JP2004209752A - Method for separating mixed waste plastics - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for separating mixed waste plastics capable of sharply lowering the chlorine content of a separated chlorine-free plastics. <P>SOLUTION: In the method for separating mixed waste plastics using a melt granulation device for softening/melting plastics by stirring friction heat to granulate the same, the waste plastics wherein at least two kinds of plastics containing a chlorine-containing plastic are mixed is charged in the melt granulation device to be set to a temperature melting the chlorine-free plastic among the mixed plastics to granulate the same but not melting the chlorine-containing plastic. After the mixed waste plastics is stirred under such a condition that the chlorine content of the granulated chlorine-free plastic becomes a predetermined value or less, a cooling fluid is introduced into the melt granulation device to cool the waste plastics. The mixed plastics discharged from the melt granulation device is separated into a granular plastic and a non-granular plastic. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００６６】
実施例１と比較例１の結果を比較してみると、実施例１で得られた粒状物の塩素含有率は比較例１の値に比べて格段と低い０．４％ｗｔになっており、例えば、高炉へ吹き込む場合の塩素含有率の許容値を下回っている。このことは、実施例１においては、回転方向の先端部が円弧状に形成された攪拌羽根を備えた溶融造粒装置が使用され、装入されたプラスチックの切断がごく僅かに抑えられたためであると考えられる。すなわち、上記塩素含有率の低下は、プラスチックの切断がごく僅かに抑えられ、粉状や細粒のＰＶＣの発生量が少なかったことにより、非塩素含有プラスチックの粒子に付着するＰＶＣが少量にとどまったことによる効果であると言うことができる。
【００６７】
又、粒状化の度合いをみると、実施例１の粒状物の回収率（粒状化率）が比較例１の結果よりも高く、例えば、高炉吹き込みの用途には好ましくない２ｍｍ未満の粒状物の割合は比較例１の結果よりも大幅に少なくなっており、本発明の方法が造粒効率（非塩素含有プラスチックの回収率）がよい方法であることを示している。そして、溶融造粒装置から排出される処理物には、細かな造粒物が少ないので、造粒物と非造粒物の分離が容易である。
【００６８】
良好な造粒効率は、装入されたプラスチックが攪拌羽根で切断されることによって発生する小片の量が少ないこと、及び造粒されたプラスチックの粒子が攪拌羽根によって破砕される現象が起こりにくいためであると考えられる。
【００６９】
上記の実施例１においては、１種類の非塩素含有プラスチック（ＰＥ）と１種類の塩素含有プラスチック（ＰＶＣ）の混合物から塩素含有プラスチックを分離する操作を行った場合について説明したが、前述のように、分離処理を行うプラスチックが多種類の混合物であっても、それぞれのプラスチックを分離することができる。混合されているプラスチック間の溶融点の差に基づて処理温度を設定し、溶融造粒処理を順次繰り返して行えば、混合廃プラスチック系廃棄物からＰＥ、ＰＳ、ＰＥ等の非塩素含有プラスチックの粒状物が分離して得られ、分離されたそれぞれの種類に適した用途に再利用することができる。
【００７０】
【発明の効果】
以上説明した本発明によれば、混合廃プラスチックから分離された非塩素含有プラスチックの塩素含有率を大幅に低下させることができる。このため、廃プラスチックを多方面の用途に供することができる。
【００７１】
又、多種類の混合廃プラスチックから種類別にプラスチックを分離することができ、それぞれの種類のプラスチックに適した用途に再利用することができる。
【図面の簡単な説明】
【図１】本発明の方法を実施するための溶融造粒装置に係る構成の一例を示す斜視図である。
【図２】攪拌機の攪拌羽根の構造を示す図である。
【図３】図２ （ｂ）におけるＡ−Ａ部の断面を示す図である。
【図４】他の形状の攪拌羽根における主羽根の端部の断面を示す図である。
【図５】エアテーブル型乾式比重形状分離装置を示す斜視図である。
【図６】塩素含有プラスチックの分離が不十分になる状態の説明図である。
【図７】比較例の試験に用いた攪拌羽根の端部の構造を示す図である。
【符号の説明】
１０ 溶融造粒槽
１１ 攪拌機
１２ 攪拌機の攪拌羽根
１３ 攪拌羽根を駆動するモータ
１４ 装入口
１５ 排出口
１６ 排出ゲート
２２ 主羽根
２３ 縦羽根
２４ 主羽根の端部
３０ 振動篩
３１ 邪魔板
４０ 振動方向
４１ 上昇空気流
５０ プラスチック片
５１ 非塩素含有プラスチックの粒子
５２ 粉状や細粒の塩素含有プラスチック
５３ 粒状物と非粒状物の混合物
５４ 粒状物
５５ 非粒状物[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to chlorine-containing plastics (PVC (polyvinyl chloride) and PVDC (polyvinylidene chloride)) (hereinafter referred to as PVC and / or PVDC) from plastic waste in general and industrial wastes. relates to a method of separating a) that contain plastic ".
