JPH07178351A - Electrostatic sorting device for rubber and plastic waste - Google Patents

Abstract

PURPOSE:To provide an inexpensive sorting device which is capable of accurately sorting the rubber and plastic waste generated at the time of production of electric wires and cables by kinds of materials and does not require a waste water treatment, etc. CONSTITUTION:An agitating machine 11 which is driven by a motor 10 and electrifies an insulating material by friction at the time of agitation is connected to a hopper 3 for supplying the crushed rubber and plastic waste 2. The end of the agitating machine 11 is connected through a small-diameter falling hole 12 to a dropping pipe 13. Parallel flat plate electrodes 14 applied with 21 DC high voltage are arranged to face each other in the intermediate part of the dropping pipe 13 so that the electrified waste particles receive the electrostatic force by the DC electric field generated between the parallel flat plate electrodes 14 during the course of dropping and are attracted and divided toward the electrode side of the polarity on the opposite side.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention eliminates rubber / plastic waste generated during or after the production of electric wires / cables.
The present invention relates to an apparatus for selecting a conductive material and an insulating material or a type of insulating material by using static electricity.

[0002]

2. Description of the Related Art In the field of electric wires and cables in recent years, a large amount of electric wire and cable waste generated during manufacturing or after use is crushed, and copper is separated and recovered by a specific gravity sorting method using vibration and wind force (nugget. System), the rest of the recovered copper,
It is mainly landfilled as industrial waste. That is,
A small amount of copper remains in the residual copper recovered from electric wire / cable waste, and conductive polyethylene (P
E) may be mixed, but polyvinyl chloride (PV
C), polyethylene (PE) and other coating materials occupy most of them, and since there is no effective method for selecting them, they are currently disposed of as landfill as industrial waste.

By the way, in selecting rubber / plastic crushed materials other than electric wire / cable covering materials, dry specific gravity sorting methods such as wind power sorting or fluidized bed sorting, or wet type sorting such as floating / sink sorting or centrifugal sorting. Although specific gravity sorting methods are used, if the dry specific gravity sorting method is used to sort out the rubber / plastic waste of electric wires / cables described above, it is sorted by specific gravity, weight, and size. Although it is effective for sorting, etc., there is a problem that it is difficult to improve the sorting accuracy between crushed rubber / plastics having the same shape. Further, among the wet specific gravity sorting methods, the floating sedimentation sorting method is effective when sorting polyolefin-based plastics and other plastics, but there is a problem that the wastewater used for sorting is required to be treated. Further, the hydrocyclone centrifugal separation method has a wide range of application depending on specifications and operating conditions, but has a problem that the apparatus is expensive and requires wastewater treatment.

[0004]

Thus, from the viewpoint of resource reuse and environmental protection, it is required to select and recover not only electric wire / cable covering material waste but also general rubber / plastic waste. However, conventional techniques for selecting crushed rubber / plastic crushed materials have not been sufficient in terms of environmental impact and sorting accuracy by type.

The present invention has been made to solve these problems, and it is possible to accurately sort wastes mainly of rubber and plastic produced during or after the production of electric wires / cables by the type of material. It is an object of the present invention to provide an inexpensive device that can be processed and does not require wastewater treatment.

[0006]

An electrostatic separation apparatus for rubber / plastic waste according to the present invention comprises means for supplying rubber / plastic waste, and continuous conveying means connected to the supply port of the supplying means. A charging means for charging the rubber / plastic waste with an electric charge, a means for dropping the rubber / plastic waste carried by the carrying means and charged by the charging means, and a rubber / plastic falling by the dropping means A means for applying an electrostatic force to the waste to change the falling direction according to the presence or absence of electrification and the type of electric charge, and a plurality of recovery containers juxtaposed below the electrostatic force applying means. It is characterized by

The rubber / plastic wastes to be sorted according to the present invention include various olefin polymers such as PE, polypropylene and ethylene-propylene copolymer, and a mixture of insulating materials such as PVC, butyl rubber and styrene-butadiene rubber. In addition, conductive PE
A conductive rubber or plastic such as the above may be mixed. In the present invention, such rubber / plastic waste is crushed in advance into a coarse grain or powder by a known crushing means.

Further, in the present invention, as a means for charging the rubber / plastic waste crushed as described above with an electric charge, for example, a high voltage is applied between the needle electrode and the other electrode, and the needle electrode A method of charging by inducing a corona discharge from the tip of the, a method of applying a high voltage and using dielectric polarization, or a method of stirring a mixture of insulating materials and charging by friction is used. .

