Method for recovering rare earths from rare earth-containing magnets

Abstract

By using solid aqua regia when recovering rare earths from rare earth-containing magnets, rare earths can be recovered safely. The method includes a crushing step (S5) for crushing neodymium magnets extracted from waste products, a step of adding the crushed neodymium magnets in the crushing step (S5) to a solid aqua regia, which is a composite molten salt, and chlorinating the rare earths and Fe while heating (S11), coagulating the molten salt by cooling the rare earth chlorides to room temperature (S12), crushing the solid aqua regia containing the coagulated rare earth chlorides, recovering the rare earth chlorides in a first leaching (S13), and recovering the rare earth chlorides and FeCl 2 or oxalic acid (COOH) in a solvent containing NaCl 2 is added, and only the rare earth oxalate is selectively precipitated and recovered in the second leaching (S15).

Description

[Technical field]

[0001] The present invention relates to a method for recovering rare earths from rare earth-containing magnets such as neodymium magnets used in parts of precision instruments such as smartphones and hard disks that convert electrical energy into sound or vibration, and in drive motors and electric power steering devices for hybrid and electric vehicles. [Background technology]

[0002] Rare earth magnets, such as neodymium magnets, are made up primarily of neodymium (Nd), iron (Fe), and boron (B) and are known as permanent magnets with the strongest magnetic force. Neodymium magnets have a large magnetic force per unit volume, so they can maintain a satisfactory magnetic force even when miniaturized, fully meeting the demand for miniaturized parts and are used in a variety of industrial fields.

[0003] Neodymium magnets, which have such strong magnetic force, are used in precision equipment such as smartphones and hard disks, and in the drive motors of electric vehicles (EVs, HVs), etc. A method has been proposed to extract neodymium magnets from discarded hard disks and electric vehicle motors and recover rare earth elements from them.

[0004] A technique for recovering rare earths from used rare earth-containing magnets has been proposed. For example, Patent Document 1, JP 2017-115175 A, "Method for recovering rare earth elements from rare earth magnets," proposes a method for recovering rare earth elements from rare earth magnets, which includes a first step of immersing a rare earth magnet in water, adding nitric acid, and maintaining the liquid temperature at 50 to 95°C to dissolve the rare earth magnet and generate a solution, a second step of adjusting the pH of the solution to a range of 1.5 to 2.5, heating it to 65 to 95°C to generate an iron compound, and recovering and washing out a supernatant liquid containing rare earth magnet components, a third step of contacting an extractant with the supernatant to extract the rare earth magnet components into an organic phase, and a fourth step of extracting the rare earth magnet components from the organic phase into the nitric acid side, crystallizing them, and further calcining them to generate rare earth oxides. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2017-115175 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, the "method of recovering rare earth elements from rare earth magnets" in Patent Document 1 uses nitric acid, which has acute toxicity, as a dissolving solution. Nitric acid can cause chemical burns if it comes into contact with the skin, and can cause blindness if it gets into the eyes. In addition, this method of recovering rare earth elements involves heating the dissolving solution, which generates harmful fumes (solid fine particles) and gases that, if inhaled by workers, can attack the mucous membranes of the throat and respiratory tract, and can cause dental corrosion and pulmonary edema.

[0007] Furthermore, rare earth-containing magnets such as neodymium magnets have a strong magnetic force, and so hands, fingers, etc. may be pinched between the magnets, or between the magnets and magnetic bodies such as iron pieces, resulting in injury. Therefore, if processing work is carried out while the magnetic force of the neodymium magnets is maintained, there is a problem that the magnets are likely to be attracted to processing containers, reaction tanks, handling tools, etc., making the work complicated. Furthermore, grinding magnets with such properties into fine powder can be an even more complicated task.

[0008] The inventors of the present invention considered that rare earths could be safely recovered from rare earth-containing magnets (neodymium magnets) by using so-called solid aqua regia. Solid aqua regia is a complex molten salt consisting of iron chloride (III) (FeCl3) and an alkali metal (potassium chloride (KCl) or sodium chloride (NaCl)). All of these chemical substances are less toxic and easier to handle than the chemicals used in conventional wet methods. Furthermore, treatment can be carried out at around 400°C, which is lower than in conventional dry methods. The inventors of the present invention therefore focused on using solid aqua regia in rare earth recovery treatments.

