CN201061774Y - Plastic electrostatic go-on-go system - Google Patents

Abstract

An electrostatic sorting system for plastics consists of a rotating drum (1) made of metal material for containing particles. The drum has an inlet (11) for charging the material and an outlet (13) for discharging the material. The drum also contains means (7) allowing it to be rotated about an axis of rotation oriented such that the particles collide with each other or with the walls of the container during operation of the device, thereby triboelectrically charging them. The outer surface of the drum is provided with a particulate filter screen member (10) for filtering particulates from the drum. An electrostatic separation tower (20) having conical walls flanked by at least one pair of electrodes (24) for receiving discharged material flowing from the drum. The separation tower separates the particles falling from the drum into the tower (20) in the electric field formed by the electrodes (24).

Description

Plastic electrostatic sorting system

technical field

The utility model relates to the improvement of electrostatic separation of materials, especially mixed plastic waste materials. This separation enables inter alia the purpose of recycling and reusing the material. The utility model also relates to the method for separating other electrical insulating materials from each other, or separating other electrical insulating materials from conductive materials such as metals.

Background technique

Waste plastics are mainly generated from garbage or production waste from the manufacturing of plastic consumer goods, and it is necessary to separate the different types of plastics. Electrostatic separation, which separates plastics according to their electrostatic charge, is a well-known method of achieving this desired separation. Waste plastics are first chopped or chopped into relatively small particles, which are then electrostatically separated after being charged by suitable means.

When electrically insulating materials with different work functions (including most plastics) come into contact with each other, a static charge builds up on the materials. Assuming that the work function of material A is smaller than that of material B, direct physical contact between material A and material B will result in the transfer of electrons from A to B. The material becomes electrified by friction. Material A will be positively charged, and material B will be negatively charged due to gaining electrons.

Triboelectrification occurs only when the work functions of the two materials in contact differ. In rare cases, because of the crystal structure of the material, the work function of one point on a material crystal may be slightly different from another point on the same crystal surface. In this case, even the same material may have a slight triboelectric charge.

Different situations where plastic materials are brought into contact in the above manner to acquire charges can serve as a basis for separating material A and material B mixed together by an electric field. The purpose of the utility model is to increase the range of the triboelectric charge that can be accumulated in the material, and then improve the separation efficiency.

Triboelectric generation can only be used between electrically insulating materials or between metals and electrically insulating materials. Triboelectricity cannot be used to separate conductive materials such as two metals. For example, if copper and nickel are brought into contact, charge transfer occurs because the work function of nickel is much greater than that of copper. However, if one tries to separate the particles, the charge quickly flows back to where it was generated, with the result that both metal particles become neutral after separation.

US Patent No. 5,289,922 to Inculet et al. discloses electrostatic separation of mixed plastic waste. Inculet et al. disclose a device for triboelectrically charging particles of insulating material. The device includes a container containing particles of a material having a work function different from that of at least some of the particles in the container. The container is rotatable and the device includes a means for rotating the container about the axis of rotation. The axis of rotation is oriented such that the particles collide with each other or with the walls of the container during operation of the device, thereby triboelectrically charging them.

The mixture of plastic materials to be separated is fed in at the inlet of the container and out of the pipe at its outlet. The apparatus also includes a means for moving the material passing through the container stepwise from the inlet to the outlet; the arrangement of the apparatus being such that material at any point in its journey between the inlet and outlet can be separated from material elsewhere.

The particle travels through the container in such a way that the particles do not mix universally, ie they do not mix with particles at different charge levels, but only with particles at the same charge level. In this way, the charge of the particles can gradually increase when passing through the container, and will not be consumed.

The container is preferably tubular, open at both ends, and the triboelectrically charged particles enter one end of the tube and exit the other end. The tube is set to be rotatable, its rotation axis is inclined at a small angle relative to the horizontal plane, and the inlet is on the top and the outlet is on the bottom. The rotational speed of the tube and the aforementioned inclination angle are preferably adjustable.

