Permanent magnet recovery device and permanent magnet recovery method

Abstract

Provided is a permanent magnet recovery device and a permanent magnet recovery method in which, even when a resin material having a low microwave absorption rate is used as an adhesive in a permanent magnet holder, uneven heating does not occur in the permanent magnet holder when the permanent magnet is recovered by microwave heating. A permanent magnet recovery device (1) includes a heat treatment furnace (2) that houses a permanent magnet holder (5) in which a permanent magnet (8) is mounted on a laminated steel sheet (6) having an insulating film via a resin material (7), and in which a heat insulating material (10) is provided in a range in contact with the resin material (7) on both end portions of the laminated steel sheet (6) in the stacking direction; and a microwave generation device (3) that radiates microwaves into the heat treatment furnace (2). A permanent magnet recovery method includes a heat insulating material mounting step (S1) of mounting a heat insulating material (10) that transmits microwaves in a range in contact with the resin material (7) on both end portions of the permanent magnet holder (5); and a microwave heating step (S2) of heating the permanent magnet holder (5) on which the heat insulating material (10) is mounted, with a microwave heating furnace (4).

Description

Technical Field

[0001] This invention relates to a permanent magnet recycling device and a permanent magnet recycling method. Background Technology

[0002] In recent years, measures to significantly reduce waste generation through prevention, reduction, recycling, and reuse have become increasingly active. To achieve this, research and development related to the recycling of permanent magnets is underway. A technique has been devised to disassemble a magnetic circuit structure, such as the rotor of a rotating electric motor, in which permanent magnets are fixed with adhesive to a laminated steel plate to recover the permanent magnets (see, for example, Patent Document 1). In the technique of Patent Document 1, the magnetic circuit structure is heated to a high temperature using a heavy oil furnace to carbonize the adhesive and recover the permanent magnets. Furthermore, a technique has been devised to utilize microwave heating to raise the temperature of a laminated steel plate coated with an adhesive film, thereby promoting the adhesion of the adhesive film (see, for example, Patent Document 2).

[0003] [Previous Technical Documents]

[0004] (Patent Documents)

[0005] Patent Document 1: Japanese Patent Application Publication No. 2001-85223

[0006] Patent Document 2: Japanese Patent Application Publication No. 11-234972 Summary of the Invention

[0007] [The problem the invention aims to solve]

[0008] However, in technologies related to the recycling of permanent magnets, the problem to be solved is recycling without damaging the inherent properties of expensive permanent magnets. In the technology of Patent Document 1, the magnetic circuit structure is heated to a high temperature using a heavy oil furnace, thereby intentionally disabling the permanent magnets for complete recycling. Conversely, prolonged exposure of expensive permanent magnets to high temperatures causes cracks and oxidation in the extracted magnets, resulting in deteriorated properties even after remagnetization, making direct remagnetization impossible. Therefore, from a resource recycling perspective, this represents a significant loss. On the other hand, the technology of Patent Document 2 is specifically designed to firmly bond the layers of laminated steel plates. Therefore, it does not address the specific recycling target, such as permanent magnets, from the magnetic circuit structure. Consequently, it cannot be directly used for recycling purposes.

[0009] In view of the above, the applicant has proposed a permanent magnet recycling apparatus and method that can recycle permanent magnets without impairing their properties, wherein the permanent magnets are mounted on a laminated steel plate with an insulating film via a resin material (Japanese Patent Application P2021-214038). If permanent magnets can be recycled without impairing their properties, they can be reused, reducing the need to manufacture new permanent magnets and mitigating environmental impacts such as reduced carbon dioxide emissions.

