Method and apparatus for sorting recycled materials

Abstract

Efficiently and accurately sorts stainless steel from recycled materials. [Solution] The system includes a preliminary sorting step of removing the main metals, including iron and aluminum, from the recycled raw material to select the preliminary sorted raw material; a residual metal sorting step of determining the presence or absence of conductivity and color of the preliminary sorted raw material to separate it into non-metallic materials and residual metals; and a color sorting step of further determining the presence or absence of conductivity and color of the residual metals to separate them into stainless steel and other materials. The color sorting step includes a first color sorting step of sorting the residual metals into white metals and non-white metals, and a second color sorting step of sorting the white metals into stainless steel and other materials.

Description

Technical Field

[0001] The present invention relates to a sorting method and a sorting device for sorting stainless steel from recycled raw materials containing valuable metals (such as Cu, Au, Ag, Pt, Pd, etc.) used in copper smelters and the like.

[0002] Since stainless steel is also mixed in the recycled raw materials, when processing the recycled raw materials in a copper smelter or the like, copper is mixed into the slag due to the Cr content in the stainless steel, which has been a factor in increasing the copper loss rate. For this reason, various technologies for sorting and removing stainless steel from recycled raw materials have been developed.

[0003] In Patent Document 1, as a recycling method for waste OA equipment, three-stage magnetic separation is performed. Specifically, first magnetic separation is performed to crush waste containing metal and sort it into iron filings and other filings, second magnetic separation is performed to sort aluminum-based metal from the other filings with a magnetic force stronger than that of the first magnetic separation, and third magnetic separation is performed to sort stainless steel-based metal from the remaining filings with a magnetic force stronger than that of the second magnetic separation. Although stainless steel-based metal is sorted in the third stage, according to Patent Document 1, in the second and third magnetic separations, further manual sorting is required thereafter.

[0004] In Patent Document 2, as a sorting method for sorting stainless steel from crushed waste, high-magnetic-force sorting of stainless steel is performed after a roller press. However, raw materials that cannot be roller-pressed may be mixed in the recycled raw materials, and it is not always applicable to all recycled raw materials.

[0005] In Patent Document 3, mixed metals are separated into metals and nonmetals by a metal-nonmetal separation process, then eddy currents are generated and separated into falling metals containing stainless steel and copper wire, and flying metals containing copper, aluminum and zinc, by the repulsive force with a magnet, and the falling metals are further separated into red metals and non-red metals containing stainless steel using a color sensor. However, with sorting using only a color sensor, it is difficult to separate stainless steel from other non-red metals. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2001-58138 [Patent Document 2] Japanese Patent Publication No. 2000-33287 [Patent Document 3] Japanese Patent Publication No. 2012-139609 [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention has been made in view of these circumstances, and aims to efficiently and accurately separate stainless steel from recycled raw materials. [Means for solving the problem]

[0008] The present invention provides a method for sorting recycled raw materials, comprising: a preliminary sorting step of removing main metals including iron and aluminum from the recycled raw materials to sort the preliminary sorted raw materials; a residual metal sorting step of determining the presence or absence of conductivity and color of the preliminary sorted raw materials to separate them into non-metallic materials and residual metals having a metallic color; and a color sorting step of further determining the presence or absence of conductivity and color of the residual metals to sort them into stainless steel and others.

[0009] Since the main metals, including iron and aluminum, are removed in advance, subsequent sorting can be carried out efficiently. Then, the pre-sorted raw materials, from which these main metals, including iron and aluminum, have been removed, are first sorted into non-metallic materials and residual metals using sorting based on conductivity and color. Furthermore, the residual metals are sorted into stainless steel and other materials. By combining sorting by conductivity and sorting by color, the target materials can be accurately sorted.

[0010] In the method for sorting recycled raw materials of the present invention, the color sorting step comprises a first color sorting step of sorting the remaining metals into white metals and non-white metals, and a second color sorting step of sorting the white metals into stainless steels and others.

