Method for recovering all rare earth elements from rare earth magnetic material waste

Abstract

The application provides a method for recycling all rare earth elements in rare earth magnetic material waste, comprising the following steps: firstly, the rare earth magnetic material waste is crushed and combusted and oxidized to obtain fully oxidized products; then, the fully oxidized products obtained in the above step are mixed with carbon, and after heat treatment reduction and cooling, metal materials and rare earth oxides are obtained after separation. The application firstly removes impurities, crushes and oxidizes the materials, and converts rare earth metals and other metals into oxides. The oxides of iron and copper are reduced to metal by carbon reduction body. The metal is in liquid state, and the oxide is in solid state. The metal and the oxide are effectively separated by physical method after pouring into a mold and cooling. The application can realize the full recycling of metals in rare earth magnetic material waste, and has the advantages of simple operation, continuous controllable process, low cost, no need of using acid and alkali, no waste water, no emission of toxic gas, no waste, and suitability for continuous operation.

Description

Technical Field

[0001] This invention belongs to the field of rare earth magnetic material waste recycling technology, and relates to a method for recovering all rare earth elements from rare earth magnetic material waste. Background Technology

[0002] Neodymium iron boron permanent magnets are widely used in defense, aerospace, medical devices, computers, electronics, robotics, and new energy vehicle industries due to their superior magnetic properties.

[0003] Currently, the global annual production of R-Fe-B permanent magnets exceeds 300,000 tons. During the manufacturing process, waste materials such as magnet fragments, cutting chips, grinding chips, and ultrafine powder account for 25-35% of the input materials. Moreover, over time, permanent magnets used as components in various products will gradually reach their end-of-life and be scrapped. Common applications of R-Fe-B permanent magnets in fields such as power machinery, medical devices, toys, packaging, hardware machinery, and aerospace include permanent magnet motors, loudspeakers, magnetic separators, computer disk drives, and magnetic resonance imaging equipment. Existing technologies also disclose similar recycling solutions. For example, CN97120123.4 discloses a method for recycling rare earth compounds, which includes the following steps: (1) preliminary treatment of the raw materials; (2) leaching of rare earth compounds with an acid solution; (3) filtration; (4) precipitation of a solution containing rare earth metal ions; and (5) drying and calcination of the precipitate. However, the method used in this technical solution requires the use of acid more than twice, the washing with clean water, and more than two drying and roasting processes. This consumes a large amount of acid, and the resulting acidic solution requires treatment, consuming significant amounts of water and energy. Not only is the process lengthy, but the rare earth recovery rate is also low. Simultaneously, a large amount of iron contained in the magnetic waste is discharged as a salt solution or piled up as other solid waste. Small amounts of other metals such as copper, aluminum, cobalt, and niobium are also treated as waste and not recycled. For example, CN201580016947.4 also discloses a method for recovering rare earth elements, specifically: after oxidizing the object containing at least rare earth elements and iron group elements, the rare earth elements are separated and recovered as oxides from the iron group elements by heat treatment in the presence of carbon. However, this method also has the following drawbacks: ① Due to the use of vacuum or inactive atmosphere, the equipment structure is complex and expensive; the vacuum level is difficult to achieve the target value during the reaction with gas release, and the operating time is long. ② The layering of carbon and oxide materials results in poor contact between carbon and iron oxides. Calculations and practice have shown that the reaction products of carbon with iron oxide or magnetite are mainly carbon monoxide—a solid-solid reaction. Poor contact will seriously affect the reaction rate and extent, potentially leading to excessively high iron oxide content. ③ Resources are not fully utilized; the utilization of iron group metals and other minor metals has not been realized. ④ Operational convenience is poor.

[0004] Therefore, how to provide a more suitable method to recycle the various elements contained therein, especially rare earth elements, in a low-cost and green manner has become an important technical issue and one of the problems that many front-line researchers in the industry urgently need to solve. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide a method for recovering all rare earth elements from rare earth magnetic material waste. This is a method for processing rare earth magnetic material waste that fully utilizes the metals in the waste, achieving complete recovery and utilization of the metals in the rare earth magnetic materials. The present invention can recover rare earth oxides and other metals from rare earth magnetic material waste. This method is simple to operate, low-cost, involves continuous acid and alkali recycling, produces no waste, is suitable for continuous operation, and is more suitable for promotion and application in large-scale industrial production.

