JP2023106978A - Plastic separation system and plastic separation method - Google Patents

Abstract

The present invention separates chlorine-rich plastics to increase the recovery of chlorine-reduced recyclable plastics. A specific gravity separating means configured to be able to separate plastic according to its specific gravity, and a specific gravity separating means provided downstream of the specific gravity separating means along the transport direction of the plastic so as to be capable of separating the plastic according to the material of the plastic. A plastic separation system for separating plastics into a predetermined classification executes a specific gravity separation step of separating plastics according to specific gravity by the specific gravity separation means, and the material judgment separation means performs specific gravity separation A material determination process is executed to separate the plastic separated by the process according to the material of the plastic. [Selection drawing] Fig. 1

Description

The present invention relates to a plastic separation system and a plastic separation method.

Conventionally, in order to realize a low-carbon society and a recycling-oriented society, various demands have been made also in the field of waste disposal. In response to such a demand, various waste plastic sorting techniques have been specifically proposed for sorting waste plastics for recycling from wastes containing plastics that will become recyclable waste.

Patent document 1 describes a dry separation process for detecting the composition of plastic waste materials composed of multiple types of plastics, selectively recovering plastic waste materials with a desired composition, and sorting out plastics with a specific composition to be recycled. A screening method is disclosed that includes a recovering high-purity separation and recovery step.

Patent Document 2 describes an optical sorting device that sorts out recycled plastics based on the difference in wavelength absorbance depending on the material, and a centrifuge that increases the purity of the recycled plastic based on the difference in specific gravity depending on the material. There is disclosed a technology of a plastic separation system that separates at least one kind of recycled plastics as recycled plastics by type by processing waste plastics using an optical sorting device and a centrifuge.

JP 2010-208085 A JP 2017-170653 A

However, in the above-mentioned prior art, it is difficult to separate chlorine content such as chlorine-based polyolefin used as adhesive parts and composite materials of plastic products such as polyethylene (PolyEthylene: PE) and polypropylene (PolyPropylene: PP). was extremely difficult. Therefore, it has been desired to develop a technique capable of separating plastics with high chlorine content and increasing the recovery rate of recyclable plastics with reduced chlorine content.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and an object of the present invention is to provide a plastic separation system and a plastic that can separate high-chlorine plastics and increase the recovery rate of chlorine-reduced recyclable plastics. The object is to provide a separation method.

In order to solve the above-described problems and achieve the object, a plastic separation system according to one aspect of the present invention is a plastic separation system configured to be able to separate plastics into a predetermined classification, wherein the plastics are divided into and a specific gravity separating means configured to be able to separate according to the material of the plastic, and a material determination separation provided at a stage subsequent to the specific gravity separating means along the conveying direction of the plastic and configured to be able to separate the plastic according to the material of the plastic. a means;

In the plastic separation system according to one aspect of the present invention, in the above-described invention, the specific gravity separation means separates the plastic into two types: a light material having a specific gravity less than a predetermined value and a heavy material having a specific gravity equal to or greater than the predetermined value. The material determining and separating means determines the material of the heavy material and separates the heavy material into at least two types.

In the plastic separation system according to one aspect of the present invention, in the above invention, crushing processing means configured to crush the plastic is provided on the upstream side of the material determination separation means.

In this configuration of the plastic separation system according to one aspect of the present invention, the crushing means is configured to be capable of crushing the plastic to a crushed particle size of 100 mm or less after crushing.

In the plastic separation system according to one aspect of the present invention, in the above invention, the specific gravity separation means is configured to be capable of performing floating-sink type specific gravity separation using water as a medium.

In the plastic separation system according to one aspect of the present invention, in the invention described above, the material determination separation means is configured to select at least one of polyethylene terephthalate and polystyrene resins and separate them.

In the plastic separation system according to one aspect of the present invention, in the above invention, the material determination separation means selects at least one of polyvinyl chloride, polyvinylidene chloride, polyethylene, and polypropylene and is configured to be able to separate. ing.