[0011] The remaining metals are first separated into white metals and non-white metals, and then stainless steel is selected from the white metals. By progressively narrowing down the selection target, stainless steel can be selected with high precision in the end.

[0012] In the method for sorting recycled materials of the present invention, the preliminary sorting step comprises a magnetic sorting step of sorting the recycled materials into magnetic and non-magnetic materials by magnetic force, and an eddy current sorting step of sorting the non-magnetic materials into aluminum scrap and the preliminary sorted materials which are non-aluminum materials by eddy current sorting.

[0013] Since iron and aluminum are separated using magnetic and eddy current separation, the process can be carried out relatively inexpensively, and the separation accuracy is stable.

[0014] In the method for sorting recycled materials of the present invention, after the color sorting step, the stainless steel sorted in the color sorting step is used as the sorting target instead of the non-magnetic material, and the process from the eddy current sorting step to the color sorting step is repeated.

[0015] By repeating the processes from eddy current sorting to color sorting, the sorting accuracy of stainless steel can be further improved, thereby increasing its value as a commercial product when it is manufactured.

[0016] In the method for sorting recycled materials of the present invention, it is preferable to have a crushing step of crushing the recycled materials before the preliminary sorting step.

[0017] In the method for sorting recycled materials of the present invention, it is preferable to have a sieving step between the crushing step and the preliminary sorting step, in which the crushed recycled materials are sorted into recycled materials of a predetermined size or larger using a sieve. By sorting the materials into predetermined sizes beforehand, the accuracy of subsequent sorting can be improved.

[0018] The present invention provides a sorting apparatus for recycled raw materials, comprising: a residual metal sorter that sorts the sorted raw materials, which have been pre-sorted from recycled raw materials to include iron and aluminum, by determining the presence or absence of conductivity and metallic color to separate them into non-metals and residual metals; and a color sorter that sorts the residual metals further by determining the presence or absence of conductivity and white color to separate them into white metals and non-white metals while sorting stainless steel. The residual metal sorting machine is equipped with an electromagnetic sensor for detecting the presence or absence of conductivity in the sorted raw material and a near-infrared sensor for detecting the metallic color. The color sorter includes an electromagnetic sensor for detecting the presence or absence of conductivity in the remaining metals and a color sensor for detecting their color.

[0019] In the recycling material sorting apparatus of the present invention, the color sorter preferably comprises a first color sorter that sorts the white metals into white metals and non-white metals, and a second color sorter that sorts the white metals into stainless steel and other materials. [Effects of the Invention]

[0020] According to the present invention, by combining sorting by conductivity and color, stainless steel can be efficiently and accurately sorted from recycled raw materials.

Brief Description of the Drawings

[0021] [Figure 1] This is a flowchart showing the method for sorting recycled raw materials in an embodiment of the present invention in the order of steps. [Figure 2] This is a schematic configuration diagram of a sorting device for recycled raw materials in an embodiment. [Figure 3] This is a schematic diagram of the main part showing an example of an eddy current separator. [Figure 4] This is a schematic diagram of the main part showing an example of a residual metal separator. [Figure 5] This is a schematic diagram of the main part showing an example of a first color sorter. [Figure 6] This is a diagram showing the change in the contained weight by material for each sorting step in the examples.

Modes for Carrying Out the Invention

[0022] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The recycled raw materials handled in this embodiment are wastes such as home appliances like televisions and refrigerators, electronic devices such as computers and mobile phones, automotive electrical equipment, and electronic components, wiring, substrates, etc. contained therein. This method for sorting recycled raw materials includes a crushing step, a preliminary sorting step, a residual metals sorting step, and a color sorting step, as shown in the flowchart of FIG. 1. FIG. 2 shows the schematic configuration of the sorting device used in this sorting method. Hereinafter, it will be described in the order of steps.

