JP2002219711A - Method for recycling electric wire-containing polyethylene resin pipe joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recycling an electric wire-containing polyethylene resin pipe joint, capable of ensuring the quality stability of a regenerated product regenerated from recovered matter and capable of enhancing the recovery of a polyethylene resin to almost 100%. SOLUTION: The method for recycling the electric wire-containing polyethylene resin pipe joint consists of a washing process B for washing the electric wire-containing polyethylene resin pipe joint to be recycled with water, a grinding process C for finely grinding the electric wire-containing polyethylene resin pipe joint washed in the washing process B, a specific gravity separation process D for charging the ground matter in a liquid and separating the ground matter on the basis of the specific gravity difference with the liquid and a granulation process G for granulating the polyethylene resin recovered in the specific gravity separation process D. A wind-force sorting process F for sorting the ground matter by utilizing wind force is provided between the grinding process C and the granulation process G.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A heating wire is used as one of the joints used for branching from a polyethylene resin pipe (hereinafter abbreviated as PE pipe) used as a conduit for gas or water or for joining PE pipes. There is a filled polyethylene resin pipe joint (hereinafter abbreviated as EF joint). The EF joint has a heating wire for heating embedded in the inner surface thereof, and is attached to a PE pipe to be joined. By supplying electric energy to the heating wire to generate heat, the inner surface of the EF joint and the outer surface of the PE tube are simultaneously formed. It is configured to melt and join. The present invention relates to a method for recycling an EF joint configured as described above.

[0002]

2. Description of the Related Art Since an EF joint is embedded not only with a polyethylene resin but also with a heating wire made of a metal or the like,
It was difficult to take out and recycle only the polyethylene resin, but in recent years, from the viewpoint of resource saving and environmental protection, research on its recovery method has been actively conducted. A method of recycling an EF joint that separates and collects a resin from a heating wire has been proposed (see JP-A-9-155866).

In such a recycling method, first, an EF joint to be recycled for disposal or the like is washed with water, and the washed EF joint is roughly pulverized and further finely pulverized. Next, the crushed piece is put into water having a specific gravity between the specific gravity of the heating wire and the crushed piece containing the heating wire and the specific gravity of 0.93 of the crushed piece made of polyethylene resin alone. Is ground in water, and only the crushed pieces made of polyethylene resin alone are floated and separated by specific gravity. Then, in this way, the crushed pieces containing the heating wire and the crushed pieces not containing the heating wire are separated, and the crushed piece containing the heating wire is discarded together with the heating wire, and only the separated and collected polyethylene resin is used. The resulting crushed pieces are appropriately subjected to a regeneration step and recycled into polyethylene resin.

[0004]

However, in the above-mentioned conventional method, the crushed material containing the heating wire, that is, the polyethylene resin mixed with the heating wire, is simply obtained by simply putting the crushed material into water and separating by specific gravity. Since it is discarded together with the heating wire, the recovery rate of polyethylene resin, that is, the recycling rate is as low as 95%, and there is a problem if foreign matter is mixed in the EF joint to be recycled, and there is still room for improvement. It was confirmed that was left. That is, in the specific gravity separation step, there is a problem that the specific gravity of the pulverized pieces containing the heating wire is larger than the specific gravity of the liquid used for the specific gravity separation, and sedimentation occurs with the heating wire.

[0005] In addition, when joining PE pipes using EF joints, for example, labels or tapes indicating the date of construction, the installer, the serial number of the EF joints, etc., are used for the EF joints.
May adhere to joints. Then, when such labels and tapes are made of non-polyethylene resin (for example, vinyl chloride resin), only the specific gravity separation by the above-mentioned conventional recycling method alone separates the polyethylene resin material with such foreign matter mixed in. There was a problem that it was easily collected. As described above, there is a possibility that foreign matters such as heating wires, labels, tapes, and the like may be mixed in the polyethylene resin material, and it is difficult to guarantee the stability of the quality of a recycled product reproduced from the polyethylene resin material. there were.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to ensure the stability of the quality of a recycled product to be recovered from a recovered product.
An object of the present invention is to provide a method of recycling a polyethylene resin pipe joint containing a heating wire, which can improve the recovery rate of polyethylene resin to almost 100%.

