Plastic separation system and method

Abstract

To provide a system and a method for separation of plastics with a high chlorine content and increasing a recovery rate of recyclable plastics with a reduced chlorine content.SOLUTION: A plastic separation system for separating plastics according to predetermined classification, includes: specific gravity separation configured so as to separate the plastics according to the specific gravities; and material determination separation means provided in a subsequent stage of the specific gravity separation means along a transportation direction of the plastics and configured so as to separate the plastics according to materials of the plastics. A plastic separation method includes: a specific gravity separation step of separating the plastics according to the specific gravities executed by the specific gravity separation means; and a material determination step of separating the plastics separated in the specific gravity separation step according to the materials of the plastics executed by the specific gravity separation means.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a plastic separation system and method. [Background technology]

[0002] In order to realize a low-carbon society and a recycling-oriented society, various demands have been made in the field of waste disposal. In response to these demands, various waste plastic sorting techniques have been proposed, specifically for sorting waste plastics for recycling from waste containing plastics that can be used as resource waste.

[0003] Patent Document 1 discloses a sorting method that includes a dry separation process that detects the composition of plastic waste made up of multiple types of plastics and selectively recovers plastic waste with a desired composition, and a high-purity separation and recovery process that selectively recovers plastics with a specific composition to be recycled.

[0004] Patent Document 2 discloses a technology for a plastic separation system that includes an optical sorting device that sorts recycled plastics based on differences in wavelength absorption between materials, and a centrifuge that increases the purity of recycled plastics based on differences in specific gravity between materials, and that processes waste plastics using the optical sorting device and the centrifuge to sort at least one type of recycled plastic as a type of recycled plastic. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-208085 [Patent Document 2] Japanese Patent Application Publication No. 2017-170653 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the above-mentioned conventional technologies, it has been extremely difficult to separate chlorine from chlorine-containing polyolefins, which are used as adhesives or composite materials in products made of plastics such as polyethylene (PE) and polypropylene (PP). Therefore, there has been a demand for the development of a technology that can separate plastics with high chlorine content and increase the recovery rate of recyclable plastics with reduced chlorine content.

[0007] The present invention has been made in view of the above, and its object is to provide a plastic separation system and a plastic separation method that can separate plastics with high chlorine content and increase the recovery rate of recyclable plastics with reduced chlorine content. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the objectives, one aspect of the present invention is a plastic separation system configured to be able to separate plastics into predetermined classifications, and is equipped with a specific gravity separation means configured to be able to separate the plastics according to their specific gravity, and a material determination separation means that is provided downstream of the specific gravity separation means along the conveying direction of the plastics and is configured to be able to separate the plastics according to the material of the plastics.

[0009] In one embodiment of the plastic separation system of the present invention, in the above invention, the specific gravity separation means separates the plastics into two types: light materials with specific gravities less than a predetermined value and heavy materials with specific gravities equal to or greater than the predetermined value, and the material determination separation means determines the material of the heavy materials and separates the heavy materials into at least two types.

[0010] In the plastic separation system according to one aspect of the present invention, in the above invention, a crushing means configured to be able to crush the plastic is provided upstream of the material determination and separation means.

[0011] In this configuration of the plastic separation system according to one embodiment of the present invention, the crushing means is configured to crush the plastics to a crushed particle size of 100 mm or less after crushing.

[0012] 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 able to perform sink-float type specific gravity separation using water as a medium.

[0013] In the plastic separation system according to one aspect of the present invention, in the above invention, the material determination and separation means is configured to be able to select and separate at least one of polyethylene terephthalate and polystyrene resin.

[0014] In one aspect of the plastic separation system of the present invention, in the above invention, the material determination and separation means is configured to be able to select and separate at least one of polyvinyl chloride, polyvinylidene chloride, polyethylene, and polypropylene.

[0015] A plastic separation method according to one embodiment of the present invention is a plastic separation method for separating plastics into predetermined classifications, and includes a specific gravity separation process for separating the plastics according to their specific gravity, and a material determination process for separating the plastics separated by the specific gravity separation process according to the material of the plastics.

[0016] In one embodiment of the plastic separation method of the present invention, in the above invention, in the specific gravity separation process, the plastics are separated into two types: light materials with specific gravities below a predetermined value and heavy materials with specific gravities equal to or greater than the predetermined value, and in the material determination process, the heavy materials are separated into at least two types by determining the material of the heavy materials.

[0017] In this configuration of the plastic separation method according to one aspect of the present invention, the predetermined value in the specific gravity separation step is 1.

[0018] In accordance with one aspect of the present invention, in the above-described plastic separation method, the method further includes a crushing process step of crushing the plastic before the material determination process.

[0019] 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.