[0002]
[Prior art]
Plastic waste generally referred to as waste plastic includes a plurality of types of plastics, and includes polystyrene (PS), polyethylene (PE), polypropylene (PP), etc., as well as PVC (polyvinyl chloride) and PVDC (polyethylene). also it includes chlorine-containing plastics vinylidene chloride) and the like. In the treatment of waste plastics containing such chlorine-containing plastics, the following problems arise.
(1) When heat treatment such as incineration is performed, chlorine-containing plastics are thermally decomposed to emit toxic hydrogen chloride gas.
One method to effectively use the (2) waste plastics, steel mills, there is a blown method blast furnace as iron source reducing agent, hydrogen chloride gas is generated by thermal decomposition of chlorine-containing plastics, equipment there is a problem that is corrosion. For this reason, in order to effectively use the waste plastic, it is necessary to perform a pretreatment for removing the chlorine-containing plastic in advance, so that the content rate becomes equal to or less than an allowable value.
[0003]
Meanwhile, as a technique for separating the mixed plastic waste by type, stirring the waste plastics containing a plurality of kinds of plastics by generating frictional heat generated by the collision of the plastic pieces to each other, the temperature to a temperature at which the plastic of interest is melted with stirring There is a method in which the plastic is granulated by heating, and the granulated plastic is separated from the non-granular plastic (for example, Patent Document 1).
[0004]
In Patent Literature 1, waste plastic containing a plurality of types of plastics is crushed by a fixed blade body and a rotary blade body, and the crushed product is agitated and heated to be granulated, and the granulated material and crushed pieces are separated. Accordingly, a method for separating a plurality of types of plastics is described. According to this method, the chlorine-containing plastic can be separated from the mixed waste plastic.
[0005]
Since the apparatus used in the method described in Patent Document 1 includes a fixed blade and a rotary blade, a function of crushing the mixed waste plastic into small pieces and a function of increasing the temperature of the crushed small pieces are provided. , and a function of granulating the small piece was raised. For this reason, in the method of Patent Literature 1, a series of processing including crushing, heating, and granulation is performed by performing only one operation of charging the mixed waste plastic into the apparatus and stirring.
[0006]
[Patent Document 1]
Japanese Patent Publication No. 54-31022
[0007]
[Problems to be solved by the invention]
However, according to the research results of the present inventors, when the above-described conventional method is applied to a process of separating and removing chlorine-containing plastic from a mixed plastic, the chlorine content of the obtained granular material of non-chlorine-containing plastic is determined. And the granular material was not able to be used effectively.
[0008]
The present invention has been made to solve the above problems, aims to provide an isolated can significantly reduce the chlorine content of the chlorine-containing plastics, the method of separating mixed waste plastics And
[0009]
[Means for Solving the Problems]
The present inventors have conducted a study of the separation process of the plastic mixture in the prior art, a major cause for the chlorine content of the particulate material of non-chlorine-containing plastics obtained becomes high, during the granulation process It was concluded that chlorine-containing plastic adhered to non-chlorine-containing plastic that was melted and granulated. The conclusion to reach results of the study are as referred to below.
[0010]
As described above, in the apparatus used in the prior art described above, the processing tank fixed cutter blade is provided, since the rotary blade body is provided with a stirrer disposed in the processing tank, charged After the mixed waste plastic is cut into small pieces, the small pieces are melted and granulated. At this time, the waste plastic charged into the device is cut as a whole without distinction in its type, and then the non-chlorine-containing plastic of the cut mixed plastic is granulated to become granules. And non-granulated plastic containing chlorine.
