JP2000127165A - Method for separating waste plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate a chlorine-containing plastic such as PVC or the like from a film-like plastic and to further separate the other waste plastic. SOLUTION: A film-like waste plastic is roughly comminuted by a primary comminutor 1 and then cooled to a low temperature of a low temperature range (-40 to -20 deg.C) of an embrittle temperature of -20 deg.C of a PVC or the like to -40 deg.C of an embrittle temperature of the other waste plastic by a cooler 2. Then, the plastic is comminuted to a size of about 15 mm by a secondary comminutor 3. The brittle comminuted PVC or the like is reduced as compared with the other waste plastic. Then, the plastic is raised to an ambient temperature by a heater 4, introduced into a dry separator 5, and separated into a polyethylene, a polypropylene, a polystyrene and the like 7, paper 8 not brittle comminuted according to the dry separation, PVC or the like 9 and the other waste plastic 10 of substantially the same size as that of the PVC 9 brittle comminuted according to the dry separation. The PVC or the like 9 and the other waste plastic 10 are further introduced into a wet separator 6, and separated to the PVC or the like 9 of a heavy specific gravity side and the other waste plastic 10 of a light specific gravity side according to a wet separation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently separating chlorine-containing plastics from film-like waste plastics in general waste.

[0002]

2. Description of the Related Art Film-like plastic waste, which accounts for the majority of general waste, includes chlorine-containing plastics such as polyvinyl chloride (PVC) and polyvinylidene chloride (P).
VDC) and the like are mixed in at about 10%. In the treatment measures, if incinerated as it is, toxic gas is discharged due to chlorine-containing plastics. In addition, when blowing into a blast furnace, the allowable content of chlorine-containing plastics must be 1% or less. And cannot be reused. In landfill, a large land area is required due to the large floor area ratio.

[0003]

As a means for separating plastics, wet specific gravity separation is known. However, since the film-like plastic has a small apparent bulk density, even if it is separated by wet specific gravity separation, the processing amount is small. Further, the separation efficiency is poor due to the adhesion of bubbles. When a centrifugal specific gravity separator is used as the wet specific gravity separator, the separation efficiency is high, but the device is expensive.

On the other hand, air tables and air jigs which are dry separations have a large shape effect, so that a film plastic having a large specific gravity and a small film plastic having a low specific gravity have poor separation efficiency.

Accordingly, an object of the present invention is to separate film-like waste plastics contained in general wastes.
An object of the present invention is to solve the above-mentioned problems and to provide a method capable of efficiently separating chlorine-containing plastics and other various kinds of plastics by combining dry separation and wet separation.

[0006]

According to the first aspect of the present invention,
Waste film plastic containing paper mixed with -20
° C to a low temperature range of -40 ° C or higher to make the chlorine-containing plastic brittle, then crush the paper and film waste plastic in the low temperature range, and then crush the crushed paper and film waste. The plastic is heated to a temperature at which moisture does not adhere, and then the heated paper and film-like waste plastic is dry-separated by brittle crushed chlorine-containing plastic and other waste plastics of approximately the same size as said chlorine-containing plastic. And, it is separated into waste plastics and papers, such as polyethylene, polypropylene and polystyrene, which are not brittle and larger than the chlorine-containing plastics, and then wet-separated to have the same size as the chlorine-containing plastics and the chlorine-containing plastics. Update with other waste plastics It is characterized in that it separates film-based mixed waste plastics containing paper with the embrittlement temperature of chlorine-containing plastics of -20 ° C or lower, and the embrittlement temperature of other waste plastics. There is -4
By cooling to a temperature range of 0 ° C. or higher (−20 to −40 ° C.) and performing cooling in this low temperature range, only the brittle chlorine-containing plastic is finely crushed (brittle crushing). Since this crushed mixture is cooled, if the next dry separation is performed as it is, the crushed mixture contains moisture and the films adhere to each other with moisture. In order to avoid this, for example, the temperature is raised to room temperature so as not to be humidified by heating or nitrogen purge. Thereafter, dry separation is performed by an air table or an air jig. As a result, relatively large films of polyethylene, polypropylene, polystyrene (polyethylene, polypropylene and polystyrene are not brittle and crushed) and paper mixed in mixed plastics, and brittle and finely crushed chlorine-containing plastics and crushed As a result, it is separated into chlorine-containing plastic and other waste plastics of approximately the same size. Thereafter, the mixture of the chlorine-containing plastic and the other waste plastic is further separated by wet separation such as centrifugal specific gravity separation.

[0007] In dry separation, chlorine-containing plastics are broken into smaller pieces due to brittle fracture.
It can be separated from other large film-like waste plastics such as polyethylene, polypropylene and polystyrene with high efficiency.