The tube may comprise at least one rib of the same material as that extending radially inwardly from the inner surface of the tube wall. The ribs are positioned along the axial length of the tube so that when the tube is rotated, the ribs flip the particle mixture inside the tube.

The separation device also includes a channel placed at the end of the tube, the channel bottom has at least one opening (such as an elongated slot, preferably tapered, or many small holes) so that the particles fall through it like a particle curtain, the channel High-voltage electrodes are set on both sides and extend vertically downward to separate particles.

The purpose of this structure is to provide a method of frictional electricity generation which is efficient in operation and reduces capital cost and energy consumption compared to conventional fluidized bed equipment. Although the device disclosed by Inculet et al. has achieved the above objects, there are still some disadvantages in the device, and the present invention attempts to overcome these disadvantages.

Because in the process of electrostatic separation, the separation is based on the charge-to-mass ratio, and the charge-to-mass ratio will increase linearly with the decrease of particle size, so the uniform particle size is a very important factor in determining the separation purity and separation volume of mixed plastics. As deposits build up, highly charged particles accumulate on the electrodes and reduce the electric field strength, thereby reducing separation efficiency.

At one stage of the separation process, as disclosed by Inculet et al., there is a channel at the end of the tube with a plurality of openings or a tapered slot at the bottom through which the particles fall like a curtain of particles. High-voltage electrodes are arranged vertically on both sides of the channel in a tower-like form and extend down along it to separate particles. A disadvantage of this device is that there is no immediate or continuous feedback to the operator of the amount of separated material dispensed.

In order to obtain a better separation rate and a higher particle throughput rate, a continuous particle flow aligned parallel to the electrode is required from the above stage, because the separation zone only operates in the direction perpendicular to the electrode. The initial velocity of particles entering the tower should also be consistent and as small as possible. However, none of the aforementioned techniques is sufficient to achieve these two points.

Contents of the invention

The purpose of the utility model is to improve the plastic electrostatic sorting system for electrostatic separation of mixed plastic waste.

A further object of the present invention is to provide a device that is versatile and easy to operate, compatible with other aspects of the plastics recycling device, and easily adjustable to meet different operational requirements.

In the utility model, the plastic electrostatic sorting system includes a rotating drum-shaped cylinder made of metal material for containing particles. The drum has an inlet for charging the material and an outlet for discharging the material. The device also has means for rotating the drum about an axis of rotation oriented such that the particles collide with each other or with the walls of the container during operation of the device, thereby triboelectrically electrifying them. A particulate removal screen assembly is provided on the outer surface of the drum to remove particulates from the interior of the drum.

The drum-shaped cylinder conveniently consists of two separate sections joined together by a multitude of mixing rods located on the inner surface of each section. The mixing rods are radially spaced and arranged longitudinally along the inner wall of the drum. The particulate filter screen member is also partially wrapped with metal tape to increase its mechanical strength.

The drum also contains a flow air flow directing member located adjacent to the particulate filter screen member to direct the air flow from the screen to prevent loose material from clogging the screen as it flows into the drum.

In addition, the drum-shaped cylinder in the plastic electrostatic sorting system of the present invention can also be a rotating drum-shaped cylinder made of metal material for containing particles. The drum has an inlet for charging the material and an outlet for discharging the material. The device also has means for rotating the drum about an axis of rotation oriented such that the particles collide with each other or with the walls of the container during operation of the device, thereby triboelectrically electrifying them. Near the outlet is located an electrostatic separation tower with conical walls and at least one pair of electrodes on both sides of the tower walls. The discharged particles fall into the tower and are separated in an electric field formed by at least one pair of electrodes.

The unit preferably also includes monitors to provide immediate feedback to the operator of the amount of waste separated in the column.

The monitor conveniently comprises an array of lasers placed on one side wall of the tower, the light from the lasers passing through the lower part of the tower, substantially perpendicular to the electrodes, and an array of photodiodes similar to the laser arrangement but placed On the other side wall of the tower corresponding to the laser. The photodiode is used to detect the intensity of the laser light emitted from the laser to the photodiode. The monitor preferably also includes an amplifying, inverting and inverting means to amplify, invert and invert the photodiode output, a multiplexing means to record the collected data and a computer to feed the recorded data into the computer and displayed on the monitor.

