic sorting device does not decrease.

Further, according to the third aspect of the present invention, the foamed plastic pieces are effectively thermally contracted without being thermally melted, so that the electrostatic separation device can perform accurate electrostatic separation.

[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 device 9A-9C 1st-3rd collection room 10 Electrostatic field 11 Belt conveyor 14 Heating furnace 21 Charging container 26 Stirring shaft 28 Stirring Wing

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D054 GA01 GA10 GB01 GB08 GB09 4F301 AA15 AA17 AC11 AD02 AD04 BA02 BA21 BE08 BF08 BF31

Claims (3)

[Claims] 1. A plastic sorting apparatus comprising: an electrostatic sorting device for separating plastic pieces by using static electricity; and a friction charging device for frictionally charging a plastic piece to be supplied to the electrostatic sorting device by contacting the same. And a supply unit for supplying the plastic piece to the frictional charging device, wherein a heating device for heating the plastic piece and thermally shrinking the foamed plastic piece included in the plastic piece is provided. 2. A heating apparatus, comprising: a heating furnace for heating a plastic piece; and a heating temperature control apparatus for controlling a heating state of the plastic piece based on a signal from a temperature detector for detecting a temperature of the plastic piece. The plastic sorting equipment according to claim 1, wherein: 3. A heating device is used to remove 150 plastic pieces.
The plastic sorting equipment according to claim 1 or 2, wherein heating is performed in a range of 1 to 180 ° C for 1 to 3 minutes.