JP2014150185A - Recovery method of magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that when recovering a magnet from a used product where a plurality of kinds of magnet (e.g., a Nd-based magnet and a Sm-based magnet) are fixed to one rotor body or the like, the magnets having lost the magnetic force are detached from the rotor body or the like if the magnets are heated to a temperature equal to or higher than a Curie temperature of all kinds of magnet, and various magnets are mixed and cannot be sorted easily.SOLUTION: In the recovering method of magnets, the magnets are covered with a magnetic shield material (ferromagnetic material such as iron), and then the magnets to be recovered are heated to a temperature equal to or higher than the Curie temperature. Since the magnetic shield material fixed by the magnetic force before heating treatment is fixed, as it is, at the part of a Sm-based magnet and separated together with the Nd-based magnet at the part of a Nd-based magnet after heating treatment, the Nd-based magnets can be recovered easily without being mixed with the Sm-based magnets.

Description

  The present invention relates to recycling of used magnets.

  Against the background of soaring rare earth resources, the need for domestic circulation of these resources is increasing. Rare earths are an important resource for improving product efficiency, performance, and miniaturization, and are used in many products in Japan, including motors. Products using rare earth magnets include room air conditioners, refrigerators and dehumidifiers for home appliances, and servo motors and elevator hoisting motors for industrial products. With regard to home appliances, there is an enforcement of the Home Appliance Recycling Law, etc., and development of rare metal recovery technology is progressing. For example, Patent Document 1 and Patent Document 2 disclose a method for recovering rare earth magnets from used products. Has been. Patent Document 1 describes that a used product is crushed together with a magnet by a crusher, and magnet material is collected by magnetic separation or the like. Patent Document 2 describes that a rare earth magnet is positively brittle by heat treatment in a hydrogen atmosphere and recovered in powder form.

JP 2010-192575 A JP 2012-062532 A

  However, in the conventional techniques disclosed in Patent Document 1 and Patent Document 2, in order to pulverize the magnets to be collected, a plurality of types (for example, combinations of Nd-based magnets and Sm-based magnets) are used like a motor of a washing machine. ) Is incorporated in one rotor, if the entire rotor is crushed, the pulverized powder of the Nd magnet and the pulverized powder of the Sm magnet are mixed and separated and recovered. This is a problem because it may be inefficient and inefficient and may affect the magnetic properties of recycled Nd magnets if Sm magnet powders are mixed with Nd magnet powders. .

  Therefore, the present invention has been made to solve the above problems, and even in a motor in which a plurality of types of magnets are fixed, other types of magnets are mixed in the magnets to be collected. It aims at providing the method of collect | recovering efficiently, without.

  The magnet recovery method according to the present invention includes a first magnet and a first magnet from a separation object in which a second magnet having a Curie temperature higher than that of the first magnet is fixed via an organic material. A magnet recovery method for separating and recovering magnets, wherein at least one of the first magnet and the second magnet is covered with a magnetic shield material, and after the preparation step, the temperature is equal to or higher than the Curie temperature of the first magnet. A heating step for heating the separation target in a temperature range that is equal to or lower than the same temperature of the second magnet and the organic material is thermally decomposed, and the first separated from the separation target in the heating step A magnet recovery method comprising a recovery step of recovering a magnet.

  Since the magnet recovery method according to the present invention is configured as described above, it is possible to efficiently recover a magnet to be recovered without mixing other types of magnets.

It is a flowchart of the magnet collection process which concerns on Embodiment 1 of this invention. It is a schematic diagram of the structure which performs the magnet collection | recovery which concerns on Embodiment 1 of this invention. It is the conceptual diagram of the magnet separation which looked at the magnet collection process which concerns on Embodiment 1 of this invention in order of the flow.

Embodiment 1 FIG.
First, the magnet recovery process in the embodiment of the present invention will be described with reference to the drawings. The drawings are schematic and do not reflect the exact size of the components shown. Moreover, what attached | subjected the same code | symbol is the same or equivalent, and this is common in the whole text of a specification.

