JP5401497B2 - Rare earth element separation and recovery method - Google Patents

Description

  The present invention relates to a technique for separating and collecting rare earth elements, and more particularly to a method for separating and collecting rare earth elements from a composition containing a plurality of types of rare earth elements.

  In recent years, the importance of sustainable global environmental protection has been recognized, and industrial systems and traffic systems that can minimize the use of fossil fuels have been vigorously developed. Examples of such environmentally compatible systems and products include wind power generation systems, railway systems, hybrid vehicles, electric vehicles, energy-saving air conditioners, and the like.

  One of the main devices of these environmentally-friendly systems and products is high-efficiency rotating electrical machines (motors and generators), and magnets containing rare earth elements (so-called rare earth magnets) are widely used in these high-efficiency rotating electrical machines. ing. For example, rare earth magnets used in rotating electrical machines such as drive motors for hybrid vehicles and compressors for air conditioners are required to have a high coercive force even in high temperature environments (eg, about 200 ° C). In addition to neodymium, iron, and boron It contains a lot of expensive and heavy heavy rare earth elements (for example, dysprosium). Rare earth magnets are indispensable now, and demand is expected to increase in the future.

  On the other hand, since rare earth elements are difficult and expensive to separate and purify a single element, development of technologies and alternative materials for reducing the amount of use while maintaining the performance of magnets has been intensively studied. However, it seems that it will take time to put these technologies into practical use. Therefore, it is an important technique to separate and recover rare earth elements from waste materials (for example, rare earth magnets in waste motors, shavings (sludge) generated in the production process of rare earth magnets) and recycle them.

  For example, Patent Document 1 discloses a divalent trivalent mixture in which the average valence of two or more rare earth ions is 2 or more and 3 or less by halogenating a rare earth element in a mixture containing a plurality of rare earth elements or compounds thereof. Producing a mixture containing a rare earth halide which is not dissolved in an aqueous solution or an organic solvent, and then utilizing the difference in properties between the divalent rare earth halide and the trivalent rare earth halide, There has been proposed a rare earth element separation method characterized by separating elements into at least two groups. According to Patent Document 1, it is said that the separation factor between rare earth elements can be dramatically increased, and mutual separation can be performed more efficiently than in the conventional method. Furthermore, when separating from rare earth concentrates such as phosphates, steps such as acid dissolution, filtration, precipitation removal of impurities, concentration, neutralization, and drying, which are essential for conventional wet methods, can be omitted. It is said that the cost can be greatly reduced.

  Patent Document 2 discloses a method for recovering a rare earth element from a material containing a rare earth element and an iron group element, and a rare earth element such as a rare earth magnet scrap or sludge is added to a gaseous or molten iron chloride. Select a rare earth element as a chloride from the substance by contacting a substance containing an iron group element and proceeding the chlorination reaction of the rare earth element in the substance while maintaining the metallic state of the iron group element in the substance. There has been proposed a method for recovering a rare earth element characterized by having a step of recovering automatically. According to Patent Document 2, it becomes possible to extract and separate only high-purity rare earth components from materials containing rare earth elements and iron group elements, such as rare earth magnet scraps or sludges, particularly wastes, and lower cost rare earth elements. It is said that the magnet recycling law can be established.

JP 2001-303149 A JP 2003-73754 A

  As mentioned above, the demand for rare earth magnets is expected to increase in the future. On the other hand, rare earth elements such as neodymium and dysprosium, which are rare earth magnet raw materials, are unevenly distributed on the earth, and technologies for separating, recovering and recycling rare earth elements from the viewpoint of ensuring the stability of raw materials and effective use of resources. Is becoming more important than before.

  Accordingly, an object of the present invention is to provide a method capable of separating and recovering rare earth elements at a higher yield than the prior art.

(I) One aspect of the present invention is a method for separating and recovering a plurality of types of rare earth elements in order to achieve the above object, wherein an oxygen source is used for a mixture containing halides of the types of rare earth elements. Causing a rare earth halide of the first group and a rare earth oxyhalide of the second group of rare earth elements to reach a chemical equilibrium state by chemical reaction in the presence of the rare earth halide, the rare earth oxyhalide, The rare earth halide is selectively dissolved in water and extracted into a liquid phase, and the rare earth oxyhalide remains as a solid phase, and the liquid phase from which the rare earth halide is extracted Separating the first group of rare earth elements and the second group of rare earth elements by solid-liquid separation from the solid phase of the remaining rare earth oxyhalide. A method for separating and recovering rare earth elements is provided. In the present invention, the rare earth halide means a fluoride, chloride, bromide or iodide of a rare earth element, and is represented by the general chemical formula REX ₃ (RE: rare earth element, X: halogen element). . The rare earth oxyhalide is represented by the general chemical formula REOX (O: oxygen).

