JP5964066B2 - Recycling method for mixed waste plastic - Google Patents

Description

  The present invention relates to a method for recycling mixed waste plastic containing polystyrene foam and other plastics, and more particularly, to a method for recycling mixed waste plastic with high purity and high recycling efficiency.

Conventionally, various types of plastic are mixed in waste plastic discharged from households and business establishments as waste. Examples of this include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and the like.
When such waste plastics are separated to produce recycled plastics, it is difficult to completely separate finely pulverized waste plastics and various types of waste plastics that are in close contact with moisture. As a result, there was a problem that the purity of the finished recycled plastic was low (see FIG. 2, Table 3 Conventional Example 1). In addition, since the waste plastic that is difficult to sort out must be discarded, the amount of regeneration (yield) decreases (see FIG. 3, Table 3 Conventional Example 2). That is, there is a problem that the recycling efficiency of recycled plastic is low. Therefore, in order to solve such problems, in recent years, techniques for improving purity and increasing the amount of regeneration have been developed, and several inventions have already been disclosed in this regard.

Patent Document 1 discloses a mixed waste plastic regeneration processing method and a mixed waste plastic regeneration processing apparatus capable of producing a high-purity recycled plastic by screening and the like under the name “mixed waste plastic regeneration processing method and mixed waste plastic regeneration processing apparatus”. An invention related to this is disclosed.
Hereinafter, the invention disclosed in Patent Document 1 will be described. The invention disclosed in Patent Document 1 includes a crushing step of crushing mixed waste plastic mixed with polystyrene foam and other plastics, and placing the crushed mixed waste plastic into a stirred water tank, and floating the foam while collecting the foamed polystyrene in a predetermined place. There are two types according to the particle size: sorting process, recovery process for collecting foamed polystyrene and other plastics attached to the foamed polystyrene, grinding process for grinding the collected foamed polystyrene and other plastics, and crushed foamed polystyrene and other plastics. And a sieve sorting step for sorting as described above.
The present invention will be described with reference to FIG.
In FIG. 4, the polystyrene foam and other plastics collected in the collecting step 104 are washed and dehydrated in the washing and dehydrating step 110 and crushed in the pulverizing step 111. In the pulverization step 111, the polystyrene foam has a small particle diameter, and polyethylene and polypropylene have a larger particle diameter than the polystyrene foam. In the next sieve selection step 112, small polystyrene foam (small 30), medium polystyrene foam and polyethylene, polypropylene, etc. (medium 20), large polyethylene, polypropylene, etc. (large 10) are separated. The small 30 is regenerated as recycled plastic (B), and the middle 20 and large 10 are re-introduced into the levitation sorting process 103.
The mixed waste plastic regeneration processing method and the mixed waste plastic regeneration processing apparatus having such characteristics have an effect that the polystyrene foam having a small particle size is selected by the sieve selection step. Accordingly, it is possible to obtain a recycled plastic with high purity polystyrene. In addition, the polystyrene foam referred to in this document is polystyrene.

Next, Patent Document 2 describes the recycling of a plastic mixture having a plurality of wind sorting processes and a plurality of wet processes under the name of “Recycling method of plastic mixture, and plastic raw material and plastic molded body”. An invention relating to a method for making it into the same is disclosed.
The invention disclosed in Patent Document 2 includes a crushing process for crushing a plastic mixture composed of a plurality of types of plastics, a plurality of wind sorting processes for sorting heavy and light objects by wind power, A plurality of wet processes exposed to a liquid atmosphere, and the wet process includes one or more wet specific gravity separation processes for selecting plastics by specific gravity using a liquid.
In the recycling method of the plastic mixture having such characteristics, foreign substances other than the collected plastic system can be easily and efficiently removed. Therefore, it is possible to obtain a high-quality plastic molded body that can be used for various applications from a plastic mixture composed of a plurality of types, and to reduce the amount of plastic waste.

