JP2000246735A - Method and apparatus for separating waste plastics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the rate of recycling operation by providing a liquid gravity separator suitably adapted to the fraction of general waste matter plastics. SOLUTION: This apparatus comprises a means for crushing 12 and classifying 13 on material consisting principally of plastics of two or more kinds of different gravities in predetermined grain ranges, a first gravity separation means 18 for conveying plastics and making rough separation per kinds of material through gravity difference, a second gravity separation means 22 for separating lightweight side plastics separated by the first gravity separation means per kinds of material utilizing gravity difference again, means 23, 24 for separating the plastics fractionated separated per kinds of material and medium liquid, and a means 27 for permitting the liquid medium to be circulated to blending means 15, 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the treatment of waste plastic, and more particularly to an apparatus and a method suitable for treating waste plastic to obtain highly recyclable waste plastic.

[0002]

2. Description of the Related Art Non-combustible waste, especially plastic waste, includes industrial waste discharged in various industries and distribution processes, and general waste discharged at home. In particular, general waste is difficult to recycle because of its various shapes and compositions, contamination with foreign matter, and dirt, and it is customary to landfill. In recent years, the space of landfills has been drastically reduced, and there is an increasing demand for extending the life of the landfills and reducing the amount of waste plastic that occupies most of the landfills. For this reason, recycling of waste plastic has been studied from the viewpoint of environmental protection and resource recovery, and an apparatus for that purpose has been proposed.

FIG. 6 shows an example of a flow relating to the reuse of waste plastic.

[0004] Sorted waste plastics 1 have various compositions depending on the sorting ability of consumers or the policy of the local government from which they are collected. For example, sorting waste plastic 1 is mostly sheet,
Containers and packaging such as bags, trays, cups, and bottles. Small amounts of metals, glass bottles, pottery, paper, and other combustible materials that are unintentionally mixed during consumer separation.
The following explanation is made on synthetic debris, fragments of stationery, toys, small household appliances, and foreign matter such as food residue adhering to them.

[0005] Sorted waste plastics 1 are manually sorted 2 in advance by metals other than waste plastics, glass, paper and P.
Remove identifiable plastics such as ET. The selected waste plastic is coarsely crushed in crushing 3 and the foreign matter that has been overlooked in manual sorting 2 is separated in foreign matter separation 4 such as wind separation.
If necessary, secondary crushing 5 is performed, followed by washing and specific gravity separation 6.

In the washing / specific gravity separation 6, sewage water at the time of washing is subjected to wastewater treatment, and sediment having a relatively high specific gravity such as PET or PVC is discarded.

[0007] Waste plastics such as PO and PS7 having relatively light specific gravity are dewatered 8, dried 9 and melted / formed 10 in the next step.
Through the steps described above, a recycled product 11 is obtained.

As described above, it is possible to take out dechlorinated plastics such as PO and PS from which the chlorine content is removed, such as PVC and food residue.

On the other hand, as a conventional example of the liquid specific gravity separator,
Japanese Patent Application Laid-Open No. 09-193154 discloses a method of recycling a resin by continuously separating a resin mixture in which two or more materials are mixed at a high purity and a high recovery rate. Low.

[0010]

As a device for recovering dechlorinated substances in waste plastics, various basic devices such as crushing, foreign matter separation such as air separation, secondary crushing, washing and specific gravity separation, etc. are used. The necessity of the constituent means has been known as a principle of recovery.

On the other hand, it has been conventionally known to combine liquid specific gravity separators in multiple stages in order to improve the separation accuracy of dechlorinated plastics such as PO and PS, and to separate three or more types of mixed resins. I'm going.

However, in order to separate general waste plastics, a suitable combination or number of stages of the liquid specific gravity separator,
Or, it was at a stage where consideration was not given to the difference.

An object of the present invention is to provide a liquid specific gravity separator suitable for separating general waste plastics and to improve the recycling rate.

[0014]

[Means for Solving the Problems] A means for crushing and classifying a member mainly composed of two or more kinds of plastics having different specific gravities into a predetermined particle size range, and a means for transferring plastic and utilizing a difference in specific gravity A first specific gravity separation means for roughly separating each material, a second specific gravity separation means for separating the light-weight plastic separated by the first specific gravity separation means for each material again using the specific gravity difference, This can be achieved by a means for separating the medium liquid and the plastic separated for each material, and a means for circulating the medium liquid to the mixing means.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is an example of a flow of a waste plastic sorting apparatus according to an embodiment of the present invention.

