WO2017170347A1 - DyとTbを含む合金から両者を分離する方法 - Google Patents
DyとTbを含む合金から両者を分離する方法 Download PDFInfo
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- WO2017170347A1 WO2017170347A1 PCT/JP2017/012292 JP2017012292W WO2017170347A1 WO 2017170347 A1 WO2017170347 A1 WO 2017170347A1 JP 2017012292 W JP2017012292 W JP 2017012292W WO 2017170347 A1 WO2017170347 A1 WO 2017170347A1
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Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B59/00—Obtaining rare earth metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B3/00—Destroying solid waste or transforming solid waste into something useful or harmless
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B09—DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
- B09B—DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- B09B5/00—Operations not covered by a single other subclass or by a single other group in this subclass
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
- C22B7/001—Dry processes
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/04—Refining by applying a vacuum
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Definitions
- the present invention relates to a method of separating both from an alloy containing heavy rare earth elements Dy and Tb as constituent metals.
- R—Fe—B permanent magnets R is a rare earth element
- R-Fe-B permanent magnet production plants produce a large amount of magnets every day, but due to an increase in the production of magnets, processing defects etc. during the manufacturing process.
- the amount of magnet scrap discharged as magnets and magnet processed scraps discharged as cutting scraps, grinding scraps, and the like is also increasing.
- the processing yield ratio tends to increase and the manufacturing yield tends to decrease year by year.
- Patent Document 1 proposes a method in which a rare earth element is separated from an iron group element as an oxide and recovered by being transferred to the presence and heat-treated at a temperature of 1150 ° C. or higher.
- Patent Document 1 The above method proposed in Patent Document 1 is excellent as a recycling system that requires low cost and simplicity, but the object to be treated is derived from, for example, R—Fe—B permanent magnets having different compositions.
- the rare earth oxides separated and recovered from the iron group elements are usually mixed with light rare earth elements and heavy rare earth elements. It is a complex oxide or a mixture of oxides of rare earth elements.
- a mixture of a light rare earth element and a heavy rare earth element composite oxide or oxide is separated into light rare earth element ions and heavy rare earth element ions by, for example, subjecting to a solvent extraction method proposed in Patent Document 2,
- Light rare earth metals and heavy rare earth metals can be recovered by converting each to oxides and fluorides and then subjecting them to a molten salt electrolysis method and a Ca reduction method.
- the recovered heavy rare earth metal is an alloy containing Dy and Tb as constituent metals. Separation of both from an alloy containing Dy and Tb can also be achieved by, for example, subjecting to a solvent extraction method.
- a large facility is required. , Requires a large amount of extractant and organic solvent.
- an object of the present invention is to provide a method for separating both from an alloy containing Dy and Tb as constituent metals without using a solvent extraction method.
- the method of separating both from an alloy containing Dy and Tb as constituent metals of the present invention based on the above knowledge is as follows.
- the composition of Dy and Tb in the alloy is expressed as Dy x Tb y (atomic composition). Ratio), when the heat treatment temperature is t, the vapor pressure of Dy alone at the temperature t is Pt Dy (Pa), the vapor pressure of Tb alone at the temperature t is Pt Tb (Pa), and the equation 1: Pt Tb ⁇ Pt ⁇ It is characterized by vaporizing Dy by heat-treating the alloy in an atmosphere of pressure Pt (Pa) satisfying Pt Dy ⁇ (x / (x + y)).
- the method according to claim 2 is characterized in that, in the method according to claim 1, the heat treatment temperature t is set to 900 ° C. to 1500 ° C.
- a method according to claim 3 is characterized in that in the method according to claim 1, Dy is vaporized from the alloy until x / (x + y) becomes 0.1 or less.
- the method according to claim 4 is characterized in that in the method according to claim 1, vaporized Dy is solidified by a cooling means.
- a method according to claim 5 is characterized in that, in the method according to claim 1, vaporized Dy is captured by a getter.
- a method according to claim 6 is characterized in that, in the method according to claim 5, the material of the getter is Fe.
- the method according to claim 7 is characterized in that, in the method according to claim 1, Dy and Tb contained in the alloy are each derived from an R—Fe—B permanent magnet.
- Example 2 It is a vapor pressure curve of each metal of Mg, Ca, Dy, and Tb.
- Example 2 it is a graph which shows the relationship between Dy density
- Example 3 it is a graph which shows the difference in the effectiveness as a getter by the difference in the number of the Fe plates used as a getter, and the heat processing time with respect to Dy vaporized from the sample. It is an XRD peak pattern of the fluoride of Dy and Tb obtained in the process 4 for preparing the Dy and Tb containing alloy used as a sample in Example 5.
- the method of separating both from an alloy containing Dy and Tb as the constituent metals of the present invention is such that the composition of Dy and Tb in the alloy is Dy x Tb y (atomic composition ratio) and the heat treatment temperature is t, and Dy at temperature t
- a single vapor pressure is Pt Dy (Pa)
- a single vapor pressure of Tb at a temperature t is Pt Tb (Pa)
- a pressure Pt (Pt Tb ⁇ Pt ⁇ Pt ⁇ Pt Dy ⁇ (x / (x + y)) is satisfied. It is characterized by vaporizing Dy by heat-treating the alloy in an atmosphere of Pa).
- Dy, Tb-containing alloy An alloy containing Dy and Tb as constituent metals to which the method of the present invention can be applied (hereinafter abbreviated as “Dy, Tb-containing alloy”) is an alloy containing Dy and Tb, which are heavy rare earth elements.
- the other elements may include light rare earth elements such as Nd and Pr, iron group elements such as Fe, Co, and Ni, and boron as other elements.
- the total of the Dy content and the Tb content of the Dy, Tb-containing alloy is desirably 90% by mass or more, and more desirably 95% by mass or more.
- the total content of light rare earth elements, iron group elements, boron and the like is desirably 5.0% by mass or less, and more desirably 2.5% by mass or less.
