JP2014181370A - Method of recovering rare earth element and method of recycling steel ingredient - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of recovering rare earth elements easily from rare earth magnets incorporated in products and a method of recycling a steel ingredient contained in rare earth magnet motors by using the method of recovering rare earth elements.SOLUTION: A method of recovering rare earth elements from a motor using a rare earth magnet includes a step of melting a rotor 1 separated from the motor to obtain a molten metal 2, a step of introducing an oxidant 4 into the molten metal to form slag 3 containing rare earth oxides and a step of recovering the slag. After the slag recovery step of the recovery method, the remaining molten metal 5 after recovery of the slag is recycled as a steel raw material.

Description

  The present invention relates to a method for collecting rare earth elements and a method for reusing steel components. More specifically, the present invention relates to a method for recovering rare earth elements from a motor in which a rare earth magnet is used, and a method for reusing a steel component that reuses a steel component contained in a rare earth magnet motor.

In recent years, recycling technology related to rare earth elements has attracted attention. As is well known, rare earth elements are useful resources, and are used, for example, as magnets. Rare earth magnets containing rare earth elements can exert a large magnetic force in a small volume compared to other magnets, and thus contribute greatly to miniaturization of motors and are used in motors of various sizes. In particular, a hybrid motor or an electric vehicle incorporates a large motor for driving wheels. Many rare earth magnets are used in such large motors.
On the other hand, rare earth elements have problems that are unique to valuable resources, such as the risk of resource depletion and the risk of rising prices, due to the fact that there are few recoverable reserves and the location of mining is unevenly distributed. . For this reason, there is an urgent need to establish a mechanism that can efficiently recycle rare earth elements such as rare earth elements and their compounds contained in motors.
As techniques for recovering rare earth elements from rare earth magnets, the techniques of Patent Documents 1 to 3 below are known.

JP 2012-115815 A JP 2009-249664 A JP 2012-237053 A

Patent Document 1 discloses a method for recovering a rare earth magnet from a compressor or an electric motor used in an air conditioner, a refrigerator, or the like. Specifically, (1) a step of separating the iron core provided in the pump using a shaft extrusion mechanism, (2) a step of demagnetizing the iron core, (3) a step of taking out the magnet from the iron core, etc. A recovery method is disclosed.
However, the method of separating the magnet from the product by the method of Patent Document 1 requires a very complicated process. Thus, taking out rare earth magnets one by one from the product to be discarded results in a recycling cost. Will push up.

  In addition, Patent Document 2 and Patent Document 3 disclose a method of recovering rare earth elements as oxides by heating magnet scrap and waste powder discharged in the rare earth magnet manufacturing process in an oxidizing atmosphere. ing. However, no investigation has been made on how to recover rare earth magnets from products incorporating rare earth magnets such as motors. For this reason, the above technique has a problem that it cannot be used as it is for various products in which rare earth magnets are incorporated.

  In other words, to recycle rare earth elements, refining (refining process) to concentrate rare earth elements is performed as the final process. However, refining is not possible for products that incorporate rare earth magnets as one part, such as motors. Can not do. Therefore, it is necessary to disassemble and take out the magnet part.

However, the wheel driving motor and its parts are often used for caulking, and it is not easy to take out the rare earth magnet. Furthermore, since the rare earth magnet has a remarkably strong magnetic force compared to other magnets, it is difficult and dangerous to handle as it is, and there is also a problem that a separate demagnetization step is required if it is to be disassembled.
Under such circumstances, although there is a demand for a method for efficiently recovering rare earth elements from rare earth magnets incorporated in products, no solution has been reached.

  The present invention has been made in view of the above circumstances, and provides a method for recovering a rare earth element more easily from a rare earth magnet incorporated in a product and a method for reusing a steel component contained in a rare earth magnet motor. The purpose is to do.

