Electrostatic separation method and electrostatic separator

Abstract

This electrostatic sorting method includes a charging step, a calculation step, a computation step, and an adjustment step. In the charging step, a plurality of kinds of objects included in a material to be sorted are charged by being passed through a charging cylinder. In the calculation step, the charge amounts and weights of the plurality of kinds of objects charged in the charging step are measured, and the specific charges thereof are calculated. In the computation step, at least one of the rotational speed and the angle of inclination of the charging cylinder is computed on the basis of the specific charges calculated in the calculation step. In the adjustment step, at least one of the rotational speed and the angle of inclination of the charging cylinder is adjusted on the basis of the computation result in the computation step.

Description

Technical Field

[0001] The present disclosure relates to an electrostatic separation method and an electrostatic separation device.

Background Art

[0002] Patent Document 1 discloses an electrostatic separation device that triboelectrically charges a material to be separated containing a plurality of types of objects (plastic pieces) and separates each charged object by an electrostatic field.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The state of the material to be separated (input amount, composition ratio, shape, moisture content, etc.; hereinafter simply referred to as "the state of the material to be separated") can vary. When the state of the material to be separated varies, the ease of charging of the objects also varies. Here, for example, when the material to be separated becomes difficult to charge, the charging time is insufficient, and the purity of the separated objects may decrease. Also, when the charging time is excessive, the throughput per unit time becomes low, which may lead to a decrease in processing efficiency.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide an electrostatic separation method and an electrostatic separation device capable of maintaining the accuracy and efficiency of separation even when the state of the material to be separated varies.

Means for Solving the Problems

[0006] To solve the above problems, the electrostatic separation method according to the present disclosure includes a charging step of charging a plurality of types of objects included in a material to be separated by passing them through a charging tube, a calculating step of measuring the charge amount and weight of the plurality of types of objects charged in the charging step and calculating the specific charge, a calculating step of calculating at least one of the rotation speed and the inclination angle of the charging tube based on the specific charge calculated in the calculating step, and an adjusting step of adjusting at least one of the rotation speed and the inclination angle of the charging tube based on the calculation result in the calculating step.

[0007] To solve the above problems, the electrostatic separation device according to the present disclosure includes a charging tube that charges a plurality of types of objects included in a material to be separated, a calculating unit that calculates the specific charge based on the measured values of the charge amount and weight of the plurality of types of objects charged by the charging tube, a calculating unit that calculates at least one of the rotation speed and the inclination angle of the charging tube based on the specific charge calculated by the calculating unit, and a control unit that adjusts at least one of the rotation speed and the inclination angle of the charging tube based on the calculation result by the calculating unit.

Advantages of the Invention

[0008] According to the present disclosure, it is possible to provide an electrostatic separation method and an electrostatic separation device capable of maintaining the accuracy and efficiency of separation even when the state of the material to be separated fluctuates.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] Hereinafter, the electrostatic separation device according to the embodiment will be described with reference to the drawings.

[0011] As shown in FIG. 1, the electrostatic separation device 1 according to the present embodiment includes a charging unit 10, a charging lamp 20, a conveying unit 30, an electrostatic separation unit 40, a collection container 50, an arithmetic / control unit 60 (a calculation unit, an arithmetic unit, a control unit, a saturation inclination angle acquisition unit), a first measurement unit 71, and a second measurement unit 72.

[0012] The electrostatic separation device 1 is a device for separating a plurality of types of objects having different charging characteristics. "Having different charging characteristics" means that the object is charged either positively or negatively differently, or the ease of charging is different, etc. For example, in the case of polyvinyl chloride (PVC) resin, polypropylene (PP) resin, polystyrene (PS) resin, ABS resin, and polyamide (PA) resin, the PVC resin is most likely to be negatively charged, and the PA resin is most likely to be positively charged. More specifically, in the order of PVC resin, PP resin, PS resin, ABS resin, PA resin, it is easier to be negatively charged, and in the order of PA resin, ABS resin, PS resin, PP resin, PVC resin, it is easier to be positively charged. The objects separated by the electrostatic separation device 1 are, for example, plastic pieces, food pieces, or metal pieces, etc. However, the objects separated by the electrostatic separation device 1 are not limited to these, and can be appropriately changed as long as separation using the difference in charging characteristics is possible.

[0013] The charging lamp 20 is formed in a cylindrical shape. The charging lamp 20 may be formed in a cylindrical shape, a polygonal prism shape, etc. The charging lamp 20 has a central axis O. Inside the charging lamp 20, a charging space I through which the material to be separated passes is formed. If the charging space I is formed inside the charging lamp 20, the inner diameter and outer diameter of the charging lamp 20 may be constant or not constant in the axial direction parallel to the central axis O.

