JP2001219425A - Method for separating plastic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate a chlorine-containing plastic in a waste plastic. SOLUTION: The waste plastic 11 is crushed by a crusher 1, the crushed plastic is introduced into a melting and granulating unit 2, which melts and granulates the crushed plastic. Its melting temperature is set to lower than melting temperatures of a PVC and a PVDC to a melting temperature or higher of a PP. Thus, a plastic (non-chlorine-containing plastic) such as a PE, the PP or the like is melted and granulated. Meanwhile, the PVC and the PVDC (chlorine-containing plastic) is not melted, but retained in its shape as it is. These mixtures 11a are discharged from a melting and granulating machine 2, and introduced into a dry gravity shape separator 3. The mixtures 11a are separated by the separator 3 into a granulated material 11b and a non- granulated material 11c. The PE or PP material 11b thus obtained is recycled as an RDF or the like used for blowing through a blast furnace or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a plastic containing waste such as PVC (polyvinyl chloride) and PVDC (polyvinylidene chloride) (hereinafter referred to as PVC and PVDC) from plastic waste in general and industrial waste. (Referred to as "chlorine-containing plastic").

[0002]

2. Description of the Related Art Plastic wastes in general and industrial wastes (hereinafter referred to as "waste plastics") have the following problems in their treatment measures. (1) When heat treatment such as incineration is performed, chlorine-containing plastic is thermally decomposed to discharge toxic hydrogen chloride (HCl) gas. (2) In blowing into a blast furnace used as a reducing agent for an iron source, the permissible content of chlorine-containing plastic must be 1% or less. . (3) Landfill requires a large amount of land due to its large floor area ratio.

As methods for separating chlorine-containing plastics from mixed waste plastics, there are wet separation methods such as sink floats, liquid cyclones, wet vertical separators, and centrifugal separators, dry specific gravity shape separation, wind separation, near-infrared rays and X-rays. A dry separation method by absorption or the like is known.

[0004] However, in the wet separation method, there is no difference in specific gravity.
ET (polyethylene terephthalate) and PVC or PVD
Separation from C (chlorine-containing plastic) is not possible.
In addition, in order to float and separate PS (polystyrene), a heavy liquid having a specific gravity of about 1.2 must be used. Further, since a specific gravity liquid such as water is used for wet separation, there is a problem that wastewater treatment is indispensable, and the separated plastic needs to be dried.

[0005] On the other hand, in the case of dry separation, film-based plastics are difficult to align and have a problem of low throughput. In the case of dry-type specific gravity shape separation using a vibrating sieve and air flow, or wind separation, it is possible to separate plastics and paper or plastics and metals having a large specific gravity difference, but the same plastic, PE (polyethylene) ) And PP (polypropylene), PVC and PVD
It is impossible to separate materials having close specific gravities such as C (chlorine-containing plastic).

[0006]

As described above, the generation of HCl is a problem in heat treatment such as incineration and oiling of chlorine-containing plastics. However, in general waste plastics such as plastic containers and packaging, Incorporation of chlorine-containing plastics (PVC or PVDC) is inevitable. For this reason, in various kinds of reuse (recycling) of waste plastic, a separation technique for efficiently and inexpensively removing chlorine-containing plastic is required.

However, since many waste plastics are film-shaped plastics, the separation efficiency of chlorine-containing plastics is poor with the current simple separation technology.
Still, in order to obtain high separation efficiency, expensive equipment such as using a wet centrifugal specific gravity separation method is required,
There is a problem that processing cost becomes high.

Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a plastic separation method capable of separating chlorine-containing plastic contained in waste plastic with high accuracy, high efficiency and low cost. is there.

[0009]

According to the first aspect of the present invention,
Melt granulation of waste plastic using a predetermined melting temperature,
The present invention is characterized in that the obtained granules and non-granules not melt-granulated at the melting temperature are separated by dry separation means.

[0010] The invention according to claim 2 is that the waste plastic is melt-granulated using a melting temperature lower than the melting point of PVC and PVDC, and the obtained granules are combined with the PVC that has not been melt-granulated.
And non-particulate matter such as PVDC by a dry separation means.

The invention according to claim 3 is characterized in that the melting temperature is:
It is characterized in that the temperature is lower than the melting points of PVC and PVDC and higher than the melting point of PP.

The invention according to claim 4 is characterized in that the dry separation means is a dry specific gravity shape separation or a wind separation.