[0006] This invention provides a method for recovering all rare earth elements from rare earth magnetic material waste, comprising the following steps:

[0007] 1) After crushing and oxidizing rare earth magnetic material waste, fully oxides are obtained;

[0008] 2) The oxides obtained in the above steps are mixed with carbon, reduced by heat treatment, cooled, and separated to obtain metallic materials and rare earth oxides.

[0009] Preferably, the particle size of the crushed rare earth magnetic material waste is less than or equal to 0.061 mm;

[0010] The combustion oxidation method is carried out in an oxygen-containing atmosphere;

[0011] The oxygen volume content of the oxygen-containing atmosphere is 4% to 21%.

[0012] Preferably, the combustion oxidation temperature is greater than or equal to 500°C;

[0013] The combustion oxidation time is 12 to 24 hours.

[0014] Preferably, the rare earth magnetic material waste contains one or more rare earth elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium;

[0015] The mass ratio of the fully oxide to carbon is such that, based on the Fe element in the fully oxide, the mass ratio of Fe to carbon is (2.4–2.8):1;

[0016] The carbon includes one or more of blast furnace coke, pitch coke, and charcoal.

[0017] Preferably, the carbon includes rare earth molten salt electrolysis waste anodes and / or waste graphite tanks;

[0018] The heat treatment reduction temperature is greater than or equal to 710℃;

[0019] The heat treatment reduction time is 4 to 6 hours.

[0020] Preferably, the separation method includes peeling;

[0021] After cooling, the rare earth oxides are located in the upper layer of the material.

[0022] The rare earth oxides have a loose, clump-like structure.

[0023] Preferably, the rare earth oxides further include one or more of carbon, aluminum oxides, titanium oxides, niobium oxides, and iron oxides;

[0024] The aluminum oxide contains 0.1% to 0.5% by mass of rare earth oxides.

[0025] Preferably, the titanium oxide has a mass content of 0.03% to 0.10% in the rare earth oxides;

[0026] The niobium oxide has a mass content of 0.03% to 0.3% in the rare earth oxides;

[0027] The iron oxide has a mass content of 0.3% to 10% in the rare earth oxides.

[0028] Preferably, the metallic material comprises an alloy of iron group elements;

[0029] The metallic material also includes one or more of rare earth elements, aluminum elements, and carbon elements.

[0030] Preferably, the rare earth element has a mass content of 90% to 99.5% in the metallic material;

[0031] The aluminum element has a mass content of 0.03% to 0.10% in the metallic material;

[0032] The carbon content in the metallic material is 0.005% to 0.1% by mass.

[0033] This invention provides a method for recovering all rare earth elements from rare earth magnetic material waste, comprising the following steps: first, the rare earth magnetic material waste is crushed and oxidized by combustion to obtain fully oxides; then, the fully oxides obtained in the above steps are mixed with carbon, reduced by heat treatment, cooled, and separated to obtain metal materials and rare earth oxides. Compared with the prior art, this invention creatively designs a recovery method with a specific process route and process parameters. This is a method for fully utilizing the metals in rare earth magnetic material waste to achieve complete recovery and utilization of the metals in rare earth magnetic materials. This invention can recover rare earth oxides and other metals from rare earth magnetic material waste. The method is simple to operate, low-cost, involves continuous acid and alkali circulation, produces no waste, and is suitable for continuous operation.

[0034] This invention involves first removing impurities, crushing, and oxidizing the material to convert rare earth metals and iron into oxides. Then, a carbon reducing agent is used to reduce the oxides of iron, copper, etc., back to metals. The metals are in a liquid state, while the oxides are in a solid state. The mixture is poured into a mold, cooled, and then physically separated from the oxides. This recycling process enables the complete recovery and utilization of metals from rare earth magnetic material waste. It is simple and convenient to operate, the process is continuous and controllable, low-cost, requires no acids or alkalis, produces no wastewater, emits no toxic gases, generates no waste, and causes minimal environmental pollution. It is suitable for continuous operation and is particularly suitable for large-scale industrial production and application.

