Electrostatic separation device

Abstract

Provided is an electrostatic sorting device including a feeding unit, an electrifying unit, an electrostatic separating unit, a collection container, a circulating unit, and a control unit. In this invention, the feeding unit feeds a material to be sorted, which includes multiple types of objects with different electrification characteristics. The electrifying unit electrifies the multiple types of objects. The electrostatic separating unit has a plurality of electrodes with a predetermined voltage applied thereto, and the multiple types of objects falling between the plurality of electrodes are attracted toward one of the electrodes according to the electrification state. The collection container is disposed below the plurality of electrodes and is divided into a plurality of areas by partitions. The circulating unit circulates a portion of the sorted objects from the collection container to the electrifying unit. The control unit determines a sorting condition on the basis of first and second evaluation results, the first evaluation result being the result of evaluating the composition ratio and amount fed of objects fed into the electrifying unit from the feeding unit, the second evaluation result being the result of evaluating the composition ratio and amount fed of objects fed into the electrifying unit from the circulating unit.

Description

Technical Field

[0001] This disclosure relates to an electrostatic separation device.

Background Art

[0002] Conventionally, a technique for separating a mixture containing multiple types of objects (e.g., plastic pieces) by the type of object is known. In this separation technique, for example, there is an electrostatic separation device that charges multiple types of objects contained in a mixture and separates a specific object as an object to be recycled by electrostatic separation. As a technique for improving the accuracy of separation by electrostatic separation, for example, the electrostatic separation device described in Patent Document 1 is known.

[0003] The above electrostatic separation device includes a raw material composition evaluation unit that measures the composition of mixed plastics, and a circulation unit that sends either the separated first plastic or the second plastic to the charging unit. The circulation unit switches whether to send the separated first plastic or the separated second plastic to the charging unit based on the measurement result by the raw material composition evaluation unit.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when an object is sent to the charging unit by the circulation unit, the composition ratio and the input amount of the objects input to the charging unit change. For this reason, the separation conditions (e.g., the position of the partition, the intensity of the electrostatic field, etc.) may deviate from the appropriate range, and the purity and recovery rate of the recovered objects may decrease.

[0006] This disclosure has been made in view of the above-mentioned problems, and aims to provide an electrostatic sorting device that can appropriately set sorting conditions even when objects are circulated. [Means for solving the problem]

[0007] To solve the above problems, the electrostatic sorting apparatus according to the present disclosure includes: an input unit for inputting a material to be sorted containing multiple types of objects with different charging characteristics; a charging unit for charging the multiple types of objects contained in the material to be sorted; an electrostatic separation unit having a pair of electrodes to which a predetermined voltage is applied, which pulls the multiple types of objects falling between the multiple electrodes toward one of the electrodes according to their charging state; a collection container positioned below the multiple electrodes and divided into multiple regions by partitions; a circulation unit for circulating a portion of the sorted objects from the collection container to the charging unit; and a control unit for determining sorting conditions. The control unit determines the sorting conditions based on a first evaluation result, which is the result of evaluating the composition ratio and input amount of objects input from the input unit to the charging unit, and a second evaluation result, which is the result of evaluating the composition ratio and input amount of objects input from the circulation unit to the charging unit. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide an electrostatic sorting device that can appropriately set sorting conditions even when objects are circulated. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram showing an electrostatic separation apparatus according to an embodiment. [Figure 2] This is a flowchart showing the electrostatic separation method according to an embodiment. [Modes for carrying out the invention]

[0010] The electrostatic sorting apparatus according to the embodiment will be described below with reference to the drawings.

[0011] As shown in Figure 1, the electrostatic sorting apparatus 1 according to this embodiment comprises an input unit 10, a charging unit 20, a transport unit 30, an electrostatic separation unit 40, a recovery container 50, a circulation unit 60, and a control unit 70.