- alloys containing Dy and Tb include R—Fe—B permanent magnets containing Nd and Pr as light rare earth elements and Dy as heavy rare earth elements, Nd and Pr as light rare earth elements and Tb as heavy rare earth elements. Examples thereof include those derived from a mixture of R—Fe—B permanent magnets.
- a Dy, Tb-containing alloy derived from such a mixture of magnets was obtained, for example, by a method proposed in Patent Document 1 from a mixture of magnets to obtain a complex oxide or oxide mixture of light rare earth elements and heavy rare earth elements. Thereafter, the obtained light rare earth element and heavy rare earth element complex oxide or mixture of oxides is subjected to a solvent extraction method proposed in Patent Document 2 to separate light rare earth element ions and heavy rare earth element ions.
- the heavy rare earth element ions separated from the light rare earth element ions can be obtained by converting them into oxides or fluorides of heavy rare earth elements and then subjecting them to a molten salt electrolysis method or a Ca reduction method.
- a heavy rare earth element ion containing Dy ions and Tb ions (hereinafter abbreviated as “Dy, Tb-containing ions”) is converted into an oxide or fluoride of Dy and Tb, and then a molten salt electrolysis method or By subjecting to a Ca reduction method, a Dy, Tb-containing alloy can be obtained.
- a method in which a Dy, Tb-containing ion is converted to a fluoride of Dy and Tb and then subjected to the Ca reduction method is adopted. Is preferred.
- the melting point of the metal Dy and the metal Tb is that the melting point of the metal Dy and the metal Tb is high at 1300 ° C. or lower. Therefore, it is desirable to use a metal that is alloyed with Dy or Tb to lower the melting point of the alloy because it is difficult to separate from CaF 2 slag produced by Ca reduction.
- Mg or Zn is used as a metal that is alloyed with Dy or Tb to lower the melting point of the alloy.
- Mg and Zn form an intermetallic compound having a melting point of 1000 ° C. or less with Dy and Tb, and also have a high vapor pressure, so even if they coexist in a Dy and Tb-containing alloy to which the method of the present invention is applied. This is because it can be easily distilled off.
- a specific method of using Mg when the Dy and Tb-containing ions are converted to fluorides of Dy and Tb and then subjected to the Ca reduction method is, for example, as follows.
- the ions containing Dy and Tb are converted to fluorides of Dy and Tb via the oxides of Dy and Tb or directly to fluorides of Dy and Tb.
- Ca and Mg are added to the obtained fluoride of Dy and Tb, and Ca reduction is performed by heat treatment at 1000 ° C. to 1100 ° C. for 30 minutes to 24 hours in an argon stream.
- the amount of Mg added it is desirable that the numerical value calculated by the formula of (Mg / (Mg + Dy and Tb)) ⁇ 100 is 30% to 70% as a molar ratio with respect to the total amount of Dy and Tb. If this value is less than 30%, the melting point of the alloy becomes 1100 ° C.
- CaCl 2 may be added for the purpose of efficiently separating the Dy, Tb-containing alloy and the CaF 2 slag by lowering the melting point of the CaF 2 slag generated by the Ca reduction. CaCl 2 is suitable as a flux that can lower the melting point of CaF 2 slag without adversely affecting Ca reduction.
- Amount of CaCl 2, compared the amount of CaF 2 on the calculation, the molar ratio is a value calculated by formula (CaCl 2 / (CaCl 2 + CaF 2)) ⁇ 100 is 40% to 80% It is desirable. If this value is less than 40%, it may not function sufficiently as a flux. On the other hand, even if this value exceeds 80%, the function as a flux is not improved and only the cost is increased.
- Mg and Ca are distilled off from the obtained alloy containing Ca and Mg based on the vapor pressure curves of the respective metals (see FIG. 1).
- a Dy, Tb-containing alloy containing Ca and Mg is heated at 800 ° C. to 1000 ° C. under a reduced pressure of 10 ⁇ 2 Pa to 100 Pa.
- Ca and Mg are distilled off to reduce 98% or more of Dy and Tb contained in the fluoride of Dy and Tb, and the Dy and Tb-containing alloy is spongy. It is obtained by.
- the sponge-like Dy, Tb-containing alloy thus obtained may be applied as it is, or may be melted in an arc melting furnace and processed into a form such as an ingot, slab or foil.
- the method may be applied.
- the method of using Zn when the Dy and Tb-containing ions are converted to fluorides of Dy and Tb and then subjected to the Ca reduction method may be based on the method of using Mg.
- the method of the present invention is, if necessary, by vaporizing only Dy by heat-treating an alloy containing Dy and Tb in an atmosphere of a pressure that vaporizes Dy but does not vaporize Tb.
- Dy and Tb are all solid solutions and do not form intermetallic compounds, and the vapor pressure of Dy is very high compared to the vapor pressure of Tb, so that only Dy is vaporized from Dy and Tb-containing alloys.
- the present inventors have found a processing condition in which Dy is vaporized but Tb is not vaporized.
- the heat treatment temperature is desirably 900 ° C. to 1500 ° C.
- the heat treatment temperature is desirably 1000 ° C. to 1300 ° C.
- Dy as the pressure that Tb is not vaporized but is Dy from Tb-containing alloy vaporizes, in the method of the present invention, the composition of Dy and Tb in the alloy Dy x Tb y (atomic composition ratio), when the heat treatment temperature was set to t, Assuming that the vapor pressure of Dy alone at temperature t is Pt Dy (Pa) and the vapor pressure of Tb alone at temperature t is Pt Tb (Pa), Equation 1: Pt Tb ⁇ Pt ⁇ Pt Dy ⁇ (x / (x + y)) A filling pressure Pt (Pa) is employed.
- the pressure Pt greater than Tb alone vapor pressure Pt Tb, and, by setting smaller than Dy x Tb y of Dy vapor pressure Pt Dy ⁇ (x / (x + y)), vaporizes only Dy alloy be able to.