A method for separating plastics according to one aspect of the present invention is a method for separating plastics into predetermined categories, comprising a specific gravity separation step of separating the plastics according to specific gravity, and the plastics separated by the specific gravity separation step. and a material determination step of separating the plastic according to the material of the plastic.

In the method for separating plastics according to one aspect of the present invention, in the specific gravity separation step, the plastic is divided into two types: a light material having a specific gravity less than a predetermined value and a heavy material having a specific gravity equal to or greater than the predetermined value. In the material determination step, the heavy materials are separated into at least two types by determining the materials of the heavy materials.

In the plastic separation method according to one aspect of the present invention, in this configuration, the predetermined value in the specific gravity separation step is 1.

A plastic separation method according to an aspect of the present invention further includes a crushing treatment step of crushing the plastic in the above invention before the material determination step.

In the plastic separation method according to one aspect of the present invention, in the above invention, at least one of polyethylene terephthalate and polystyrene resin is selected and separated from the plastic in the material determination step.

In the method for separating plastics according to one aspect of the present invention, in the above invention, at least one of polyvinyl chloride, polyvinylidene chloride, polyethylene, and polypropylene is selected and separated from the plastic in the material determination step. .

The plastic separation system and method according to the present invention enables the separation of chlorine-rich plastics to increase the recovery of chlorine-reduced recyclable plastics.

FIG. 1 is a block diagram that schematically illustrates a plastic separation system according to one embodiment of the invention. FIG. 2 is a schematic diagram showing the configuration of a material judgment separation device according to an embodiment of the present invention.

An embodiment of the present invention will be described below with reference to the drawings. In addition, in all the drawings of the following one embodiment, the same reference numerals are given to the same or corresponding parts. Moreover, the present invention is not limited to the one embodiment described below.

First, before describing an embodiment of the present invention, in order to facilitate the understanding of the present invention, the earnest studies conducted by the inventors to solve the above problems will be described.

That is, according to the findings of the present inventor, as a technique for separating chlorine from plastic, there is a technique for detecting and sorting polyvinyl chloride (PVC) by absorption detection using near-infrared rays. However, in this prior art, separation of chlorine contained in polyethylene (PE) and polypropylene (PolyPropylene: PP) is extremely difficult and practically impossible. Further, according to the findings of the present inventor, there is a technique for sorting waste plastics into light plastics with a low specific gravity and heavy plastics with a high specific gravity. However, according to this prior art, the chlorine content is concentrated on the side sorted out as a heavy plastic with a high specific gravity. For this reason, heavy-duty plastics are limited in usage such as recycling. Specifically, when plastics made of PE, PP, etc. are recycled, it is extremely difficult to remove the chlorine content of chlorinated polyolefins, etc., which are used as adhesives or composite materials for plastic products using PE or PP. .

Therefore, in the process of sorting out waste plastics, the present inventor first developed a specific gravity separation process in which light plastics having a specific gravity below a predetermined value and heavy plastics having a specific gravity greater than or equal to a predetermined value are separated by specific gravity separation, as in the conventional method. We conducted an intensive study on the premise that Here, the predetermined value varies depending on the density of the liquid used for gravity separation, but the predetermined value is 1 when the liquid used for gravity separation is water.

The present inventor conducted extensive research and devised a method of performing a material determination process using near-infrared rays, etc. for heavy plastics having a specific gravity of a predetermined value or more (for example, 1 or more) obtained by the specific gravity separation process. bottom. In the devised material determination process, polyethylene terephthalate (PET) and polystyrene resin (PolyStyrene: PS) are determined and separated and recovered. This makes it possible to obtain waste plastic with reduced chlorine content. It was also confirmed that plastics with a high chlorine content could be recovered by separating PVC, PE, and PP in the material determination process.

The present inventors further studied a method for separating the chlorine contained in plastics made of PE and PP. We devised a method of carrying out a crushing treatment step in which the powder is crushed to a particle size of less than the crushed particle size, specifically, for example, 100 mm or less, preferably 50 mm or less. In this pulverization process, by pulverizing the plastic, it is possible to separate the chlorine contained in the unevenly distributed chlorine-based olefins used in PE and PP plastics from PE and PP that do not contain chlorine. There was found. The present invention has been devised based on the above earnest studies.