[0009] The present invention has been devised to fundamentally solve these problems. That is, an object of the present invention is to provide a method for recovering rare earths from rare-earth-containing magnets, which uses solid aqua regia when recovering rare earths from rare-earth-containing magnets, thereby enabling safe recovery of rare earths. [Means for solving the problem]

[0010] The method for recovering rare earths from a rare earth-containing magnet of the present invention comprises the steps of: Has a magnet whose main component is iron A method for recovering rare earths from rare earth-containing magnets that are incorporated in waste products, comprising the steps of: A crushing step (S5) of crushing the rare earth-containing magnets extracted from the waste products; The rare earth-containing magnet pulverized in the pulverization step (S5) is Iron(III) chloride (FeCl 3 ) and an alkali metal (potassium chloride (KCl) or sodium chloride (NaCl)A chlorination process (S11) in which the rare earth and Fe are chlorinated by adding them to a solid aqua regia, which is a composite molten salt, and heating them; a molten salt solidification step (S12) in which the rare earth chloride treated in the chlorination step (S11) is cooled to room temperature to solidify the molten salt; The solid aqua regia containing the rare earth chloride solidified in the molten salt solidification step (S12) is pulverized and leached with water. do A first leaching step (S13); Solid aqua regia containing rare earth chloride treated in the first leaching step (S13), By solid-liquid separation Solid phase Remove the magnet residue, Liquid phase In addition to rare earth chlorides, FeCl2 and KCl or Recover the solvent containing NaCl First solid-liquid separation step (S14a) and, The above First solid-liquid separation step (S14a) Recovered in Liquid phase Rare earth chlorides and FeCl2 KCl or In a solvent containing NaCl 、 Add oxalic acid (COOH)2 do A second leaching step (S15); Rare earths treated in the second leaching step (S15) Selectively precipitate and recover only oxalate Second solid-liquid separation step (S14b) and The above Second solid-liquid separation step (S14b) Recovered in Solid phase Rare Earth Oxalates salt The method is characterized in that the rare earths are recovered by drying the wastewater.

[0011] The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of: Has a magnet whose main component is iron A method for removing neodymium magnets incorporated in waste products and recovering rare earths from the neodymium magnets, comprising the steps of: A crushing process (S5) for crushing the neodymium magnets extracted from the waste products; The neodymium magnet crushed in the crushing step (S5) is Iron(III) chloride (FeCl 3 ) and an alkali metal (potassium chloride (KCl) or sodium chloride (NaCl) A chlorination process (S11) in which the rare earth and Fe are chlorinated by adding them to a solid aqua regia, which is a composite molten salt, and heating them; a molten salt solidification step (S12) in which the rare earth chloride treated in the chlorination step (S11) is cooled to room temperature to solidify the molten salt; The solid aqua regia containing the rare earth chloride solidified in the molten salt solidification step (S12) is pulverized and leached with water. do A first leaching step (S13); Solid aqua regia containing rare earth chloride treated in the first leaching step (S13), By solid-liquid separation Solid phase Remove the magnet residue, Liquid phase In addition to rare earth chlorides, FeCl2 and KCl or Recover the solvent containing NaCl No. 1 Solid-liquid separation process (S14 a )and, The above No. 1 Solid-liquid separation process (S14 a ) was collected Liquid phase Rare earth chlorides and FeCl2 KCl or In a solvent containing NaCl 、 Add oxalic acid (COOH)2 do A second leaching step (S15); Rare earths treated in the second leaching step (S15) Selectively precipitate and recover only oxalate Second Solid-liquid separation process (S14 b ) and The above Second Solid-liquid separation process (S14 b ) was collected Solid phase Rare Earth Oxalates salt Dry the neodymium The present invention is characterized in that the above-mentioned is recovered.

[0012] Before the grinding step (S5), Discarded products Rare earth-containing magnet with attached parts Or neodymium magnet It is preferable that the method further comprises a demagnetization step (S3) of demagnetizing the magnetic material. In the chlorination treatment step (S11), chlorination and demagnetization can be carried out simultaneously by heat treatment at a temperature exceeding the Curie temperature. Effect of the Invention

[0013] The rare earth recovery method of the present invention for rare earth-containing magnets uses solid aqua regia, a composite molten salt, which is less toxic and easier to handle than substances used in conventional wet processing methods. Compared to conventional wet processing methods, this method does not substantially dissolve Fe, so it can reduce chemical consumption and also suppress the generation of waste liquid, which is a high environmental load. Processing can be carried out at around 400°C, which is lower than conventional dry processing methods, reducing energy consumption and simplifying equipment. but Furthermore, since chlorination, pulverization, and demagnetization can be carried out simultaneously, the process itself can be greatly simplified.