[0012] The electrostatic separator 1 is a device for separating multiple types of objects with different electrostatic properties. "Different electrostatic properties" means that they differ in whether they become positively or negatively charged, or in how easily they become charged. For example, in the case of polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), ABS, and polyamide (PA) resins, PVC resin is the most likely to become negatively charged, and PA resin is the most likely to become positively charged. More specifically, PVC resin is the most likely to become negatively charged in the order of PVC resin, PP resin, PS resin, ABS resin, and PA resin, and PA resin is the most likely to become positively charged in the order of PA resin, ABS resin, PS resin, PP resin, and PVC resin. The objects separated by the electrostatic separator 1 are, for example, plastic pieces, food pieces, or metal pieces. However, the objects separated by the electrostatic separator 1 are not limited to these, and can be changed as appropriate if separation using differences in electrostatic properties is possible.

[0013] The charging unit 20 according to this embodiment is a cylindrical charging drum (charging cylinder). The charging unit 20 may be formed in a cylindrical shape, a polygonal prism shape, or the like. The charging unit 20 has a central axis O. A charged space I is formed inside the charging unit 20 through which the material to be sorted passes. As long as a charged space I is formed inside the charging unit 20, the inner diameter and outer diameter of the charging unit 20 may or may not be constant in the axial direction parallel to the central axis O.

[0014] The charging unit 20 is configured to be rotatable about a central axis O. By rotating about the central axis O, the charging unit 20 charges multiple types of objects passing through the charging unit 20 (charging space I). The charging space I may be provided with vane members protruding from the inner circumferential surface of the charging unit 20 toward the central axis O, or partition plates that divide the charging space I in the axial direction. The type of charging unit 20 is not limited to a charging drum and can be changed as appropriate, as long as it is possible to charge objects.

[0015] The transport unit 30 transports the material to be sorted. The transport unit 30 according to this embodiment has a first transporter 31 and a second transporter 32. The first transporter 31 transports the material to be sorted supplied from the input unit 10 to the charging unit 20. The second transporter 32 transports the material to be sorted discharged from the charging unit 20 to the electrostatic separation unit 40.

[0016] The input unit 10 is a device for inputting materials to be sorted, including multiple types of objects, into the charging unit 20. In this embodiment, the input unit 10 inputs the materials to be sorted into the charging unit 20 via the first conveyor 31. Alternatively, the input unit 10 may input the materials to be sorted directly into the charging unit 20 without going through the first conveyor 31. In this case, the electrostatic sorting device 1 does not need to have the first conveyor 31.

[0017] The electrostatic isolation unit 40 sorts multiple types of objects that have been charged by the charging unit 20 according to the charging characteristics of each object. The electrostatic isolation unit 40 according to this embodiment has multiple (pair in the illustrated example) electrodes 41 and 42 to which a predetermined voltage is applied. Hereinafter, the pair of electrodes 41 and 42 will be referred to as the first electrode 41 and the second electrode 42, respectively. The electrostatic isolation unit 40 may have multiple first electrodes 41 or multiple second electrodes 42. Also, the number of first electrodes 41 and the number of second electrodes 42 do not have to be equal.

[0018] Multiple types of objects charged by the charging unit 20 are transported by the first conveyor 31 and then fall between the first electrode 41 and the second electrode 42. Alternatively, the objects charged by the charging unit 20 may fall directly between the electrodes 41 and 42 without passing through the first conveyor 31. In this case, the electrostatic separation device 1 does not need to have the second conveyor 32.

[0019] A different voltage is applied to the first electrode 41 and the second electrode 42, for example, by means of a DC power supply. For example, a positive voltage is applied to the first electrode 41, and a negative voltage is applied to the second electrode 42. A plurality of types of objects falling between the electrodes 41 and 42 are attracted to either the first electrode 41 or the second electrode 42 according to their charged states.

[0020] The voltages applied to the electrodes 41 and 42 may be configured to be changeable. In this case, by changing the voltages applied to the electrodes 41 and 42, it becomes easier to perform appropriate sorting according to the mixing ratio of the objects to be sorted, etc.