The apparatus also preferably includes a plurality of vanes positioned at the outlet of the drum and attached to the inner wall thereof to average the particle effluent exiting the drum through the outlet.

The apparatus also conveniently includes a funnel placed below the outlet, between the outlet and the electrostatic coarse separation column, to direct the particles away from the central location of said funnel. The funnel preferably comprises a roof-shaped structure placed inside the funnel. The roof shape structure is conveniently fitted with vanes to further direct the particles away from the center of the funnel. The funnel also conveniently contains an outlet channel fitted with a piston rod to ensure particles flow out of the outlet channel at a minimum particle velocity.

By adopting the utility model, the mixed plastic waste can be sorted by electrostatic means, and the recycling based on this has good environmental protection and economic efficiency.

Description of drawings

In order to understand the utility model more clearly, the preferred embodiment of the utility model will be described in detail by way of example, and is equipped with a picture, wherein:

Fig. 1 is a general perspective view of a particle sorting device for electrostatic separation of mixed plastic waste;

Fig. 2 is the side view of this device;

Figure 2a is a partial cross-sectional view of a tube distributing particles into a distribution funnel;

Figure 2b is an upper front view of the device;

Fig. 3 is the front view of device;

Fig. 4 is the front sectional view of drum-shaped cylinder, sees the line A-A of Fig. 2;

Fig. 4a is the front sectional view of drum-shaped cylinder, sees the line B-B of Fig. 2;

Figure 5 is a partial side sectional view of the drum-shaped cylindrical screen area;

Figure 5a is a close-up view of Figure 5 showing the gas nozzle and mesh screen;

Figure 6 is a schematic representation of the monitoring system of the separation device, and;

Figure 7 is a histogram illustrating the number of particles at an instant.

Detailed ways

As shown in Figures 1-7, Figures 1 to 7 show preferred embodiments of the present invention. An electrostatic separation device 50 for mixed plastic waste is generally indicated. The device comprises a drum-shaped cylinder 1 with an inlet 11 and an outlet 13 .

The drum is tilted and its inlet is higher than the outlet, so when the drum rotates, the charged plastic waste is transferred from the inlet to the outlet. The drum-shaped cylinder preferably also has longitudinally spaced supporting ribs 4 disposed on its outer surface. The support rib is connected to at least one drive wheel 7, preferably made of rubber or coated with rubber to increase friction. More conveniently, in order to increase the frictional force between the drum-shaped cylinder 1 and the driving wheel 7, a pair of driving wheels, whose rotation axis is parallel to the rotation axis of the drum-shaped cylinder, are respectively placed through the drum-shaped cylinder The sides of the vertical face of the center. At least one drive wheel is propelled by a drive means 8, for example an electric motor. The drum is preferably divided into several parts, such as a first part 3 and a second part 5 . The two parts are connected by an internal mixing rod 16' which lines up and supports the different parts while also mixing the waste. The mixing rods are radially spaced and arranged longitudinally along the inner wall of the drum-shaped cylinder, as shown in Figures 4 and 5. At least three of the mixing rods are rationally arranged and support various parts of the drum to form a continuously elongated drum. The drum 1 is preferably placed on top of a frame 9 to sufficiently raise the drum 1 from the ground.

Immediately outside and between the two parts is a mesh screen 10, as shown in detail in Figures 5 and 5a. The mesh width is about 5 to 10 cm. The size of the mesh screen is approximately selected according to the actual application, which will be described in more detail below. The metal strip 12 is fixed to the outer surface of the drum-shaped cylindrical part by reasonable fastening means such as screwing, gluing or welding. Metal straps provide mechanical strength and prevent piercing the mesh screen. Immediately above the drum is an air flow directing device 14, such as a gas nozzle, connected to a pressurized gas source (not shown). The air flow is directed over the screen 10 to prevent loose material flowing into the drum from clogging the screen. In one embodiment of the present invention, an electrostatic particle separation tower 20' is placed directly below the drum-shaped cylinder for separating the fine materials filtered through the screen, and its parameters are optimized for fine particles. Alternatively, if the number of particles makes separation uneconomical, the particles are collected and discarded. This can be done in any suitable container, such as a plastic container or bag or the like.