[0007]

According to a first aspect of the present invention, there is provided a water washing step of washing a polyethylene resin pipe joint containing a heating wire to be recycled, and a polyethylene resin pipe joint containing a heating wire washed in the water washing step. A pulverizing step of pulverizing the pulverized material into a liquid, separating the pulverized material by specific gravity according to a specific gravity difference from the liquid, and separating the pulverized material from the liquid by floating at an upper portion in the liquid; A specific gravity separation step of recovering a polyethylene resin heating product and a polyethylene resin heating wire mixture in which heating wires are mixed in the polyethylene resin, and heating the recovered polyethylene resin heating wire mixture to melt the polyethylene resin and solid The heating and heating step of separating the heating wire in the state and recovering the polyethylene resin material, and the specific gravity separation step and the heating separation step It is in place and a granulation step of granulating the polyethylene resin was recovered Ri.

[Action and Effect] In the specific gravity separation step,
Only the heating wire mainly composed of the heating wire is settled, and the polyethylene resin heating material mainly composed of the polyethylene resin and the polyethylene resin heating wire mixture in which the heating wire is mixed with the polyethylene resin are floated and separated. Then, the polyethylene resin heating wire mixture recovered in the specific gravity separation step, in the heating separation step, only the polyethylene resin component in a molten state, and separated from the solid heating wire by a filter or the like, and then to the polyethylene resin It will be subjected to a granulation step to regenerate. Therefore, since the heating wire is separated in the heating separation step in advance, the heating wire is prevented from being mixed into the recycled product,
It is possible to guarantee the stability of the quality of the recycled product that is recovered from the collected product. In addition, even if the heating wire is mixed in the polyethylene resin as described above, since the heating wire can be separated before being regenerated, in the specific gravity separation step,
By actively floating and separating not only the polyethylene resin material but also the polyethylene resin heating wire mixture, the recovery rate of the polyethylene resin can be improved, and the recycling efficiency can be further improved.

The feature of the invention according to claim 2 is shown in FIGS.
5, a water washing step of washing the polyethylene resin pipe joint containing the heating wire to be recycled, a pulverizing step of pulverizing the polyethylene resin pipe fitting containing the heating wire washed in the water washing step into finely pulverized products, Into a liquid, a specific gravity separation step of separating the ground material by specific gravity difference with the liquid, and a granulation step of granulating the polyethylene resin material recovered by the specific gravity separation step, Between the pulverizing step and the granulating step,
It is in performing a wind power sorting step of sorting the pulverized materials using wind power.

[Operation and Effect] In the period from pulverization of the EF joint to granulation of the recovered polyethylene resin, not only separation of specific gravity by pouring into a liquid but also pulverization using a wind force Since it is equipped with a wind separation process for sorting by dispersing etc., it is of course possible to separate and collect the polyethylene resin material from the heating wire object, even if labels and tapes are mixed in the polyethylene resin material. Even if it does, such labels and tapes can be sorted out. That is, while the shape of the polyethylene resin material formed by crushing the EF joint is lump, labels and tapes are crushed while maintaining the sheet-like shape. Therefore, the crushed material consisting of labels and tapes,
Even if it is mixed in the polyethylene resin material, it can be scattered more easily than the polyethylene resin material when sucked or blown by using wind power, so that it can be dispersed and selected from the polyethylene resin material.

[0011] Therefore, such foreign matters are less likely to be mixed into the polyethylene resin material finally separated and recovered, and the purity (concentration) of the polyethylene resin in the polyethylene resin material is improved, so that not only the polyethylene resin is recovered but also the polyethylene resin material is recovered. In addition, it is possible to guarantee the stability of the quality of the regenerated product that is regenerated from the collected material.