  (II) Another aspect of the present invention is a method for separating and recovering a plurality of types of rare earth elements in order to achieve the above object, wherein a halogen source is used for the mixture containing the oxides of the plurality of types of rare earth elements. Causing a rare earth halide of the first group and a rare earth oxyhalide of the second group of rare earth elements to reach a chemical equilibrium state by chemical reaction in the presence of the rare earth halide, the rare earth oxyhalide, The rare earth halide is selectively dissolved in water and extracted into a liquid phase, and the rare earth oxyhalide remains as a solid phase, and the liquid phase from which the rare earth halide is extracted Separating the first group of rare earth elements and the second group of rare earth elements by solid-liquid separation of the remaining solid phase of the rare earth oxyhalide. It provides a method of separating and recovering rare earth elements and having a.

In addition, the present invention can be modified or changed as follows in the rare earth element separation and recovery methods (I) and (II).
(I) The halogen is chlorine.
(Ii) The neodymium is contained as the rare earth element of the first group, and dysprosium is contained as the rare earth element of the second group.

  (III) Still another embodiment of the present invention is a method for separating and recovering a plurality of types of rare earth elements in order to achieve the above object, wherein the compound contains a plurality of types of rare earth elements, iron, and boron. Forming a chloride-containing mixture by chlorination with iron chloride, and distilling the chloride-containing mixture from the chloride-containing mixture of the plurality of rare earth element chlorides. Separating the mixture, and chemically reacting the mixture of the plurality of rare earth chlorides in the presence of an oxygen source with the rare earth chloride of the first group and the rare earth element of the second group. A step of bringing the rare earth oxychloride into a chemical equilibrium state, and the rare earth chloride and the rare earth oxychloride are poured into water to selectively dissolve the rare earth chloride in water and into the liquid phase. Removing the rare earth oxychloride as a solid phase and separating the liquid phase from which the rare earth chloride is extracted from the solid phase of the remaining rare earth oxychloride by solid-liquid separation. There is provided a method for separating and recovering rare earth elements, comprising the step of separating rare earth elements from the second group of rare earth elements.

  (IV) Still another aspect of the present invention is a method for separating and recovering a plurality of types of rare earth elements in order to achieve the above object, wherein the compound containing the plurality of types of rare earth elements, iron, and boron is used. A step of performing a roasting treatment, a step of selectively leaching the plurality of rare earth elements by immersing the roasted compound in an acid, and precipitation of the plurality of rare earth elements from an acid leaching solution. Producing a product, producing a mixture of the plurality of rare earth oxides from the precipitate, and chemically reacting the mixture of the plurality of rare earth oxides in the presence of a chlorine source. The step of bringing the rare earth chloride of the first group rare earth and the rare earth oxychloride of the second group rare earth into a chemical equilibrium state, and introducing the rare earth chloride and the rare earth oxychloride into water. By said rare A step of selectively dissolving a chloride in water and extracting it into a liquid phase to leave the rare earth oxychloride as a solid phase; and a liquid phase from which the rare earth chloride has been extracted and the remaining rare earth oxychloride. There is provided a method for separating and recovering a rare earth element, comprising the step of separating the first group of rare earth elements and the second group of rare earth elements by solid-liquid separation of the solid phase of the product.

Further, the present invention can add the following improvements and changes to the rare earth element separation and recovery methods (III) and (IV).
(Iii) The neodymium and dysprosium are included as the plurality of kinds of rare earth elements.
(Iv) The rare earth chloride is neodymium chloride, and the rare earth oxychloride is dysprosium oxychloride.

  According to the present invention, it is possible to provide a method capable of separating and recovering rare earth elements at a higher yield than the prior art. As a result, rare earth elements (for example, neodymium, dysprosium, etc.) can be separated with high precision from waste of rare earth magnets (for example, non-use, defective products, sludge, etc.), and the separated rare earth elements are recycled as raw materials. be able to. This can contribute to effective utilization of resources and stable securing of rare earth materials.