The present invention is as follows.
The method for recovering a rare earth element according to claim 1 is a method for recovering a rare earth element from a motor using a rare earth magnet,
Melting the rotor separated from the motor to obtain a molten metal,
Introducing an oxidizing substance into the resulting molten metal to produce a slag containing rare earth oxides,
And a slag recovery step of recovering the slag.
The method for recovering a rare earth element according to claim 2 is characterized in that, in the method for recovering a rare earth element according to claim 1, the iron material is also melted together in the molten metal preparation step.
The rare earth element recovery method according to claim 3 is the rare earth element recovery method according to claim 1 or 2, wherein, in the molten metal preparation step, a material containing at least one of Al, Si, Mg, and Ti. Is to be dissolved together.
The method for recovering rare earth elements according to claim 4 is the method for recovering rare earth elements according to any one of claims 1 to 3, wherein in the molten metal preparation step, a magnetic shielding plate provided in the rotor is used. The gist is to dissolve together.
The method for recovering rare earth elements according to claim 5 is the method for recovering rare earth elements according to any one of claims 1 to 4, wherein oxygen is used as the oxidizing substance in the slag generation step. And
The rare earth element recovery method according to claim 6 is the rare earth element recovery method according to any one of claims 1 to 5, wherein, in the slag generation step, Al, Si, Mg are used as the oxidizing substance. And an oxide containing at least one of Ti and Ti.
The rare earth element recovery method according to claim 7 is the rare earth element recovery method according to any one of claims 1 to 6, further comprising a refining step of refining the slag and concentrating the rare earth element. The gist.
The method for reusing a steel component contained in the rare earth magnet motor according to claim 8 is the remaining after the slag is recovered in the slag recovery step in the rare earth element recovery method according to any one of claims 1 to 7. The main point is to reuse the molten metal as a raw material for steel.

According to the rare earth element recovery method of the present invention, the rare earth element can be easily recovered from the rare earth magnet incorporated in the product. In particular, it is possible to perform a large amount of processing at low cost without requiring a disassembling step for taking out the rare earth magnet or a demagnetizing step for the rare earth magnet. Moreover, in the molten metal preparation process and slag production | generation process in this method, the equipment in the steelmaking technique which has been constructed over a long time can be diverted. Therefore, new capital investment is small and high safety can be secured.
Further, the slag recovered by this method is an oxide containing a rare earth element in a concentrated manner. That is, since it is the same oxide as the ore, the rare earth element can be extracted and purified by the same method conventionally used for the ore. On the other hand, the slag recovered by this method does not contain radioactive materials such as thorium contained in many ores. For this reason, handling of the slag collected by this method is much easier than ores containing such radioactive materials.

In the melt preparation step in the rare earth element recovery method of the present invention, a material containing at least one of Al, Si, Mg, and Ti can be dissolved together. Among rare earth elements, Dy is known as an element having a large specific gravity, and even after it is formed as an oxide slag, the specific gravity is large and may not easily float in the molten metal. However, oxides composed of the above elements have a specific gravity that is smaller than that of Dy, and have the characteristics that oxides are likely to be formed as in the case of rare earth elements. Therefore, by melting these elements together, the specific gravity of the obtained slag can be lowered, and the slag rising speed in the molten metal can be improved. As a result, the slag can be recovered by separating the slag and the molten metal other than the slag in a shorter time.
In the melt preparation step in the rare earth element recovery method of the present invention, the magnetic shielding plate provided in the rotor can be melted together. Since the magnetic shielding plate contains Al as a main component, a part of the added Al is oxidized to become a part of the slag, the specific gravity of the obtained slag can be lowered, and the slag rising speed can be improved. . As a result, it is possible to collect slag in a shorter time.
In the slag generation step in the rare earth element recovery method of the present invention, an oxide containing at least one of Al, Si, Mg, and Ti in addition to oxygen gas and air can be used as the oxidizing substance. In this case, oxygen constituting the oxide is utilized for oxidation of the rare earth element, and the oxidation of the rare earth element can be promoted. Furthermore, the oxide containing at least one of Al, Si, Mg, and Ti can reduce the specific gravity of the slag by being contained in the generated slag. As a result, it is possible to improve the slag ascent rate and collect slag in a shorter time.

  According to the method for reusing steel components of the present invention, the steel components contained in the rare earth magnet motor can be reused. Moreover, the steel components contained in the rotor can be easily recovered from the rotor incorporated in the product and reused as a steel raw material. In particular, a disassembling process for taking out the rare earth magnet constituting the rotor and a demagnetizing process of the rare earth magnet are not required, and a large amount of processing can be performed at low cost. Moreover, in the molten metal preparation process and slag production | generation process in this method, the equipment in the steelmaking technique which has been constructed over a long time can be diverted. Therefore, new capital investment is small and high safety can be secured.