[0010] In the applicant's previous proposal, for example, the rotor of a rotary electric motor was configured as a permanent magnet holder, and high-frequency absorbers were installed at least within the range of contact with resin material at both ends of the laminated steel plates in the lamination direction. The permanent magnet holder had a permanent magnet mounted on the laminated steel plates with an insulating film via resin material. When recycling the permanent magnet, if the permanent magnet holder is heated using microwaves, it can be uniformly heated along with the resin material inside the holder until the high-frequency absorbers at both ends are reached without temperature deviation. This causes the adhesive force of the resin material, which acts as a binder, to fail, making it easier to remove the permanent magnet. On the other hand, the permanent magnet portion does not heat up significantly, thus allowing recycling without damaging the properties of the permanent magnet.

[0011] The microwave absorptivity of the resin material used as a binder in a permanent magnet holder varies depending on its type. If a permanent magnet holder uses a resin material with low microwave absorptivity, only the high-frequency absorbers near the outer surface are heated, resulting in uneven internal temperature distribution and what is known as uneven heating. Therefore, the heating efficiency of the entire permanent magnet holder is low, and short-term heating is insufficient for demagnetization, necessitating a separate demagnetization step.

[0012] To address the aforementioned problems, the present invention aims to provide a permanent magnet recycling device and method that, even when using a resin material with low microwave absorption as the binder in the permanent magnet holder, prevents uneven heating within the permanent magnet holder during microwave heating for permanent magnet recycling. Furthermore, the invention aims to demagnetize the permanent magnet while simultaneously recovering it in a state that suppresses cracking and oxidation, thereby significantly reducing waste generation.

[0013] [Technical means to solve the problem]

[0014] (1) A permanent magnet recycling apparatus (e.g., permanent magnet recycling apparatus 1 described later) comprising: a heat treatment furnace (e.g., heat treatment furnace 2 described later), a permanent magnet holder (e.g., permanent magnet holder 5 described later), wherein the permanent magnet holder has a permanent magnet (e.g., permanent magnet 8 described later) mounted on a laminated steel plate (e.g., laminated steel plate 6 described later) having an insulating film via a resin material (e.g., resin material 7 described later), and a microwave-permeable heat-insulating material (e.g., heat-insulating material 10 described later) is provided at least in contact with the resin material at both ends of the laminated steel plate in the lamination direction; and a microwave generating apparatus (e.g., microwave generating apparatus 3 described later) for applying microwaves into the heat treatment furnace.

[0015] (2) According to the permanent magnet recycling device described in (1) above, the penetration depth of the insulation material is greater than the penetration depth of the resin material.

[0016] (3) According to the permanent magnet recycling device described in (2) above, the resin material is epoxy resin, the heat insulation material is alumina-based or silica-based heat insulation material, and the thickness of the heat insulation material is less than 50 mm.

[0017] (4) A method for recycling permanent magnets, comprising: an insulation material installation step (e.g., insulation material installation step S1 described later), on a permanent magnet holder (e.g., permanent magnet holder 5 described later) on a laminated steel plate (e.g., laminated steel plate 6 described later) having an insulating film, on which permanent magnets (e.g., permanent magnets 8 described later) are installed via resin material (e.g., resin material 7 described later), in a range at least in contact with the resin material at both ends of the laminated steel plate in the lamination direction; and a microwave heating step (e.g., microwave heating step S2 described later), heating the permanent magnet holder on which the insulation material was installed in the insulation material installation step using a microwave heating furnace (e.g., microwave heating furnace 4 described later).

[0018] (5) According to the permanent magnet recycling method described in (4) above, in the heat insulation material installation step, heat insulation material with a penetration depth greater than that of resin material is installed at both ends of the laminated steel plate in the lamination direction.

[0019] (6) According to the permanent magnet recycling method described in (5) above, the resin material is epoxy resin and the insulation material is an alumina-based or silica-based insulation material with a thickness of less than 50 mm.