Patent Document 3 discloses an invention relating to a compression dehydration drying apparatus for soft plastics under the name of “washed plastic compression dehydration drying apparatus”.
The invention disclosed in Patent Document 3 has a long cylindrical shape, a drum having a large number of drain holes on the bottom surface, a spiral rod mounted in the drum, and one end of the drum mounted to rotate the spiral rod. And a discharge port provided at the other end of the drum, and an input port provided on the side close to the drive device of the drum.
The compressed plastic dehydration drying apparatus having such characteristics has an action of evaporating moisture of the cleaned plastic by the heat generated by friction and discharging it from the ventilation holes. In addition, by heating the drum, it has the effect of quickly vaporizing and discharging the water in the washed plastic. Therefore, it has an effect that it is possible to dry soft plastic wastes such as washed thin films or bags that easily adhere to each other to an ideal level.

JP 2006-205664 A JP 2007-15340 A JP 2007-240110 A

  In the invention disclosed in Patent Document 1, some of the crushed polyethylene, polypropylene, etc. are sorted into a small particle size (small 30) in the sieve sorting step and mixed into the expanded polystyrene. There was a problem that the purity of the expanded polystyrene could be lowered. In addition, since sorting products other than the small particle size (medium 20 and large 10) are re-introduced into the flotation sorting process, there is a problem that the processing efficiency decreases.

  Next, in the invention disclosed in Patent Document 2, it is necessary to include at least a plurality of wind sorting processes and a plurality of wet processes, and the wet process includes one or more wet specific gravity separation processes. For this reason, the process is complicated and the cost may increase.

  And in the invention disclosed by patent document 3, since the temperature of a discharge | emission site | part is close to the melting temperature of a plastic, there exists a possibility that a plastic may melt partially and may mutually weld. Therefore, although the problem of water vaporization has been achieved, it is highly likely that it is difficult to use such a compression dehydration drying apparatus alone for the separation treatment of the mixed waste plastic.

  The present invention has been made in response to such a conventional situation, and improves the quality by increasing the purity of recycled plastic, and also improves the efficiency of processing and increases the amount of recycled plastic mixed waste. An object is to provide a reproduction processing method.

In order to achieve the above object, a method for reclaiming mixed waste plastic according to the invention described in claim 1 includes a crushing step of crushing the mixed waste plastic in the method for reclaiming mixed waste plastic containing foamed polystyrene and other plastics. , Put the crushed mixed waste plastic into the water tank, of which the compression dehydration process compresses and dehydrates the mixed waste plastic floating on the surface of the water, the crushing process crushes the compressed waste plastic mixed waste, and the crushed mixed waste blown plastic, and styrofoam the mixture waste plastics, and wind sorting step of sorting from the styrofoam lightweight said and other plastics, and the remaining mixed waste plastics from the water bath after removal of compressed dehydrated mixed waste plastics It was centrifuged centrifuged to remove the specific gravity of one or more polyvinyl chloride And a release step, characterized in that it comprises a recovery step of mixing a lightweight other plastic than polystyrene foam having been selected by the wind sorting step in mixing waste plastic and centrifuged.
In the mixed waste plastic recycling method having the above-described configuration, only the crushed mixed waste plastic that has floated on the water surface is compressed and dehydrated. Has the effect of As this plastic having strong buoyancy, for example, there is one in which polyethylene, polypropylene, or the like is adhered to foamed polystyrene.
Next, a plastic with strong buoyancy has the effect | action that the water | moisture content contained by compression is extruded and dehydrated. In compression with a constant pressure, the plastic having a higher water absorption capacity has more water remaining therein. In addition, the polystyrene foam contains bubbles in polystyrene and has a higher water absorption capacity than polyethylene, polypropylene, and the like.
Further, the dehydrated plastic is separated from the crushed plastic in the crushing step. A screw press dehydrator or the like is used for compression, and a blower blower or the like is used for crushing.
Subsequently, since the separated plastics have different moisture contents, they are sorted into those having a large moisture content (foamed polystyrene) and those having a small moisture content (polyethylene, polypropylene, etc.) by blowing.