[0014] In the rare earth recovery method of the present invention, the chlorination of rare earths and the dissolution of Fe proceed simultaneously, making it possible to efficiently extract rare earths from rare earth-containing magnet scrap without the need for fine pulverization. In particular, rare earth-containing magnets are known to contain iron(III) chloride (FeCl 3 ) turns the iron into a salt, allowing the solid aqua regia to act on the rare earths such as neodymium contained inside the magnet, making it possible to efficiently extract the rare earths without having to crush the iron into a fine powder. [Brief description of the drawings]

[0015] [Figure 1] This is an Ellingham diagram for the chlorides of Fe (iron), Nd (neodymium), and Dy (dysprosium). [Diagram 2] FIG. 1 is a ternary phase diagram showing the state of a three-phase molten salt of FeCl2-FeCl3-NaCl. [Diagram 3] FIG. 2 is a flow diagram showing chemical reactions in a method for recovering rare earths from a rare earth-containing magnet. [Figure 4] FIG. 1 shows an example of a method for recovering rare earths from neodymium magnets, which are rare earth-containing magnets, and is a flow chart of the pre-treatment stage. [Diagram 5] FIG. 1 shows an example of a rare earth recovery method for neodymium magnets, which are rare earth-containing magnets, and is a flow chart of the chemical treatment stage. [Figure 6] This is an image showing a molten salt solidified by placing a neodymium magnet in solid aqua regia and then cooling the chlorinated rare earth chloride to solidify the molten salt. [Figure 7]1 is an image showing a solvent obtained by first leaching a molten salt solidified material with water and removing magnet residues by first solid-liquid separation. [Figure 8] This is an image showing the magnet residue after it has been removed by the first solid-liquid separation in the first leaching, with a magnet being brought close from the outside. [Figure 9] This is an image showing the solvent recovered after crushing solid aqua regia containing rare earth chlorides, performing a first leaching with water, and removing magnet residues by a first solid-liquid separation, resulting in a solvent containing rare earth chlorides as well as FeCl2 and NaCl. [Figure 10] This is an image showing a solvent that contains rare earth chlorides, FeCl2, and NaCl, and in the second leaching, oxalic acid (COOH)2 is added to the solvent to selectively precipitate and recover only the oxalate salt. [Figure 11] This is an image showing the rare earths recovered by drying the rare earth oxalate recovered in the second leaching process. [Figure 12] This is a table showing images taken with a SEM (scanning electron microscope) of materials recovered after a processing time of 2 hours, and the recovery rates confirmed by analysis with an EDS (energy dispersive X-ray analyzer). The images show FeCl2-based and FeCl3-based materials. [Figure 13] This is a table showing images taken with a SEM (scanning electron microscope) of materials recovered after a 4-hour recovery process, and the recovery rates confirmed by analysis with an EDS (energy dispersive X-ray analyzer). The images show FeCl2-based and FeCl3-based materials. [Figure 14] This is a table showing images taken with a SEM (scanning electron microscope) of materials recovered after a 6-hour recovery process, and the recovery rates confirmed by analysis with an EDS (energy dispersive X-ray analyzer). The images show FeCl2-based and FeCl3-based materials. [Figure 15] 13 is a graph showing the correlation between recovery processing time and recovery rate, and an image showing the properties of each recovered material. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The method for recovering rare earths from rare-earth-containing magnets of the present invention is a method for recovering rare earths from rare-earth-containing magnets using solid aqua regia, by removing rare-earth-containing magnets such as neodymium magnets that are used in parts of precision instruments such as smartphones and hard disks for converting electrical energy into sound or vibration, and for use in drive motors and electric power steering in hybrid and electric vehicles.