  In this embodiment, an example will be described in which a magnet is collected from a used product in which the magnet is fixed to the rotor body of the motor. In this embodiment, a case where a plurality of types of magnets (for example, an Nd-based magnet 2 as a first magnet and an Sm-based magnet 3 as a second magnet) is fixed to one rotor body or the like will be described as an example.

First, the overall configuration of the magnet recovery process according to this embodiment will be described. FIG. 1 is a flowchart of a magnet recovery process according to this embodiment.
The magnet recovery method is
(1) Preparation process of covering each magnet with a magnetic shielding material (ferromagnetic material such as iron),
(2) A heating step of heating in a temperature range that is equal to or higher than the Curie temperature of the first magnet and equal to or lower than that of the second magnet, and in which the adhesive or molding material is thermally decomposed,
(3) A recovery process for recovering the first magnet dropped from the used product,
It is comprised from the process including.

  Further, the magnet recovery process will be described in detail. FIG. 2 is a perspective view schematically showing the state of the rotor during the process of collecting the magnet and during the collecting process from the preparation process described later. FIG. 3 is a conceptual diagram of a magnet recovery process in which magnet recovery is viewed in flow order. FIG. 3 is a plan view of the rotor in FIG. 2 and is viewed in the flow order.

Referring to FIG. 2, the rotor of the motor, which is a used product, is placed on gantry 7. A plurality of types of magnets (Nd magnet 2 and Sm magnet 3) are fixed to the rotor body 1. The fixing method is an organic material such as an adhesive or a mold resin. For example, an epoxy adhesive, polypropylene resin, polyamide resin, ABS resin (acrylonitrile-butadiene-styrene copolymer synthetic resin), PBT resin (polybutylene terephthalate resin), PPS resin (polyphenylene sulfide resin) or the like as a main component. An organic material is assumed. These organic resins may be mixed with inorganic fillers called fillers such as glass fibers.
Also. The gantry 7 is supported by a column 9. Therefore, a space 8 wider than the size of the first magnet 5 to be collected is secured at the bottom of the gantry 7. Further, the gantry 7 is provided with an opening 10 sufficient to allow the recovery magnet 5 that is separated from the rotor body to fall. For easy understanding, the Nd-based magnet 2 and the Sm-based magnet 3 are depicted through the magnetic shield material 4.

  Further, a magnetic shield material 4 for magnetically shielding these magnets covers the Nd-based magnet 2 and the Sm-based magnet 3. Further, the magnetic shield material 4 is provided with openings 6 in the upper and lower portions in the drawing. The opening 6 is a gap formed between the magnetic shield material 4 and the rotor body 1 when the magnetic shield material 4 is fixed to the separation object (the rotor body 1), and the Nd-based magnet 2 can pass therethrough. It is a large size. In other words, the magnetic shield material has such a shape that an opening through which the first magnet can pass is formed between the magnetic shield material and the separation object.

Next, a process for recovering the Nd-based magnet 2 from the rotor of the motor that is a used product will be described in detail in the order of flow with reference to FIG.
Referring to FIG. 3A, a used product in which Nd-based magnets 2 and Sm-based magnets 3 are alternately fixed to the rotor main body 1 of the motor with an adhesive is placed on a gantry 7. The gantry 7 is not shown in FIG. 3 in order to avoid complexity.

Here, the rotor of the motor is placed on the gantry 7, but this is not an essential requirement.
However, it is also possible to provide a space 8 as shown in FIG. 2 at the lower part of the rotor so that the magnetic shield material 4 has an open surface facing the space (that is, the opening 6). That is, when the Nd magnet is demagnetized in the heating process described later, the Nd magnet 2 falls into the space 8 below the rotor through the opened surface (opening 6), and a sufficient distance from the Sm magnet 3 is obtained. Therefore, even if the magnetic shield material 4 does not have a closed structure, the Nd-based magnet 2 can be prevented from being attracted to the Sm-based magnet 3 after cooling.