Furthermore, in the mixed waste plastic recycling method having the above-mentioned configuration, the “remaining mixed waste plastic” means a mixed waste plastic other than the heavy waste and the mixed waste plastic floating on the water surface, and examples thereof include polyethylene and polypropylene. . The “other plastics lighter than the expanded polystyrene selected in the wind sorting process” refers to plastics (polyethylene, polypropylene, etc.) having a low water content among the separated plastics in the claims.
According to the centrifugation step of the present claim, among the remaining mixed waste plastic, plastic that can be used as recycled plastic is recovered.
Therefore, when the main components of the “remaining mixed waste plastic” and the “plastic with a low water content” coincide with each other, the recovery and the amount of regeneration are increased by the recovery process.

Process for regeneration of mixed waste plastics according to the invention of claim 2, wherein, in the process for regeneration of a mixed waste plastics according to claim 1 Symbol placement, compression dehydration step, and adjustable moisture content of the compressed dehydrated mixed waste plastics It is characterized by doing.
In the mixed waste plastic recycling method having the above configuration, “the water content of the mixed waste plastic can be adjusted” means that the amount of water extruded from the mixed waste plastic is controlled by controlling the compression. Here, when the compression is insufficient, the amount of water is excessive, and when the compression is excessive, it is not sufficiently crushed in the subsequent pulverization step, and in all cases, the degree of separation of the plastic is lowered. That is, the purity of the recycled plastic is reduced. Therefore, by adjusting the amount of water to be extruded by controlling the compression, the degree of separation of the mixed waste plastic is increased, and the purity of the recycled plastic is improved.

The method for reclaiming mixed waste plastic according to the invention described in claim 3 is the method for reclaiming mixed waste plastic according to claim 2, wherein the water content is 10 to 45%.
In the mixed waste plastic recycling method of the above configuration, when the dry weight of the plastic is a (g) and the weight of the plastic containing water is b (g), the moisture content (%) is (ba) / b. × 100.
By setting the water content of the mixed waste plastic to 10 to 45%, there is an effect that the purity of the recycled plastic is maintained at a high level. As an example, a polystyrene foam has a purity of 90% or more by weight.

The method for reclaiming mixed waste plastic according to claim 4 is the method for reclaiming mixed waste plastic according to any one of claims 1 to 3 , wherein the other plastic that is lighter than the foamed polystyrene is It is characterized by being polyethylene or polypropylene.
The method for recycling mixed waste plastic having the above-described configuration has an effect that the purity of the recycled polystyrene is improved. In addition, since the recycled foamed polystyrene mixed with polyethylene or polypropylene is usually discarded, the discarded amount is reduced, and not only the purity is improved but also the recycled amount is increased at the same time.

According to the method for reclaiming mixed waste plastic according to claim 1 of the present invention, it is possible to separate plastics having strong buoyancy from the mixed waste plastic. Furthermore, by compressing and dewatering, the water content of the plastic can be used as an index for separation, and can be led to the subsequent crushing process and wind sorting. And in these processes, it sorts for every moisture content, and the plastic which belongs to each can be collect | recovered. Therefore, it becomes possible to select plastics with strong buoyancy with higher accuracy, and the two problems of producing high-purity and highly recyclable recycled plastics can be solved simultaneously.
In addition, each process of this mixed waste plastic recycling process is a simple process that exerts physical effects such as crushing and compression dehydration, and does not include chemical processes such as chemical reaction and plastic melting, so it is complicated. And there is less risk of explosions.

Further, according to the process for regeneration of a mixed waste plastics according to claim 1 of the present invention, since the plastic is available among the remaining mixture waste plastic is recovered in high purity and regeneration amount, remaining mixture waste plastics This has the effect of reducing the waste rate.

According to the method for reclaiming mixed waste plastic according to claim 2 of the present invention, it is possible to adjust the amount of water to be extruded, so that the mixed waste plastic can be brought into an appropriate moisture content state. That is, since the degree of separation of the mixed waste plastic can be increased, it is possible to always produce high-purity recycled plastic.

