JPH1045941A - Method and apparatus for separating plastic waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for separating a plastic waste into a plastic component soluble in a separation solvent and a plastic component not soluble in the separation solvent by using a separation solvent. SOLUTION: In the method for separating plastic waste, (i) supplying the waste to a lower part of a solid-liquid contact zone composed of a screw conveyor having screw blades formed in a mesh structure, and moving the waste upward. ii) supplying a fractionating solvent from above or above the solid-liquid contact zone, contacting the waste and dissolving a part of the plastic in the waste, (iii) not dissolving in the fractionating solvent Recovering the plastic from the upper part of the solid-liquid contacting zone, (i.
v) A method for separating plastic waste, comprising recovering plastic dissolved in the separation solvent from a lower part of the solid-liquid contact zone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method and an apparatus for separating plastic waste.

[0002]

2. Description of the Related Art PE (polyethylene), PP (polypropylene), PS (polystyrene), PVC (polyvinyl chloride), PET (polyethylene terephthalate) and A
BS resin (acrylonitrile / butadiene / styrene copolymer) is widely used as a general-purpose plastic. Therefore, the majority of plastic waste consists of these plastics. At present, most of plastic waste is incinerated or landfilled without being reused, but such treatment is not desirable in terms of resource saving. Until now, various methods have been proposed for reusing plastic waste. One of the typical methods is a method of thermally decomposing oil into oil (pyrolysis oiling method). ing. In this method, a plastic waste is heated to a high temperature of about 450 ° C. to generate a cracked oil. In the thermal cracking and oiling method, when the plastic waste as the raw material to be treated is composed only of hydrocarbon-based plastics such as PE, PP, and PS, problems such as blockage troubles and corrosion of plants and pipes occur. And can be easily implemented. However, the raw materials to be processed are PE, P
Hydrocarbon plastics such as P and PS, and PVC and PE
When it is made of a mixture with a different hydrocarbon-based plastic such as T or ABS resin, various problems occur, and it is difficult to safely and stably perform the operation. For example, PVC
When mixed with hydrogen chloride, highly corrosive hydrogen chloride is generated, causing corrosion of equipment and piping. When PET is mixed, phthalic acids are generated by its thermal decomposition, and this causes a piping blockage trouble. When ABS resin is mixed, toxic hydrogen cyanide is generated by its thermal decomposition. As described above, when plastic waste is converted to pyrolysis oil, it is desirable to remove the different hydrocarbon-based plastics from the waste in advance. There is no known industrially advantageous method for separating hydrogen-based plastics from plastics, and there are many practical applications of methods for thermally decomposing plastic waste containing hydrocarbon-based plastics and different hydrocarbon-based plastics into oil. Difficulties have arisen.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for separating a plastic waste into a plastic component soluble in a separating solvent and a plastic component not soluble in the separating solvent by using a separating solvent. .

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, in the method for separating plastic waste, (i) the waste is supplied to a lower portion of a solid-liquid contact zone composed of a screw conveyor having screw blades formed in a mesh structure and moved upward. To make
(Ii) supplying a fractionating solvent from above or above the solid-liquid contact zone, contacting with the waste, and dissolving a part of the plastic in the waste; (iii) dissolving in the fractionating solvent Recovering from the upper part of the solid-liquid contact zone the plastic that has not been collected, and (iv) recovering the plastic dissolved in the separation solvent from the lower part of the solid-liquid contact zone. Provided. Also,
According to the present invention, in an apparatus for separating plastic waste using a separation solvent, (i) the entirety is formed in a cylindrical closed container, and (ii) the waste is placed inside the container from below. (Iii) a supply mechanism for supplying the waste to the lower part of the solid-liquid contact zone at the lower part of the container, wherein the screw vanes to be moved to have a solid-liquid contact zone composed of a screw conveyor formed in a mesh structure. Having
(Iv) having a discharge mechanism at the top of the container for discharging plastic not dissolved in the separation solvent, (v)
An apparatus for separating plastic waste is provided, which has a supply pipe at the top or top of the vessel for supplying a separation solvent above or above the solid-liquid contact zone.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Plastic waste used as a raw material to be treated in the present invention is composed of a plastic component soluble in a separation solvent and a plastic component insoluble in the separation solvent. Representative examples of such plastic wastes include those composed of hydrocarbon-based plastics and different hydrocarbon-based plastics. Hydrocarbon plastics include polyolefin plastics such as PE and PP and aromatic plastics such as PS,
The different hydrocarbon plastics include PVC, PET and A
BS resin and the like are included. All of these plastics are general-purpose plastics that are produced in large quantities, and the bulk of plastic waste consists of these plastics. Of course, the plastic waste in this case can contain a hydrocarbon-based plastic and a different hydrocarbon-based plastic other than the above-mentioned plastics, but the ratio is usually 30% by weight or less. In general plastic waste, the proportion of hydrocarbon plastic is usually 50% by weight or more, and sometimes 75% by weight.
% By weight or more.

