Control method, control device, program and sorting system for mixed plastic sorting line

Abstract

A technology for sorting recycled plastics under optimal sorting conditions is disclosed. A control method for a mixed plastic sorting system (100) containing a mixture of multiple types of plastic fragments includes the steps of: a composition calculator (190) communicating with a sorting line (110) managed by an operator receives information indicating the operating status of each device constituting the sorting line (S172); calculating the arrival time of the mixed plastics input into the sorting line to each device based on the required time, first status information, and second status information; estimating the composition ratio of each plastic fragment contained in the mixed plastic input into each device based on the composition ratio obtained before input into the sorting line and the calculated arrival time; and transmitting sorting conditions corresponding to the estimated composition ratio to each device (S180).

Description

Technical Field

[0001] The present disclosure relates to the sorting of plastics, and more particularly to the optimization of techniques for sorting mixed plastics.

Background Art

[0002] Conventional plastic sorting methods employ wet gravity separation that utilizes the fact that different types of plastics have different specific gravities. More specifically, wet gravity separation is used to separate polypropylene (PP) plastic pieces with a specific gravity of 1.0 or less, acrylonitrile butadiene styrene (ABS) plastic pieces, polystyrene (PS) plastic pieces, and PP plastic pieces with glass fiber (PP with a higher specific gravity due to the addition of glass fiber, etc.) with a specific gravity of 1.0 to 1.1, and heavy specific gravity plastic pieces with a specific gravity of 1.1 or more. When the PP plastic pieces excluding the selected PP plastic pieces with glass fiber are washed and foreign substances are removed, recycled PP can be obtained.

[0003] In the case of ABS plastic pieces, PS plastic pieces, and PP plastic pieces with glass fiber having little difference in specific gravity, primary electrostatic separation is performed using the property that the charging sequence varies depending on the type of plastic. The mixture of PS plastic pieces and PP plastic pieces with glass fiber that are negatively charged and the ABS plastic pieces that are positively charged are separately recovered. Among these, for the group of mixed plastic pieces of PS plastic pieces and PP plastic pieces with glass fiber, secondary electrostatic separation different from the primary electrostatic separation is further performed, and the PS plastic pieces that are positively charged and the PP plastic pieces with glass fiber that are negatively charged are sorted and recovered.

[0004] The composition ratio of mixed plastic fragments in recycled plastics fluctuates depending on the season and the time of day. The sorting conditions of wet gravity separators or electrostatic separators are set based on the composition ratio. Therefore, conventional wet gravity separators or electrostatic separators have the problem that if the composition ratio of mixed plastic fragments fluctuates, the sorting accuracy of the plastic fragments decreases and the recovery rate decreases.

[0005] Regarding sorting conditions, Japanese Patent Publication No. 5889449 (Patent Document 1) discloses a technique that includes a step for identifying the type of plastic piece in the sorting process, and sets the sorting conditions of an electrostatic separator based on the composition ratio of the plastic piece group determined by this step. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 5889449 [Overview of the project] [Problems that the invention aims to solve]

[0007] The technology disclosed in Japanese Patent No. 5889449 involves analyzing the types of plastic fragments by sampling recycled plastic before it enters the sorting process in order to optimize sorting conditions. However, this method may reduce the sorting accuracy of the plastic fragments because the sorting equipment cannot be operated under optimal conditions while the composition of the plastic flowing through the sorting line is being analyzed. Furthermore, while recycled plastic is sorted through multiple sorting processes, analysis is required to optimize the sorting conditions for each process.

[0008] This disclosure is made in view of the above, and one objective, in a certain respect, is to provide a technology for sorting recycled plastics under optimal sorting conditions at all times. [Means for solving the problem]

[0009] According to one embodiment, a method for controlling a sorting line for mixed plastics containing multiple types of plastic pieces is provided. This control method includes the steps of: accessing the composition ratios of multiple types of plastics obtained by pre-analyzing the mixed plastic before it is introduced into the sorting line; accessing a pre-measured time required for the mixed plastic to pass through a device provided at each of the multiple processes constituting the sorting line; accessing first state information representing the operating state of the device acquired when the required time was measured; receiving second state information representing the respective operating state from each device; calculating the arrival time for the mixed plastic introduced into the sorting line to reach each device based on the required time, the first state information, and the second state information; estimating the composition ratio of each plastic piece contained in the mixed plastic introduced into each device based on the composition ratios obtained before it was introduced into the sorting line and the calculated arrival time; and transmitting sorting conditions corresponding to the estimated composition ratios to each device.

[0010] In another embodiment, a control device for a sorting line of mixed plastics containing multiple types of plastic pieces is provided. This control device comprises communication means for communicating with the sorting line, a memory, and a processor connected to the memory. The memory stores the composition ratio of multiple types of plastics obtained by pre-analyzing the mixed plastic before it is introduced into the sorting line, the time required as the time required for the mixed plastic to pass through the equipment provided at each of the multiple processes constituting the sorting line, and first state information representing the operating state of the equipment acquired when the time required was measured. The communication means receives second state information representing the operating state of each equipment. Based on the time required, the first state information, and the second state information, the processor calculates the time it takes for the mixed plastic introduced into the sorting line to reach each equipment, estimates the composition ratio of each plastic piece contained in the mixed plastic to be introduced into each equipment based on the composition ratio obtained before introduction into the sorting line and the calculated time required, and transmits sorting conditions corresponding to the estimated composition ratio to each equipment.

[0011] In another embodiment, a program is provided for controlling a sorting line for mixed plastics containing multiple types of plastic pieces. The program causes a computer to perform the following steps: access the composition ratios of multiple types of plastics obtained by pre-analyzing the mixed plastic before it is introduced into the sorting line; access the time required, which is pre-measured as the time it takes for the mixed plastic to pass through the equipment provided at each of the multiple processes constituting the sorting line; access first state information representing the operating state of the equipment, which is obtained when the time required is measured; receive second state information representing the operating state of each equipment, respectively; calculate the time it takes for the mixed plastic introduced into the sorting line to reach each equipment based on the time required, the first state information, and the second state information; estimate the composition ratio of each plastic piece contained in the mixed plastic introduced into each equipment based on the composition ratio obtained before it was introduced into the sorting line and the calculated time required; and transmit sorting conditions corresponding to the estimated composition ratios to each equipment.