(plastic separation system)
First, a plastic separation system according to one embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing a plastic separation system 1 according to this embodiment.

As shown in FIG. 1, the plastic separation system 1 according to the present embodiment comprises a specific gravity separation device 10, a material determination separation device 20, and a crushing processing device 30. As shown in FIG. The material judgment separation device 20 is provided downstream of the specific gravity separation device 10 along the conveying direction of the waste plastic, that is, on the downstream side. The shredding device 30 as a shredding means is provided at least upstream of the material judging and separating device 20, i.e., upstream along the transport direction of the waste plastics, and typically upstream of the specific gravity separating device 10, i.e., upstream. is provided. The crushing device 30 is configured to be able to crush the introduced waste plastics to a predetermined crushing particle size or less, specifically, for example, 100 mm or less, preferably 50 mm or less. In addition, it is also possible not to provide the crushing apparatus 30. FIG.

The specific gravity separation device 10 as a specific gravity separation means is composed of a conventionally known device such as a dry specific gravity separator or a wet specific gravity separator. As the specific gravity separator 10, a floating/sinking wet specific gravity separator, a centrifugal wet specific gravity separator, or the like is preferably adopted, but is not limited thereto. The liquid used in the wet specific gravity separator is, for example, water (with a specific gravity of 1), but other liquids can also be used. That is, the liquid to be used can be selected according to the desired specific gravity for separating light and heavy plastics.

In the recycling of waste plastics, waste plastics containing chlorine at a predetermined ratio are introduced into the specific gravity separator 10 . When the plastic separation system 1 is equipped with the crushing device 30, the chlorine content of the waste plastic is, for example, about 1% in this embodiment, but the chlorine content varies depending on the properties of the waste plastic. Yes, but not limited to this number. Waste plastics do not normally include waste plastics derived from home electric appliances, waste plastics derived from PET bottles, and the like, but are not necessarily limited. That is, plastics to be treated as waste plastics are appropriately set.

PE and PP, which are contained in waste plastic and do not contain chlorine-based polyolefin, have a specific gravity of less than a predetermined value, for example, less than 1. Therefore, in the specific gravity separator 10, it is possible to separate and recover light waste plastics that mainly contain PE, PP, etc. that do not contain chlorine-based polyolefins. Material recycling (also referred to as material recycling, material regeneration, recycling, or recycling) can be performed on the separated and collected waste plastics as light materials. In this case, the chlorine content is reduced compared to the chlorine content in the waste plastic introduced into the gravity separator 10 . In this embodiment, the chlorine content is reduced to about 0.2%, which is about 1/5, for example. In addition, the recovery rate of waste plastics mainly containing PE, PP, etc. recovered as light materials is, for example, about 70% with respect to the amount of introduced waste plastics in this embodiment.

On the other hand, in the specific gravity separator 10, chlorine-containing plastics such as PVC and PolyVinyliDene Chloride (PVDC) having a specific gravity equal to or higher than a predetermined value, for example, 1 or higher, are sorted out and carried out. Moreover, since PET and PS have a specific gravity of 1 or more, they are sorted out as heavy waste plastics by the specific gravity separator 10 and carried out. Furthermore, in PE and PP used for container packaging plastics, chlorinated olefins are used as adhesive parts, printed parts, or composite materials. Here, PE and PP using chlorine-based olefins are discharged from the specific gravity separator 10 as heavy waste plastics having a specific gravity of 1 or more. That is, the heavy waste plastic discharged from the gravity separator 10 is a mixture of chlorine-containing PE or PP, PET, PS, PVC, and PVDC. Here, the transport rate of waste plastics of the heavy materials transported is (100-70=) about 30%. In addition, the chlorine content in the heavy waste plastics carried out increases compared to the chlorine content in the waste plastics introduced into the gravity separator 10 . In this embodiment, the chlorine content increases, for example, by about 2.5 times to about 2.5%. In the prior art, the heavy waste plastic is used as a residue for thermal recycling or the like.

