JPH0753766A - Method for separating foreign matter from plastic waste - Google Patents

Abstract

PURPOSE:To separate foreign matters from a plastic waste by melting it and discharging the foreign matters through the upper outlet port of an extruder having a screw shaft inclined upward in the direction of extrusion. CONSTITUTION:A plastic waste contg. foreign matters is melted or dissolved in a solvent without separating by hand. The melt or soln. is fed to an extruder having a screw shaft inclined upward in the direction of extrusion and conveyed upward by the screw, separating solid foreign matters from the melt or soln. during the conveyance and discharging them through the upper outlet port. When the waste is melted, it is kept at the melt temperature at least in the solid-liq. separation zone of the extruder. When a foamed polystyrene waste is treated, dissolving it in styrene as the solvent is advantageous.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating foreign matter from plastic waste containing foreign matter.

[0002]

2. Description of the Related Art At present, the amount of plastic waste is increasing, and now it is becoming a problem on a global scale.

Other foreign substances are inevitably mixed in the plastic waste. The processing is relatively easy if only plastic is used, but if foreign substances are mixed, this sorting and separation is troublesome.

It is economically unprofitable if the waste is manually separated and separated. The point of plastic waste treatment is how to efficiently collect and dispose of only plastic from a huge amount of waste. This problem cannot be avoided whether the waste plastic is oiled or reused. No effective treatment method has yet been established for this sort separation.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method for efficiently separating a plastic component from a plastic waste containing a foreign substance.

[0006]

Means for Solving the Problems The above problems can be solved by the following means.

[1] Selectively melt and liquefy the resin component of plastic waste mixed with foreign substances and liquefy it with a solvent, and push it up from the bottom of the inclined extruder to transfer the liquefied component to the bottom. A method for separating foreign matter from plastic waste, characterized in that the solid foreign matter is made to flow down to the solid waste fluid and the remaining solid foreign matter is pushed up by a transfer element to separate solid and liquid from each other.

[2] After selectively melting and liquefying the resin component of the plastic waste mixed with foreign matter or dissolving and liquefying with a solvent,
A method for separating foreign matter from plastic waste, which comprises centrifuging the solid foreign matter.

[0007]

When the liquefied resin is passed through an inclined extruder (screw conveyor), it is not transferred to the upper side even if the screw rotates, but drops downward. On the other hand, solid foreign matter is pushed up and transferred by the rotation of the screw. The present invention utilizes this property of liquid and solid to separate solid and liquid. There are the following two methods of liquefying the resin. 1. Although there are some differences depending on the melting method type, the resin is approximately 300 to 5
At a temperature of 00 ° C, it becomes a free-flowing liquid like water.
Foreign substances other than resin are almost solid at this temperature. The solid-liquid is separated by utilizing this property of the resin and the foreign matter other than the resin. The extruder used in the present method needs to be kept at the liquefaction temperature of the resin at least in the area for separating the solid and liquid, but it is not always necessary to keep the temperature at this temperature. For example, the temperature may be gradually increased from the inlet side to have a slope so as to reach the liquefaction temperature. A discharge port for discharging solid foreign matter is provided at the upper end. 2. Dissolution method Resin dissolves in organic solvent. When a solvent is sprinkled on the resin containing foreign substances, the resin dissolves and accumulates underneath. Foreign matter that does not dissolve in the solvent remains as a residue. The type of solvent is
It depends on the type of resin. For example, when the resin is styrofoam, acetone, toluene, a styrene monomer solution and the like are suitable, and a styrene monomer solution is particularly preferable. Styrofoam foams into the styrene monomer solution and dissolves violently. In the case of Styrofoam, the melting method is more suitable than the melting method.

[0008]

【Example】

Example 1 This was carried out with the apparatus shown in FIG. The extruder is tilted at an angle of 30 °. Various miscellaneous plastic wastes such as styrene, polyethylene, ABS, urethane, etc. are mixed with metal pieces, wood pieces, and rice cake residues as foreign matter, and then press-fit from the extruder inlet (1). Then, the transfer element (2) was transferred from the bottom to the top. The extruder was heated with a temperature gradient from the inlet to the central portion, and was heated to a temperature of 450 ° C. from the central portion to the outlet (3). When the nozzle of the take-out port (4) provided at the bottom of the extruder was opened, the liquid resin which was silky flowed out. Then, solid foreign matter was pushed out from the discharge port. Further, the vaporized plastic gas could be taken out from the gas vent (5). Example 2 This was carried out with the apparatus shown in FIG. The extruder tilt angle is 30 °
As the waste plastic, styrene foam tray waste with rice grains attached was used. After crushing the waste finely,
The resin component was dissolved by mixing with the styrene monomer solution and charged from the inlet (1) of the extruder. Solid rice grains were extruded from the discharge port (3), and liquid styrene dissolved in the styrene monomer solution flowed out from the discharge port (4). Example 3 As the waste plastic, the styrofoam waste mixed with the styrene monomer solution was used as in Example 2. It was possible to separate the mixture into a liquid styrene component dissolved in a styrene monomer solution and a solid rice grain by applying a rapid-centric separator.

[0009]

As described above in detail, the present invention is characterized in that plastic waste containing foreign matter can be separated into plastic and non-plastic parts without human intervention. It makes a great contribution to automation.

[Brief description of drawings]

FIG. 1 is an explanatory view of a melting method of the present invention.

FIG. 2 is an explanatory view of the dissolution method of the present invention.

[Explanation of symbols]

 (1) …… Extruder inlet (2) …… Transfer element (3) …… Ejecting port (4) …… Ejecting port (5) …… Gas venting

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Claims (2)

[Claims] 1. A liquefied component is lowered by selectively melting and liquefying a resin component of a plastic waste mixed with a foreign substance and liquefying it with a solvent and transferring the liquefied component from the bottom to the top in an inclined extruder. A method for separating foreign matter from plastic waste, characterized in that the remaining solid foreign matter is made to flow down to and the remaining solid foreign matter is pushed up by a transfer element to separate solid and liquid from each other. 2. A method for separating foreign matter from a plastic waste, which comprises selectively melting and liquefying a resin component of a plastic waste containing foreign matter and liquefying it with a solvent, and then centrifuging the solid foreign matter. .