[0012] In yet another embodiment, a sorting system for mixed plastics containing multiple types of plastic pieces is provided. This sorting system comprises a sorting line for sorting the mixed plastics and a control device for the sorting line. The control device comprises communication means for communicating with the sorting line, a memory, and a processor connected to the memory. The memory stores the composition ratio of multiple types of plastics obtained by pre-analyzing the mixed plastics before they are fed into the sorting line, the time required for the mixed plastics to pass through the devices provided in each of the multiple processes constituting the sorting line, which has been measured in advance, and first state information representing the operating state of the device acquired when the time required was measured. The communication means receives second state information representing the respective operating state from each device. The processor calculates the time it takes for the mixed plastics fed into the sorting line to reach each device based on the required time, the first state information, and the second state information. Based on the composition ratio obtained before feeding into the sorting line and the calculated arrival time, it estimates the composition ratio of each plastic piece contained in the mixed plastics fed into each device, and transmits sorting conditions corresponding to the estimated composition ratio to each device.

[0013] According to one embodiment, recycled plastics can always be sorted under optimal sorting conditions.

[0014] The above and other objects, features, aspects and advantages of this invention will become apparent from the following detailed description relating to this invention, which will be understood in conjunction with the accompanying drawings. [Brief explanation of the drawing]

[0015] [Figure 1] This figure illustrates an overview of the configuration of a sorting system 100 according to one embodiment. [Figure 2] This is a block diagram showing the hardware configuration of composition calculator 190. [Figure 3] This figure shows examples of the composition ratio and input amount (weight) of recycled plastics to be fed into the sorting system 100 according to this embodiment. [Figure 4] It is a schematic diagram showing the plastic composition ratio at an arbitrary position in the plastic sorting line 110 according to this embodiment. [Figure 5] It is a diagram showing the time-series change in the number of identification plastic pieces input into the plastic sorting line 110 according to this embodiment. [Figure 6] It is a flowchart showing an example of a procedure for obtaining the time taken for a plastic piece to pass through each device. [Figure 7] It is a diagram showing an outline of a method for obtaining the time until mixed plastic pieces are input into each device in the plastic sorting line 110 according to this embodiment. [Figure 8] It is a flowchart showing an example of another procedure for obtaining the time taken for a plastic piece to pass through each device. [Figure 9] It is a schematic diagram showing the plastic composition ratio (%) at an arbitrary position in the plastic sorting line according to this embodiment. [Figure 10] It is a diagram showing the time-series change in the number of identification plastic pieces input into the sorting line 110 according to this embodiment. [Figure 11] It is a diagram showing an outline of a method for obtaining the time and its variation until mixed plastic pieces are input into each device in the sorting line 110 according to this embodiment. [Figure 12] It is a diagram showing a state where a plurality of sorting lines 110-1, 110-2 ··· 110-n are communicably connected to the composition computer 190 via the network 1200.

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described while referring to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0017] Embodiment 1. Referring to FIGS. 1 to 8, a method for sorting plastics according to Embodiment 1 will be described. FIG. 1 is a diagram illustrating an overview of the configuration of a sorting system 100 according to an embodiment. The sorting system 100 includes a sorting line 110 and a composition calculator 190. The sorting line 110 and the composition calculator 190 are communicatively connected to each other.

[0018] [Sorting line] The sorting line 110 includes a flexible container (hereinafter referred to as "flexible container") 115, a charging tank 120, a charging feeder 125, a conveyor 130, a buffer tank 135, a wet specific gravity sorting device 140, a dryer 150, a first-stage electrostatic sorting device 155, and a second-stage electrostatic sorting device 160. [[ID=X]] [[ID=X]]

[0019] [[ID=X]] According to an embodiment, when mixed plastic pieces are charged from the flexible container 115 into the charging tank 120, the mixed plastic pieces are sent to the conveyor 130 by the charging feeder 125. The conveyor 130 charges the mixed plastic pieces into the buffer tank 135. The mixed plastic pieces charged into the buffer tank 135 are charged into the wet specific gravity sorting device 140 at a predetermined speed. [[ID=X]] [[ID=X]]

[0020] [[ID=X]] The wet specific gravity sorting device performs a wet specific gravity sorting process that utilizes the fact that the specific gravity varies depending on the type of plastic. More specifically, the wet specific gravity sorting device sorts plastic pieces with a specific gravity of 1.0 or less, plastic pieces with a specific gravity of 1.0 to 1. <11>, and plastic pieces with a specific gravity of 1.1 or more, and recovers each plastic piece. In a certain aspect, the plastic pieces with a specific gravity of 1.0 or less may include PP plastic pieces. The plastic pieces with a specific gravity of 1.0 to 1.1 may include ABS plastic pieces, PS plastic pieces, and PP plastic pieces containing glass fibers. The plastic pieces with a specific gravity of 1.1 or more may include heavy specific gravity plastic pieces. [[ID=X]] [[ID=X]]

[0021] [[ID=X]] Each collected plastic piece is placed into a dryer 150. If a dryer 150 is assigned to each plastic piece, each dryer 150 dries the plastic piece that is placed inside. If only one dryer 150 is used, each plastic piece is dried sequentially.

[0022] ABS plastic pieces, PS plastic pieces, and glass fiber-reinforced PP plastic pieces, which have almost no difference in specific gravity, are fed into the first-stage electrostatic separator 155. The first-stage electrostatic separator 155 performs a first-stage electrostatic separation process that utilizes the property that different types of plastics have different charge sequences, separating and recovering a mixture of negatively charged PS plastic pieces and glass fiber-reinforced PP plastic pieces from positively charged ABS plastic pieces. The mixture of PS plastic pieces and glass fiber-reinforced PP plastic pieces is then fed into the second-stage electrostatic separator 160.

[0023] The second-stage electrostatic separator 160, as part of the second-stage electrostatic separator process, separates the positively charged PS plastic pieces from the mixture of PS plastic pieces and glass fiber-reinforced PP plastic pieces, and recovers each type of plastic piece.

[0024] The composition calculator 190 is implemented, for example, by a computer having a well-known configuration. The composition calculator 190 maintains the relationship between the operating status of each device constituting the sorting line 110 (i.e., the conveyor 130, buffer tank 135, wet specific gravity separator 140, dryer 150, first-stage electrostatic separator 155, and second-stage electrostatic separator 160) and the movement speed of the plastic pieces and the amount moved per unit time. Information representing the operating status is transmitted from each device to the composition calculator 190 at predetermined timings. The method by which the composition calculator 190 acquires this relationship will be described later.

[0025] The composition calculator 190 maintains optimal sorting conditions corresponding to the composition ratio of the plastic fragment groups fed into the wet specific gravity separator 140, the first-stage electrostatic separator 155, and the second-stage electrostatic separator 160, respectively. These optimal sorting conditions are obtained by conducting multiple experiments in advance, varying the composition ratio of the plastic fragment groups fed into the wet specific gravity separator 140, the first-stage electrostatic separator 155, and the second-stage electrostatic separator 160, as well as the sorting conditions. In other words, the sorting condition that yields the best sorting accuracy among the multiple sorting conditions is selected by the user of the sorting system 100 as the optimal sorting condition.

