JP3370512B2 - Plastic sorting method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic sorting method and device for sorting plastic pieces by type using a charging train.

[0002]

2. Description of the Related Art In recent years, garbage recycling has been promoted. Plastics consumed as raw materials for plastic products include vinyl chloride resin (hereinafter abbreviated as PVC),
Polyethylene resin (hereinafter abbreviated as PE), polypropylene resin (hereinafter abbreviated as PP), polystyrene resin (hereinafter abbreviated as PS), and methacrylic resin [acrylic resin] (hereinafter abbreviated as PMMA) It is considered that 80% of the waste plastics are recovered and most of the waste plastics are recovered. Polyethylene terephthalate resin (hereinafter abbreviated as PET), which is often used as a PET bottle, is also being independently collected. When recycling these resins, it is important to separate them by type of resin, but the separation technology has not been established.

By the way, there is, for example, an electrostatic separator as a device for selecting crushed dust. As shown in FIG. 6, this electrostatic sorter includes a drum electrode 41 that is rotatably disposed and grounded, and a counter that is disposed so as to face the drum electrode 41 and to which a high voltage is applied by a power supply device 43. An electrostatic field R formed by the drum electrode 41 and the counter electrode 42 by providing an object to be sorted on a rotating drum electrode 41.
The insulator that is strongly charged and strongly attracted to the drum electrode 41 side is separated into the first tray 44A, and the conductor that is not charged and repelled by the drum electrode 41 is passed through the third tray 4A.
4C, and the intermediate semiconductor is separated into the second tray 44B.

[0004]

SUMMARY OF THE INVENTION In the above electrostatic separator,
Since plastic is an insulator, all plastic pieces are sucked by the drum electrode 41 and discharged to the first tray 44A.

By the way, the plastic which is an insulator is
There is a charging column in which ones that are easily charged positively (plus) to ones that are easily charged negatively (negative) are arranged in a line depending on the material. It is possible to separate plastic pieces by material with the above electrostatic sorter, but the electrostatic field R
The difference in the amount of electric charge (pressure) charged in is small, and it is difficult to sort the plastics by type with a conventional electrostatic sorting device.

By the way, as shown in FIG. 7, the conditions for dropping charged objects P to be separated between the electrode plates are represented by the following equations. k × (q ₁ · q ₂ ) / r ² > mg where k: proportional constant 8.99 × 10 ⁹ N · m ² · C
^-3 q ₁ : charge of the plastic piece q ₂ : charge on the surface of the electrode plate r: distance between q ₁ and q ₂ (≈ distance between the plastic piece and the electrode plate) m: weight of the plastic piece g: gravitational acceleration If not satisfied, the sorting accuracy will be poor. Therefore, it is necessary to increase the applied voltage applied between the electrode plates, and further increase the voltage in order to increase the processing amount.

According to the present invention, a plastic piece rubbed by a material to be rubbed located in the middle portion of the charging train is charged with a positive charge at a charging position on the positive side of the position of the rubbed material in the charging train. On the other hand, pay attention to the point that the negative charge is charged on the negative side of the friction material position, and that the attraction force or repulsive force is generated due to the difference in charge by passing the electrostatic field. It was done by.

It is an object of the present invention to provide a method and an apparatus for selecting plastic pieces, which can sort plastic pieces by type with a voltage lower than conventional ones.

[0009]

In order to achieve the above object, the method for selecting plastics according to claim 1 of the present invention comprises:
Wood plastic pieces consisting of ground plural kinds of materials
A method of sorting plastics by quality , in which a plastic material located in the middle position of the electrified row of plastics
A reference plastic material is formed by tics, and the plastic piece is brought into frictional contact with the reference plastic material. In addition to being charged, a negative charge is applied to the plastic piece at the charging position where it is more likely to be charged to the negative side of the reference plastic material in the charging row, and then the plastic piece is separated from the moving electrode and the counter electrode by a static separator. Separate each piece of plastic by passing it through an electric field.
To the moving electrode and the counter electrode.
Suction repulsive force according to the electric charge of each plastic piece
It is used and separated . The plastic sorting device according to claim 2 is a plastic sorting device that sorts plastic pieces made of a plurality of crushed materials by material, and the plastic sorting device is arranged upstream of the sorting path. During transport, the middle part of the charge train of the plastic pieces
By frictional contact with the reference plastic material made of a material of the plastic located in location, together with the charges the positive charge on the plastic pieces of the charging easily charging position to the plus side of the reference plastic material in the triboelectric series than the reference plastic material Charging means for charging a negative charge to a plastic piece at a charging position where it is easy to be charged to the negative side, and further passing each electrostatic field for separation placed downstream of this charging means to further charge each plastic piece.
And to each of the moving electrode and the counter electrode
Utilizing the suction repulsion force according to the electric charge of the plastic piece
Comprising a separating means for separating Te, said separating means includes a moving electrode to convey drop plastic chips are transported fall
A counter electrode facing the moving electrode with a plastic piece sandwiched therebetween, and a power supply device for applying a high voltage to the moving electrode and the counter electrode to form a separating electrostatic field between the moving electrode and the counter electrode. is there.

