JP2011131154A - Sorting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase accuracy in sorting by electrostatic charge amount with regard to a sorting device that performs sorting by the electrostatic charge amount. <P>SOLUTION: A conductive trough 120 is formed by a conductor. An electrode opposition section 122 is opposed to an electrode 140 striding an electric field space. A granule loading section 121 loads an electrified granule 701. A vibrator 130 loads the conductive trough 120 and drops the granule 701 loaded on the granule loading section 121 into the electrified field space. The electric field generator 150 generates direct voltage and applies the generated direct voltage between the electrode 140 and conductive trough 120, thereby generating electric field in the electrified field space. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sorting apparatus that sorts granular materials such as plastics based on the amount of charge.

When recycling plastic, it is necessary to divide it into different types of plastic. Methods for sorting plastic include sorting by specific gravity and sorting by charge amount.
Sorting by the amount of charge is a method of sorting by discriminating the type of plastic by static electricity generated when the plastics are rubbed together. For example, a granular material such as a plastic piece is dropped in an electric field and is selected depending on whether it is drawn to the plus electrode or the minus electrode.

JP 2005-138030 A

The Coulomb force that the granular body receives from the electric field increases as the charged amount of the granular body increases. Further, as the time during which the granular material is subjected to the Coulomb force is longer, the difference in the charge amount is reflected in the speed of the granular material, so that the accuracy of sorting by the charge amount is increased.
The present invention has been made, for example, in order to solve the above-described problems, and it is an object of the present invention to improve the accuracy of sorting based on the charge amount.

The sorting device according to the present invention includes an electrode, a conductive trough, a vibration device, and an electric field generator,
The conductive trough has an electrode facing portion facing the electrode across a predetermined electric field space, and a loading portion on which a charged granular material is placed, and is formed of a conductor.
The vibration device vibrates the conductive trough to drop the granular material placed on the above-described grain portion into the electric field space,
The electric field generator generates a DC voltage, applies the generated DC voltage between the electrode and the conductive trough, and generates an electric field in the electric field space.

  According to the sorting device according to the present invention, since the upper end of the electric field space is the start position of the dropping of the granular material, the time for the granular material to receive the Coulomb force from the electric field generated in the electric field space is increased, and the sorting by the charge amount is performed. Increases accuracy.

FIG. 2 is a system configuration diagram illustrating an example of the overall configuration of the sorting apparatus 100 according to the first embodiment. FIG. 3 is a side sectional view showing an example of the configuration of the sorting apparatus 100 according to the first embodiment. Side surface sectional drawing which shows an example of a structure of the selection apparatus in a comparative example. The figure which shows an example of the relationship between the fall start position of the granular material 701 in Embodiment 1, and a fall point. The block diagram which shows an example of a structure of the plastic electrostatic sorting apparatus in Embodiment 2. FIG. The figure which shows the result of the experiment which measured the charge amount fall by conveyance. Side surface sectional drawing which shows an example of a structure of the selection apparatus 100 in Embodiment 3. FIG. FIG. 10 is a diagram illustrating an example of a dropping point of a granular material 701 according to Embodiment 3. The block diagram which shows an example of a structure of the plastic electrostatic sorting apparatus in Embodiment 4. FIG. Side surface sectional drawing which shows an example of a structure of the selection apparatus 100 in Embodiment 5. FIG. Side surface sectional drawing which shows another example of a structure of the selection apparatus 100 in Embodiment 5. FIG.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIGS.

FIG. 1 is a system configuration diagram showing an example of the overall configuration of the sorting apparatus 100 according to this embodiment.
The sorting apparatus 100 sorts the granular material 701 by static electricity. The granular material 701 is, for example, a granular material obtained by pulverizing waste plastic. The granule 701 is a mixture of different kinds of materials such as acrylonitrile-butadiene-styrene copolymer synthetic resin (hereinafter referred to as “ABS”) and polystyrene (hereinafter referred to as “PS”). The granular material 701 was obtained as a result of removing materials other than plastic such as metal such as iron and glass, polypropylene (hereinafter referred to as “PP”), and the like by sorting in a stage before the sorting apparatus 100. Is.

