JP2002046128A - Apparatus and method for selectively recovering plastic pieces - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively recover a mixture containing a plurality of plastic pieces. SOLUTION: A method for selectively recovering plastic pieces to selectively recover a specific type from the mixture containing the plurality of plastic pieces comprises the steps of introducing the mixture between a heating member having a heating surface held at a temperature suitable to selectively recover the specific type of the pieces and a contact member provided oppositely to the heating member and having a contact surface oppositely to the heating surface, further contacting the mixture with the heating surface of the heating member by the contact surface of the contact member, heating the mixture by the heating surface of the heating member, fusion bonding the specific type of the pieces in the mixture to the heating surface of the heating member to recover the pieces. An apparatus for selectively recovering the plastic pieces by using this method is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic piece selecting apparatus and a plastic piece for selectively recovering a specific type of plastic piece from a mixture of a plurality of types of plastic pieces by utilizing unsteady heat conduction and fusion phenomenon. The present invention relates to a method for selectively collecting pieces.

[0002]

BACKGROUND OF THE INVENTION Plastics are used in many industrial products today and are visually selected by imprinting the name of the plastic material on the product or part to separate the plastic when the industrial products are discarded. Methods and methods of limiting the type of plastic material used in the product have been employed. However, in the so-called shredder dust obtained by disposing a large number of industrial products, it is hardly performed to select and collect plastic pieces.

[0003]

In order to select a specific kind of plastic piece from a mixture in which a plurality of plastic pieces are mixed, a "floating and sinking method" using a different density (specific gravity) for each material is used. I have. With the flotation method, it is possible to select a plastic piece having a density significantly different from other plastic pieces, for example, a plastic piece mixed with glass fiber, but it is difficult to select a plastic piece with a small density difference It is.

[0004] Further, an "electrostatic method" has been proposed in which a plastic piece is selected by utilizing a difference in the dielectric constant of a material. However, the electrostatic method has a drawback that when the conductive material is contained in the plastic pieces, it is difficult to sort each plastic piece. In order to overcome these disadvantages, the present invention utilizes a transient heat conduction and a fusion phenomenon, and a plastic piece selective recovery apparatus for selectively recovering a specific type of plastic piece from a mixture of a plurality of types of plastic pieces. An object of the present invention is to provide a method for selectively collecting plastic pieces.

[0005]

SUMMARY OF THE INVENTION The present invention solves the problem of selectively recovering a specific type of plastic piece from a mixture of a plurality of types of plastic pieces by utilizing unsteady heat conduction and fusion phenomenon. ing. That is, the present invention provides a method for selecting and recovering a specific type of plastic piece from a mixture containing a plurality of types of plastic pieces, wherein the mixture is maintained at a temperature determined according to the specific type of plastic piece. The mixture is heated by the heating surface of the heating member, and a specific type of plastic piece in the mixture is fused to the heating surface of the heating member. And a method for selecting and collecting plastic pieces.

There are several types of plastic pieces, and the thermal and rheological properties of each of these plastic pieces are very different. The present invention
(1) When a piece of plastic at normal temperature and a heated surface at high temperature are brought into contact with each other, the unsteady heat conduction determined by physical properties of both materials, for example, density, specific heat, thermal conductivity, etc., determines the contact interface temperature between the two. Governing, and (2) the phenomenon of fusion between the heated surface and the plastic piece, the interface temperature between the heated surface and the plastic piece is determined by the fusion start temperature (part of the plastic piece The temperature at which the material begins to adhere to the heated surface when it is melted by the heated surface of the heating member, and becomes remarkable when the temperature exceeds the softening point). Became possible.

[0007] The present invention further provides a plastic piece selection and recovery apparatus for selectively recovering a specific type of plastic piece from a mixture containing a plurality of types of plastic pieces, wherein the heating is performed at a temperature determined according to the specific type of plastic piece. A heating member having a surface, and a contact member having a contact surface facing the heating surface, the contact member being provided facing the heating member, and allowing the mixture to contact the heating member by the contact member. And heating and heating, and selectively collects a specific type of plastic piece in the mixture by fusing it to the heating member.