It is an equilibrium diagram showing the neodymium-oxygen-chlorine (Nd-O-Cl) chemical potential diagram and dysprosium-oxygen-chlorine (Dy-O-Cl) chemical potential diagram superimposed at 727 ° C (1000 K). . It is a cross-sectional schematic diagram which shows the state immediately after a separation process in an example of the distillation apparatus used for the separation process of rare earth elements and other elements. 2 is a chart showing an example of a powder X-ray diffraction pattern obtained in Example 1. FIG. It is a graph which shows the relationship between the density | concentration of the rare earth elements (Nd, Dy) melt | dissolved in water, and distillation temperature. 5 is a graph showing the relationship between the Nd concentration ratio (Nd / (Nd + Dy)) obtained from FIG. 4 and the distillation temperature.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In addition, this invention is not limited to embodiment taken up here, A combination and improvement are possible suitably in the range which does not change a summary.

[Basic principle of rare earth element separation method]
First, the basic principle of the method for separating rare earth elements in the present invention will be described. Here, as an example, separation using neodymium and dysprosium chloride will be described, but the present invention is not limited to this.

Figure 1 shows the equilibrium of the neodymium-oxygen-chlorine (Nd-O-Cl) chemical potential diagram and the dysprosium-oxygen-chlorine (Dy-O-Cl) chemical potential diagram at 727 ° C (1000 K). It is a state diagram. In FIG. 1, a solid line is a chemical potential diagram of neodymium, and a broken line is a chemical potential diagram of dysprosium. As shown in FIG. 1, in any case, the oxide (RE ₂ O ₃ ) is stable in the region where the oxygen potential is high and the chlorine potential is low, and the chloride (REC1) is used in the region where the chlorine potential is high and the oxygen potential is low. ₃ or RECl ₂ ) is stable, and the metal (RE) is stable in the region where the oxygen potential is low and the chlorine potential is low. Further, a stable region of oxychloride (REOCl) exists between the stable region of oxide and the stable region of chloride.

Here, in the region surrounded by ABCDE shown in FIG. 1, neodymium is stable in trivalent chloride (NdCl ₃ ), and dysprosium is stable in dysprosium oxychloride (DyOCl). Accordingly, if the potential of chlorine and oxygen can be controlled so as to fall within this ABCDE region, neodymium chloride and dysprosium oxychloride can coexist.

As an example of a method for fixing the potential of chlorine and oxygen so as to be in the ABCDE region, a mixture of NdCl ₃ and DyCl ₃ is used as a starting material, and magnesium (Mg) is used as a dechlorinating agent, and mixed in a crucible. The case where the chemical reaction is performed in the presence of an appropriate oxygen source will be described. In the equilibrium diagram of FIG. 1, the Mg / MgCl ₂ equilibrium line and the Mg / MgO equilibrium line based on the following chemical formulas (1) and (2) are indicated by thick solid lines. Although there is an MgO / MgCl ₂ equilibrium line, in the present invention, the system in which metal Mg coexists is mainly considered and omitted in FIG.

Attention is paid to the intersection of the equilibrium line based on the chemical formula (1) and the equilibrium line based on the chemical formula (2) in FIG. 1, that is, the three-phase equilibrium point (point F) of Mg / MgCl ₂ / MgO. At this three-phase equilibrium point, Nd and Dy are found to be in a stable state with NdCl ₃ and DyOCl, respectively. Here, considering the important conditions for realizing the chemical reaction of DyCl ₃ → DyOCl, DyCl ₃ properly takes in oxygen in the reaction system and the dechlorination reaction from DyCl ₃ proceeds sufficiently. Is mentioned. In order to allow the dechlorination reaction to proceed sufficiently, it is desirable to suppress the decrease in the activity of Mg by adding Mg in excess of the equivalent so that the reaction of chemical formula (1) proceeds smoothly to the right side.

On the other hand, examples of the oxygen source include moisture adsorbed on chlorides, oxides that may be present on the surface of the crucible, oxygen gas that cannot be removed by exhaust using a rotary pump or the like, and the like. In the present invention, even if the amount of these oxygen sources is not strictly controlled, if excess Mg is present, oxygen is fixed as MgO, so the three-phase equilibrium point (point F) of Mg / MgCl ₂ / MgO. ) Can control the potential of the system.

When the chemical reaction proceeds under the above conditions, Mg, MgCl ₂ , NdCl ₃ , and DyOCl mainly remain as residues after the completion of the reaction. Among these residues, Mg and MgCl ₂ have a high vapor pressure, and therefore can be discharged out of the system by exhausting / distilling with a rotary pump or the like. As a result, NdCl ₃ and DyOCl remain in the crucible.

Next, a residue composed of NdCl ₃ and DyOCl is poured into water. Since NdCl ₃ is soluble in water but DyOCl is insoluble, when these residues are put into water, only NdCl ₃ is dissolved in water (extracted in the liquid phase), and DyOCl remains as a solid phase. By separating this from solid and liquid, neodymium and dysprosium can be separated and recovered.