The sorting device 100 includes an electrostatic generation device 110, a conductive trough 120, a vibration device 130, an electrode 140, an electric field generation device 150, and recovery devices 162 to 164.
The electrostatic generator 110 is, for example, a hexagonal drum. The electrostatic generator 110 is formed of the same material as any one of materials to be selected such as ABS, or a material positioned between materials to be selected in the electrostatic charge train. The electrostatic generator 110 puts the granular body 701 inside and rotates to cause friction between the granular bodies 701 or the granular body 701 and the electrostatic generator 110 to generate static electricity. The granular material 701 is charged by the generated static electricity. Whether the charge charged in the granular body 701 is positive or negative is determined by where the material of the granular body 701 is located in the electrostatic charging column. For example, when ABS and PS are rubbed, ABS is positively charged and PS is negatively charged.
The electrostatic generator 110 discharges the granular material 701 that has been sufficiently rubbed and charged. The granular material 701 discharged from the electrostatic generator 110 falls on the particle loading part 121 of the conductive trough 120.

The conductive trough 120 is made of a conductor such as iron. The conductive trough 120 has a loading part 121 and an electrode facing part 122.
The loading part 121 has, for example, a rectangular dish shape. The loading part 121 is arranged substantially horizontally, for example. The charged granular material 701 discharged from the electrostatic generator 110 is placed on the loading part 121. The loading part 121 is provided with an enclosure so that the granular material 701 placed thereon is not spilled, except for one short side.
The electrode facing portion 122 is connected to the short side where the enclosure of the particle loading portion 121 is not provided. The electrode facing portion 122 has a shape in which the tip of the loaded particle portion 121 is bent downward. The electrode facing portion 122 is bent at, for example, a right angle with respect to the loading portion 121. The electrode facing portion 122 has, for example, a rectangular flat plate shape. The electrode facing portion 122 faces the electrode 140. The electrode facing portion 122 is located, for example, in front of the electrode 140 and is substantially parallel to the electrode 140.

The vibration device 130 vibrates the conductive trough 120. Since the granular body 701 discharged from the electrostatic generator 110 is charged, there are cases where the positively charged granular body 701 and the negatively charged granular body 701 are electrically attracted to each other. When the vibration device 130 vibrates the conductive trough 120, such pairing is eliminated, and the granular bodies 701 are separated one by one.
At the same time, the vibration device 130 gives vibration to the conductive trough 120 so as to fly the granular material 701 placed on the loading portion 121 toward the electrode facing portion 122. As a result, the granular material 701 placed on the loaded particle portion 121 moves little by little in the direction of the electrode facing portion 122, and a space formed between the electrode facing portion 122 and the electrode 140 (hereinafter “electric field space”). Fall into).

  The electrode 140 has, for example, a rectangular flat plate shape. The electrode 140 faces the electrode facing portion 122 across the electric field space. For example, the electrode 140 is located in front of the electrode facing portion 122 and is substantially parallel to the electrode facing portion 122.

The electric field generator 150 generates a direct high voltage. One of the pair of terminals that output the DC voltage generated by the electric field generator 150 is electrically connected to the conductive trough 120 by the electric wire 151, and the other is electrically connected to the electrode 140 by the electric wire 152. As a result, the DC voltage generated by the electric field generator 150 is applied between the conductive trough 120 and the electrode 140. As a result, an electric field is generated in the electric field space between the electrode facing portion 122 and the electrode 140.
Note that the direction of the DC voltage applied between the conductive trough 120 and the electrode 140 may be positive.
For safety, the conductive trough 120 is grounded. Instead of grounding the conductive trough 120, the electrode 140 may be grounded. However, since the conductive trough 120 may be touched by an operator, it is preferable to ground the conductive trough 120. In that case, it is preferable to prevent the operator from touching the electrode 140 by mistake, for example, by covering it with an insulating sheet.

  The granular material 701 falling in the electric field space is divided into one that is pulled toward the electrode 140, one that is pulled toward the electrode facing portion 122, and one that is not pulled by either, depending on the amount of charge.