[0026] In the plastic sorting process, signals corresponding to the composition analysis results of each mixed plastic piece group in each flexible container 115 placed in the input tank 120, signals representing the total weight of the plastic pieces in each flexible container 115, and signals representing the operating status of each device constituting the sorting line 110 are sequentially input to the composition calculator 190 (steps S170, S172). The timing of sending the signals representing the operating status of each device to the composition calculator 190 may be periodic, or it may be when a change in the operating status of each device is detected.

[0027] The composition calculator 190 uses the input signals to sequentially calculate the composition of the plastic piece group fed into each device. The composition calculator 190 uses the composition obtained from the calculation to determine the optimal sorting conditions for each device. The composition calculator 190 sequentially sends signals to each device constituting the sorting line 110 to optimize the operating state of that device (step S180). Upon receiving the signals, each device sequentially changes its operating state to the optimal conditions according to the composition of the plastic piece group. In this embodiment, the operating state of the device includes, for example, the conveying speed of the plastic pieces in the conveyor 130 and the operation and stopping of the wet specific gravity separator 140, but other elements may also be adopted as the operating state of the device. For example, the temperature and drying time in the dryer 150 may also be adopted as the operating state of the device.

[0028] In this embodiment, the mixed plastic pieces are primarily crushed pieces obtained by crushing recyclable plastics from collected waste home appliances. However, the mixed plastic pieces are not limited to those exemplified herein, and the technical concepts disclosed herein can also be applied to uncrushed plastic pieces or newly manufactured plastic pieces.

[0029] [Composition calculator] The specific configuration of the composition calculator 190 will be explained with reference to Figure 2. Figure 2 is a block diagram showing the hardware configuration of the composition calculator 190.

[0030] The composition calculator 190 includes, as its main components, a CPU (Central Processing Unit) 1 for executing programs, a mouse 2 and keyboard 3 for receiving input instructions from the user of the composition calculator 190 (for example, an operator of the sorting line 110), RAM 4 for volatilely storing data generated by the execution of programs by the CPU 1 or data input via the mouse 2 or keyboard 3, a hard disk 5 for non-volatilely storing data, an optical disc drive 6, a communication interface (I / F) 7, and a monitor 8. Each component is connected to the others by a data bus. A CD-ROM (Compact Disc - Read Only Memory) 9 or other optical disc is mounted in the optical disc drive 6.

[0031] The processing in the composition calculator 190 is realized by each piece of hardware and software executed by the CPU 1. Such software may be pre-stored on the hard disk 5. Alternatively, the software may be stored on a CD-ROM 9 or other recording medium and distributed as a computer program product. Or, the software may be provided as a downloadable application program by an information provider connected to the so-called Internet. Such software is read from the recording medium by an optical disc drive 6 or other reading device, or downloaded via a communication interface 7, and then temporarily stored on the hard disk 5. The CPU 1 reads the software from the hard disk 5 and stores it in RAM 4 in the form of an executable program. The CPU 1 then executes the program.

[0032] The components constituting the composition calculator 190 shown in Figure 2 are common. Therefore, one of the essential parts of the technical concept relating to this disclosure can be said to be the software stored in the RAM 4, hard disk 5, CD-ROM 9, or other recording media, or software that can be downloaded via a network. The recording media may include non-temporary, computer-readable data recording media. The operation of each hardware component of the composition calculator 190 is well known, so a detailed explanation will not be repeated.

[0033] The recording medium is not limited to CD-ROMs, FDs (Flexible Disks), and hard disks, but may also include SSDs (Solid State Drives), magnetic tapes, optical discs (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc)), IC (Integrated Circuit) cards (including memory cards), optical cards, mask ROMs, EPROMs (Electronically Programmable Read-Only Memory), EEPROMs (Electronically Erasable Programmable Read-Only Memory), flash ROMs, and other semiconductor memory media that permanently store programs.

[0034] The term "program" as used here includes not only programs that can be directly executed by CPU1, but also programs in source code format, compressed programs, encrypted programs, and so on.

[0035] Alternatively, instead of CPU1, a parallel-programmable processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination of these may be used.

[0036] [Composition ratio of recycled plastics] Refer to Figure 3 to explain the differences between lots of recycled plastic. Figure 3 is a diagram showing examples of the composition ratio and input amount (weight) of recycled plastic fed into the sorting system 100 according to this embodiment.

[0037] The mixed plastics fed into the sorting line 110 are transported to the factory in large flexible containers 115 (1 flexible container = 1 lot), and after being put into the input tank 120, they are sent to the sorting processes by the wet specific gravity separator 140, the first-stage electrostatic separator 155, and the second-stage electrostatic separator 160. It is known that the composition of the mixed plastics within the same flexible container 115 is almost uniform. The composition of the mixed plastics constantly fluctuates depending on the season and the supplier. As shown in Figure 2 as an example, there may be lots with different compositions of various plastic pieces, such as Lot A, Lot B, or Lot C.

[0038] [Composition ratio in the sorting line] The changes in the plastic composition ratio will be explained with reference to Figure 4. Figure 4 is a schematic diagram showing the plastic composition ratio at an arbitrary position in the plastic sorting line 110 according to this embodiment. This schematic diagram shows the plastic composition ratio when lots A, B, and C of the mixed plastic shown in Figure 3 are sequentially fed into the sorting line 110.

[0039] State (A) conceptually represents the ratio (%) of the number of plastic pieces in lots A, B, and C before they are fed into sorting line 110. The ratio of the number of plastic pieces in each lot remains almost constant over time.

[0040] State (B) conceptually represents the percentage of plastic fragments before they are fed into the wet gravity separator 140. Since no sorting of plastic fragments has been performed, the percentage of plastic fragments in each lot is the same as the percentage in state (A).

[0041] State (C) conceptually represents the ratio (%) of the number of each plastic piece before sorting by the first-stage electrostatic separator 155 (i.e., the state after PP and heavy specific gravity plastics have been removed as a result of sorting by the wet specific gravity separator 140).

[0042] State (D) conceptually represents the ratio (%) of the number of each type of plastic piece before sorting by the second-stage electrostatic separator 160 (i.e., the state after PS has been removed as a result of sorting by the first-stage electrostatic separator 155).

[0043] In the example shown in Figure 4, inter-lot mixing of the mixed plastic pieces flowing through each sorting step of the sorting line 110 can be ignored. In such cases, if the input quantity of each lot and the amount and time that the mixed plastic pieces pass through each device constituting the sorting line 110 can be determined, the composition calculator 190 can estimate the composition of the mixed plastic piece group at any given time from the composition of the mixed plastic piece group that was determined in advance before being input into the sorting line 110.