[0017] <Application of "Solid Aqua Regia" to Rare Earth Magnets> Figure 1 shows the Ellingham diagram for chlorides of Fe (iron), Nd (neodymium), and Dy (dysprosium). Figure 2 shows the ternary phase diagram of the three-phase molten salt FeCl2-FeCl3-NaCl. The solid aqua regia used in the present invention is a complex molten salt consisting of iron chloride (III) (FeCl3) and an alkali metal (potassium chloride (KCl) or sodium chloride (NaCl)). As shown in the Ellingham diagram of Fe (iron), Nd (neodymium), and Dy (dysprosium) chlorides in Figure 1, rare earths can be salified not only with FeCl3 but also with FeCl2 (iron (II) chloride). For rare earth-containing magnets, treating only with iron chloride (II) FeCl2 allows selective treatment of only the rare earths. Since iron chloride (II) FeCl2 has a melting point of 950K (677°C), which is higher than iron chloride (III) FeCl3, it is necessary to make it possible to treat it at low temperatures. Therefore, in the present invention, a composite molten salt including FeCl3, which has a melting point of about 300°C, is used, making it possible to melt and salify it at low temperatures.

[0018] In the phase diagram of the three-phase molten salt FeCl2-FeCl3-NaCl at 650K (377℃) in Figure 2, the composition in the gray region, for example the composition indicated by the star (molar ratio FeCL2:FeCL3:NaCl = 0.35‥0.1:0.55), indicates that a completely molten state will be achieved even at 650K. This temperature makes it possible to simplify the processing equipment and reduce energy consumption. Note that molten saltation at 650K can also be achieved if KCl is used instead of NaCl.

[0019] In the case of this composite molten salt, the rare earth is salified in the reaction shown in Chemical Formula 1 in Chemical Formula 1, and the Fe in the magnet is salified in the reaction shown in Chemical Formula 2 in Chemical Formula 2. The FeCl2 generated in this reaction is consumed in the salification of the rare earth, so the overall reaction proceeds as shown in Chemical Formula 3 in Chemical Formula 3. As the salification of the rare earth and the dissolution of Fe proceed simultaneously, rare earth can be efficiently extracted from the crushed neodymium magnet powder without the need to finely grind the neodymium magnet.

[0020] [ka]

[0021] [ka]

[0022] [ka]

[0023] <Each reaction phase> FIG. 3 is a flow diagram showing the chemical reactions in the method for recovering rare earths from rare-earth-containing magnets. The rare earth recovery method of the present invention allows treatment under milder conditions than those required for conventional wet methods, and also suppresses the generation of waste liquid. The reaction proceeds in the following phases. (1) Chlorination and demagnetization of magnet scraps using solid aqua regia. Crushed magnet scraps are placed in solid aqua regia and heated to 360 to 400°C, and rare earths and Fe are chlorinated by the reaction shown in Chemical Formula 3. After the treatment, the molten salt is cooled to room temperature to solidify and recover. At this time, chlorination and demagnetization are simultaneously performed by treating it at a temperature above the Curie temperature.

[0024] [ka]

[0025] (2) Rare earths are recovered by dissolving rare earth chlorides through leaching and adding oxalic acid (COOH)2. The recovered solid aqua regia is leached with water (first leaching). No. 1 Magnet residues and other materials are removed by solid-liquid separation, and the solvent containing rare earth chlorides, FeCl2, and NaCl is recovered. (3) Oxalic acid (COOH)2 is added to the recovered solvent and leached (second leaching). The solubility of rare earths, alkali metals, and Fe oxalates (FeC2O4) in water is as shown in Table 1, which lists the solubility of various oxalic acid compounds in water, so it is possible to selectively precipitate and recover only rare earth oxalates by controlling the pH level.

[0026] [Table 1] EXAMPLES

[0027] Fig. 4 shows an example of a rare earth recovery method for neodymium magnets that contain rare earths, and is a flow chart of the pre-treatment stage. Fig. 5 shows an example of a rare earth recovery method for neodymium magnets that contain rare earths, and is a flow chart of the chemical treatment stage. Next, a method for recovering rare earths from neodymium magnets of rare-earth-containing magnets using the above-mentioned solid aqua regia will be described as a recycling technology. The recovery method of Example 1 is a method for extracting neodymium magnets, which are representative of rare-earth-containing magnets incorporated into discarded products such as smartphones, hard disks, and electric vehicles, using the above-mentioned solid aqua regia, and recovering rare earths from these neodymium magnets. The rare-earth recovery method of Example 1 from rare-earth-containing magnets mainly consists of a pretreatment stage and a chemical treatment stage, and has the following treatment steps.

[0028] <Pretreatment stage> The pre-processing stage is a processing method having, in the order of steps, an image identification process S1, a dismantling and sorting process S2, a demagnetization process S3, a surface treatment process S4 and a crushing process S5.

