JPS5814958A - Method and apparatus for treating waste film for regenerated stock material - Google Patents

Abstract

PURPOSE:To promote separation of foreign matters from a waste film, by a method wherein ultrasonic wave is irradiated to the waste film segment in a washing tank opposedly from both side surfaces thereof as well as a recirculating water stream is forcedly formed and said film segment is subsequently washed by pressure shower completely. CONSTITUTION:A lump like substance of a waste synthetic resin film is crushed and cut to be supplied into a washing tank 4 from a hopper 5 and succeedingly conveyed by a net conveyor 13. To both side walls of the washing tank 4, ultrasonic vibrators 12 are provided so as to be mutually directed toward the inside of the tank 4 in a respectively opposed manner and vibration is impared to a liquid by low frequency vibration with about 30kHz to release sludge fixedly adhered to the waste film. In addition, a recirculating water stream is generated in the washing tank 4 by a stirrer 9 and an arranged pipe 19 connected to a pump P3 to further enhance washing effect. In the next stage, the waste film is discharged from the washing tank 4 by the conveyor 13 and washed on the rotary screen of the succeeding washing apparatus by a water spray means.

Description

[Detailed description of the invention] A method for separating and removing foreign substances such as impurities and contaminants adhering to or intervening in a film in order to recycle film waste made of plastic synthetic resin, and an apparatus for carrying out the method. It is related to.

In recent years, issues of energy conservation, particularly the conservation and efficient use of petroleum, its primary and secondary products as raw materials, have suddenly come to the fore. On the other hand, with the diversification of demand for horticultural crops and the spread of cultivated agriculture reflecting the increasing sophistication, the use of PVC film and agricultural film has rapidly increased, and as a result, the amount of waste Mt% has increased rapidly. be. Power·
We are forced to reconsider the disposal of plastic products from both the energy conservation and pollution issues mentioned above.
Recycling of waste has been cited as one of the effective measures to effectively solve the problem.

By the way, the waste plastic film bundles that are collected and accumulated by farmers usually contain earth, sand, and pebbles.

Contaminants such as wires, nails, cans, and glass, as well as impurities such as sludge and oil, are present or adhered to the material. Therefore, it is important to first separate and remove such foreign materials to obtain a clean material, which can be used for subsequent crushing and
Processes such as refining and regeneration? This is especially important for efficient and safe execution, and the emergence of a method to efficiently convert to highly purified plastic materials is of great significance.

Therefore, there has long been interest in the treatment of such waste plastic films, especially film waste made of polyvinyl chloride and polyethylene, which are widely used in agricultural and horticultural fields and tunnels, and attempts have been made to recycle them. .

In this conventional recycling method, the waste film is first bundled and compressed into chunks and sent to a crushing process, and after being crushed into a width of about 5oWrIn by a cutting machine, it is processed in the next foreign matter separation process. However, this foreign matter separation process is usually carried out by stirring and cleaning with air bubbles from below the water stream to remove pebbles.

Nails, sand, mud, etc. have been removed. These film pieces are further cut into pieces of 13 to 3 Otrrm W degrees in the next crushing process, and in a poly separation process, the mixed polyethylene films and the like are separated from the polyvinyl chloride. Only polyvinyl chloride is sent to the next dehydration step.

For dehydration, a centrifugal dehydrator is usually used, which consists of a rotating cone and a screw rotating inside the cone, and the film pieces are fed into the center of the cone and pressed against the wall of the cone under the action of centrifugal force. , water is removed in the downward direction of the larger diameter of the cone. The thus dehydrated film pieces are scraped up by a screw and dried in the next drying step to form the final product, so-called furan.

Furan is recycled, for example, as a raw material for molding vinyl chloride pipes.

However, in the conventional method described above, the separation action in the foreign matter separation step is mainly based on air agitation in the water, so although foreign matter with a high specific gravity such as pebbles, metal, sand, etc. It is difficult to remove light sludge, especially when using oil or the like.