[0035] Experimental results show that the method for recovering all rare earth elements from rare earth material waste provided by this invention has a recovery rate of more than 92.5%, which is greater than 90% in the industry. Moreover, the recovery path is simple, no waste is generated, and the cost is low. Detailed Implementation

[0036] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims.

[0037] There are no particular restrictions on the source of any raw materials used in this invention; they can be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0038] There are no particular restrictions on the purity of any raw materials used in this invention. However, this invention preferably uses industrial-grade pure materials or materials with conventional purity used in the field of neodymium iron boron magnet recycling.

[0039] This invention provides a method for recovering all rare earth elements from rare earth magnetic material waste, comprising the following steps:

[0040] 1) After crushing and oxidizing rare earth magnetic material waste, fully oxides are obtained;

[0041] 2) The oxides obtained in the above steps are mixed with carbon, reduced by heat treatment, cooled, and separated to obtain metallic materials and rare earth oxides.

[0042] In this invention, "all rare earth elements" preferably refers to the recovery of all rare earth elements from rare earth magnetic material waste, including light rare earths and / or heavy rare earths. This recovery method belongs to the pyrometallurgical recovery method.

[0043] This invention first involves crushing and oxidizing rare earth magnetic material waste to obtain fully oxidized materials.

[0044] In this invention, the particle size of the crushed rare earth magnetic material waste is preferably less than or equal to 0.061 mm, more preferably less than or equal to 0.06 mm, and less than or equal to 0.059 mm.

[0045] In this invention, the combustion oxidation is preferably carried out in an oxygen-containing atmosphere.

[0046] In this invention, the oxygen volume content of the oxygen-containing atmosphere is preferably 4% to 21%, more preferably 8% to 17%, and even more preferably 11% to 13%.

[0047] In this invention, the combustion oxidation temperature is preferably greater than or equal to 500°C, more preferably greater than or equal to 600°C, and even more preferably greater than or equal to 800°C. Specifically, it can be 500–1450°C, or 600–1350°C, or 700–1250°C, or 800–1150°C.

[0048] In this invention, the combustion oxidation time is preferably 12-24 hours, more preferably 14-22 hours, and even more preferably 16-20 hours.

[0049] In this invention, the rare earth magnetic material waste preferably contains one or more rare earth elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium, and more preferably one rare earth element selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

[0050] Finally, the present invention mixes the fully oxide obtained in the above steps with carbon, reduces it by heat treatment, cools it, and separates it to obtain metal materials and rare earth oxides.

[0051] In this invention, the mass ratio of the fully oxide to carbon is, based on the Fe element in the fully oxide, preferably (2.4-2.8):1, more preferably (2.45-2.75):1, more preferably (2.5-2.7):1, and even more preferably (2.55-2.65):1.

[0052] In this invention, the carbon preferably includes one or more of blast furnace coke, pitch coke and charcoal, and more preferably blast furnace coke, pitch coke or charcoal.

[0053] In this invention, the carbon preferably includes rare earth molten salt electrolysis waste anodes and / or waste graphite cells, more preferably rare earth molten salt electrolysis waste anodes or waste graphite cells.

[0054] In this invention, the heat treatment reduction temperature is preferably greater than or equal to 710°C, more preferably greater than or equal to 750°C, or greater than or equal to 800°C. Specifically, it can be 710–1450°C, 800–1200°C, or 900–1100°C.

[0055] In this invention, the heat treatment reduction time is preferably 4 to 6 hours, more preferably 4.4 to 5.6 hours, and even more preferably 4.8 to 5.2 hours.

[0056] In this invention, the separation method preferably includes peeling.

[0057] In this invention, after cooling, the rare earth oxides are preferably located in the upper layer of the material.

[0058] In this invention, the rare earth oxide preferably has a loose, clump-like structure.