- the pressure Pt at the start of processing is 8.0 ⁇ 10 ⁇ 6 if heat treatment is performed at 900 ° C. In the range of Pa to 0.05 Pa, if it is heat-treated at 1500 ° C., it is in the range of 1.1 Pa to 200 Pa.
- the pressure Pt may be gradually changed with time, but the target is achieved by evaporating only Dy from the alloy, for example, x / (x + y) ⁇ 0.1.
- the sufficient pressure Pt may be maintained without being changed from the start of processing until the target is achieved.
- the composition of Dy and Tb in the alloy to be processed is DyTb 2 and the target is x / (x + y) ⁇ 0.1, and the pressure Pt is not changed from the start of processing until the target is achieved.
- the pressure Pt is in the range of 8.0 ⁇ 10 ⁇ 6 Pa to 0.005 Pa if heat treated at 900 ° C. and in the range of 1.1 Pa to 20 Pa if heat treated at 1500 ° C. Since Pt Dy is two orders of magnitude higher than Pt Tb , it is possible to sufficiently set x / (x + y) ⁇ 0.01 if a vacuum apparatus having an excellent exhaust capability is used. Note that when a Dy, Tb-containing alloy is heat-treated in an atmosphere having a pressure that satisfies Equation 1, Tb does not vaporize theoretically, but in reality, some Tb may vaporize. Even in such a case, as long as the Dy, Tb-containing alloy is heat-treated in an atmosphere of a pressure satisfying the formula 1, it is included in the scope of the present invention, as Tb is not substantially vaporized.
- the Dy, Tb-containing alloy is, for example, housed in a crucible excellent in heat resistance and corrosiveness, or placed on a dish (the material of the crucible or dish is exemplified by Mo), and the processing chamber of the furnace In this case, heat treatment may be performed in an atmosphere of a predetermined temperature and pressure (the treatment time depends on the degree of vaporizing only Dy from the target alloy).
- the shape of the Dy, Tb-containing alloy is sponge, foil, or granular or powdery with a particle size of 1 mm or less, and because of the large surface area, only Dy can be effectively vaporized from the alloy. Is desirable.
- the crucible containing the Dy, Tb-containing alloy may be further heat-treated by being housed in a container (such as a Mo pack) having excellent heat resistance and corrosion resistance. Control the rate of diffusion of vaporized Dy into the processing chamber of the furnace by opening the container completely, partially opening it, or closing it after communicating with the outside. be able to.
- a container such as a Mo pack
- Dy vaporized from the Dy, Tb-containing alloy can be recovered by solidifying by a cooling means. If only Dy is vaporized from the alloy, the purity of Tb in the alloy increases. In order to maintain the pressure in the furnace processing chamber at the pressure Pt, it is of course important to recover the vaporized Dy from the alloy in order to reuse the Dy contained in the alloy. It is also important. If the vaporized Dy is not recovered from the alloy, the vaporized Dy stays in the processing chamber. As a result, the pressure in the processing chamber becomes the pressure obtained by adding the vapor pressure of the vaporized Dy to the pressure Pt, and the Dy is prevented from vaporizing. work.
- a Dy, Tb-containing alloy is heat-treated in the vicinity of one end in the processing chamber of the tubular furnace, and an exhaust means such as a rotary pump is provided at the other end, and the vicinity thereof is cooled by water cooling from the outside.
- Dy vaporized from the alloy can be recovered by solidifying (see, for example, JP-A-2001-303149, if necessary).
- the temperature and pressure adopted for heat-treating the Dy, Tb-containing alloy mean the temperature and pressure around the alloy (that is, soaking zone) (because the temperature and pressure in the processing chamber differ depending on the location).
- the recovered Dy can be reused by a desired method after being purified as necessary.
- Dy vaporized from the Dy, Tb-containing alloy may be recovered by being captured by a getter.
- the material of the getter Fe is desirable in that vaporized Dy can be effectively captured.
- Dy vaporized from the alloy is captured by a getter made of Fe, Dy is recovered as an alloy with Fe.
- the shape of the getter may be a plate shape or the like, but it is desirable that the getter is in the form of particles or powder having a particle size of 1 mm or less because Dy can be effectively captured due to the large surface area.
- the Dy trapping efficiency by the getter and the composition of Dy and Fe in the alloy can be changed.
- the alloy of Dy and Fe may be reused as it is as a raw material for producing an R—Fe—B permanent magnet, or separated from Fe by subjecting it to a solvent extraction method, for example.
- Dy can be reused by a desired method after purification as necessary.
- the alloy after only Dy is vaporized from the alloy containing Dy and Tb may be reused as it is as an alloy with increased Tb purity.
- only Dy is vaporized by the method of the present invention to increase the purity of Tb. It may be higher.
- Example 1 A DyTb 2 alloy foil having a width of 2 to 3 mm and a thickness of 20 to 100 ⁇ m prepared by a single roll liquid quenching method (atomic composition ratio (Tb / Dy) is 1.8 to 1.9 according to EDX analysis) According to ICP analysis, it was 1.93, Dy concentration by EDX analysis was 30.7% by mass, and Tb concentration was 56.3% by mass) to a length of 15 mm or less and weighed 2.05 g. The sample was placed on a Mo dish having a length of 30 mm and a width of 30 mm.
- the heat treatment environment was such that the pressure in the processing chamber was evacuated to 5.0 ⁇ 10 ⁇ 3 Pa or less, the temperature was raised to 600 ° C. at 10 ° C./min, held at 600 ° C. for 1 hour, and then further 5 ° It was formed by heating up to 1100 ° C. at / min. After 2 hours, the processing chamber was cooled to room temperature under vacuum and returned to normal pressure, and then the dish on which the sample was placed was taken out from the tubular furnace. When the mass of the dish on which the sample after heat treatment was placed was measured, it was reduced by 0.14 g from before the heat treatment.
