JP5816123B2 - Permanent magnet recovery method - Google Patents

Description

  The present invention relates to a method for recovering a permanent magnet such as a neodymium magnet.

  Electric motors (motors) are used in various products such as home appliances and various industrial equipments. In recent years, hybrid vehicles that run on motors and engines and electric vehicles that run only on motors have started to become popular in automobiles. It is spreading more and more.

  There are many types of motors such as induction motors and brushless DC motors. From the viewpoint of improving the energy efficiency of motors, in recent years, permanent magnets that do not require field currents required for induction motors and have no secondary copper loss are used. The used internal magnet (IPM) motor has been widely used.

  FIG. 1 is a cross-sectional view showing a structural example of the IPM motor M. The permanent magnet 1 is fixed by a magnet fixing mold material made of an oxide and a binder, and is embedded in a rotor (rotor) 3 made of an electromagnetic steel plate. A stator (stator) 2 is provided outside the rotor 3, and the rotor 3 is rotated by passing an electric current through the coil 4 wound around the slot. According to the IPM motor M, the magnetic flux density can be increased by using a strong rare earth magnet, and the output of the motor can be improved and the size can be reduced.

  There are two main types of rare earth magnets used in the IPM motor M: samarium / cobalt magnets and neodymium / iron / boron magnets (neodymium magnets). They have a high magnetic energy product and are excellent in mechanical strength. Therefore, neodymium magnets are often used, accounting for 90% or more of rare earth magnets.

  Rare earth elements such as neodymium (Nd), dysprosium (Dy), and praseodymium (Pr) used in neodymium magnets are not only expensive, but also have limited production countries. Therefore, an efficient recycling method is strongly desired.

  However, although the recycling of neodymium magnets in the manufacturing process is being reused, the recycling of rare earth magnets acquired from equipment such as used motors or generators has not progressed. It is.

  One major reason that makes it difficult to recycle magnets obtained from used equipment is that rare earth magnets are strongly bonded to magnetic steel sheets and stainless steel by magnetic force, and there are molding materials for fixing magnets. This is because it is difficult to efficiently remove and collect the magnet from the rotor manually.

  Under such circumstances, it is very difficult to collect magnets such as motors at present, but if the magnets are contained in the pulverized product after pulverizing the product, the magnets are made of iron such as crushers and conveyors. It adheres to parts and hinders the recycling of valuable metals such as iron and copper. Therefore, demagnetization of permanent magnets has been intensively studied as a pretreatment for recovering valuable metals such as copper, aluminum and iron.

  As a prior art of such a demagnetizing method of a permanent magnet, a method of demagnetizing a product including a permanent magnet by heating in a heating furnace (for example, see Patent Documents 1 and 2), or applying a high frequency voltage to a motor voltage However, a method has been proposed in which the motor generates heat by an induced current and is demagnetized (see, for example, Patent Documents 3, 4, and 5).

  However, if the product is heated by the above method and the magnet is demagnetized, the rare earth magnet will be heated in the air, and the rare earth element will form an oxide. In order to reuse it as a magnet again, it is necessary to newly reduce the magnet. In this case, even if the magnet component is separated and recovered, chemical recycling of the magnet is required, resulting in poor recycling efficiency.

JP 2001-110636 A JP 2001-313210 A Japanese Patent No. 3835126 JP 2006-254699 A JP 2009-291070 A

  There is a method of recovering a permanent magnet after heat-treating a motor having a permanent magnet with superheated steam in a demagnetizing furnace. In this case, the permanent magnet that is the object to be processed can be rapidly heated by the combined heat transfer of convection, radiation, and condensation.

  However, oil or the like is attached to the permanent magnet introduced into the demagnetization furnace, and it is not preferable to perform demagnetization treatment on the permanent magnet in this state from the viewpoint of improving demagnetization efficiency. Further, there arises a problem that the demagnetizing furnace is contaminated by oil or the like adhering to the permanent magnet.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for recovering a permanent magnet that can efficiently demagnetize the permanent magnet and suppress contamination in the demagnetization furnace. That is.

The permanent magnet recovery method according to the present invention includes a demagnetizing furnace that demagnetizes a permanent magnet attached to a motor using superheated steam, a first supply line that supplies the superheated steam to the demagnetizing furnace, and a preheating furnace. And a permanent magnet recovery system having a second supply line for supplying superheated steam of the demagnetization furnace to the preheating furnace,
Preheating the permanent magnet in the preheating furnace;
The demagnetizing furnace further includes a step of further heating the preliminarily heated permanent magnet.