[0008] Although a wet separation apparatus such as a centrifugal specific gravity separation apparatus is expensive, according to the present invention, only chlorine-containing plastics which have been embrittled and finely crushed and other waste plastics having a size substantially the same as the chlorine-containing plastics are used. Is fed into the wet separation device. Therefore, the input amount to the wet separation device is reduced to 50% or less of the total waste plastic. Accordingly, the number of water treatment facilities required for wet separation is reduced.

Further, if a large film-shaped waste plastic enters the wet separation apparatus, it causes blockage of the apparatus and lowers the separation efficiency. In the present invention, the large waste plastic film is separated by the dry separation before the wet separation step, so that the processing efficiency of the wet separation can be greatly improved and the processing amount can be increased.

[0010]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a device configuration according to an embodiment of the present invention.

Paper is mixed in film-like waste plastic in general waste. The mixed waste plastic with which the paper is mixed is roughly crushed by the primary crusher 1. Next, by the cooler 2, a low temperature range (−40 to −20 ° C.) from −20 ° C. or less, which is the brittleness temperature of the chlorine-containing plastic, to −40 ° C. or more, which is the brittleness temperature of polystyrene.
Is cooled. In the present embodiment, the cooling temperature is −30 ° C.
And Next, the cooled paper-mixed waste plastic is crushed by the secondary crusher 3 to a size of about 15 mm. At this time, the chlorine-containing plastic has become brittle and has been brittlely crushed by the secondary crusher 3 and has become smaller than other waste plastics. Next, the crushed paper-mixed waste plastic is heated to room temperature (about 20 ° C.) by the heating heater 4. Then, it is put into the air table type separation device 5 and is made of polyethylene, polypropylene, polystyrene 7 and paper 8 which are not brittle and crushed by dry separation, and the brittle crushed chlorine-containing plastic 9 and the same diameter as the chlorine-containing plastic due to crushing and the like. It is separated from other waste plastics 10.

The chlorine-containing plastic 9 and other waste plastics 10 are further fed into a centrifugal specific gravity separator 6 and separated into light specific gravity waste plastics and heavy specific gravity waste plastics by wet separation. By setting a chlorine-containing plastic such as PVC as a heavy-gravity-side waste plastic to be separated, the chlorine-containing plastic 9 and other waste plastics 10 can be separated.

[0013]

As described above, according to the present invention, the following useful effects can be obtained in the separation of waste plastic film. (1) The size of chlorine-containing plastic can be made smaller than that of other waste plastics having different embrittlement temperatures by brittle fracture after cooling at a low temperature below the embrittlement temperature, and the separation efficiency by dry separation is improved. . (2) Since only chlorine-containing plastic and other waste plastics of almost the same size are fed into the wet separation device by dry separation, the input amount is about 50% of the total waste plastic, and the throughput of wet separation is reduced. It is possible to reduce the number of water treatment facilities required for the wet separation and reduce the number of expensive wet separation devices. Also,
Since large film waste plastic does not enter the wet separation device by the dry separation, clogging and failure of the wet separation device are avoided. (3) By separating the chlorine-containing plastic mixed in the waste plastic with high efficiency, a plastic mixture having a chlorine-containing plastic content below the allowable value can be obtained and reused as a raw material for blowing into a blast furnace. Can be offered. (4) The amount of waste landfilled can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a device configuration according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Primary crusher 2 Cooler 3 Secondary crusher 4 Heating / heating machine 5 Air table type separation device 6 Centrifugal specific gravity separation device 7 Waste plastic such as polyethylene, polypropylene, polystyrene, etc. 8 Paper 9 Chlorine-containing plastic 10 Almost the same as chlorine-containing plastic Other waste plastics of the same size

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) // B29K 27:06 105: 26 (72) Inventor Iwa ▲ Saki ▼ Toshihiko 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Nippon Steel Pipe Co., Ltd. BA01 BA21 BA29 BF08 BF09 BF13 BF31

Claims (1)

[Claims] 1. A film-like waste plastic mixed with paper is cooled to a low temperature range of −20 ° C. or lower to −40 ° C. or higher to embrittle the chlorine-containing plastic, and then the paper and the film-like waste plastic are cooled. Crushed in the low temperature range, then heated the crushed paper and film waste plastic to a temperature at which moisture does not adhere,
Then, the heated paper and film-like waste plastics are dry-separated by brittle crushed chlorine-containing plastics and other waste plastics having substantially the same size as the chlorine-containing plastics, and are not brittlely crushed and are not more than the chlorine-containing plastics. Separation into waste plastics such as polyethylene, polypropylene and polystyrene and papers, and then further separation by wet separation of chlorine-containing plastics and other waste plastics of substantially the same size as the chlorine-containing plastics. Waste plastic separation method.