According to the method for reclaiming mixed waste plastic according to claim 3 of the present invention, the purity is maintained at a desired high level only by controlling the water content, so that high-purity recycled plastic can be produced easily and reliably. can do.

According to the method for recycling mixed waste plastic according to claim 4 of the present invention, the waste that cannot be used in the mixed waste plastic is reduced, so that the recycling efficiency of the recycled plastic can be improved.

These are process drawings of the recycling processing method of the mixed waste plastic which concerns on an Example. These are process drawings of the regeneration processing method of the mixed waste plastic which concerns on the prior art example 1. FIG. These are process drawings of the recycling processing method of the mixed waste plastic which concerns on the prior art example 2. FIG. These are process drawings of the regeneration processing method of the mixed waste plastic which concerns on the prior art example 3. FIG.

The method for recycling mixed waste plastic according to the embodiment of the present invention will be described in detail with reference to FIG.
FIG. 1 is a process diagram of an example of a method for recycling a mixed waste plastic according to an embodiment of the present invention.

As shown in FIG. 1, the mixed waste plastic P1 regeneration processing method according to the present embodiment includes a foreign matter removing process at Step S1, a crushing process at Step S2, a floating sorting process at Step S3, a recovery process at Step S4, and Step S5. Washing step, step S6 compression dehydration step, step S7 crushing step, step S8 wind sorting step, step S9 drying step, step S10 volume reduction / granulation step, step S11 centrifugation step, step S12 The drying process of step S13, the recovery process of step S13, and the granulation process of step S14 are intended to obtain recycled plastics P4 and P6.
The mixed waste plastic P1 includes a seasoning container, an egg pack, a meat / vegetable tray, and the like. In this, polyethylene (PE), polypropylene (PP), polystyrene foam (polystyrene, PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC) and the like called recycled plastics are mixed. If these specific gravities are recorded in advance, 0.91 to 0.97 for polyethylene, 0.90 to 0.91 for polypropylene, 1.05 for polystyrene, 1.34 for polyethylene terephthalate, and 1.16 for polyvinyl chloride. ~ 1.45. Since the specific gravity of polystyrene foam depends on the amount of bubbles contained, the specific gravity of polystyrene is shown here. These specific gravity values are based on “Introduction to Plastic Materials for Mold Engineers and Molding Engineers” (author: Kikuo Takano, published by Nikkan Kogyo Shimbun).
Of the above, recycled plastic P4 has polystyrene foam (polystyrene) as a main component, and recycled plastic P6 has polyethylene and polypropylene as main components.

  In the foreign matter removing process of step S1, foreign matter W1 such as metal, paper, and wood pieces mixed in the mixed waste plastic P1 is removed. Of these, the removal of metal is mainly performed using magnetism, and paper, wood pieces, large foamed polystyrene, etc. are removed manually. In some cases, mixed waste plastic P1 from which foreign matter W1 has already been removed is carried in.

  In the crushing process of step S2, the mixed waste plastic P1 after the removal of the foreign matter W1 in step S1 is crushed. Specifically, the crushed plastic P1 has a cubic shape with a side of about 2 cm.

In the floating sorting step in step S3, the mixed waste plastic P1 crushed in step S2 is put into a stirred water tank. Of the mixed waste plastic P1, the lightweight plastic P2 floats on the water surface. This lightweight plastic P2 is mainly foamed polystyrene, and also includes polyethylene, polypropylene and the like. In addition, the agitation water tank is provided with a screw capable of adjusting the agitation speed, and convection is generated in the water by the rotation of the screw. Therefore, the lightweight plastic P2 floats while being collected in the center of the convection.
On the other hand, the heavy object W2 settles on the bottom surface of the stirring water tank. The heavy object W2 includes metal and polyethylene terephthalate. These are then removed together.