The collection devices 162 to 164 are located below the electric field space. The collection devices 162 to 164 receive and collect the granular material 701 that has fallen in the electric field space. The collection devices 162 to 164 are arranged in substantially the same direction as the direction of the electric field in the electric field space. For example, the collection device 162, the collection device 163, and the collection device 164 are arranged in this order from the side closer to the electrode facing portion 122. Thereby, the recovery unit 164 recovers the granular material 701 pulled toward the electrode 140. The collection device 164 discharges the collected granular material 704. Conversely, the granular material 701 pulled toward the electrode facing portion 122 is recovered by the recovery device 162. The collection device 162 discharges the collected granular material 702. The granular material 701 that has not been pulled by either is collected by the collection device 163. The collection device 163 discharges the collected granular material 703.
The collection device 162 to 164 in which the granular body 701 is collected is determined by the charge amount, and the charged amount of the granular body 701 is determined by the material of the granular body 701. Thereby, the granular material 701 can be sorted by material. For example, the collection device 162 collects 99% or more of ABS granular material 702. The recovery device 164 recovers the granular material 704 of 99% or more PS. The collection device 163 collects the granular material 703 from which ABS and PS are not so much selected. The collection device 163 is provided to increase the purity of the granular material 702 and the granular material 704 collected by the collection device 162 and the collection device 164.

例えば、電場発生装置１５０が生成する直流電圧Ｖが６０キロボルト［ｋＶ］、電極対面部１２２と電極１４０との間隔ｄが２０センチメートル［ｃｍ］である場合、電場空間内の電場Ｅは、３００キロボルト毎メートル［ｋＶ／ｍ］である。 FIG. 2 is a side sectional view showing an example of the configuration of the sorting apparatus 100 according to this embodiment.
For example, it is assumed that the size of the electrode facing portion 122 and the size of the electrode 140 are substantially the same, and the electrode facing portion 122 and the electrode 140 face each other in parallel and form a substantially vertical plane. A substantially horizontal electric field E is generated in the electric field space between the electrode facing portion 122 and the electrode 140. Although an electric field is generated in other spaces, it is much smaller than the electric field E in the electric field space.
When the distance between the electrode facing portion 122 and the electrode 140 is d and the DC voltage generated by the electric field generator 150 is V, the electric field E is expressed by the following equation.

For example, when the DC voltage V generated by the electric field generator 150 is 60 kilovolts [kV] and the distance d between the electrode facing portion 122 and the electrode 140 is 20 centimeters [cm], the electric field E in the electric field space is 300 It is kilovolt per meter [kV / m].

The height of the electric field space (that is, the electrode facing portion 122 and the electrode 140) is h ₁ , and the height from the lower end of the electric field space to the recovery devices 162 to 164 is h ₂ . The locus will be described. The mass of the granular material 701 is m, the charge amount is q, and the gravitational acceleration is g. The granular material 701 starts dropping when the time t is 0, reaches the lower end of the electric field space when the time t is t ₁ , and reaches the recovery devices 162 to 164 when the time t is t ₂ And

The force acting on the granular material 701 includes gravity and Coulomb force (electric force) due to the electric field E. Gravity acts in a direction perpendicular to the granular material 701. Assuming that the direction of the electric field E is horizontal, the Coulomb force acts on the granular material 701 in the horizontal direction. Therefore, the vertical direction and the horizontal direction are considered separately.
The position at which the granular material 701 starts dropping is taken as a reference, and the dropped distance is taken as x. Vertical velocity of the granules 701 (the downward direction is positive.) Expressed as a v _x, represents (as with speed to. The downward direction is positive) vertical acceleration of the granules 701 with a _x.

だから、

So,

だから、

である。

So,

It is.

だから、

The horizontal movement distance is set to y with reference to the position where the granular body 701 starts dropping. The horizontal velocity of the granular material 701 is represented by v _y and the acceleration is represented by a _y .
The Coulomb force works only while the granular material 701 is in the electric field space. Granules 701, during the time t 0 to _{t 1,} it is in an electric field space. When time t is 0 or more and t ₁ or less,

So,

だから、

When the time t is greater than _{t 1,}

So,

Therefore, the horizontal position y (t ₂ ) when the granular material 701 reaches the recovery devices 162 to 164 is