[0020] In the plastic separation method 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 plastics in the material determination step. [Effects of the Invention]

[0021] The plastic separation system and method of the present invention can separate high chlorine content plastics and increase the recovery rate of recyclable plastics with reduced chlorine content. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a block diagram that schematically illustrates a plastic separation system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of a material determination and separation device according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the embodiment below, the same or corresponding parts are designated by the same reference numerals. Furthermore, the present invention is not limited to the embodiment described below.

[0024] First, before describing one embodiment of the present invention, in order to facilitate understanding of the present invention, the inventors will explain the extensive research they have conducted to solve the above-mentioned problems.

[0025] Specifically, according to the inventor's findings, there is a technology for separating chlorine from plastics that detects and separates polyvinyl chloride (PVC) using near-infrared absorption detection, etc. However, with this conventional technology, it is extremely difficult, and in fact impossible, to separate the chlorine contained in polyethylene (PE) and polypropylene (PP). Furthermore, according to the inventor's findings, there is a technology for sorting waste plastics by specific gravity to separate light plastics with low specific gravity and heavy plastics with high specific gravity. However, with this conventional technology, chlorine is concentrated in the heavy plastics with high specific gravity. Therefore, the utilization methods of heavy plastics, such as recycling, are limited. Specifically, when recycling plastics made of PE or PP, it is extremely difficult to remove chlorine from chlorine-based polyolefins used in adhesive joints or composite materials in plastic products made of PE or PP.

[0026] Therefore, the inventors have conducted extensive research on the premise that in the process of sorting waste plastics, a gravity separation process is first carried out, as in the conventional process, to separate light plastics with a specific gravity below a predetermined value from heavy plastics with a specific gravity above the predetermined value. Here, the predetermined value varies depending on the density of the liquid used for gravity separation, but when the liquid used for gravity separation is water, the predetermined value is 1.

[0027] After extensive research, the inventors have devised a method for performing a material determination process using near-infrared rays or the like on heavy plastics with specific gravities above a predetermined value (e.g., 1 or above) obtained through the gravity separation process. In the devised material determination process, polyethylene terephthalate (PET) and polystyrene resin (PS) are determined and separated for recovery. This allows for the production of waste plastics with reduced chlorine content. It has also been confirmed that plastics with high chlorine content can be recovered by separating PVC, PE, and PP in the material determination process.

[0028] The inventors further investigated methods for separating chlorine from plastics made of PE and PP, and devised a method in which a crushing process is carried out at least prior to the material determination process, typically prior to the gravity separation process, in which the plastic is crushed to a predetermined crush size or less, specifically 100 mm or less, preferably 50 mm or less. It was found that by crushing the plastic in this crushing process, it is possible to separate the plastic into chlorine contained in chlorine-based olefins, which are widely distributed in PE and PP plastics, and chlorine-free PE and PP. The present invention was devised based on the above-mentioned extensive investigations.

[0029] (Plastic Separation System) First, a plastic separation system according to an embodiment of the present invention will be described. Fig. 1 is a schematic diagram showing a plastic separation system 1 according to this embodiment.

[0030] As shown in FIG. 1, the plastic separation system 1 according to this embodiment is configured to include a gravity separator 10, a material determination separator 20, and a shredding / processing device 30. The material determination separator 20 is provided downstream of the gravity separator 10 in the direction of transport of the waste plastic. The shredding / processing device 30, which serves as a shredding / processing means, is provided at least upstream of the material determination separator 20, in other words, upstream of the direction of transport of the waste plastic, and is typically provided upstream of the gravity separator 10. The shredding / processing device 30 is configured to crush the introduced waste plastic to a predetermined crush size or smaller, specifically, for example, 100 mm or smaller, preferably 50 mm or smaller. Note that the shredding / processing device 30 may not be provided.

[0031] The gravity separator 10, which serves as the gravity separation means, is composed of a conventionally known device such as a dry gravity separator or a wet gravity separator. The gravity separator 10 is preferably, but not limited to, a sink-float wet gravity separator or a centrifugal wet gravity separator. The liquid used in the wet gravity separator is, for example, water (specific gravity 1), but other liquids can also be used. In other words, the liquid to be used can be selected depending on the desired specific gravity for separating light plastics from heavy plastics.

[0032] In the recycling of waste plastics, waste plastics containing a predetermined percentage of chlorine are introduced into the gravity separator 10. When the plastic separation system 1 is equipped with the shredding and processing device 30, the chlorine content of the waste plastics is, for example, about 1% in this embodiment, but the chlorine content varies depending on the properties of the waste plastics and is not limited to this value. Note that waste plastics do not usually include waste plastics derived from home appliances or PET bottles, but this is not necessarily limited to this. In other words, the plastics that are treated as waste plastics are set appropriately.