[0006] The fractionating solvent used in the present invention has a dissolving property that dissolves some plastics in plastic waste and does not dissolve other plastics. For example, for a plastic waste consisting of the hydrocarbon-based plastic and the different hydrocarbon-based plastic, one that selectively dissolves only the hydrocarbon-based plastic and does not substantially dissolve the different hydrocarbon-based plastic is selected. As such a fractionating solvent, a liquid hydrocarbon mixture containing an aromatic hydrocarbon and a paraffinic hydrocarbon can be used. Such a mixed solvent has the advantage of being inexpensive because it can be easily prepared using a product oil obtained by pyrolyzing a hydrocarbon-based plastic contained in plastic waste.

As the separation solvent used in the present invention, an appropriate solvent is selected and used according to the plastic component to be separated. The separation solvent comprises a hydrocarbon plastic and a different hydrocarbon plastic which are general plastic waste. As the separation solvent for separating the plastic waste into the two components, a liquid hydrocarbon mixture containing an aromatic hydrocarbon and a paraffinic hydrocarbon can be preferably used as described above. Hereinafter, the fractionation solvent comprising the liquid hydrocarbon mixture in this case will be described in detail.
The ratio of the aromatic hydrocarbon contained in this fractionation solvent is:
It is 5 to 70%, preferably 8 to 65%. When the proportion of the aromatic hydrocarbon exceeds the above range, a substantial amount of the different hydrocarbon-based plastic, particularly PVC, will be dissolved. On the other hand, when the proportion is less than the above range, the hydrocarbon-based plastic, particularly PS Substantially does not dissolve. The proportion of the paraffinic hydrocarbon is 5 to 85%, preferably 10 to 80%. When the proportion of the paraffin-based hydrocarbon exceeds the above range, the hydrocarbon-based plastic, particularly PS, substantially does not dissolve, while when the proportion is less than the range, the different hydrocarbon-based plastic,
In particular, a substantial amount of PVC becomes soluble. The proportion of the olefinic hydrocarbon in the mixture is the remaining amount obtained by subtracting the aromatic hydrocarbon and the paraffinic hydrocarbon in the mixture, and is usually 0 to 25%.

In the present specification, the proportions of the aromatic hydrocarbon, paraffinic hydrocarbon and olefinic hydrocarbon with respect to the fractionation solvent are different from the usual weight%,
It was determined based on a ¹³ C-NMR spectrum,
The apparatus for measuring the ¹³ C-NMR spectrum, the measurement conditions, the assignment of the spectrum, and the method for obtaining the ratio of each component are as follows.