In addition, the unprocessed film pieces have become slightly hardened due to aging, are compressed and bundled, and are further pressurized during stacking and storage, so that deformations such as wrinkles, folds, and folds are fixed. Since it does not fully expand even in water, it is even more difficult for foreign matter and sewage that are interposed or attached during the deformation to fall off. Insufficient cleanliness in this process not only reduces the quality of the final product, but also has various negative effects on subsequent processes. In other words, in the next crushing process, residual oil and fat will make the cutting blades difficult to cut, and residual sludge will damage the cutting blades.
This will lead to faster wear. In addition, if sludge remains until the next dewatering process, sand and mud will settle on the inner wall of the cone, and the flan will get caught between the screw and wall, causing the screw blades to become bent and reducing dewatering efficiency. Other inconveniences may occur.

In order to remove these sewage r, good results cannot be obtained even if sufficient washing with water is carried out in the crushing process or polyseparation process.

Therefore, the present inventor conducted intensive research to solve the problems of the conventional technology, and as a result, focused on the cleaning effect of ultrasonic waves, and by using this and heating at the same time, the cleaning effect is synergistic. It was discovered that the above-mentioned sewage and impurities could be completely removed within an extremely short period of time. The cleaning liquid R is maintained at such a level that the waste film inside becomes flexible and deformations such as wrinkles, folds, etc. formed and fixed on the film are extended and virtually eliminated, and the flow of the cleaning liquid at an appropriate temperature is maintained.・Use the waste film fragments γ
The waste film pieces are softened while being unrolled and migrated in the liquid, and the above deformation is substantially removed by stretching, and the waste film pieces are subjected to ultrasonic waves.
A method of separating and removing foreign substances on the film by irradiation was proposed.

However, although this method certainly had a superior cleaning effect compared to the conventional method, the waste film fragments that migrate in one direction flow out in the cleaning tank, causing liquid to flow out in the direction of transport. Due to the relationship between flow conditions and residence time in the tank, as well as insufficient agitation, the penetration of the waste film fragments that had formed into lumps into the depths was insufficient, and the results were not as effective as expected. It didn't work out.

Of course, it would be possible to solve this problem by increasing the length of the tank in order to increase the residence time in the cleaning tank, but this would require a large installation area and would not be practical.

In particular, when using the above-mentioned ultrasonic waves, the oscillators are arranged on both sides of the tank bottom, and the ultrasonic waves are emitted diagonally upward from the tank bottom, so wave vibrations are imparted. However, it was not possible to impart a sufficient unraveling effect to the waste film, and this is thought to be one of the reasons why the expected effect was halved.

In view of the above-mentioned circumstances, the present invention has been made to provide a method for processing waste film that further improves the method described above, exhibits further cleaning effects, and achieves a significant improvement in processing capacity. It is something to do.

Accordingly, the method and apparatus of the present invention, which are suitable for such purposes, apply ultrasonic waves to the waste film pieces in the cleaning solution from both sides in a direction perpendicular to the traveling direction in the above-mentioned method using ultrasonic waves. At the same time, a water stream 2 in the opposite direction is forcibly applied to the liquid flow in the transfer direction accompanying the transfer of the waste film pieces, giving the waste film pieces being transferred an opportunity to come into contact with the circulating water flow in the forward and backward directions of transfer. It is characterized by adding measures such as increasing the number of particles, washing with a pressure shower on a rotary screen, and promoting the separation of foreign substances.

Hereinafter, specific aspects of the present invention will be described in further detail according to the apparatus examples shown in the accompanying drawings.

Fig. 1 is an explanatory diagram showing an outline of the apparatus of the present invention, Fig. 2 is a schematic plan view of a cleaning tank which is the main part of the apparatus of the present invention, and Fig. 3 is a view perpendicular to the longitudinal direction of the washing tank in Fig. 2. 4 is a sectional view taken along the line X--X in FIG. 3.

In these figures, the present invention first transports the screened synthetic resin waste film lumps r to the coarse crusher (2) by the conveyor (1), After crushing and cutting, the coarsely crushed waste film pieces are sequentially supplied from the second conveying means (3) to the hopper (5) into the cleaning tank (4).In this case, the first conveyor (1) is not particularly necessary and may be supplied to the crusher (2) by manual operation, and the second conveying means (3) is not limited to the use of a conveyor as shown in the figure; The pumping mechanism used may be replaced.