[0033] The specific gravity of PE and PP contained in waste plastics and not containing chlorine-based polyolefins is less than a predetermined value, for example, less than 1. Therefore, the gravity separation device 10 can separate and recover light waste plastics mainly containing PE and PP not containing chlorine-based polyolefins. The separated and recovered light waste plastics can be subjected to material recycling (also referred to as material recycling, material regeneration, resource recovery, or recycling). In this case, the chlorine content is reduced compared to the chlorine content in the waste plastic introduced into the gravity separation device 10. In this embodiment, the chlorine content is reduced to, for example, about 0.2%, which is about 1 / 5. In addition, in this embodiment, the recovery rate of waste plastics mainly containing PE and PP recovered as light materials relative to the amount of introduced waste plastic is, for example, about 70%.

[0034] Meanwhile, in the gravity separator 10, chlorine-containing plastics such as PVC and polyvinylidene chloride (PVDC), which have a specific gravity of a predetermined value or more, for example, 1 or more, are sorted and discharged. Also, since PET and PS also have a specific gravity of 1 or more, they are sorted and discharged as heavy waste plastics in the gravity separator 10. Furthermore, PE and PP used in plastic container packaging contain chlorine-containing olefins in adhesives, printed areas, or composite materials. Here, PE and PP containing chlorine-containing olefins are discharged from the gravity separator 10 as heavy waste plastics with a specific gravity of 1 or more. In other words, the heavy waste plastics discharged from the gravity separator 10 are a mixture of chlorine-containing PE and PP with PET, PS, PVC, and PVDC. The discharge rate of heavy waste plastics discharged here is approximately 30% (100-70=). Furthermore, the chlorine content of the discharged heavy waste plastics increases compared to the chlorine content of the waste plastics introduced into the gravity separation device 10. In this embodiment, the chlorine content increases to, for example, about 2.5%, which is about 2.5 times the original amount. In the prior art, this heavy waste plastic is used as residue for thermal recycling or the like.

[0035] In the prior art, the heavy waste plastics discharged from the gravity separator 10 are treated as residue. In other words, in the prior art, PE and PP containing chlorine are collected together with PET, PS, PVC, PVDC, etc., making it extremely difficult to separate the chlorine content.

[0036] In contrast to this, in this embodiment, the heavy waste plastics discharged from the gravity separator 10 are transported to the material determination separation device 20. If the plastic separation system 1 is provided with a shredding device 30, the waste plastics are transported to the material determination separation device 20 after being crushed by the shredding device 30 to a predetermined size or smaller.

[0037] Fig. 2 is a schematic diagram showing a material determination separation device 20 used in this embodiment. As shown in Fig. 2, the material determination separation device 20 is configured to include a control unit 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 unit 26 having separation and collection trays 26a and 26b.

[0038] In the material determination separation device 20 as a material determination separation means, a control unit 21 controls the elements of each unit of the material determination separation device 20. That is, the control unit 21 controls a conveyor 22, a near-infrared sensor 23, and a gas supply unit 24. Heavy waste plastics discharged from the gravity separation device 10 are carried into the material determination separation device 20.

[0039] The heavy waste plastics that have been brought in are transported by the conveyor 22 as the rollers 22a rotate. The near-infrared sensor 23 identifies the material of the waste plastics by irradiating the waste plastics on the conveyor 22 with 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.

[0040] Based on the input sensor information, the control unit 21 controls the gas supply unit 24 to perform an air jet, which injects gas A, such as air, from the gas injection unit 25 at a predetermined timing on the discharge side of the conveyor 22. This separates the waste plastics Sa and Sb of different materials. Specifically, waste plastics Sa, such as PET and PS, which have a low chlorine content, and waste plastics Sb, such as PE, PP, PVC, and PVCD, which have a high chlorine content, are separated and collected in the separation and collection trays 26a and 26b, respectively. This separates the waste plastics Sa and Sb into low-chlorine-content waste plastics Sa and high-chlorine-content waste plastics Sb, which become residue. PE, PP, and PVC may also be separated and collected based on their material properties.

[0041] Here, the recovery rate of the low-content waste plastic Sa is, for example, about 15% of 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 Figure 1, the low-content waste plastic Sa can be recycled by chemical recycling, in which the composition is converted by chemical reaction before recycling, or by material recycling as described above.

[0042] On the other hand, the recovery rate of high-content waste plastic Sb recovered as residue is about 15% (30-15=), and the chlorine content increases to 4%, about four times the initial amount. In other words, in the plastic separation system 1, about 15% of the amount of waste plastic introduced becomes residue and is used for thermal recycling, etc.