(1) Apparatus The nuclear magnetic resonance spectroscopy (hereinafter referred to as NMR) apparatus used for the measurement is a GX270-FTNMR apparatus manufactured by JEOL Ltd. (2) Measurement conditions The sample was deuterated chloroform (CDCl ₃ : 99.96a manufactured by ISOTECINC.) As a solvent and an NMR lock agent.
dissolved in tom% D), 3 with respect to ¹³ C-NMR measurement
The concentration was 0 wt%. Chemical shift is 5 mmφ using tetramethylsilane (TMS) as an internal standard (0.0 ppm).
The measurement was performed at a rotation speed of 15 Hz using a Pyrex sample tube. The main measurement conditions are ¹³ C-NMR, ¹ H decoupling measurement with gate (NNE) eliminating nuclear Overhauser effect (NOE) for quantitative measurement.
Was performed, and the pulse repetition time was 6.9 seconds, the data point was 32 K, and the number of integrations was 4000. (3) Assignment of spectrum and determination of percentage of each hydrocarbon component ¹³ C-NMR spectrum is described in Eberhand, Breifmaier., And Wolfgang Voelter.
on-13 NMRSpectroscopy ”, VCH Verlagsgesellschaft
mbH, (1987), and the integrals were calculated to calculate the integrals of each bond type carbon (paraffin hydrocarbon: Cp, olefin hydrocarbon: Co, aromatic hydrocarbon: Ca). Percentages were determined. Chemical shift of paraffinic hydrocarbon (Cp): 14.2
46.2 ppm Chemical shift of olefinic hydrocarbon (Co): 111.
5-114.2 ppm, 137.0-145.0 ppm Chemical shift of aromatic hydrocarbon (Ca): 125.5-
136.9 ppm In the method of calculating the percentage of each hydrocarbon component based on the ¹³ C-NMR spectrum, the aromatic hydrocarbon having a paraffinic hydrocarbon group bonded thereto is composed of a paraffinic hydrocarbon and an aromatic hydrocarbon. The aromatic hydrocarbon to which the olefinic hydrocarbon group is bonded is calculated by dividing into an olefinic hydrocarbon and an aromatic hydrocarbon.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a schematic view of an apparatus for separating plastic waste (hereinafter, also simply referred to as waste) according to the present invention. FIG.
1 is a cylindrical airtight container, 2 is a container top plate, 3 is a container bottom plate, 4 is a container peripheral wall, 5 is a screw conveyor, 6 is a screw rotation shaft, 7 is a screw blade formed in a mesh structure, and 8 is a screw blade. Reference numeral 9 denotes a waste supply mechanism, 9 denotes an undissolved plastic discharge mechanism, 10 denotes a separation solvent supply pipe, 11 denotes a liquid spray nozzle, 12 denotes a plastic discharge pipe dissolved in the separation solvent, 13, 14 denotes a screw, and 15 denotes a screen.

FIG. 2 is an explanatory view of the structure of the screw conveyor. In FIG. 2, 5 indicates a screw conveyor,
Reference numeral 6 denotes a rotation axis, and reference numeral 7 denotes a screw blade formed in a mesh structure. A plate A is provided at the peripheral end of the screw blade 7.
However, this is not always required. This plate A can also be formed in a mesh structure. When the screw conveyor 5 is rotated in the direction of the arrow and waste is supplied onto the screw blade, the waste is pushed up by the screw blade and moves upward.

In the apparatus shown in FIG. 1, the portion consisting of the screw conveyor 5 in the container forms a solid-liquid contact zone, and the bottom of the container forms a plastic storage zone dissolved in a fractionating solvent. The waste supply mechanism 8 may have any structure as long as it can supply waste into the container, but a supply pipe having an internal screw structure is usually used. The undissolved plastic discharging mechanism 9 may have any structure as long as it can discharge the undissolved plastic to the outside of the container. Usually, a discharge pipe having a screw structure inside is used. In the present invention, it is particularly preferable to use a discharge pipe whose inside has a screw structure whose inner diameter decreases toward the distal end. In such a discharge pipe, since the undissolved plastic is compressed in the discharge pipe, the fractionated solvent adhering to the surface of the undissolved plastic is squeezed out in the container direction, and is sent back into the container. The portion of the separation solvent supply pipe 10 located inside the container is preferably formed in a liquid dispersion structure. FIG. 1 shows an example of a structure in which a liquid spray nozzle 11 is attached to a pipe, but in the case of the present invention, the present invention is not limited to such a structure. And a structure in which a plurality of thin tubes are connected to a pipe wall of a pipe. The screen 15 functions to prevent the supplied plastic waste from falling down and to feed the supplied plastic waste onto the screw blade 7. In the case of the present invention, a perforated plate can be used instead of the screen 15.