[0023] [Crushing Step] In the crushing step, known crushers such as crushers and mills can be used, and the recycled raw materials are crushed by this crusher to an appropriate size, for example, a particle size (diameter of the maximum dimension part) of 10 mm or more and 50 mm or less.

[0024] [Preliminary Sorting Step] The preliminary sorting step includes a screening step, a magnetic separation step, and an eddy current separation step.

[0025] (sieving process) In the sieving process, the crushed material from the crushing process is sorted to a predetermined size using a sieving machine. For example, a sieve with a mesh size of 10 mm is used in the sieving machine, separating undersized particles (less than 10 mm) from the bottom of the sieve and oversized particles (10 mm or larger) from the top. Vibration of the sieve is recommended. Oversized particles are sent to the next magnetic separation process. Undersized particles mainly consist of finely crushed substrates and can be used as raw materials for copper refining.

[0026] (Magnetic separation process) In the magnetic separation process, known magnetic separators such as drum-type magnetic separators and conveyor-type suspended magnetic separators can be used. The excess material (objects to be separated in the magnetic separation process) that was separated in the sieving process is separated into magnetically attracted material and non-magnetic material. In this magnetic separation process, iron scrap is separated as magnetically attracted material, and materials other than iron scrap are separated as non-magnetic material. The non-magnetic material is sent to the next eddy current separation process, and the magnetically attracted material is used as raw material for copper refining.

[0027] (Eddy current sorting process) In the eddy current separation process, for example, a magnetic rotor type eddy current separator as shown in Figure 3 is used. In this eddy current separator 1, the pulley 3 at the end of the belt conveyor 2 that transports the magnetically attached material (the object to be separated in the eddy current separation process) separated in the magnetic separation process is formed into a cavity, and a magnetic rotor 4 is installed inside it. Because this magnetic rotor 4 is installed eccentrically with respect to the pulley 3, it is close to the end of the belt conveyor 2, and the rotation of the magnetic rotor 4 generates an alternating magnetic field near the end of the belt conveyor 2.

[0028] Then, when the object to be sorted 5, which has been transported by the belt conveyor 2, enters the alternating magnetic field near the end of the belt conveyor 2, if the object to be sorted 5 is a conductor, eddy currents are generated on its surface. These eddy currents create a magnetic field that repels the alternating magnetic field (a magnetic field with the same polarity as the alternating magnetic field), and due to this repulsive force, it bounces away from the surface of the belt conveyor 2 and falls, as shown by arrow A. On the other hand, if the object to be sorted 5 is not a conductor, it falls straight down at the end of the belt conveyor 2, as shown by arrow B, without being affected by the alternating magnetic field. These differences in falling positions separate the object to be sorted 5 into conductors and non-conductors. By adjusting the magnitude of the alternating magnetic field of the eddy current separator 1, the conductors to be sorted can be made to be mainly aluminum.

[0029] Furthermore, a separation plate 6 is provided to partition the areas between the falling objects to be sorted, preventing them from mixing. By adjusting the position of this separation plate 6, the proportion of aluminum scrap that is sorted can be adjusted. Collection containers 7 and 8 are provided at each of the falling locations.

[0030] This eddy current separation process separates the conductive aluminum scrap from the residual metals, including non-aluminum materials, that were separated in the magnetic separation process. The aluminum scrap may also contain small amounts of copper scrap. This aluminum scrap is used as a raw material for copper refining.

[0031] In this preliminary sorting process, scrap iron, scrap aluminum, etc. are removed through sorting, and the remaining metals, including non-aluminum materials with a size of 10 mm to 50 mm, are extracted as preliminary sorted raw materials and sent to the next remaining metal sorting process.

[0032] [Residual Metal Sorting Process] In the residual metal sorting process, a combined sorting machine (residual metal sorting machine) 11 using an electromagnetic sensor and a near-infrared sensor is used to distinguish residual metals (objects to be sorted in the residual metal sorting process) based on the presence or absence of conductivity and color, and separate them into non-metallic and metallic materials.