FIG. 3 is a cross-sectional side view showing an example of the configuration of the sorting apparatus in the comparative example.
The insulating trough 120 ′ is made of an insulating material. The insulating trough 120 ′ does not have the electrode facing portion 122. Instead, an electrode 140 ′ is provided separately from the insulating trough 120 ′. The electric field space is formed between the electrode 140 and the electrode 140 ′.
Since the insulating trough 120 'vibrates, it is necessary to provide an interval so as not to contact the electrode 140'. Therefore, the drop start position of the granular material 701 is above the electric field space. The height between the upper end of the drop starting position and field space of granulate 701 and h _3. The height h ₃ is, e.g., a few centimeters.
In the comparative example, it is assumed that the granular material 701 starts dropping when the time t is −t ₃ and has dropped to the upper end of the electric field space when the time t is 0.

だから、

So,

だから、

So,

Therefore, the position y (t ₂ ) when the granular material 701 reaches the recovery devices 162 to 164 is

FIG. 4 is a diagram showing an example of the relationship between the drop start position and the drop point of the granular material 701 in this embodiment.
Since y (t ₂ ) is proportional to the charge amount q, the drop point of the granular material 701 changes depending on the charge amount q. Using this, the granular material 701 is sorted by the amount of charge.
When the upper end of the electric field space is the fall start position 721, the fall point spreads greatly. Therefore, it is difficult to be influenced by disturbance factors and can be selected with high accuracy.
On the other hand, when the fall start position 721 is higher than the electric field space by h ₃ , the spread of the fall point is reduced. Therefore, the collection amount of the granular material 702 collected by the collection device 162 and the granular material 704 collected by the collection device 164 is reduced, and the accuracy of sorting is reduced.
That is, it is desirable that the drop start position 721 of the granular material 701 coincides with the upper end of the electric field space (that is, h ₃ = 0). As described above, in the configuration of the comparative example, since it is necessary to provide a gap between the insulating trough 120 ′ and the electrode 140 ′, the drop start position 721 of the granular body 701 cannot be made coincident with the upper end of the electric field space. .

  In the sorting apparatus 100 in this embodiment, since the upper end of the electric field space is the drop start position of the granular material 701, the horizontal movement distance until the granular body 701 reaches the collection devices 162 to 164 is increased, and the sorting by the charge amount is performed. Increases accuracy.

The sorting device 100 in this embodiment includes an electrode 140, a conductive trough 120, a vibration device 130, and an electric field generator 150.
The conductive trough 120 has an electrode facing portion 122 that faces the electrode 140 across a predetermined electric field space, and a loading portion 121 on which the charged granular material 701 is placed, and is formed of a conductor.
The vibration device 130 vibrates the conductive trough 120 to drop the granular material placed on the above-described grain portion into the electric field space,
The electric field generator 150 generates a DC voltage, applies the generated DC voltage between the electrode 140 and the conductive trough 120, and generates an electric field E in the electric field space.

  Thereby, the upper end of the electric field space becomes the drop start position of the granular material 701, and the horizontal movement distance until the granular material 701 reaches the recovery devices 162 to 164 is increased, so that the accuracy of sorting by the charge amount is increased.

The conductive trough 120 has a shape in which the tip of a long plate is bent.
The electrode facing portion 122 is a bent portion at the tip of the conductive trough 120.

  Thereby, the cost of manufacturing the conductive trough 120 can be kept low.

The sorting device 100 in this embodiment further includes an electrostatic generator 110 and a plurality of collecting devices 162 to 164.
The electrostatic generator 110 generates static electricity and charges the granular material 701 with the generated static electricity.
The conductive trough 120 carries the granular material 701 charged by the electrostatic generator 110.
The plurality of collection devices 162 to 164 are located below the electric field space, are aligned in the direction of the electric field E generated in the electric field space, and collect the granular material 701 dropped in the electric field space.

  Thereby, since the Coulomb force acts on the granular material 701 falling in the electric field space, the granular material 701 can be selected based on the charge amount of the granular material 701.

  The electrode facing part 122 may be integrated with the particle loading part 121 or may be a part in which another part is fixed to the particle loading part 121. For example, the entire conductive trough 120 may be formed of a single plate, and the tip thereof may be bent to form the electrode facing portion 122. Alternatively, the electrode facing portion 122 may be formed as a component different from the loading portion 121 and fixed to the loading portion 121 by welding or screws (two-piece coupling structure). In that case, the particle loading part 121 and the electrode facing part 122 do not necessarily need to be made of the same material, and both are made of a conductor such as a metal and may be electrically connected.