[0029] The image identification process S1 is a process in which motors are taken from discarded smartphones, hard disks, drive motors for electric vehicles such as EVs and HEVs, starters (cell motors) for conventional reciprocating engine automobiles, etc., and the magnets used in the motors are identified as being neodymium magnets or other magnets, for example, using deep learning technology in computer AI technology. Neodymium magnets can be identified using an XRF (X-ray fluorescence) analysis device as an analytical device. Of course, the analytical device is not limited to this XRF analysis device.

[0030] In the dismantling and sorting process S2, the neodymium magnet motors identified in the image identification process S1 are removed and dismantled, the motor housings and neodymium magnets are separated, and the exterior iron and castings are recycled. These metals can be recycled as they are. In rare cases, neodymium magnets can be recovered by manual dismantling.

[0031] When processing neodymium magnets with parts attached, a demagnetization process S3 is provided after the dismantling and sorting process S2. The demagnetization process S3 is a process for demagnetizing or reducing the magnetic force of neodymium magnets, in which the motor is held under high temperature conditions and heated to the Curie temperature. Separating neodymium magnets from motors with parts attached is dangerous due to their high magnetic force. Also, when neodymium magnets that still retain their magnetic force are handled, they are attracted to magnetic materials, making the work complicated. For this reason, demagnetizing them at this stage makes the processing work after the crushing process S5 easier.

[0032] In the surface treatment process S4, the neodymium magnets used in the motors are plated, oiled, and painted. Neodymium magnets tend to rust, and when they rust, they become easily demagnetized. Therefore, the neodymium magnets are protected with plating, oil, and paint. These must be removed as they will hinder smooth processing in the next chemical treatment stage.

[0033] The crushing step S5 is a step in which the neodymium magnets are crushed to a particle size of about 500 μmm to 1 mm. This is to facilitate smooth processing in the chemical processing stage. Coarse crushing is performed with a hammer, and fine crushing is performed using a ball mill or the like. In the rare earth recovery method of the present invention, rare earths and Fe are chlorinated in the chemical processing stage, so processing is possible without crushing, but the subsequent processing time tends to be long. The particle size is preferably about 500 μm to 1 mm, but it is possible to make it finer than this. However, this has the disadvantage of increasing the work cost and time. In addition, it is preferable for the particle size to be uniform, so classification is performed as necessary.

[0034] <Chemical treatment stage> The chemical treatment steps of the method for recovering rare earth from neodymium magnets in Example 1 are a chlorination treatment step S11, a molten salt solidification step S12, a first leaching step S13, No. 1 Solid-liquid separation process S14 a , second leaching process S15, Second Solid-liquid separation process S14 b , a filtering step S16, and a drying step S17.

[0035] The neodymium magnets pulverized in the pulverization step S5 of the pretreatment stage are first treated in the chlorination step S11. In this chlorination step S11, the pulverized neodymium magnets are placed in a furnace together with solid aqua regia powder, which is a composite molten salt, and are heated. The rare earth and Fe are chlorinated. The ratio of the pulverized neodymium magnets to the solid aqua regia powder is, for example, 1:2. The furnace is filled with a nitrogen atmosphere. The heating temperature is 670K, and the chlorination is carried out for 6 hours. In addition, in the chemical treatment stage including the chlorination treatment step S11, since the reaction is extremely highly reactive, the reaction vessel must be of an appropriate size and material according to the amount of treatment, such as the material of the reaction tank, the means of transport to the next step, and the method of adding solid aqua regia. It is also necessary to take safety measures against the leakage of chlorine gas.

[0036] Figure 6 shows an image of the molten salt solidified by putting a neodymium magnet into solid aqua regia and cooling the rare earth chloride that had been chlorinated to solidify the molten salt. Figure 7 shows the molten salt solidified by first leaching with water. No. 1 This is an image showing the solvent from which magnet residues have been removed by solid-liquid separation. No. 1 13 is an image showing the magnet residue after removal by solid-liquid separation, with a magnet brought close from the outside. The chlorination process S11 is followed by the molten salt solidification process S12, in which the rare earth chloride treated in the chlorination process S11 is cooled to room temperature to solidify the molten salt. After solidification, the solid aqua regia was separated into black and white parts, as shown in Figure 6.