[0008]

FIG. 1 shows a plastic piece selection and recovery apparatus 100 according to a first embodiment of the present invention. A plastic piece selection and recovery apparatus 100 for selectively recovering a mixture 1 composed of a plurality of types of plastic pieces,
It has the heating member 3 and the contact member 4, and the heating surface of the heating member and the contact surface of the contact member face each other. In this embodiment, the heating member 3 and the contact member 4 are plate-shaped members. The mixture 1 is composed of a plurality of types of plastic pieces such as polystyrene, polypropylene and polyethylene terephthalate. These plastic pieces are of substantially the same size, and if the heating surface and the contact surface are arranged horizontally facing each other, the mixture introduced between the heating member 3 and the contact member 4 The height of the plastic pieces becomes almost equal.

The heating member 3 having a heating surface is formed of a hard material, for example, metal, ceramic or polymer material. The heating member 3 is provided with a heating means (not shown) for heating the heating surface, for example, a ceramic heater, It has an accommodation section for accommodating an infrared heater, a heating wire, a nichrome wire or high-temperature oil. Alternatively, the heating surface of the heating member 3 may be coated with a material having high heat resistance and good releasability, for example, polytetrafluoroethylene or the like, to facilitate collecting plastic pieces. In the embodiment of the present invention, the heating member 3 has a thermocouple (not shown) on the heating surface, and the temperature of the heating surface is controlled to be constant by an external controller (not shown).

The temperature T _h0 of the heating surface of the heating member is approximated as follows. If the contact time between the heating surface of the heating member and the plastic piece is sufficiently short, the heat transfer effect between them can be approximated by the unsteady heat conduction between the two semi-infinite bodies. can be estimated temperature T _i of the interface between the analytically as follows. "Heat Conduction in Solid Materials (Second Edition)" by Carlslow and Jaeger, p. 88 (1959, Clarendon, Oxford) (Carslaw, HS and Jaeger, J.
C.:Conduction of Heat in Solids (second edition),
p.88 (1959) Oxford at the Clarendon Press).

[0011]

(Equation 1) Here, T _p0 is the initial temperature of the whole mixture including the plastic pieces to be selectively recovered. ρ, c and k indicate density, specific heat and thermal conductivity, respectively. The suffix p indicates the plastic piece to be selectively recovered, and the suffix h indicates the material of the heating surface of the heating member.

The temperature T _{i of} the interface expressed by the equation (1) is
Fusion start temperature T _m of a plastic strip be selected recovered
From the conditions exceeding, the temperature _Th0 of the heating surface of the heating member can be approximated by the following relational expression. The fusion start temperature is a temperature at which a part of the plastic piece starts to adhere to the heating surface by being melted by the heating surface of the heating member, and differs for each plastic material.

[0013]

(Equation 2) Therefore, the temperature of the heating member is obtained by an experiment based on the above-mentioned relational expression so as to enable a good fusion action.
Since the values of ρ, c and k, as well as T _m , depend on the plastic material used for the product or part,
For example, it is preferable to previously display these physical property values on a product or a part by engraving or the like so that the values of T _m , ρ, c, and k can be known. Thus, the temperature of the heating surface of the heating member can be easily set according to the values of T _m , ρ, c, and k, and the selective collection operation can be easily performed.

A mixture 1 consisting of a plurality of types of plastic pieces is introduced between a heating member 3 and a contact member 4 which are preset at a predetermined temperature in a plastic piece selection and recovery apparatus 100. Next, the mixture 1 is brought into contact with the heating member 3 by the contact member 4. The contact time and pressure for bringing the mixture 1 into contact with the heating member 3 are determined by the heat penetration distance from the heating surface of the heating member 3 to the inside of the plastic piece (the distance inside the plastic piece, where the plastic piece contacts the heating surface. From the point of contact to a point in the plastic piece having a temperature approximately equal to the temperature of this contact surface) is set to be smaller than the dimensions of the plastic piece. By bringing the mixture 1 into contact with the heating member, only a specific type of plastic piece 5 whose temperature at the contact interface between the mixture 1 and the heating member 3 exceeds the above-mentioned fusion starting temperature is fused to the heated surface. . Next, a specific type of plastic piece 5 can be selectively recovered from the mixture 1 by relatively moving the heating surface of the heating member 3 and the contact surface of the contact member 4 so as to be separated from each other. In the illustrated embodiment, only the heating member 3 is moved in a direction to approach or separate from the contact member 4, but only the contact member 4 or both the heating member 3 and the contact member 4 are moved, The separation operation described later can also be easily performed.