  Moreover, it is good also as a structure which provides a plate-shaped or mesh-shaped shield above the front-end | tip vicinity of the loading part 121.

  In addition, since the conductive trough 120 is formed of a conductor, while the granule 701 is placed on the loading part 121, the electric charges charged in the granule 701 are discharged, and the granule in the electric field space is discharged. There is a concern that the force 701 receives from the electric field E is weakened. However, it has been found by experiments that the amount of discharge while the granular material 701 is placed on the loading part 121 is very small. Therefore, the force that the granular body 701 receives from the electric field E in the electric field space does not become weak and does not affect the accuracy of sorting.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIGS.

  FIG. 5 is a block diagram showing an example of the configuration of the plastic electrostatic sorting device in this embodiment.

  In the triboelectric charging device 1 (electrostatic generator 110), a mixture of a plurality of types of crushed plastic pieces (granular bodies 701) as granular bodies is put into a charging cylinder and rotated and agitated. The plastic piece is charged according to the charge train.

The vibration trough 2b (conductive trough 120) is a conveying device disposed below the bottom outlet of the friction charging device 1, and is made of a metal conductor. The vibration trough 2b conveys the plastic piece in the direction of arrow A while leveling the plastic piece by the vibration applied by the excitation unit 2a (vibration device 130). The vibration trough 2b allows the plastic piece to fall freely from the drop part 3 formed at the tip part.
The vibration trough 2b is made of a metal conductor. The tip of the vibration trough 2b is bent vertically downward to form a bending guide 2c (metal conductor) (electrode facing portion 122). The length of the bending guide 2c is about the same as the counter electrode 4b (electrode 140). The bending guide 2c also serves as the first ground electrode.

  The vibration trough 2b conveys a plurality of types of granular materials while leveling them in the direction of the dropping portion 3. The vibration trough 2b is made of a metal conductor. The vibration trough 2b is a ground electrode that also serves as the first electrode. The counter electrode 4b is a positive second electrode that is a counter high voltage electrode that faces the ground electrode at a predetermined interval. The dropping part 3 is sandwiched between the ground electrode and the counter electrode 4b. The ground electrode and the positive counter electrode 4b constitute a counter electrode high voltage electrode. The counter electrode high voltage electrode is electrically connected to a DC high voltage power source 5 for applying a high voltage. Below the gap 6 between the electrodes, a first collection box container 7a (collection device 162), which is a collection box for collecting positively charged sorting material, and a first collection box for collecting negatively charged sorting material. Two recovery box containers 7b (recovery device 164) are disposed.

  The plastic piece charged by the frictional charging device 1 falls on the vibration trough 2b, and the plastic piece advances while being leveled in the direction indicated by the arrow A by the vibration of the vibration trough 2b. The plastic piece dropped vertically downward at the dropping portion 3 at the tip of the vibration trough 2b enters the electric field formed by the ground electrode and the positive counter electrode 4b at a stage where the falling speed is low immediately after the start of dropping, and is electrostatically charged. Receive power. The positively charged plastic piece is attracted to the ground electrode side which is the negative electrode portion. The negatively charged plastic piece is attracted to the counter electrode 4b side which is a positive electrode portion. As a result, the positively charged plastic piece can be reliably collected in the first collection box container 7a, and the negatively charged plastic can be reliably collected in the second collection box container 7b.

  Thus, since the vibration trough 2b and the bending guide 2c are made of a metal conductor, the electric lines of force emitted from the second electrode terminate in the vibration trough 2b and the bending guide 2c. Thereby, the range of the electric field region extends to the vibration trough 2b. Therefore, since the plastic piece charged by the frictional charging device 1 can enter the electric field from the stage where the initial speed is low in the vertical direction, it can receive the electrostatic force for a long time, and there is no misselection with high accuracy. Can be sorted.

  If the conveyance path is made of a metal such as iron, there is a concern that the charge held by the plastic piece charged in the frictional charging device 1 flows through the conveyance path and the charge of the plastic piece decreases. However, if the decrease in the charge amount is negligibly small, there is no practical problem.