According to a third aspect of the present invention, there is provided a plastic sorting apparatus in which the counter electrode having the above structure is rotated about a horizontal axis.
The counter drum electrode is rotated.

According to the sorting method and apparatus of the above-mentioned claims 1 and 2, the friction with the reference plastic material causes
Corresponding to the rank of the electrification row for the standard plastic material,
Different polarities and amounts of charge are applied to each plastic piece, and due to the difference in the polarity and the amount of charge (voltage) of this charge, multiple materials contained in the plastic piece can be It is possible to select at least three or more of the one having the opposite polarity and being sucked, the one having the same polarity and being repelled, and the middle thereof. It is possible to sort accurately according to each material. Further, since the plastic piece is frictionally charged before being charged into the separation charging field, the voltage applied to the electrode is lower than that in the conventional case, and the separation can be performed accurately.

According to the sorting apparatus of the third aspect, the plastic pieces adsorbed on the counter electrode can be easily collected by the scraping tool.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Here, an embodiment of a plastic sorting apparatus according to the present invention will be described with reference to FIGS.

As shown in FIG. 1, this plastic sorting apparatus has a charging means 1 arranged upstream of a sorting path.
And a separating means 2 arranged on the downstream side of the charging means 1.

In the charging means 1, as shown in FIG. 2, the inner cylindrical body 3a made of the reference plastic material in the middle of the charging sequence is fitted inside the metallic outer cylindrical body 3b through the insulating member 3c. The coated charging container 3 is disposed, and the crushed plastic pieces are fed from the storage hopper 4a to the constant quantity feeder 4
b, there is provided a plastic piece supply device 4 for introducing the plastic piece supply port 3d into the charging container 3 through the rotary valve 4c. Further, the charging container 3 is provided with a swirl sliding contact device 5 for blowing swirling sliding contact air A in a tangential direction into the charging container 3 from a blower fan 5a through an air supply pipe 5b into an upper blowing port 3e. With the swivel / sliding device 5, the plastic piece charged into the charging container 3 from the plastic piece supply port 3d is swung to frictionally contact the inner peripheral surface of the inner cylindrical body 3a to be charged, and further discharged from the discharge port 3f. It is configured to discharge.

Here, the reference plastic material will be described. Instead of the reference plastic material, it is also possible to use a metal such as copper, chromium, nickel, etc., which are located in approximately the same order as PS in the charging train. However, since the electric charge charged by friction escapes due to contact with the metal, it is better to use a plastic material that is an insulating material as the material to be rubbed. By the way, PVC, PE, PP, P
When S, PMMA, and PET are arranged in the order of the charging columns, PMMA → PS → PE → PP
→ PET → PVC (There is also another material showing PP → PVC → PET) and it is arranged on the side that is easily negatively charged.
Here, of PS, PE and PP which are located in the middle rank,
For example, when PP is selected as the reference plastic material and another plastic piece is rubbed against the PP reference plastic material, a large number of positive charges are charged in the order of PE <PS <PMMA plastic pieces, and PP plastic pieces are also charged. Is hardly charged, and more negative charges are charged in the order of PET <PVC plastic pieces. In this way, by selecting the middle rank plastic of the charging sequence as the reference plastic material, the mixed plastic pieces are charged with positive charge and negative charge for each type, and the charge amount (band Voltage) can be different.