[0033] This combined sorting machine 11 sorts objects 13 by the presence or absence of conductivity using an electromagnetic sensor 12 and sorts them by color using a near-infrared sensor 14. It comprises a belt conveyor 15 for transporting residual metals sent from a preliminary sorting process, an electromagnetic sensor 12 and a near-infrared sensor 14 installed in the middle of the belt conveyor 15, an air nozzle 16 at the end of the belt conveyor 15 that blows away metals from the objects 13 based on the detection results of the electromagnetic sensor 12 and the near-infrared sensor 14, a control computer 17 that controls the air nozzle 16 based on the output of the electromagnetic sensor 12 and the near-infrared sensor 14, and collection containers 18 and 19 that divide and collect the objects to be sorted that fall from the belt conveyor 15 into metals and non-metals.

[0034] The electromagnetic sensor 12 is positioned on the underside of the belt conveyor 15. It generates a high-frequency magnetic field on the belt conveyor 15. When a conductive object 13 approaches the magnetic field, an induced current flows through the object 13 due to electromagnetic induction. This current causes a change in the impedance of the electromagnetic sensor 12 or stops its oscillation, thereby detecting the conductor. If the object 13 is not a conductor, it passes through the conveyor. Since the ultimate goal is to sort stainless steel, the electromagnetic sensors are installed slightly away from the conveyor belt, for example, 10-20 mm, to effectively sort stainless steel, which has high electrical resistance, from among all conductive materials.

[0035] Meanwhile, the near-infrared sensor 14 is installed above the belt conveyor 15 and monitors the light reflected from the sorting target objects 13 passing on the belt conveyor 15 by the light emitted from the light source 14a, and determines whether the reflected light is near-infrared (light with a wavelength of, for example, 700 nm to 2500 nm). This near-infrared indicates that the reflected light is metallic in color. In the example shown in Figure 4, the near-infrared sensor 14 is positioned to face the electromagnetic sensor 12 via a belt conveyor 15.

[0036] Then, if the object to be sorted 13 is detected as a conductor by the electromagnetic sensor 12 and as metallic in color by the near-infrared sensor 14, it is blown away by the air nozzle 16 at the end of the belt conveyor 15 as indicated by arrow C and sorted into the collection container 19. If the object to be sorted 13 is determined not to be a conductor by the electromagnetic sensor 12 and not to be metallic in color by the near-infrared sensor 14, it falls straight down at the end of the belt conveyor 15 as indicated by arrow D. In this case, if the object to be sorted 13 is determined not to be a conductor by the electromagnetic sensor 12 and not to be metallic by the near-infrared sensor 14, the object to be sorted 13 is a non-metallic material (including plastic) and is sorted into the collection container 18 from the belt conveyor 15. The sorted non-metallic materials are used as raw materials for copper smelting, while the metallic materials are sent to the next color sorting process.

[0037] [Color sorting process] The color sorting process is carried out in two stages: the first color sorting stage and the second color sorting stage.

[0038] (First color sorting process) In the first color sorting process, the metals sorted in the residual metal sorting process (objects to be sorted in the first color sorting process) are sorted into white metals and non-white metals by a combined sorter (first color sorter) 23 using an electromagnetic sensor 21 and a color sensor 22, which determines whether or not they are conductive and their color.

[0039] In the combined sorting machine 23, the electromagnetic sensor 21 is the same as the one used in the residual metal sorting machine 11 described above, but by adjusting its sensitivity, distance from the belt conveyor 24, etc., white metals including stainless steel are sorted as conductors and distinguished from non-white metals.