As shown in FIGS. 1 to 3, the cleaning tank (4) is equipped with a guide wheel (6) at the bottom of the hopper (5), and the cleaning tank (4) is opened from the lower position of the guide wheel (6). (Net conveyor 03 with four extension adjusters Qlr at the end toward the 41 discharge section) is installed so that it can be driven by a motor CMO across each roll (R+), (RJ, and (R3)).
At the rear of the tank, a guide plate (71p fr) is attached, and a stirrer (9) driven by a motor (9M) is attached behind the guide plate (71p fr) to propel the liquid flow in the tank.

Behind this, there is a pump (P) on the cleaning agent tank side.
I) The tip of the cleaning agent supply pipe (101') connected through ' and the heating rod r injected into the tank (4), and the liquid injection pipe αυ connected to the boiler Uυ to adjust the liquid temperature r. ′
The tips of each are opened to prepare the cleaning liquid in the cleaning tank (4), and are further connected to a drain tank outlet provided at the lower part of the front end of the cleaning tank on the discharge side, which will be described later, via a pump (P4). The end (8) of the reflux pipe (2D) is open. On the other hand, the cleaning tank (4) has its both side walls facing each other so that ultrasonic waves are irradiated inwardly from each other. At least one pair of ultrasonic transducers (121, in the figure, two pairs are provided), and an ultrasonic frequency oscillator (12A) installed near the outside of the tank.
) and are connected to the oscillators (12A) and oscillated by driving the oscillator (12A) to vibrate the liquid in the premises using low frequency vibrations of around 30 kilohertz, thereby removing sludge, etc. stuck to the waste film in the tank. .

Here, the fact that the vibrators (121) are provided facing the side walls on both sides is one of the features of the present invention, and it can be seen that the effect is significantly improved when applying vibration noise from below. .

Although the arrangement of the vibrator is an important element in this cleaning tank (4), another feature is that a means for forcing the liquid in the tank to generate circulating water sound is provided.

That is, the agitator (9) at the rear of the cleaning tank is one of them, and a pump (PJ) is also connected to the drain tank a8 provided at the lower part of the cleaning tank (4), facing forward. A pipe a9 is formed which is connected to the cleaning tank (
4) The inside becomes a jet beak ■ that sprays water from the front to the rear, that is, toward the rear of the tank, and the water flows in the opposite direction to the transport force □ direction? is forming.

Therefore, in the washing tank (4), as shown in FIG.
Each water flow of the reverse water flow (D) that is ejected and generated from the jet beak (2) generates a circulating water flow as shown by the gradient, which exists around the ultrasonic vibrator α2 and is effective for ultrasonic cleaning of the waste film. It plays a role in further increasing effectiveness.

This cleaning tank (4) has the above-mentioned roles, but in addition, in the lower part of the cleaning tank (4), sludge molecules such as various dust, sand, iron pieces, etc. that settle through the ears 7 of the net conveyor 03) coagulate and settle. A flocculation tank Q51 is installed, which
A screw conveyor (Iη) is installed horizontally on the side, and the settled sludge molecules are collected from the discharge end of the conveyor αD into the sludge tank Q61 located below.The collected sludge is pumped as appropriate ( According to P2), piping is provided so that the sludge is collected together with the sludge carried out from other parts into a separately arranged sludge tank.

Washing tank (4J l'iAs described above, following the washing tank (4) and in front of it, there is a film-water mixing tank (22).
The film w washed in the washing tank (4) through 1r
A cleaning device is provided for better cleaning.

The cleaning device usually consists of a rotary screen, and a cylindrical wire mesh is installed, and along with this, cleaning water is applied to the film inside the cylinder. An example of water jetting means is also provided.

Although any water source can be used as the water injection means, in the present invention, it is connected to a separately arranged storage tank in order to enrich the continuous water system of the apparatus of the present invention.

In the figure, ) is the drainage tank in the cleaning equipment.

The cleaned waste film is then recycled by a series of take-out mechanisms connected to the cleaning device.

In the illustrated example, such a take-out mechanism is a conveyor (conveyor).