FIG. 6 is a diagram illustrating a result of an experiment in which a decrease in charge amount due to conveyance is measured.
The experiment was performed as follows. First, the charge amount of the charged plastic piece is measured (first time). After the plastic piece flows on the stainless steel vibration trough 2b, the second charge amount is measured. Furthermore, after flowing on the vibration trough 2b made of stainless steel, the third charge amount is measured. The vibration trough 2b used in the experiment has a width of 1000 mm and a length of 800 mm. The time required for the plastic piece to pass over the vibration trough 2b is several seconds.
In this way, in the case of a trough structure in which the length advances about 800 mm over several seconds, there is no practical problem even if the trough material is a metal instead of an insulator.

  The counter electrode 4b may be a plus electrode or a minus electrode with respect to the ground electrode. In either case, sorting is possible.

  The plastic electrostatic sorting device (sorting device 100) described above separates the granular material with electrostatic force according to the charged positive and negative charge amounts. The vibration trough (conducting trough 120) has a dropping portion formed at the tip, conveys the plurality of types of granular materials 701 in the direction of the dropping portion, is made of a metal conductor, and has a bending guide. The vibration trough is grounded with the role of the first electrode. The second electrode (counter electrode, electrode 140) is charged positively or negatively with respect to the potential of the first electrode.

  In this way, the drop electrode 3 is formed at the tip, and the vibration trough made of the metal conductor that transports the granular material 701 while smoothing the granular material 701 in the direction of the drop, without placing the drop distance, In this configuration, the electrodes are opposed to each other so that they can enter the electric field from the stage where the falling speed is low, thereby eliminating misselection even when the frictional charge of granular materials such as crushed plastic pieces is small. Therefore, it can be accurately and reliably selected.

Since the vibration trough is formed of a metal conductor, the strength is high and fatigue failure due to vibration can be prevented.
Even if the vibration trough is formed of a metal conductor, the discharge of the granular material 701 is negligible.
Since the bending guide is the first electrode and is integrated with the vibration trough, it is not necessary to separate the distance so that the vibration trough and the first electrode do not contact each other, and the plastic piece can enter the electric field from the stage where the initial velocity is low. it can.

Embodiment 3 FIG.
The third embodiment will be described with reference to FIGS.
Note that portions common to Embodiment 1 or Embodiment 2 are denoted by the same reference numerals and description thereof is omitted.

FIG. 7 is a cross-sectional side view showing an example of the configuration of the sorting apparatus 100 in this embodiment.
The sorting device 100 further includes an auxiliary electrode 145 in addition to the configuration described in the first embodiment.

The electrode facing portion 122 is smaller than the electrode 140. The height h ₁₁ of the electrode facing portion 122 is lower than the height h ₁ of the electrode 140. The electrode facing portion 122 faces the electrode 140 across the electric field space.
The auxiliary electrode 145 is located below the loading part 121. The auxiliary electrode 145 is electrically connected to the conductive trough 120 by an electric wire 153. Therefore, the potential of the auxiliary electrode 145 is equal to the potential of the conductive trough 120. The auxiliary electrode 145 is located farther from the electrode 140 than the electrode facing portion 122, and faces the electrode 140 across the electric field space. A distance d ₂ between the auxiliary electrode 145 and the electrode 140 is larger than a distance d ₁ between the electrode facing portion 122 and the electrode 140. For example, the distance d ₁ between the electrode facing portion 122 and the electrode 140 is 20 centimeters [cm], and the distance d ₂ between the auxiliary electrode 145 and the electrode 140 is 40 centimeters [cm], which is twice that distance. . In that case, the electric field E ₂ in the electric field space between the auxiliary electrode 145 and the electrode 140 is half of the electric field E ₁ in the electric field space between the electrode facing portion 122 and the electrode 140.

  As shown in FIG. 4, the charge charged in the granular material 701 is repulsive to the electrode 140 (a positive charge when the potential of the electrode 140 is higher than the potential of the electrode facing portion 122. On the contrary, the potential of the electrode 140 is When the potential is lower than the potential of the facing portion 122, the granular body 701 falls to the left side (the direction far from the electrode 140) from the drop start position.