The contact member 4 can be formed from a hard or flexible material, but in an advantageous embodiment the contact member 4
Is preferably formed from a flexible material such as silicone rubber. Therefore, when there is a distribution in the representative length of the specific type of plastic pieces 5 in the mixture 1, such a difference in the representative length can be absorbed when the mixture 1 comes into contact. More specifically, when both the heating member and the contact member are formed of a hard material, a certain size of the plastic piece 5 contacts the heating member due to the presence of the larger size plastic piece 5. Therefore, only the large-sized plastic piece 5 is fused to the heating member. However, when at least one of the heating member and the contact member, for example, the contact member 4 is formed of a flexible material, these plastic pieces 5 having different representative lengths can be brought into contact with the heating member. 5 can be selectively recovered by fusing it to a heating member. Accordingly, the contact member 4 is preferably formed from a material that is sufficiently flexible to absorb such a distribution of representative lengths upon contact. In the embodiment shown in FIG. 1, the plate-like heating member 3 and the contact member 4 are shown, but at least one of these members is formed in a roller shape to continuously perform the selective collection operation. You can do it too.

In another advantageous embodiment, the contact element 4 has a cooling device (not shown) inside or outside the contact element 4, for example an air cooler, a water cooler or the like.
Thereby, it is preferable that the temperature of the contact member 4 does not change even if the contact member 4 receives the heating action of the heating member 3. Therefore, it is possible to prevent a specific type of plastic piece 5 from being fused to the contact member 4.

FIG. 2 shows a plastic piece selecting and collecting apparatus according to a second embodiment of the present invention. In this plastic piece selecting and collecting apparatus, the heating member 3 and the contact member 4 are each in the form of a roller, and these roller-shaped members are arranged in the direction shown in the drawing, that is, the heating member is clockwise.
The contact members rotate counterclockwise, respectively. Further, the plastic piece selection and recovery device of this embodiment includes a separation device 6,
For example, it has a plate-shaped member or a scraper-shaped member. The separating device 6 is disposed in contact with or adjacent to the heating member. In the illustrated embodiment, a plate-shaped separating device 6 is located downstream of the heating member 3 and the contact member 4 with respect to the moving direction of the mixture 1 and is in contact with or adjacent to the heating member 3. Heating member 3
Since the and the contact member 4 have a roller shape, the selective recovery operation of the specific type of plastic pieces 5 in the mixture 1 can be continuously performed. The plastic piece fused to the heating member 3 comes off the heating surface of the heating member 3 by coming into contact with the separation device 6. Although this embodiment shows the plate-shaped separating device 6, the plastic piece 5 can be separated from the heating member 3 by another method, for example, by vibrating the heating member 3. Further heating member 3
A cleaning device (not shown), for example, a solvent coating device, for removing contamination of the heated surface of the above is disposed to remove plastic pieces, for example, extremely small-sized plastic pieces, which have not been peeled off by the separating device. be able to. By disposing this cleaning device on the side opposite to the side of the heating member facing the contact member, it is possible to clean the heated surface that has performed the selective recovery operation.

In the third embodiment shown in FIG. 3, the plastic piece selecting and collecting apparatus further includes a holder 7 for storing the mixture and a transfer device 8 for transferring the mixture to the inlet 2 side, such as an air lift or a conveyor. I have it. The transport device 8 in this embodiment moves the mixture in the direction of arrow F along the transport path 9, for example, a pipe by flowing a fluid, for example, air or nitrogen.
The mixture from which only a part of the plastic pieces 5 has been removed by fusing to the heating member 3 is deposited in the holder 7 and moved to the entrance 2 side by the transfer device 8, and the selective collection operation is performed again. By repeating this operation,
The selective recovery rate for selectively recovering a specific type of plastic piece 5 from the mixture 1 can be increased.

In the embodiment shown, the transport device 8 transports the mixture 1 by a stream of a fluid, for example air or nitrogen. This fluid is relatively cool, so that the temperature of the mixture when it is conveyed to the inlet 2 side is approximately equal to the temperature of the mixture 1 newly introduced into the plastic piece selective recovery device. . As a result, the heat penetration distance of the mixture 1 where the first contact action is performed is substantially equal to the heat penetration distance of the mixture 1 where the second or more contact action is performed, and only the specific type of plastic piece 5 is removed. Can be recovered. The transport device is provided with a cooling member capable of cooling the mixture 1, such as an air cooler or a water cooling device, so that the mixture to be transported to the inlet 2 can be cooled. In the illustrated embodiment, the operation of transporting the mixture by the transport device 8 is performed continuously, but the mixture may be transported after a certain amount of the mixture 1 has been deposited. In this case, the energy required to supply the fluid by temporarily interrupting the flow of the fluid and the energy required to cool the mixture can be reduced.