- Example 2 Same as Example 1 except that the vaporized Dy stays in the Mo pack, so that the niobium foil is not bitten and the opening of the pack is not completely covered without being covered.
- the mass of the sample after the heat treatment decreased as the heat treatment time increased.
- FIG. 2 shows the results (mass%) of the Dy concentration and the Tb concentration of the residual sample in the crucible when the heat treatment time is 10 minutes, 30 minutes, 2 hours, and 4 hours, respectively, by EDX analysis.
- the Dy concentration decreased and the Tb concentration increased as the amount of Dy vaporized from the sample increased as the heat treatment time increased.
- Example 3 As a getter, an Fe plate of length: 50 mm ⁇ width: 35 mm ⁇ thickness: 0.2 mm, or an Fe plate of length: 50 mm ⁇ width: 50 mm ⁇ thickness: 0.2 mm, one piece in the Mo pack or Except that multiple sheets are accommodated (when multiple sheets are accommodated, they are not accommodated in an overlapping manner), heat treatment is performed in the same manner as in Example 1, and the amount of Dy evaporation from the sample under various conditions (sample after heat treatment) The amount of increase in the mass of the Fe plate after heat treatment.
- the Dy adsorption rate (%) calculated by the equation of Dy adhesion amount / Dy evaporation amount from sample) ⁇ 100 was examined (assuming that vaporization from the sample is only Dy). The results are shown in FIG. As is clear from FIG. 3, the more the number of Fe plates accommodated in the Mo pack and the longer the heat treatment time, the more the amount of Dy evaporated from the sample and the amount of Dy attached to the Fe plate increase, 70% The above Dy adsorption rate could be achieved (when the surface composition of the Fe plate was analyzed by EDX, Dy was 25 atm% to 30 atm%, whereas Tb was 1 atm% to 2 atm%.
- the Dy evaporation rate (%) calculated by the formula of (Dy evaporation amount from sample / Dy amount contained in sample) ⁇ 100 is 90. %).
- the difference in the results due to the difference in the size of the Fe plate is not shown in FIG. 3, the larger the size of the Fe plate, the more the amount of Dy evaporated from the sample, the amount of Dy attached to the Fe plate, and the Dy adsorption rate. It was found from another experiment that the numbers were all high.
- Example 4 As a getter, bulk density: about 2.0 g / cm 3, specific surface area: 0.5m 2 /g ⁇ 1.0m 2 / g, particle size: 53 .mu.m or less of electrolytic iron powder A, or bulk density: about 2. 5 g / cm 3 , specific surface area: 0.094 m 2 / g, particle size: 2 ⁇ g or 3 g of electrolytic iron powder B having a particle size of 150 ⁇ m or less, length: 30 mm ⁇ width: 30 mm on a Mo dish, or Length: 40 mm x width: 40 mm. Mounted on a Mo dish, and contained one or more dishes on which electrolytic iron powder is placed in a Mo pack.
- Heat treatment was performed in the same manner as in Example 1 except that the heat treatment was performed for 8 hours.
- Dy evaporation from sample decrease in mass of sample after heat treatment
- Dy adherence to electrolytic iron powder increase in mass of electrolytic iron powder after heat treatment. Multiple plates on which electrolytic iron powder is placed When stored, the total amount of individual increases
- Dy adhesion amount to electrolytic iron powder / Dy evaporation amount from sample ⁇ Dy adsorption rate (%) calculated by the formula of 100
- (from sample Dy evaporation amount / Dy amount contained in sample) ⁇ Dy evaporation rate (%) calculated by a mathematical formula of 100 was examined (assuming vaporization from the sample is only Dy).
- Table 1 shows the results of the Dy adsorption rate and the Dy evaporation rate.
- Table 1 shows the results of the Dy adsorption rate and the Dy evaporation rate.
- the Dy adsorption rate and the Dy evaporation rate increase, and both achieve 90% or more.
- the Dy concentration and the Tb concentration of the sample after the heat treatment decreased as compared with each of the samples before the heat treatment, and the Tb concentration increased (see Table 1).
- Example 5 A: Preparation of a Dy, Tb-containing alloy used as a sample to which the method of the present invention is applied
- An R—Fe—B permanent magnet containing Nd, Pr as a light rare earth element and Dy as a heavy rare earth element, and Nd, as a light rare earth element Using an R—Fe—B permanent magnet containing Pr and Tb as a heavy rare earth element, it was prepared as follows.
- (Process 1) According to the method proposed in Patent Document 1, suction filtration is performed on magnet processing waste (stored in water for 7 days to prevent spontaneous ignition) generated in each manufacturing process and having a particle size of about 10 ⁇ m. Then, it was dehydrated and burned using a rotary kiln to oxidize.
- the mixture of magnetized scraps subjected to oxidation treatment was accommodated in a carbon crucible (made of graphite), and then heat treated at 1450 ° C. for 1 hour in an argon gas stream using an electric furnace. Thereafter, heating in the furnace is stopped, and the carbon crucible is cooled to room temperature while maintaining the argon gas atmosphere in the furnace, so that light rare earth elements (Nd, Pr) and heavy rare earth elements (Dy, Tb) are cooled.
- a complex oxide or a mixture of oxides was obtained as one of two lumps that existed independently and closely.
- the light rare earth element-heavy rare earth element complex oxide or oxide mixture obtained in step 1 was pulverized with a smoked mortar and pestle, and a powder having a particle size of less than 125 ⁇ m was obtained using a stainless steel sieve. .
- the obtained powder was dissolved in hydrochloric acid, and the residue was filtered to obtain a hydrochloric acid solution of light rare earth elements and heavy rare earth elements.
- the obtained light rare earth element and heavy rare earth element hydrochloric acid solution was subjected to the solvent extraction method proposed in Patent Document 2 to separate light rare earth element ions and heavy rare earth element ions.
- Oxalic acid dihydrate was added to the resulting hydrochloric acid solution of heavy rare earth element to obtain heavy rare earth element oxalate as powder.