It is explanatory drawing which shows the outline of the collection | recovery method of this rare earth element. It is explanatory drawing which shows the simple structure of a motor.

The present invention will be described in detail below.
[1] Rare Earth Element Recovery Method The rare earth element recovery method of the present invention is a method for recovering a rare earth element from a motor using a rare earth magnet. This method includes a molten metal preparation step (P1), a slag generation step (P2), and a slag recovery step (P3) (see FIG. 1).

The “molten metal preparation step” is a step of obtaining a molten metal by melting the rotor separated from the motor.
The motor (rotary electric machine) used in the present invention has at least a rotor. In addition, a stator (stator) is usually provided. In addition, a housing case for housing the rotor and the stator can be provided. In the molten metal preparation step, the rotor of this motor is melted (dry melting). For example, when the motor includes a storage case, the rotor is taken out from the storage case and used.

Here, the motor will be described (see FIG. 2). As described above, the motor (10) includes the rotor (11), and normally includes the stator (16).
The rotor (11) generally includes a rotating shaft (12) and an iron core (13) that is fixed to the peripheral surface of the rotating shaft (12) and has a substantially circular shape. Furthermore, the iron core (13) is formed by laminating and bonding a plurality of substantially disc-shaped electromagnetic steel plates (14). Moreover, the rare earth magnet (15) is disposed on the outer periphery of the iron core (13) or in the vicinity of the outer periphery of the iron core. More specifically, as described above, when the iron core (13) is composed of the electromagnetic steel plate (14), the rare earth magnet (15) penetrates in the stacking direction of the electromagnetic steel plate (14). It is embedded in the hole using resin.

  Moreover, there is no restriction | limiting in the kind of rare earth magnet utilized with the collection | recovery method of this invention. That is, the rare earth element in the magnet can be recovered regardless of the type of rare earth magnet and the rare earth element contained therein. Examples of rare earth magnets include neodymium magnets (containing Nd, Dy, Tb, etc.), samarium cobalt magnets (containing Sm, etc.) and praseodymium magnets (containing Pr, etc.). In the motor, only one kind of these rare earth magnets may be used, or two or more kinds may be used in combination.

  On the other hand, the stator (16) is formed in an annular shape so as to surround the outer periphery of the rotor (11). Moreover, it arrange | positions through the gap with respect to the outer periphery of a rotor (11). The stator (16) includes a plurality of exciting coils (not shown) so that the rotor (11) can be driven by magnetic force. The exciting coil is usually used by winding a wire made of copper or an alloy containing copper.

  In the melt preparation step of this method, the stator can be dissolved together with the rotor, but it is preferable that the stator is not dissolved. As described above, a wire containing copper is used for the stator. For this reason, when the stator is melted, copper is mixed into the molten metal (copper concentration increases). As will be described later, the remaining molten metal recovered from the rare earth element as slag (hereinafter also simply referred to as “residual hot water”) is useful as a steel raw material. Considering this, it is preferable that the molten metal does not contain copper. This is because there are few steels that require copper as a steel raw material, and even if copper is refined, it is difficult to remove it from the steel raw material, making reuse difficult.

In the melt preparation step, the rotor may be dissolved in any way. For example, the melting furnace is not limited, and an electric furnace, a high frequency induction heating furnace, a ladle type refining furnace, a converter, a blast furnace, and the like can be used. Among these, an electric furnace is preferable from the viewpoint of a high degree of freedom in raw material selection.
Furthermore, the mixing method of the raw material to melt | dissolve in the case of melt | dissolution is not specifically limited. That is, the rotor may be introduced into the furnace and melted directly, or the seed melt may be previously formed in the furnace, and the rotor may be introduced into the seed melt and melted.
When using a seed molten metal, the molten metal which melt | dissolved the iron material can be used for a seed molten metal. The iron material is a material mainly composed of Fe. This iron material will be described in detail in the description of the molten metal preparation process.

  Moreover, when using a seed molten metal, materials other than an iron material can be previously mix | blended in a seed molten metal. Examples of the other material include a material containing at least one of Al, Si, Mg, and Ti. This material may use only 1 type and may use 2 or more types together. This material will be described in detail in the description of the melt preparation process.