According to a third aspect of the present invention, in addition to the second aspect, as shown in FIG. 5, the wind separation step F is performed before the specific gravity separation step D. There.

[Operation and Effect] In the wind power sorting step, as described above, the crushed material is sorted by utilizing the wind power. Therefore, when the crushed material is subjected to the wind power sorting process, the crushed material needs to be dried to some extent. is there. However, since the wind separation step is performed prior to the specific gravity separation step using a liquid, the pulverized material is sufficiently dried, and can be subjected to the wind separation step without performing the drying step.

Therefore, the recycling operation can be simplified, and the EF joint can be easily and efficiently recycled.

According to a fourth aspect of the present invention, in addition to the second aspect of the present invention, the washed polyethylene resin pipe joint containing a heating wire is cooled before performing the pulverizing step. There is a cooling step to be performed.

[Functions and Effects] By cooling the EF joint in advance, even if labels, tapes, etc. (hereinafter simply referred to as “adhered matter”) adhere to the EF joint before being subjected to the pulverizing step, The adhering matter is different from the heating wire and the polyethylene resin constituting the EF joint, and thus is easily separated from the polyethylene resin in the pulverizing step. In other words, the physical properties (brittleness, etc.) associated with temperature changes due to each substance
Because the degree of change and the coefficient of thermal expansion (shrinkage) are different,
When the EF joint having the attached matter is subjected to the pulverizing step in a cooled state, the attached matter is more easily crushed than the polyethylene resin, and the attached matter is a substance such as a polyethylene resin material which originally constitutes the EF joint. And the separation efficiency of separating from the pulverized material consisting of

Therefore, since the foreign matter is pulverized in a state where the foreign matter is originally separated from the material constituting the EF joint, the recycled matter is more reliably selected from the polyethylene resin material and regenerated from the polyethylene resin material. Quality assurance can be more reliably assured.

According to a fifth aspect of the present invention, in addition to the second aspect, the specific gravity separation step is performed while stirring the liquid.

[Action and Effect] In the specific gravity separation step using a liquid, among the various pulverized materials generated in the pulverization step, a substance having a specific gravity larger than that of the liquid (mainly a heating wire mainly composed of a heating wire) is usually contained in the liquid. Settle and separate from polyethylene resin material. However, the shape of the pulverized material also varies widely, and various shapes such as granules, fibers, and wires are formed. And these are easily entangled with those with a large specific gravity,
In such an entangled state, it often sinks into the liquid.

Therefore, in the specific gravity separation step, by performing specific gravity separation while stirring the liquid, the entanglement of the pulverized materials is loosened and separated easily, and surely, the pulverized material having a specific gravity larger than the liquid is used. That is, only the heating wire tends to settle in the liquid. Therefore, in the specific gravity separation, the heating wire can be more reliably separated from the polyethylene resin material, and the recovery rate of the polyethylene resin material can be further improved, and the ratio of the other mixture mixed into the polyethylene resin material can be reduced. You can also do things.

As described above, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the accompanying drawings.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for recycling a polyethylene resin pipe joint (EF joint) containing a heating wire according to the present invention will be described below. As an example, an EF joint buried underground and used as a gas pipe is discarded. The recycling at the time of recycling will be described with reference to the drawings.

As shown in the process flow chart of FIG. 1, in the present embodiment, after a pre-treatment step A for pre-treating the EF joint, a water washing step B for washing the EF joint to be recycled is carried out. A pulverizing step C for pulverizing the EF joint into fine pulverized materials is performed. Then, pulverize the water (an example of liquid)
After performing a specific gravity separation step D for separating the polyethylene resin material and the heating wire material from the pulverized material, the foreign matter mixed in the polyethylene resin material is sorted out by wind separation using a wind force. And a granulation step G of granulating the collected polyethylene resin material.
Hereinafter, each step will be described in detail.