  In the recovery step of step S4, the lightweight plastic P2 that has floated on the water surface is recovered. The collection is performed using a suction blower or the like. In the collected lightweight plastic P2, in addition to the foamed polystyrene alone, small pieces such as polyethylene and polypropylene, and other impurities may adhere to the foamed polystyrene.

  In the cleaning step of step S5, the collected lightweight plastic P2 is cleaned using water. Thereby, the above-mentioned deposits are separated from the expanded polystyrene. However, all deposits may remain attached without being separated, or the separated deposits may be reattached, and not all deposits are separated. .

  In the compression / dehydration process of step S6, the lightweight plastic P2 after washing is solid-liquid separated and compressed by a screw press dehydrator or the like. As a result, the lightweight plastic P2 is in a state where moisture remains in accordance with its moisture absorption capacity. At this time, when the compression is insufficient, excessive moisture remains, but when the compression is excessive, the crushing process in step S7 is not sufficiently crushed, so the compression is controlled so as to obtain an appropriate amount of moisture. .

  In the crushing step of step S7, the lightweight plastic P2 in which moisture remains is crushed by a blower blower or the like. In addition, it is necessary to disintegrate enough so that the selection precision of a polystyrene foam and other plastics may not fall in the wind power selection process of step S8.

In the wind power sorting process of step S8, the crushed lightweight plastic P2 is sorted into expanded polystyrene and other plastics.
First, a lightweight plastic P2 is put into a wind power sorter, and sorted using a difference in water absorption amount while being quantitatively supplied using a vibration feeder or the like. That is, there are cases where a heavy material (foamed polystyrene) with a large amount of moisture absorption and a light plastic P3 (main component polyethylene and other polypropylenes) with a small amount of water are contained. In this case, both the case of polyethylene alone and the case of containing polypropylene as a main component are collectively referred to as “polyethylene etc.”). In addition, the frequency of the vibration feeder should just be a grade in which the thrown-in plastic can advance ahead.
Moreover, it is made to advance ahead, and it blows from below by using a blower with respect to the crushed plastic. The frequency of the blower is preferably adjusted so that the weight ratio of the light object to the crushed plastic is about 3 to 10%. By using the fact that polyethylene or the like having a small water absorption amount by blowing is scattered further away, the selection between polystyrene foam and polyethylene or the like is performed. Thereafter, the polystyrene foam is sent to the drying process in step S9, and the plastic P3 such as polyethylene is sent to the recovery process in step S13.

  In the drying step of step S9, the selected foamed polystyrene is dried. Styrofoam is sent into a storage hopper and stirred with a screw while applying hot air inside. Note that the temperature of the warm air is desirably about 80 ° C. Here, if the drying is insufficient, volume reduction / granulation becomes difficult in the volume reduction / granulation step of Step S10, so care must be taken.

  In the volume reduction / granulation step of step S10, the expanded polystyrene is granulated after volume reduction. By the steps so far, the recycled plastic P4 of the polystyrene foam is recycled.

In the centrifugal separation process of step S11, the plastic P5 other than the light weight plastic P2 that has floated on the water surface and the heavy material W2 that has settled on the bottom surface of the stirring water tank in the floating selection process of step S3 is charged into the centrifuge. The plastic P5 includes polyvinyl chloride and the like in addition to the main components polyethylene and polypropylene.
By rotating at high speed in the centrifuge, polyvinyl chloride having a specific gravity of 1 or more is removed.

  In the drying step of step S12, the centrifuged plastic P5 is dried.

  In the recovery process of step S13, plastic P3 such as polyethylene and polypropylene selected in the wind power selection process of step S8 is mixed into the dried plastic P5 to form flakes / fluffs. That is, through the steps so far, all the polyethylene and polypropylene contained in the mixed waste plastic P1 are recovered.

  In the granulation process of step S14, the flake / fluff-like plastic is granulated into pellets. Thereby, the recycled plastic P6 of polyethylene and polypropylene is regenerated.