  The sorting apparatus 100 shortens the electrode facing portion 122 and, instead, provides the auxiliary electrode 145 at a position farther from the electrode 140 than the electrode facing portion 122. As a result, the granular material 701 charged with the electric charge repelling the electrode 140 is prevented from hitting the electrode facing portion 122 during dropping, so that the accuracy of sorting is increased.

The position y (t ₂ ) when the granular material 701 reaches the recovery devices 162 to 164 is represented by the following equation.

FIG. 8 is a diagram showing an example of a drop point of the granular material 701 in this embodiment.
Thick line represents the case where the electric field E ₂ is half of the electric field E _1. Thin line represents the case where the electric field _{E 2} is equal to the electric field _{E 1.}
Thus, even in half the electric field E ₂ is the electric field E _1, falling point of the granules 701 is less affected. Since the dropping speed of the granular body 701 gradually increases, it takes time for the granular body 701 to fall between the electrode facing portion 122 and the electrode 140 in the electric field space, whereas the granular body 701 assists. It takes less time to drop between the electrode 145 and the electrode 140. Thus, the influence of an electric field _{E 2} is relatively small.

The sorting apparatus 100 in this embodiment further includes an auxiliary electrode 145.
The auxiliary electrode 145, together with the electrode facing portion 122 of the conductive trough 120, faces the electrode 140 across the electric field space and is electrically connected to the conductive trough 120.

  Since the length of the electrode facing portion 122 can be shortened, it is possible to prevent the granular body 701 charged to a polarity repelling the electrode 140 from hitting the electrode facing portion 122 during the fall and to increase the accuracy of selection. .

The electrode facing portion 122 is located between the electrode 140 and the auxiliary electrode 145.
Since the auxiliary electrode 145 is located farther from the electrode 140 than the electrode facing portion 122, the charged particles repelling the electrode 140 are prevented from hitting the auxiliary electrode 145 during the fall, and the sorting accuracy is increased. be able to.

  Note that the auxiliary electrode 145 may not be electrically connected to the conductive trough 120 and a voltage having a polarity opposite to that of the electrode 140 may be applied to the auxiliary electrode 145.

Embodiment 4 FIG.
The fourth embodiment will be described with reference to FIG.

  FIG. 9 is a configuration diagram showing an example of the configuration of the plastic electrostatic sorting device in this embodiment.

  The vibration trough 2b (conductive trough 120) is a transport device disposed below the bottom outlet of the friction charging device 1 (electrostatic generator 110). The vibration trough 2b conveys the plastic piece (granular body 701) in the direction of the arrow A while leveling by vibration, and freely drops the plastic piece from the dropping portion 3 formed at the tip. The vibration trough 2b is made of a metal conductor. The tip of the vibration trough 2b is bent vertically downward to form a bending guide 2c (metal conductor) (electrode facing portion 122). The lower end of the bending guide 2c is below a virtual line connecting the uppermost surface of the first electrode (earth electrode 4a) (auxiliary electrode 145) and the uppermost surface of the second electrode (counter electrode 4b) (electrode 140). The structure extends to the side. In other words, the bending guide 2c has a structure in which it enters the electric field region. Other configurations are the same as those of the second embodiment.

  Thus, as in the second embodiment, the plastic piece can enter the electric field in the vertical direction from the stage where the initial velocity of the plastic piece is low. Can be sorted.

  The plastic electrostatic sorting apparatus (sorting apparatus 100) described above is charged by dropping a plurality of charged granular materials between two electrodes that are arranged opposite to each other and to which an electric field is applied. The particles are separated by electrostatic force according to the positive and negative charge amounts. The vibration trough 2b has a drop part 3 formed at the tip, conveys the plurality of types of granular materials while being uniform in the direction of the drop part, is made of a metal conductor, and has a bending guide 2c. The first electrode is arranged to extend in the dropping direction from immediately below the dropping portion 3 of the vibration trough 2b. The second electrode is disposed opposite to the first electrode from the front part of the drop part 3 of the vibration trough 2b, and is charged positively or negatively with respect to the potential of the first electrode. The bending guide 2c is configured by bending the tip of the vibration trough 2b forming the dropping portion 3 in the vertically downward direction, and is exposed to an electric field created between the pair of electrodes.