FIG. 4 shows a two-stage plastic piece selective recovery device according to a fourth embodiment of the present invention. This plastic piece selecting and collecting apparatus is one in which two selective collecting sections each including the above-described plastic piece selecting and collecting apparatus shown in FIG. 3 are continuously arranged, and includes an openable and closable partition member 10, such as a valve or an openable and closable plate. It is provided between these two selective collection sections. After one or more selective collection operations, the partition member 10 is opened to remove the mixture 1 deposited in the holder 7 into the mixture 1.
To the plastic piece selection and recovery portion located on the downstream side with respect to the moving direction. The mixture introduced into the downstream plastic strip selective collection section contains no or almost no plastic strips 5 of a particular type. The plastic piece 15 having a higher fusion start temperature than the plastic piece 5 can be collected in the plastic piece selective collection portion on the downstream side. In such a multistage plastic piece selection and recovery apparatus, the temperature of the heating member of the plastic piece selection and recovery section located on the downstream side with respect to the moving direction of the mixture 1 is set to the temperature of the heating member of the plastic piece selection and recovery section located on the upstream side. Set higher than As a result, the plastic piece 5 having a lower fusing start temperature is selectively recovered in the selective recovery section on the upstream side, and then the plastic piece 15 having a higher fusing start temperature than the plastic piece 5 is selectively recovered in the selective recovery section on the downstream side. Can be done. As a matter of course, it is not necessary to provide the transport device 8. Also, whether the partition member 10 is always opened,
Alternatively, the selective collection operation can be continuously performed without installing the partition member. Furthermore, it is also possible to arrange three or more selective collecting portions similarly in succession to selectively collect various types of plastic pieces. In the illustrated embodiment, the temperature of the heating member of the plastic piece selection and recovery portion located on the downstream side is higher than the temperature of the heating member of the plastic piece selection and recovery portion located on the upstream side. Can be set substantially equal. In this case, a specific type of plastic piece 5
The selective collection rate can be increased.

FIG. 5 shows a multi-stage according to another embodiment of the present invention.
1 shows an apparatus for selectively recovering plastic pieces. This implementation
In the form, a plurality of heating members and contact members are provided.
ing. Mixture 1 is in the form of a movable conveyor
Along the arrow N while contacting the heating member 3
Move horizontally. In the illustrated embodiment
From three heating members set at almost the same temperature
Area A to be formed₁, A _TwoAnd A_nExists.
Each area A₁, A_TwoAnd A_nThe temperature of the heating member inside
It is set almost identical in the area, and the area A_TwoInside
The temperature of the heating member is area A₁Higher than the temperature of the heating element inside
Area A_nThe temperature of the heating member inside _TwoHeating section inside
It is set higher than the material temperature. Area A₁By
So that a specific type of plastic piece 5 can be selectively collected.
It has become. Then, the mixture 1 is in the region A_TwoMoved up
This area A_TwoThan the plastic piece 5
Plastic pieces 15 with high fusion start temperature are selectively collected
And then mixture 1 is in area A_nMoved up to this area
A_nPlastic pieces with even higher fusing start temperature
Are selectively collected. In this way,
Select and repeat multiple types of plastic pieces in mixture 1
Can be collected. As mentioned earlier, how to move the mixture
Plastic piece selection and recovery equipment located downstream in the direction
Plastic piece located upstream of the temperature of the heating element
The temperature is set higher than the temperature of the heating member of the selective collection device. This
Of course, the temperature of the heating element in each area
Set higher the further downstream in the direction of movement of the mixture.
You may. In this case, more types of plastic pieces
Can be selectively collected. Furthermore, as described above
Selective collection of plastic pieces with transfer device
Can be used in combination with each other.
Can also be used. Also, certain types of plastic pieces
Can be collected by dropping under its own weight. This place
In this case, no separation device is required.

[0022]

According to the invention described in each claim, a specific type of plastic piece is selectively recovered from a mixture of a plurality of types of plastic pieces by utilizing unsteady heat conduction and fusion phenomenon. It has a common effect. Further, according to the second aspect of the invention, it is possible to obtain an effect that a specific type of plastic piece can be selectively collected from a plastic product and easily recycled.