Most of the waste plastics 100 are containers and packages such as sheets, bags, trays, cups, bottles, etc., and a small amount of metals, glass bottles, pottery, paper, etc., unknowingly mixed during consumer separation. Manual sorting, coarse crushing and foreign matter separation of general waste plastics, which are difficult to sort, and are mixed with foreign substances such as rubber, synthetic debris, pieces of stationery, toys, small household appliances and food residue adhering to them. Hereinafter, the operation of the present embodiment will be described after the above operation.

A classifier 13, a supply device 14, and a first mixing tank 15 are connected downstream of the crusher 12. First mixing tank 1
5 is provided with a first stirrer 16 and the first mixed liquid pump 1 is provided.
7 to a first liquid specific gravity separator 18. The first liquid specific gravity separator 18 is composed of an inlet pipe, a separator body (cylinder part + cone part), an upper discharge pipe, a lower discharge pipe, and a sealing part. The upper discharge pipe is provided in the second mixing tank 19 and the lower discharge pipe. Leads to the dehydrator 24. The second mixing tank 19 is provided with a second stirrer 20, which is connected to a second liquid specific gravity separator 22 via a second liquid mixture pump 21. In this embodiment, an example in which the second mixing tank 19 is provided is described.
9 (including the second stirrer 20), and directly to the second liquid specific gravity separator 22 by the second mixed liquid pump 21, the second mixing tank 19 (including the second stirrer 20), the second mixed liquid It is also conceivable that the liquid is sent directly to the second liquid specific gravity separator 22 without providing the pump 21.

The second liquid specific gravity separator 22 is composed of the same components as the first liquid specific gravity separator 18, and the upper discharge pipe is connected to the dehydrator 23 and the lower discharge pipe is connected to the dehydrator 24. Dehydrator 2
3 and 24 are connected to the circulating water tank 27 and the wastewater treatment device 2
8, the first, second via the first and second transfer pumps 29, 30
Return to the second mixing tanks 15 and 19.

The main structural differences between the first and second liquid specific gravity separators are as follows.

(1) The diameter of the lower discharge pipe at the bottom of the liquid specific gravity separator is second ≧ first.

(2) The gap between the bottom of the liquid specific gravity separator and the lower end face of the upper discharge pipe (hereinafter referred to as the bottom gap) is second ≧ first.

The reason is that the diameter of the lower discharge pipe and the gap at the bottom of the first liquid specific gravity separator are made relatively small, so that only foreign matters (metal, glass, ceramics, stones, etc.) and high specific gravity components of plastic are discharged downward. It is intended to do so. Also,
The reason why the diameter of the lower discharge pipe and the gap at the bottom of the second liquid gravity separator are made relatively large is to discharge the high specific gravity component, thread, cotton, cloth, paper, etc. of the plastic spilled by the first liquid gravity separator downward. It is intended. Further, the present embodiment is intended to improve the recyclability of the upper collection and to minimize the power and the number of parts. Therefore, it is considered that the combination of three or more liquid specific gravity separators contributes to the improvement of the quality, but the reduction of the recycling rate and the increase in the number of power and parts are not considered to be industrially useful.

Next, the flow of the waste plastic 100 is as follows.

The waste plastic 100 is pulverized by the pulverizer 12 to such a particle size as to peel off for each single material. In the mixture of the pulverized resins, fine dust, fibrous material, foamed resin 101 and the like, which have been excessively pulverized by the classifier 13, are removed, and the other mixed plastics 102 are supplied to the first mixing tank 15 by the supply device 14. Supplied to The first mixing tank 15 is provided with a first stirrer, which stirs the liquid medium 103 and the mixed plastic 102 uniformly, removes air bubbles adhering to the resin surface, Liquid specific gravity separator 18
Liquid. The inlet pipe of the first liquid specific gravity separator 18 is attached tangentially to the separator main body (tube portion), and the mixed liquid spirals in the separator, and the heavy resin is separated by the centrifugal force into the separator wall. The light-weight resin with small centrifugal force gathers at the center of the separator. While the heavy resin descends along the separator wall, the first heavy resin (high specific gravity component of plastic, metal, glass, pottery,
It is supplied to the dehydrator 24 as foreign matter 106 such as paper and cloth containing stone and water. The lightweight resin is supplied to the first lightweight resin 10 together with the liquid medium from an upper discharge pipe attached to the center of the separator.
Discharged as 5. At this time, the recovered amount of the first lightweight resin is 70% or more of the waste plastic 1, preferably 75% to 9%.
Adjust the first liquid specific gravity separator to 5%. The first lightweight resin 105 is supplied to the liquid medium 1 by the second stirrer in the second mixing tank 15.
07, the bubbles adhering to the resin surface are more efficiently removed, and are sent to the second liquid specific gravity separator 22 by the second liquid mixture pump 21. In the second liquid specific gravity separator 22, the second heavy resin 109 and the second lightweight resin 108 are discharged from the lower discharge pipe together with the liquid medium in the same operation as the first liquid specific gravity separator 18, and the second lightweight resin 108 is discharged. The resin 109 is supplied to the dehydrator 24 similarly to the first weight resin 106, and the second lightweight resin 108 is supplied to the dehydrator 23.
The content of the second weight resin 109 is composed of the high specific gravity component of the plastic spilled by the first liquid specific gravity separator, thread, cotton,
The contents of the second lightweight resin 108, such as cloth and paper, are plastic, low specific gravity components such as PO and PS, and part of yarn, cotton, cloth and paper.

