JP2004255572A - Recycling treatment method for waste plastics - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recycling treatment method for waste plastics improved in material sorting precision and productivity by taking in manual work and an automatic material sorting process, increasing the recovery rate of a recycled raw material becoming a molding material and capable of avoiding the admixture with a different kind of a material (e.g., a composite plastic, a rubber in a bag or the like) obstructing the enhancement of purity originating from the interior of a bag, or the like. <P>SOLUTION: A mixture comprising many kinds of waste plastics received in facilities is separated into respective plastic materials clear in material quality and foreign matter by manual work in a manual sorting process before sampled. Various plastic materials not sampled by manual sorting are sorted for every material quality in an automatic material sorting process after separated into a container type heavy material and a packaging type light material in a wind force sorting process. The sorted plastic material is used along with the sampled plastic material clearly discriminated and manually sorted for every material quality to form a molding material. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a waste plastic recycling method for separating waste plastic collected as domestic waste, industrial waste, and the like so that the plastic can be easily reused.
[0002]
[Prior art]
From the viewpoint of resource saving and with the enforcement of the Container Recycling Law, a number of waste plastic recycling methods have been proposed. The collected waste plastic is often mixed with garbage bags, plastic bottles, trays, and the like, and also contains foreign matters such as paper, metal, and sand. Recycling into a new product is performed as a recycled product that can be formed into granules or flakes by dividing it into different materials, so the elemental technology of the recycling process is to remove foreign substances from waste plastic and separate them by type In order to do so, many proposals for such sorting techniques have been made.
[0003]
The first method of the separation treatment is based on specific gravity. Japanese Patent Application Laid-Open No. 11-34056 discloses that air bubbles are generated in a separation tank and stirring is performed. Has proposed to separate waste plastics by specific gravity by installing a central obstacle in a hydrocyclone, and these are particularly effective in separating polystyrene (PS) whose specific gravity is slightly larger than water. Is done.
[0004]
Furthermore, a dry processing method of crushing waste plastic including a band-shaped film such as a tape and removing and separating metal is also proposed. As a method of sorting each material, JP 2000-334390A discloses a method of treating a material on a conveyor. It is proposed to arrange a material identification device and selectively discharge the air according to the identified material by air blown from an air nozzle.
[0005]
However, according to the waste plastic recycling method as described above, not only the equipment becomes excessively large and the cost increases, but also in the automatic material sorting process, the sorting method is not adapted to the shape characteristics of the plastic waste. Therefore, the identification accuracy was poor and the productivity was low.
[0006]
Japanese Patent Application Laid-Open No. 2002-317071 describes a recycling treatment method in which recycled materials are manually separated for granulation and miscellaneous plastics for oiling are separated. In this case, the identification accuracy is manually determined. However, since the amount of waste plastic that cannot be collected by manual selection is large in practice, the recovery rate of recycled raw materials used as molding materials was not good. That is, it was lacking in considering the characteristics of the plastic waste composed of a plurality of materials.
[0007]
In addition, in the case of waste plastic materials of bags such as confectionery bags, there are cases where residues and foreign substances remain in the bags. The combination of the identification device and the crusher alone causes the residues to be mixed into the recycled product, and waste plastic materials to be removed. For this reason, the quality of waste plastic after separation was not sufficient.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned circumstances, and by incorporating manual work and an automatic material selection process, the material selection accuracy and productivity are improved, and the recovery rate of the recycled material as the molding material is increased. It is an object of the present invention to provide a method of recycling waste plastic that can avoid mixing of foreign materials (for example, composite plastic, rubber in a bag, and the like) that hinder the improvement of purity due to inside.
[0009]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention is to collect and collect various kinds of waste plastic received in the facility by manually separating each plastic material having a clear material and foreign matter in a manual sorting process, and removing the plastic from the collection. After that, miscellaneous plastic materials other than hand-sorting are separated into heavy materials container system and light materials packaging system by the wind sorting process, then separated by material in the automatic material sorting process, and then collected. It is intended to provide a method of recycling waste plastic, which comprises producing a material for molding together with a separated product for each material of a plastic material which has been clearly identified on the side of the plastic material.