  After these materials containing at least one of Al, Si, Mg, and Ti are dissolved, some of them react with oxygen in the atmosphere or oxygen in the molten metal to form oxides, and slag Become part. Oxides composed of these elements have a lower specific gravity than oxides of Nd and Dy, which are the main rare earth elements of rare earth magnets, and as a result, the specific gravity of the generated slag can be lowered. Thereby, the speed at which slag rises from the molten metal can be improved, and slag generation can be completed quickly. That is, the rare earth element can be efficiently recovered. Moreover, by adding these other materials, not only can the slag specific gravity be adjusted as described above, but also the composition of the seed molten metal can be adjusted in accordance with the intended components when reused as a steel raw material.

Furthermore, in the molten metal preparation step, other materials other than the rotor can be melted together if necessary, regardless of whether or not the above-described seed molten metal is used. That is, for example, after the rotor is put into the seed molten metal and dissolved, other materials can be further dissolved. Further, the composition of the molten metal can be adjusted by dissolving only the rotor without using the seed molten metal and then dissolving other materials later.
As described above, as the material other than the rotor that can be used in the molten metal preparation step, an iron material can be used as in the aforementioned seed molten metal.
Specific iron materials include electrolytic iron, pig iron, various iron scraps, and the like. What is necessary is just to select the iron scrap to be used which contains an appropriate component in consideration of which steel type to reuse as a material after melting. Moreover, these iron materials may use only 1 type and may use 2 or more types together.

If the iron material is melted together with the rotor in the molten metal preparation step, the amount of molten metal obtained can be adjusted appropriately. Usually, iron is the largest in the components constituting the entire rotor. This is because each part of the rotor shaft, iron core, rare earth magnet, etc. contains iron. Therefore, even if only the rotor is melted, the remaining hot water after slag recovery contains a lot of iron. However, it is expected that the number of discarded motors fluctuates and is not stable, and if only the rotor is melted, an iron amount sufficient to be reused as a steel raw material may not be obtained thereafter. In such a case, an iron material can be blended in the molten metal preparation step from the viewpoint of reusing the remaining hot water as a steel raw material.
In the molten metal preparation step, the iron material charged into the melting furnace is melted in the furnace and included in the molten metal together with the iron component included in the rotor. And after that, it can be reused as a steel raw material by adjusting to the target component in the same manner as in the production of a normal steel raw material. Thus, in the molten metal preparation process, the iron material can be melted together in order to make it easier to use the remaining hot water after slag recovery as a steel raw material.

  Of course, in the molten metal preparation step, when the iron material is melted together with the rotor, the timing of charging the rotor and the iron material into each melting furnace and the timing of melting them are not particularly limited. . Whatever the form, as a result, the molten metal in which the rotor is melted and the molten metal in which the iron material is melted may be mixed in the melting furnace. Specifically, the iron material may be charged and melted simultaneously with the rotor, or the iron material may be charged into the melting furnace after the rotor is melted. Further, the rotor and the iron material may be interlaced and appropriately input such that the rotor is introduced, then the iron material is introduced, and then the rotor is introduced.

  Furthermore, in the molten metal preparation step, other materials other than the rotor and the iron material can be melted together as necessary regardless of the presence or absence of the iron material. Examples of the other material include a material containing at least one of Al, Si, Mg, and Ti. Specifically, a metal containing at least one of Al, Si, Mg, and Ti, an oxide containing at least one of Al, Si, Mg, and Ti, and Al, Si, Mg, and Ti. Other materials (materials other than metals and oxides) including at least one kind are included. These may use only 1 type and may use 2 or more types together. As described above, these materials lower the specific gravity of the slag.

Among the above materials, examples of the metal include metal aluminum, metal magnesium, metal titanium, an alloy including at least one of Al, Si, Mg, and Ti. Examples of the alloy include an aluminum alloy, a magnesium alloy, a titanium alloy, an Al—Mg—Si alloy, ferroaluminum, ferrosilicon, ferromagnesium, and ferrotitanium. These may use only 1 type and may use 2 or more types together.
In addition, among the above materials, the oxide includes aluminum oxide (alumina), silicon oxide, magnesium oxide (magnesia), titanium oxide (titania), and a composite containing at least one of Al, Si, Mg, and Ti. An oxide etc. are mentioned. These may use only 1 type and may use 2 or more types together.