[0014] The charging tube 20 is configured to be rotatable about the central axis O. By rotating about the central axis O, the charging tube 20 charges a plurality of types of objects passing through the charging tube 20 (charging space I). In the charging space I, a blade member protruding from the inner peripheral surface of the charging tube 20 toward the central axis O, a partition plate for axially partitioning the charging space I, or the like may be provided.

[0015] The charging tube 20 is configured to be able to change the rotation speed and the tilt angle. Here, the "rotation speed" means the speed (angular velocity ω) of the rotation of the charging tube 20 about the central axis O. The "tilt angle" means the tilt angle θ of the central axis O of the charging tube 20 with respect to the horizontal direction H perpendicular to the direction of gravity acting on the gravity.

[0016] The charge amount of the object changes according to the rotation speed and the tilt angle of the charging tube 20. Fig. 2 shows an example of the relationship between the tilt angle of the charging tube and the specific charge. The specific charge is a value (charge / weight) obtained by dividing the charge (charge amount) of the object by the weight of the object. The "average specific charge" in the figure means the average value of the specific charge.

[0017] As shown in Fig. 2, when the tilt angle of the charging tube 20 is decreased, the specific charge (charge amount) of the object tends to increase. This is because the staying time of the material to be separated inside the charging tube 20 (charging space I) becomes longer. On the other hand, when the tilt angle of the charging tube 20 is decreased, the processing speed by the electrostatic separation device 1 decreases (becomes slower). This is because the amount of the material to be separated per unit time that can be introduced into the charging tube 20 decreases.

[0018] Conversely, when the tilt angle of the charging tube 20 is increased, the specific charge (charge amount) of the object tends to decrease. This is because the staying time of the material to be separated inside the charging tube 20 (charging space I) becomes shorter. On the other hand, when the tilt angle of the charging tube 20 is increased, the processing speed by the electrostatic separation device 1 improves (becomes faster). This is because the amount of the material to be separated per unit time that can be introduced into the charging tube 20 increases.

[0019] As shown in FIG. 1, the conveying unit 30 conveys the material to be sorted. The conveying unit 30 according to the present embodiment includes a first conveyor 31 and a second conveyor 32. The first conveyor 31 conveys the material to be sorted supplied from the input unit 10 to the charging lamp 20. The second conveyor 32 conveys the material to be sorted discharged from the charging lamp 20 to the electrostatic separation unit 40.

[0020] The input unit 10 is a device for inputting the material to be sorted including a plurality of types of objects into the charging lamp 20. The input unit 10 according to the present embodiment inputs the material to be sorted into the charging lamp 20 via the first conveyor 31. Note that the input unit 10 may directly input the material to be sorted into the charging lamp 20 without passing through the first conveyor 31. In this case, the electrostatic sorting device 1 may not have the first conveyor 31.

[0021] The electrostatic separation unit 40 sorts a plurality of types of objects charged by the charging lamp 20 according to the charging characteristics of each object. The electrostatic separation unit 40 according to the present embodiment includes a first electrode 41 and a second electrode 42. A plurality of types of objects charged by the charging lamp 20 are conveyed by the first conveyor 31 and then fall between the first electrode 41 and the second electrode 42. Note that the objects charged by the charging lamp 20 may directly fall between the electrodes 41 and 42 without passing through the first conveyor 31. In this case, the electrostatic sorting device 1 may not have the second conveyor 32.

[0022] For example, different voltages are applied to the first electrode 41 and the second electrode 42 by 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 are attracted to either the first electrode 41 or the second electrode 42 according to their charged states. Note that the electrostatic separation unit 40 may have a plurality of first electrodes 41 or a plurality of second electrodes 42. Also, the number of the first electrodes 41 and the number of the second electrodes 42 do not have to be equal.

[0023] The recovery container 50 is disposed below the electrodes 41 and 42. The recovery 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 recovery container 50 is divided into a plurality of regions including a first recovery region S1, a second recovery region S2, and an intermediate region S3 located between the recovery regions S1 and S2. The first recovery region S1 is a region for recovering the objects attracted to the first electrode 41. The second recovery region S2 is a region for recovering the objects attracted to the second electrode 42. The intermediate region S3 is a region for recovering the objects that have not been recovered in any of the recovery regions S1 and S2.

[0024] 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. The number of partitions and the number of regions can be changed as appropriate. Also, the recovery container 50 may not have the partitions 51 and 52. In this case, a plurality of recovery containers 50 may be provided.