The liquid medium 11 dehydrated by the dehydrators 23 and 24
2 is stored in the circulating water tank 27 and the lightweight resin 110 after dehydration and the heavy resin 111 after dehydration
Collected at 5,26. The liquid medium stored in the circulating water tank 27 is separated into first and second specific gravity separators 18 by a wastewater treatment facility 28.
Inorganic salts, dirt, food residue, and the like, which have been washed away by the washing effect of 22, are removed, and the clean liquid medium 113 is passed through the first and second transfer pumps 29 and 30, and the first and second mixing tanks 15 and
Return to 19. According to the embodiment of the present invention, by separating general waste plastics in a two-stage liquid specific gravity separator, the processed material is suspended in water, threads and cotton dust are loosened, and accompanying plastic is reduced. Bubbles on the plastic surface are easily removed, and the separation performance is improved. In addition, an increase in the number of washing steps reduces inorganic salts, dirt, food residue, and the like, and improves the quality as a recycled material.

Also, the present embodiment is directed to improving the recyclability of the upper collected material, and is an invention in which the upper collected material of the first liquid specific gravity separator is separated again by the second specific gravity separator. In order to improve the single material purity of the components,
When the recovered material below the first liquid specific gravity separator is separated again by the second specific gravity separator, if the relationship between the bottom gap of the first and second liquid specific gravity separators and the diameter of the lower discharge pipe is reversed, the same as in the above embodiment. It can be implemented similarly.

Further, in order to improve the purity of the low and high specific gravity components, it is also possible to separate the upper and lower recovered materials of the first liquid specific gravity separator with separate second specific gravity separators.

FIG. 2 shows an example of a structure around an upper discharge pipe according to an embodiment of the present invention. Liquid specific gravity separator 1
A seal ring 34 such as an O-ring is provided on the seal surface of a seal receiving flange 32 fixed to the main body of the main body 8 and the seal holding flange 33 is fastened with bolts or the like, so that the upper discharge pipe 31 arranged at the center of the flange is provided. Is fixed. As a result, the upper discharge pipe can be continuously moved and set up and down, an arbitrary bottom gap can be obtained, operability is improved, and it is possible to cope with various waste plastics.

FIG. 3 shows an example of a peripheral structure of the lower discharge pipe according to the embodiment of the present invention. Liquid specific gravity separator 1
8 is provided with a flange below the cone portion 35, and a wide-mouth discharge pipe 36 (FIG. 4) or a narrow-mouth discharge pipe 37 is provided on the flange.
(Fig. 5) Alternatively, by attaching discharge pipes with different discharge diameters, it is possible to easily change the specifications of the first and second liquid specific gravity separators, and to obtain an arbitrary lower discharge pipe diameter.
Operability is improved, and it is possible to handle a wide variety of waste plastics.

[0030]

According to the embodiment of the present invention, by separating general waste plastics by a two-stage liquid specific gravity separator, the processed material is suspended in water, threads and cotton waste are loosened, and the accompanying plastic is removed. And the bubbles on the plastic surface are easily removed, and the separation performance is improved. In addition, with the increase in the number of washing steps, inorganic salts,
It has the effect of reducing dirt, food residue, etc., and improving the quality of recycled materials. In addition, by adjusting the bottom gap and the diameter of the lower discharge pipe, the operability is improved, and it is possible to handle a wide variety of waste plastics.