  Next, as a preparation step, a magnetic shield material made of iron is fixed to the rotor body 1. In this embodiment, the Nd magnet 2 and the Sm magnet 3 are individually covered with a magnetic shield material. In addition to iron, a ferromagnetic material such as permalloy can be used as the magnetic shield material. This process is the state shown in FIG.

  Here, the magnetic shield material 4 and related matters will be described. In FIG. 3, the magnetic shield material 4 is illustrated so as to cover the magnets (Nd-based magnet 2, Sm-based magnet 3), but when the Nd-based magnet 2 is recovered, the Nd-based magnet 2 sticks to the Sm-based magnet 3. It does not have to be completely covered.

  The thickness of the magnetic shield material 4 is not particularly limited, but is preferably 0.5 mm or more and 2 mm or less from the viewpoint of handling. When the thickness is 0.5 mm or less, the member is deformed during repeated use and it becomes difficult to reuse, and when the thickness is 2 mm or more, the member becomes heavy, and the magnetic force described above. This is because the fixing by may not be possible even after heat treatment.

  Further, as the heating process, the magnet-attached rotor main body 1 to which the magnetic shield material 4 is fixed is not less than the Curie temperature of the Nd magnet and not more than the Curie temperature of the Sm magnet in vacuum or in an inert gas (for example, 350 to (450 ° C.). This process is the state shown in FIG. In the heating in such a temperature range, the Nd magnet 2 can be demagnetized and the adhesive can be decomposed at the same time. During the heat treatment, the Nd-based magnet loses its magnetic force at the same time as the adhesive is decomposed and the adhesive force between the magnet and the rotor disappears. Therefore, the magnetic shield material 4 and the Nd-based magnet 2 fixed by the magnetic force are separated from the rotor body 1. In this embodiment, the Nd-based magnet 2 that has lost the magnetic force falls into the space 8 below the gantry 7. In this embodiment, the Nd magnet 2 separated from the rotor body 1 is expressed as a recovery magnet 5.

  On the other hand, the portion of the Sm magnet 3 remains fixed to the rotor body 1 by the magnetic force of the Sm magnet 3 even if the adhesive is decomposed.

  In addition, although it put into the heating furnace 20 and the heat processing atmosphere is made into the vacuum or inert gas, the same effect is acquired also in air | atmosphere. However, heating in the atmosphere may cause the magnet to oxidize, and if oxygen is mixed into the recovered magnet, the magnetic properties of the regenerated magnet made from it will be deteriorated, so an atmosphere with oxygen was avoided. Is preferable.

  After the heat treatment is finished and cooled, the Nd magnet 2 is separated from the rotor body 1, and the Sm magnet 3 remains fixed to the rotor body 1 together with the magnetic shield material 4, so that only the Nd magnet 2 is easily recovered. It becomes possible to do. This process is the state (D) of FIG. 3 and is a recovery process.

  In addition, even if the adhesive is decomposed in the heat treatment temperature range described above, the magnet and the rotor body 1 may not be completely separated. Therefore, the magnet and the rotor are separated by applying vibration during the heat treatment or after cooling. It may be easy to do. The term “vibration” as used herein includes micro-vibration caused by ultrasonic waves and mechanical impacts using a hammer.

  Although the collection method of the magnet to be collected is completed as described above, the collection method in the case of collecting and reusing the magnetic shield material 4 that is fixed to the rotor after the Nd magnet 2 can be collected will be described. . Although the magnetic shield material 4 is fixed by the magnetic force of the Sm-based magnet 3, the magnetic force of the Sm-based magnet 3 is lower than that before the heat treatment because the Sm-based magnet 3 is heated at several hundred degrees Celsius. In some cases, it can be separated by hand, but if it cannot be separated by hand, it can be separated using an external magnetic force or an impact force. When using magnetic force, for example, a rare earth magnet can be used. However, since an additional means for separating the magnetic shield fixed to the rare earth magnet is required, it is preferable to use an electromagnet. By using an electromagnet, a magnetic force can be generated when necessary by current control, and the magnetic force can be lost when unnecessary. The magnetic force can be controlled by adjusting the current. For this reason, the electromagnet is easy to handle and convenient for collecting the magnetic shield material.