[0011]
However, although non-chlorine-containing plastics is cut to a size for the granules of the planned size, also performed at the same time cutting the chlorine-containing plastics, in this case, plastic powder or granules is produced. Then, as shown in FIG. 6, the molten granulated or deposited chlorine-containing plastic 52 powdery or granule has a particle 51 of the non-chlorine-containing plastics, or particles 51 to each other adhesion of chlorine-containing plastic and when it becomes a single particle, the phenomenon occurs to or chlorine-containing plastic 52 powdery or fine is confined therein, the separation of the chlorine-containing plastics and chlorine-containing plastics is insufficient.
[0012]
The present invention has been made based on the above-described study results, and has the following features.
[0013]
The method of separating mixed waste plastics according to the invention of claim 1 is a method of separating mixed waste plastics using a melt granulation device for granulating softened and melted plastic by agitation of frictional heat, the chlorine-containing plastic The waste plastic mixed with two or more kinds of plastics including is mixed into a melt granulation apparatus, and the mixed plastic is brought to a temperature at which non-chlorine-containing plastic is melted and granulated and chlorine-containing plastic is not melted. After stirring under the condition that the chlorine content in the granulated non-chlorine-containing plastic is equal to or lower than a predetermined value, a cooling fluid is introduced into the melt granulator, cooled, and the mixture discharged from the melt granulator is mixed. It is characterized by separating plastic into granular and non-granular materials.
[0014]
The method of separating mixed waste plastics according to the invention of claim 2 is a method of separating mixed waste plastics using a melt granulation device for granulating softened and melted plastic by agitation of frictional heat, the chlorine-containing plastic two or more waste plastics plastic is mixed to the size of the granules having a predetermined particle size range, charging the waste plastics into the melt granulation apparatus having a stirrer having substantially no cutting function comprising After mixing, the non-chlorine-containing plastic of the mixed plastic is melted and granulated, and the temperature is adjusted so that the chlorine-containing plastic is not melted. It is characterized in that the mixed plastic discharged from the granulator is separated into granular and non-granular materials.
[0015]
According to a third aspect of the present invention, there is provided a method of separating mixed waste plastic according to the first or second aspect, wherein the chlorine-containing plastic is polyvinyl chloride and / or polyvinylidene chloride. .
[0016]
As described above, the reason why the separation of the non-chlorine-containing plastic and the chlorine-containing plastic is not sufficiently performed is mainly that the chlorine-containing plastic adheres to the melted and granulated non-chlorine-containing plastic, the cause is cleaved chlorine-containing plastics that have been charged, plastic powder or granules are produced, because the chlorine-containing plastics powdery or granule has adhered to the non-chlorine-containing plastic particles.
[0017]
Therefore, in the method of the present invention, the stirring is performed under the condition that the chlorine content in the non-chlorine-containing plastic granulated and separated is equal to or less than a predetermined value. The stirring under the condition that the chlorine content is equal to or less than a predetermined value means that: (1) heat is generated by generating frictional heat and granulated molten plastic so that cutting of the plastic is minimized. it refers to the stirring state of interest only. In order to perform such stirring, operating conditions such as the structure of the stirrer and the rotational speed of the stirrer (peripheral speed of the blade) are appropriately set.
[0018]
Further, the waste plastic is charged into a melt granulation apparatus provided with a stirrer having substantially no cutting function and stirred.
[0019]
Therefore, according to the method of the present invention, since the generation of powdery or fine plastic is minimized, even powdery or fine chlorine-containing plastic is attached to the non-chlorine-containing plastic particles, the amount is just Can be limited to a certain amount. For this reason, plastic granules having a low chlorine content can be obtained.
[0020]
Note that the above-mentioned substantially no stirrer cutting function, not intended to impart a function of cutting the charge, means a structure having a normal function of agitating the charge ing. For this reason, it does not mean that there is no generation of slight powder or fine particles caused by grinding or the like. As the stirrer, for example, a stirrer having no portion having an acute angle such as a blade in the rotation direction of the blade can be used.
[0021]
Thus, in the present invention, since the cutting of the plastic in the melt granulation is minimized, the mixed waste plastics, crushed to a size of the granules having a predetermined particle size range, the melt granulation device Charge. The reason is as follows.