[0010]
In addition, for materials other than manually selected products, after sorting through each material through the automatic material sorting process, finely crushing in the crushing process, washing in the washing and dewatering process, and then mixing in the wet specific gravity sorting process More preferably, the object of the present invention can be achieved by removing and feeding to a granulation step for producing a material for molding.
[0011]
[Action]
According to the above configuration, the following operation is exhibited.
[0012]
(1) In the manual sorting process, plastic waste of a clear material that can be easily identified by its appearance is performed by human work. Therefore, waste plastic of each material of PE, PP, PS, and EPS is produced with high precision and low cost. Can be separated.
[0013]
{Circle around (2)} By sorting into a container system for heavy materials and a packaging system for light materials by the wind separation process, conditions for the automatic material selection process according to the shape characteristics are set. Specifically, the container-based plastic has a large apparent specific gravity, so that the influence of wind force due to the speed of the conveyor is small, and the speed of the belt can be increased, so that productivity is improved. Further, conventionally, when the discharging method in the automatic material selection step is compressed air, it is necessary to adjust the amount, pressure, and direction of the compressed air due to a difference in apparent specific gravity. Separating the two materials with the packaging system makes such adjustments unnecessary.
[0014]
{Circle around (3)} Since the container material is supplied to the automatic material selection process (for example, an NIR sorter) via the container flattening process, a round shape such as a PET bottle is flattened by this process. Therefore, the sheet can be stably conveyed without rolling on the conveyor, and the identification accuracy is increased, so that the productivity is improved.
[0015]
In addition, in the manual sorting process, waste plastics of various types received in the facility are collected by hand in separate plastic materials and foreign materials, and for miscellaneous plastic materials other than hand-selected materials that are not collected, After that, it was separated into a container system for heavy materials and a packaging system for light materials by the wind sorting process, and then separated for each material in the automatic material sorting process. If a material for molding is produced together with a separated product for each material of the plastic material, it is more effective to achieve the object as described later.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, as described above, a special process is performed on hand-selected products that can be distinguished in the hand-selecting process 3 and those other than those that are relatively difficult to separate in terms of material. In this process, it is desirable that in the process, the container-based material other than the hand-selected product is subjected to the container flattening process 6 and then to the automatic material sorting process 7.
[0017]
Further, it is desirable that the materials other than the hand-selected products be as described in claim 2. That is, after crushing, for example, from several millimeters to several tens of millimeters in the crushing step 8, washing is performed in the washing and dewatering step 9, and in the wet specific gravity sorting step 10, mixed foreign materials (such as PVC materials) are removed. This is particularly effective as a means for preventing a mistake that a waste plastic material composed of a plurality of materials is identified by a specific material in spite of the fact that the waste plastic material includes a dissimilar material in the automatic material selection process 7. It is valid. Specifically, PVC is removed by putting and agitating crushed pieces into a water tank, utilizing the property that the specific gravity is particularly large as compared with other plastic materials and that the material sinks in water. Therefore, according to the invention described in the same paragraph, it is particularly effective in improving the purity of the recycled product and preventing the contamination of the PVC material containing chlorine.
[0018]
The types of plastic shown here are reference examples, and if similar means are used, any number of types can be separated. Incidentally, waste plastics include various plastics such as PE (polyethylene), PP (polypropylene), PS (polystyrene), PVC (polyvinyl chloride), PET (polyethylene terephthalate), EPS (foamed styrene), and the like. .
[0019]
【The invention's effect】
As described above, according to the present invention, since the identification accuracy is improved by rationally combining the manual work and the mechanical work, a highly pure recycled product can be provided, and the productivity can be improved. As a result, it is possible to provide an inexpensive recycled material since the recovery rate of the recycled material used as a molding material is increased.