[0021] The collection container 50 is disposed below the plurality of electrodes 41 and 42. The collection container 50 according to the present embodiment has a first partition 51 and a second partition 52. By the first partition 51 and the second partition 52, the internal space S of the collection container 50 is divided into a plurality of regions including a first collection region S1, a second collection region S2, and an intermediate region S3 located between the collection regions S1 and S2. The first collection region S1 is a region for collecting the objects attracted to the first electrode 41. The second collection region S2 is a region for collecting the objects attracted to the second electrode 42. The intermediate region S3 is a region for collecting the objects that have not been collected in either of the collection regions S1 and S2.

[0022] The positions of the partitions 51 and 52 may be configured to be changeable. In this case, by changing the positions of the partitions 51 and 52, it becomes easier to perform appropriate sorting according to the mixing ratio of the objects to be sorted, etc. The number of partitions and the number of regions can be changed as appropriate.

[0023] The circulation unit 60 circulates a part of the sorted objects from the collection container 50 to the charging unit 20. The circulation unit 60 in the illustrated example circulates the objects collected in the intermediate region S3 to the charging unit 20 via the first conveyor 31. However, the circulation unit 60 may circulate the objects collected in the collection regions S1 and S2 to the charging unit 20. Also, the circulation unit 60 may circulate the objects directly to the charging unit 20 without passing through the first conveyor 31.

[0024] The control unit 70 according to this embodiment includes an input raw material evaluation unit 71, a circulation evaluation unit 72, and an estimation unit 73. Note that the functions of the control unit 70 (input raw material evaluation unit 71, circulation evaluation unit 72, and estimation unit 73) may be realized by a CPU (Central Processing Unit) executing a program. Alternatively, it is also possible to realize the functions of the control unit 70 using hardware (including a circuit unit; circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit). Or, it is also possible to realize the functions of the control unit 70 through the cooperation of software and hardware. Also, the respective functions of the control unit 70 (input raw material evaluation unit 71, circulation evaluation unit 72, and estimation unit 73) may be realized by the same hardware as each other, or may be realized by separate hardware.

[0025] The input raw material evaluation unit 71 evaluates the composition ratio and the input amount of the object input from the input unit 10 to the charging unit 20. Hereinafter, this evaluation result is referred to as the "first evaluation result". The input raw material evaluation unit 71 outputs the first evaluation result to the estimation unit 73. As an example of a method for evaluating the composition ratio, a method of extracting a part of the input raw material and identifying the type of the object by infrared light to estimate the composition ratio can be cited. As an example of a method for evaluating the input amount, a method of installing a granule sensor at a location where the input raw material passes through to estimate the input amount can be cited. Also, a method of not evaluating the composition ratio and the input amount each time but diverting past evaluation results can be cited.

[0026] The circulation evaluation unit 72 evaluates the composition ratio and the input amount of the object input from the circulation unit 60 to the charging unit 20. Hereinafter, this evaluation result is referred to as the "second evaluation result". The circulation evaluation unit 72 outputs the second evaluation result to the estimation unit 73.

[0027] The estimation unit 73 acquires the first evaluation result output from the input raw material evaluation unit 71. The estimation unit 73 also acquires the second evaluation result output from the circulation evaluation unit 72. Based on the first and second evaluation results, the estimation unit 73 estimates the total composition ratio and total input amount of the material introduced into the input unit 10 from both the input unit 10 and the circulation unit 60. Specifically, "total composition ratio" refers to the composition ratio of the material introduced into the charging unit 20 from the input unit 10 and the material introduced into the charging unit 20 from the circulation unit 60. "Total input amount" refers to the sum of the amount of material introduced into the charging unit 20 from the input unit 10 and the amount of material introduced into the charging unit 20 from the circulation unit 60 (input amount).

[0028] An example of estimation by the estimation unit 73 is shown below. The following example shows how ABS resin pieces and polystyrene (PS) resin pieces contained in the material to be sorted are sorted by the electrostatic sorting device 1. <First evaluation results by the Input Raw Material Evaluation Department 71> Composition ratio ABS:PS=50:50 Input amount 500kg / h <Second evaluation results by the Circulation Evaluation Unit 72> Composition ratio ABS:PS=90:10 Input amount 100kg / h <Estimated by Estimation Unit 73> Total composition ratio ABS:PS=57:43 Total input amount 600kg / h

[0029] The control unit 70 determines the sorting conditions based on the estimation results from the estimation unit 73. "Sorting conditions" refers to the conditions (parameters) that affect the sorting of objects by the electrostatic sorting device 1. Examples of sorting conditions include the positions of the partitions 51 and 52, and the voltage applied to the electrodes 41 and 42.