[0025] The weight measurement unit 71 measures the weight of the charged objects discharged from the charging tube 20. The weight measurement unit 71 may measure the weight of all the objects discharged from the charging tube 20. Alternatively, the weight measurement unit 71 may measure the weight of a part of the objects discharged from the charging tube 20. That is, sampling of the objects discharged from the charging tube 20 may be performed, and the weight measurement unit 71 may measure the weight of the sampled objects. The weight measurement unit 71 outputs the measured weight value to the arithmetic and control unit 60.

[0026] The charge measurement unit 72 measures the charge (charge amount) of the object after charging, which is discharged from the charging tube 20. The charge measurement unit 72 may measure the charge for all the objects discharged from the charging tube 20. Alternatively, the charge measurement unit 72 may measure the charge for a part of the objects discharged from the charging tube 20. That is, sampling of the objects discharged from the charging tube 20 is performed, and the charge measurement unit 72 may measure the charge for the sampled objects. The charge measurement unit 72 outputs the measured value of the charge to the arithmetic and control unit 60.

[0027] The arithmetic and control unit 60 controls at least one of the rotation speed and the tilt angle of the charging tube 20. Hereinafter, an example of the process performed by the arithmetic and control unit 60 will be described.

[0028] First, the arithmetic and control unit 60 (calculation unit) according to the present embodiment calculates the specific charge of the object based on the measured value of the weight of the object output from the weight measurement unit 71 and the measured value of the charge of the object output from the charge measurement unit 72.

[0029] Next, the arithmetic and control unit 60 (arithmetic unit) calculates at least one of the rotation speed and the tilt angle of the charging tube 20 based on the calculated specific charge. For example, the relationship between the specific charge (average specific charge) and the tilt angle of the charging tube as shown in FIG. 3 may be obtained in advance, and a database showing the relationship may be stored in the arithmetic and control unit 60. In this case, the arithmetic and control unit 60 may calculate the tilt angle of the charging tube 20 based on the database. Similarly, the relationship between the specific charge (average specific charge) and the rotation speed of the charging tube 20 may be obtained in advance, and a database showing the relationship may be stored in the arithmetic and control unit 60. In this case, the arithmetic and control unit 60 may calculate the rotation speed of the charging tube 20 based on the database. Also, the relationship between the specific charge and the tilt angle, and the relationship between the specific charge and the rotation speed may be obtained for each type of object. Then, the arithmetic and control unit 60 may perform the above calculation according to the type of object input to the charging tube 20.

[0030] As shown in FIG. 3, for the tilt angle of the charging lamp 20, there may be a saturation tilt angle θs at which the specific charge (average specific charge) of the object saturates with respect to a change in which the tilt angle of the charging lamp 20 decreases (in other words, a decrease in the tilt angle of the charging lamp 20). That is, when the tilt angle of the charging lamp 20 is decreased (when the tilt angle of the charging lamp 20 is reduced), the specific charge may hardly increase when a certain tilt angle is reached. This tilt angle is the saturation tilt angle θs. When such a saturation tilt angle θs exists, the arithmetic and control unit 60 (saturation tilt angle acquisition unit) may acquire the saturation tilt angle θs. Further, the arithmetic and control unit 60 may calculate the tilt angle of the charging lamp 20 in consideration of the acquired saturation tilt angle θs. For example, when the tilt angle of the charging lamp 20 is the saturation tilt angle θs, the specific charge of the object can be increased while suppressing a decrease in the processing speed of the electrostatic separation device 1.

[0031] Then, based on the result of the above calculation, the arithmetic and control unit 60 (control unit) adjusts (controls) at least one of the rotation speed and the tilt angle of the charging lamp 20.

[0032] Note that the measurement units 71 and 72 and the arithmetic and control unit 60 may repeatedly measure the weight and charge of the object and calculate the specific charge a plurality of times at predetermined time intervals. In this case, the arithmetic and control unit 60 may detect a variation from the previous value of the specific charge. In other words, the arithmetic and control unit 60 may detect the variation when the specific charge calculated at the nth time (n is a natural number) varies from the previous value, that is, the specific charge calculated at the (n - 1)th time. Then, when the specific charge varies compared to the previous value, the arithmetic and control unit 60 may adjust at least one of the rotation speed and the tilt angle of the charging lamp 20. Specifically, when the specific charge decreases from the previous value, the arithmetic and control unit 60 may decrease the tilt angle of the charging lamp 20. Further, when the specific charge increases from the previous value, the arithmetic and control unit 60 may increase the tilt angle of the charging lamp 20.