- the heavy rare earth element oxalate obtained in step 3 was placed in an alumina crucible and fired in an air atmosphere to obtain a complex oxide or oxide mixture of heavy rare earth elements.
- the titanium crucible containing the above mixture was accommodated in an iron crucible (outer diameter: 39 mm ⁇ inner diameter: 33 mm ⁇ height: 70 mm, material: SS400), and a titanium crucible was accommodated.
- the iron crucible was sealed by screwing with an iron lid of outer diameter: 45 mm ⁇ inner diameter: 39 mm ⁇ height: 10 mm.
- the iron crucible sealed inside was taken out from the glove box in an argon gas atmosphere, and the main body and the lid were welded, and then heat-treated at 1100 ° C. for 1 hour in an argon gas stream using an electric furnace. Thereafter, the heating in the furnace was stopped, the iron crucible was cooled to room temperature while maintaining the argon gas atmosphere in the furnace, and then the iron crucible was taken out. The iron crucible was cut, the titanium crucible was taken out, and the contents were collected. The contents of the recovered titanium crucible were a CaF 2 slag at the upper part and a Ca-reduced metal at the lower part, and both were present independently and closely.
- the upper CaF 2 slag was easily detached from the lower Ca-reduced metal by applying a physical impact.
- Dy and Tb were not detected from CaF 2 slag (by fluorescent X-ray analysis).
- the Ca-reduced metal contained 29.9 atm% Dy, 2.1 atm% Tb, 2.1 atm% Ca, 55.1 atm% Mg, and 6.6 atm% O (according to EDX analysis). .
- the Ca reduced metal was heat treated at 1000 ° C. for 24 hours under a reduced pressure of 0.1 Pa in a heat treatment furnace equipped with a heating part and a cooling part for capturing and recovering vapors of Mg and Ca.
- a Dy, Tb-containing alloy used as a sample to which the method of the present invention was applied was obtained.
- Example 6 A Ca-reduced metal was obtained in the same manner as in Example 5 except that the amount of metal Ca used in Step 5 for preparing the Dy, Tb-containing alloy of Example 5 was changed to 3.13 g.
- the resulting Ca-reduced metal contained 30.2 atm% Dy, 2.4 atm% Tb, 16.4 atm% Ca, 41.5 atm% Mg, and 9.1 atm% O (EDX By analysis).
- EDX EDX By analysis.
- a Dy, Tb-containing alloy used as a sample to which the method of the present invention was applied was obtained.
- Tb 92.6: 7.4
- EDX analysis EDX analysis.
- 10 g of this Dy, Tb-containing alloy was used as a sample to which the method of the present invention was applied and heat-treated in the same manner as in Example 5, (Dy adhesion amount to electrolytic iron powder / Dy evaporation amount from sample) ⁇ 100
- the Dy adsorption rate calculated by the mathematical formula was 90% or more (assuming that vaporization from the sample is only Dy), and the Tb concentration of the sample after the heat treatment was 90% by mass or more (according to EDX analysis). From the above results, it was found that the method of the present invention was able to effectively separate both from the Dy, Tb-containing alloy.
- Example 7 In step 5 for preparing the Dy, Tb-containing alloy of Example 5, the amount of metal Ca used was 2.04 g, the amount of metal Mg used was 0.270 g (molar ratio to the total amount of Dy and Tb) The metal reduced by Ca in the same manner as in Example 5 except that (the numerical value calculated by the mathematical formula of (Mg / (Mg + Dy and Tb)) ⁇ 100 corresponds to the addition amount of 30.0%) Obtained.
- the obtained Ca-reduced metal contained 44.4 atm% Dy, 3.2 atm% Tb, 3.5 atm% Ca, 28.6 atm% Mg, and 10.0 atm% O (EDX). By analysis).
- Example 5 by distilling off Ca and Mg from the Ca-reduced metal in the same manner as in Example 5, a Dy, Tb-containing alloy used as a sample to which the method of the present invention was applied was obtained.
- Example 8 In Step 5 for preparing the Dy, Tb-containing alloy of Example 5, the amount of metal Mg used was 0.940 g (Mg / (Mg + Dy and Tb) as a molar ratio with respect to the total amount of Dy and Tb). ) A metal reduced with Ca was obtained in the same manner as in Example 5 except that the numerical value calculated by the mathematical formula of x100 corresponds to the addition amount of 60.0%). The resulting Ca-reduced metal contained 29.1 atm% Dy, 1.8 atm% Tb, 10.0 atm% Ca, 52.0 atm% Mg, and 7.1 atm% O (EDX By analysis).
- Example 5 by distilling off Ca and Mg from the Ca-reduced metal in the same manner as in Example 5, a Dy, Tb-containing alloy used as a sample to which the method of the present invention was applied was obtained.
- Example 9 In Step 5 for preparing the Dy, Tb-containing alloy of Example 5, the amount of metal Ca used is 2.04 g, the amount of metal Mg used is 0.660 g (molar ratio with respect to the total amount of Dy and Tb) (The numerical value calculated by the formula of (Mg / (Mg + Dy and Tb)) ⁇ 100 corresponds to the addition amount of 51.0%), and the usage amount of CaCl 2 is 2.90 g (calculated amount of CaF 2 generated) On the other hand, the method is the same as that of Example 5 except that the molar ratio is (CaCl 2 / (CaCl 2 + CaF 2 )) ⁇ 100. The metal reduced by Ca was obtained.
- the obtained Ca-reduced metal had 28.9 atm% Dy, 2.0 atm% Tb, 10.5 atm% Ca, 49.4 atm% Mg, 9.0 atm% O, 0.1 atm F. % (By EDX analysis).
- a Dy, Tb-containing alloy used as a sample to which the method of the present invention was applied was obtained.
