KR102153737B1 - Method of recovery rare earth elements from a ferrite-rare earth-based permanent magnet using selective chlorination - Google Patents

Abstract

According to the present invention, provided is a method for recovering rare-earth elements from an iron-rare earth-based permanent magnet using a selective chlorination method, which includes the following steps of: (S100) crushing the permanent magnet; (S200) mixing the permanent magnet and zinc chloride; (S300) selectively chloridizing the rare-earth elements; and (S400) separating rare-earth chloride. According to the present invention, the method for recovering rare-earth elements from an iron-rare earth-based permanent magnet using the selective chlorination method can recover the rare-earth elements from the waste permanent magnet containing the rare-earth elements in a simple and economic extraction process with high extraction efficiency and have a dry process to be less burdened with environmental issues.

Description

[METHOD OF RECOVERY RARE EARTH ELEMENTS FROM A FERRITE-RARE EARTH-BASED PERMANENT MAGNET USING SELECTIVE CHLORINATION}

The present invention relates to a method for recovering rare earth elements from an iron-rare earth permanent magnet by a selective chlorination method.

Permanent magnets have been started in recent rapid progress and have been applied to various fields, and their performance has been improved and new devices are being developed day by day. In particular, from the viewpoint of energy saving and environmental measures, the spread to IT, automobiles, home appliances, FA fields, etc. is rapidly expanding.

Neodymium magnets are permanent magnets mainly composed of a neodymium-iron-boron (Nd-Fe-B) intermetallic compound (Nd ₂ Fe ₁₄ B). Neodymium magnets have advantages such as excellent magnetic properties, high strength, and low production cost, and are applied to various industrial products, and the production volume is increasing exponentially. The main uses of neodymium (Nd) magnets include voice coil motors for hard disks, air conditioner compressor motors, and hybrid vehicle motors. In addition, since high coercivity is required at high temperatures for compressors of air conditioners and hybrid vehicles, neodymium magnets added with dysprosium (Dy) are used to increase coercivity. With the spread of hybrid vehicles in the future, the consumption of neodymium magnets with dysprosium (Dy) added significantly increases, and a large amount of magnetic scrap is expected to occur in the future.

On the other hand, rare earth elements such as neodymium (Nd) and dysprosium (Dy), which are raw materials for neodymium magnets, have excellent deposits ubiquitous in certain countries, and their prices are liable to fluctuate due to export regulations of the respective countries, and thus provide a stable supply. Anxiety is rising. In addition, since rare earth ores contain radioactive elements such as uranium (U) and thorium (Th), environmental destruction due to mining and treatment of radioactive materials that are concentrated during rare earth refining are serious problems.

As for dysprosium (Dy), there are ion adsorption-type deposits that contain almost no radioactive elements, but these deposits are rare geologically, and during mining and extraction, they destroy the environment in order to inject acid directly into the soil. .

In addition, since neodymium (Nd) is relatively abundant as a resource, there is less concern about depletion, but if it is produced from ore, the treatment of radioactive elements is inevitable. Given the environmental destruction caused by the mining and smelting of ore and the increasing demand for neodymium magnets in the future, the recovery of rare earth elements from product scrap is an important task. However, currently, rare earth elements are rarely recycled in products except for large-sized MRI magnets.

Patent Document 1 discloses a method of recycling a neodymium magnet by reacting an iron chloride with rare earth magnet scrap or magnetic sludge (magnet cutting material) and recovering the rare earth element as chloride. The method of the above document is to separate and recover rare earth element chloride from iron chloride by heating a mixture of solid iron chloride, activated carbon and magnetic sludge, followed by distillation. Neodymium oxidized with Nd ₂ O ₃ is also converted to chloride. It is characterized in that it can be separated and recovered efficiently, and the chemical reaction is carried out in a region where the partial pressure of chlorine is high under a carbon reduction atmosphere, so that only iron chloride (FeCl ₂ ) with high reducibility can be used as the chlorinating agent. .