[0059] In this invention, the rare earth oxides preferably include one or more of carbon, aluminum oxide, titanium oxide, niobium oxide, and iron oxide, more preferably carbon, aluminum oxide, titanium oxide, niobium oxide, or iron oxide. Specifically, the iron oxides preferably include iron(II,III) oxide and iron(III) oxide, wherein iron(II) oxide is ≤10% and iron(III) oxide is >90%.

[0060] In this invention, the mass content of the aluminum oxide in the rare earth oxide is preferably 0.1% to 0.5%, more preferably 0.15% to 0.45%, more preferably 0.2% to 0.4%, and even more preferably 0.25% to 0.35%.

[0061] In this invention, the mass content of the titanium oxide in the rare earth oxide is preferably 0.03% to 0.10%, more preferably 0.04% to 0.09%, more preferably 0.05% to 0.08%, and even more preferably 0.06% to 0.07%.

[0062] In this invention, the mass content of the niobium oxide in the rare earth oxide is preferably 0.03% to 0.3%, more preferably 0.08% to 0.25%, and even more preferably 0.13% to 0.2%.

[0063] In this invention, the mass content of the iron oxide in the rare earth oxide is preferably 0.3% to 10%, more preferably 2% to 8%, and even more preferably 4% to 6%.

[0064] In this invention, the metallic material preferably comprises an alloy of iron group elements.

[0065] In this invention, the metal material preferably includes one or more of rare earth elements, aluminum elements and carbon elements, and more preferably rare earth elements, aluminum elements or carbon elements.

[0066] In this invention, the mass content of the rare earth element in the metallic material is preferably 90% to 99.5%, more preferably 92% to 98%, and even more preferably 94% to 96%.

[0067] In this invention, the mass content of aluminum in the metallic material is preferably 0.03% to 0.10%, more preferably 0.04% to 0.09%, more preferably 0.05% to 0.08%, and even more preferably 0.06% to 0.07%.

[0068] In this invention, the mass content of carbon in the metallic material is preferably 0.005% to 0.1%, more preferably 0.01% to 0.08%, and even more preferably 0.03% to 0.06%.

[0069] This invention provides a complete and detailed overall technical solution to better improve recycling efficiency and process continuity, reduce recycling costs and environmental impact. The specific steps for recovering all rare earth elements from the aforementioned rare earth magnetic material waste are as follows:

[0070] A method for recovering all rare earth elements from rare earth magnetic material waste includes the following steps:

[0071] Step (1): Add the pulverized material to the rotary kiln for full oxidation;

[0072] Step (2): Mix the fully oxidized material with an appropriate amount of carbon powder evenly and place it into the heating device;

[0073] Step (3): The heating device is heated so that the carbon particles and the oxides of the iron group elements can undergo a full reduction reaction, and the oxides of the iron group elements are reduced to iron group metals.

[0074] Step (4): Pour the material from step (3) into a mold, and cool the mold with water until it reaches below 100°C;

[0075] Step (5): Separate the cooled material from step (4) to obtain rare earth oxides, trace amounts of one or more of aluminum oxides, titanium oxides, and niobium oxides, as well as an iron group element alloy. The iron group element alloy can be directly sold to steelmaking enterprises. Specifically, the iron group element alloy is at the bottom, and the rare earth oxides are relatively loose, allowing for easy separation by peeling.

[0076] Specifically, carbon is first selected from rare earth molten salt electrolysis waste anodes or waste graphite cells.

[0077] Specifically, the carbon can also be selected from blast furnace coke, pitch coke or charcoal.

[0078] Specifically, the particle size of the processed material after crushing in step (1) is less than 0.061 mm (250 mesh).

[0079] Specifically, the processed materials containing at least rare earth elements and iron group elements are materials that have been degreased and have had impurities reduced to appropriate levels.

[0080] Specifically, the oxidation device can be selected from an atmosphere-protected rotary kiln, an atmosphere furnace, or a tunnel kiln.

[0081] Specifically, the smelting equipment can be selected from medium frequency furnace, industrial frequency furnace, or high frequency induction furnace.

[0082] Specifically, the magnetic material waste contains one or more rare earth elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium.

[0083] Specifically, the particle size of the processed material after the reduced oxide is pulverized is less than 0.061 mm (250 mesh).