In the prior art, heavy waste plastic discharged from the gravity separator 10 is treated as residue. That is, in the prior art, chlorine-containing PE and PP are collected together with PET, PS, PVC, PVDC, etc., and separation of chlorine has been extremely difficult.

On the other hand, in the present embodiment, the heavy waste plastic carried out from the specific gravity separation device 10 is carried into the material judgment separation device 20 . If the plastic separation system 1 is provided with the crushing device 30 , the waste plastics are crushed by the crushing device 30 to a predetermined size or less and carried into the material judgment separation device 20 .

FIG. 2 is a schematic diagram showing the material determination separation device 20 used in this embodiment. As shown in FIG. 2, the material determination and separation device 20 includes a controller 21, a conveyor 22 having rollers 22a, a near-infrared sensor 23, a gas supply unit 24, a gas injection unit 25, and a collection having separation and collection trays 26a and 26b. It is configured with a unit 26 .

In the material judgment separation device 20 as the material judgment separation means, the control section 21 controls the elements of each section of the material judgment separation device 20 . That is, the controller 21 controls the conveyor 22 , the near-infrared sensor 23 , and the gas supply section 24 . Heavy waste plastic discharged from the specific gravity separation device 10 is carried into the material determination separation device 20 .

The heavy waste plastic carried in is conveyed by the conveyor 22 as the rollers 22a rotate. The near-infrared sensor 23 identifies the material of the waste plastic by irradiating the waste plastic on the conveyor 22 with the near-infrared light L and receiving the reflected near-infrared light. Sensor information of the near-infrared light detected by the near-infrared sensor 23 is output to the control unit 21 .

Based on the input sensor information, the control unit 21 controls the gas supply unit 24 to inject the gas A such as air from the gas injection unit 25 on the carry-out side of the conveyor 22 at a predetermined timing. do the jet. Thus, the waste plastics Sa and Sb of different materials are classified. Specifically, waste plastics Sa such as PET and PS with a low chlorine content and waste plastics Sb such as PE, PP, PVC and PVCD with a high chlorine content are placed in separate recovery trays 26a and 26b, respectively. separated and collected. As a result, the waste plastics Sa and Sb are classified into a low-content waste plastic Sa with a low chlorine content and a high-content waste plastic Sb with a high chlorine content, which is a residue. It should be noted that PE, PP, and PVC may be separated and collected by material determination.

Here, the recovery rate of low content waste plastic Sa is, for example, about 15% with respect to the amount of waste plastic introduced into the plastic separation system 1, and the chlorine content is reduced to, for example, less than 1%. As shown in FIG. 1, waste plastic Sa with a low content can be subjected to chemical recycling in which the composition is converted by a chemical reaction and then recycled, or the material recycling described above.

On the other hand, the recovery rate of high-content waste plastic Sb recovered as residue is (30-15=) about 15%, and the chlorine content increases to about 4%, which is about four times the initial content. That is, in the plastic separation system 1, about 15% of the amount of waste plastic introduced becomes a residue, which is used for thermal recycling or the like.

According to the embodiment described above, the plastic separation system 1 is configured with the material determination separator 20 in the rear stage of the specific gravity separator 10, and further, in the front stage of the specific gravity separator 10 and the material determination separator 20, By providing the crushing device 30, it is possible to recover the waste plastic with a reduced chlorine content.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-described embodiments, and various modifications based on the technical idea of the present invention are possible. For example, the numerical values given in the above-described embodiments are merely examples, and different numerical values may be used as necessary. The present invention also includes configurations obtained by appropriately combining the constituent elements of the above-described embodiments and modifications. Further effects and modifications can be easily derived by those skilled in the art. The broader aspects of the invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and equivalents thereof.