[0043] According to the embodiment described above, the plastic separation system 1 is configured with a material determination separation device 20 located downstream of the specific gravity separation device 10, and further, a crushing and processing device 30 is provided upstream of the specific gravity separation device 10 and the material determination separation device 20, thereby making it possible to recover waste plastic with a reduced chlorine content.

[0044] 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 concept 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 that appropriately combine the components of the above-described embodiments and modifications. Furthermore, further effects and modifications can be easily derived by those skilled in the art. The broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Therefore, various modifications are possible without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

[0045] For example, in the above-described embodiment, the chlorine content of the waste plastic fed into the plastic separation system 1 and the separation ratio in the specific gravity separation device 10 and the material determination separation device 20 are merely examples, and can take various values ​​depending on the properties of the waste plastic.

[0046] In addition, in the embodiment described above, the crushing device 30 is placed before the gravity separator 10, but it is also possible to place the crushing device 30 after the gravity separator 10 and before the material determination separator 20, i.e., between the gravity separator 10 and the material determination separator 20.

[0047] In the embodiment described above, the gravity separator 10 separates the waste plastics into two types, light waste plastics and heavy waste plastics, but the number of types is not limited to two and the waste plastics may be three or more. In this case, the waste plastics fed into the material determination separator 20 at the subsequent stage can be the waste plastics with the highest specific gravity.

[0048] In the embodiment described above, the material determination separation device 20 separates the heavy waste plastics into two types: low chlorine content waste plastic Sa and high chlorine content waste plastic Sb, which will become residue. However, it is also possible to separate the heavy waste plastics into three or more types. Of the three or more types of separated waste plastics, the waste plastic with the highest chlorine content can be left as residue, and the waste plastic with the lowest chlorine content can be used for chemical recycling or material recycling. [Explanation of symbols]

[0049] 1. Plastic Separation System 10 Specific gravity separator 20 Material determination separation device 21 Control section 22 Conveyor 22a Laura 23 Near-infrared sensor 24 Gas supply section 25 Gas injection section 26 Recovery Department 26a, 26b Separate collection tray 30 Crushing and Processing Equipment A gas L Near infrared Sa,Sb Waste plastic

Claims

1. A plastic separation system configured to be able to separate multiple types of plastics, including plastics that use chlorine-based polyolefins, into predetermined classifications, a specific gravity separation means configured to be able to separate the plastics according to their specific gravity; a material determination and separation means provided downstream of the specific gravity separation means along the direction of conveyance of the plastics, and configured to separate the plastics according to their materials; a crushing means provided upstream of the material determination and separation means and configured to be able to crush the plastic; Equipped with The specific gravity separation means separates the plastics into two types: polyethylene and polypropylene, which are light substances having a specific gravity less than a predetermined value; and polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polystyrene, polyethylene containing chlorine-based polyolefins, and polypropylene containing chlorine-based polyolefins, which are heavy substances having a specific gravity equal to or greater than the predetermined value. The material determination and separation means determines the material of the heavy materials using near-infrared rays and separates the heavy materials into two types: polyethylene terephthalate and polystyrene, and polyethylene containing polyvinyl chloride, polyvinylidene chloride, or chlorine-based polyolefins, and polypropylene containing chlorine-based polyolefins. Plastic separation system.

2. The crushing means is configured to crush the plastic into crushed particles of 100 mm or less after crushing.

10. The plastic separation system of claim 1.

3. The gravity separation means is configured to be capable of performing sink-float gravity separation using water as a medium.

3. The plastic separation system of claim 1 or claim 2.

4. A plastic separation method for separating multiple types of plastics, including plastics containing chlorine-based polyolefins, into predetermined classifications, comprising: a gravity separation step of separating the plastics according to their specific gravity; a material determination step of separating the plastics separated by the specific gravity separation step according to the material of the plastics; a crushing process step of crushing the plastic before the material determination process; Including, In the gravity separation step, the plastics are separated into two types: polyethylene and polypropylene, which are light substances having a specific gravity less than a predetermined value; and polyvinyl chloride, polyvinylidene chloride, polyethylene terephthalate, polystyrene, polyethylene containing chlorine-based polyolefins, and polypropylene containing chlorine-based polyolefins, which are heavy substances having a specific gravity equal to or greater than the predetermined value. In the material determination step, the material of the heavy materials is determined using near-infrared rays, and the heavy materials are separated into two types: polyethylene terephthalate and polystyrene, and polyethylene containing polyvinyl chloride, polyvinylidene chloride, and chlorine-based polyolefins, and polypropylene containing chlorine-based polyolefins. Plastic separation methods.

5. The predetermined value in the gravity separation step is 1. The method for separating plastics according to claim 4.

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