[0044] [Calculation of time to pass through the device] Referring to Figures 5 and 6, a method for determining the time it takes for a plastic piece to pass through each device constituting the sorting line 110 will be described. Figure 5 is a diagram showing the time-series change in the number of identification plastic pieces fed into the plastic sorting line 110 according to this embodiment. Figure 6 is a flowchart showing an example of the procedure for determining the time it takes for a plastic piece to pass through each device.

[0045] In a given scenario, approximately 100 identification plastic pieces are fed into the sorting line 110 at once. Identification plastic pieces are plastic pieces whose location can be identified by visual inspection. Identification plastic pieces have, for example, a color or shape that distinguishes them from other plastic pieces. Alternatively, plastic pieces containing fluorescent paint may be used as identification plastic pieces. In this case, the identification plastic pieces will change color when exposed to ultraviolet light, allowing their location to be identified.

[0046] Graph (A) in Figure 5 conceptually represents the distribution of the number of identification plastic fragments detected before being fed into the sorting line 110. Here, time t(1) indicates the timing when the largest number of identification plastic fragments are detected.

[0047] Graph (B) conceptually represents the distribution of the number of identification plastic pieces detected after time t(1) before being fed into the wet specific gravity separator 140. Here, time t(2) indicates the timing when the largest number of identification plastic pieces are detected.

[0048] Graph (C) conceptually represents the distribution of the number of identification plastic pieces detected after time t(2) and before sorting by the first-stage electrostatic separator 155. Here, time t(3) indicates the timing when the largest number of identification plastic pieces are detected.

[0049] Graph (D) conceptually represents the distribution of the number of identification plastic pieces detected after time t(3) and before sorting by the second-stage electrostatic separator 160. Here, time t(4) indicates the timing when the largest number of identification plastic pieces are detected.

[0050] The operator monitors these positions in the sorting line 110 (step S610) and records the operating status of each device constituting the sorting line 110 (step S620). The operator can then determine the relationship between the time it takes for the mixed plastic pieces introduced into the sorting line 110 to pass through each device constituting the sorting line 110 and the operating status of each device (step S630).

[0051] Furthermore, since the statistical variability can be determined from the number of identification plastic pieces in the sorting line 110, the number of identification plastic pieces fed into the sorting line 110 is not necessarily limited to 100. In this embodiment, since plastic pieces from different lots do not mix together in the sorting line, the time it takes for the identification plastic pieces to pass through each process does not vary, as shown in Figure 5.

[0052] Referring to Figures 7 and 8, other methods for determining the time it takes for a plastic piece to pass through each device constituting the sorting line 110 will be described. Figure 7 is a schematic diagram showing a method for determining the time it takes for a mixed plastic piece to be fed into each device in the plastic sorting line 110 according to this embodiment. Figure 8 is a flowchart showing an example of another procedure for determining the time it takes for a plastic piece to pass through each device.

[0053] As shown in Figure 7, state (A) conceptually represents the ratio (%) of the number of plastic pieces in lots A, B, and C before they are fed into the sorting line 110. Even as time progresses, the ratio of the number of plastic pieces in each lot remains almost constant.

[0054] State (B) conceptually represents the percentage of plastic fragments before they are fed into the wet gravity separator 140. Since no sorting of plastic fragments has been performed, the percentage of plastic fragments in each lot is the same as the percentage in state (A).

[0055] State (C) conceptually represents the ratio (%) of the number of each plastic piece before sorting by the first-stage electrostatic separator 155 (i.e., the state after PP and heavy specific gravity plastics have been removed as a result of sorting by the wet specific gravity separator 140).

[0056] State (D) conceptually represents the ratio (%) of the number of each type of plastic piece before sorting by the second-stage electrostatic separator 160 (i.e., the state after PS has been removed as a result of sorting by the first-stage electrostatic separator 155).

[0057] Before introducing the mixed plastic pieces into the sorting line 110, the operator pre-analyzes the composition of the mixed plastic pieces (step S810). As shown in state (A) of Figure 7, the proportions of each type of plastic piece in the mixed plastic pieces are constant.

[0058] Subsequently, the operator records the operating status of each device in the sorting line 110 (step S820) and periodically takes plastic pieces from each sorting process to analyze the composition of the plastic pieces (step S830). In this embodiment, the operator can arbitrarily determine the timing of the periodic sampling, for example, every 5 minutes or every 10 minutes. Alternatively, the timing can be determined according to the processing speed of each device constituting the sorting line 110.

[0059] As shown in state (B) of Figure 7, before sorting by the wet specific gravity separator 140, the ratio of each plastic remains unchanged from the ratio in state (A). When sorting by the wet specific gravity separator 140 is performed, PP and heavy specific gravity plastics are removed, so the ratio of the remaining plastic pieces becomes the ratio of ABS, glass fiber reinforced PP, and PS (state (C)). Furthermore, when sorting by the first-stage electrostatic separator 155 is performed, ABS is removed, so the ratio of the remaining plastic pieces becomes the ratio of glass fiber reinforced PP and PS (state (D)).

[0060] The operator can determine the time it takes for the mixed plastic pieces to pass through each device by comparing the time-dependent changes in the composition of the mixed plastic pieces during the sorting process with the composition of the mixed plastic pieces before they are introduced into the sorting line 110 (step S840) (step S850). This allows the operator to determine the relationship between the time it takes for the mixed plastic pieces introduced into the sorting line to pass through each device constituting the sorting line and the operating state of each device.

[0061] The operator of the sorting line 110 inputs into the composition calculator 190 the relationship between the time required for the mixed plastic pieces to pass through each sorting device and the operating status of the device, which was determined in advance using the method described above.

[0062] The CPU1 of the composition calculator 190 uses the aforementioned relationship and data on the operating status of each device constituting the sorting line 110 (conveyor 130, buffer tank 135, wet specific gravity separator 140, dryer 150, first-stage electrostatic separator 155, and second-stage electrostatic separator 160) to estimate the time required for the mixed plastic pieces introduced into the sorting line 110 to pass through each device. The composition of the mixed plastic pieces introduced into the sorting line 110 is known from analysis performed in advance by the operator. Therefore, the CPU1 can calculate and estimate the composition of the mixed plastic pieces introduced into each sorting device at any given time.

[0063] The composition calculator 190 sequentially transmits the optimal sorting conditions to each device based on the composition estimation results from the CPU 1. When each device receives these sorting conditions, it changes its own sorting conditions to the received conditions.

[0064] Here, we will describe an electrostatic separation device that follows other aspects, specifically one that is configured with a control function provided by a composition calculator 190. This electrostatic separation device has a pair of electrodes through which mixed plastic pieces pass, and by adjusting the distance between the electrodes according to the composition of the mixed plastic piece group, high-precision separation can be performed.