An electrostatic rough separation tower 20 is installed close to the outlet 13 of the drum-shaped cylinder 1 . The electrostatic rough separation tower has at least one pair of electrodes 24, and an electric field can be formed between the two electrodes. Particles 6 falling into the electric field will enter different orbits according to their respective charges. In this way, the particles are divided into different groups, each group containing a material. This greatly contributes to the recycling and reuse of waste plastics.

After the particles have flowed out of the rotating drum 1, in order to obtain a satisfactory "curtain" of particles 6, a series of blades 6, preferably ten in number, about 10 cm in length, are attached to the outlet 13 of the drum. on the inner surface of the cylinder (see Figures 2a and 2b). Vanes can be used to average the particle flow from the outlet and disperse the particles along the length of the electrode, as shown in Figure 2b. To further minimize the velocity of the particles exiting the drum and disperse the particles in a straight line parallel to the electrodes, a funnel 30 is installed directly below the outlet of the drum between the outlet and the electrostatic coarse separation tower 20 . The funnel contains an outflow channel 33 which is open at the bottom. The size of the opening is preferably 8-10 mm wide. The size of the opening is determined by the largest particle size found in the input waste material, specifically twice that largest particle size. Inside the funnel 30 is a roof-shaped formation 34 to which small vanes 32 are secured to direct the particles away from the center of the funnel, where the particles exit the drum-shaped cylinder along a line parallel to the electrode 24. . The pattern of blades is illustrative only, as there are other means of distributing particles in a desired manner. A small rod 36, located approximately half way from the funnel to the exit channel, ensures a minimum particle velocity as the particles leave the funnel and fall non-linearly.

In order to obtain satisfactory instant feedback on the operation of the electrostatic rough separation column 20, the overall structure of the apparatus 50 is illustrated schematically in FIGS. In order to demonstrate the distribution of the particles 6 as they fall through the electrostatic field in the electrostatic rough separation tower 20, Figure 6 shows in diagram form the device designed and constructed. An electrostatic field is formed between at least one pair of electrodes 24 . The electrodes are located on opposite side walls of the tower. A monitoring device preferably comprising an array of lasers 22 is located on one side of the tower wall. Light from the laser passes through the lower portion of the tower, substantially perpendicular to the electrodes 24 . Sixteen individual lasers are preferably used, although the actual number will depend on, among other factors, the volume of the tower. The intensity of the light reaching the farthest side wall of the tower is detected by an array of photodiodes 23 arranged similarly to the lasers but placed on the other side wall of the tower corresponding to the lasers. The output of the photodiode is amplified, inverted and converted to eight digits by a control unit. A multiplexing tool is used to record the data, and the recorded data is input to the computer and displayed on the monitor, as shown in the histogram in Figure 7. The height of the squares indicates the amount of material falling through the section of the electrostatic rough separation column, and the histogram form can also be used to assess separation efficiency on a continuous basis.