[0022]
In melt granulation apparatus used in the present invention, since the cutting of the plastic is suppressed, plastic particles generated charged by individual plastic pieces is softened and melted, in which the plastic pieces with rounded . For this reason, the particle size of the generated plastic particles is not clear because it has an effect due to shrinkage or adhesive bonding, but is generally determined by the size (volume) of the inserted plastic piece.
[0023]
Thus, in the present invention, the waste plastics are charged into the melt granulation apparatus, in advance, so keep the size of granules of a predetermined grain size is obtained, to easily obtain granules of the desired particle size In addition, a granular material having a uniform particle size can be obtained.
[0024]
Then, in the method of the present invention using the melt granulation device, the heating of the plastic is carried out by frictional heat generated by with the rotation of the agitator, unlike the case where the external heating by a heater, the entire tank plastic is uniformly heated without temperature variations. Therefore, the temperature of the plastic during processing is accurately managed.
[0025]
Further, the stirring promotes the granulation due to the physical collision effect of the stirring. In addition, when plastic is heated, adhesion bonding occurs due to surface adhesion generated with the temperature rise, and the generated granular material grows in a large diameter and grows like a snowball, but in the present invention, frictional heat of stirring causes since heating the plastic, adhesion coalescence of the particles is suppressed.
[0026]
In the above description, the temperature of the plastic is raised only by the frictional heat generated by the stirring, but other heating means such as a heater may be used in combination.
[0027]
Waste plastics was heated by agitation of frictional heat by the stirring means, and granulated by forced cooling, and, for other plastics in waste plastic from being granulation, require precise temperature control is there. In particular, cooling control is important to keep non-granulated plastics that are not desired to be granulated. That is, temperature control of waste plastic during stirring is an important point in selecting and granulating waste plastic by type (by material).
[0028]
As a temperature measuring means for controlling the temperature of the waste plastic, it is preferable to use a non-contact radiation thermometer or the like which can accurately measure without a time delay. Then, at the stage where the waste plastics in the agitation has reached a predetermined temperature that is granulated, on the basis of the output from the temperature measuring means, it is introduced to the cooling fluid by operating the cooling means, attached between the particles large The granulation process can be ended in an appropriate state without causing the problem.
[0029]
The timing for cooling the warmed waste plastics, when the surface of the heated to the stirring of agitation state and the molten plastic and non-melt plastic mixed became granular reaches a predetermined temperature by stirring the frictional heat It is. By cooling at this timing, the granulated particles are solidified, and a granular material having a uniform particle size within a certain size range can be obtained.
[0030]
For example, when the cooling temperature is set to a predetermined temperature at which PP can be melt-granulated, PVC and PVDC having a melting point higher than that are not melted, the shape is not changed, and the lump or fragment remains as it is. is there. In this way, the charged mixed plastic is formed into a mixture of a solidified PE, PS, or PP-based plastic (non-chlorine-containing plastic), a non-granular material including PVC and PVDC, and paper. Can be.
[0031]
As a method of cooling the waste plastic heated by stirring, it is preferable to perform forced cooling in which the cooling time is forcibly advanced within a certain time to cool the waste plastic. Adhesive force is generated on the surface of the waste plastic as the temperature rises. However, due to the above-mentioned stirring effect, the adhesion bonding is prevented during the stirring. However, when the material is removed from the stirring state (when the stirring is completed), a phenomenon occurs in which the particulate matter adheres to each other and forms a mass. At this time, this can be prevented by performing forced cooling and cooling in a short time. As one of the forced cooling means, there is a method of spraying a cooling fluid such as water or liquid nitrogen. If the forced cooling is performed with liquid nitrogen, the cooling time of the waste plastic can be shortened and the processing efficiency can be improved.
[0032]
The mixture of the PE, PS, PP-based plastic (non-chlorine-containing plastic), the non-granular material including PVC and PVDC, and the paper, which has been subjected to the cooling treatment as described above, is subjected to dry specific gravity shape separation. It is introduced into a dry separation means such as a device or a wind separation device, and is separated into granular materials and non-granular materials and papers.
[0033]
At this time, even when a wet plastic is charged into the melt granulation apparatus, the plastic is dried by raising the temperature due to frictional heat of stirring, and even if forced cooling for spraying a cooling fluid is performed, Since the cooling fluid is vaporized by the heat retained by the plastic itself, a step of drying the separated plastic is not required.