In Patent Document 2, as a method of separating neodymium from neodymium magnets by selective chlorination, rare earth magnet scraps are reacted with metal chlorides or metal iodides such as MgCl ₂ and ZnI ₂ at 1000°C (1273K) to selectively halide only rare earths. It is possible to do so, and it is disclosed that rare earths can be selectively extracted thereby. The document proposes that CuCl _x , FeCl _x , ZnCl _x and the like can be used as a chlorinating agent when the rare earth element and iron are simultaneously included, but specific examples are not described.

Non-Patent Document 1 discloses a method of separating neodymium from a neodymium magnet by selective chlorination, using hydrogen chloride generated by thermal decomposition of PVC as a chlorinating agent.

According to the techniques described in Patent Documents 1 and 2 and Non-Patent Document 1, it is possible to recover rare earth elements such as Nd, Dy and/or Pr from neodymium magnets and magnetic sludge, but is applied to the separation and recovery of various other rare earth elements. It is unclear if it can be done, and the technology to recover rare earth elements such as neodymium from large magnet scraps used in high-power motors for automobiles, which is expected to increase in quantity in the future, with high selectivity and efficiency is also an important social issue.

Accordingly, there is a need to develop a method for recovering rare earth elements that can simplify the extraction process of rare earth elements in the iron-rare earth permanent magnet, lower the extraction cost, and increase extraction efficiency.

Japanese Patent Publication 2003-073754 (published on March 12, 2003) International Publication WO2009119720 (published on October 1, 2009)

J. of Korean Inst. of Resources Recycling, Vol. 27, No. 1, 2018, 38 (published on February 28, 2018)

An object of the present invention is to provide a method for recovering rare earth elements, which can simplify the extraction process of rare earth elements in an iron-rare earth permanent magnet, lower the extraction cost, and increase extraction efficiency.

The problem to be solved by the present invention is not limited to the problem(s) mentioned above, and another problem(s) that is not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above object, the present invention

(Step 1) pulverizing an iron-rare earth-based permanent magnet, a permanent magnet crushing step;

(Step 2) mixing the iron-rare earth-based permanent magnet pulverized product and zinc chloride obtained in Step 1, mixing the permanent magnet and zinc chloride;

(Step 3) Selective chlorination of rare earths, selectively chlorinating rare earths in the obtained mixture; And

(Step 4) separating the obtained rare earth chloride, a step of separating the rare earth chloride;

It provides a method for recovering rare earth elements by selective chlorination from iron-rare earth permanent magnets comprising a.

According to an embodiment of the present invention, in step 1, the iron-rare earth-based permanent magnet may be a neodymium-iron-boron (Nd-Fe-B)-based permanent magnet.

According to an embodiment of the present invention, in step 1, the iron-rare earth permanent magnet may be a waste permanent magnet scrap or a permanent magnet sludge.

According to an embodiment of the present invention, in step 1, the iron-rare earth permanent magnet may be pulverized to a particle size of 75 μm to 2 mm, preferably 300 μm to 600 μm.

According to an embodiment of the present invention, in step 1, the iron-rare earth permanent magnet may be pulverized to a particle size of 300 μm to 600 μm.

According to an embodiment of the present invention, in the step 2, the iron-rare earth-based permanent magnet pulverized product and zinc chloride are mixed in a weight ratio of 1:0.4 to 1:3.0, preferably 1:1.8 to 1:2.7. I can.

According to an embodiment of the present invention, in step 2, the iron-rare earth permanent magnet pulverized product and zinc chloride may be mixed in a weight ratio of 1:1.8 to 1:2.7.

According to an embodiment of the present invention, in step 3, the permanent magnet pulverized product and the zinc chloride mixture may be selectively chlorinated by heating at a temperature of 600K or more, preferably 800K or more, and specifically 900 to 1000K.

According to an embodiment of the present invention, in step 3, the pulverized permanent magnet and the zinc chloride mixture may be heated to a temperature of 900 to 1000 K for selective chlorination.

According to an embodiment of the present invention, in step 3, the mixture may be heated for 1 to 5 hours, preferably 1.5 to 2.5 hours.

According to an embodiment of the present invention, in step 3, the molten mixture may be heated for 1.5 to 2.5 hours.

According to an embodiment of the present invention, in step 4, the rare earth element chloride may be separated by vacuum distillation.