In order to separate waste using the separation apparatus shown in FIG. 1, the screw conveyor 5 is rotated via a rotating shaft 6 and the waste is supplied from a supply mechanism 8 thereof.
The fractionated solvent is fed through the supply pipe 10 and the liquid spray nozzle 11 above or above the solid-liquid contact zone, i.e., on the screw blades below the solid-liquid contact zone, i.e., below the screw conveyor. The fractionated solvent passes through the waste on the screw blades and further down through the mesh of the screw blades. The waste supplied on the screw blades of the screw conveyor moves upward due to the rotation of the screw conveyor, but comes into countercurrent contact with the separation solvent flowing down while moving upward, and part of the waste is separated. Dissolves selectively in solvents. The concentration of the plastic component dissolved in the separation solvent flowing down the solid-liquid contact zone gradually increases from the top to the bottom of the solid-liquid contact zone, and the concentration in the separation solvent at the lower end of the solid-liquid contact zone Is the largest. The plastic dissolved in the fractionated solvent that has passed through the solid-liquid contact zone is stored in the storage zone at the bottom of the container, and is discharged through the discharge pipe 12. In this case, the storage zone is not necessarily required, and the plastic dissolved in the separation solvent can be directly discharged to the outside from the lower part of the solid-liquid contact zone through the discharge pipe.

The contact temperature between the waste and the fractionation solvent in the solid-liquid contact zone is the temperature at which the soluble plastic dissolves in the fractionation solvent, and usually heating conditions are employed. For example,
When the waste consists of a hydrocarbon plastic and a different hydrocarbon plastic, the contact temperature is 50 to 200.
° C, preferably 80 to 180 ° C. The pressure in the container is
Under the heating conditions, the pressure may be a pressure sufficient to maintain at least a part of the fractionated solvent in a liquid phase.
cm ² G, preferably 0 to ² kg / cm ² G. The contact time is a time required for the plastic to dissolve, and is usually 1 minute or more, preferably 3 to 30 minutes. The usage ratio of the fractionated solvent is 50 to 50 parts by weight of the waste.
The proportion is 1000 parts by weight, preferably 100 to 500 parts by weight. The concentration of the plastic dissolved in the fractionation solvent obtained from the solid-liquid contact zone in the solution is 5 to 50% by weight, preferably 10 to 40% by weight. The concentration of the dissolved plastic can be adjusted by the supply amount of the fractionating solvent.

According to the separation processing of the present invention as described above,
The plastic insoluble in the separation solvent is separated from the plastic soluble in the separation solvent, discharged to the outside through the discharge mechanism 9, and collected. Even if components other than plastic (paper, cloth, aluminum foil, metal fragments, earth and sand, etc.) are mixed in the waste, these components are also separated from the soluble plastic and discharged to the outside through the discharge mechanism 9. . According to the separation process of the present invention as described above, the undissolved plastic is in contact with the separation solvent containing no dissolved plastic in the upper part of the solid-liquid contact zone, and the dissolved plastic adhering to the surface thereof becomes the separation solvent. After being dissolved and removed, it is discharged outside. Therefore, in the case of the present invention, the loss of the melted plastic can be effectively prevented, and the discharged unmelted plastic is easy to handle without surface tackiness.

[0016]

Next, the present invention will be described in more detail with reference to examples.

Reference Example 1 As a plastic waste model, PE: 35% by weight,
A plastic mixture consisting of 30% by weight of PP, 20% by weight of PS, 5% by weight of PVC, 5% by weight of PET and 5% by weight of ABS resin was crushed into strips. Next, Table 1
10 g of the crushed material was added to 100 g of each of the various solvents shown in (1) and heated at 130 ° C. for 30 minutes with stirring to conduct a plastic dissolution test. Table 2 shows the results. In Table 2, when the plastic component was dissolved in the solvent, it was indicated by "O", and when it was not dissolved, it was indicated by "X".

