JPH1112389A - Classification and treatment of mixed waste plastics with solvent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for classifying and treating mixed waste plastics with a mixed waste plastic solvent obtained by thermally decomposing the mixed waste plastics. SOLUTION: This method for classifying and treating mixed waste plastics with a mixed waste plastic solvent comprises fractionating the thermal decomposition production oil of the waste plastics (mainly a polyolefin, a sytrenic polymer or their mixture) into a light oil and a heavy oil, treating the mixed waste plastics (PE, PP, PS, PVC or PET) or laminated films (mixed waste plastics, aluminate or paper) with the obtained light oil as a solvent to classify the mixed waste plastics into plastics (PE, PP, PS) suitable for thermal decomposition oil production and plastics (PVC, PET) unsuitable for the oil production, separating PVC with a solvent dissolving the PVC, and finally mechanically separating the left paper, aluminum and PET from each other.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to PE, PP, PS, PVC, PE discharged from households, factories, supermarkets and the like.
The present invention relates to an oil-forming and solid-fueling apparatus that effectively utilizes waste plastic (composite material) containing T, aluminum, and paper.

[0002]

2. Description of the Related Art When vinyl chloride is contained in mixed waste plastics, the separation method is as follows: 1) Gravity separation (in a water tank) 2) Utilizing the absorption of X-rays by chlorine atoms in PVC I
R method 3) Solvent method (tetrahydrofuran, methyl isobutyl ketone) 4) Wind separation 1), 2) and 4) cannot be completely separated, so they are partly mixed in the oiling process and are expensive extruders to process them And a melting tank for dehydrochlorination (desalting rate: about 90 WT%). PET bottles are collected and sorted, but since PET resin is used everywhere other than the bottles, some of them are mixed into the oiling process, so that treatment can be performed even in the oiling process. For composite films, mechanical separation is mainly used, and milk packs are chemically separated using caustic soda. The solvent is recovered by a thin film evaporation method and a heating vacuum method.

[0003]

However, the above method has the following problems. 1) When the mixed waste plastic is liquefied, if PVC is contained, it causes corrosion of the equipment and contains many organic chlorine compounds, so that it cannot be a product. At present, about 90 WT% dehydrochlorination is carried out before an oil extruder is installed with an expensive extruder and a melting tank, but it is not economical and reliable. High hydrochloric acid recovery cost. 2) When PET is mixed into the oiling device, PET is 300 ° C.
Sublimates to precipitate and block the terephthalic acid crystal by pipes and the like, and the quality is adversely affected by the inclusion of the crystal in the produced oil. It also reduces the oiling rate. 3) Burning oil containing PVC and organochlorine compounds generates highly toxic dioxins. Currently, solid fuels exclude PVC. 4) The cost of crushing and foreign matter separation is high because wind power and gravity separation crush finely. In particular, gravity separation (although the separation efficiency is high) uses water, so that drying and wastewater treatment are costly. 5) The X-ray method is effective for bottles, but is difficult for films. 6) Conventional solvents have high solvent costs and are not economical. 7) The mechanical method of separating plastic, aluminum, and paper from the composite film is expensive, and milk packs use caustic soda, so wastewater treatment is required, and the separation time is 3 hours, which is inefficient. 8) The simplest, low-cost, and high-impact incineration of these composite films is currently the mainstream.

[0004]

[Means for Solving the Problem] Waste plastics (polyolefin and styrene-based plastics are mainly used alone or in combination) are thermally decomposed (temperature about 400 ° C., reaction time about 4 hours).
Time) and convert the resulting pyrolysis oil to light oil (boiling point of about 16
0 ° C) and separated into heavy oils, and light oils are used as solvents.

When a mixed plastic containing PVC and PET and this solvent are mixed and contacted in a solution at about 120 ° C., PE,
Only PP and PS resins are dissolved, and PVC and PET do not dissolve and remain as a solid. The dissolved PE, PP, and PS pass through the strainer and become an oil material. Undissolved PVC,
PET is caught by a strainer.

[0007] PE, PP and PS are thermally decomposed in a pyrolysis tank, separated into light oil and heavy oil by simple distillation, and the light oil is used again as a solvent. Undissolved PVC and PET are PVC
And a solvent exhibiting excellent solubility (solvent having a solubility parameter close to the solubility parameter, such as EDC, MEK, dioxane, etc.) and separated from undissolved PET. A solution of PVC is separated into PVC and a solvent by a heating vacuum method or the like, and the solvent is separated and reused, and PVC is recovered as a recycled resin raw material.

[0008] Composite films and milk packs are also treated under the same conditions using the present solvent (solvent that dissolves pyrolytic light oil and PVC), so that PE, PP, and PS can be converted to oily raw materials by PVC.
Aluminum, paper and PET are mechanically separated as recycled resin raw materials. By doing so, both PET and recycled resin material can be used as recycled aluminum.