  The above-mentioned superheated steam refers to steam having a temperature of 100 ° C. or higher at normal pressure.

  In this permanent magnet recovery system, superheated steam is supplied to the demagnetization furnace through the first supply line, and the permanent magnet is demagnetized by heating with the superheated steam. And it is comprised so that the superheated steam of a demagnetizing furnace may be supplied to a preheating furnace by a 2nd supply line. In this system, according to the recovery method of the present invention, the permanent magnet is first preliminarily heated in the preheating furnace. The preliminarily heated permanent magnet is demagnetized by further heating in a demagnetizing furnace. The permanent magnet thus demagnetized and recovered can be reused in an electric motor, a generator or the like after being magnetized again.

  As a form of the workpiece to be introduced into the preheating furnace and the demagnetization furnace, a permanent magnet fixed to the rotor can be adopted. Hereinafter, the permanent magnet fixed to the rotor may be referred to as an object to be processed.

  By supplying superheated steam to the preheating furnace, the superheated steam comes into contact with a relatively low temperature object to be processed, and the object to be processed is gradually heated. At this time, oil or the like adhering to the object to be processed can be detached from the object to be processed by coming into contact with the dew condensation water, and the contaminant concentration of the object to be processed can be reduced. As a result, the object to be processed can be cleaned before being introduced into the demagnetizing furnace, so that the object to be processed can be efficiently demagnetized and the inside of the demagnetizing furnace is contaminated by oil adhering to the object to be processed. It can be suppressed. Further, since the superheated steam used for the preheating is used in the demagnetization furnace, it is not necessary to newly prepare the superheated steam for the preheating, and the process can be performed at low cost.

  Condensed water condensed on the object to be treated is received at the lower part of the preheating furnace and discharged out of the system, thereby suppressing contamination in the preheating furnace and facilitating maintenance in the furnace.

  In the present invention, it is preferable to use a superheated steam having a temperature of 110 ° C. or higher.

  Specifically, the temperature of the superheated steam supplied to the demagnetization furnace through the first supply line is preferably 450 ° C to 550 ° C, and more preferably 460 ° C to 540 ° C. Moreover, it is preferable that the temperature of the superheated steam supplied to a preheating furnace by a 2nd supply line shall be 100 degreeC or more.

  In the present invention, the permanent magnet may be fixed to a rotor or a stator of a motor via a resin material.

  In the present invention, the permanent magnet used in the electric motor or generator may be recovered.

  In the present invention, a neodymium magnet may be recovered as the permanent magnet.

  According to the present invention, the workpiece can be cleaned by preliminarily heating the workpiece with the superheated steam used in the demagnetization furnace. Thereby, while being able to demagnetize a to-be-processed object efficiently in a demagnetizing furnace, it can suppress that the inside of a demagnetizing furnace is contaminated with the oil etc. which adhered to the to-be-processed object.

It is sectional drawing of an internal magnet embedded type motor. It is a block diagram which shows the structure of the permanent magnet collection system for enforcing the collection method of the permanent magnet which concerns on this invention.

  Hereinafter, a method for recovering a permanent magnet according to an embodiment of the present invention will be described with reference to the drawings.

  Examples of the permanent magnet that can be recovered by the recovery method according to the present invention include the permanent magnet 1 attached to the IPM motor M described with reference to FIG. Below, the case where the permanent magnet 1 of the state fixed to the rotor 3 is processed as a to-be-processed object is demonstrated.

  The permanent magnet recovery system of FIG. 2 includes a preheating furnace 10, a demagnetizing furnace 11 that demagnetizes the permanent magnet 1 using superheated steam, a first supply line 12 that supplies superheated steam to the demagnetizing furnace 11, and a demagnetization. And a second supply line 13 for supplying superheated steam from the furnace 11 to the preheating furnace 10. An exhaust line 14 is connected to the preheating furnace 10.

  Said superheated steam means what heated up steam at the normal pressure to the temperature of 100 degreeC or more. By using superheated steam as a heating source, it becomes possible to rapidly heat an object to be processed by a combined heat transfer of convection, radiation, and condensation.