[0037] The first leaching step S13 follows the molten salt solidification step S12. This first leaching step S13 is a step in which the solid aqua regia containing rare earth chlorides solidified in the molten salt solidification step S12 is crushed and leached with water. The reason why the expressions "first" and "second" are used here is not to indicate the grade, but simply to indicate the difference between the two leaching steps.

[0038] After the first leaching process S13 No. 1 Solid-liquid separation process S14 a It is. No. 1 Solid-liquid separation process S14 a is a process for removing magnet residues and recovering a solvent containing rare earth chlorides, FeCl2, and NaCl. No. 1 Solid-liquid separation process S14 a A suction filtration method was used. After solidification, the solid aqua regia separated into black and white parts as shown in Figure 6. The black parts consisted of fine flakes and powder, and remained in the solid phase after the first leaching step S13. When a magnet was brought close, it was strongly attracted as shown in Figure 8, so both are thought to be Fe, and based on their shapes, the fine flakes are thought to be sample residue, and the powder part is thought to be Fe powder produced after the magnet was dissolved via the reaction shown in chemical formula 3. Furthermore, since all of the particles had lost their magnetic properties, treatment with solid aqua regia could simultaneously perform chlorination, pulverization, and demagnetization. On the other hand, the white areas shown in Figure 6 are presumed to be rare earth chlorides produced by the reaction shown in Chemical Formula 3, and are dissolved into the liquid phase during the leaching process.

[0039] [ka]

[0040] In the first leaching step S13, the treatment process itself is carried out under relatively mild conditions (water is the only solvent, at room temperature). However, the iron powder recovered as a by-product turns to rust in water, so it must be removed quickly. It has also been suggested that when an aqueous solution of iron chloride comes into contact with air, iron hydroxide is produced, which gels and affects filtration. When treating large quantities at a factory, the treatment process must be carried out in a way that avoids these problems.

[0041] Also, No. 1 Solid-liquid separation process S14 a Currently, this is done by suction filtration, which allows for quick processing. However, this is not the only method.

[0042] No. 1 Solid-liquid separation process S14 a Next is the second leaching step S15. This second leaching step S15 is a leaching step in which oxalic acid (COOH)2 is added to the solvent containing the rare earth chlorides, FeCl2 and NaCl recovered in the first leaching step S13, and only the oxalate salts are selectively precipitated and recovered. Second Solid-liquid separation process S14 b This separates the rare earth oxalate (solid phase) from the liquid phase of a solvent containing FeCl2 and NaCl.

[0043] Figure 9 is an image showing the state after solid aqua regia containing rare earth chlorides is crushed, subjected to the first leaching with water, magnetic residues are removed by solid-liquid separation, and a solvent containing rare earth chlorides as well as FeCl2 and NaCl is recovered. Figure 10 is an image showing the solvent after oxalic acid (COOH)2 is added to the solvent containing rare earth chlorides, FeCl2 and NaCl in the second leaching, and only the oxalates are selectively precipitated and recovered. Figure 11 is an image showing the rare earths recovered by drying the rare earth oxalates recovered in the second leaching process. Figure 9 shows the state of the solvent obtained in the second leaching step S15 after filtering in the filtration step S16. Figure 10 shows the state after adding oxalic acid (COOH)2 and leaving it to stand for one day. Figure 11 shows the final recovered product. The solvent obtained by removing the residue is pale green. When oxalic acid (COOH)2 is added to this solvent, a white precipitate precipitates. When recovered by filtration, it was pale green, which is due to FeCl2 that remained after processing, or FeC204 that precipitated at the same time and was mixed in as an impurity.

[0044] <SEM image of the final recovered material and composition of the final precipitate> FIG. 12 shows images of recovered materials collected for 2 hours using a SEM (scanning electron microscope) and a table showing the recovery rates confirmed by analysis using an EDS (energy dispersive X-ray analyzer), for FeCl2-based and FeCl3-based recovered materials. FIG. 13 shows images of recovered materials collected for 4 hours using a SEM and a table showing the recovery rates confirmed by analysis using an EDS, for FeCl2-based and FeCl3-based recovered materials. FIG. 14 shows images of recovered materials collected for 6 hours using a SEM and a table showing the recovery rates confirmed by analysis using an EDS, for FeCl2-based and FeCl3-based recovered materials. FIG. 15 shows a graph showing the correlation between recovery time and recovery rate, and an image showing the properties of each recovered material. The relationship between the processing time of the above-mentioned recovery processing method and the finally recovered precipitate was compared. Figures 12 to 15 show SEM (scanning electron microscope) images and EDS (energy dispersive X-ray analyzer) analysis and confirmed recovery rates. For example, it contained about 40 wt% Nd, about 2 wt% Dy, and other impurities such as Fe and O. On the other hand, since no chlorine (Cl) was contained, it was mainly a mixture of oxalates or oxides of Nd and Dy, with FeC2O4 and iron oxide (FeOx) mixed in. Since neodymium magnets contain about 60 wt% Fe, the recovery method of the present invention can selectively separate and recover rare earths to a certain extent.