[0030] The control unit 70 controls the electrostatic separator 1 based on the determined sorting conditions. In other words, the control unit 70 applies the determined sorting conditions to the electrostatic separator 1. For example, the control unit 70 controls at least one of the positions of the partitions 51 and 52 and the voltage applied to the electrodes 41 and 42 based on the determined sorting conditions.

[0031] Furthermore, the control unit 70 may directly determine the sorting conditions based on the first and second evaluation results without going through estimation by the estimation unit 73. In other words, the control unit 70 does not need to estimate the total composition ratio and the total input amount. In this case, the control unit 70 does not need to have the estimation unit 73.

[0032] The electrostatic sorting method according to the embodiment will be described below with reference to Figure 2.

[0033] As shown in Figure 2, the electrostatic sorting method according to this embodiment includes an input raw material evaluation step ST1, a sorting step ST2, a recycled raw material evaluation step ST3, an estimation step ST4, and a sorting condition adjustment step ST5.

[0034] In the input material evaluation process ST1, the input material evaluation unit 71 evaluates the composition ratio and input quantity of the material to be introduced from the input unit 10 to the charging unit 20. The input material evaluation unit 71 outputs the resulting first evaluation result to the estimation unit 73.

[0035] In sorting step ST2, the electrostatic separator 1 sorts the objects that have been fed from the input section 10 into the charging section 20. In other words, multiple types of objects are sorted into one of the multiple regions S1 to S3 of the recovery container 50 according to their charge state. After sorting step ST2 is performed, some of the sorted objects are returned to the charging section 20 by the circulation section 60. For example, objects recovered in the intermediate region S3 are returned to the charging section 20 by the circulation section 60.

[0036] In the recycled raw material evaluation process ST3, the recycling evaluation unit 72 evaluates the composition ratio and amount of material introduced from the circulation unit 60 to the charging unit 20. The recycling evaluation unit 72 outputs the second evaluation result, which is the result of this evaluation, to the estimation unit 73.

[0037] In estimation step ST4, the estimation unit 73 estimates the total composition ratio and total input amount based on the first evaluation result and the second evaluation result.

[0038] In the sorting condition adjustment step ST5, the control unit 70 determines the sorting conditions based on the estimated total composition ratio and total input amount. Then, the control unit 70 controls the electrostatic separator 1 based on the determined sorting conditions. Based on the sorting conditions thus controlled, the sorting step ST2 is performed again. Thereafter, steps ST2 to ST5 are repeated. Note that not only steps ST2 to ST5, but also the input raw material evaluation step ST1 may be repeated. In other words, steps ST1 to ST5 may be repeated.

[0039] As described above, the electrostatic sorting apparatus according to this embodiment includes an input unit 10 for inputting material to be sorted containing multiple types of objects with different charging characteristics, a charging unit 20 for charging multiple types of objects contained in the material to be sorted, an electrostatic separation unit 40 having multiple electrodes 41, 42 to which a predetermined voltage is applied, which pulls multiple types of objects falling between the multiple electrodes 41, 42 towards one of the electrodes 41, 42 depending on their charging state, a recovery container 50 positioned below the multiple electrodes 41, 42 and divided into multiple regions S1 to S3 by partitions 51, 52, a circulation unit 60 for circulating a portion of the sorted objects from the recovery container 50 to the charging unit 20, and a control unit 70 for determining sorting conditions. The control unit 70 determines sorting conditions based on a first evaluation result, which is the result of evaluating the composition ratio and input amount of objects input from the input unit 10 to the charging unit 20, and a second evaluation result, which is the result of evaluating the composition ratio and input amount of objects input from the circulation unit 60 to the charging unit 20.