[0084] The present invention provides a method for recovering all rare earth elements from rare earth magnetic material waste. This recovery method, with a specific process route and parameters, is a method for fully utilizing the metals in rare earth magnetic material waste to achieve complete recovery and utilization of the metals in the rare earth magnetic materials. This invention can recover rare earth oxides and other metals from rare earth magnetic material waste. The method is simple to operate, low-cost, involves continuous acid / alkali recycling, produces no waste, and is suitable for continuous operation.

[0085] This invention involves first removing impurities, crushing, and oxidizing the material to convert rare earth metals and iron into oxides. Then, a carbon reducing agent is used to reduce the oxides of iron, copper, etc., back to metals. The metals are in a liquid state, while the oxides are in a solid state. The mixture is poured into a mold, cooled, and then physically separated from the oxides. This recycling process enables the complete recovery and utilization of metals from rare earth magnetic material waste. It is simple and convenient to operate, the process is continuous and controllable, low-cost, requires no acids or alkalis, produces no wastewater, emits no toxic gases, generates no waste, and causes minimal environmental pollution. It is suitable for continuous operation and is particularly suitable for large-scale industrial production and application.

[0086] Experimental results show that the method for recovering all rare earth elements from rare earth material waste provided by this invention has a recovery rate of more than 92.5%, which is greater than 90% in the industry. Moreover, the recovery path is simple, no waste is generated, and the cost is low.

[0087] To further illustrate the present invention, the following describes in detail a method for recovering all rare earth elements from rare earth magnetic material waste, in conjunction with embodiments. However, it should be understood that these embodiments are implemented under the premise of the technical solution of the present invention, and provide detailed implementation methods and specific operating procedures. They are only for further illustrating the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0088] Example 1

[0089] The R-Fe-B ultrafine powder was subjected to combustion treatment in a rotary kiln at 800℃ for 120 minutes, oxidizing the material into oxides, of which iron oxides accounted for 49.3% by mass. The oxidized material was then mixed with carbon powder (ash content less than 1%) at a carbon to iron oxide mass ratio of 1:6.0. The mixed material was added to an induction furnace, heated to atmospheric temperature, and treated at 1350℃ for 30 minutes. The material was then poured into a casting ladle and rapidly cooled to below 200℃. After cooling to room temperature, the metal blocks and particles were separated from the other materials.

[0090] In Example 1 of this invention, 102 kg of oxide was added, and after reduction, 35.76 kg of metal and 48.93 kg of oxide were obtained. The rare earth element yield was 95.15%.

[0091] The rare earth element content of metals was determined using ICP-AES, the iron content of oxides was determined using the standard method of GB / T 12690.6-2017, and carbon was determined using a carbon-sulfur analyzer.

[0092] See Table 1, which shows the content analysis of major elements in rare earth oxides and metal alloys in Example 1 of the present invention.

[0093] Table 1

[0094] project Fe Pr Nd Gd Al C Phase A 99.5 0.01 0.01 0 0.42 0.25 Phase B 2.22 19.41 77.62 0.483 0.076 0.01

[0095] Example 2

[0096] For irregular R-Fe-B blocks, first crush them into materials smaller than 0.061mm using a high-speed crusher, then use a rotary kiln for combustion treatment at 800℃ for 120 minutes. The material is oxidized into oxides, of which iron oxides account for 69.89% by mass. Take 20kg of the oxidized material and mix it with 2.33kg of graphite powder, then add it to a medium-frequency furnace in three portions and melt for 210 minutes each time. Pour the melted material into a casting mold (the mold needs to be water-cooled), and after cooling to near room temperature, separate the metal blocks from other materials.

[0097] In Example 2 of this invention, 12.9 kg of metal and 8.02 kg of oxide were obtained after smelting. The rare earth element yield was 93.5%.

[0098] See Table 2, which shows the content analysis of major elements in rare earth oxides and metal alloys in Example 2 of the present invention.