[0040] The color sensor 22 detects color based on the ratio of R (red), G (green), and B (blue) in the reflected light emitted from the light source 22a. It determines that the material is a white metal when all three colors—red, green, and blue—are detected as reflected light of a predetermined intensity. Furthermore, this color sensor 22 is a line sensor and also identifies the two-dimensional shape of the objects to be sorted 25, removing square objects (e.g., connectors) and round objects (e.g., batteries). In addition, to eliminate the influence of the color of the belt conveyor 24, the objects to be sorted 25 are detected at the rear end of the belt conveyor 24.

[0041] If both the electromagnetic sensor 21 and the color sensor 22 determine that the object is a non-white metal (including connectors and batteries), the object is blown down near the end of the belt conveyor 24 by the air nozzle 26, as indicated by arrow E. If the object is determined to be a white metal (not a connector or battery), it is not blown down by the air nozzle 26 and falls far away from the end of the belt conveyor 24, as indicated by arrow F. In this case, the air nozzle 26 blows the white metal into the collection container 27 located directly below the end of the belt conveyor 24, while the non-white metal that falls as if thrown from the end of the belt conveyor 24 is collected in the collection container 28. Reference numeral 29 indicates a control computer that controls the air nozzle 26 based on the outputs of the electromagnetic sensor 21 and the color sensor 22. The sorted non-white metals are used as raw materials for copper smelting, while the white metals are sent to the next second color sorting process.

[0042] Incidentally, if the eddy current separation process, which is carried out before this first color sorting process, were not performed, since aluminum is also a white metal, a large amount of aluminum would be mixed in with stainless steel among the white metals sorted in this first color sorting process, making subsequent sorting difficult. For this reason, it is important to sort and remove as much aluminum as possible using the eddy current separation process before this first color sorting process.

[0043] (Second color sorting process) The second color sorting process has the same configuration as the first color sorter, so it is not shown in the diagram, but it has a combined sorter that uses an electromagnetic sensor and a color sensor, and sorts the white metals (objects to be sorted in the second color sorting process) sorted in the first color sorting process by determining whether or not they are conductive and by their color, separating them into stainless steel and non-stainless steel.

[0044] In this second color sorting process, the electromagnetic sensor is used in the same way as in the first color sorting process, but with an adjusted distance to the electromagnetic sensor, thereby enabling the sorting of stainless steel materials from non-stainless steel materials. For example, the electromagnetic sensor distance is 16 mm in the first color sorting process and 18 mm in the second color sorting process. In this second color sorting process, objects identified as stainless steel by both the electromagnetic sensor and the color sensor are collected in a stainless steel collection container, while all other non-stainless steel materials are collected in a non-stainless steel collection container. These non-stainless steel materials are used as raw materials for copper refining.

[0045] This sorting method removes the main metals, including iron and aluminum, beforehand, allowing for more efficient subsequent sorting. The separation of iron and aluminum is carried out using proven methods such as magnetic separation and eddy current separation, making it relatively inexpensive and ensuring stable sorting accuracy. Then, the pre-sorted raw materials, from which the main metals including iron and aluminum have been removed, are first sorted into non-metallic materials and residual metals (residual metal sorting process) based on conductivity and color. Further sorting of the residual metals into stainless steel and other materials (color sorting process). By combining sorting by conductivity and sorting by color, the materials to be sorted can be accurately selected. Furthermore, in the color sorting process, the remaining metals are first separated into white metals and non-white metals (first color sorting process), and then stainless steel is selected from the white metals (second color sorting process). Because the sorting targets are narrowed down sequentially, stainless steel can be selected with high precision in the end.

[0046] In this way, stainless steel is separated through various sorting processes. The collected stainless steel may, if necessary, be subjected to the sorting processes described above, from the eddy current sorting process to the second color sorting process, again. This process may be repeated three or more times.

[0047] In this second sorting process, only materials sorted as stainless steel are handled, so even if each sorting machine is set to the same settings as the first time, the sorting accuracy can be improved. By adjusting the sensitivity of each sorting machine as needed, a more precise sorting process can be performed. As a result, the stainless steel content in the sorted stainless steel is increased, making it possible to handle it as high-grade stainless steel.