In the present embodiment configured as described above, the crushed mixed waste plastic P1 is put into the stirring water tank, so that all the styrofoam, polyethylene, and polypropylene that cannot be manually selected due to the small particle size are collected. be able to. Therefore, there is little quantitative loss at the beginning of the process. Further, in the collected lightweight plastic P2, small pieces such as polyethylene and polypropylene adhering to the polystyrene foam can be washed and separated. However, not all the deposits are separated, which causes a decrease in the purity of the recycled plastic P4. However, the deposits are removed from the expanded polystyrene by providing the compression process in step S6 or the wind sorting process in step S8. Separation with high accuracy is possible.
This compression dehydration process utilizes the property that the water absorption capacity of the crushed expanded polystyrene is higher than that of other plastics so that only the expanded polystyrene is selectively separated. At this time, compression is performed to obtain an appropriate amount of water. Here, the compression that provides an appropriate amount of water refers to compression in a range in which the degree of separation of foamed polystyrene and polyethylene does not decrease. This is because in the case of insufficient compression, moisture remains in the adhering portion of the expanded polystyrene and polyethylene, and in the case of excessive compression, the crushing is insufficient, and in any case, the degree of separation between expanded polystyrene and polyethylene decreases. This is because the purity of the recycled plastic P4 of polystyrene foam is lowered. Therefore, by controlling the compression so that the degree of separation does not decrease, it always contributes to the production of recycled plastic P4 of high-purity polystyrene foam.
And in a crushing process and a wind-power selection process, since a polystyrene foam, polyethylene, etc. are isolate | separated further more accurately, the quantity of the polyethylene etc. mixed in a polystyrene foam can be made very small. Therefore, the amount of non-recyclable plastic waste due to a decrease in purity is also small. Therefore, it is possible not only to recycle the high-purity polystyrene foam recycled plastic P4 but also to increase the amount of the recycled plastic P4.
In the wind sorting process, polyethylene and polypropylene are also separated, and in the collecting process in step S13, all polyethylene and polypropylene contained in the mixed waste plastic P1 are collected, so that the amount of plastic P6 recycled is improved. be able to. Moreover, since substances other than polyethylene and polypropylene are removed by the steps so far, the high-purity plastic P6 can be regenerated.
As described above, in the mixed waste plastic recycling method according to the present embodiment, attention is paid to the property of specific moisture absorption ability of the crushed foamed polystyrene, and the moisture content is maintained within a desired range by compression control. By doing so, it is possible to recycle recycled polystyrene foam having high purity and good regeneration efficiency. In addition, since a small amount of polyethylene attached to the crushed polystyrene can be collected without exception, two types of recycled plastics P4 and P6 with high purity and high recycling efficiency can be recycled at the same time, contributing to the reduction of waste. Can do.
Moreover, in any process, since general equipment such as a stirred water tank, a screw press dehydrator, and a blower blower is used, the equipment cost is not particularly burdened, and the existing processing facility is slightly affected. It can be introduced by simple modification.
Hereinafter, the mixed waste plastic recycling method according to the present embodiment will be described with reference to examples.

Next, a specific configuration of the embodiment will be described. Of course, the present invention is not limited by this illustration.
First, Table 1 shows the moisture content (%) for each type of plastic. When the dry weight of the plastic is a (g) and the weight including moisture is b (g), the moisture content c (%) is represented by (ba) / b × 100.

  As shown in Table 1, the moisture content c of the two types of polystyrene foams is sufficiently larger than that of polyethylene and polypropylene. Moreover, the higher the foaming ratio of the expanded polystyrene, the greater the water content c, but the difference is slight. Therefore, if this moisture content c is used as an index, styrene foam, polyethylene, and polypropylene can be separated with high accuracy.

  Next, the moisture content c (%) with respect to the back pressure p (MPa) and the purity d (%) of the polystyrene foam are shown. Here, the back pressure p is the pressure of the screw press dehydrator added to the plastic P2 in the compression dehydration process of step S6, and the purity d is a weight ratio, and the dry weight (g) of the polystyrene foam / recycled plastic. It is the dry weight (g) of P4.