[0020] (The effect of the invention)

[0021] In the permanent magnet recycling device of (1), heat dissipation from the end side of the laminated steel plate, which is difficult to heat with microwaves, is suppressed by a microwave-penetrating insulating material. On the other hand, this end side does not obstruct microwave penetration into the resin material, which acts as a binder. Therefore, the temperature distribution inside the permanent magnet holder is uniform, promoting uniform heating. That is, uneven heating of the entire permanent magnet holder is suppressed, heating efficiency is good, and the permanent magnet is also uniformly heated by the resin material, which acts as a binder in the permanent magnet holder. As a result, the permanent magnet can be demagnetized in a short time, and the adhesive function of the resin material can be rendered ineffective under conditions that suppress cracking and oxidation, thus recovering the permanent magnet and helping to significantly reduce waste generation. In addition, electricity used for heating can be saved, thereby reducing environmental impact such as carbon dioxide emissions.

[0022] In the permanent magnet recycling device of (2), by making the penetration depth of the insulation material greater than that of the resin material, the amount of microwaves absorbed by the insulation material can be suppressed, and the resin material as an adhesive can be effectively heated.

[0023] In the permanent magnet recycling device of (3), by setting the size of the insulation material in a way that does not exceed the thickness of 50 mm for insulation effect saturation, the waste of insulation material can be avoided.

[0024] In the permanent magnet recycling method of (4), heat dissipation from the end side of the laminated steel plate, which is difficult to heat with microwaves, is suppressed by using a microwave-penetrating insulating material. On the other hand, this end side does not obstruct microwave penetration into the resin material, which acts as a binder. Therefore, the temperature distribution inside the permanent magnet holder is uniform, promoting uniform heating. That is, uneven heating of the entire permanent magnet holder is suppressed, heating efficiency is good, and the permanent magnet is also uniformly heated by the resin material, which acts as a binder in the permanent magnet holder. As a result, the permanent magnet can be demagnetized in a short time, and the adhesive function of the resin material can be rendered ineffective under conditions that suppress cracking and oxidation, thus recycling the permanent magnet and helping to significantly reduce waste generation. In addition, electricity used for heating can be saved, thereby reducing environmental impact such as carbon dioxide emissions.

[0025] In the permanent magnet recycling method of (5), by making the penetration depth of the insulation material greater than that of the resin material, the amount of microwaves absorbed by the insulation material can be suppressed, and the resin material as an adhesive can be effectively heated.

[0026] In the permanent magnet recycling method of (6), the size of the insulation material can be set in such a way that the thickness does not exceed 50 mm to achieve the insulation effect saturation, thus avoiding the waste of insulation material. Attached Figure Description

[0027] Figure 1This is a conceptual diagram illustrating a permanent magnet recycling device according to an embodiment of the present invention.

[0028] Figure 2 This is a diagram illustrating the steps of installing the insulation material in the permanent magnet recycling method according to an embodiment of the present invention.

[0029] Figure 3 This is a line graph that helps in selecting insulation materials for use in embodiments of the present invention.

[0030] Figure 4 This is a flowchart illustrating the steps of a permanent magnet recycling method according to an embodiment of the present invention.

[0031] Figure 5 It is a graph illustrating the relationship between the thickness of the insulation material and the insulation effect in embodiments of the present invention. Detailed Implementation

[0032] Next, embodiments of the present invention will be described with reference to the accompanying drawings. In the following figures, the same or corresponding parts are labeled with the same symbols. Figure 1 This is a conceptual diagram illustrating a permanent magnet recycling device 1 according to an embodiment of the present invention. Figure 2 This is a diagram illustrating the steps of installing the insulation material in the permanent magnet recycling method according to an embodiment of the present invention. Figure 3 This is a flowchart illustrating the steps of a permanent magnet recycling method according to an embodiment of the present invention.

[0033] The permanent magnet recycling device 1 of this invention includes: a heat treatment furnace 2 for heating the material to be processed; and a microwave generating device 3 for radiating microwaves into the heat treatment furnace 2. The microwave generating device 3 is composed of a magnetron and a waveguide, etc. The heat treatment furnace 2 and the microwave generating device 3 constitute a microwave heating furnace 4. The permanent magnet recycling device 1 is in the form of a specific permanent magnet holder 5 being housed within the heat treatment furnace 2 of the microwave heating furnace 4 as the object to be heated, i.e., the material to be processed.