[0065] In contrast, the composition calculator 190 according to this embodiment calculates the composition of the mixed plastic pieces to be fed into each device of the sorting line 110 at any given time, based on the analysis results of the composition of the mixed plastic pieces fed into the sorting line 110, data on the operating status of each device constituting the sorting line 110, and the relationship between the time required for the mixed plastic pieces fed into the sorting line 110 to pass through each device and the operating status of the device, which has been determined in advance. From the estimated composition of the mixed plastic pieces, the composition calculator 190 calculates the optimal distance between electrodes in the first-stage electrostatic separator 155 and the second-stage electrostatic separator 160, respectively. The composition calculator 190 transmits the said distance between electrodes to the first-stage electrostatic separator 155 and the second-stage electrostatic separator 160, respectively. The first-stage electrostatic separator 155 and the second-stage electrostatic separator 160 adjust the distance between electrodes to the optimal value based on the information received from the composition calculator 190.

[0066] The above-described embodiment explains the case where the composition within each lot is constant (for example, lot A, lot B, lot C). If the composition within a single lot varies, the plastic pieces can be sampled just before being fed into the input feeder 125 shown in Figure 1, their composition analyzed, and the result (signal) input into the composition calculator 190.

[0067] In other words, a single lot where compositional variations are expected can be treated as a collection of mini-lots corresponding to each composition. By analyzing the composition of the plastic pieces contained in each mini-lot and deriving sorting conditions that improve analytical accuracy, the operator can determine the optimal sorting conditions even when the composition varies within a single lot.

[0068] Embodiment 2. Embodiment 2 will be described with reference to Figures 9 to 11. Embodiment 1 showed a case where plastic pieces from a previously introduced lot and plastic pieces from a later introduced lot did not mix. In some situations, the plastic pieces from each lot may mix with each other. Therefore, Embodiment 2 will describe a case where the plastic pieces from each lot mix with each other. The hardware configuration of the sorting system according to this embodiment is the same as the hardware configuration of the sorting system 100 according to Embodiment 1. Therefore, the following description will refer to the hardware configuration of the sorting system 100.

[0069] Figure 9 is a schematic diagram showing the plastic composition ratio (%) at an arbitrary position in a plastic sorting line according to this embodiment. State (A) shows the case where lots A, B, and C, shown with reference to Figure 6 in Embodiment 1, are sequentially fed into the sorting line 110, but in this embodiment, plastic pieces from different lots are mixed together in the sorting line 110.

[0070] At a certain stage, as individual plastic pieces in the mixed plastic pass through the input tank 120, input feeder 125, conveyor 130, buffer tank 135, wet specific gravity separator 140, dryer 150, first-stage electrostatic separator 155, and second-stage electrostatic separator 160, mixing occurs between the plastics flowing ahead and the plastics flowing behind. The degree of mixing increases as the pieces pass through the devices. Therefore, the composition ratio of the plastic pieces at each stage of the sorting process can change from a discontinuous composition ratio to a gradual composition ratio.

[0071] For example, state (B) represents the composition ratio of the mixed plastic pieces before they are fed into the wet gravity separator 140. State (C) represents the composition ratio of the mixed plastic pieces before they are fed into the first-stage electrostatic separator 155. State (D) represents the composition ratio of the mixed plastic pieces before they are fed into the second-stage electrostatic separator 160.

[0072] In such cases, in order to estimate the composition ratio of the group of plastic pieces flowing into the sorting line 110 at any given time, it is necessary to know in advance not only the time it takes for the plastic pieces to pass through each device that makes up the sorting line 110, but also the variability in that time.

[0073] Therefore, referring to Figure 10, we will explain the time it takes for a plastic piece to pass through each device constituting the sorting line 110, and a method for determining the variation in that time.

[0074] Figure 10 shows the time-series change in the number of identification plastic pieces fed into a sorting line 110 according to this embodiment. The operator feeds approximately 100 identification plastic pieces, as described in Embodiment 1, into the sorting line 110. The operator records the elapsed time since feeding the pieces into the sorting line 110, the number of identification plastic pieces flowing through each device constituting the sorting line 110, and the operating status of each device. The operator monitors the position of each identification plastic piece in the sorting line 110 and records the operating status of each device constituting the sorting line 110. The operator can determine the relationship between the average time required for the mixed plastic pieces fed into the sorting line 110 to pass through each device constituting the sorting line 110, the variance of the required time, and the operating status of each device.

[0075] In this embodiment, since mixed plastic pieces from different lots are mixed together in the sorting line 110, the time required for identification plastic pieces to be discharged from each device varies, as shown in Figure 10. However, since the statistical variation can be determined from the number of identification plastic pieces in the sorting line 110, the number of identification plastic pieces fed into the sorting line 110 is not necessarily limited to 100.

[0076] Referring to Figure 11, another method for determining the time it takes to pass through each device will be described. Figure 11 is a schematic diagram showing a method for determining the time it takes for mixed plastic pieces to be fed into each device and the variation in that time in a sorting line 110 according to this embodiment.

[0077] Before introducing the mixed plastic pieces into the sorting line 110, the operator pre-analyzes the composition of the mixed plastic pieces and stores the composition ratio (also called the "initial composition ratio") based on the analysis results in the composition calculator 190.

[0078] The operator records the operating status of each device in the sorting line 110, periodically takes an appropriate amount of plastic pieces from each device, analyzes the composition of the taken plastic pieces, and derives a composition ratio based on the analysis results. There is no particular limit to the number of plastic pieces taken; for example, an amount that fits into a container capable of holding about 100 plastic pieces is taken. The operator stores the derived composition ratio in the composition calculator 190.

[0079] The CPU 1 of the composition calculator 190 compares the change over time in the composition ratio of each type of plastic fragment group contained in the mixed plastic fed into each sorting process consisting of the wet specific gravity separator 140, the first-stage electrostatic separator 155, and the second-stage electrostatic separator 160, with the composition ratio of the mixed plastic fragment group before it is fed into the sorting line 110 (initial composition ratio). This allows the CPU 1 to determine the average time required and the variability of the required time for the mixed plastic fragments to pass through the wet specific gravity separator 140, the first-stage electrostatic separator 155, and the second-stage electrostatic separator 160. From this, the CPU 1 can determine the relationship between the average time required for the mixed plastic fed into the sorting line 110 to pass through each device constituting the sorting line 110, the variance of the required time, and the operating state of each device.

[0080] The operator inputs the relationship between the average time required for the mixed plastic to pass through each device, the variance of the required time, and the operating status of the device, as determined by the method described above, into the composition calculator 190. For example, the operator associates the average time, the variance, and the operating status with each other and stores the associated data (also called "relational data") in the hard disk 5. The form in which the relational data is stored is, for example, a table format, but the form in which the relational data is stored is not particularly limited.