[0013] By melt granulation, plastic granules having a melting point lower than or equal to a set melting temperature and plastic non-granules having a melting point higher than the set temperature are obtained. If the melting temperature is lower than the melting point of PVC and PVDC and higher than the melting point of other non-chlorine-containing plastics, for example, higher than the melting point of PP, P
Only plastics having a melting point equal to or lower than the melting point of P can be granulated. Specifically, if the granulation temperature is set to less than 200 ° C. and 168 to 170 ° C. or more, PP and plastic granules having a melting point lower than that can be obtained. Incidentally, the melting point of the plastic, PE is 108-135 ℃,
PP is 168 to 170 ° C, PVC and PVDC are 200
２１０210 ° C.

PVC and PVDC having a higher melting point than PP
And the like do not melt, the shape does not change, and they remain in a lump or fragment form. In this way, PE and PP-based plastic (non-chlorine-containing plastic) granules and PVC and P
Non-particulates of VDC (chlorine-containing plastic) are prepared as a mixture.

[0015] Melt granulation is a process in which a specific gravity liquid is set to a desired melting temperature by a melt granulation device, for example, a specific gravity separation device using a specific gravity liquid, and the plastic is melted into droplets. This is a granulation method in which the molten plastic is cooled to obtain granules.

As a pretreatment for the melt granulation, the waste plastic is crushed to an appropriate size in advance or the components are broken up by some method before being introduced into the melt granulation apparatus. The size of the waste plastic after crushing by this crushing treatment is preferably about 20 to 200 mm. For example, in a crusher, in order to prevent physical entanglement, it is better that the crushing particle size is somewhat large, and the screen diameter is 20 to 200 mm. By performing a crushing process by a crusher having the screen diameter, it is possible to reduce the entrapment of PVC or PVDC into the granular material in the melt granulation and reduce the mixing ratio, and to reduce the chlorine content of the granular material. Can be. If less than 20 mm, PVC or PV
DC small-diameter material is caught in the granular material, and the chlorine concentration of the granular material (PE or PP system) increases.

Next, the mixture (granular material and non-granular material) prepared by the melt granulation device is introduced into a dry specific gravity shape separation device or a wind separation device, and separated into granular and non-granular materials.

The granular material obtained by separating from the chlorine-containing plastic in this manner is used as fuel (RD) used as a raw fuel for blast furnace injection for steelmaking, cement kiln and the like.
F) and the like.

[0019]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a process diagram according to an embodiment of the present invention, FIG. 2 is a perspective view of a melt granulation apparatus, and FIG. 3 is a perspective view of a dry-type specific gravity shape separation apparatus.

As shown in FIG. 1, a melt granulation device 2 is provided in a post-process of the crusher 1, and an air table type dry specific gravity shape separation device 3 is provided in a post-process of the melt granulation device 2. .

As shown in FIG. 2, the melt granulation apparatus 2 is a specific gravity separation apparatus using a specific gravity liquid. As the specific gravity liquid, for example, an aqueous urea solution is used. The waste plastic 11 introduced from the upper inlet of the main body 2a is mainly stirred by the stirring blades 4 rotated by the motor 5 in the specific gravity liquid (not shown) in the main body 2a, so that frictional heat is mainly generated. Then, the internal temperature (specific gravity liquid temperature) of the main body 2a increases. It is also possible to provide a heater or the like inside to control the temperature. When the internal temperature reaches a predetermined temperature, the plastic separated by specific gravity melts. At the same time, cooling water is sprayed into the main body 2a to solidify the molten plastic and granulate it. If the internal temperature is lower than the melting points of PVC and PVDC and higher than the melting point of PP, for example, if it is lower than 200 ° C. and higher than 168 to 170 ° C., only PE or PP (non-chlorine-containing plastic) can be melt-granulated. is there. The granules thus melt-granulated and the non-granules not melt-granulated are taken out of the shutter 6 as a mixture 11a.

As shown in FIG. 3, the dry specific gravity shape separation device 3 includes a vibrating sieve 7 that can vibrate substantially horizontally in a predetermined vibration direction 8 and a vibrating sieve 7 on the vibrating sieve 7 in a direction substantially parallel to the vibration direction. This is an air-table type separation device including a plurality of baffle plates (ruffles) 10 disposed therein and a rising air flow 9 which is jetted from a lower surface of a vibrating sieve 7 by jetting means (not shown). The mixture 11a taken out of the melt granulation device 2 is separated into a separation device 3
The vibrating sieve 7 is tilted (end slope) in the vibration direction 8 and is also tilted (side slope) in the horizontal direction orthogonal to the vibration direction 8. The mixture 11a on the vibrating sieve 7 is separated into the granular material 11b and the non-granular material 11c by a difference in specific gravity and a difference in shape by injecting the ascending air flow 9.