[0034]
The PE, PS, PP-based plastic (non-chlorine-containing plastic) granules thus separated are used as a reducing agent of an iron source to be blown into a blast furnace of an ironworks, or as a raw fuel to be injected into a cement kiln or the like. It can be used as fuel or the like.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an example of a configuration relating to a melt granulation apparatus for carrying out the method of the present invention. Melt granulation apparatus shown in Figure 1 to generate frictional heat by the rotation of the stirrer, a melt granulation device for granulating molten plastic, 10 and granulated was charged with mixed waste plastic melt granulation A granulating tank, 11 is a stirrer for stirring the mixed waste plastic charged in the molten granulating tank, 12 is a stirring blade of the stirrer, 13 is a motor for driving the stirring blade, 14 is a charging port, and 15 is a discharge port. 50 indicates a plastic piece.
[0036]
The stirrer 11 is disposed below the melt-granulation tank 10, and the stirrer 12 that rotates in the circumferential direction of the melt-granulation tank 10 is arranged in the stirrer 11 substantially in parallel with the bottom surface of the melt-granulation tank 10. The stirring blade 12 of the stirrer has the structure shown in FIGS. 2 (a), (b) and FIG. 2A is a front view, FIG. 2B is a plan view, and FIG. 3 is a view showing a cross section taken along the line AA in FIG. 2B. The stirrer has a structure in which a plurality of stirring blades 12 are attached to a rotating plate 21 which is provided on the bottom of the melt granulation tank 10 and is mounted on a rotating shaft 20. The mixed waste plastic charged therein is agitated.
[0037]
Stirring blade 12 is made of vertical vanes 23 provided upright to the main blade 22 formed parallel to the bottom surface thereon, and is a structure having no substantial cut function. That is, the main blade 22 has a shape obtained by cutting a flat plate as it is, and there is no sharp-angled portion such as a blade at the end in the rotation direction of the stirring blade 12 (end 24 of the main blade). Therefore, the stirring blade 12 is cut function is not added.
[0038]
In the present invention, the stirring blade not provided with the cutting function includes one having an end in the rotation direction having the shape shown in FIG. FIG. 4 is a diagram showing a cross section of an end portion 24 (an end portion in the rotation direction of the stirring blade) of the main blade in another shape of the stirring blade. None of the main blades shown in FIG. 4 has an acute cross-sectional shape at the end. (A) The main blade shown in FIG. The main blade has an obtuse angled mountain shape at the end in the rotation direction.
[0039]
Incidentally, the melt granulation apparatus of Figure 1, but agitator 1 groups are provided, the number of agitator is not intended to be limited to one group, or two groups of agitator may be provided.
[0040]
Further, melt granulation apparatus of Figure 1 is means for raising the temperature of the mixed waste plastic is only stirrer, a formed heating means such as a heater for supplying heat from the outside, may be used together.
[0041]
Although the main blade 22 of the stirring blade shown in FIG. 2 is a flat plate formed parallel to the bottom surface, the stirring blade used in the present invention is provided only for stirring, so The shape is not limited as long as the portion is not formed in an acute shape. For example, the main blade 22 may have a shape inclined with respect to the bottom surface.
[0042]
The separation processing of the mixed waste plastic using the melt granulation apparatus having the above configuration is performed as follows. In the description of the separation method, a method of separating a waste plastic to be processed from a film or a thin plate used for a container or a packaging will be described.
[0043]
As mentioned above, plastic particles formed in the melt-granulation device is individual plastic pieces is softened and melted charged, since those wherein the individual plastic pieces with rounded, in the present invention, The mixed waste plastic is sized to obtain a desired particle size, and then charged into a melt granulation apparatus.
[0044]
For this reason, the mixed waste plastic is crushed in advance, or crushed and then sieved to a predetermined size. Or, performing the crushing by the sieve with the crusher. For example, it keeps from the 0.05mm about waste plastic thickness if the range of the particle size to be obtained granules of about 3.0 to 5.0 mm, the waste plastics to a size of about 15~50mm angle . However, if the size of the plastic is uniform, the temperature for melting and granulating becomes more stable, so that it is preferable that the size is approximately 30 mm square.