[Separation process of rare earth elements and other elements]
Next, a method for separating neodymium and dysprosium from a compound of a rare earth element such as a rare earth magnet and another element will be described. First, a procedure for obtaining a mixture of neodymium chloride and dysprosium chloride from a rare earth magnet containing neodymium, dysprosium, iron, and boron as main components will be described. The rare earth magnet often contains praseodymium, which is another rare earth element, but the physical and chemical behaviors of neodymium and praseodymium are very similar. Think.

  The separation process (procedure) of rare earth elements and other elements is basically the same as the process disclosed in Patent Document 2, but specifically, is as follows. As described above, it is preferable to use waste (for example, non-use, defective products, sludge, etc.) as the rare earth magnet for element separation, and it should be in powder form from the viewpoint of separation and recovery efficiency (chemical reaction efficiency). Is preferred. In the following, separation of rare earth magnets from sludge powder will be described as an example.

  FIG. 2 is a schematic cross-sectional view showing a state immediately after the separation step in an example of a distillation apparatus used in the separation step of rare earth elements and other elements. As shown in FIG. 2, the distillation apparatus 20 is a cylindrical vertical electric furnace having two vertical heaters (upper heater 1, lower heater 2, thermocouples 3, 3 ′) on the outer periphery of a vertical furnace core tube 4. Is the basic structure. The core tube 4 has an exhaust port 5, a gas introduction port 6, and an upper lid 7 so that the inside can be exhausted and replaced with gas. The exhaust port 5 is connected to a rotary pump or the like (not shown). In addition, in FIG. 2, although the bottomed core tube 4 was illustrated, the structure sealed with a lower cover may be sufficient. Moreover, the installation location of the exhaust port 5 and the gas introduction port 6 is not particularly limited.

  Inside the core tube 4, a high temperature side recovery unit 8 is installed in the region of the lower heater 2, and a low temperature side recovery unit 9 is disposed in the region of the upper heater 1. The crucible 10 containing the material to be separated by distillation is installed at the bottom of the high temperature side recovery unit 8.

First, the sludge powder dried using a dryer or the like is crushed. Thereafter, the crushed sludge powder, graphite powder, and iron dichloride (FeCl ₂ ) in excess of the stoichiometric amount are mixed and filled in the crucible 10. The crucible 10 is installed at the bottom of the high temperature side recovery unit 8 and inserted into the core tube 4 of the distillation apparatus 20. The inside of the furnace tube 4 is evacuated and replaced with an inert gas such as argon gas, and then heated at 700 to 900 ° C. while flowing an inert gas. As a result of this heat treatment, the mixed material in the crucible 10 chemically reacts, and a mixture of rare earth chloride, unreacted iron dichloride, iron or an iron group element alloy is obtained in the crucible 10 (mixture containing chloride). Generating step). The oxygen component fixed in the rare earth magnet sludge powder is gasified by the graphite powder (carbon component), and the generated gas is discharged out of the system by the flowing inert gas.

  Next, the obtained rare earth chloride, iron dichloride, iron or iron group element alloy mixture is subjected to distillation separation by heating with a rotary pump while reducing the pressure. At this time, the temperature of the upper heater 1 (maximum temperature of the low temperature side recovery unit 9) is maintained at 400 to 500 ° C, and the temperature of the lower heater 2 (maximum temperature of the high temperature side recovery unit 8) is maintained at 700 to 1100 ° C. It is preferable. As a result of this distillation separation, a condensed phase of iron dichloride is formed in the low temperature side recovery unit 9, a condensed phase of rare earth chloride is formed in the high temperature side recovery unit 8, and iron and iron group elements are contained in the crucible 10. The alloy remains as a residue (step of separating a mixture of chlorides of a plurality of rare earth elements). When the condensed phase in the high temperature side recovery unit 8 is recovered, a mixture of a plurality of types of rare earth chlorides is obtained. In the case of this example, specifically, a mixture of neodymium chloride and dysprosium chloride is obtained.

[Separation process of multiple types of rare earth elements]
Next, the process of separating rare earth elements from each other from the mixture of the rare earth chlorides recovered above will be described. Also in this step, the distillation apparatus 20 shown in FIG. 2 can be used. A mixture of the collected rare earth chlorides and a metal magnesium (Mg) in excess of the equivalent amount are mixed and filled in a crucible 10 made of molybdenum. At this time, since the rare earth chloride is rich in hygroscopicity, it is desirable to quickly weigh, mix and fill in a dry environment (for example, a drying room, a glove box, etc.) in order to avoid excessive moisture absorption. Further, graphite powder may be added in order to remove excess oxygen in the chemical reaction system.