Each device consisting of a guide member, a drainage member, a pressure blower, and a cyclone is used, and is finally removed from the cyclone as a dried recycled film material. Here, each member uses a known device and can be easily designed by a person skilled in the art.

On the other hand, the apparatus of the present invention is accompanied by various water treatment apparatuses, and the part shown in the lower part of FIG. 1 is a power/force/filtration treatment apparatus.

Here, a storage tank Gυ, a first sedimentation tank C32, a second sedimentation tank (331, and a sludge tank (34) are provided, respectively, and five sedimentation tanks (321, a storage tank for supernatant liquid (3)) are provided. The water is returned and pumped for use in the cleaning and cleaning parts, and at the same time, the sediment is removed from the sedimentation tank (321, (
33+ to the concentration tank 09 and discharged using pump r or without using it.

In addition, the sludge collected in the sludge tank (341) is stored in a glue storage tank C361 equipped with an agitation device r as needed.

After receiving the adhesive from C37), the stirring device (34a)
While stirring, the mixture is gradually brought to a stalemate.

However, it goes without saying that these water treatment apparatuses are not necessarily limited to the above-mentioned apparatus configurations and may be modified in design as appropriate.

Next, in the series of apparatuses described above, to explain the case of cleaning the synthetic resin waste film r, first, hot water heated by the boiler 0υ is poured into the cleaning tank (4), and an appropriate amount is poured from the cleaning agent tank 00). Drop the cleaning agent and adjust the cleaning wave sound.

When injecting water at this time, heat it appropriately. □The temperature of the cleaning solution associated with sonic cleaning cannot be determined unconditionally and varies depending on whether the emphasis is on chemical cleaning or physical cleaning power. However, in the case of water, the maximum physical detergency is usually found at about 50°C. Therefore, the effect of ultrasonic vibration is maximum at about 50°C, but here, taking into account the relationship with the heat-resistant temperature of the vibrator of the device of the present invention,
It is best to perform two washings at about 5°C.

In other words, the temperature of this liquid varies depending on the type of thermoplastic synthetic resin/resin that forms the waste film agglomerates, the degree of aging, the fixed state of deformation X, etc. It is required that deformations such as wrinkles, creases, folds, etc. that are formed and fixed in the polyvinyl chloride are stretched to such an extent that they are virtually eliminated, and in the case of polyvinyl chloride, the
°C, and in the case of high-pressure polyethylene, it is 30 to 35
Approximately ℃ is appropriate. However, this is not necessarily fixed and can be determined in response to each condition.

〃・If the inside of the cleaning tank (4) is kept at an appropriate temperature, lumps of waste film will form. It is coarsely crushed by the crusher (2) and sequentially transferred to the hopper (5).
) The waste film r is sequentially fed into the cleaning tank by the guide wheel (6).

At this time, the inside of the tank is circulated through the guide wheel (6) and the drainage tank due to overflow, and the returned water and the agitator (9)
), an arrow-shaped water flow similar to that shown in Fig. 3 (B) and (() occurs, while a reverse water flow (D) in Fig. 3 occurs due to the jet of water from the front jet beak (20). do.

In this state, the ultrasonic frequency oscillator is activated from both sides, and when the ultrasonic wave of about 30 kHz is irradiated through the ultrasonic vibrator (12+K) to the waste film piece, the tank (4)
The waste film transferred on the net conveyor (13) is subjected to ultrasonic cleaning while being transferred to the above (B), (
0).

(D) Forced circulation of each water flow ensures sufficient retention in the tank, resulting in effective cleaning. receive.

Approximately 3
After being washed for 1 minute, it is carried out of the tank by the net conveyor α3 and sent to the next film-water mixing tank, whereupon the washing is completed by the pressure shower (of the rotary screen) in the washing process, and a series of steps are carried out. It is carried out from the cyclone (30) through a take-out mechanism. On the other hand, regarding wastewater treatment, the sludge that descends from the cleaning tank (4) passes through the ears r of the net conveyor 03) and is collected into the flocculation tank (15) below, and is transported as needed by the screw conveyor (lη). , After being carried out to the sludge tank (161), the wastewater receiving sludge tank C341
The water is sent to the water treatment facility.