[0033] Note that the functions of the calculation / control unit 60 (calculation unit, arithmetic unit, control unit, and saturation inclination angle acquisition unit) provided in the electrostatic separation device 1 may be realized by a CPU (Central Processing Unit) executing a program. Alternatively, it is also possible to realize the functions of the calculation / control unit 60 using hardware (including circuitry) such as an LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), or GPU (Graphics Processing Unit). Or, it is also possible to realize the functions of the calculation / control unit 60 through the cooperation of software and hardware. Also, the functions of the calculation unit, arithmetic unit, control unit, and saturation inclination angle acquisition unit may be realized by the same hardware as each other, or may be realized by separate hardware.

[0034] Hereinafter, the electrostatic separation method according to the embodiment will be described with reference to FIG. 4.

[0035] As shown in FIG. 4, the electrostatic separation method according to this embodiment includes a charging step ST1, a calculation step ST2, an arithmetic step ST3, and an adjustment step ST4.

[0036] First, the charging step ST1 is performed. In the charging step ST1, the material to be separated is put into the charging cylinder 20. This putting-in is performed, for example, by the input unit 10. As a result, a plurality of types of objects included in the material to be separated pass through the charging cylinder 20 (charging space I) and are charged. At this time, the rotation speed and inclination angle of the charging cylinder 20 are, for example, set to predetermined initial values.

[0037] Next, a calculation step ST2 is performed. In the calculation step ST2, the charge amount (electric charge) and weight of a plurality of types of objects charged in the charging step ST1 are measured. The measurement is performed by, for example, the measurement units 71 and 72. Then, based on the measured values of the charge amount and the weight, the specific charge of the object is calculated. The calculation is performed by, for example, the arithmetic and control unit 60.

[0038] Next, an arithmetic step ST3 is performed. In the arithmetic step ST3, based on the specific charge calculated in the calculation step ST2, at least one of the rotation speed and the tilt angle of the charging cylinder 20 is calculated. The calculation is performed by, for example, the arithmetic and control unit 60. In the calculation, as described above, the previously obtained relationships between the specific charge and the tilt angle of the charging cylinder 20 and between the specific charge and the rotation speed of the charging cylinder 20 may be used. Also, a calculation considering the saturation tilt angle θs may be performed.

[0039] Next, an adjustment step ST4 is performed. In the adjustment step ST4, based on the calculation result in the arithmetic step ST3, at least one of the rotation speed and the tilt angle of the charging cylinder 20 is adjusted. The adjustment is performed by, for example, the arithmetic and control unit 60. The charging step ST1 to the adjustment step ST4 may be repeated a plurality of times as necessary. In the adjustment step ST4, as described above, when the specific charge varies compared to the previous value, at least one of the rotation speed and the tilt angle of the charging cylinder 20 may be adjusted. Specifically, when the specific charge decreases from the previous value, the tilt angle of the charging cylinder 20 may be decreased. Also, when the specific charge increases from the previous value, the tilt angle of the charging cylinder 20 may be increased.

[0040] As described above, the electrostatic separation method according to the present embodiment includes a charging step ST1 of charging a plurality of types of objects included in the material to be separated by passing them through the charging tube 20, a calculation step ST2 of measuring the charge amount and weight of the plurality of types of objects charged in the charging step ST1 and calculating the specific charge, a calculation step ST3 of calculating at least one of the rotation speed and the inclination angle of the charging tube 20 based on the specific charge calculated in the calculation step ST2, and an adjustment step ST4 of adjusting at least one of the rotation speed and the inclination angle of the charging tube 20 based on the calculation result in the calculation step ST3. Further, the electrostatic separation apparatus 1 according to the present embodiment includes a charging tube 20 that charges a plurality of types of objects included in the material to be separated, a calculation unit (calculation / control unit 60) that calculates the specific charge based on the measured values of the charge amount and weight of the plurality of types of objects charged by the charging tube 20, a calculation unit (calculation / control unit 60) that calculates at least one of the rotation speed and the inclination angle of the charging tube 20 based on the specific charge calculated by the calculation unit, and a control unit (calculation / control unit 60) that adjusts at least one of the rotation speed and the inclination angle of the charging tube 20 based on the calculation result by the calculation unit.

[0041] With this configuration, even when the state of the material to be separated fluctuates, it is possible to appropriately adjust the charging conditions (the rotation speed and the inclination angle of the charging tube 20). Thereby, for example, the occurrence of insufficient charging can be suppressed. Further, when the charging time is excessive, the charging time can be shortened to improve the processing speed.