Furthermore, examples of the material mainly composed of silicon oxide among oxides include various minerals and glass containing silicon oxide. Glass can be used regardless of its type, and waste glass is particularly preferable. Waste glass is preferable because it usually contains Si and Al. Glass is an amorphous material and has a low melting point so that it can be easily dissolved. For this reason, the energy cost required for dissolution can be kept low. As this waste glass, waste glass for automobiles can be used. Waste glass for automotive use includes automotive glass produced by scrap processing of automobiles. For example, a windshield, rear glass, side glass, lamp glass, and the like. Such automotive waste glass often contains resin parts and metal parts other than glass, but in the rare earth element recovery method of the present invention, as described above, as an auxiliary agent for reducing the specific gravity of slag. Functioned.
Furthermore, as a material containing at least one of Al, Si, Mg, and Ti and other than the metal and oxide, simple silicon, calcium silicide, manganese silicide, and the like can be given. These materials may use only 1 type and may use 2 or more types together.

  Of course, in the molten metal preparation process, when melting a material containing at least one of Al, Si, Mg and Ti together with the rotor, the rotor and the material are charged into each melting furnace. There are no particular restrictions on the timing to be performed and the timing at which they are dissolved. Whatever form, as a result, the molten metal in which the rotor is melted and the molten metal in which the material is melted may be mixed in the melting furnace. Specifically, the material may be charged and melted simultaneously with the rotor, or the material may be charged into a melting furnace after the rotor is melted. Further, the rotor and the material may be interlaced so that the material is charged after the rotor is charged and then the rotor is further charged.

  In addition, in the molten metal preparation step, a rotor and these iron materials and materials other than the above-described materials may be used as necessary, regardless of the presence or absence of the iron material and a material containing at least one of Al, Si, Mg, and Ti. Other materials can be dissolved together. Another material is a magnetic shielding plate. The magnetic shielding plate is a plate used for shielding magnetism. Further, the magnetic shielding plate is usually made of a metal containing Al. That is, it is a plate made of aluminum or aluminum alloy. For this reason, when a magnetic shielding plate is blended in the molten metal preparation step, Al (aluminum) can be added into the molten metal. As described above, Al is oxidized in the slag generation step, and a part thereof becomes an oxide and is contained in the slag. Thereby, the specific gravity of the produced | generated slag can be lowered | hung.

  Any magnetic shielding plate may be used as the magnetic shielding plate. For example, a magnetic shielding plate included in the motor or a magnetic shielding plate disposed outside the motor may be used. Among these, a magnetic shielding plate disposed in the motor, and more preferably a magnetic shielding plate provided in the rotor. The magnetic shielding plates provided in the rotor are, for example, disposed on both sides of the iron core to form a substantially disk-shaped plate. Since the magnetic shielding plate provided in the rotor is provided integrally with the rotor, it can be charged together with the rotor and dissolved. That is, if the rotor provided with the magnetic shielding plate is melted, the slag flying speed in the slag generation process can be improved. As a matter of course, the magnetic shielding plate can be separated from the rotor, and an appropriate amount can be added as necessary.

  The “slag generation step” is a step of generating slag containing rare earth oxide by introducing an oxidizing substance into the obtained molten metal. By introducing an oxidizing substance into the molten metal, the rare earth elements dissolved and contained in the molten metal can be oxidized and floated on the molten metal as slag. In this slag generation process, the oxidation process and its equipment in steel refining can be used as they are. That is, the above-described molten metal preparation process can use the equipment for refining steelmaking as it is, and therefore does not require special equipment for collecting rare earth elements. Therefore, it is possible to recover rare earth elements with extremely excellent cost merit. In other words, a rare earth element recovery method can be performed as part of the steel refining process.

  As the oxidizing substance used in this step, for example, oxygen can be used. Oxygen may be used in any form. That is, for example, oxygen gas (pure oxygen gas) can be introduced into the melting furnace or molten metal. Moreover, it can introduce | transduce into a melting furnace or a molten metal as mixed gas containing other gas with oxygen. Examples of the mixed gas include air, a mixed gas of oxygen and inert gas, a mixed gas of oxygen and nitrogen, and the like.

  Furthermore, as the oxidizing substance used in the slag generation step, an oxide containing at least one of Al, Si, Mg, and Ti in addition to oxygen can be used. As such an oxide, an oxide containing at least one of Al, Si, Mg, and Ti described in the explanation of the molten metal preparation step can be used as it is. In addition, this oxide may mix | blend in both a molten metal preparation process and a slag production | generation process, and may mix | blend only in any one process.