[0009]

According to the present invention, the following effects can be obtained. 1) The solvent (pyrolysis light oil) is very economical because it is obtained from pyrolysis of waste plastic. 2) If waste plastic containing PVC and PET, which are unsuitable as pyrolysis oil conversion raw materials, is treated by this method, pretreatment equipment and oil conversion equipment (expensive extruder for dehydrochlorination, etc. can be eliminated) are simplified and heat is reduced. The economics and reliability of cracking oil are greatly improved. 3) Even if PVC and PET are mixed in the waste plastic, if this method is adopted, a high-quality product can be obtained without the organic chlorine compound and terephthalic acid crystal in the pyrolysis oil. 4) The solvent (pyrolyzed light oil) can be widely used for separating composite materials such as composite films and milk packs. It can also be used for solid fuel production. 5) If a solvent that dissolves PVC is used for separation of PVC and PET, recycled PVC and PET raw materials and recycled aluminum can be obtained. 6) If the present invention is practiced, the separation of the composite material, which has been conventionally difficult, becomes economical, and the recycle rate of waste plastic rises sharply.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an apparatus suitable for carrying out the method of the present invention. Waste plastic (PE, P
P, PS, PVC, PET, aluminum, paper)
The mixture is crushed to about 5 cm at 0 and charged into a dissolution tank 102 using a charging machine 101. Dissolution tank 1 provided with stirrer 103
02, the pyrolysis light oil (solvent) heated to about 120 ° C. is filled to about 60% of the dissolution tank capacity. In the dissolving tank, PE, PP, and PS are selectively dissolved while the solvent and the waste plastic are stirred and mixed to remove water, and PVC, PET, aluminum, and paper are not dissolved at all. These solutions are processed by a strainer 104 with a spare provided at the bottom of the dissolution tank. The dissolved PE, PP, and PS pass through the strainer and are inserted into the thermal decomposition tank 007 via the pump 006. Undissolved PVC, PET, aluminum and paper are caught by the strainer. PE, P stuck in pyrolysis tank 007
By giving P and PS at a temperature of about 400 ° C. for a reaction time of about 4 hours, a certain amount of P and PS is separated from the pyrolysis oil and the residue from the bottom of the pyrolysis tank. The thermally cracked oil is separated into light oil (solvent) and heavy oil by simple distillation or the like while exchanging heat, and is stocked in the light oil tank 009 and the heavy oil tank 012. Light oil (solvent) is partially supplied to the heater 01 via the light oil pump 010.
In step 1, the mixture is heated to a temperature of about 120 ° C. and stuck into the melting tank.
The remaining light oil becomes a product. A part of heavy oil and cracked gas are used as fuel, and the remaining heavy oil becomes a product. PVC,
The separation of PET is carried out by dissolving in PVC, for example EDC, M
EK, dioxane or the like is used as a solvent. Dissolved P
VC is introduced into a heating vacuum apparatus, separated into a solvent and PVC, and cyclohexane as a solvent is reused. PVC resin is used as a resin material for regeneration. Composite films, milk packs and the like are treated in the same manner, but the separation of aluminum, paper and PET is mechanically separated.

[Brief description of the drawings]

FIG. 1 shows a preferred embodiment for treating a mixed waste plastic of PE, PP, PS, PVC, PET, aluminum and paper.

[Explanation of symbols]

REFERENCE SIGNS LIST 100 Crusher 117 Aluminum / paper / PET separator 101 Feeder 102 Dissolution tank 103 Stirrer 104 Strainer 105 Thermal decomposition tank feed pump 106 Thermal decomposition tank 107 Heat exchanger / Distillation device 108 Light oil tank 109 Light oil pump 110 Heater 111 Heavy Oil tank 112 Heavy oil pump 113 PVC dissolving tank 114 Strainer (catch such as PET) 115 Dissolved PVC transfer pump 116 Heating vacuum device (PVC solvent recovery)

Claims (3)

[Claims] 1. A mixed waste plastic, ie, polyethylene (P), using light oil as a solvent among waste plastic pyrolysis oils.
E), polypropylene (PP), polystyrene (P
S), vinyl chloride (PVC), polyethylene terephthalate (PET) and PE, PP, PS dissolved in this solvent by contacting this solvent at about 120 ° C
C and PET are separated by a strainer. 2. Separation of PVC and PET uses a solvent which is soluble in PVC (select a solvent having a solubility parameter close to the solubility parameter). The solvent is recovered by a heating vacuum method or the like, and the PVC separated at that time is reused as a recycled resin material. 3. A mixture of PE, PP, PS and PVC, PET, aluminum, and paper are separated from a composite film, a milk pack, etc. by using the same solvent (solvent that dissolves pyrolysis light oil and PVC). .