[0045] It should be noted that the present invention is not limited to the above-described embodiment of the invention, and can of course be modified in various ways without departing from the gist of the present invention, so long as rare earths can be safely recovered by using solid aqua regia when recovering rare earths from rare-earth-containing magnets. [Industrial Applicability]

[0046] The method for recovering rare earths from rare earth-containing magnets of the present invention is not limited to neodymium magnets, but can also recover rare earths from samarium-cobalt magnets, praseodymium magnets, samarium-iron-nitrogen magnets, and the like. [Explanation of symbols]

[0047] S1 Image recognition process S2 Dismantling and sorting process S3 Demagnetization process S4 Surface treatment process S5 Crushing process S21 Demagnetization process S22 Dismantling and sorting process S11 Chlorination process S12 Molten salt solidification process S13 First leaching process S14 a No. 1 Solid-liquid separation process S14 b SecondSolid-liquid separation engineering S15 No. 2 Railroad Project S16 Overhaul Engineering S17 Drying Engineering

Claims

1. A method for recovering rare earths from a rare earth-containing magnet incorporated in a waste product having a magnet mainly composed of iron, comprising: A crushing step (S5) of crushing the rare earth-containing magnets extracted from the waste products; a chlorination treatment step (S11) in which the rare earth-containing magnet pulverized in the pulverization step (S5) is introduced into solid aqua regia, which is a composite molten salt composed of iron chloride (III) (FeCl 3 ) and an alkali metal (potassium chloride (KCl)), and the rare earth and Fe are chlorinated while being heated; a molten salt solidification step (S12) in which the rare earth chloride treated in the chlorination treatment step (S11) is cooled to room temperature to solidify the molten salt; a first leaching step (S13) of pulverizing the solid aqua regia containing rare earth chloride solidified in the molten salt solidification step (S12) and leaching it with water; The solid aqua regia containing rare earth chlorides treated in the first leaching step (S13) is subjected to solid-liquid separation to remove solid magnet residues, and the rare earth chlorides in the liquid phase as well as FeCl ２ a first solid-liquid separation step (S14a) of recovering a solvent containing KCl; The liquid phase rare earth chloride and FeCl recovered in the first solid-liquid separation step (S14a) ２ In a solvent containing KCl, oxalic acid (COOH) ２ A second leaching step (S15) of adding A second solid-liquid separation step (S14b) of selectively precipitating and recovering only the rare earth oxalate treated in the second leaching step (S15), A method for recovering rare earths from a rare-earth-containing magnet, comprising drying the solid phase rare earth oxalate recovered in the second solid-liquid separation step (S14b) to recover the rare earth.

2. A method for recovering rare earths from a rare earth-containing magnet incorporated in a waste product having a magnet mainly composed of iron, comprising: A crushing step (S5) of crushing the rare earth-containing magnets extracted from the waste products; a chlorination treatment step (S11) in which the rare earth-containing magnet pulverized in the pulverization step (S5) is introduced into solid aqua regia, which is a composite molten salt composed of iron (III) chloride (FeCl 3 ) and sodium chloride (NaCl), and the rare earth and Fe are chlorinated while being heated; a molten salt solidification step (S12) in which the rare earth chloride treated in the chlorination treatment step (S11) is cooled to room temperature to solidify the molten salt; a first leaching step (S13) of pulverizing the solid aqua regia containing rare earth chloride solidified in the molten salt solidification step (S12) and leaching it with water; The solid aqua regia containing rare earth chlorides treated in the first leaching step (S13) is subjected to solid-liquid separation to remove solid magnet residues, and the rare earth chlorides in the liquid phase as well as FeCl ２ a first solid-liquid separation step (S14a) of recovering a solvent containing NaCl; The liquid phase rare earth chloride and FeCl recovered in the first solid-liquid separation step (S14a) ２ In a solvent containing NaCl, oxalic acid (COOH) ２ A second leaching step (S15) of adding A second solid-liquid separation step (S14b) of selectively precipitating and recovering only the rare earth oxalate treated in the second leaching step (S15), A method for recovering rare earths from a rare-earth-containing magnet, comprising drying the solid phase rare earth oxalate recovered in the second solid-liquid separation step (S14b) to recover the rare earth.