Particulate Removal Mesh screens have many advantages over previous technologies. Because the material is divided into two parts based on size and then electrostatically separated, the quality and total amount of separation is improved. Furthermore, because the two parts are separated in different electrostatic towers, the electric field can be optimized according to the particle size, so that a better separation effect can be achieved. Since the particles are filtered out before entering the electrostatic rough separation tower 20, contamination of the electrodes in the separation tower is minimized. The vanes 16 at the outlet 13 of the drum 1 allow the material to continuously flow out of the drum without sudden bursts of material. The internal structure of the funnel, wherein the roof-shaped inner part 34 prevents the particles from directly entering the electrostatic coarse separation tower from the drum-shaped cylinder outlet, reduces the velocity of the particles entering the tower. Vanes 32 inside the funnel direct the material into the tower along a line parallel to the electrodes. Thus, increased separation does not degrade device performance due to large numbers of particles falling into a confined space, with the result that a particle carries a charge that protects its neighbors from the overall electric field required for proper separation. An immediate indication of separation efficiency is given to the operator, from which the operator can determine whether the unit is functioning properly. For example, a two-part mixture of 50-50 would have a bimodal distribution, whereas a 95-5 mixture would have a Gaussian distribution with one side with a higher peak. If the displayed profile deviates from the expected profile, the operator should look for the reason for the deviation. Storing the separation pattern that successfully separated a particular mixture allows the operator to recall that pattern and compare with the current pattern obtained to ensure that the unit is functioning properly. This is very important for separating special materials after some materials have been separated. The thinning of the laser beam is proportional to the amount of material that falls between the laser and the detector. Thus, the scaled histogram can be used to total the amount of material processed by the separation device. In turn, the amount of separation can be calculated based on the position of the separator used to establish the product flow.

In the separation process described, the particles are fed into a slightly inclined rotating drum-shaped cylinder. Particles colliding with each other lead to charge transfer through contact charging. Because of the inclination, the particles gradually move towards the outlet at the end of the drum and are all charged. Then it falls vertically into the electrostatic rough separation tower, where the electric field is formed by high voltage electrodes. After entering the electric field, the particles will move to the positive and negative electrodes according to the polarity of the charge they carry, and realize separation according to the material type.

1. Particle size, particle size range and microparticles:

The separation process depends on the ability of the charged particles to be drawn in over the distance by the electrical level within the separation tower. Measurements show that the greater the charge-to-mass ratio, the farther the particles are moved by the electric field. The charge available to a particle depends on the surface area, which is the square of the particle size, and the mass depends on the volume, which is the volume of the particle size. The charge-to-mass ratio increases with decreasing particle size. Smaller particles are more easily moved by electricity.

In particular, voltages exceeding 60 kV are difficult to maintain. This limits the practical electric field to 400 kV/m with an electrode separation of 300 mm. Because plastics have a density, typically close to 1 gram per cubic centimeter, the upper limit of the size of particles that can move significantly in this electric field is 10 millimeters. This clearly defines the largest particle size during separation. The exception is plastic foam particles, such as polyurethane, which have densities as low as 1/10. For this material, the upper particle size limit is about 20 mm.

At the lower limit, finer particles, less than 100 microns, dissimilarly charged particles stick together due to electrostatic forces between the particles. It is very difficult to separate them by mechanical means such as hitting a surface. The stuck particles move in the electric field, as if they were a single particle, with a charge equal to the sum of the positive and negative charges—nearly zero. Clearly, the separation of such particles is ineffective. In this way, the separation process can be adapted for particles in the range of 100 microns to 10 mm.

Ideal feed materials for separation processes are materials with a narrow particle size range. In this case, each particle can carry substantially the same charge, and the charge-to-mass ratio of each particle will be very close. This allows the particles of the same plastic to be horizontally arranged within a relatively narrow range in the separation tower. Particles of the same plastic but different sizes will have a range of charge-to-mass ratios, and the range of horizontal arrangements will be wider and the separation effect will be poor. In fact, a particle size range of about 3 mm, such as 2 to 6 mm, can achieve a better separation effect.

In order to obtain high purity separation results, particulates must be removed from the waste material mixture. Small particles of plastic charged with one polarity attach to larger particles of dissimilar plastic with an opposite charge. Mechanical force is also unable to remove these fine particles, so they can be carried into the product stream by larger particles reducing the purity obtained. To obtain high-purity separations, these small particles must be removed, for example by gas elutriation or screening, prior to the separation process.