- Reference example 1 When heat treatment was performed for 2 hours in the same manner as in Example 1 using a DyFe 2 alloy slab instead of the DyTb 2 alloy foil as a treatment target, and the mass of the sample after the heat treatment was measured, only 0.01 g from before the heat treatment was measured. It did not decrease. This result means that it is difficult to separate both from an alloy containing Dy and Fe as constituent metals by heat treatment, and that Fe is excellent as a getter material for vaporized Dy.
- the present invention has industrial applicability in that it can provide a method for separating both from an alloy containing Dy and Tb without using a solvent extraction method.
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Abstract
Description
また、請求項2記載の方法は、請求項1記載の方法において、熱処理温度tを900℃~1500℃とすることを特徴とする。
また、請求項3記載の方法は、請求項1記載の方法において、x/(x+y)が0.1以下になるまで合金からDyを気化させることを特徴とする。
また、請求項4記載の方法は、請求項1記載の方法において、気化したDyを冷却手段によって固化させることを特徴とする。
また、請求項5記載の方法は、請求項1記載の方法において、気化したDyをゲッターに捕捉させることを特徴とする。
また、請求項6記載の方法は、請求項5記載の方法において、ゲッターの材質がFeであることを特徴とする。
また、請求項7記載の方法は、請求項1記載の方法において、合金に含まれるDyとTbが、それぞれR-Fe-B系永久磁石に由来するものであることを特徴とする。
単ロール液体急冷法により作製した、幅が2mm~3mmで厚さが20μm~100μmのDyTb2合金箔体(原子組成比(Tb/Dy)はEDX分析によれば1.8~1.9であってICP分析によれば1.93。EDX分析によるDy濃度は30.7質量%であってTb濃度は56.3質量%)を、長さ15mm以下に裁断し、2.05g量りとって、縦:30mm×横:30mmのMo製の皿の上に試料として載置した。この合金を載置した皿を、縦:200mm×横:75mm×高さ:40mmのMoパックに収容し、外部との連通を図りつつもできるだけ密閉するためにニオブ箔を間にかませて蓋をしてから、管状炉(光洋サーモシステム社製)の処理室内で、1100℃において、5.0×10-3Pa以下の圧力(式1における圧力Pt(t=1100℃))下で2時間熱処理した(熱処理温度が1100℃の場合の処理開始時における圧力Ptの上限は0.3Paであって下限は1.2×10-3Pa)。熱処理の環境は、処理室内の圧力が5.0×10-3Pa以下になるまで排気した後、10℃/minで600℃まで昇温し、600℃で1時間保持した後、さらに5℃/minで1100℃まで昇温することで形成した。2時間後、処理室内を真空下で室温まで炉冷し、常圧に復圧した後、管状炉から試料を載置した皿を取り出した。熱処理後の試料を載置した皿の質量を測定したところ、熱処理前から0.14g減少していた。皿の上の残留試料のDy濃度とTb濃度をEDX分析によって測定したところ、Dy濃度は25.1質量%であってTb濃度は65.1質量%であり、試料からDyが気化したことで、Dy濃度が減少し、Tb濃度は増加した。以上の結果から、本発明の方法によれば、Dy,Tb含有合金から両者を熱処理によって分離することができることがわかった。
Moパック内に気化したDyが滞留することを回避するため、ニオブ箔をかませることなく、かつ、パックの開口を完全に蓋をせずに一部を開放すること以外は実施例1と同様の方法で熱処理したところ、熱処理時間が長くなるにつれて熱処理後の試料の質量は減少した。熱処理時間が10分間、30分間、2時間、4時間のそれぞれの場合における坩堝内の残留試料のDy濃度とTb濃度をEDX分析によって測定した結果(質量%)を図2に示す。図2から明らかなように、熱処理時間が長くなるにつれて試料からのDyの気化量が増加することで、Dy濃度が減少し、Tb濃度は増加した。
ゲッターとして、縦:50mm×横:35mm×厚さ:0.2mmのFe板、または、縦:50mm×横:50mm×厚さ:0.2mmのFe板を、Moパック内に、1枚または複数枚収容する(複数枚収容する場合は重ねて収容しない)こと以外は実施例1と同様の方法で熱処理し、各種の条件のもとでの、試料からのDy蒸発量(熱処理後の試料の質量の減少量)、Fe板へのDy付着量(熱処理後のFe板の質量の増加量。Fe板を複数枚収容した場合には個々の増加量の合計量)、(Fe板へのDy付着量/試料からのDy蒸発量)×100の数式で算出されるDy吸着率(%)を調べた(試料からの気化はDyのみと仮定)。結果を図3に示す。図3から明らかなように、Moパック内に収容したFe板の枚数が多いほど、また、熱処理時間が長いほど、試料からのDy蒸発量とFe板へのDy付着量が増加し、70%以上のDy吸着率を達成することができた(Fe板の表面組成をEDX分析すると、Dyは25atm%~30atm%であるのに対し、Tbは1atm%~2atm%であることから、試料から気化しているのはほぼDyのみである。上記の仮定に従えば、(試料からのDy蒸発量/試料に含まれるDy量)×100の数式で算出されるDy蒸発率(%)は90%に達する)。なお、図3ではFe板の大きさの違いによる結果の違いは示していないが、Fe板の大きさが大きいほど、試料からのDy蒸発量、Fe板へのDy付着量、Dy吸着率のすべてにおいて数値が大きいことが別の実験からわかった。