  The temperature of the superheated steam supplied to the demagnetization furnace 11 through the first supply line 12 can be set to 450 ° C to 550 ° C. Moreover, the temperature of the superheated steam supplied to the preheating furnace 10 by the 2nd supply line 13 can be 100 degreeC or more.

  In such a permanent magnet recovery system, first, the workpiece is preliminarily heated in the preheating furnace 10. By setting the heating time to 5 minutes to 60 minutes, the temperature of the object to be processed can be set to 100 ° C to 250 ° C.

  After the preheating is finished, the object to be processed is introduced into the demagnetizing furnace 11. In the degaussing furnace 11, the object to be processed is further heated by superheated steam and demagnetized. By setting the heating time to 5 minutes to 60 minutes, the temperature of the object to be processed can be set to 300 ° C to 400 ° C.

  In this way, by supplying superheated steam to the preheating furnace 10, the superheated steam comes into contact with a relatively low temperature object to be processed, and the object to be processed is gradually heated. At this time, oil or the like adhering to the object to be processed can be detached from the object to be processed by coming into contact with the dew condensation water, and the contaminant concentration of the object to be processed can be reduced. As a result, the object to be processed can be cleaned before being introduced into the demagnetizing furnace 11, so that the object to be processed can be efficiently demagnetized and the inside of the demagnetizing furnace 11 due to oil or the like adhering to the object to be processed. Can be remarkably suppressed from being contaminated. Further, since the superheated steam used for the preheating is used in the demagnetization furnace 11, it is not necessary to newly prepare the steam for the preheating, and the process can be performed at a low cost.

  The superheated steam after the treatment in the preheating furnace 10 and the superheated steam after the treatment in the demagnetizing furnace 11 can be liquefied and treated as waste water. Therefore, a large exhaust gas treatment facility is unnecessary.

  The permanent magnet 1 recovered by demagnetization can be reused in an electric motor, a generator, etc. after being magnetized again, and does not require processing such as pulverization, molding or processing again.

  Examples of magnetizing methods include a method of magnetizing with a static magnetic field using an electromagnet, a method of using a capacitor-type magnetizing power supply device to generate a strong pulsed magnetic field by passing a large current through a coil, etc. Is a preferred example. The magnetizing method using a pulsed magnetic field is particularly preferable because it can be magnetized in a short time and has high productivity per unit time. When magnetizing with a pulsed magnetic field, the voltage of the capacitor-type power supply is 1500 V or more and the capacitance of 2000 μF or more with respect to the neodymium magnet, and the pulse width is set to 1/1000 to 1/100 seconds. By doing so, sufficient magnetization can be performed, and the neodymium magnet can be returned to the same level as the magnetic force before demagnetization. In addition to the above-described method of magnetizing the recovered permanent magnet in its shape after demagnetization, the metal may be isolated by a treatment such as melting to form various metal species and alloys for magnetization.

  The present invention is not limited by the above-described embodiments, and can be implemented with appropriate modifications within a range that can be adapted to the gist of the present invention, all of which are within the technical scope of the present invention. Is included.

DESCRIPTION OF SYMBOLS 1 Permanent magnet 2 Stator 3 Rotor 4 Coil 10 Preheating furnace 11 Demagnetizing furnace 12 1st supply line 13 2nd supply line 14 Exhaust line M IPM motor

Claims (5)

A demagnetizing furnace that demagnetizes a permanent magnet attached to a motor using superheated steam, a first supply line that supplies the superheated steam to the demagnetizing furnace, a preheating furnace, and superheated steam from the demagnetizing furnace as the preliminary In a permanent magnet recovery system having a second supply line for supplying to a heating furnace,
Preheating the permanent magnet in the preheating furnace;
In the demagnetizing furnace, the method further comprises the step of further heating the preliminarily heated permanent magnet.   The method for recovering a permanent magnet according to claim 1, wherein the temperature of the superheated steam is 110 ° C. or higher.   The permanent magnet recovery method according to claim 1, wherein the permanent magnet is fixed to a rotor or a stator of a motor via a resin material.   The recovery method of the permanent magnet of any one of Claims 1-3 which collect | recovers the said permanent magnet currently used for the electric motor or the generator. The method for recovering a permanent magnet according to claim 1, wherein a neodymium magnet is recovered as the permanent magnet.

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