[0081] The CPU1 of the composition calculator 190 uses this relationship and data representing the operating status of each device constituting the sorting line 110 (conveyor 130, buffer tank 135, wet specific gravity separator 140, dryer 150, first-stage electrostatic separator 155, and second-stage electrostatic separator 160) to estimate the time required for the mixed plastic introduced into the sorting line 110 to pass through each device, and the degree of mixing of the mixed plastics contained in different lots. The composition ratio of the mixed plastic introduced into the sorting line 110 is determined in advance by analysis before it is introduced into the sorting line 110. Therefore, the CPU1 can estimate the composition ratio of the mixed plastic introduced into each sorting device, namely the wet specific gravity separator 140, the first-stage electrostatic separator 155, and the second-stage electrostatic separator 160, respectively.

[0082] CPU1 transmits the optimal sorting conditions corresponding to this estimation result to each sorting device. The sorting conditions include the magnitude of the voltage of the two electrode tubes used in the first-stage electrostatic sorting device 155 and the second-stage electrostatic sorting device 160, and the position of the partition plate (not shown) provided in the collection box that receives positively or negatively charged plastic pieces.

[0083] Furthermore, the throughput (the amount of plastic pieces that flows through a device per unit time while it is operating, or the amount of plastic pieces that a device can sort per unit time (processing volume)) of each device constituting the sorting line 110 is not necessarily the same for all of them. The processing volume of plastic pieces in the sorting line 110 is limited by the slower devices, so the faster devices will have to repeatedly pause.

[0084] Furthermore, even if the flow rate of plastic pieces passing through the input feeder 125 remains constant, as sorting progresses (in subsequent processes) and the types of plastic pieces constituting the mixed plastic flowing through decrease, the amount of the (decreased) mixed plastic will change according to the fluctuations in the composition ratio of the mixed plastic when it passed through the input feeder 125 (backward). In addition, any of the devices may temporarily stop due to malfunction, blockage, or other problems. In this case, temporary stoppages may occur irregularly.

[0085] Therefore, the impact of a temporary shutdown of the equipment in the sorting line 110 according to this embodiment will be handled as follows. Two methods for determining the time it takes to pass through each device were illustrated in Embodiment 1 and Embodiment 2.

[0086] However, if any of the devices temporarily stops, the mixed plastic processed in the stopped device will be fed to the next device (the next process) with a delay equal to the time the device was stopped. Therefore, the operator or CPU1 creates data for the temporarily stopped device, interpreting it as if the plastic pieces moved in a shorter time (i.e., the actual operating time) equal to the time the device was stopped, and stores this data in the hard disk 5 of the composition calculator 190.

[0087] In sorting mixed plastics, when determining the composition ratio of the plastic pieces fed into each sorting device, namely the wet specific gravity separator 140, the first-stage electrostatic separator 155, and the second-stage electrostatic separator 160, the operator or CPU 1 may use the information on the time the sorting device was temporarily stopped, from the operational status information sent from each sorting device, to correct for the delay caused by that temporary stoppage.

[0088] Furthermore, the degree of mixing of the plastic pieces in Embodiment 2 is not affected by the time the system is temporarily stopped.

[0089] Embodiment 3. Embodiment 3 will be described with reference to Figure 12. The composition calculator according to this embodiment differs from the composition calculators 190 according to the previously described embodiments in that it can determine the optimal sorting conditions for each of the multiple sorting lines 110 according to the operating state of the sorting line 110.

[0090] Figure 12 shows a configuration in which multiple sorting lines 110-1, 110-2, ..., 110-n are connected to a composition computer 190 via a network 1200. The network 1200 may be either the internet or an intranet.

[0091] The hardware configuration of the composition calculator according to this embodiment is the same as the hardware configuration of the composition calculator 190 described above. Therefore, the description of this hardware configuration will not be repeated.

[0092] In a given situation, if multiple sorting lines 110-1, 110-2...110-n are used by the same operator, the composition calculator 190 is managed and operated by that operator.

[0093] In other scenarios, multiple sorting lines 110-1, 110-2, ..., 110-n may belong to separate operators. In this case, the composition calculator 190 is managed and operated by the manufacturer of the sorting line. Each user of the multiple sorting lines 110-1, 110-2, ..., 110-n may be a separate operator from the manufacturer. In this case, the administrator of the composition calculator 190 (for example, the manufacturer) may provide each user of the multiple sorting lines 110-1, 110-2, ..., 110-n with a service to optimize the operation of the sorting line.

[0094] In this case, for example, the composition computer 190 may operate as a server device as follows: First, the composition computer 190 receives login authentication information, including a pre-assigned user ID and password, from one of the sorting lines 110-1, 110-2...110-n. If the login authentication information is genuine, the composition computer 190 accepts a service request from the sorting line that sent the login authentication information.

[0095] The composition calculator 190 requests the sorting line to transmit information on the composition ratio of the mixed plastics to be introduced, information representing the operating status of each device constituting the sorting line, and other various types of information as described in the above-described embodiment. When the sorting line receives this request from the composition calculator 190, it transmits the requested information to the composition calculator 190.

[0096] The composition calculator 190 determines the optimal sorting conditions according to the operating state of the sorting line based on various information received from the sorting line, and transmits the determined sorting conditions to the sorting line. The sorting line can adjust the conditions of each sorting device (for example, the voltage value applied between electrodes, the position of the partition plate provided between multiple collection boxes that receive charged plastic pieces) based on these sorting conditions.

[0097] According to this embodiment, users of the sorting line can receive an optimization service for sorting conditions provided by the composition calculator 190.

[0098] As described above, according to the disclosed embodiment, the composition ratio of the mixed plastic pieces passing through any point in each sorting process corresponding to each device constituting the sorting line 110 is constantly known. Therefore, in order to optimize the sorting conditions of each device, it is not necessary to analyze the composition of the mixed plastic pieces being fed into each device; the composition only needs to be analyzed before feeding into the sorting process. This not only significantly reduces the number of analyses, but also suppresses the impact on sorting accuracy due to the discrepancy between the time when the mixed plastic is sampled for analysis and the time when the optimal conditions are set based on the analysis results.

[0099] Some of the technical features disclosed above can be summarized as follows: (Configuration Example 1) In a certain scenario, the hard disk 5 stores the composition ratios of multiple types of plastics obtained by pre-analyzing the mixed plastic before it is fed into the sorting line 110, the required time measured in advance as the time it takes for the mixed plastic to pass through the equipment provided in each of the multiple processes constituting the sorting line 110, and first state information representing the operating state of the equipment acquired when the required time was measured. The CPU 1 reads this information from the hard disk 5. The CPU 1 receives second state information representing the operating state of each equipment from each equipment (step S172). Based on the required time, the first state information, and the second state information, the CPU 1 calculates the arrival time of the mixed plastic fed into the sorting line 110 to each equipment. Based on the composition ratios obtained before feeding into the sorting line 110 and the calculated arrival time, the CPU 1 estimates the composition ratio of each plastic piece contained in the mixed plastic fed into each equipment. The CPU 1 transmits sorting conditions corresponding to the estimated composition ratios to each equipment (step S180).