  The filled crucible 10 is installed at the bottom of the high temperature side recovery unit 8 and inserted into the furnace core tube 4 of the distillation apparatus 20. The inside of the furnace tube 4 is evacuated and replaced with an inert gas such as argon gas, and then heated at 700 to 900 ° C. for 6 to 24 hours while flowing the inert gas. As a result of this heat treatment, the mixed material in the crucible 10 chemically reacts, and dysprosium oxychloride and magnesium chloride are obtained as products in the crucible 10, and neodymium chloride and magnesium metal are obtained as unreacted materials (first reaction). A step of bringing the rare earth chloride of the first group of rare earths and the rare earth oxychloride of the second group of rare earth elements into a chemical equilibrium state).

  After the above chemical reaction reaches a chemical equilibrium state, distillation separation is performed by evacuating with a rotary pump while keeping the furnace body at a high temperature. At this time, it is preferable that the temperature of the upper heater 1 is maintained at 400 to 500 ° C., and the temperature of the lower heater 2 is maintained at 900 to 1100 ° C. As a result of this distillation separation, a condensed phase 12 of metallic magnesium and a condensed phase 13 of magnesium chloride are formed in the low-temperature side recovery unit 9, and neodymium chloride and dysprosium oxychloride remain as main residual components in the crucible 10. To do.

  After the distillation separation, the distillation apparatus 20 is cooled to room temperature. The residue remaining in the crucible 10 is poured into pure water and stirred. As a result, neodymium chloride is preferentially dissolved and extracted in pure water, and dysprosium oxychloride remains as a solid phase residue (rare earth chloride is extracted into the liquid phase and the rare earth oxychloride is dissolved in the solid phase. As a process). Thereby, neodymium can be concentrated in the liquid phase. Next, the liquid phase from which the neodymium chloride is extracted and the solid phase of the remaining dysprosium oxychloride are subjected to solid-liquid separation (step of separating the first group of rare earth elements and the second group of rare earth elements). Thereby, neodymium and dysprosium can be separated.

[Rare earth oxide synthesis process]
After adjusting the pH of the neodymium chloride aqueous solution obtained above, a precipitant (eg, ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), ammonium hydrogen carbonate (NH ₄ HCO ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), oxalic acid ((COOH) ₂ ), sodium oxalate ((COONa) ₂ ), ammonium hydroxide (NH ₄ OH), etc.) A soluble neodymium salt precipitate is formed. The precipitate is filtered and dried, and then neodymium oxide can be recovered by baking at about 900 ° C. in the atmosphere.

On the other hand, the solid phase dysprosium oxychloride obtained above is dissolved in an acid (dilute hydrochloric acid, dilute nitric acid, etc.), adjusted to pH in the aqueous solution, and then precipitated with a precipitant (for example, ammonium carbonate (( NH ₄ ) ₂ CO ₃ ), ammonium bicarbonate (NH ₄ HCO ₃ ), sodium carbonate (Na ₂ CO ₃ ), sodium bicarbonate (NaHCO ₃ ), oxalic acid ((COOH) ₂ ), sodium oxalate ((COONa ₂ ), ammonium hydroxide (NH ₄ OH), etc.) is added to form a dysprosium salt precipitate which is sparingly soluble in water. After the precipitate is filtered and dried, dysprosium oxide can be recovered by baking at about 900 ° C. in the atmosphere.

[Reduction process to rare earth metal]
The neodymium oxide and dysprosium oxide recovered above can be reduced to metal neodymium and metal dysprosium by performing molten salt electrolysis using a fluoride bath or the like. These rare earth metals can be reused as raw materials for rare earth magnets.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to these.

[Example 1]
Separation and recovery from rare earth oxide mixtures were studied. Neodymium oxide (Nd ₂ O ₃ ) powder and dysprosium oxide (Dy ₂ O ₃ ) powder were used as starting materials for the rare earth oxide, and anhydrous dysprosium chloride (DyCl ₃ ) powder was used as the starting material for the chlorine source . As starting powder reagents, 3N grades manufactured by Kojundo Chemical Laboratory Co., Ltd. were used. Weigh and mix 2.5 mmol (0.84 g) Nd ₂ O ₃ powder, 2.5 mmol (0.93 g) Dy ₂ O ₃ powder, and 5.0 mmol (1.34 g) DyCl ₃ powder in a drying chamber. The reaction vessel was charged and sealed under a nitrogen atmosphere. Sealing was performed by capping a stainless steel reaction vessel and welding with argon.