As shown in FIG. 1, the separating means 2 is a metallic drum electrode 11 which is a moving electrode which is rotated around a horizontal axis in the direction of arrow B at a predetermined speed and is grounded.
And a counter electrode 13 in the shape of an arc plate, which is arranged in the drum electrode 11 at a constant interval in the vicinity of the exit of the guide plate 12, and a high voltage is applied to the counter electrode 13 for sorting. The power supply device 14 for forming the electrostatic field R, the first separation tray 15A arranged below the sorting electrostatic field R on the drum electrode 11 side, and the first separation tray 15A arranged below the sorting electrostatic field R on the counter electrode 13 side. The second separation tray 15B, and the scraper 16 is disposed on the outer peripheral portion of the drum electrode 11 above the outer end portion of the first separation tray 15A.

Therefore, a plastic piece having a positive charge opposite to that of the drum electrode 11 is adsorbed on the surface of the drum electrode 11 and the adsorbing surface faces downward or is separated by the scraper 16 and separated in the first separation tray 15A. Be dropped. Further, the plastic piece charged with the negative electric charge is repelled by the drum electrode 11 and sucked by the counter electrode 13, and is dropped onto the second separation tray 15B to be separated.

Here, FIG. 3 shows the results of a screening experiment using only PVC, for example, as a result of screening several kinds of plastics such as PVC, PP and PE using PP as a reference plastic by the above apparatus. According to the experimental results, the recovery rate of PVC plastic pieces was 90%, and the purity thereof was 95%.

According to the above-described embodiment, the charging means 1 makes frictional contact with the inner surface of the inner cylindrical body 3a made of the reference plastic material, and the plastic piece charged positively in accordance with the order of the charging sequence. , A plastic piece having a negative electric charge and a non-charged plastic piece are formed. When falling, the drum electrode 11 adsorbs a plastic piece charged with a positive charge and repels a plastic piece charged with a negative charge,
Further, the opposite electrode 13 to which the positive voltage is applied attracts the plastic piece charged with the negative charge. As a result, the plastic pieces charged with positive charges can be separated and collected in the first separation tray 15A, and the plastic pieces charged with negative charges and the uncharged plastic pieces can be collected in the second separation tray 15B. It is possible to separate the plastic pieces by type with high recovery rate and high purity. Further, since the plastic piece already charged by the charging means 1 is further charged by the electrostatic field for separation R, the voltage applied to the drum electrode 11 and the counter electrode 13 can be accurately separated at a voltage lower than the conventional voltage. .

Of course, the above-mentioned selection can be repeated a plurality of times, or the separation can be performed again by using a charging container having a different reference plastic material. The drum electrode may be an endless belt type moving electrode, and three or more separation trays may be installed.

FIG. 4 shows a modification of the charging container 3. That is, in the charging container 3, the shaft cylinder 21 arranged at the axial center position is provided.
And a spiral guide fin 22 is attached between the shaft cylinder 21 and the inner peripheral surface of the inner cylinder body 3a, and the shaft cylinder 21 and the guide fin 22 are formed of the same reference plastic material as the inner cylinder body 3a. A long spiral sliding contact path 23 is formed. With this spiral sliding contact path 23, the sliding contact area between the plastic piece and the reference plastic material can be greatly increased, the amount of charge can be increased, and the sorting accuracy can be improved.

FIG. 5 shows a modification of the counter electrode. That is, this counter electrode is composed of the drum-shaped counter electrodes 31 arranged in parallel to each other at a constant distance from the drum electrode 11, and is rotated by a rotating device (not shown) in the C direction facing the drum electrode 11. Has been done. Further, a scraper 32, which is a scraping tool for scraping off the adsorbed plastic pieces in sliding contact with the outer peripheral surface of the drum-shaped counter electrode 31, and a third separating tray 33 for accommodating the scraped plastic pieces are provided. .

According to the above construction, the plastic piece which is negatively charged and repelled by the drum electrode 11 is
It can be positively adsorbed and scraped off by the scraper 32, and the separation accuracy can be further improved.