According to an embodiment of the present invention, in step 4, the vacuum distillation may be performed by heating at a temperature of 1000 to 1300 K at a pressure of 1x10 ^-2 to 1x10 ^-5 atm.

According to an embodiment of the present invention, in step 4, the vacuum distillation may be performed by heating at a temperature of 1100 to 1200K at a pressure of 1x10 ^-3 to 1x10 ^-4 atm.

According to an embodiment of the present invention, a mixture of rare earth chlorides may be provided by the recovery method.

According to an embodiment of the present invention, a mixture of rare earth chlorides, including neodymium (Nd) chloride or dysprosium (Dy) chloride, may be provided.

According to the present invention, neodymium (Nd) chloride and/or dysprosium (Dy) chloride can be recovered from a waste permanent magnet containing a rare earth element with high extraction efficiency and a simple and economical extraction process. The burden is small.

The effects of the present invention are not limited to the above effects, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a process flow chart according to an embodiment of a method for recovering rare earth elements of the present invention.
2A and 2B are XRD analysis graphs of samples before the selective chlorination reaction and products (unseparated) after the selective chlorination reaction in Example 1 of the present invention. By the selective chlorination reaction, iron is present as Fe metal and neodymium is NdCl ₃ You can confirm that it exists.
3 is a graph showing a change in vapor pressure according to the temperature of a metal chloride.
4A, 4B and 4C show thermodynamic analysis diagrams of the selective chlorination of metals neodymium (Nd), dysprosium (Dy) and iron (Fe) using zinc chloride.
5 is a schematic diagram showing an example of an apparatus for carrying out a conventional method for recovering rare earth elements by selective chlorination using magnesium chloride as a chlorinating agent.
6 is a schematic diagram showing an example of an apparatus for carrying out the method for recovering rare earth elements by selective chlorination according to the present invention.

Before describing the present invention in detail, terms and words used in the present specification are not to be interpreted as being unconditionally limited to their usual or dictionary meanings, and in order for the inventors of the present invention to describe their invention in the best way It should be understood that the concepts of various terms can be appropriately defined and used, and furthermore, these terms or words should be interpreted as meanings and concepts consistent with the technical idea of the present invention.

That is, the terms used in this specification are only used to describe a preferred embodiment of the present invention, and are not intended to specifically limit the content of the present invention, and these terms are used to describe various possibilities of the present invention. It should be noted that this is a term defined in consideration.

In addition, in this specification, it should be understood that the singular expression may include a plural expression unless clearly indicated in a different meaning in the context, and even if similarly expressed in the plural, the singular expression may include the meaning of the singular number. do.

Throughout the present specification, when a component is described as "including" another component, it does not exclude any other component, but further includes any other component unless otherwise indicated. It could mean you can do it.

Further, in the following description of the present invention, a detailed description of a configuration that is determined to unnecessarily obscure the subject matter of the present invention, for example, a known technology including the prior art may be omitted.

The first object of the present invention is to provide a method for recovering rare earth elements by selective chlorination from iron-rare earth permanent magnets, comprising the following steps:

(Step 1) pulverizing an iron-rare earth-based permanent magnet, a permanent magnet crushing step;

(Step 2) mixing the iron-rare earth-based permanent magnet pulverized product and zinc chloride obtained in Step 1, mixing the permanent magnet and zinc chloride;

(Step 3) Selective chlorination of rare earths, selectively chlorinating rare earths in the obtained mixture; And

(Step 4) Separating the rare earth chloride obtained by separating the rare earth chloride.

1 is a process flow chart according to an embodiment of the above-described method for recovering rare earth elements, wherein steps S100 to S400 correspond to steps 1 to 4, respectively:

(S100) permanent magnet grinding step;

(S200) mixing a permanent magnet and zinc chloride;

(S300) selective chlorination of rare earths; And

(S400) Separation step of rare earth chloride.

In step S100 (step 1) of the present invention, the iron-rare earth permanent magnet may be pulverized into, for example, a particle size of 100 μm to 2 mm, preferably 300 μm to 600 μm.

The iron-rare earth-based permanent magnet may generally be a neodymium-iron-boron (Nd-Fe-B)-based permanent magnet, and the present invention is an iron-rare earth-based waste permanent magnet scrap or iron-rare-earth-based permanent magnet sludge. Can be applied to recover.