[0034] The permanent magnet holder 5 has a permanent magnet 8 mounted on a laminated steel plate 6 with an insulating film via a resin material 7, such as the rotor 9 of a dismantled rotating electric motor. This rotor 9 is a permanent magnet embedded rotor, also known as an Interior Permanent Magnet (IPM) rotor. IPM rotors retain many high-performance and expensive rare-earth magnets.

[0035] like Figure 2As shown, heat insulation material 10 is installed at a predetermined location on the permanent magnet holder 5, i.e., the rotor 9. In this example, microwave-permeable heat insulation material 10 is installed on the permanent magnet holder 5, at least within the range that contacts the resin material 7 at both ends in the lamination direction of the laminated steel plate 6. As a result, the rotor 9 becomes a processed material 11 with heat insulation material 10 installed in a predetermined configuration in each region of the peripheral portion of its axial end faces.

[0036] As insulation material 10, an insulation material with a microwave penetration depth greater than that of the adhesive, i.e., the resin material, is used. (Reference) Figure 3 The graph shows the relationship between the relative permittivity of the material, the dielectric loss angle, and the microwave penetration depth (microwave frequency is 2450MHz). A suitable material is selected as this insulation material 10. The penetration depth is the distance at which the power density of the irradiated electromagnetic wave is halved, also known as the power halving depth.

[0037] Figure 3 In this context, "MW" is an abbreviation for microwave. The double-headed arrow between "MW penetration" and "MW absorption" indicates that the deeper the penetration depth, the easier it is for microwaves to penetrate. Materials that are more easily penetrated by microwaves experience less temperature rise with microwave irradiation time, making them more suitable as insulation material 10. In selecting a suitable material for insulation material 10, in addition to the aforementioned penetration depth, heat resistance and toxicity are also considered. The resin material in this embodiment of the invention is epoxy resin. Considering durability and toxicity, alumina-based or silica-based insulation materials such as alumina (AL2O3), quartz (SiO2), and steatite (MgO·SiO2) are deemed suitable as insulation material 10.

[0038] Next, the permanent magnet recycling method according to the embodiments of the present invention will be described. Figure 4 This is a flowchart illustrating the steps of a permanent magnet recycling method according to an embodiment of the present invention. Figure 4 As shown, the permanent magnet recycling method includes an insulation material installation step S1 and a microwave heating step S2. The insulation material installation step S1 is to... Figure 2 The step is to shape the rotor 9 into the form of the material 11 to be processed. In the next microwave heating step S2, the material 11 to be processed is placed in the heat treatment furnace 2 of the microwave heating furnace 4 and heated by microwaves from the microwave generating device 3.

[0039] For example, using a radiation thermometer (not shown), from... Figure 1The upper surface temperature of the material 11 is measured in the direction directly opposite to the upper end face of the material 11, as indicated by the middle arrow A. The side surface temperature of the material 11 is measured in the direction directly opposite to the outer peripheral surface of the material 11, as indicated by the arrow B. This allows for estimation of the heating status of the material 11.

[0040] If a suitable material is used as the insulation material 10 in the laminated steel plate 6 of the material being treated 11, the upper surface temperature and side surface temperature of the material being treated 11 exhibit the following trend during microwave irradiation: While the side surface temperature of the material being treated 11 rises relatively rapidly and reaches a relatively high value, the upper surface temperature of the material being treated 11 rises relatively slowly and remains at a relatively low value. As the upper surface temperature and side surface temperature of the material being treated 11 exhibit this trend and progress, when the side surface temperature reaches, for example, above 175°C, it can be estimated that the interior of the material being treated 11 is uniformly heated to the point where the function of the resin material as an adhesive fails.