[0045]
The size of the mixed waste plastic to be charged into the melt granulator is about 15 to 50 mm square. If the plastic piece is smaller than 15 mm square, the chlorine-containing plastic easily adheres to the granular material of the non-chlorine-containing plastic. Become.
If the size exceeds 50 mm square, the plastic in a state where only the ends are melted remains and becomes mixed with the granular material.
[0046]
The mixed waste plastic prepared as described above is charged into a melt granulation apparatus. The charged plastic 50 is stirred by the stirring blades 12 to generate frictional heat, and the temperature of the plastic 50 rises. When the surface temperature of the material to be stirred (waste plastic 50) reaches a predetermined temperature at which the plastic to be granulated is melted, the plastic to be granulated is granulated.
[0047]
Well stirrable by melt granulation vessel, in order to obtain a uniform temperature distribution, agitator rotational speed peripheral speed of the stirring blade 12 is better to so that the 35m / sec~85m / sec.
[0048]
The surface temperature of the object to be stirred is measured by a radiation thermometer (not shown) provided in the melt granulation apparatus. Then, when the measured value of the radiation thermometer reaches a predetermined temperature at which the plastic to be granulated is melted, cooling water is sprayed onto the object to be stirred to be forcibly cooled. By this water injection, the plastic that has been melted and granulated solidifies in a granular state, and the plastic granules, non-granules, and other papers are mixed in the melt granulation device with almost no bonding. It becomes.
[0049]
The amount of cooling water, a waste plastic 1kgf per 0.05～0.2L. Forced cooling methods are not limited to water injection. For example, conceivable means, such as addition of liquid nitrogen. By performing the forced cooling with liquid nitrogen, the cooling time of the waste plastic heated by the frictional heat of stirring can be shortened, and the processing efficiency can be improved.
[0050]
The timing of forced cooling when the granulation target plastic is obtained by the melt granulator is as follows. That, ▲ 1 ▼ If granulation target plastics PE, the PS, when the temperature of the stirred material (waste plastic) is increased to 100~150 ℃, ▲ 2 ▼ If granulation target plastic is PP, 130 It rose to 170 ° C., respectively to initiate cooling. Thus, by granulation and melting point of the target plastics timing of the forced cooling is set slightly different predetermined temperature, by selecting the granulation target plastics can be granulated has been confirmed by the inventors.
[0051]
The mixed waste plastic 50 introduced into the melt granulation apparatus is agitated in a dry manner by the stirring blades 11, 11, and the temperature rises due to frictional heat. Cooling water at the temperature of the plastic 50 has reached a predetermined temperature below the melting temperature of the PVC and PVDC (not shown) is injected, molten plastic solidifies while the granular state. By setting the cooling water injection temperature to a predetermined temperature lower than the melting temperature of PVC and PVDC, in this embodiment, 150 to 190 ° C., plastic (plastic containing non-chlorine) having a lower melting temperature than PVC and PVDC Is melt-granulated.
[0052]
The mixture of the granulated granulated plastic (non-chlorine-containing plastic), non-granulated plastic (including PVC and PVDC) and papers is discharged by opening a gate 16 provided at a discharge port 15. , To the next separation step. At this time, the mixture can be discharged in a dry state by controlling the temperature of the mixture immediately after being discharged from the melt granulation apparatus to 100 to 115 ° C.
[0053]
The mixture of the cooled granules of plastics (non-chlorine-containing plastics) such as PE, PS, PP, etc., the non-granules including PVC and PVDC, and papers is used as a dry specific gravity shape separation device or a wind separation device. Etc., and is separated into granular materials and non-granular materials and papers.
[0054]
For example, the separation of granular material and non-granular material by an air table type dry specific gravity shape separation device shown in FIG. 5 is performed as follows. This specific gravity shape separation device includes a vibrating sieve 30 that can vibrate substantially horizontally in a vibrating direction 40 and a plurality of baffle plates (ruffles) 31 arranged on the vibrating sieve 30 in a direction substantially the same as the vibration direction. The vibrating sieve 30 is inclined (end slope) toward the vibration direction 40 and inclined (side slope) even in the horizontal direction orthogonal to the vibration direction 40. Then, the mixture 53 on the vibrating sieve 30 is separated into a granular material 54 and a non-granular material 55 due to a specific gravity difference and a shape difference by injecting the rising air flow 41 while vibrating the vibrating sieve 30 in the vibration direction 40. It is supposed to be.