In step S200 (step 2) of the present invention, the iron-rare earth-based permanent magnet pulverized product obtained in S100 is added to zinc chloride in a weight ratio of 1:0.4 to 1:3.0, preferably 1:1.8 to 1:2.7. You can mix. If the mixing ratio exceeds the above-described range, there is a problem that zinc chloride is used excessively, and if it is less than the above-described range, there is a problem of chlorination reaction of rare earths in the permanent magnet.

In the present invention, the zinc chloride may be in a solid state or a molten state. Zinc chloride is heated to a melting point (586K) or higher, preferably 600K, more preferably 600 to 800K to form a melt, and the above-described pulverized permanent magnet may be added to form a mixture.

In step S300 (step 3) of the present invention, a mixture of the pulverized permanent magnet and zinc chloride is, for example, 600 K or higher, preferably 800 K or higher, specifically at a temperature of 900 to 1000 K, 1 to 5 The rare earth can be selectively chlorinated by heating for an hour, preferably 1.5 to 2.5 hours.

If the reaction temperature in step S300 is lower than 800K, there is a concern that chlorination does not occur sufficiently or it takes a long time for chlorination, and if it is higher than 1000K, energy consumption increases and zinc chloride is rapidly evaporated, so that chlorination may not be sufficient.

Since zinc chloride has a boiling point of about 732℃ (1005K), the pulverized permanent magnet reacts with zinc chloride in liquid and gaseous form when chlorinating with zinc chloride, and as time increases, unreacted zinc chloride evaporates, resulting in rare earth chloride and iron. It can be easily separated from zinc chloride used as chlorinating agent.

Since zinc chloride has a boiling point of about 732℃ (1005K), the pulverized permanent magnet reacts with zinc chloride in liquid and gaseous form when chlorinating with zinc chloride, and as time increases, the unreacted zinc chloride evaporates, resulting in rare earth chloride and iron. It can be easily separated from zinc chloride used as chlorinating agent.

In addition, if the reaction time in step S300 is less than the above range, there is a concern that the chlorination reaction may not proceed sufficiently, and if the above range is exceeded, energy consumption increases, and the zinc chloride used as the chlorinating agent rapidly evaporates, and the chlorination reaction does not proceed sufficiently. There is concern.

In step S400 (step 4) of the present invention, the rare earth chloride obtained by selective chlorination in step S300 may be separated by, for example, vacuum distillation. The vacuum distillation may be performed by heating at a temperature of 1000 to 1300K at a pressure of 1x10 ^-2 to 1x10 ^-5 atm, preferably heating to a temperature of 1100 to 1200K at a pressure of 1x10 ^-3 to 1x10 ^-4 atm. .

In the present invention, rare earth chlorides (NdCl ₃ , DyCl ₃ ) and metallic iron (Fe), which are products of a selective chlorination reaction, have a very large difference in boiling point or vapor pressure, and thus can be easily separated by vacuum distillation. 3 is a graph showing the change in vapor pressure according to the temperature of various metal chlorides, and rare earth chlorides (NdCl ₃ , DyCl ₃ ) are other metal chlorides (eg ZnCl ₂ , FeCl ₂ , and others) present in the above-described selective chlorination system. FeCl _3, etc.) and vapor pressure are sufficient.

According to an embodiment of the present invention, a mixture of rare earth chlorides may be obtained by the method of recovering rare earth elements by selective chlorination from the iron-rare earth permanent magnet described above. The rare earth chloride may include neodymium (Nd) chloride or dysprosium (Dy) chloride.

According to another embodiment of the present invention, the steps S200 and S300 may not be performed sequentially, but may be performed simultaneously or together. Specifically, zinc chloride is heated to a temperature of 800 K or higher to form a melt, and the above-described permanent magnet pulverized product is partially or continuously added and mixed, thereby performing steps S200 and S300 together.

In the present invention, a method of recovering rare earth elements by a selective chlorination method can be theoretically supported through a thermodynamic analysis diagram.