[Brief description of the drawings]

FIG. 1 is a flowchart showing one embodiment of a waste plastic sorting apparatus according to the present invention.

FIG. 2 is a structural diagram showing an example of a peripheral structure of an upper discharge pipe used in the embodiment shown in FIG.

FIG. 3 is a sectional structural view showing an example of a lower discharge pipe used in the embodiment shown in FIG.

FIG. 4 is a sectional structural view showing an example of a wide-mouth discharge pipe connected to the lower discharge pipe shown in FIG. 3;

FIG. 5 is a sectional structural view showing an example of a narrow-mouth discharge pipe coupled to the lower discharge pipe shown in FIG. 3;

FIG. 6 is a flowchart showing an example of a conventionally proposed waste plastic recycling system.

[Explanation of symbols]

12 ... crusher, 13 ... classifier, 14 ... supply device, 15 ...
First mixing tank, 16: first stirrer, 17: first mixed liquid pump, 18: first liquid specific gravity separator, 19: second mixing tank, 2
0: second stirrer, 21: second liquid mixture pump, 22: second liquid specific gravity separator, 23, 24 ... dehydrator, 25, 26 ... collection vessel, 27 ... circulating water tank, 28 ... waste water treatment device, 29 …
First transfer pump, 30 ... second transfer pump.

Continued on the front page (72) Inventor: Osamu Kita 794, Higashi-Toyoi, Katsumatsu-shi, Yamaguchi Prefecture Inside the Kasado Plant, Hitachi, Ltd. (72) Inventor: Takanobu Ono 794, Higashi-Toyoi, Kazamatsu-shi, Yamaguchi Prefecture Hitachi Techno Engineering Co., Ltd. 4D071 AA41 AA52 AB14 AB15 AB23 AB25 AB43 CA01 CA05 DA15 4F301 AA11 AA21 AD06 BD05 BF09 BF12

Claims (8)

[Claims] 1. A means for crushing and classifying a mixing member mainly composed of plastics having different specific gravities into a predetermined particle size range, and a first means for transferring plastics and roughly separating each material by utilizing a difference in specific gravity. A specific gravity separating means, a second specific gravity separating means for separating the light-weight plastic separated by the first specific gravity separating means for each material again using the specific gravity difference, and a plastic separated for each material. An apparatus for separating waste plastic, comprising: means for separating a medium liquid; and means for circulating the medium liquid to a mixing means. 2. A waste liquid separating apparatus according to claim 1, wherein the means for separating the plastics for each material by utilizing a difference in specific gravity is a liquid specific gravity separator for separating the liquid by centrifugal force of the liquid. Plastic sorting equipment. 3. The specific gravity of the medium liquid of the means for supplying and mixing the crushed pieces having a predetermined particle size into the medium liquid according to claim 1 is a specific gravity between a plastic having a high specific gravity and a plastic having a low specific gravity. Is a waste plastic separation device characterized by using an aqueous medium (specific gravity: 1.0). 4. The liquid specific gravity separator according to claim 2, wherein
An upper discharge pipe for discharging plastic with a low specific gravity is swingably inserted vertically so that the gap between the bottom of the liquid specific gravity separator and the lower end face of the upper discharge pipe can be changed continuously. Sorting device. 5. The liquid specific gravity separator according to claim 2, wherein
The diameter of the discharge pipe at the bottom of the liquid specific gravity separator can be changed, and the discharge pipe diameter of the second specific gravity separation means of claim 1 is equal to or greater than the discharge pipe diameter of the first specific gravity separation means. Waste plastic sorting equipment. 6. A step of crushing and classifying a member mainly composed of plastics of different materials into a predetermined particle size range, and a first specific gravity separation for transporting the plastic and roughly separating each material using a difference in specific gravity. A second specific gravity separation step in which the light-weight plastic separated in the specific gravity separation step is separated again for each material using the specific gravity difference, and a plastic and medium liquid separated for each material are separated. A method for separating waste plastic, comprising a step of separating and a step of circulating a medium liquid to a mixing step. 7. The method for separating waste plastics according to claim 6, wherein in the first specific gravity separation step, the recovered amount of the plastic having a low specific gravity is 70% or more of the waste plastic raw material. 8. The amount of recovered plastic having a low specific gravity according to claim 7, preferably from 75% to 9% of the waste plastic raw material.
A method for separating waste plastic, characterized in that it is set to 5%.