2. wet

The separation process depends on contact electrification and triboelectric charging, where the charges of two different non-conductive materials are transferred during contact. The material must be dry enough to make the surface less conductive. Although conductive materials also become charged when in contact, most of the transferred charge leaks back when separated. In general, conductive materials are less charged than insulating materials. Moisture, manifested in the form of high humidity in the material or the presence of wet substances, increases the conductivity of the surface thereby reducing or completely destroying contact electrification. In fact, the material must be exposed to a humidity of 50% R.H. or less in order to be properly charged. The test results show that the separation effect will decrease when the humidity is greater than 50% R.H. Humidity must be controlled around the drum and the material entering the drum must be dry. The higher humidity around the drum can be avoided by heating the material to 10°C immediately before separation. In this case, the short residence time of the material inside the drum is not sufficient for its surface to become wet and thus destroy the electrification.

3. Charging time

The charging process depends on the number of contacts (thousands), so any particle surface charge density amount will not be much different from the average charge density. This is critical to the quality of the separation. Charging is a self-limiting process in which already fully charged particles do not undergo charge transfer upon contact. In fact, a 0.5 to 2 minute stay inside the drum cylinder at 10-20 rpm is enough to obtain a uniform and adequate charge.

4. Drum cylinder shape and material

Particle charging occurs when two dissimilar materials come into contact without an external electric field. If an electric field is present and its direction is opposite to the direction of charge transfer, the charge will not transfer, or if the electric field is strong enough, the charge will transfer in the opposite direction. Therefore, to be successful, charging must take place without an electric field. This is the case in the conductive drum-shaped cylinder.

Therefore, the drum is preferably made of metallic material. If the drum is made of insulating material, a large charge can build up inside. This would suddenly invalidate the insulation and cause a large charge spike which would be fatal to anyone touching the drum cylinder. For the same reason, any conductive drum must be carefully grounded. At the same time, the charge carried by the positively charged particles in the insulating drum must be completely offset by the charge carried by the negatively charged particles, that is, no charge can be generated or destroyed. On the other hand, in a grounded conductive drum, the charge does not need to be neutralized because the charge will be transferred to the particles through the drum. When removing a small amount of another material from a very pure material, the primary material becomes charged, improving the separation, which is critical.

5. Overcharging:

For materials with an average particle size of less than 2 mm, and for materials that are highly charged, such as PTFE in polyethylene or the equivalent PVC, the charging will be so intense that the particles crowd together and are difficult to separate. The solution is to reduce the time spent inside the charging drum to 15-30 seconds.

6. Mixture:

For a 50-50 mixture of two components, each material is charged approximately equally. The separated materials form a bimodal distribution at the bottom of the separation tower, with most positively charged materials falling on the negative electrode side and negatively charged materials falling on the positive electrode side. If the proportions of the two components are very different, such as a 95-5 mixture, the lesser component will carry a large amount of charge, because each of its charges is almost always in contact with a particle of the major component, and the major component has little charge because each of its charges A particle is always in contact with the same material so charge transfer does not occur. In this way, minor components, if positively charged, are drawn away by the negative electrode, while the major components fall very close to the central axis of the tower.

For mixtures containing more than two components, there will always be either a predominantly negatively charged material or a predominantly positively charged material. However, when the primary charged material is removed from the mixture, the remaining material is recharged inside the drum with a completely different polarity. For example, in a mixture containing polyethylene (PTFE), polytetrafluoroethylene (PE) and polyvinyl chloride (PVC), PTFE will be negatively charged and attracted by the positive electrode, while PE and PVC will be positively charged and absorbed by the negative electrode. However, after PTFE is removed, PVC becomes negatively charged while PE continues to be positively charged. In this way, complex mixtures can be separated through multiple passes through the separation process, as the charge changes as the components are removed.

7. Electric field entry parameters:

Particles falling from rest will become faster and faster in the air due to gravity. To maximize the effect of a horizontal electric field on a charged particle, the velocity of the particle as it passes through the field should be minimal. Ideally, particles should enter the electric field starting from rest. Finally, a funnel was designed to force the particles to move back and forth and slide along an inclined plane after leaving the drum before entering the electric field. This minimizes the velocity of the particles before entering the electric field. At the same time, all particles should enter the electric field along the axis between the two electrodes. If too many particles enter the electric field at any one point between the two electrodes simultaneously, the device's capabilities will be limited. These charged particles cause space charges, which reduce the electric field and reduce separation efficiency. The same surface used to slow down the particles can also be used to guide the particles, so the particles enter the electric field along a line parallel to the electrodes. In this way, a separation tower with a length of one meter can carry out a separation capacity of 1 metric ton per hour.