For example, in the above-described embodiment, the content of chlorine contained in the waste plastics to be fed into the plastic separation system 1, the ratio of separation in the specific gravity separator 10 and the material determination separator 20, etc. are merely examples. Various values can be taken depending on the properties of the waste plastic.

In the above-described embodiment, the crushing device 30 is arranged before the specific gravity separation device 10, but the crushing device 30 is arranged after the gravity separation device 10 and before the material determination separation device 20, that is, It can also be provided between the specific gravity separation device 10 and the material determination separation device 20 .

In the above-described embodiment, the specific gravity separation device 10 separates the waste plastic into two types, light waste plastic and heavy waste plastic. It may be separated as above. In that case, the waste plastic to be fed into the subsequent material determination/separation device 20 can be the waste plastic with the highest specific gravity.

In the above-described embodiment, the material determination and separation device 20 separates heavy waste plastics Sa with low chlorine content and high content chlorine residue waste plastic Sa with high chlorine content. Although it is separated into two kinds of waste plastic Sb, it is also possible to separate into three or more kinds. Of the waste plastics separated into three or more types, the waste plastic with the highest chlorine content can be used as residue, and the waste plastic with the lowest chlorine content can be used for chemical recycling or material recycling. be.

1 Plastic separation system 10 Gravity separation device 20 Material determination separation device 21 Control unit 22 Conveyor 22a Roller 23 Near-infrared sensor 24 Gas supply unit 25 Gas injection unit 26 Recovery unit 26a, 26b Separation recovery tray 30 Crushing device A Gas L Near-infrared rays Sa, Sb Waste plastic

Claims (13)

A plastic separation system configured to separate plastics into predetermined categories,
a specific gravity separating means capable of separating the plastic according to its specific gravity;
A plastic separation system, further comprising a material determination separation means provided after the specific gravity separation means along the conveying direction of the plastic and configured to be able to separate the plastic according to the material of the plastic. The specific gravity separating means separates the plastic into two types, a light material having a specific gravity less than a predetermined value and a heavy material having a specific gravity equal to or higher than the predetermined value,
2. The plastic separating system according to claim 1, wherein the material determining and separating means determines the material of the heavy material and separates the heavy material into at least two types. 3. The plastic separating system according to claim 1, further comprising crushing processing means capable of crushing the plastic, provided upstream of the material determination separating means. 4. The plastic separating system according to claim 3, wherein the crushing means is capable of crushing the plastic to a crushed particle size of 100 mm or less after crushing. The plastic separation system according to any one of claims 1 to 4, wherein the specific gravity separation means is configured to be capable of performing floating-sink type specific gravity separation using water as a medium. 6. The plastic separation system according to any one of claims 1 to 5, wherein the material determination separation means is configured to be separable by selecting at least one of polyethylene terephthalate and polystyrene resin. The plastic separation according to any one of claims 1 to 5, wherein the material determination separation means is configured to be able to select and separate at least one of polyvinyl chloride, polyvinylidene chloride, polyethylene, and polypropylene. system. A plastic separation method for separating plastics into predetermined categories,
a specific gravity separation step of separating the plastic according to specific gravity;
and a material determination step of separating the plastic separated by the specific gravity separation step according to the material of the plastic. In the specific gravity separation step, the plastic is separated into two types, a light material having a specific gravity less than a predetermined value and a heavy material having a specific gravity equal to or higher than the predetermined value,
9. The method of separating plastics according to claim 8, wherein in the material determination step, the heavy material is separated into at least two types by determining the material of the heavy material. 10. The method of separating plastics according to claim 9, wherein the predetermined value in the specific gravity separation step is 1. The plastic separation method according to any one of claims 8 to 10, further comprising a crushing treatment step of crushing the plastic before the material determination step. The plastic separation method according to any one of claims 8 to 11, wherein at least one of polyethylene terephthalate and polystyrene resin is selected and separated from the plastic in the material determination step. The plastic separation method according to any one of claims 8 to 11, wherein at least one of polyvinyl chloride, polyvinylidene chloride, polyethylene, and polypropylene is selected and separated from the plastic in the material determination step.

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