3. A method for removing neodymium magnets incorporated in waste products having magnets mainly composed of iron, and recovering rare earths from the neodymium magnets, comprising: A crushing step (S5) of crushing the neodymium magnets extracted from the waste products; a chlorination treatment step (S11) in which the neodymium magnets pulverized in the pulverization step (S5) are introduced into solid aqua regia, which is a composite molten salt composed of iron (III) chloride (FeCl 3 ) and an alkali metal (potassium chloride (KCl)), and the rare earth and Fe are chlorinated while being heated; a molten salt solidification step (S12) in which the rare earth chloride treated in the chlorination treatment step (S11) is cooled to room temperature to solidify the molten salt; a first leaching step (S13) of pulverizing the solid aqua regia containing rare earth chloride solidified in the molten salt solidification step (S12) and leaching it with water; The solid aqua regia containing rare earth chlorides treated in the first leaching step (S13) is subjected to solid-liquid separation to remove solid magnet residues, and the rare earth chlorides in the liquid phase as well as FeCl ２ a first solid-liquid separation step (S14a) of recovering a solvent containing KCl; The liquid phase rare earth chloride and FeCl recovered in the first solid-liquid separation step (S14a) ２ In a solvent containing KCl, oxalic acid (COOH) ２ A second leaching step (S15) of adding A second solid-liquid separation step (S14b) of selectively precipitating and recovering only the rare earth oxalate treated in the second leaching step (S15), A method for recovering rare earths from a rare earth-containing magnet, comprising drying the solid phase rare earth oxalate recovered in the second leaching step (S15) and the second solid-liquid separation step (S14b) to recover neodymium.

4. A method for extracting neodymium magnets incorporated in waste products having magnets mainly composed of iron, and recovering rare earths from the neodymium magnets, comprising: A crushing step (S5) of crushing the neodymium magnets extracted from the waste products; a chlorination treatment step (S11) in which the neodymium magnets pulverized in the pulverization step (S5) are introduced into solid aqua regia, which is a composite molten salt composed of iron (III) chloride (FeCl 3 ) and sodium chloride (NaCl), and the rare earth and Fe are chlorinated while being heated; a molten salt solidification step (S12) in which the rare earth chloride treated in the chlorination treatment step (S11) is cooled to room temperature to solidify the molten salt; a first leaching step (S13) of pulverizing the solid aqua regia containing rare earth chloride solidified in the molten salt solidification step (S12) and leaching it with water; The solid aqua regia containing rare earth chlorides treated in the first leaching step (S13) is subjected to solid-liquid separation to remove solid magnet residues, and the rare earth chlorides in the liquid phase as well as FeCl ２ a first solid-liquid separation step (S14a) of recovering a solvent containing NaCl; The liquid phase rare earth chloride and FeCl recovered in the first solid-liquid separation step (S14a) ２ In a solvent containing NaCl, oxalic acid (COOH) ２ A second leaching step (S15) of adding A second solid-liquid separation step (S14b) of selectively precipitating and recovering only the rare earth oxalate treated in the second leaching step (S15), A method for recovering rare earths from a rare earth-containing magnet, comprising drying the solid phase rare earth oxalate recovered in the second leaching step (S15) and the second solid-liquid separation step (S14b) to recover neodymium.

5. The rare earth recovery method for rare earth-containing magnets according to claim 1 or 2, further comprising a demagnetization step (S3) of demagnetizing the rare earth-containing magnets to which the parts of the scrap products are attached, prior to the crushing step (S5).

6. The method for recovering rare earths from rare earth-containing magnets according to claim 3 or 4, further comprising a demagnetization step (S3) of demagnetizing the neodymium magnets to which the parts of the scrapped products are attached, prior to the crushing step (S5).

7. 5. The method for recovering rare earths from a rare earth-containing magnet according to claim 1, 2, 3 or 4, characterized in that in the chlorination treatment step (S11), chlorination and demagnetization are carried out simultaneously by a heat treatment exceeding the Curie point.

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