Further, the waste water from the film-water mixing tank (rotary screen) is separately passed through a drainage tank (25), and is used as water for reprocessing after water treatment. In this case, the water in each drainage tank is the first one. After the water is treated by coagulation and sedimentation in the second sedimentation tanks (321, 331), it is passed through a filtration tank and circulated as reprocessed water to each device.

In particular, the chunks of film pieces cut in the above-mentioned coarse crushing process were irregular lumps of ribbon-like film pieces with a width of about 50 ttrm, and were fixed without being easily separated because they were charged with static electricity. In addition to complex deformation, various impurities and sewage are also stubbornly attached, making it extremely difficult to completely separate and remove these foreign substances using conventional methods. However, according to the method of the present invention, the lumpy waste film pieces are softened by the liquid temperature the moment they are put into the cleaning liquid, and are rapidly unraveled by the aforementioned forced circulation and water flow of the heated liquid. The film becomes more flexible as it migrates, and is irradiated with ultrasonic energy in a state where the deformation is extended and substantially eliminated. The sludge adhering to the surface is rapidly separated and fallen off in seconds, and is deposited on the bottom of the tank. In addition, fats and oils are also removed by the degreasing action of ultrasonic energy, and can be completely removed by using a detergent in combination.

As is clear from the above explanation, according to the method of the present invention, by heating the cleaning liquid to a higher temperature, not only the ultrasonic cleaning effect is significantly improved, but also the waste film fragments made of thermoplastic synthetic resin are reduced to lumps. Unraveling the object 7. Hold the film piece r.
The synergistic effect of stretching the film to make it easier to clean is fully demonstrated, and all sewage and impurities can be completely removed in a short period of time, and bacteria attached to the film can also be removed by ultrasonic waves. It has the added benefit of being able to sterilize.

Therefore, the film pieces sent out from the foreign matter separation process using the method of the present invention are cleaned in a very clean state, so they can be used in the subsequent crushing process and dehydration process without additional washing with water. It is possible to increase processing capacity without damaging or abrading mechanical parts such as crusher blades and dehydrator screws, and to maintain the quality of the flannel product at a high level.

Next, an embodiment of the present invention will be described.

EXAMPLE Foreign matter separation from a waste polyvinyl chloride film was carried out using an apparatus as shown in FIGS. 1 to 4 having a washing tank r having a width n, a length of 4 m, and a depth of 1 m. Fill the washing tank with warm water and add commercially available alkaline detergent 1. After adding '51'77, while operating the stirrer R, the cleaning liquid was circulated by spraying V jets. When the liquid temperature was 45''C-, 20kg of coarsely crushed PVC waste film pieces were put into the tank, and irradiated with 30KH2 ultrasonic waves for 3 minutes of cleaning.The waste film before being put into the cleaning tank. The amount of lumps is 4 to the weight of the film.
It contained 7.1% of foreign matter such as earth and sand, but the amount of foreign matter remaining after cleaning decreased to 0.4%, and the foreign matter removal rate was 99.2%.
Met.

Next, as a result of various studies, we decided to measure the spectral transmittance r of the film as a means of numerically indicating the cleaning effect of this device.

The result was that the light transmittance of the film was 0°5μ from the visible region.
There was no significant difference in the infrared region up to 100 nm, and since it was necessary to measure at a wavelength at which the transmittance of the film was stable, measurements were carried out at a wavelength of 550 mμ.

This transmittance varies greatly depending on the condition of the film.
For example, if the film is wet or has scratches or bends on the surface, it will cause a decrease in light transmittance. However, when we measured the transmittance r of the above-mentioned PVC waste film and converted it to the cleaning rate, we found that the raw material film The transmittance of
It was confirmed that the cleaning rate after approximately 60 seconds of ultrasonic cleaning according to the present invention was 95 to 96%, which was approximately 45% when converted into a cleaning rate.

Incidentally, the cleaning rate is the transmittance of the new film '11o.

It is calculated from the transmittance as %.

For comparison, cleaning was carried out under the same conditions as above, except that the liquid was agitated and aerated through three air supply pipes installed at the bottom of the tank using a conventional aeration flowing water moving type foreign matter separation tank. The foreign matter removal rate was 96.2%.
The cleaning rate calculated in terms of transmittance was about 70 to 13%.