  As the oxide used in the slag generation step, as described above, aluminum oxide (alumina), silicon oxide, magnesium oxide (magnesia), titanium oxide (titania), and at least one of Al, Si, Mg, and Ti Examples include complex oxides containing seeds. These may use only 1 type and may use 2 or more types together. Further, the material mainly composed of silicon oxide is as described above.

  The “slag recovery step” is a step of recovering the generated slag. In this step, slag may be collected in any way. That is, the slag can be taken out of the melting furnace and recovered. Further, the molten metal may be discharged from the melting furnace (steeling), and the slag may be left in the melting furnace and recovered.

In the rare earth element recovery method of the present invention, the rare earth element can be concentrated by a refining step of refining slag and concentrating the rare earth element after the melt preparation step and the slag generation step.
In this refining process, any method may be used to concentrate the rare earth element. That is, examples of the refining method that can be used in the smelting step include solvent extraction, dissolved salt electrolysis, ion exchange, fractional crystallization, and fractional precipitation. These methods may use only 1 type and may use 2 or more types together. Among these, the solvent extraction method is preferable because it can be operated continuously.

  In the case of using the solvent extraction method, various conventionally used extraction solvents and apparatuses therefor can be appropriately used. That is, examples of the extraction solvent include a cation exchange extraction solvent, a solvation extraction solvent, and an anion exchange extraction solvent. These may use only 1 type and may use 2 or more types together. Examples of the extraction device include a mixer settler, a spray column, a pulse column, and a centrifugal extractor. These may use only 1 type and may use 2 or more types together.

Unlike the case of obtaining rare earth ore, the slag obtained by the method for recovering rare earth elements of the present invention does not require beneficiation. Ores with high rare earth element content such as monazite (xenotime), vanestite, and symbiotic ore (rare earth ore) are selected from ordinary ores by selecting the raw ore. On the other hand, the slag obtained by the present method can contain a rare earth element having a high concentration equal to or higher than the rare earth ore after the beneficiation. For this reason, it is not necessary to perform beneficiation.
Further, since it is the same oxide as the rare earth ore, the rare earth element can be extracted and refined using the same technique as the refining of the rare earth ore.
Furthermore, since many rare earth ores contain radioactive substances such as thorium, it is necessary to concentrate and remove thorium as a pyrophosphate compound or the like during the refining of rare earth ores. On the other hand, the slag obtained by this method does not contain radioactive materials such as thorium. For this reason, the process of concentrating and removing the radioactive substance as described above is not required.
Thus, refining for obtaining a rare earth element from slag obtained by the present method can be performed more easily and at a lower cost than refining for obtaining a rare earth element from ore.

[2] Method for Reusing Steel Components The method for reusing steel components according to the present invention is a method for reusing steel components contained in motors using rare earth magnets as raw materials for steel. In this recycling method, after the slag recovery step in the rare earth element recovery method, the remaining molten metal from which the slag has been recovered is used as a steel raw material. The obtained molten metal can be further made into a steel raw material suitable for various uses by adjusting the components by a method such as adding alloy iron and performing refining such as degassing. Especially, in the said rare earth element collection | recovery method, the rotor with which the electromagnetic steel plate was utilized is utilized as a molten metal raw material. For this reason, generally a molten metal with high content of Si and B can be obtained. Therefore, in this recycling method, the steel component contained in the rare earth magnet motor can be suitably used as a steel raw material for high Si steel (ie, high Si spring steel, electromagnetic steel plate, etc.). Moreover, it can utilize suitably as a steel raw material for B addition steel.

Hereinafter, the present invention will be specifically described by way of examples.
<Example 1> Example using a rotor with a magnetic shielding plate (1) Molten metal preparation process A rotor (with magnetic shielding plate) and electrolytic iron are put into a crucible, and high frequency induction heating is performed. went. After visually confirming that both the rotor and the electrolytic iron were dissolved, heating was stopped.
Here, the rotor used in the first embodiment is a rotor taken out from the wheel driving motor of the hybrid vehicle. The rotor includes a rotating shaft and an iron core fixed to the peripheral surface thereof. A rare earth magnet is disposed on the iron core. Furthermore, magnetic shielding plates made of aluminum alloy are disposed on both sides of the iron core of the rotor. In Example 1, the magnetic shielding plate was also used with the rotor (the magnetic shielding plate was used without being separated).