[0099] Table 2

[0100] project Fe Pr Nd Ce Gd Al C Phase A 99.5 0.01 0.01 0.01 0 0.02 0.237 Phase B 3.52 16.41 51.21 28.2 0.483 0.196 0.035

[0101] Example 3

[0102] For R-Fe-B grinding powder, non-metallic oxides are first removed using a magnetic separator, and then it is subjected to combustion treatment in a rotary kiln at 850℃ for 120 minutes. The material is oxidized into oxides, of which iron oxides account for 69.5% by mass. 20 kg of the deoxidized material is mixed with 2.0 g of graphite powder and added to a 50 kg medium-frequency furnace in three portions. The mixture is smelted for 180 minutes, and then the material is poured into a ladle (water-cooled). After cooling to near room temperature, the metal blocks, metal particles and other materials are separated.

[0103] In Example 3 of this invention, 12.54 kg of metal and 8.52 kg of oxide were obtained after smelting. The rare earth element yield was 92.57%.

[0104] See Table 3, which shows the content analysis of major elements in rare earth oxides and metal alloys in Example 3 of the present invention.

[0105] Table 3

[0106] project Fe Pr Nd Ce Gd Si C Phase A 99.5 0.01 0.01 0.01 0 0.032 0.178 Phase B 4.57 16.40 51.22 26.7 0.483 0.046 0.055

[0107] The above provides a detailed description of a method for recovering all rare earth elements from rare earth magnetic material waste. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of these embodiments are merely for the purpose of helping to understand the method and core ideas of this invention, including the best mode, and also to enable any person skilled in the art to practice this invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention. The scope of protection of this patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the textual description of the claims, or if they include equivalent structural elements that are not substantially different from the textual description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. A method for recovering all rare earth elements from rare earth magnetic material waste, characterized by, Includes the following steps: 1) After crushing and burning the rare earth magnetic material waste, fully oxides are obtained; The combustion oxidation method is carried out in an oxygen-containing atmosphere; The oxygen volume content of the oxygen-containing atmosphere is 4% to 17%; The rare earth magnetic material waste contains one or more rare earth elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, scandium, and yttrium. 2) The oxides obtained in the above steps are mixed with carbon, and after being reduced by heat treatment in an atmospheric environment, they are poured into a mold for cooling and separation to obtain metal materials and rare earth oxides. After cooling, the rare earth oxides are located in the upper layer of the material. The carbon includes one or more of blast furnace coke, pitch coke and charcoal; The rare earth oxides have a loose, clump-like structure; The separation method includes peeling.

2. The recycling method according to claim 1, characterized in that, The particle size of the crushed rare earth magnetic material waste is less than or equal to 0.061 mm.

3. The recycling method according to claim 1, characterized in that, The combustion oxidation temperature is greater than or equal to 500℃; The combustion oxidation time is 12~24h.

4. The recycling method of claim 1, wherein, The mass ratio of the fully oxide to carbon is such that, based on the Fe element in the fully oxide, the mass ratio of Fe to carbon is (2.4~2.8):

1.

5. The recycling method of claim 1, wherein, The carbon includes rare earth molten salt electrolysis waste anodes and / or waste graphite cells.

6. The recycling method of claim 1, wherein, The heat treatment reduction temperature is greater than or equal to 710℃; The heat treatment reduction time is 4~6 hours.

7. The recycling method according to claim 1, characterized in that, The rare earth oxides also include one or more of carbon, aluminum oxides, titanium oxides, niobium oxides, and iron oxides; The aluminum oxide has a mass content of 0.1% to 0.5% in the rare earth oxides.

8. The recycling method according to claim 7, characterized in that, The titanium oxide has a mass content of 0.03% to 0.10% in the rare earth oxides; The niobium oxide has a mass content of 0.03% to 0.3% in the rare earth oxides; The iron oxide has a mass content of 0.3% to 10% in the rare earth oxides.

9. The recycling method according to claim 1, characterized in that, The metallic material includes alloys of iron group elements; The metallic material also includes one or more of rare earth elements, aluminum elements, and carbon elements.

10. The recycling method according to claim 9, characterized in that, The rare earth element has a mass content of 90% to 99.5% in the metallic material; The aluminum element has a mass content of 0.03% to 0.10% in the metallic material; The carbon content in the metallic material is 0.005% to 0.1% by mass.