[0020]
【Example】
Next, embodiments will be described with reference to the drawings, but it goes without saying that the present invention is not limited to the following embodiments.
[0021]
(1) The mixed plastic waste received in the facility is crushed by the crusher 1 after the garbage bag or the like is broken or the compressed plastic is loosened. Feed to Step 3 (FIG. 1).
[0022]
{Circle around (2)} In the hand sorting step 3, as shown in FIG. 2, the waste plastic placed on the conveyor is manually selected and transferred to the bunker. Unknown miscellaneous waste plastics, such as bags, plastic bottles, trays, etc., go through another processing path Pa as products other than hand-selected products. Note that the paper and foreign matter are carried out as discarded products for disposal (chain arrows in FIG. 1).
[0023]
{Circle around (3)} Those other than the manual sorting are supplied to the automatic sorting equipment (arrow Pa, FIG. 3), where the metal is first removed by the eddy current sorting step 4, and then the vessel system (heavy load) is sorted by the wind sorting step 5. Material) and packaging system (light material) (arrows Q, R). Then, the container material passes through a container flattening process 6 (arrow Q). Both the container system and the packaging system are sent to the automatic material sorting process 7 (NIR sorting machine) (arrows Q and R), where they are separated into, for example, PET, PE / PP and other products, for example, PS. It is sent to the volume reduction / storage facility 20. Before that, the PE / PP is again subjected to the automatic material sorting step 7.
[0024]
(4) The separated packaging PE / PP, packaging PE (manual selection), container PE / PP, and container PS pass through the volume reduction / storage facility 20 and then to the crushing / washing facility (FIG. 4). After being crushed to several millimeters in the crushing step 8, it is washed in the washing and dewatering step 9, and vinyl chloride (PVC) and sand are removed in the wet specific gravity sorting step 10, and is further washed in the washing and dewatering step 11. Then, it is supplied to the granulation step 12. The PS is sent to the product storage yard through the washing and dewatering step 11.
[0025]
{Circle around (5)} Container PET (hand sorting), packaging PET and EPS (hand sorting) (arrow Pb in FIG. 1) are crushed in a crushing step 14 after a washing step 13 as shown in FIG. Then, it is washed again in the washing / dehydrating step 15 and supplied to the granulating step 12.
In the granulation step 12, the material is granulated into predetermined granules, or is made into flakes as they are to produce material recycled products (pellets, flakes).
[Brief description of the drawings]
FIG. 1 is a flowchart showing the entire process of a waste plastic recycling method as an example of the present invention.
FIG. 2 is a flowchart showing a flow of a product other than a hand-selected product in the hand-selecting process of FIG. 1;
FIG. 3 is a flowchart showing the flow of products other than hand-selected products in the automatic sorting equipment of FIG. 1;
FIG. 4 is a flowchart showing a flow of items other than hand sorting in the crushing / washing equipment of FIG. 1;
FIG. 5 is a flowchart showing a flow of hand-selected products in the crushing / washing equipment of FIG. 1;
[Explanation of symbols]
3 Hand sorting process 4 Eddy current sorting process 5 Wind sorting process 6 Container flattening process 7 Automatic material sorting process 8 Crushing process 9 Washing and dewatering process 10 Wet specific gravity sorting process 12 Granulation process 13 Washing process 14 Crushing process 15 Washing and dewatering process

Claims (2)

In the manual sorting process, the mixed plastic waste received in the facility is manually separated and collected into each plastic material with clear material and foreign matter. Separation into heavy material container system and light material packaging system by wind sorting process, then sorting by material in automatic material sorting process, while hand-sorted plastic material with clear identification of the sampled side A method for recycling waste plastics, wherein a material for molding is produced together with a separated product for each material. For materials other than hand-sorted products, after sorting through each material through the automatic material sorting process, finely crushing in the crushing process, washing in the washing and dewatering process, and then removing mixed foreign materials in the wet specific gravity sorting process 2. The method according to claim 1, wherein the waste plastic is supplied to a granulation step for producing a material for molding.

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