(2) Slag production | generation process After stopping heating in said (1), introduction | transduction of oxygen gas was started to the molten metal produced | generated in the crucible. The introduction of oxygen gas was performed for about 10 minutes. Thereafter, the mixture was left for 5 minutes in order to secure a time for the oxidation reaction to be in an equilibrium state.

(3) Slag collection process After said (2), the crucible was inclined and the molten metal (that is, steel raw material) was discharged | emitted by casting a molten metal in a casting_mold | template. As a result, slag remained in the crucible, and the slag was recovered by recovering the remaining slag.

<Example 2> Example using a rotor from which a magnetic shielding plate was separated (1) Melt preparation step The same procedure as in the melt preparation step in Example 1 was performed. However, the used rotor is different from the first embodiment in that the magnetic shielding plate is separated.
(2) Slag production | generation process After stopping heating in said (1), introduction | transduction of oxygen gas was started to the molten metal produced | generated in the crucible. The introduction of oxygen gas and the subsequent standing were performed in the same manner as in Example 1.
(3) Slag recovery process Slag recovery was performed in the same manner as the slag recovery process in Example 1. At the same time, a steel ingot as a steel raw material was obtained.

<Comparative example 1> Example which does not perform a slag production | generation process (1) Molten metal preparation process It carried out similarly to the molten metal preparation process in Example 1. FIG. That is, a rotor with a magnetic shielding plate was used.
(2) Molten metal recovery Oxygen gas was not introduced to generate slag, and other oxidizing substances were not introduced, and the molten metal produced in the crucible was cast into the mold to discharge the molten metal. .

[2] Evaluation of slag and steel raw material (1) Component analysis of slag Samples for evaluation were collected from three different points in the slag collected in Example 1. Component analysis of the obtained sample for evaluation was performed using an ICP emission spectrometer (manufactured by Shimadzu Corporation, model “ICPS-8100”). The results are shown in Table 1.
The slag collected in Example 2 was also subjected to slag component analysis in the same manner as in Example 1 above. The results are also shown in Table 1.

(2) Component analysis of steel raw material In Example 1, samples for evaluation were collected from two different points in a steel ingot (steel raw material) obtained by casting molten metal into a mold. The component analysis of the obtained sample for evaluation was performed in the same manner as the component analysis of the slag. The results are shown in Table 2.
For the steel ingot (steel raw material) collected in Example 2, component analysis was performed in the same manner as in Example 1 above. The results are also shown in Table 2.
Further, the steel ingot collected in Comparative Example 1 was also subjected to component analysis of the steel ingot in the same manner as in Example 1. The results are also shown in Table 2.

尚、表１中の「＜０．１」は、０．１質量％未満であることを表す。

In Table 1, “<0.1” represents less than 0.1% by mass.

尚、表２中の「＜０．１」は、０．１質量％未満であることを表す。

In Table 2, “<0.1” represents less than 0.1% by mass.

[3] Effects of Examples From the results of Tables 1 and 2, the slags of Examples 1 and 2 contain high concentrations of Nd (neodymium) and Dy (dysprosium), It can be seen that the steel ingots obtained in the same example contain at most 0.1% by mass of Nd and less than 0.1% by mass of Dy. That is, it can be seen that the rare earth element is efficiently transferred to the slag and hardly remains in the steel ingot. From this result, it is understood that the rare earth element can be efficiently recovered by the recovery method of the present invention.

Sample 1 of Experimental Example 1 contained a total of 64.6% by mass of rare earth elements with respect to the entire sample (100% by mass). Similarly, it is 31.1 mass% in the sample 2 of the experimental example 1, and 48.9 mass% in the sample 3 of the experimental example 1. That is, the average value of the rare earth elements contained in the slag of Example 1 was 48.2% by mass. Sample 1 of Experimental Example 2 contained a total of 53.4% by mass of rare earth elements with respect to 100% by mass of the entire sample. Similarly, it is 50.3% by mass for Sample 2 of Experimental Example 2, and 21.7% by mass for Sample 3 of Experimental Example 2. That is, the average value of the rare earth elements contained in the slag of Example 2 was 41.8% by mass. In general, it can be seen that the rare earth element content in the slag obtained by the present method is extremely high considering that the rare earth element content in the rare earth ore after the beneficiation is about several mass%.
On the other hand, since the comparative example 1 only melt | dissolved the rotor as it is, it turns out that a rare earth element will be in the state contained in the steel ingot obtained by solidifying a molten metal naturally.