Further, according to the third aspect of the present invention,
There is an effect that the set temperature of the heating member can be easily determined from the displayed physical property values. Further, according to the inventions described in claims 5 and 17, it is possible to obtain an effect that the plastic pieces can be selectively collected continuously. Further, according to the inventions described in claims 6 and 18, even when there is a dimensional difference between the plastic pieces, it is possible to obtain an effect that a specific type of plastic piece can be selectively collected while absorbing the dimensional difference. .

Further, according to the inventions described in claims 7 and 19, it is possible to produce an effect that the plastic piece can be fused only to the heated surface without being fused to the contact surface. Further, according to the eighth and twentieth aspects of the invention, it is possible to provide an effect that the plastic pieces fused to the heating surface can be easily separated. Claims 9 and 21
According to the invention described in (1), the effect of increasing the selective collection rate can be obtained.

Further, according to the tenth and twenty-second aspects of the present invention, it is possible to obtain an effect that the heat penetration distance between the mixture subjected to the selective recovery operation and the mixture newly selectively recovered can be substantially equal. Claims 11, 13, and 2
According to the inventions described in 3 and 25, the plastic pieces can be easily transported by airflow, and the plastic pieces can be cooled.

Further, according to the twelfth and twenty-fourth aspects of the present invention, it is possible to obtain an effect of adopting a generally used conveyor to reduce the manufacturing cost. Further, according to the fifteenth aspect, it is possible to achieve an effect that the selective recovery rate of a specific type of plastic piece can be increased by using two heating members set at substantially the same temperature.

Further, according to the present invention, it is possible to selectively recover two types of plastic pieces by using two heating members set at different temperatures. Furthermore, according to the invention described in claim 26,
After the plastic piece of the specific type is almost completely selected and collected, it can be moved to the selective collection portion on the downstream side.

[Brief description of the drawings]

FIG. 1 is a side view of a plastic piece selective collection device according to a first embodiment of the present invention.

FIG. 2 is a side view of a plastic piece selecting and collecting apparatus according to a second embodiment of the present invention, which includes a roller-shaped heating member and a contact member.

FIG. 3 is a side view of a plastic piece selection and recovery device according to a third embodiment in which a transport device is attached to the embodiment shown in FIG. 2;

FIG. 4 is a side view of a two-stage plastic piece selecting and collecting apparatus in which two plastic piece selecting and collecting apparatuses shown in FIG. 3 are juxtaposed.

FIG. 5 is a side view of a multi-stage plastic piece selecting and collecting apparatus in which a moving path of a mixture is provided in a horizontal direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mixture 2 ... Inlet part 3 ... Heating member 4 ... Contact member 5 ... Plastic piece 6 ... Separation device 7 ... Holder 8 ... Transport device 9 ... Transport path 10 ... Partition member 100 ... Plastic piece selection and recovery device

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D004 AA07 BA06 CA04 CA08 CA22 CA32 CB08 CB13 CB31 CB42 CB43 CB44 CB46 CB47 DA01 DA02 DA06 4F301 AC14 AC15 AD02 BA15 BA21 BE06 BE07 BE11 BE30 BE32 BF10 BF12 BG21 BG22

Claims (26)