[0100] (Configuration Example 2) In another scenario, the hard disk 5 stores the composition ratios of multiple types of plastics obtained by pre-analyzing the mixed plastic before it is fed into the sorting line 110, the average value and variability of the time required, which is the time it takes for the mixed plastic to pass through the equipment provided in each of the multiple processes constituting the sorting line 110, and first state information representing the operating state of the equipment acquired when the time required was measured. The CPU 1 reads this information from the hard disk 5. The CPU 1 receives second state information representing the operating state of each equipment from each equipment. Based on the average value and variability of the time required, the first state information, and the second state information, the CPU 1 calculates the arrival time of the mixed plastic fed into the sorting line 110 to each equipment. Based on the composition ratios obtained before feeding into the sorting line 110 and the calculated arrival time, the CPU 1 estimates the composition ratio of each plastic piece contained in the mixed plastic fed into each equipment. The CPU 1 transmits sorting conditions corresponding to the estimated composition ratios to each equipment.

[0101] (Configuration Example 3) In other aspects, in addition to Configuration Example 1 or Configuration Example 2, the hard disk 5 further stores the downtime, which is the time when any of the devices provided in each of the multiple processes constituting the sorting line 110 were temporarily stopped. The CPU 1 reads this information from the hard disk 5. The CPU 1 calculates the time obtained by subtracting the downtime from the previously measured required time as the effective arrival time. Based on the composition ratio obtained before input and the effective arrival time, the CPU 1 estimates the composition ratio of each plastic piece contained in the mixed plastic to be input into each device.

[0102] (Configuration Example 4) In other aspects, in addition to Configuration Example 1 or Configuration Example 2, the pre-measured required time includes the time required for a mixture of plastics, which contains multiple types of plastics, and a plastic piece that can be identified as a different type of plastic piece, to pass through the device.

[0103] (Configuration Example 5) In other aspects, in addition to Configuration Example 1 or Configuration Example 2, the multiple devices include an electrostatic separator. The sorting conditions include conditions that define the operation of the electrostatic separator.

[0104] (Configuration Example 6) In other aspects, in addition to Configuration Example 1 or Configuration Example 2, the electrostatic sorting device includes multiple electrodes. The sorting conditions include the distance between each electrode.

[0105] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of equivalents of the claims are intended. [Explanation of symbols]

[0106] 1 CPU, 2 Mouse, 3 Keyboard, 4 RAM, 5 Hard disk, 6 Optical disc drive, 7 Communication interface, 8 Monitor, 9 CD-ROM, 100 Sorting system, 110 Sorting line, 115 Flexible container, 120 Input tank, 125 Input feeder, 130 Conveyor, 135 Buffer tank, 140 Wet specific gravity separator, 150 Dryer, 155 First-stage electrostatic separator, 160 Second-stage electrostatic separator, 190 Composition calculator, 1200 Network.

Claims

1. A method for controlling a sorting line for mixed plastics in which multiple types of plastic pieces are mixed, comprising the steps of: accessing the composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics prior to input to the sorting line; A step of accessing a time required for the mixed plastic to pass through a device provided in each of a plurality of processes constituting the sorting line, the time being measured in advance; accessing first status information representative of an operational status of the device obtained at the time the time duration was measured; receiving second status information from each of the devices, the second status information being indicative of a respective operational status; Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the required time, the first status information, and the second status information; A step of estimating the composition ratio of each of the plastic pieces contained in the mixed plastics input to each of the devices based on the composition ratio obtained before input to the sorting line and the calculated arrival time; and transmitting, to each of the devices, a selection condition according to the estimated composition ratio.

2. A method for controlling a sorting line for mixed plastics in which multiple types of plastic pieces are mixed, comprising the steps of: accessing the composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics prior to input to the sorting line; A step of accessing an average value and a variance of a required time that is measured in advance as a time required for the mixed plastic to pass through a device provided in each of a plurality of processes that constitute the sorting line; accessing first status information representative of an operational status of the device obtained at the time the time duration was measured; receiving second status information from each of the devices, the second status information being indicative of a respective operational status; Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the average value and variation of the required time, the first status information, and the second status information; A step of estimating the composition ratio of each of the plastic pieces contained in the mixed plastics input to each of the devices based on the composition ratio obtained before input to the sorting line and the calculated arrival time; and transmitting, to each of the devices, a selection condition according to the estimated composition ratio.

3. The method further includes a step of accessing a stop time previously acquired as a time during which any of the devices provided in each of the plurality of processes constituting the sorting line is temporarily stopped, The step of calculating the arrival time includes a step of calculating a time obtained by subtracting the stop time from the previously measured required time as a substantial arrival time, The control method described in claim 1 or 2, wherein the estimating step includes a step of estimating the composition ratio of each of the plastic pieces contained in the mixed plastic fed into each of the devices based on the composition ratio obtained before the feeding and the actual arrival time.

4. The control method described in claim 1 or 2, wherein the pre-measured required time includes a pre-measured required time for mixed plastics containing plastic pieces identifiable as plastic pieces different from the multiple types of plastic pieces and the multiple types of plastic pieces to pass through the device.

5. Each of the devices provided in the plurality of steps includes an electrostatic separation device, The control method according to claim 1 or 2, wherein the sorting conditions include conditions that define an operation of the electrostatic sorting device.

6. The electrostatic separation device includes a plurality of electrodes; The control method according to claim 5 , wherein the selection conditions include a distance between the electrodes.

7. A control device for a sorting line for mixed plastics in which multiple types of plastic pieces are mixed, communication means for communicating with the sorting line; Memory, a processor coupled to the memory, The memory includes: A composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics before inputting them into the sorting line; A required time measured in advance as a time required for the mixed plastic to pass through a device provided in each of a plurality of processes constituting the sorting line; and first status information representing an operating status of the device acquired when the required time was measured; the communication means receives second status information from each of the devices, the second status information representing an operation status of each of the devices; The processor, Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the required time, the first status information, and the second status information; Based on the composition ratio obtained before input into the sorting line and the calculated arrival time, estimate the composition ratio of each of the plastic pieces contained in the mixed plastic input into each of the devices; A control device transmits, to each of the devices, a selection condition corresponding to the estimated composition ratio.