  As shown in Table 2, when the back pressure p was 0.1 to 0.8 (MPa), high-purity polystyrene foam having a purity d of 90% or more was obtained. Of these, when the back pressure p was 0.3 to 0.6 (MPa), the most pure (95%) polystyrene foam was obtained. That is, if the moisture content c is 42 to 11 (%), the polystyrene foam can be made to have a high purity (90% or more), and in order to obtain the highest purity (95%), the moisture content c is set to 30 to 15 ( %) Is desirable.

Table 3 shows the contents and purity of recycled plastic P3 and recycled plastic P5 according to the present embodiment and conventional examples 1 to 3 as comparative examples. In this embodiment, the back pressure p is 0.5 (MPa), the moisture content c is 18 (%), and the drying temperature is 80 ° C.

As shown in Table 3, according to the present embodiment, it is possible to regenerate high-purity recycled plastics P4 and P6 with very few contaminants. In the purity d in the rightmost column of Table 3, “high” is 90% or more, “medium” is less than 90% and 80% or more, and “low” is a purity (weight) of less than 80%. Ratio).
On the other hand, in Conventional Example 1 (see FIG. 2), the polystyrene is mixed in the main component and the purity is low. In the conventional example 2 (see FIG. 3), the yield of the recycled plastic Y is high but the yield is low. Further, polyethylene or the like is mixed into the recycled plastic Z, and the purity remains low. In the conventional example 3 (see FIG. 4), the recycled plastic A is high in purity with few contaminants, but the recycled plastics B and C are not high in purity due to the contaminant.
That is, only this embodiment can make all recycled plastics high purity among this embodiment thru | or the prior art example 3. FIG. Therefore, according to the mixed waste plastic recycling method according to the present embodiment, it is possible to reduce the amount of the mixed waste plastic that is a raw material to be discarded. Accordingly, it is possible to increase the purity of the recycled plastics P4 and P6 and improve the quality at the same time, and improve the processing efficiency and increase the amount of each recycled.

  The method for recycling mixed waste plastic according to the present invention is not limited to that shown in this embodiment. For example, the moisture content c need not be fixed at 18 (%) as long as the purity d of the expanded polystyrene is 90 (%) or more.

The inventions described in claims 1 to 4 can be applied as a recycled processing method of recycled plastic of polystyrene and recycled plastic of polyethylene and polypropylene.

  P1: Mixed plastic waste P2: Lightweight plastic P3, P5: Plastic P4, P6: Recycled plastic W1: Foreign matter W2: Heavy

Claims (4)

In the recycling treatment method of mixed waste plastic containing polystyrene foam and other plastics,
Crushing step of crushing the mixed waste plastic;
The mixed waste plastics and crushing was put in a water tank, a compression dehydration step of compressing dehydrating the mixed waste plastic these were floating on the surface,
A crushing step of crushing the mixed waste plastics and compression dehydration,
Blown into the mixed plastic waste was disintegrated, and the the mixture waste plastics foam, and wind sorting step of sorting from the styrofoam and lightweight said other plastics, in,
A centrifugation step to remove the specific gravity of one or more polyvinyl chloride remaining the mixed plastic waste from the water tank after removing the mixed waste plastics was compressed dehydration by centrifugation,
A recovery step of mixing lightweight the other plastic than the Styrofoam that the mixing waste plastic centrifugation were screened in the wind sorting step,
A method for recycling mixed waste plastics, comprising: The compression dehydration step, compressed dehydrated process for regeneration of a mixed waste plastics according to claim 1, characterized in that the adjustable moisture content of the mixed waste plastic.   The method for reclaiming mixed waste plastic according to claim 2, wherein the moisture content is 10 to 45%. The method for reclaiming mixed waste plastic according to any one of claims 1 to 3, wherein the other plastic lighter than the expanded polystyrene is polyethylene or polypropylene.

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