[0055]
Thus, the mixture 53 of the granular material and the non-granular material discharged from the melt granulation device and introduced into the specific gravity shape separation device is a granular material 54 that is a non-chlorine-containing plastic and a chlorine-containing plastic including PVC and PVDC. It is separated into a non-particulate matter 55 and paper.
[0056]
The separated granulate contains no PVC and PVDC, can be reused as iron sources reducing agent feed applications, such as blast furnace blow Miya cement kiln. Here, when plastic granules (non-chlorine-containing plastics) are used as a raw material for blowing into a blast furnace, the particle size may be set to 2 to 20 mm in consideration of the cross-sectional area of the blowing port at the time of blowing the blast furnace. preferable.
[0057]
Next, examples of the present invention will be described.
(Example 1)
Using a melt granulation apparatus having the same configuration as that of FIG. 1, a process of separating chlorine-containing plastic from mixed waste plastic was performed. Processing conditions were as follows.
[0058]
Melt granulation equipment
Volume of melt granulation tank: 800 l
Stirring blade diameter: 800mm
The shape of the stirring blade: the shape shown in FIG. 4 (a), and the tip of the main blade is an arc
Main blade thickness: 25mm
Peripheral speed of the stirring blade: 40 m / sec
Treated mixed waste plastic sample
A mixture of waste plastics of PE and PVC was treated.
[0059]
PE: (film form, thickness about 0.06mm)
PVC: (film form, thickness about 0.05mm)
Before mixing, each waste plastic was crushed and then sieved to a size of 20 mm to 40 mm.
[0060]
The mixed waste plastic sample was charged into a melt granulation apparatus, and the temperature of the mixed waste plastic was increased by rotating a stirrer. When the temperature of the mixed waste plastic during stirring reached 160 ° C., the mixture was sprayed and cooled, and the temperature of the mixed waste plastic lowered to about 110 ° C. was discharged from the melt granulation apparatus. The discharged granulated product was mainly a mixture of PE in the form of granules of 4 mm to 8 mm and PVC which was not granulated in its original form.
[0061]
The granulated product was separated into granular PE and non-granular (chlorine-containing plastic) by a specific gravity shape separation device. Then, the particulate matter was analyzed for chlorine content. The particle size distribution of the particulate matter was examined. Table 1 shows the results of the above measurements.
(Comparative Example 1)
Using a melt-granulation apparatus provided with a stirrer in which the tip of the main blade of the stirrer was formed at an acute angle, a treatment for separating chlorine-containing plastic from mixed waste plastic was performed. The processing conditions were different from those of Example 1 in the following two conditions.
[0062]
{Circle around (1)} The stirring blade of the melt granulation apparatus had the shape shown in FIG. 7, and the tip of the main blade was formed at an acute angle and was in the shape of a blade.
[0063]
(2) The mixed waste plastic is charged in a size of 20 mm to 40 mm.
Granules (non-chlorine-containing plastics) melt-granulated under the above conditions mainly had a particle size of 2 mm to 7 mm.
[0064]
The same measurement as in Example 1 was performed for the melt-granulated discharge. The results are shown in Table 1 together with the results of Example 1.
[0065]
[Table 1]

[0066]
Comparing the results of Example 1 and Comparative Example 1, the chlorine content of the granular material obtained in Example 1 is 0.4% wt, which is much lower than the value of Comparative Example 1. For example, it is below the allowable value of the chlorine content when blowing into a blast furnace. This is because in the first embodiment, a melt granulation apparatus having a stirring blade having a circular arc-shaped tip in the rotation direction was used, and the cutting of the charged plastic was very slightly suppressed. It is believed that there is. That is, the decrease in the chlorine content is very small because the cutting of the plastic is suppressed very little, and the amount of the powdery or fine-grained PVC generated is small, so that a small amount of the PVC adheres to the particles of the non-chlorine-containing plastic. It can be said that this is the effect of the fact.