8. A control device for a sorting line for mixed plastics in which multiple types of plastic pieces are mixed, communication means for communicating with the sorting line; Memory, a processor coupled to the memory, The memory includes: A composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics before inputting them into the sorting line; The average value and variation of the time required for the mixed plastic to pass through the devices provided in each of the multiple processes constituting the sorting line, which are measured in advance; and first status information representing an operating status of the device acquired when the required time was measured; the communication means receives second status information from each of the devices, the second status information representing an operation status of each of the devices; The processor, Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the average value and the variation of the required time, the first status information, and the second status information; Based on the composition ratio obtained before input into the sorting line and the calculated arrival time, estimate the composition ratio of each of the plastic pieces contained in the mixed plastic input into each of the devices; A control device transmits, to each of the devices, a selection condition corresponding to the estimated composition ratio.

9. the memory further stores a stop time acquired in advance as a time during which any of the devices provided in each of the plurality of processes constituting the sorting line is temporarily stopped, calculating the arrival time includes calculating a time obtained by subtracting the stop time from the previously measured required time as a substantial arrival time; The control device described in claim 7 or 8, wherein the estimating step includes estimating the composition ratio of each of the plastic pieces contained in the mixed plastic fed into each of the devices based on the composition ratio obtained before the feeding and the actual arrival time.

10. A control device as described in claim 7 or 8, wherein the pre-measured required time includes a pre-measured required time for mixed plastics containing plastic pieces identifiable as plastic pieces different from the multiple types of plastic pieces and the multiple types of plastic pieces to pass through the device.

11. Each of the devices provided in the plurality of steps includes an electrostatic separation device, The control device according to claim 7 or 8, wherein the sorting conditions include conditions that define an operation of the electrostatic sorting device.

12. The electrostatic separation device includes a plurality of electrodes; The control device according to claim 11 , wherein the selection conditions include a distance between each of the electrodes.

13. A program for controlling a sorting line for mixed plastics in which a plurality of types of plastic pieces are mixed, the program being configured to: accessing the composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics prior to input to the sorting line; A step of accessing a time required for the mixed plastic to pass through a device provided in each of a plurality of processes constituting the sorting line, the time being measured in advance; accessing first status information representative of an operational status of the device obtained at the time the time duration was measured; receiving second status information from each of the devices, the second status information being indicative of a respective operational status; Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the required time, the first status information, and the second status information; A step of estimating the composition ratio of each of the plastic pieces contained in the mixed plastics input to each of the devices based on the composition ratio obtained before input to the sorting line and the calculated arrival time; and transmitting, to each of the devices, selection conditions according to the estimated composition ratio.

14. A program for controlling a sorting line for mixed plastics in which a plurality of types of plastic pieces are mixed, the program being configured to: accessing the composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics prior to input to the sorting line; A step of accessing an average value and a variance of a required time that is measured in advance as a time required for the mixed plastic to pass through a device provided in each of a plurality of processes that constitute the sorting line; accessing first status information representative of an operational status of the device obtained at the time the time duration was measured; receiving second status information from each of the devices, the second status information being indicative of a respective operational status; Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the average value and variation of the required time, the first status information, and the second status information; A step of estimating the composition ratio of each of the plastic pieces contained in the mixed plastics input to each of the devices based on the composition ratio obtained before input to the sorting line and the calculated arrival time; and transmitting, to each of the devices, selection conditions according to the estimated composition ratio.

15. The program includes: The step of accessing a stop time previously acquired as a time during which any of the devices provided in each of the plurality of processes constituting the sorting line was temporarily stopped, The step of calculating the arrival time includes a step of calculating a time obtained by subtracting the stop time from the previously measured required time as a substantial arrival time, The program described in claim 13 or 14, wherein the estimating step includes a step of estimating the composition ratio of each of the plastic pieces contained in the mixed plastic fed into each of the devices based on the composition ratio obtained before the feeding and the actual arrival time.

16. The program described in claim 13 or 14, wherein the pre-measured required time includes a pre-measured required time for mixed plastic containing plastic pieces identifiable as plastic pieces different from the multiple types of plastic pieces and the multiple types of plastic pieces to pass through the device.

17. A system for sorting mixed plastics containing multiple types of plastic pieces, comprising: A sorting line for sorting the mixed plastics; A control device for the sorting line, The control device includes: communication means for communicating with the sorting line; Memory, a processor coupled to the memory, The memory includes: A composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics before inputting them into the sorting line; A required time measured in advance as a time required for the mixed plastic to pass through a device provided in each of a plurality of processes constituting the sorting line; and first status information representing an operating status of the device acquired when the required time was measured; the communication means receives second status information from each of the devices, the second status information representing an operation status of each of the devices; The processor, Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the required time, the first status information, and the second status information; Based on the composition ratio obtained before input into the sorting line and the calculated arrival time, estimate the composition ratio of each of the plastic pieces contained in the mixed plastic input into each of the devices; A sorting system that transmits sorting conditions according to the estimated composition ratio to each of the devices.

18. A system for sorting mixed plastics containing multiple types of plastic pieces, comprising: A sorting line for sorting the mixed plastics; A control device for the sorting line, The control device includes: communication means for communicating with the sorting line; Memory, a processor coupled to the memory, The memory includes: A composition ratio of the plurality of types of plastics obtained by pre-analyzing the mixed plastics before inputting them into the sorting line; The average value and variation of the time required for the mixed plastic to pass through the devices provided in each of the multiple processes constituting the sorting line, which are measured in advance; and first status information representing an operating status of the device acquired when the required time was measured; the communication means receives second status information from each of the devices, the second status information representing an operation status of each of the devices; The processor, Calculating the arrival time of the mixed plastics input into the sorting line to each of the devices based on the average value and the variation of the required time, the first status information, and the second status information; Based on the composition ratio obtained before input into the sorting line and the calculated arrival time, estimate the composition ratio of each of the plastic pieces contained in the mixed plastic input into each of the devices; A sorting system that transmits sorting conditions according to the estimated composition ratio to each of the devices.

19. the memory further stores a stop time acquired in advance as a time during which any of the devices provided in each of the plurality of processes constituting the sorting line is temporarily stopped, calculating the arrival time includes calculating a time obtained by subtracting the stop time from the previously measured required time as a substantial arrival time; The sorting system described in claim 17 or 18, wherein the estimating step includes estimating the composition ratio of each of the plastic pieces contained in the mixed plastic input into each of the devices based on the composition ratio obtained before the input and the actual arrival time.

20. The sorting system described in claim 17 or 18, wherein the pre-measured required time includes a pre-measured required time for mixed plastics containing plastic pieces identifiable as plastic pieces different from the multiple types of plastic pieces and the multiple types of plastic pieces to pass through the device.

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