ゲッターとして、かさ密度:約2.0g/cm3、比表面積:0.5m2/g~1.0m2/g、粒径:53μm以下の電解鉄粉A、または、かさ密度:約2.5g/cm3、比表面積:0.094m2/g、粒径:150μm以下の電解鉄粉Bを、2gまたは3g量りとり、縦:30mm×横:30mmのMo製の皿の上、または、縦:40mm×横:40mmのMo製の皿の上に載置して用いたことと、Moパック内に、電解鉄粉を載置した皿を1枚または複数枚収容して、1100℃で8時間熱処理すること以外は実施例1と同様の方法で熱処理した。試料からのDy蒸発量(熱処理後の試料の質量の減少量)、電解鉄粉へのDy付着量(熱処理後の電解鉄粉の質量の増加量。電解鉄粉を載置した皿を複数枚収容した場合には個々の増加量の合計量)、(電解鉄粉へのDy付着量/試料からのDy蒸発量)×100の数式で算出されるDy吸着率(%)、(試料からのDy蒸発量/試料に含まれるDy量)×100の数式で算出されるDy蒸発率(%)を調べた(試料からの気化はDyのみと仮定)。Dy吸着率とDy蒸発率の結果を表1に示す。表1から明らかなように、Moパック内に収容した電解鉄粉の量が多いほど、即ち、ゲッターの表面積が大きいほど、Dy吸着率もDy蒸発率も増加し、いずれも90%以上を達成することができた。このことは、熱処理後の試料のDy濃度とTb濃度が、熱処理前の試料のそれぞれと比較して、Dy濃度が減少し、Tb濃度が増加したことからも裏付けられた(表1参照)。
A:本発明の方法を適用する試料として用いるDy,Tb含有合金の調製
軽希土類元素としてNd,Prと重希土類元素としてDyを含むR-Fe-B系永久磁石と、軽希土類元素としてNd,Prと重希土類元素としてTbを含むR-Fe-B系永久磁石を用いて以下のようにして調製した。
(工程1)
特許文献1において提案されている方法に従って、それぞれの製造工程中に発生した約10μmの粒径を有する磁石加工屑(自然発火防止のため水中で7日間保管したもの)に対し、吸引ろ過することで脱水してからロータリーキルンを用いて燃焼処理することで酸化処理を行った。次に、酸化処理を行った磁石加工屑の混合物を炭素るつぼ(黒鉛製)に収容した後、電気炉を用い、アルゴンガス気流中で1450℃で1時間熱処理した。その後、炉内の加熱を停止し、炉内のアルゴンガス雰囲気を維持したまま、炭素るつぼを室温まで炉冷することで、軽希土類元素(Nd,Pr)と重希土類元素(Dy,Tb)の複合酸化物ないし酸化物の混合物を、互いに独立かつ密接して存在する2種類の塊状物の一方として得た。
(工程2)
工程1で得た軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を、瑪瑙製の乳鉢と乳棒で粉砕し、ステンレス製の篩を用いて粒径が125μm未満の粉末を得た。得られた粉末を塩酸に溶解し、残渣をろ過することで、軽希土類元素と重希土類元素の塩酸溶液を得た。得られた軽希土類元素と重希土類元素の塩酸溶液を、特許文献2において提案されている溶媒抽出法に付することで、軽希土類元素イオンと重希土類元素イオンを分離した。得られた重希土類元素の塩酸溶液に、シュウ酸二水和物を加え、重希土類元素のシュウ酸塩を粉末として得た。
(工程3)
工程3で得た重希土類元素のシュウ酸塩を、アルミナるつぼに収容し、大気雰囲気中で焼成することで、重希土類元素の複合酸化物ないし酸化物の混合物を得た。得られた重希土類元素の複合酸化物ないし酸化物の混合物は、DyとTbをDy:Tb=95.6:4.4(atm%)の割合で含んでいた(蛍光X線分析による)。
(工程4)
工程3で得たDyとTbの複合酸化物ないし酸化物の混合物を塩酸に溶解した後、フッ化水素酸を加えることで生成した沈殿物を、ろ取した後、乾燥し、DyとTbのフッ化物を粉末として得た。得られたDyとTbのフッ化物は、DyとTbをDy:Tb=95.7:4.3(atm%)の割合で含んでいた(蛍光X線分析による)。また、得られたDyとTbのフッ化物に含まれるCは0.01質量%、Nは0.03質量%、Oは1.20質量%であった(ガス分析による)。得られたDyとTbのフッ化物の相関係をXRD分析によって確認したところ,標準試料として用いたDyF3およびTbF3と同様のピークパターンを有しており、a=6.45Å、b=6.92Å、c=4.01Åの斜方晶で、ほぼ単相であった(図4)。
(工程5)
工程4で得たDyとTbのフッ化物5.70gに、1.72gの顆粒の金属Ca、0.635gのワイヤーカットした金属Mg(DyおよびTbの合計量に対し、モル比として、(Mg/(Mg+DyおよびTb))×100の数式で算出される数値が50.0%の添加量に相当)、9.94gのCaCl2(計算上のCaF2の生成量に対し、モル比として、(CaCl2/(CaCl2+CaF2))×100の数式で算出される数値が70.0%の添加量に相当)を、アルゴンガス雰囲気下のグローブボックス内で混合した後、チタンるつぼ(外径:31mm×内径:29mm×高さ:60mm)に収容した。アルゴンガス雰囲気下のグローブボックス内で、上記の混合物を収容したチタンるつぼを、鉄るつぼ(外径:39mm×内径:33mm×高さ:70mm、材質:SS400)に収容し、チタンるつぼを収容した鉄るつぼを、外径:45mm×内径:39mm×高さ:10mmの鉄ふたでねじ締めして密閉した。なお、チタンるつぼを鉄るつぼに収容する際、チタンるつぼの外面が鉄るつぼの内面に接触することによる両方または一方のるつぼの溶融や破損を防止するために、チタンるつぼの外周面と底面をニオブ箔で包んだ。内部を密閉した鉄るつぼを、アルゴンガス雰囲気下のグローブボックス内から取り出し、本体と蓋を溶接した後、電気炉を用い、アルゴンガス気流中で1100℃で1時間熱処理した。