  A reaction vessel in which the raw material powder was sealed was placed in an electric furnace, subjected to a chemical reaction at 800 ° C. for 6 hours, and allowed to cool to room temperature. The reaction container which became room temperature was taken out from the electric furnace, the reaction container was cut with a pipe cutter or the like, and a part of the powder after the chemical reaction was quickly put into water from the reaction container and stirred with a stirrer. On the other hand, powder X-ray diffraction measurement was performed on the remainder of the powder after the chemical reaction to identify the crystal phase. The result of the powder X-ray diffraction measurement is shown in FIG. FIG. 3 is a chart showing an example of a powder X-ray diffraction pattern obtained in Example 1.

As shown in FIG. 3, NdCl ₃ .6H ₂ O and DyOCl were identified from the X-ray diffraction pattern of the powder after the chemical reaction, but Nd ₂ used as a starting material for the rare earth oxide and chlorine source. O ₃ , Dy ₂ O ₃ , and DyCl ₃ peaks were not observed. That is, it was confirmed that the mixed powder of the rare earth oxide and the chlorine source was changed into a mixture of the rare earth chloride and the rare earth oxo chloride by the chemical reaction by the heat treatment. In addition, although neodymium chloride became hexahydrate, it is thought that this was adsorbed after sampling from the reaction container and before powder X-ray diffraction measurement.

  On the other hand, after insoluble components were filtered out from a sample put in water, Nd components and Dy components were quantitatively analyzed by ICP-AES method (inductively coupled plasma emission spectroscopy) for the non-turbid filtrate. As a result, the Nd concentration was 900 mg / L and the Dy concentration was 700 mg / L. In this example, since 5 mmol (0.72 g) of Nd and 10 mmol (1.63 g) of Dy are mixed in the raw material powder, Nd and Dy are eluted in an equivalent manner. The elution amount should be Nd: Dy = 31: 69 by mass ratio. On the other hand, the above result was Nd: Dy = 56: 44 by mass ratio, and it was confirmed that neodymium chloride was selectively extracted into water.

[Example 2]
Separation and recovery from rare earth chloride mixtures were studied. Co. Kojundo Chemical Laboratory Co. anhydrous NdCl ₃ using a powder of anhydrous DyCl ₃ powder, produced by Wako Pure Chemical Industries, Ltd. of metallic Mg powder (particle size as the starting material for the magnesium as a starting material of the rare earth chloride : About 0.5 mm, purity: 99.93%). 2.5 g each of NdCl ₃ powder and DyCl ₃ powder was weighed in a drying chamber, and 5.0 g of Mg powder was weighed and filled in a crucible 10 made of molybdenum. After stirring and mixing these powders with a shell, 0.2 g of high-temperature-treated graphite powder was separately weighed and charged so as to cover the previously prepared rare earth chloride powder. A desiccator was prepared in advance in a drying chamber, and a crucible charged with raw material powder was once sealed in the desiccator.

  Bring this desiccator to the vicinity of the distillation apparatus 20 shown in FIG. 2, open the desiccator lid, immediately take out the crucible 10 and place it on the bottom of the high-temperature side recovery unit 8, and the Inconel core of the distillation apparatus 20. Inserted into tube 4. Subsequently, the core tube 4 was immediately sealed with the upper lid 7, and the inside of the core tube 4 was decompressed with a rotary pump through the exhaust port 5. Although all operations after opening the desiccator were performed quickly, it was considered that some of the moisture in the air, which was the oxygen source, adhered to the raw material powder, the surface of the crucible, and the inner wall of the distillation apparatus.

  Next, the distillation apparatus 20 was heated to 300 ° C. and held for 12 hours or more, and the raw material powder and the inside of the furnace core tube 4 were vacuum-heated and dried, and then argon gas was introduced to bring the system to atmospheric pressure. In order to remove excess oxygen remaining in the reactor core tube 4 and the gas inlet 6 as much as possible, the operation of exhausting and introducing gas was further repeated five times. After introducing argon gas, the gas stream was maintained. Thereafter, the temperature of the lower heater 2 was set to 800 ° C. and the temperature of the upper heater 1 was set to 400 ° C. for 6 hours under an argon stream atmosphere, and the raw material powder was chemically reacted.

Thereafter, the rotary pump was evacuated for 3 hours while maintaining the temperature as it was, and an excess Mg that was supposed to remain in the crucible 10 and MgCl ₂ as a reaction product were subjected to distillation separation. After the distillation separation, the distillation apparatus 20 was cooled to room temperature while being evacuated to vacuum. According to the same procedure, when the temperature of the lower heater 2 is 900 ° C. and the temperature of the upper heater 1 is 450 ° C., and the temperature of the lower heater 2 is 1000 ° C. and the temperature of the upper heater 1 is 500 ° C. The case was done separately.