[0042] Further, the charging step ST1, the calculation step ST2, the calculation step ST3, and the adjustment step ST4 may be repeated a plurality of times. In the adjustment step ST4, when the specific charge decreases from the previous value, the inclination angle of the charging tube 20 may be decreased, and when the specific charge increases from the previous value, the inclination angle of the charging tube 20 may be increased. According to this configuration, when the state of the material to be separated fluctuates, the charging tube 20 can be adjusted more appropriately.

[0043] Further, a saturation tilt angle at which the specific charge saturates with respect to a change in which the tilt angle of the flashlight decreases may be obtained. According to this configuration, it becomes easier to achieve both an improvement in the charge amount of an object and an improvement in the processing speed.

[0044] As described above, the embodiments have been described. However, the present disclosure is not limited to the above-described embodiments, and can be freely changed without departing from the gist of the present disclosure.

[0045] Each configuration included in the electrostatic separation device 1 described above has a computer system inside. Then, a program for realizing the functions of each configuration included in the electrostatic separation device 1 described above is recorded on a computer-readable recording medium, and the program recorded on this recording medium is read into the computer system and executed, whereby the processing in each configuration included in the electrostatic separation device 1 described above may be performed. Here, "reading and executing the program recorded on the recording medium into the computer system" includes installing the program in the computer system. The "computer system" referred to here is assumed to include hardware such as an OS and peripheral devices.

[0046] Further, the "computer system" may include a plurality of computer devices connected via a network including a communication line such as the Internet or a WAN, LAN, dedicated line, or the like. The "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, a CD-ROM, or the like, or a storage device such as a hard disk incorporated in the computer system. Thus, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

[0047] In addition, the recording medium also includes an internal or external recording medium provided so as to be accessible from a distribution server for distributing the program. Note that the program may be divided into a plurality of parts, and may be configured to be combined by each component included in the electrostatic separation device 1 after being downloaded at different timings. Also, the distribution servers that distribute each of the divided programs may be different. Furthermore, the "computer-readable recording medium" includes those that hold a program for a certain period of time, such as a volatile memory (RAM) inside a computer system that becomes a server or a client when a program is transmitted via a network. Also, the above program may be for realizing a part of the functions described above. Furthermore, it may be a so-called difference file (difference program) that can realize the functions described above in combination with a program already recorded in the computer system.

Explanation of Signs

[0048] 1…Electrostatic separation device 20…Charging lamp 60…Calculation / control unit (calculation unit, arithmetic unit, control unit, saturation inclination angle acquisition unit)

Claims

1. A charging step of charging a plurality of types of objects included in a material to be sorted by passing them through a charging lamp; A calculating step of measuring the charge amount and weight of the plurality of types of objects charged in the charging step and calculating a specific charge; An arithmetic step of calculating at least one of the rotation speed and the tilt angle of the charging lamp based on the specific charge calculated in the calculating step; An adjusting step of adjusting at least one of the rotation speed and the tilt angle of the charging lamp based on the calculation result in the arithmetic step, and having: An electrostatic separation method.

2. Repeating the charging step, the calculating step, the arithmetic step, and the adjusting step a plurality of times, In the adjusting step, when the specific charge decreases from the previous value, the tilt angle of the charging lamp is decreased, and when the specific charge increases from the previous value, the tilt angle of the charging lamp is increased, The electrostatic separation method according to Claim 1.

3. Obtaining a saturation tilt angle at which the specific charge saturates with respect to a change in which the tilt angle of the charging lamp decreases, The electrostatic separation method according to Claim 1 or 2.

4. A charging lamp for charging a plurality of types of objects included in a material to be sorted; A calculation unit that calculates a specific charge based on measured values of the charge amount and weight of the plurality of types of objects charged by the charging lamp; An arithmetic unit that calculates at least one of the rotation speed and the tilt angle of the charging lamp based on the specific charge calculated by the calculation unit; A control unit that adjusts at least one of the rotation speed and the tilt angle of the charging lamp based on the calculation result by the arithmetic unit, and comprising: An electrostatic separation device.

5. When the specific charge decreases from the previous value, the control unit decreases the tilt angle of the charging lamp, When the specific charge increases from the previous value, the control unit increases the tilt angle of the charging lamp, The electrostatic separation device according to Claim 4.

6. Further comprising a saturation tilt angle acquisition unit that acquires a saturation tilt angle at which the specific charge saturates with respect to a change in which the tilt angle of the charging lamp decreases, The electrostatic separation device according to Claim 4 or 5.

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