First, in the pretreatment step A, as shown in FIG. 2, a heating wire (for example, an iron wire) 2 is embedded from a polyethylene resin pipe (PE pipe) 1 for disposal taken out of the soil. The existing PE pipe portion, that is, the portion of the EF joint 3 is cut out with a saw or the like and taken out. In addition, such E
The F joint 3 has a label (manufactured by polyvinyl chloride resin (PVC)) indicating its serial number, and an EF joint.
When joining the E-pipe, tape (made of PVC) stating the name of the constructor and the construction date is still attached, and because it is buried underground, sand and soil are also attached. .

In the rinsing step B, in the next crushing step C, the removed EF joint is washed with water to remove sand and soil around the EF joint so that the crushing blade of the crusher does not wear much. .

Next, the washed EF joint is dried to remove water, and is supplied to the pulverizing step C. In the pulverizing step C, for example, the EF joint is finely pulverized using a shearing force by using a pulverizer 4 as shown in FIG.

FIG. 3 is a longitudinal sectional view of a main part of the crusher 4. The crusher 4 has a crushing portion 5 of a substantially cylindrical shape oriented horizontally, and is rotatable around a rotation shaft 6. A plurality of blades 8 are provided on a simple shank 7 to form a rotary blade 9, and a single fixed blade 11 is also provided on a peripheral wall 10 of the pulverizing unit 5. The shear force acting between the EF joint and the fixed blade 9 is used as a crushing force to finely crush the EF joint introduced into the crushing unit 5 from above and discharge the crushed material from the lower part of the crushing unit 5. It is configured in.

The lower portion 12 of the peripheral wall 10 is formed in a screen shape having a large number of apertures. It is pulverized repeatedly until it becomes a pulverized product of a size.
In the present embodiment, the size of the pulverized material to be generated is 10 mm
Grinding was performed until the size became about the same.

As a result, the types of the pulverized material include a heating wire mainly composed of a heating wire, a polyethylene resin mainly composed of a polyethylene resin, a substance mainly composed of a label and a tape (collectively referred to as foreign substances), and other materials described above. Various mixtures and various kinds of the above-mentioned were produced.

By the way, if the crushing step C is performed after the EF joint has been cooled beforehand, the difference in the degree of change in physical properties (brittleness, etc.) due to the temperature change and the heat Based on the difference in expansion (shrinkage) coefficient and the like, the foreign matter was more easily pulverized than the EF joint, and a pulverized substance in a state of the foreign matter alone separated almost 100% from the polyethylene resin was obtained. In addition, since the crushed material composed of foreign matter originally has a thin sheet shape, the crushing step C using the shear force as described above generates a similarly sheet-shaped material. Was.

Next, all the pulverized materials obtained in the pulverizing step C are dissolved in water (in this embodiment, the specific gravity of the polyethylene resin heating wire mixture in which the heating wire is mixed with the polyethylene resin among the pulverized materials is 1.0%). Water is used, the specific gravity separation step D is performed, and among the pulverized materials, a heating wire mainly consisting only of a heating wire is settled in water, and a polyethylene resin material and a polyethylene resin heating wire mixture are separated. Floated and separated. At this time, if the specific gravity separation work is performed while stirring the water, the danger of the heating wire being settled by being entangled with other pulverized materials is reduced, and the heating wire is more reliably separated from the other pulverized materials. It can be separated from the object, which is preferable. In this way, 97 to 98% of the heating wire contained in the EF joint before the treatment can be separated by sedimentation in water, and the remaining 2 to 3% is mixed in the polyethylene resin. The polyethylene resin heating wire mixture is recovered together with the polyethylene resin material.

Incidentally, some of the foreign substances made of PVC have a higher specific gravity than water, so that they can easily settle in water in this specific gravity separation step and can be separated together with a heating wire. However, since all of these foreign substances have a sheet-like shape as described above, they are susceptible to buoyancy and are entangled with polyethylene resin substances mainly composed of polyethylene resin among pulverized materials, so that they are immersed in water. There were some that could not be separated from the polyethylene resin that did not settle.