  After cooling to room temperature, the crucible 10 was removed from the distillation apparatus 20 and sampled. 0.5 g of the residue in the crucible 10 was weighed out, quickly poured into 50 mL of pure water, and stirred with a stirrer for 24 hours. At this time, when the distillation temperature (maximum temperature of the high temperature side recovery unit 8) was 800 ° C. and 900 ° C., it was observed that bubbles were remarkably generated and a part of the residue was dissolved. On the other hand, when the distillation temperature was 1000 ° C., no bubbles were observed and no residue was observed.

  After filtering insoluble components, the rare earth components contained in the non-turbid filtrate were quantitatively analyzed by ICP-AES method. The results are shown in FIGS. FIG. 4 is a graph showing the relationship between the concentration of rare earth elements (Nd, Dy) dissolved in water and the distillation temperature. FIG. 5 is a graph showing the relationship between the Nd concentration ratio (Nd / (Nd + Dy)) obtained from FIG. 4 and the distillation temperature. As can be seen from FIGS. 4 and 5, when the distillation temperature was 1000 ° C., neither Nd nor Dy was detected in the filtrate. On the other hand, when the distillation temperatures were 800 ° C. and 900 ° C., Nd was significantly detected in the solution compared to Dy. The ratio between the Nd concentration and the Dy concentration at this time was Nd: Dy = 87: 13 when the distillation temperature was 800 ° C., and Nd: Dy = 89: 11 when the distillation temperature was 900 ° C.

As described above, in this example, the charged composition of the rare earth chloride is 2.5 g of NdCl ₃ and DyCl ₃ (that is, the charged molar ratio of Nd element and Dy element is 49:51). From). The above results indicate that Nd chloride is remarkably dissolved in water, and Dy oxychloride is less soluble in water than Nd chloride and tends to remain as a solid phase. That is, it was confirmed that neodymium and dysprosium can be separated efficiently.

[Example 3]
We studied the separation and recovery of rare earth elements from waste materials of rare earth magnets (RE ₂ Fe ₁₄ B) containing neodymium, dysprosium, praseodymium, iron and boron. The mass composition of the rare earth magnet used was 61.2% Fe-23.1% Nd-3.5% Dy-2.0% Pr-1.0% B. The waste magnet is a defective product because cracks, chips, etc. occur after nickel plating in the manufacturing process.

  First, the waste magnet was roughly pulverized by heating at 800 ° C. in a hydrogen atmosphere using an electric furnace. As described above, the waste magnet was nickel-plated. However, since the nickel-plated film can be peeled off by the hydrogen pulverization step, the peeled-off plated film was separated from the magnet powder by sieving.

The obtained magnetic powder was mixed with FeCl ₂ powder as a chlorine source and placed in an iron crucible 10 and placed in the distillation apparatus 20 shown in FIG. The Inconel furnace core tube 4 is evacuated with a rotary pump and then replaced with argon gas. The temperature of the lower heater 2 is set to 800 ° C., the temperature of the upper heater 1 is set to 400 ° C., and maintained for 10 to 15 hours. Reaction was performed. Thereafter, the temperature of the lower heater 2 was raised to 1000 ° C., the temperature of the upper heater 1 was raised to 500 ° C., and vacuum distillation was performed for 3 hours while exhausting with a rotary pump. After vacuum distillation, the furnace core tube 4 was cooled in the furnace while maintaining a vacuum.

  After the furnace was cooled to room temperature, the condensate adhesion state of the high-temperature side recovery unit 8 and the low-temperature side recovery unit 9 was observed, and in the 800-500 ° C region of the high-temperature side recovery unit 8, light purple powder, light green powder The white powdery substance was condensed, and the orange powdery substance was condensed in the low temperature side recovery unit 9 at a temperature lower than 500 ° C. It was observed that these condensed substances absorb moisture in a short time when left in a general room. On the other hand, when these condensed substances are quickly collected and semi-quantitatively analyzed with an XRF apparatus (fluorescence X-ray analyzer), the condensed substances in the region of 800 to 500 ° C are mainly composed of rare earth elements (neodymium, praseodymium, dysprosium) compounds. It was confirmed that the content was 98%.

  If the same treatment as in Example 1 and / or Example 2 is performed on the mixture of rare earth compounds recovered above, neodymium, praseodymium and dysprosium can be separated from each other.