In addition, when the method of increasing residence time using forced circulation water flow of the present invention was carried out in the same way as ultrasonic cleaning, the cleaning efficiency in terms of transmittance was about 83 to 85%, which was a remarkable difference.
had.

As described above, according to the present invention, although it is a water-type cleaning tank, it is possible to achieve a processing capacity of about 3 times or more compared to a conventional plant by ultrasonic cleaning. It suffices to use approximately half the surface area, and since cleaning is mainly performed using ultrasonic energy, the amount of power used is significantly reduced compared to conventional methods, resulting in energy savings. can be achieved.

In particular, with regard to the washed film, due to the forced circulation of water in the washing tank and the subsequent circumstances, a product of high purity with less foreign substances than the conventional method can be obtained. There are also great expectations for preventing pollution caused by landfilling and incineration.

Furthermore, in the case of the present invention, the coagulation and sedimentation method can be used for wastewater treatment, and since all of the wastewater is recycled and recycled, the amount of water discharged into public water bodies is small and has almost no impact.

By smelling, the quality of synthetic resin waste film can be improved and maintained.The retention time in the water tank is increased due to the circulation movement of the water flow.In combination with the subsequent situation, ultrasonic cleaning acts more reliably on the waste film. , not limited to PVC waste film,
The effectiveness of this technology as an improvement in the effective utilization of all kinds of thermoplastic synthetic resin waste films is extremely large, and there are great expectations for its practical application in the future.

[Brief explanation of the drawing]

Is Fig. 1 the method of the present invention? An overview of the equipment used. Figure 2 is a schematic plan view of the cleaning tank of the same equipment, Figure 3 is an explanatory diagram of
The figure is a side sectional view of the cleaning tank in FIG. 2, and FIG. 4 is a sectional view taken along the line X--X in FIG. 3. (2)...Crushing machine, (3)...Transportation means. (4)...Cleaning tank, (6)...Guide car. (91... Stirrer, (12+... Ultrasonic vibrator. 03)... Net conveyor, (19... Sludge coagulation tank. (17)... Screw feeder, (20+...
・Backflow lit injection beak (231...Rotary screen. Example...Water injection means.

Claims (1)

[Scope of Claims] l After crushing waste film chunks made of thermoplastic synthetic resin, immersing them in a cleaning solution, irradiating the waste film pieces with ultrasonic waves in the solution, and utilizing the flow of the cleaning solution. The crushed waste film lumps are unraveled and migrated in the liquid, softened, and deformed wrinkles, folds, etc. formed and fixed on the waste film are substantially removed by stretching, and foreign substances on the film are separated. In the method of removing the waste film, the waste film piece is irradiated with ultrasonic waves from both sides facing each other, and the washing liquid is forcibly formed with a circulating water flow in the front and back direction with respect to the waste film transport direction. The method for treating waste film for recycled raw materials is characterized in that it is then further thoroughly washed with a pressure shower. 2. The method for treating waste film for recycled raw materials according to claim 1, wherein the cleaning liquid has a liquid temperature of 40 to 45°C. 3. Claims 1 or 2 in which the waste film made of thermoplastic synthetic resin is a polyvinyl chloride film.
A method for processing waste film for recycled raw materials as described in . t means for crushing the synthetic resin waste film lumps to be treated; means for conveying and supplying the waste film coarsely crushed by the means to a cleaning tank; a cleaning means for cleaning the waste film in a liquid; The cleaning means further includes means for cleaning the washed waste film, and the cleaning means includes a cleaning tank 4 containing a cleaning liquid therein, and the cleaning tank has ultrasonic vibrations opposite to each other on both side walls thereof. Is there a liquid flow propelling agitator on the cleaning tank inlet side? On the other hand, the outlet side is equipped with means for injecting liquid r against the direction of waste film transport, and inside the cleaning tank there is provided a net conveyor extending from the lower part of the supply means to the detection port, and a separate conveyor is provided at the lower part of the net conveyor. A means of discharging dirty purple? A method for processing waste film for recycled raw materials.