For example, FIG. 4A is a chemical potential diagram obtained by thermodynamically analyzing the selective chlorination reaction of metal neodymium (Nd) using zinc chloride, and FIG. 4B is a thermodynamic view of the selective chlorination reaction of metal dysprosium (Dy) using zinc chloride. It is a chemical potential diagram obtained by analysis by, and FIG. 4C is a chemical potential diagram obtained by thermodynamic analysis of the selective chlorination reaction of metallic iron (Fe) using zinc chloride.

4A is a diagram of a thermodynamic analysis at 1000K of an Nd-Zn-Cl ternary component system, where at point a, neodymium chloride (NdCl ₃ ), zinc chloride (ZnCl ₂ ), and metallic zinc (Zn) are in equilibrium. This means that when neodymium and zinc chloride react at a temperature of 1000K, neodymium is converted to neodymium chloride and at the same time metallic zinc is produced as a reaction product.

Figure 4b is a diagram of a thermodynamic analysis at 1000K of a Dy-Zn-Cl ternary system, similar to neodymium, at point b, dysprosium chloride (DyCl ₃ ), zinc chloride (ZnCl ₂ ), and metallic zinc (Zn) equilibrate. Is being achieved. Therefore, dysprosium (Dy) and zinc chloride (ZnCl ₂ ) can be converted into dysprosium chloride (DyCl ₃ ) and metallic zinc (Zn) by selectively performing a chlorination reaction at a temperature of 1000 K.

On the other hand, Figure 4c is a thermodynamic analysis diagram at 1000K of the Fe-Zn-Cl ternary system, unlike the Nd-Zn-Cl ternary system and the Dy-Zn-Cl ternary system, iron chloride (FeCl ₂ and FeCl ₃ ), There is no point in which zinc chloride (ZnCl ₂ ) and metallic zinc (Zn) are in equilibrium. This means that in the case of iron (Fe), it is difficult to generate iron chloride by reacting with zinc chloride (ZnCl ₂ ) at 1000K.

5 is a schematic diagram showing an example of an apparatus for carrying out a conventional method for recovering rare earth elements by selective chlorination using magnesium chloride as a chlorinating agent.

6 is a schematic diagram showing an example of an apparatus for carrying out the method for recovering rare earth elements by selective chlorination according to the present invention.

Hereinafter, the present invention will be described in more detail through examples. However, the following examples are for explaining the present invention more specifically, and the scope of the present invention is not limited by the following examples. The following examples can be appropriately modified and changed by those skilled in the art within the scope of the present invention.

Example

Example 1

Neodymium-based waste permanent magnets (20.7% Nd, 3.71% Dy, 6.62% Pr, 67.9% Fe) were pulverized to a particle size of 75 μm to 600 μm.

Neodymium-based waste permanent magnet pulverized product and anhydrous zinc chloride (ZnCl ₂ ) were mixed in a weight ratio of 1:2.72 in an alumina crucible under an argon gas atmosphere, and a graphite plate was placed on the alumina crucible and placed in a quartz holder.

After charging the quartz holder into the quartz reaction tube, the atmosphere in the reaction tube was replaced with argon gas, and then charged into an electric furnace heated to 1000K and reacted for 1.5-5 hours.

After the reaction was completed, the quartz reaction tube was taken out of the electric furnace and cooled in the atmosphere. The samples for measuring the chlorination rate of rare earth elements show that rare earth elements and rare earth oxides are not soluble in water, but rare earth chlorides are easily soluble in water. The product was recovered by leaching in ultrapure water for 30 minutes and then drying at 343K for 30 minutes.

2A and 2B are graphs of XRD analysis of a sample before a selective chlorination reaction and a product (unseparated) after a selective chlorination reaction in Example 1 of the present invention.

Specifically, Figures 2a and 2b are graphs showing the XRD analysis results of the neodymium-based permanent magnet used as a sample in Example 1 of the present invention, and Figure 2b is a selective chlorination reaction using zinc chloride in Example 1 using ultrapure water. It is a graph showing the XRD analysis results of the recovered product without post-treatment. In Figure 2b, it can be seen that iron is present as Fe metal and neodymium is present as NdCl ₃ by a selective chlorination reaction.

Example 2

The selective chlorination reaction was carried out in the same manner as in Example 1, except that the experimental conditions described in Table 2 were performed, and the results are shown in Table 2 below.