  As described above, only the magnet to be collected can be collected by the magnet collection process of the present invention. Further, the presence of the magnetic shield material 4 causes the Nd magnet 2 to stick to the Sm magnet 3 after finishing the heat treatment and cooling, or the Nd magnet 2 breaks due to the impact when sticking to the Sm magnet 3. Can be prevented. Therefore, it can collect | recover efficiently, without mixing another kind of magnet with the magnet made into collection | recovery object.

The above-described mode is merely an example, and any method may be used as long as the Nd-based magnet can be recovered without sticking to the Sm-based magnet, and the flow of FIG. 1 can be realized. Further, in this embodiment, an example in which a magnet is attached to the outside of the rotor body has been taken up, but the recovery process in this embodiment can be similarly applied even when a magnet is attached to the inside of the rotor body.
Further, the separation object may not be a rotor, and the present invention can be applied to a stator. Further, the present invention can be applied even if the separation object is not a motor but a generator.

  In addition, the Nd-based magnet and the Sm-based magnet have been described as examples. However, since the selection is performed using the difference in Curie temperature, the present invention can be applied to other types of magnets.

Further, in the first embodiment, the magnetic shield material 4 is attached to the Nd-based magnet 2 and the Sm-based magnet 3 to perform magnetic shielding. However, since it is sufficient that the Nd-based magnet 2 does not stick to the Sm-based magnet 3, the magnets do not stick to each other if at least one of the Nd-based magnet 2 or the Sm-based magnet 3 is covered with a magnetic shield material. Therefore, the form which covers at least one among a 1st magnet or said 2nd magnet with a magnetic shielding material may be sufficient.
Further, from the viewpoint of work efficiency, the target to be magnetically shielded may be selected according to the Nd-based magnet 2 to be collected, and one of all the Nd-based magnets 2 or all of the Sm-based magnets 3 is magnetized one by one. There is no need to cover with shielding material.

  It should be understood that the above-described embodiment is illustrative in all respects and not restrictive. The scope of the present invention is not limited to the above-described embodiment, but is defined by the scope of the claims, and includes meanings equivalent to the scope of the claims and all modifications within the scope.

  DESCRIPTION OF SYMBOLS 1 Rotor main body, 2 Nd type | system | group magnet, 3 Sm type | system | group magnet, 4 Magnetic shield material, 5 Recovery magnet, 6 Opening part, 7 mounts, 8 spaces, 9 support | pillars, 10 support openings, 20 heating furnaces.

Claims (5)

A magnet for separating and recovering the first magnet from a separation object in which a first magnet and a second magnet having a Curie temperature higher than that of the first magnet are fixed via an organic material. A collection method,
A preparation step of covering at least one of the first magnet and the second magnet with a magnetic shielding material;
After the preparation step, a heating step of heating the separation object in a temperature range that is not less than the Curie temperature of the first magnet and not more than the same temperature of the second magnet, and the organic material is thermally decomposed, and A magnet recovery method comprising: a recovery step of recovering the first magnet separated from the separation object in a heating step.   The magnet recovery method according to claim 1, wherein a rotor of a motor provided with an Nd-based magnet as the first magnet and an Sm-based magnet as the second magnet is an object to be separated.   The magnet recovery method according to claim 1, wherein in the preparation step, the first magnet and the second magnet are individually covered with a magnetic shield material.   A magnetic shield having a shape in which an opening through which the first magnet can pass is formed between the magnetic shield material and the separation object in the preparation step when individually covering the first magnet with the magnetic shield material The method for recovering a magnet according to claim 1, wherein a material is used. In the case of covering the second magnet with a magnetic shield material, and when collecting the magnetic shield material remaining on the separation object after the collection step,
The magnet recovery method according to claim 1, further comprising a step of attaching the magnetic shield material to an electromagnet to separate and recover the magnetic shield material from the separation target.

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