  In this way, the drop electrode 3 is formed at the tip, and the vibration trough made of the metal conductor that transports the granular material 701 while smoothing the granular material 701 in the direction of the drop, without placing the drop distance, In this configuration, the electrodes are opposed to each other so that they can enter the electric field from the stage where the falling speed is low, thereby eliminating misselection even when the frictional charge of granular materials such as crushed plastic pieces is small. Therefore, it can be accurately and reliably selected.

Embodiment 5 FIG.
The fifth embodiment will be described with reference to FIGS.
Note that portions common to any of Embodiments 1 to 4 are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, a modified example of the conductive trough 120 will be described.

FIG. 10 is a cross-sectional side view showing an example of the configuration of the sorting apparatus 100 in this embodiment.
In this example, the electrode facing portion 122 has a shape that is bent at an acute angle with respect to the loaded portion 121. The electrode facing portion 122 is not vertical but is inclined in an overhang shape, and is separated from the electrode 140 as it goes downward.
As a result, as in the second embodiment, it is possible to prevent the granular body 701 charged with the electric charge repelling the electrode 140 from hitting the electrode facing portion 122 during dropping, and to increase the accuracy of selection.

  Similarly, the electrode 140 may be arranged not to be vertical but to be inclined in an overhang shape and away from the electrode facing portion 122 as it goes downward. By doing so, it is possible to prevent the granular body 701 charged with the electric charge attracted to the electrode 140 from hitting the electrode 140 during the fall and to increase the accuracy of selection.

FIG. 11 is a cross-sectional side view showing another example of the configuration of the sorting apparatus 100 in this embodiment.
In this example, the electrode facing portion 122 is not at the tip of the particle loading portion 121 but at a position farther from the electrode 140 than the tip.
As a result, as in the above example, it is possible to prevent the granular body 701 charged with the electric charge repelling the electrode 140 from hitting the electrode facing portion 122 during dropping, and to increase the accuracy of selection.

  In addition, about the part close | similar to the electrode 140 rather than the electrode facing part 122 among the particle mounting parts 121, you may form with insulators, such as a plastic instead of a conductor.

  DESCRIPTION OF SYMBOLS 1 Friction charging device, 2a Exciting part, 2b Vibrating trough, 2c Bending guide, 3 Dropping part, 4a Ground electrode, 4b Counter electrode, 5 High voltage power supply, 6 Gap part, 7a, 7b Collection box container, 100 Sorting apparatus, 110 Electrostatic generator, 120 conductive trough, 121 loading part, 122 electrode facing part, 130 vibration device, 140 electrode, 145 auxiliary electrode, 150 electric field generator, 151, 152, 153 electric wire, 162-164 recovery device, 701 704 Granule, 721 Fall start position.

Claims (5)

An electrode, a conductive trough, a vibration device, and an electric field generator,
The conductive trough has an electrode facing portion facing the electrode across a predetermined electric field space, and a loading portion on which a charged granular material is placed, and is formed of a conductor.
The vibration device vibrates the conductive trough to drop the granular material placed on the above-described grain portion into the electric field space,
The electric field generator generates a DC voltage, applies the generated DC voltage between the electrode and the conductive trough, and generates an electric field in the electric field space. The sorting device further includes an auxiliary electrode,
2. The sorting apparatus according to claim 1, wherein the auxiliary electrode faces the electrode across the electric field space together with the electrode facing portion of the conductive trough, and is electrically connected to the conductive trough.   The sorting apparatus according to claim 2, wherein the electrode facing portion is located between the electrode and the auxiliary electrode. The conductive trough is a shape in which the tip of a long plate is bent,
4. The sorting apparatus according to claim 1, wherein the electrode facing portion is a bent portion of a tip of the conductive trough. The sorting device further includes an electrostatic generation device and a plurality of recovery devices,
The electrostatic generation device generates static electricity, and the granular material is charged by the generated static electricity,
The conductive trough is mounted with a granular material charged by the electrostatic generator,
The plurality of recovery devices are located below the electric field space, are arranged side by side in the direction of the electric field generated in the electric field space, and collect particulate matter that has fallen in the electric field space. The sorting apparatus according to any one of claims 1 to 4.

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