The specific contents of the pyrolysis oil shown in Table 1 are as follows. Pyrolysis oil A: Pyrolysis oil of PE Pyrolysis oil B: Mixed oil of pyrolysis oil of PS and pyrolysis oil of PE (mixing weight ratio = 0.95 / 0.05) Pyrolysis oil C: PE Mixed oil of pyrolyzed oil, pyrolyzed oil of PP and pyrolyzed oil of PS (mixing weight ratio = 1/1/1) Pyrolyzed oil D: Fraction of boiling point of pyrolyzed oil of PE below 280 ° C Oil E: a fraction having a boiling point of 150 to 350 ° C. of pyrolysis oil C Pyrolysis oil F: a fraction having a boiling point of 280 ° C. or lower of pyrolysis oil C Pyrolysis oil G: A fraction having a boiling point of 280 ° C. or lower of pyrolysis oil of PE Oil of a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PP and a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PS (mixing weight ratio = 8/8/84) A mixed oil of a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil, a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PP, and a fraction having a boiling point of 280 ° C. or less of the pyrolysis oil of PS (Weight ratio = 44/45/11)

[0019]

[Table 1]

[0020]

[Table 2]

The following can be seen from the results shown in Table 1 above. (1) Xylene is at least one kind of plastic A selected from PE, PP, PS and ABS, and PVC
It can be used as a separation solvent for selectively dissolving the plastic A contained in the waste consisting of at least one kind of plastic B selected from PET and PET. (2) Toluene is at least one kind of plastic A selected from PS and ABS, and PE, PP, PVC
It can be used as a separation solvent for selectively dissolving the plastic A contained in the waste consisting of at least one kind of plastic B selected from PET and PET. (3) Pyrolysis oil A comprises at least one kind of plastic A selected from PE and PP, and PS, PVC, PE
It can be used as a fractionation solvent for selectively dissolving the plastic A contained in the waste consisting of at least one type of plastic B selected from T and ABS. (4) Pyrolysis oil D comprises at least one kind of plastic A selected from PE and PP, and PS, PVC, PE
It can be used as a fractionation solvent for selectively dissolving the plastic A contained in the waste consisting of at least one type of plastic B selected from T and ABS. (5) Pyrolysis oils B, C, EH are PE, PT and PS
At least one kind of plastic A selected from
It can be used as a fractionation solvent for selectively dissolving the plastic A contained therein from the waste consisting of at least one type of plastic B selected from PVC, PET and ABS. That is, these pyrolysis oils are suitable as a separation solvent for separating waste consisting of hydrocarbon plastics and different hydrocarbon plastics into these two components.

Reference Example 2 A hydrocarbon-based plastic mixture (PE: 41% by weight, PP: 35) among the plastic mixtures shown in Reference Example 1
(% By weight, PS: 24% by weight) was dissolved in 100 g of the solvent F to form a solution, and this solution was thermally decomposed at 400 ° C. and normal pressure to obtain a cracked oil. next,
The cracked oil was distilled to obtain a fraction A having a boiling point of 100 to 400 ° C. Next, a dissolution test of the plastic mixture was performed in the same manner as in Reference Example 1 except that this fraction A was used as a fractionating solvent. As a result, it was confirmed that PE, PP and PS were all dissolved. In addition, it was confirmed that PVC, PET, and ABS resin were substantially insoluble and retained solid in the solvent. Further, when the proportions of aromatic hydrocarbons, paraffinic hydrocarbons and olefinic hydrocarbons contained in the fraction A were examined based on the ¹³ C-NMR spectrum, it was found that aromatic hydrocarbons: 3
The results were 5%, 50% paraffinic hydrocarbons and 15% olefinic hydrocarbons.