It should be appreciated that the foregoing description relates to preferred embodiments, by way of example only. Many variations of the invention will be obvious to those skilled in the relevant art, and such obvious variations are within the scope of the invention as described and claimed, whether explicitly described or not.

For example, imagine replacing the combination of metal belt and separate mesh with an integral belt with mesh screens around its circumference. Also, although only two sections are described that make up the drum, there could be three or more sections. Correspondingly, the connection points of the added parts should also have mesh screens. A screen further down in the direction of material flow removes some coarser particles than the screen preceding it. A number of small rods suitably placed across the opening of the funnel further separates the particles along the intersection of the openings. Although parallel light produced by lasers is optimal, beams of light can also be generated with lamps and lenses.

Claims (11)

1. plastic static sorting system is characterized in that described system comprises:

The rotation drum-like cylinder, make by metal material, be used for transmitting particle (6), described drum-like cylinder has an inlet and an outlet, described drum-like cylinder slight inclination so that described outlet a little less than described inlet;

The parts of rotation drum-like cylinder, in order to described particle can collide mutually and with drum-like cylinder inwall collision, thereby frictional electrification and is moved to described outlet from described inlet;

An electrostatic separation tower is equipped with at least one pair of electrode on its corresponding sidewall, so that separate the described particle that falls into described tower from described drum-like cylinder in the electric field that this described at least one pair of electrode forms; And

Monitoring device, the quantity of the particle that in the described tower of operator's immediate feedback, is separating.

2. according to the described plastic static sorting system of claim 1, it is characterized in that described monitoring device comprises:

One row's laser instrument places on described tower one sidewall, and the light that laser instrument sends is guided through the bottom of described tower, and abundant vertical electrode; And row's photodiode is arranged similar with described laser instrument but is placed another sidewall of the tower corresponding with it, and described photodiode is used to monitor light intensity, and this light is issued to photodiode from described laser instrument.

3. plastic static sorting system according to claim 2 is characterized in that described monitoring device also comprises:

Amplification, paraphase and a reforming unit are with amplification, paraphase and the output of conversion photodiode;

A multiplexing unit, the data of collecting with record; With a computer, record data are transfused to this computer and show on display.

4. plastic static sorting system according to claim 1 is characterized in that described system also comprises a device of giving the material slightly heated before entering described drum-like cylinder, to reduce material humidity.

5. plastic static sorting system according to claim 1 is characterized in that described system also comprises particulate filtering mesh screen, and the part around the drum-like cylinder before the described outlet can allow fine particle leach in drum-like cylinder before reaching described outlet.

6. plastic static sorting system according to claim 5, it is characterized in that described drum-like cylinder also comprises a moving air stream guiding device, place particulate filtering mesh screen next door, the air-flow that flows out from described mesh screen with guiding prevents that described mesh screen from being flowed into the discrete material obstruction of described drum-like cylinder.

7. plastic static sorting system according to claim 1 is characterized in that described drum-like cylinder contains a large amount of mixing rods, vertically is provided with along described drum-like cylinder inwall.

8. plastic static sorting system according to claim 1 is characterized in that described device also comprises a funnel, places described outlet below, between described outlet and described electrostatic separation tower.

9. plastic static sorting system according to claim 8 is characterized in that described system also comprises a roof shape structure, places on the described funnel to guide particle away from described hopper centre.

10. plastic static sorting system according to claim 8 is characterized in that described funnel also comprises an exit passageway that bar is housed to reduce the speed that particle leaves described exit passageway.

11. plastic static sorting system according to claim 9 is characterized in that described funnel also comprises an exit passageway that bar is housed to reduce the speed that particle leaves described exit passageway.

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