[0040] With this configuration, the sorting conditions are determined not only using the first evaluation result, but also using the second evaluation result, which is the result of evaluating the composition ratio and amount of material introduced from the circulation unit 60 to the charging unit 20. Therefore, even when the material is circulated, it is possible to set appropriate sorting conditions. By setting appropriate sorting conditions, the purity and recovery rate of the material can be improved.

[0041] Furthermore, the control unit 70 may estimate the total composition ratio and total input amount of the objects introduced into the charging unit 20 from both the input unit 10 and the circulation unit 60, based on the first and second evaluation results. With this configuration, the sorting conditions can be appropriately adjusted using the total composition ratio and total input amount.

[0042] Although embodiments have been described above, this disclosure is not limited to the embodiments described above, and can be freely modified without departing from the spirit of this disclosure.

[0043] Furthermore, each component of the electrostatic separation device 1 described above has a computer system inside. The processing in each component of the electrostatic separation device 1 may be performed by recording a program for realizing the functions of each component of the electrostatic separation device 1 onto a computer-readable recording medium, loading the program recorded on this recording medium into the computer system, and executing it. Here, "loading the program recorded on the recording medium into the computer system and executing it" includes installing the program into the computer system. Here, "computer system" includes the OS and hardware such as peripheral devices.

[0044] Furthermore, "computer system" may include multiple computer devices connected via a network including the Internet or communication lines such as WANs, LANs, and dedicated lines. "Computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Thus, the recording medium storing the program may be a non-transient recording medium such as a CD-ROM.

[0045] Furthermore, the recording medium also includes internal or external recording media accessible from the distribution server for distributing the program. The program may be divided into multiple parts, each downloaded at a different time, and then combined using the various configurations provided by the electrostatic sorting device 1. The distribution servers distributing each of the divided programs may also be different. Moreover, "computer-readable recording media" includes volatile memory (RAM) within a computer system that acts as a server or client when the program is transmitted over a network, which retains the program for a certain period of time. The program itself may also be intended to implement some of the functions described above. Furthermore, the program may be a so-called differential file (differential program) that can implement the functions described above in combination with a program already recorded in the computer system. [Explanation of symbols]

[0046] 1...Electrostatic separation device 10...Input section 20...Charging section 40...Electrostatic separation section 41...First electrode 42...Second electrode 50...Recovery container 51...First partition 52...Second partition 60...Circulation section 70...Control section

Claims

1. An input section into which materials to be sorted, containing multiple types of objects with different electrostatic properties, A charging unit that charges multiple types of objects contained in the material to be sorted, An electrostatic isolation unit having multiple electrodes to which a predetermined voltage is applied, which attracts multiple types of objects falling between the multiple electrodes to one of the electrodes depending on their charge state, A collection container is positioned below the aforementioned plurality of electrodes and is divided into multiple regions by partitions, A circulation unit that circulates a portion of the sorted object from the collection container to the charging unit, It has a control unit for determining sorting conditions, The control unit, The first evaluation result is the result of evaluating the composition ratio and amount of the object introduced from the input section to the charging section, Based on the second evaluation result, which is the result of evaluating the composition ratio and amount of material introduced from the circulation unit to the charging unit, the sorting conditions are determined. Electrostatic sorting device.

2. Based on the first and second evaluation results, the control unit estimates the total composition ratio and total input amount of the material introduced into the charging unit from both the input unit and the circulation unit. The electrostatic sorting apparatus according to claim 1.

3. An input section for inputting materials to be sorted, which include multiple types of objects with different electrostatic properties, A charging unit that charges multiple types of objects contained in the material to be sorted, An electrostatic isolation unit having multiple electrodes, which attracts multiple types of objects falling between the multiple electrodes to one of the electrodes depending on their charge state, A circulation unit for circulating a portion of the object separated by the electrostatic isolation unit, It has a control unit for determining sorting conditions, The control unit, The composition ratio and quantity of the object introduced from the input section to the charging section, The sorting conditions are determined based on the composition ratio and quantity of the material introduced from the circulation unit to the charging unit. Electrostatic sorting device.

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