[0009]

According to the electrostatic separation apparatus for rubber / plastic waste of the present invention, the rubber / plastic waste, which has been crushed into coarse particles or powder by a known means, is supplied to the continuous conveying means and is conveyed. In the process or after being conveyed, the charging means gives a charge having a different sign depending on the type of material, for example, and then falls. Then, in the dropping process, different electrostatic forces are applied to these charged rubber / plastic wastes depending on the presence or absence of electrification and the type of electric charge, and the dropping direction is changed. As a result, the charged electric charge reaches the corresponding recovery container through a different drop path and is recovered. Therefore, rubber
The plastic waste can be efficiently sorted according to the type of the constituent material, and the sorting accuracy can be improved.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing an embodiment of an electrostatic sorting apparatus for rubber / plastic waste according to the present invention.

In FIG. 1, reference numeral 1 denotes a vibrating and conveying device for vibrating a contained substance to convey it in a horizontal direction by a constant amount, and at the inlet end thereof, electric wire / cable waste is crushed to separate copper. Remaining collected rubber / plastic waste 2
Is connected to a hopper 3 for supplying. In addition, at the outlet side end of the vibration transfer device 1, the rubber
A device is arranged for charging the plastic waste 2 by corona discharge. That is, in this charging device, the rotating electrode 4 is arranged so that the cylindrical electrode surface is located on the extension line of the conveying path of the vibrating conveying device 1, and the tip portion of the rotating electrode 4 is slightly above the rotating electrode 4. The rotating electrode 4 is composed of a needle electrode 5 arranged so as to face the electrode surface, and the rotating electrode 4 is grounded. Then, a high DC voltage is applied between the needle-shaped electrode 5 and the rotating electrode 4 to generate corona discharge at the tip of the needle-shaped electrode 5. Further, a plurality of collection containers 6 are arranged side by side below the electrode surface (tangential direction) of the rotating electrode 4 of such a charging device, and further below the rotating electrode 4, the collecting container 6 is attracted to the electrode surface. A brush 7 for scraping off the rubber / plastic waste transferred as it is is arranged in contact therewith. In the figure, reference numeral 8 indicates an insulating cover for enclosing a charging device and the like for ensuring safety,
Reference numeral 9 indicates an operation panel for electrically operating the apparatus. In the electrostatic sorting device configured as described above, the rubber / plastic waste 2 in the form of particles supplied from the hopper 3 is horizontally transported at a constant speed by the vibration transport device 1, and then the rotating electrode is used. After passing through the electrode surface of No. 4, it falls downward. However, since corona discharge is occurring at the tip of the needle-like electrode 5 arranged opposite to the rotating electrode 4, gas ions having the same polarity as the polarity on the high voltage side generated as a result of the discharge have been conveyed. -It adheres to the plastic waste 2, and as a result, the rubber-plastic waste 2 is charged to the same polarity. When the charged rubber / plastic waste 2 reaches the electrode surface of the rotary electrode 4, the conductive particles and the insulating particles have different falling behaviors. That is, in the conductive particles, the charged electric charge travels through the grounded rotary electrode 4 and immediately escapes, so that the conductive particles quickly slide down on the electrode surface of the rotary electrode 4, and the recovery container 6a disposed at the foremost position. Fall inside. On the other hand, in the insulating particles, the electric charge does not escape and remains charged, and the electrostatic force between the electric charge and the rotating electrode 4 causes the particles to be attracted to the electrode surface of the rotating electrode 4. Then, as the rotating electrode 4 rotates, it is transferred in the circumferential direction, falls at a point where gravity becomes larger than the electrostatic force, and falls in the collecting container 6b arranged behind the conductive particle collecting container 6a. Fall inside. Furthermore, when the two particles of rubber / plastic waste are insulating and sufficiently small, the electrostatic force is larger than the gravity even at the lower part of the rotating electrode 4, so that the particles should fall while being attracted to the rotating electrode 4. However, this is finally scraped off by the brush 7 and the recovery container 6
It falls into c. In this way, the conductive particles and the insulating particles in the rubber / plastic waste 2 are efficiently and accurately sorted and collected. The collection container 6
It is preferable to further arrange the recovery small container 6b between a and 6c, but in that case, both the conductive particles and the insulating particles are mixed and fall into the recovery small container 6b. By returning to the hopper 3 and sorting again,
Further, the sorting accuracy can be improved.

Next, another embodiment of the present invention will be described. FIG. 2 shows an example of an apparatus for sorting rubber / plastic waste of electric wires / cables according to the type of insulating material such as PVC or PE. In this apparatus, rubber / plastic waste 2 such as crushed particles is used. The stirrer 11 driven by the motor 10 is connected to the supply port of the hopper 3 for supplying. The end of the stirrer 11 on the outlet side is connected to a drop tube 13 through a drop hole 12 having a small diameter, and a parallel plate electrode 14 is disposed in the middle of the drop tube 13 so as to face each other across the drop path. There is. A high DC voltage is applied between the flat plate electrodes 14 so that a uniform DC electric field is generated between the electrodes. Further drop tube 1
At the bottom of 3, a plurality of recovery containers 6 are juxtaposed side by side.