Note that the mixture 11a may be separated by using a wind separation device 12 shown in FIG. 4 instead of the device shown in FIG. As shown in FIG. 4, the mixture 11a is introduced into the main body 12a from the introduction port 13, and the mixture 11a is injected from the lower part of the tower 12a to the upper part by the blower 14 so that the mixture 11a is turned into the light-particulate matter 11b. And the non-granular material 11c on the heavy material side.

The process of separating waste plastic by the equipment shown in FIG. 1 is as follows.

The waste plastic 11 crushed in advance by the crusher 1 to remove foreign matter is introduced into a stirring-type melt-granulation apparatus 2 where it is granulated. Melting temperature (body 2a
By setting the specific gravity liquid temperature in the liquid to a temperature lower than the melting temperature of PVC and PVDC (chlorine-containing plastic) and higher than the melting temperature of PP, plastics such as PP and PE (non-chlorine-containing plastics) are melted and granulated. Is done. The particle size of the granular material as a reducing agent for the blast furnace iron source is preferably about 10 mm or less. On the other hand, PVC and P having a melting point higher than the melting temperature
VDC and the like have a shape (non-granular material) that remains crushed without being melted. These mixtures (granular and non-granular) 1
1 a is discharged from the outlet of the melt granulation apparatus 2.

Next, the mixture 11a discharged from the melt granulation apparatus 2 is introduced into the dry specific gravity shape separation apparatus 3, where it is separated into granular materials 11b and non-granular materials 11c.

The PE or PP non-chlorine-containing plastic granules 11b thus obtained can be reused as RDF or the like used for blowing into a blast furnace or the like.

[0029]

As described above, according to the present invention, the following useful effects can be obtained. Using a combination of melt granulation and dry specific gravity shape separation, etc., makes waste plastic a mixture of granular and non-granular materials by melt granulation, and separates the mixture into granular and non-granular materials by dry specific gravity shape separation etc. Thereby, the plastic in the waste plastic can be separated at low cost and with high accuracy. In the melt granulation, the chlorine-containing plastic can be separated from the waste plastic by using a melting temperature lower than the melting points of PVC and PVDC and higher than the melting point of PP, and it is possible to obtain granules mainly composed of PE or PP. it can. According to the present invention, chlorine-containing plastics (non-granules) are removed from waste plastics containing about 8% of chlorine-containing plastics (such as PVC and PVDC), and mainly plastics having a chlorine-containing plastic content of 1% or less. Granules can be obtained, and fuel (RD) used as a raw fuel to be injected into a blast furnace for steel making, cement kiln, etc.
F) and the like can be provided for reuse.

[Brief description of the drawings]

FIG. 1 is a process chart according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a melt granulation apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a dry specific gravity shape separating apparatus according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a wind power sorting device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crusher 2 Melting granulator 2a Main body 3 Dry specific gravity shape separation apparatus 4 Stirrer blade 5 Motor 6 Shutter 7 Vibrating sieve 8 Vibration direction 9 Air flow 10 Baffle plate (Rifle) 11 Waste plastic 11a Mixture 11b Granular material 11c Non-granular material 12 Wind separator 12a Tower 13 Input port 14 Blower 15 Blower

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tomohiro Miyazawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 4F201 AA14 AA15 AA50 AH81 BA04 BC01 BC12 BC25 BC37 BN15 BP08 BP09 4F301 AA16 AA17 AD02 BA01 BA11 BA12 BA21 BA29 BB10 BD29 BE15 BE18 BE31 BF03 BF08 BF09 BF12 BF16 BF21 BF31

Claims (4)

[Claims] 1. A waste plastic is melt-granulated using a predetermined melting temperature, and the obtained granules are separated from non-granules not melt-granulated at the melting temperature by dry separation means. And the method of separating plastic. 2. A method for subjecting waste plastic to melt granulation using a melting temperature lower than the melting points of PVC and PVDC, and dry separating the obtained granules from non-granules such as PVC and PVDC not melt-granulated. A method for separating plastics, comprising: 3. The method for separating plastics according to claim 2, wherein the melting temperature is lower than the melting points of PVC and PVDC and higher than the melting point of PP. 4. The method according to claim 1, wherein the dry separation means is dry specific gravity shape separation or wind separation.