In the above examples, the chlorination rate or recovery rate r of rare earth elements such as neodymium was calculated according to the following calculation formula 1:

[Calculation 1]

R(%) = 100 × (1- M _{REE in residue} / M _{REE in feed} )

In Formula 1, M _{REE in residue} represents the weight of the rare earth element in the sample recovered after selective salting, and M _{REE in feed} represents the weight of the rare earth element in the permanent magnet.

The extraction rate of neodymium calculated according to Equation 1 was 93.8-96.5%, which was higher than the extraction rate (approximately 80%) of the conventional selective chlorination method using MgCl ₂ , as well as excellent energy efficiency because it proceeds at a low temperature. . In addition, it was demonstrated that not only neodymium and dysprosium but also praseodymium can be extracted by chlorination.

Until now, specific examples of a method for recovering rare earth elements by selective chlorination from iron-rare earth permanent magnets according to the present invention have been described, but various implementation modifications are possible within the limit not departing from the scope of the present invention. It is self-evident.

Therefore, the scope of the present invention is limited to the described embodiments and should not be defined, and should be defined by the claims and equivalents as well as the claims to be described later.

That is, it should be understood that the above-described embodiments are illustrative in all respects and not limiting, and the scope of the present invention is indicated by the claims to be described later rather than the detailed description, and the meaning and scope of the claims and All changes or modified forms derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

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Claims (18)

(Step 1) pulverizing an iron-rare earth-based permanent magnet, a permanent magnet crushing step;
(Step 2) A mixing step of the permanent magnet and zinc chloride, in which the iron-rare earth permanent magnet pulverized product and the zinc chloride melt obtained in step 1 are mixed in a weight ratio of 1:0.4 to 1:3.0, where no iron chloride is added. ;
(Step 3) selectively chlorinating rare earths by heating the mixture at a temperature of 800K or higher to selectively chlorinate rare earths; And
(Step 4) separating the obtained rare earth chloride, a step of separating the rare earth chloride;
A method for recovering rare earth elements from an iron-rare earth permanent magnet by a selective chlorination method comprising a.
The method of claim 1,
In step 1 above,
The iron-rare earth-based permanent magnet is characterized in that the neodymium-iron-boron (Nd-Fe-B)-based permanent magnet,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 1,
In step 1 above,
The iron-rare earth-based permanent magnet is characterized in that the waste permanent magnet scrap or permanent magnet sludge,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 1,
In step 1 above,
The iron-rare earth-based permanent magnet is characterized in that pulverized to a particle size of 100㎛ to 2mm,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 1,
In step 1 above,
The iron-rare earth-based permanent magnet is characterized in that pulverized to a particle size of 300㎛ to 600㎛,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
delete The method of claim 1,
In step 2,
The iron-rare earth-based permanent magnet pulverized product and zinc chloride are mixed in a weight ratio of 1:1.8 to 1:2.7 ,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
delete The method of claim 1,
In step 2,
The zinc chloride is heated to a temperature of 600K or higher to melt, and then mixed with an iron-rare earth-based permanent magnet pulverized product,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
delete The method of claim 1,
In step 3 above,
Characterized in that by heating the mixture at a temperature of 900 ~ 1000K to selectively chlorinated,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 1,
In step 3 above,
Characterized in that heating the mixture for 1 to 5 hours,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 1,
In step 3 above,
Characterized in that heating the mixture for 1.5 to 2.5 hours,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 1,
In step 4,
Characterized in that the rare earth element chloride is separated by vacuum distillation,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 14,
The vacuum distillation is characterized in that it is carried out at a pressure of 1x10 ^-3 to 1x10 ^-5 atm,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
The method of claim 14,
The vacuum distillation is characterized in that it is carried out at a pressure of 5x10 ^-3 to 5x10 ^-4 atm,
A method of recovering rare earth elements from iron-rare earth permanent magnets by selective chlorination.
A mixture of rare earth chlorides recovered according to the method of any one of claims 1 to 5, 7, 9, and 11 to 16.
The method of claim 17,
A mixture of rare earth chlorides, characterized in that it contains neodymium (Nd) chloride or dysprosium (Dy) chloride.

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