In the apparatus of the embodiment thus configured, the rubber / plastic waste 2 in the form of particles, which is supplied to the stirrer 11 through the hopper 3, is vigorously stirred in the stirrer 11 to be mutually agitated. After being charged with an electric charge having a different sign depending on the type of the insulating material due to friction, it drops through the small diameter drop hole 12 and at a constant speed in the drop tube 13. Then, the two particles of the rubber / plastic waste thus charged are subjected to the electrostatic force by the DC electric field generated between the parallel plate electrodes 14 during the fall, and the positively charged particles are the particles negatively charged to the negative electrode side. Are attracted to the positive electrode side and fall into the recovery container 6 arranged at a position close to each electrode. Therefore, for example, when selecting the rubber / plastic waste 2 made of a mixture of PVC and PE, PVC particles negatively charged by friction are collected in the collection container 6d near the positive electrode and collected in the collection container 6e near the negative electrode. In this case, positively charged PE particles are collected respectively, and highly accurate sorting is performed according to the type of insulating material.

Next, a concrete experimental example in which rubber / plastic waste is sorted by using the apparatus of the embodiment will be shown.

First, as a sample of rubber / plastic waste, 50:50 of conductive PE particles and insulating PE particles was used.
(Weight ratio) mixture (Experimental Example 1), conductive PE particles and PVC particles in a 50:50 mixture (Experimental Example 2), and conductive PE particles, PE particles and PVC particles each 1/3 A mixture of each weight (Experimental Example 3) was prepared, and these samples were supplied to the hopper of the apparatus shown in FIG. Then, a high DC voltage of Kv is applied to the needle-shaped electrode 5 to generate corona discharge at the tip, and the high-voltage electrode side receiving tray (collection container 6a), the intermediate receiving tray (recovery container 6b), and the ground electrode side receiving tray ( The proportion of each particle collected in each container of the collection container 6c) was measured.

The measurement results are shown in Table 1.

[0017]

[Table 1] From Table 1, it was found that the conductive particles and the insulating particles contained in the sample were sorted with high accuracy.

Further, using the apparatus shown in FIG. 3 which is a simplified version of the apparatus shown in FIG.
The mixture mixed at a weight ratio of 50 was selected (Experimental Example 4). That is, this mixture is put in the hopper 3, stirred in the hopper 3 and charged by mutual friction, and then passed through a small-diameter PVC pipe 15 having a bent portion to relax the falling speed, and at a slow speed. I dropped it. Then P
Two recovery containers placed below the VC pipe 15 and dropped between the parallel plate electrodes 14 to which a high DC voltage of 50 Kv is applied, and placed near the positive electrode (ground electrode) and the negative electrode (high voltage electrode). It collect | recovered to 6d and 6e, respectively. Then, the proportions of PE particles and PVC particles collected in each container were measured.

The measurement results are shown in Table 2.

[0020]

[Table 2] From Table 2, it was found that PE particles and PVC particles contained in the sample were sorted with high accuracy.

[0021]

As described above, according to the device of the present invention, rubber / plastic waste produced during the production of electric wires / cables can be efficiently and accurately classified according to the presence or absence of conductivity and the type of material. Since they are selected, the resources can be collected and reused. In addition, it does not require wastewater treatment and has little impact on the surrounding environment.

[Brief description of drawings]

FIG. 1 is a configuration diagram schematically showing an embodiment of an electrostatic sorting apparatus for rubber / plastic waste according to the present invention.

FIG. 2 is a configuration diagram schematically showing another embodiment of the electrostatic sorting device according to the present invention.

FIG. 3 is a configuration diagram schematically showing an electrostatic sorting device used in a specific experimental example of the present invention.

[Explanation of symbols]

1 ………… Vibration transfer device 2 ………… Rubber / plastic waste 3 ………… Hopper 4 ………… Rotating electrode 5 ………… Needle electrode 6 ………… Collection container 7 ………… Brush 8 ………… Insulation Cover 9 ………… Control panel 10 ………… Motor 11 ………… Stirrer 12 ………… Small diameter drop hole 1 13 ………… Drop tube 14 ………… Parallel plate electrode 15 ……… Small diameter PVC pipe

Claims (2)

[Claims] 1. A means for supplying a rubber / plastic waste, a continuous transfer means connected to a supply port of the supply means, a charging means for charging the rubber / plastic waste with an electric charge, and the transfer means. A means for dropping the rubber / plastic waste that is conveyed and charged by the charging means and a horizontal direction electrostatic force is applied to the rubber / plastic waste that is falling by the dropping means to charge the waste. Electrostatic sorting of rubber / plastic waste, characterized by comprising a means for changing the falling direction according to the presence or absence and the type of electric charge, and a plurality of collection containers juxtaposed below the electrostatic force applying means. apparatus. 2. A crushed and granular plastic waste is charged by corona discharge or electrostatic polarization, and is separated into conductive particles (metal, conductive polyethylene, etc.) and insulating particles, and subsequently, triboelectric charging. An electrostatic sorting device that sorts insulating particles by type of insulating material.