  In Example 1, the magnetic shielding plate was dissolved together with the rotor, whereas in Example 2, the magnetic shielding plate was not dissolved. In order to confirm the influence of this difference, a portion of the molten steel (molten metal) was sampled and solidified after 7 minutes from the start of oxygen gas introduction, and then cut. And the oxide distribution condition of the obtained cut surface was investigated by EDS analysis of a scanning electron microscope. As a result, Nd and Dy oxides could not be confirmed in Example 1. On the other hand, in Example 2, the presence of a slight amount of oxides of Nd and Dy was recognized. From this result, it was confirmed that Example 1 can float the rare earth element oxide in a shorter time and complete the slag generation step.

  This is because the Al contained in the magnetic shielding plate is oxidized and contained in the slag, so that the slag is generated in which the ratio of the Al oxide having a smaller specific gravity than the oxide of Nd and Dy is generated. This is thought to be because the specific gravity of the generated slag decreased and the slag ascent increased. From this, it can be seen that it is preferable to dissolve together with the rotor a material containing a component capable of forming an oxide having a specific gravity smaller than that of iron, such as a magnetic shielding plate. Thereby, recovery of rare earth elements can be performed efficiently in a shorter time.

  Furthermore, from the results in Table 2, it can be seen that the steel ingots obtained in Example 1 and Example 2 are both excellent steel raw materials with high iron purity. Moreover, 0.9-1.0 mass% silicon was contained in the steel ingot obtained especially. From this, it is suitable as a steel raw material for producing a material having a high silicon content such as high Si spring steel and electromagnetic steel sheet.

  In addition, in this invention, it can restrict to what is shown to said specific Example, It can be set as the Example variously changed within the range of this invention according to the objective and the use. That is, for example, the motor is not limited to the above-described motor for driving the wheel of a hybrid vehicle, and can naturally be applied similarly to the motor for driving a wheel of an electric vehicle. Further, not only these driving motors, but also, for example, power generation motors used for other purposes such as wind power generation, can be similarly applied as long as the motors use rare earth magnets.

DESCRIPTION OF SYMBOLS 1; Rotor, 2; Molten metal, 3; Slag (slag containing rare earth elements), 4; Oxygen gas (oxidizing substance), 5; Remaining hot water, 6; Melting furnace, 7; Oxygen gas (oxidizing substance) introduction mouth,
DESCRIPTION OF SYMBOLS 10; Motor, 11; Rotor, 12: Rotating shaft, 13: Iron core, 14: Electrical steel plate, 15: Rare earth magnet, 16: Stator.

Claims (8)

A method of recovering rare earth elements from a motor using rare earth magnets,
Melting the rotor separated from the motor to obtain a molten metal,
Introducing an oxidizing substance into the resulting molten metal to produce a slag containing rare earth oxides,
A slag recovery step of recovering the slag, and a method for recovering a rare earth element.   The method for recovering a rare earth element according to claim 1, wherein in the molten metal preparation step, the iron material is also melted.   The method for recovering a rare earth element according to claim 1 or 2, wherein in the molten metal preparation step, a material containing at least one of Al, Si, Mg, and Ti is melted together.   The method for recovering a rare earth element according to any one of claims 1 to 3, wherein in the molten metal preparation step, a magnetic shielding plate provided in the rotor is melted together.   5. The rare earth element recovery method according to claim 1, wherein oxygen is used as the oxidizing substance in the slag generation step.   The method for recovering a rare earth element according to any one of claims 1 to 5, wherein in the slag generation step, an oxide containing at least one of Al, Si, Mg, and Ti is used as the oxidizing substance.   The method for recovering a rare earth element according to any one of claims 1 to 6, further comprising a refining step of refining the slag and concentrating the rare earth element.   The slag is recovered in the slag recovery step in the rare earth element recovery method according to any one of claims 1 to 7, and the remaining molten metal is reused as a steel material. Reuse method of steel components.

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