[0067]
As for the degree of granulation, the recovery rate (granulation rate) of the granular material of Example 1 is higher than the result of Comparative Example 1. For example, the granular material having a particle size of less than 2 mm, which is not preferable for blast furnace blowing, is used. The ratio is much lower than the result of Comparative Example 1, which indicates that the method of the present invention is a method having good granulation efficiency (recovery rate of non-chlorine-containing plastic). And since there are few fine granules in the processed material discharged from the melting granulator, it is easy to separate the granules from the non-granules.
[0068]
Good granulation efficiency is due to the small amount of small pieces generated by cutting the charged plastic with the stirring blade and the phenomenon that the granulated plastic particles are hardly crushed by the stirring blade. It is considered to be.
[0069]
In Example 1 described above, the case where the operation of separating the chlorine-containing plastic from the mixture of one type of non-chlorine-containing plastic (PE) and one type of chlorine-containing plastic (PVC) was described. In addition, even if the plastics to be separated are a mixture of various kinds, each plastic can be separated. If the processing temperature is set based on the difference in the melting point between the mixed plastics and the melt granulation process is repeated sequentially, non-chlorine-containing plastics such as PE, PS, and PE can be obtained from the mixed waste plastic waste. Can be obtained by separation, and can be reused for applications suitable for each type of separation.
[0070]
【The invention's effect】
According to the present invention described above, the chlorine content of the non-chlorine-containing plastic separated from the mixed waste plastic can be significantly reduced. For this reason, the waste plastic can be used for various purposes.
[0071]
Further, plastics can be separated from various types of mixed waste plastics by type, and can be reused for applications suitable for each type of plastic.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a configuration relating to a melt granulation apparatus for carrying out a method of the present invention.
FIG. 2 is a view showing a structure of a stirring blade of a stirrer.
FIG. 3 is a diagram showing a cross section taken along the line AA in FIG. 2 (b).
FIG. 4 is a diagram showing a cross section of an end portion of a main blade in a stirring blade having another shape.
FIG. 5 is a perspective view showing an air table type dry specific gravity shape separation device.
FIG. 6 is an explanatory view of a state where separation of a chlorine-containing plastic becomes insufficient.
FIG. 7 is a diagram showing a structure of an end portion of a stirring blade used in a test of a comparative example.
[Explanation of symbols]
10 Melt granulation tank
11 Stirrer
12 Stirrer stirring blade
13 Motor for driving stirring blades
14 Entrance
15 outlet
16 discharge gate
22 Main wing
23 vertical feather
24 End of main wing
30 vibrating sieve
31 Baffle
40 Vibration direction
41 Ascending air flow
50 plastic pieces
51 Particles of chlorine-free plastic
52 Powdery or fine-grained chlorine-containing plastics
53 Mixture of granular and non-granular materials
54 granules
55 non-granular materials

Claims (3)

In a method for separating a mixed waste plastic using a melting and granulating apparatus that softens and melts and granulates the plastic by frictional heat of stirring, the waste plastic mixed with two or more types of plastics including chlorine-containing plastic is melt-formed. The non-chlorine-containing plastic is charged into a granulating apparatus, and the non-chlorine-containing plastic is melted and granulated to a temperature at which the chlorine-containing plastic is not melted. After stirring under the condition that the value is equal to or less than the value, a cooling fluid is introduced into the melt granulation apparatus and cooled, and the mixed plastic discharged from the melt granulation apparatus is separated into a granular material and a non-granular material. Characterized method of separating mixed waste plastic. In a separation method of a mixed waste plastic using a melting and granulating apparatus that softens and melts and granulates the plastic by frictional heat of agitation, a waste plastic in which two or more types of plastics including chlorine-containing plastics are mixed has a predetermined particle size. The waste plastic is charged into a melt granulation apparatus equipped with a stirrer having substantially no cutting function and stirred, and the non-chlorine-containing plastic among the mixed plastics is melted. After the temperature is reduced to a temperature at which the chlorine-containing plastic is not melted and granulated and the chlorine-containing plastic is not melted, a cooling fluid is introduced into the melt granulator to cool the mixed plastic, and the mixed plastic discharged from the melt granulator is granulated and non-granulated. A method for separating mixed waste plastics, comprising separating the mixed waste plastics. 3. The method for separating mixed waste plastic according to claim 1, wherein the chlorine-containing plastic is polyvinyl chloride and / or polyvinylidene chloride.

Images