Therefore, in a wind sorting step F described later,
Only such foreign matter was separated from the polyethylene resin material by suction or blowing. However, as shown in FIG. 1, before moving to the wind separation step F, the polyethylene resin material and the foreign matter separated from the heating wire in the specific gravity separation step D are preliminarily separated so that only the foreign matter can be easily separated by suction or blowing. It is necessary to perform a drying step E for drying.

Next, the wind separation process F will be described. In this step, for example, only foreign matter can be sorted out from the polyethylene resin material by using a wind sorter 13 as shown in the schematic diagram of FIG.

The wind separator 13 is, as shown in FIG.
When the pulverized material is introduced into the processing unit 14 from the input port 15, the pulverized material is dispersed by the diffusion fan 16 provided at the lower part of the processing unit 14, and the material sowed by the dispersion is provided at the upper part. The air is sucked by the suction air blowing unit 17 and blown to the sorting port 18 to be discharged.
Is configured to be discharged from a discharge port 19 provided below the bottom.

As described above, in the case of a crushed product in which a polyethylene resin material and a foreign material are mixed, the foreign material has a sheet shape as described above, and has a relatively large surface area per unit mass as compared with the polyethylene resin material. With the above dispersion,
The foreign matter soared, was discharged from the sorting port 18 and was sorted, and only the polyethylene resin material was discharged from the discharging port 19. In this way, foreign matter was able to be separated from the polyethylene resin material by approximately 100%.

In the granulation step G, the polyethylene resin thus recovered was heated and melted to form a pellet, which was regenerated as a polyethylene resin. In this case, if a foreign substance made of PVC is mixed in the polyethylene resin material, dioxin may be generated. According to the present invention, as described above, the foreign material is separated from the polyethylene resin material by approximately 100%. Therefore, it is safe and the risk of environmental pollution can be reduced.

[0038] The polyethylene resin thus reclaimed is used for drainage pipes, agricultural watering pipes, explicit piles,
It can be recycled and used as conduit marking tape.

[Another Embodiment] Another embodiment will be described below. <1> The wind separation process F is not limited to the process performed after the specific gravity separation process D as described in the previous embodiment, and may be performed between the pulverization process C and the granulation process G. For example, FIG. May be performed before the specific gravity separation step D as shown in the step flow chart of FIG. In this case, the pulverized material is sufficiently dried because it is performed before the specific gravity separation step D using a liquid, and the pulverized material is subjected to the wind separation step F without performing the drying step E as in the previous embodiment. Therefore, the process can be simplified and the process is simple. Moreover, the polyethylene resin material recovered in the specific gravity separation step D is sufficient to be subjected to a drying step H for drying to a necessary degree when it is subjected to the granulation step G, and is naturally dried by sunlight or the like, or the drying step H itself is omitted. Since it can be incorporated into the granulation process G,
Energy required for heating and the like can be omitted, and resource saving can be achieved. The other points were the same as those of the previous embodiment. 97 to 98% of the heating wire could be separated from the polyethylene resin material, and the label and the tape could be separated at about 100%.

<2> Further, in the granulation step G, the recovered polyethylene resin heating wire mixture is heated to separate the polyethylene resin in a molten state from the heating wire in a solid state, thereby recovering the polyethylene resin. A process may be incorporated. For example, if the heating and melting polyethylene resin material is configured to pass through a filter on the way to separate the heating wire, the heating energy in the granulation process G can be efficiently used. Then, such a heat separation step can be performed. Then, the heating wire of 2 to 3% mixed in the polyethylene resin material is completely separated, the heating wire is not mixed into the recycle product, and the stability of the quality of the recycle product regenerated from the collected product can be guaranteed. In addition, the recovery rate of the polyethylene resin can be improved, almost 100% of the polyethylene resin can be regenerated, and the recycling efficiency can be further improved. The heating and separating step is not limited to the configuration performed at the same time as the granulating step, and may be performed separately from the granulating step.