[Claims] 1. A method for selectively recovering a specific type of plastic piece from a mixture containing a plurality of types of plastic pieces, wherein the mixture is maintained at a temperature determined according to the specific type of plastic piece. A heating member having a heating surface is brought into contact with the mixture, the mixture is heated by the heating surface of the heating member, and a specific type of plastic piece in the mixture is fused to the heating surface of the heating member to form the plastic piece. A method for selecting and collecting plastic pieces. 2. The method according to claim 1, wherein the mixture is formed by crushing a plastic product into plastic pieces. 3. The temperature of the heating surface of the heating member is determined based on the physical property value of the plastic material for determining the temperature of the heating surface, based on the physical property value.
4. The method for selecting and recovering plastic pieces according to item 1. 4. A plastic piece selection and recovery apparatus for selectively recovering a specific type of plastic piece from a mixture containing a plurality of types of plastic pieces, comprising a heating surface maintained at a temperature determined according to the specific type of plastic piece. A heating member, comprising a contact member having a contact surface facing the heating surface and provided to face the heating member, and heating the mixture by contacting the mixture with the heating member by the contact member. And a plastic piece selection and recovery apparatus, wherein a specific type of plastic piece in the mixture is selectively fused to the heating member and recovered. 5. The plastic piece selective collection device according to claim 4, wherein at least one of the heating member and the contact member has a roller shape. 6. The apparatus according to claim 4, wherein the contact surface is formed of a flexible material. 7. The plastic piece selective collection device according to claim 4, wherein the contact member has a cooling device for cooling the contact surface. 8. The heating device according to claim 4, further comprising a separating unit provided adjacent to the heating member, for separating a plastic piece fused to a heating surface of the heating member from the heating surface. Item 4. The plastic piece selection and recovery device according to the above item. 9. The apparatus according to claim 4, further comprising a circulation device for re-supplying the mixture, in which a specific type of plastic piece is selectively recovered, between the heating surface and the contact surface.
The plastic piece selective collection device according to any one of the above. 10. The plastic piece selection and recovery device according to claim 9, wherein the circulation device includes a cooling device for cooling the mixture from which a specific type of plastic piece has been selectively recovered. 11. The plastic piece selection and recovery device according to claim 9, wherein the circulation device includes a gas transport device that transports the mixture from which a specific type of plastic piece is selectively recovered by an air flow. 12. The plastic piece selective collection device according to claim 9, wherein the circulation device is a conveyor. 13. The plastic piece selective collection device according to claim 9, wherein the circulation device is an air lift. 14. A heating element provided on the upstream side with respect to the flow of the mixture and having a first heating surface, and a heating element provided on the downstream side with a second heating surface. Comprising a second heating member having a first contact member provided with a first contact surface facing the first heating surface and facing the first heating member, A second contact member having a second contact surface facing the second heating surface, and a second contact member provided facing the second heating member, wherein the first contact member provides the mixture. Is heated by contacting the first heating member, a specific type of plastic pieces in the mixture is selectively fused and recovered to the first heating member, and then by the second contact member The mixture is heated by being brought into contact with the second heating member, Plastic strip selecting recovery apparatus and recovering by selectively fusing the plastic pieces of the kind in the second heating member. 15. The plastic piece selective collection according to claim 14, wherein the temperatures of the first heating surface of the first heating member and the second heating surface of the second heating member are substantially equal. apparatus. 16. The plastic piece according to claim 14, wherein a temperature of the second heating surface of the second heating member is higher than a temperature of the first heating surface of the first heating member. Selective collection device. 17. The apparatus according to claim 14, wherein at least one of the first heating member, the first contact member, the second heating member, and the second contact member has a roller shape.
7. The plastic piece selective collection device according to any one of 6. 18. The plastic piece selective collection device according to claim 14, wherein at least one of the first contact surface and the second contact surface is formed of a flexible material. 19. The plastic according to claim 14, wherein at least one of the first contact member and the second contact member has a cooling device for cooling the contact surface. Piece selection and recovery device. 20. Further, provided adjacent to at least one of the first heating member and the second heating member,
20. The apparatus for selectively recovering plastic pieces according to any one of claims 14 to 19, further comprising separating means for separating the plastic pieces fused to the heating surface of the heating member from the heating surface. 21. A circulating device for re-supplying the mixture from which a specific type of plastic piece is selectively recovered between the first heating surface and the first contact surface, and a specific type of plastic. 2. The apparatus according to claim 1, further comprising at least one circulating device for re-supplying the mixture from which the pieces have been selectively recovered between the second heating surface and the second contact surface.
21. The plastic piece selective collection device according to any one of 4 to 20. 22. The apparatus for selectively recovering plastic pieces according to claim 21, wherein the circulating apparatus includes a cooling apparatus for cooling the mixture from which a specific type of plastic piece has been selectively recovered. 23. The plastic piece selective recovery device according to claim 21, wherein the circulation device includes a gas transport device that conveys the mixture from which a specific type of plastic piece is selectively recovered by an air flow. 24. The apparatus according to claim 21, wherein the circulation device is a conveyor. 25. The plastic piece selective collection device according to claim 21, wherein the circulation device is an air lift. 26. The apparatus according to claim 14, further comprising a partition member that can be opened and closed between the first heating member and the first contact member, and the second heating member and the second contact member. The plastic piece selection and recovery device according to claim 1.