[0025]

As described above, according to claims 1 and 2
According to the described invention, by friction with the reference plastic material, different polarities and charge amounts are given to the respective plastic pieces in accordance with the order of the charging series with respect to the reference plastic material,
Due to the difference between the polarity of the charged electric charge and the amount of electric charge (voltage), a plurality of materials contained in the plastic piece are attracted to the separation charge field forming electrode with the opposite polarity and the same polarity. It is possible to select at least three or more of the ones repelled by and those in the middle, and it is possible to accurately select the plastic pieces for each material in accordance with the order of the charging columns according to the material. In addition, since the plastic piece is frictionally charged before being charged into the separation charging field, the voltage applied to the electrode is lower than that in the conventional case, and the separation can be performed accurately.

According to the sorting apparatus of the third aspect, the plastic pieces adsorbed on the counter electrode can be easily collected by the scraping tool.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a plastic sorting apparatus according to the present invention.

FIG. 2 is a vertical cross-sectional view showing a charging device of the sorting apparatus.

FIG. 3 is a graph showing the relationship between the recovery state and purity of plastic pieces and the applied voltage by the sorting apparatus.

FIG. 4 is a vertical cross-sectional view showing a modified example of the charging container of the sorting apparatus.

FIG. 5 is a configuration diagram showing a modified example of a counter electrode of the sorting apparatus.

FIG. 6 is a configuration diagram showing a conventional electrostatic sorting device.

FIG. 7 is an explanatory diagram showing the principle of conventional electrostatic separation.

[Explanation of symbols]

1 charging means 2 Separation means 3 charging container 3a Inner cylinder (standard plastic material) 3b outer cylinder 3c Insulation member 3d plastic piece supply port 3e Blower 3f outlet 4 Plastic piece feeding device 5 Swivel sliding contact device 11 drum electrode 12 Guide plate 13 Counter electrode 14 power supply 15A First separation tray 15B Second separation tray 16 scrapers R separation electrostatic field 23 spiral sliding contact path 31 Drum type counter electrode 32 scrapers

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Daisuke Tamakoshi, 3-8, Nishikujo 5-chome, Konohana-ku, Osaka City, Osaka Prefecture, Japan, Hitachi Shipbuilding Co., Ltd. (56) Reference: JP-A-7-328482 (JP, A) ( 58) Fields investigated (Int.Cl. ⁷ , DB name) B03C ^7/ 00-7/12

Claims (3)

(57) [Claims] 1. A method of selecting plastics, in which plastic pieces made of a plurality of kinds of crushed materials are sorted by material, wherein the plastic pieces are located at an intermediate position of a charging row of the plastic pieces.
Forming a reference plastic material by the plastic, frictionally contact the plastic piece to the reference plastic material,
Among the plastic pieces, the plastic piece at the charging position where it is more likely to be charged to the plus side than the reference plastic material in the charging row is charged with a positive charge, and the plastic piece at the charging position where it is more likely to be charged to the minus side than the reference plastic material in the charging row. Each piece of plastic is charged with a negative electric charge, and then a piece of plastic is passed through a separating electrostatic field formed between the moving electrode and the counter electrode to separate each plastic plate.
The moving piece is further charged with further charging the plastic piece.
And the electric charge of each plastic piece against the counter electrode
A method for selecting plastics, characterized in that the plastics are separated by utilizing a corresponding suction repulsive force . 2. A plastic sorting apparatus for sorting plastic pieces made of a plurality of kinds of crushed materials by material, wherein the plastic pieces are arranged on the upstream side of a sorting path while the plastic pieces are being sent . Located in the middle position of the charge train of the plastic pieces
By frictional contact with the reference plastic material made of a material of plastic, charging a positive charge on the plastic pieces of the charging easily charging position to the plus side of the reference plastic material in the triboelectric series with charging, the negative side of the reference plastic material The charging means for charging the plastic piece at the charging position, which is easy to charge, with a negative electric charge, and the electrostatic field for separation, which is arranged on the downstream side of this charging means, to pass through, thereby further charging each plastic piece.
The moving electrodes and the counter electrodes.
Use the repulsive force of attraction according to the electric charge of the stick
Comprising a separating means for releasing the separating means, the moving electric across the moving electrode for conveying dropped plastic pieces, plastic pieces that will be transported fall
A plastic sorting device comprising: a counter electrode facing a pole ; and a power supply device for applying a high voltage to the moving electrode and the counter electrode to form a separating electrostatic field between the moving electrode and the counter electrode. . 3. The counter electrode is constituted by a counter drum electrode rotated about a horizontal axis.
The described plastic sorting device.