<3> The recycling method according to the present invention is not limited to a socket-type EF joint in which a PE pipe is inserted into a PE pipe and joined to each other as shown in FIG. Needless to say, the present invention can be used for recycling an EF joint in which a heating wire for heating is embedded.

<4> The liquid used in the specific gravity separation step D is not limited to water, and a liquid having a specific gravity capable of separating the heating wire from the polyethylene resin and the polyethylene resin containing the heating wire is appropriately used. Good.

<5> As described above, according to the present invention,
About 100% of the heating wire can be collected and recycled.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram of an embodiment of a recycling method according to the present invention.

FIG. 3 is an explanatory view of an embodiment in a pulverizing step of the recycling method according to the present invention.

FIG. 4 is an explanatory view of an embodiment in a wind separation step of the recycling method according to the present invention.

FIG. 5 is a process flowchart of another embodiment of the recycling method according to the present invention.

[Explanation of symbols]

 B Washing process C Crushing process D Specific gravity separation process F Wind separation process G Granulation process

Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B07B 7/083 B07B 7/083 B09B 5/00 ZAB B29K 23:00 // B29K 23:00 B09B 5/00 ZABZ (72 ) Inventor Koji Toyoda Within Osaka Gas Co., Ltd. 4-1-2 Hirano-cho, Chuo-ku, Osaka-shi, Osaka (72) Inventor Nobuyuki Imamura 20-5 Katayama-cho, Kashiwara-shi, Osaka F-term in Osaka Jushi Kogyo Co., Ltd. (Reference) 4D004 AA21 BA07 CA04 CA08 CA10 CA14 CB13 4D021 FA12 GA02 GA12 HA01 4D071 AA41 AA81 CA03 DA15 4F301 AA13 AB02 BD01 BF03 BF09 BF12 BF27

Claims (5)

[Claims] 1. A water washing step of washing a polyethylene resin pipe joint containing a heating wire to be recycled, a pulverizing step of pulverizing the polyethylene resin pipe joint containing a heating wire washed in the water washing step into fine pulverized products, Injected into a liquid, the pulverized material is separated by specific gravity according to the specific gravity difference from the liquid, and separated by flotation on the upper part of the liquid, the heating wire is mixed with the polyethylene resin material and the polyethylene resin made of polyethylene resin. A specific gravity separation step of recovering the polyethylene resin heating wire mixture, heating the recovered polyethylene resin heating wire mixture, separating the molten polyethylene resin and the solid heating wire, and recovering the polyethylene resin material A heat separation step, and granulation for granulating the polyethylene resin material recovered in the specific gravity separation step and the heat separation step And a method for recycling a polyethylene resin pipe joint containing a heating wire. 2. A rinsing step of washing a polyethylene resin pipe joint containing a heating wire to be recycled, a crushing step of crushing the polyethylene resin pipe joint containing a heating wire washed in the rinsing step into finely crushed products, A specific gravity separation step of charging the pulverized material into a liquid and separating the pulverized product by a specific gravity difference from the liquid, and a granulation step of granulating a polyethylene resin material recovered by the specific gravity separation step, A method for recycling a polyethylene resin pipe joint containing a heating wire for heating, wherein a wind power selection step of selecting the pulverized material using a wind force is provided between a pulverization step and the granulation step. 3. The method for recycling a polyethylene resin pipe joint containing a heating wire according to claim 2, wherein the wind separation step is performed before the specific gravity separation step. 4. The recycling of a polyethylene resin pipe joint containing a heating wire according to claim 2 or 3, wherein a cooling step of pre-cooling the washed polyethylene resin pipe fitting containing a heating wire is performed before performing the pulverizing step. Method. 5. The method for recycling a polyethylene resin pipe joint containing a heating wire according to claim 2, wherein the specific gravity separation step is performed while stirring the liquid.