[0041] However, the inventors observed in their experiments that although the insulation effect of the insulation material 10 depends on its thickness, it will become saturated when the thickness reaches a certain value. Figure 5 This is a graph showing the relationship between the upper surface temperature and side surface temperature of the treated material 11 after microwave overheating and the thickness of the insulation material 10. Furthermore, the resin material used in the experiment was epoxy resin, and the insulation material was an alumina-based insulation material. Figure 5 As shown, the greater the thickness of the insulation material 10, the more pronounced the insulation effect and the better it suppresses the upper surface temperature. However, if the thickness reaches 50 mm, it tends to saturate. That is, even if the thickness of the insulation material 10 is greater than 50 mm, the effect of suppressing heat dissipation will not increase. Therefore, although the side temperature, which reflects the internal temperature of the treated material 11, will rise up up to the thickness of the insulation material 10 reaching 50 mm, it is estimated that even if the thickness is greater than 50 mm, it will saturate due to increased heat dissipation. Therefore, to avoid wasting insulation material and ensure the insulation effect, a thickness of 50 mm for the insulation material 10 is appropriate.

[0042] The permanent magnet recycling apparatus and method according to this embodiment have the following effects.

[0043] The permanent magnet recycling apparatus 1 of (1) includes: a heat treatment furnace 2 housing a permanent magnet holder 5, wherein a permanent magnet 8 is mounted on a laminated steel plate 6 having an insulating film via a resin material 7, and a microwave-permeable heat-insulating material 10 is provided at least within the range in contact with the resin material 7 at both ends of the laminated steel plate 6 in the lamination direction; and a microwave generating apparatus 3 that applies microwaves into the heat treatment furnace 2. Thus, the microwave-permeable heat-insulating material 10 suppresses heat dissipation from the end sides of the laminated steel plate 6, which are difficult to heat with microwaves, while the end sides do not obstruct microwave penetration into the resin material 7, which acts as an adhesive. Therefore, the temperature distribution inside the permanent magnet holder 5 is uniform, promoting uniform heating. Thus, the permanent magnet 8 is also uniformly heated via the resin material 7, which acts as an adhesive in the permanent magnet holder 5. Thus, the permanent magnet 8 can be demagnetized in a short time, and the adhesive function of the resin material 7 can be rendered ineffective under conditions that suppress cracking and oxidation, allowing the permanent magnet 8 to be recycled, thereby significantly reducing waste generation. In addition, it can save electricity used for heating, thus reducing environmental impact such as carbon dioxide emissions.

[0044] In the permanent magnet recycling device 1 of (2), by making the penetration depth of the heat insulation material 10 greater than that of the resin material 7, the amount of microwaves absorbed by the heat insulation material 10 can be suppressed, and the resin material 7, which is used as an adhesive, can be effectively heated.

[0045] In the permanent magnet recycling device of (3), by setting the size of the insulation material 10 in such a way as to not exceed a thickness of 50 mm that saturates the insulation effect, the waste of the insulation material 10 can be avoided.

[0046] The permanent magnet recycling method in (4) includes: a heat insulation material installation step S1, in which a microwave-permeable heat insulation material 10 is installed on a permanent magnet holder 5, on which a permanent magnet 8 is installed via a resin material 7 on a laminated steel plate 6 having an insulating film, at least within a range in contact with the resin material 7 at both ends of the laminated steel plate 6 in the lamination direction; and a microwave heating step S2, in which the permanent magnet holder 5, on which the heat insulation material 10 is installed in the heat insulation material installation step S1, is heated using a microwave heating furnace 4. Thus, the microwave-permeable heat insulation material 10 suppresses heat dissipation from the end side of the laminated steel plate 6, which is difficult to heat with microwaves, while the end side portion does not obstruct microwave penetration into the interior of the resin material 7, which acts as an adhesive. Therefore, the internal temperature distribution of the permanent magnet holder 5 is uniform, promoting uniform heating. That is, uneven heating of the entire permanent magnet holder 5 is suppressed, resulting in good heating efficiency. This allows for the demagnetization of the permanent magnet 8 in a short time, and the failure of the adhesive function of the resin material 7 under conditions of suppressed cracking and oxidation, enabling the recycling of the permanent magnet 8 and thus significantly reducing waste generation. Furthermore, it saves electricity used for heating, thereby reducing environmental impact, such as carbon dioxide emissions.