[0048] Although embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. For example, in the sorting machines shown in Figures 4 and 5, some of the objects to be sorted are blown away by an air nozzle at the end of the belt conveyor, but a guide plate-like device that distributes the objects to be sorted to the left and right on the belt conveyor may also be used. Furthermore, while the second sorting process was carried out starting from the eddy current sorting stage, it is also possible to carry it out starting from the magnetic sorting stage. [Examples]

[0049] The results of the verification experiment conducted to confirm the effects of the present invention will be explained. As recycled raw materials, we prepared materials mainly consisting of circuit boards with a high stainless steel content. From approximately 15 kg of recycled material (raw material in Figure 6) with a size of 10 mm or larger, iron scraps were separated by magnetic force using a drum-type magnetic separator with a magnetic flux density of 1000 G, causing them to fall into a separate container. Furthermore, a 3000G magnetic rotor type eddy current separator was used to separate and remove aluminum scraps from non-magnetic materials by using electromagnetic force to propel them away.

[0050] Subsequently, a combined sorting machine (EM+NIR) using electromagnetic and near-infrared sensors was used to separate metals from non-aluminum materials by blowing them with air. In this combined sorting machine, the sensitivity of the electromagnetic sensor was set to 450, with a maximum value of 1000. Next, from the sorted metals, a combined sorting machine (EM+Color) using electromagnetic sensors and a color line camera was used to blow away non-white metals with compressed air, separating the white metals.

[0051] Subsequently, non-stainless steel materials (primarily copper alloys) were blown away with compressed air from the white metal materials using a modified electromagnetic sensor and color line camera combined sorter (EM+Color), and the stainless steel materials were recovered. The electromagnetic sensor + color line camera combined sorter (EM+Color) was configured to separate all non-white metal materials in the first pass, and then in the second pass, any white metal materials where even a small amount of plating had peeled off and red (copper) or yellow (brass) could be seen were separated as non-stainless steel materials.

[0052] After each sorting stage, the weight of each material was measured, and the recovery rate and purity of the stainless steel were calculated. The results are shown in Figure 6. In Figure 6, stainless steel is abbreviated as SUS, aluminum as Al, copper plate / copper wire as Cu / Wire, and substrate as PCB.

[0053] As shown in the first (topmost) table of Figure 6, 14.56 kg of raw material containing a mixture of stainless steel, aluminum, substrate, copper, etc. was subjected to magnetic separation, eddy current separation, residual metal separation, first color separation, and second color separation. As shown in the final (bottommost) table, it was possible to separate the material into 0.47 kg of stainless steel, including 0.37 kg of pure stainless steel. In this case, the stainless steel recovery rate was 71.2% (0.37 kg / 0.52 kg as a percentage), and the purity of the stainless steel was 79.5% (0.37 kg / 0.47 kg as a percentage; the figures do not match due to differences in the number of decimal places in measurement). This shows that stainless steel can be recovered with a recovery rate of at least 65%, or even 70% or more. Furthermore, the substrate content in the recovered stainless steel could be kept to, for example, 2% or less (0% in Figure 6).

[0054] Next, the stainless steel materials sorted as described above were subjected to each sorting process again, from eddy current sorting to second color sorting. During this process, the position of the branching plate of the eddy current sorter, the position of the electromagnetic sensor in the combined sorter (EM+NIR) (first color sorter) which combines an electromagnetic sensor and a near-infrared sensor, and the setting of the color line camera in the combined sorter (EM+Color) (second color sorter) which combines an electromagnetic sensor and a color line camera were changed. Eddy current separator: The branching plate was positioned closer to the belt conveyor to facilitate the removal of conductive materials. First color sorter: The electromagnetic sensor was moved away from the conveyor belt to reduce its sensitivity, making it easier to remove non-white metals. Second color sorter: This machine analyzes images from a color line camera, recognizes the shape of the object being sorted, and is configured to remove batteries and connectors. The sorting process used two lots of recycled raw materials, and each sorting step, from eddy current sorting to secondary color sorting, was performed twice for each lot. The results are shown in Table 1.