1 ... Upper heater, 2 ... Lower heater, 3, 3 '... Thermocouple, 4 ... Core tube, 5 ... Exhaust port,
6 ... Gas inlet, 7 ... Upper lid, 8 ... High temperature side recovery unit, 9 ... Low temperature side recovery unit, 10 ... Crucible,
11, 12, 13 ... condensed phase, 20 ... distillation equipment.

Claims (8)

A method for separating and recovering multiple types of rare earth elements,
A chemical reaction of the rare earth halide of the first group and the rare earth oxyhalide of the second group of rare earth elements by chemical reaction in the presence of an oxygen source to the mixture containing the halides of the plurality of rare earth elements. Reaching the equilibrium state; and
Introducing the rare earth halide and the rare earth oxyhalide into water to selectively dissolve the rare earth halide in water and extracting it in a liquid phase, leaving the rare earth oxyhalide as a solid phase; and
Separating the first group of rare earth elements and the second group of rare earth elements by solid-liquid separation of the liquid phase from which the rare earth halide is extracted and the solid phase of the remaining rare earth oxyhalide. A method for separating and recovering rare earth elements, comprising: A method for separating and recovering multiple types of rare earth elements,
A chemical reaction of the rare earth halide of the first group and the rare earth oxyhalide of the second group of rare earth elements by chemically reacting the mixture containing the oxides of the plurality of types of rare earth elements in the presence of a halogen source. Reaching the equilibrium state; and
Introducing the rare earth halide and the rare earth oxyhalide into water to selectively dissolve the rare earth halide in water and extracting it in a liquid phase, leaving the rare earth oxyhalide as a solid phase; and
Separating the first group of rare earth elements and the second group of rare earth elements by solid-liquid separation of the liquid phase from which the rare earth halide is extracted and the solid phase of the remaining rare earth oxyhalide. A method for separating and recovering rare earth elements, comprising: The rare earth element separation and recovery method according to claim 1 or 2,
A method for separating and recovering a rare earth element, wherein the halogen is chlorine. In the method for separating and recovering rare earth elements according to any one of claims 1 to 3,
A rare earth element separation and recovery method comprising neodymium as the first group rare earth element and dysprosium as the second group rare earth element. A method for separating and recovering multiple types of rare earth elements,
Producing a mixture containing chloride by chlorinating the compound containing the plurality of rare earth elements, iron and boron with iron chloride;
Separating the mixture of the rare earth element chlorides from the chloride-containing mixture by distillation with respect to the chloride-containing mixture;
The first group of rare earth element rare earth chlorides and the second group rare earth element rare earth oxychlorides are chemically reacted with the mixture of the rare earth element chlorides in the presence of an oxygen source. Reaching the equilibrium state; and
A step of selectively dissolving the rare earth chloride in water by extracting the rare earth chloride and the rare earth oxychloride into water and extracting the rare earth chloride in a liquid phase, and leaving the rare earth oxychloride as a solid phase; When,
Separating the first group of rare earth elements and the second group of rare earth elements by solid-liquid separation of the liquid phase from which the rare earth chloride is extracted and the remaining solid phase of the rare earth oxychloride; A method for separating and recovering rare earth elements, comprising: A method for separating and recovering multiple types of rare earth elements,
A step of performing a roasting treatment on the compound containing the plurality of rare earth elements, iron and boron;
A step of selectively leaching the plurality of rare earth elements by immersing the roasted compound in an acid;
Producing a precipitate of the plurality of rare earth elements from the acid leaching solution;
Generating a mixture of the plurality of rare earth oxides from the precipitate;
The chemical equilibrium state of the rare earth chloride of the first group rare earth and the rare earth oxychloride of the second group rare earth by chemically reacting the mixture of the plurality of rare earth oxides in the presence of a chlorine source. The process of reaching
A step of selectively dissolving the rare earth chloride in water by extracting the rare earth chloride and the rare earth oxychloride into water and extracting the rare earth chloride in a liquid phase, and leaving the rare earth oxychloride as a solid phase; When,
Separating the first group of rare earth elements and the second group of rare earth elements by solid-liquid separation of the liquid phase from which the rare earth chloride is extracted and the remaining solid phase of the rare earth oxychloride; A method for separating and recovering rare earth elements, comprising: In the method for separating and recovering rare earth elements according to claim 5 or 6,
A method for separating and recovering rare earth elements, comprising neodymium and dysprosium as the plurality of rare earth elements. In the method for separating and recovering rare earth elements according to any one of claims 5 to 7,
A method for separating and recovering a rare earth element, wherein the rare earth chloride is neodymium chloride, and the rare earth oxychloride is dysprosium oxychloride.

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