Example 1 A pulverized product of the plastic mixture shown as a plastic waste model in Reference Example 1 was treated according to the following steps. (1) Separation Step Using the fraction A shown in Reference Example 2 as a separation solvent, a separation operation was performed using a separation apparatus having a structure shown in FIG. In this case, the contact temperature between the raw material plastic mixture and the fraction A is 130 ° C., and the pressure in the apparatus is normal pressure. The contact time is 30 minutes and the amount of the raw plastic mixture used is 1
The amount of the fraction A was 300 parts by weight. 385 parts of a solution obtained by dissolving the hydrocarbon-based plastic in the fraction A at a concentration of about 22% by weight,
15 parts by weight of undissolved solid hetero-hydrocarbon plastic was obtained. (2) Decomposition Step 100 parts by weight of the solution containing the hydrocarbon-based plastic obtained in the separation step was thermally decomposed at 400 ° C. and normal pressure for 30 minutes to obtain 98 parts by weight of a decomposition product oil. (3) Fractionation fractionation step for fractionated solvent The cracked product oil obtained in the cracking step is distilled and has a boiling point of 400 ° C.
The above heavy oil fraction was separated into 0.7 parts by weight and a light oil fraction having a boiling point of 150 ° C. or lower 5.4 parts by weight. The light oil fraction thus obtained was analyzed by ¹³ C-NMR for the composition of the light oil fraction.
It was composed of 50% paraffinic hydrocarbon and 15% olefinic hydrocarbon. Using this light oil fraction as a fractionating solvent, the plastic mixture was dissolved in the same manner as in the above-mentioned dissolving step. However, it was confirmed that it was kept in a solid state.

[0024]

The method and apparatus for separating plastic waste according to the present invention can continuously and efficiently separate a plastic component soluble in a separation solvent and a plastic component insoluble in the separation solvent. Moreover, in the case of the present invention,
Since the dissolved plastic component does not substantially adhere to the plastic component that is insoluble in the separation solvent, loss of the dissolved plastic component during the separation of the dissolved plastic component and the insoluble plastic component can be effectively prevented. In addition, the obtained plastic component insoluble in the fractionating solvent has no surface tackiness and is very easy to handle because there is no adhesion of the dissolved plastic component to the surface.

[Brief description of the drawings]

FIG. 1 is a schematic view of a plastic waste sorting apparatus according to the present invention.

FIG. 2 shows an explanatory structural view of a screw conveyor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Plastic waste separation apparatus 5 Screw conveyor 6 Rotating shaft 7 Screw blade 8 Plastic waste supply mechanism 9 Undissolved plastic discharge mechanism 10 Separation solvent supply pipe 11 Liquid spray nozzle 12 Hydrocarbon plastic discharge pipe dissolved in separation solvent 13, 14 Screw

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location // B29K 105: 26 (72) Inventor Takashi Kimura 2--12 Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1 Inside Chiyoda Chemical Works, Ltd. (72) Inventor Kenji Nomi 2-2-1, Tsurumi Chuo, Tsurumi-ku, Yokohama, Kanagawa Prefecture No. 1 Inside Chiyoda Chemical Works, Ltd.

Claims (2)

[Claims] 1. A method for separating plastic waste, comprising: (i) feeding the waste to a lower part of a solid-liquid contact zone comprising a screw conveyor having screw blades formed in a mesh structure, and moving the waste upward; (Ii) supplying a fractionated solvent from above or above the solid-liquid contact zone, contacting the waste with the waste, and dissolving a part of the plastic contained in the waste; (iii) Recovering the undissolved plastic from the upper part of the solid-liquid contact zone; and (iv) recovering the plastic dissolved in the separation solvent from the lower part of the solid-liquid contact zone. . 2. An apparatus for separating plastic waste using a separation solvent, wherein (i) the whole is formed in a cylindrical closed container, and (ii) the waste is placed inside the container from below. The screw blade to be moved has a solid-liquid contact zone composed of a screw conveyor formed in a mesh structure, and (iii) a supply mechanism for supplying the waste to a lower portion of the solid-liquid contact zone at a lower portion of the container. (Iv) having a discharge mechanism at the top of the container for discharging the plastic not dissolved in the separation solvent, and (v) the separation solvent at the top or top of the container at the top of the solid-liquid contact zone. Or a supply pipe for supplying the plastic waste upward.