[0055] [Table 1]

[0056] As can be seen from Table 1, re-sorting improved the stainless steel recovery rate to over 95% in all lots. By properly adjusting each sorting machine, it is believed that a stainless steel recovery rate of at least 80%, or even over 90% depending on the required specifications, can be achieved. [Explanation of Symbols]

[0057] 1. Eddy current separator 2 Belt conveyor 3 Pulley 4 Magnetic rotors 5. Items to be sorted 6 Separation plate 7,8 Collection container 11. Combined sorting machine (residual metal sorting machine) 12 Electromagnetic sensors 13. Items to be sorted 14. Near-infrared sensor 15 Belt conveyor 16 Air nozzles 17 Control computer 18,19 Collection container 21 Electromagnetic Sensors 22 Color Sensors 23. Combined sorting machine (first color sorter) 24 Belt conveyor 25 Items to be sorted 26 Air Nozzles 27,28 Collection container 29 Control computer

Claims

1. A method for sorting recycled materials, comprising: a crushing step for crushing recycled materials; a preliminary sorting step for removing main metals including iron and aluminum from the crushed recycled materials to sort pre-sorted materials; a residual metal sorting step for sorting the pre-sorted materials into non-metals and residual metals by determining the presence or absence of conductivity and color; and a color sorting step for further sorting the residual metals into stainless steels and others by determining the presence or absence of conductivity and color.

2. The method for sorting recycled raw materials according to claim 1, characterized in that the color sorting step comprises a first color sorting step for sorting the remaining metals into white metals and non-white metals, and a second color sorting step for sorting the white metals into stainless steels and others.

3. The method for sorting recycled materials according to claim 1, characterized in that the preliminary sorting step comprises a magnetic sorting step for separating the crushed recycled material into magnetic and non-magnetic materials by magnetic force, and an eddy current sorting step for separating the non-magnetic material into aluminum scrap and the preliminary sorted material which is a non-aluminum material by eddy current sorting.

4. The method for sorting recycled raw materials according to claim 3, characterized in that, after the color sorting step, the stainless steel sorted in the color sorting step is used as the sorting target in place of the remaining metals, and the process from the eddy current sorting step to the color sorting step is repeated.

5. The method for sorting recycled materials according to claim 1, characterized in that it includes a crushing step of crushing the recycled materials before the preliminary sorting step.

6. The method for sorting recycled materials according to claim 3, characterized in that, between the crushing step and the preliminary sorting step, there is a sieving step in which the crushed recycled material is sorted into recycled materials of a predetermined size or larger using a sieve.

7. The system comprises a residual metal sorting machine that sorts pre-sorted raw materials, which are obtained by pre-sorting the main metals including iron and aluminum from recycled raw materials, by determining whether they are conductive and their metallic color, thereby separating them into substrate parts and residual metals; and a color sorting machine that sorts the residual metals further by determining whether they are conductive and their white color, separating them into white metals and non-white metals, while also sorting stainless steel. The residual metal sorting machine is equipped with an electromagnetic sensor for detecting the presence or absence of conductivity in the sorted raw material and a near-infrared sensor for detecting the metallic color. The aforementioned color sorter is a sorting device for recycled materials, characterized by comprising an electromagnetic sensor for detecting the presence or absence of conductivity in the residual metals and a color sensor for detecting their color.

8. The sorting apparatus for recycled raw materials according to claim 7, characterized in that the color sorter comprises a first color sorter that sorts the white metals into white metals and non-white metals, and a second color sorter that sorts the white metals into stainless steel and other materials.

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