[0047] In the permanent magnet recycling method of (5), by making the penetration depth of the heat insulation material 10 greater than that of the resin material 7, the amount of microwaves absorbed by the heat insulation material 10 can be suppressed, and the resin material 7, which is used as an adhesive, can be effectively heated.

[0048] In the permanent magnet recycling method of (6), by setting the size of the insulation material 10 in such a way as to not exceed a thickness of 50 mm that saturates the insulation effect, the waste of the insulation material 10 can be avoided.

[0049] The embodiments of the present invention have been described above, but the present invention is not limited thereto. Details may be appropriately modified within the scope of the spirit of the invention. For example, the above description pertains to a permanent magnet holder being a rotary motor rotor from which the permanent magnet is recovered, but it can also be applied to cases where the permanent magnet holder is a medical device using permanent magnets and where the permanent magnet is recovered from the medical device.

[0050] Figure Labels

[0051] 1. Permanent magnet recycling device

[0052] 2 Heat treatment furnace

[0053] 3 Microwave generating device

[0054] 4. Microwave heating oven

[0055] 5. Permanent magnet retainer

[0056] 6-layer steel plate

[0057] 7. Resin materials

[0058] 8 Permanent magnets

[0059] 9 rotors

[0060] 10 Thermal insulation materials

[0061] 11. Materials being processed

Claims

1. A permanent magnet recycling device, comprising: A heat treatment furnace housing a permanent magnet holder, wherein the permanent magnet holder has a permanent magnet mounted on a laminated steel plate having an insulating film via a resin material, and a microwave-permeable heat-insulating material is mounted on the peripheral portion of both end faces of the laminated steel plate in the lamination direction, within a range at least in contact with the resin material; and, The microwave generating device applies microwaves into the aforementioned heat treatment furnace. The aforementioned permanent magnet recycling device is characterized in that, The aforementioned thermal insulation material has a greater penetration depth into the aforementioned microwaves than the aforementioned resin material. The aforementioned thermal insulation material does not obstruct microwave penetration into the interior of the aforementioned resin material at the end portion of the aforementioned laminated steel plate.

2. The permanent magnet recycling device according to claim 1, wherein, The aforementioned resin material is epoxy resin, the aforementioned insulation material is an alumina-based or silica-based insulation material, and the thickness of the aforementioned insulation material is less than 50 mm.

3. A method for recycling permanent magnets, comprising: The insulation material installation steps involve installing microwave-permeable insulation material on a permanent magnet holder on a laminated steel plate with an insulating film, specifically on the periphery of both end faces of the laminated steel plate in the lamination direction, within a range that is at least in contact with the aforementioned resin material; and... In the microwave heating step, a microwave oven is used to heat the permanent magnet holder in which the aforementioned insulation material was installed during the aforementioned insulation material installation step. The aforementioned method for recycling permanent magnets is characterized by, The aforementioned thermal insulation material has a greater penetration depth into the aforementioned microwave than the aforementioned resin material. In the aforementioned microwave heating step, microwaves penetrate the aforementioned thermal insulation material to reach the aforementioned resin material, thereby ensuring that the temperature distribution inside the aforementioned permanent magnet remains uniform.

4. The method for recycling permanent magnets according to claim 3, wherein, In the aforementioned insulation material installation step, the insulation material with a penetration depth greater than that of the aforementioned resin material is installed at both ends in the stacking direction of the aforementioned laminated steel plate.

5. The method for recycling permanent magnets according to claim 4, wherein, The aforementioned resin material is epoxy resin, and the aforementioned insulation material is an alumina-based or silica-based insulation material with a thickness of less than 50 mm.

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