その後、炉内の加熱を停止し、炉内のアルゴンガス雰囲気を維持したまま、鉄るつぼを室温まで炉冷してから、鉄るつぼを取り出した。鉄るつぼを切断してチタンるつぼを取り出し、その内容物を回収した。回収されたチタンるつぼの内容物は、上部にCaF2スラグ、下部にCa還元された金属であり、両者は互いに独立かつ密接して存在していた。上部のCaF2スラグは、物理的な衝撃を加えることで容易に下部のCa還元された金属から剥離した。CaF2スラグからはDyとTbは検出されなかった(蛍光X線分析による)。Ca還元された金属は、Dyを29.9atm%、Tbを2.1atm%、Caを2.1atm%、Mgを55.1atm%、Oを6.6atm%を含んでいた(EDX分析による)。Ca還元された金属を、加熱部と、MgとCaの蒸気を捕捉して回収する冷却部を備えた熱処理炉で、0.1Paの減圧下、1000℃で24時間熱処理し、CaとMgを蒸留除去することにより、本発明の方法を適用する試料として用いるDy,Tb含有合金を得た。得られたDy,Tb含有合金は、DyとTbをDy:Tb=93.3:6.7(atm%)の割合で含んでいた(EDX分析による)。
上記の方法で得たDy,Tb含有合金10gを本発明の方法を適用する試料とし、実施例4の実験4の条件に準じて熱処理したところ、(電解鉄粉へのDy付着量/試料からのDy蒸発量)×100の数式で算出されるDy吸着率は90%以上であり(試料からの気化はDyのみと仮定)、熱処理後の試料のTb濃度は90質量%以上であった(EDX分析による)。以上の結果から、本発明の方法によって、Dy,Tb含有合金から両者を効果的に分離することができたことがわかった。
実施例5の、Dy,Tb含有合金を調製するための工程5における、金属Caの使用量を3.13gにすること以外は実施例5と同様の方法でCa還元された金属を得た。得られたCa還元された金属は、Dyを30.2atm%、Tbを2.4atm%、Caを16.4atm%、Mgを41.5atm%、Oを9.1atm%を含んでいた(EDX分析による)。次に、Ca還元された金属から、実施例5と同様の方法でCaとMgを蒸留除去することにより、本発明の方法を適用する試料として用いるDy,Tb含有合金を得た。得られたDy,Tb含有合金は、DyとTbをDy:Tb=92.6:7.4(atm%)の割合で含んでいた(EDX分析による)。このDy,Tb含有合金10gを本発明の方法を適用する試料とし、実施例5と同様の方法で熱処理したところ、(電解鉄粉へのDy付着量/試料からのDy蒸発量)×100の数式で算出されるDy吸着率は90%以上であり(試料からの気化はDyのみと仮定)、熱処理後の試料のTb濃度は90質量%以上であった(EDX分析による)。以上の結果から、本発明の方法によって、Dy,Tb含有合金から両者を効果的に分離することができたことがわかった。
実施例5の、Dy,Tb含有合金を調製するための工程5における、金属Caの使用量を2.04g、金属Mgの使用量を0.270g(DyおよびTbの合計量に対し、モル比として、(Mg/(Mg+DyおよびTb))×100の数式で算出される数値が30.0%の添加量に相当)にすること以外は実施例5と同様の方法でCa還元された金属を得た。得られたCa還元された金属は、Dyを44.4atm%、Tbを3.2atm%、Caを3.5atm%、Mgを28.6atm%、Oを10.0atm%を含んでいた(EDX分析による)。次に、Ca還元された金属から、実施例5と同様の方法でCaとMgを蒸留除去することにより、本発明の方法を適用する試料として用いるDy,Tb含有合金を得た。得られたDy,Tb含有合金は、DyとTbをDy:Tb=93.3:6.7(atm%)の割合で含んでいた(EDX分析による)。このDy,Tb含有合金10gを本発明の方法を適用する試料とし、実施例5と同様の方法で熱処理したところ、(電解鉄粉へのDy付着量/試料からのDy蒸発量)×100の数式で算出されるDy吸着率は90%以上であり(試料からの気化はDyのみと仮定)、熱処理後の試料のTb濃度は90質量%以上であった(EDX分析による)。以上の結果から、本発明の方法によって、Dy,Tb含有合金から両者を効果的に分離することができたことがわかった。
実施例5の、Dy,Tb含有合金を調製するための工程5における、金属Mgの使用量を0.940g(DyおよびTbの合計量に対し、モル比として、(Mg/(Mg+DyおよびTb))×100の数式で算出される数値が60.0%の添加量に相当)にすること以外は実施例5と同様の方法でCa還元された金属を得た。得られたCa還元された金属は、Dyを29.1atm%、Tbを1.8atm%、Caを10.0atm%、Mgを52.0atm%、Oを7.1atm%を含んでいた(EDX分析による)。次に、Ca還元された金属から、実施例5と同様の方法でCaとMgを蒸留除去することにより、本発明の方法を適用する試料として用いるDy,Tb含有合金を得た。得られたDy,Tb含有合金は、DyとTbをDy:Tb=94.2:5.8(atm%)の割合で含んでいた(EDX分析による)。このDy,Tb含有合金10gを本発明の方法を適用する試料とし、実施例5と同様の方法で熱処理したところ、(電解鉄粉へのDy付着量/試料からのDy蒸発量)×100の数式で算出されるDy吸着率は90%以上であり(試料からの気化はDyのみと仮定)、熱処理後の試料のTb濃度は90質量%以上であった(EDX分析による)。以上の結果から、本発明の方法によって、Dy,Tb含有合金から両者を効果的に分離することができたことがわかった。
実施例5の、Dy,Tb含有合金を調製するための工程5における、金属Caの使用量を2.04g、金属Mgの使用量を0.660g(DyおよびTbの合計量に対し、モル比として、(Mg/(Mg+DyおよびTb))×100の数式で算出される数値が51.0%の添加量に相当)、CaCl2の使用量を2.90g(計算上のCaF2の生成量に対し、モル比として、(CaCl2/(CaCl2+CaF2))×100の数式で算出される数値が40.0%の添加量に相当)にすること以外は実施例5と同様の方法でCa還元された金属を得た。得られたCa還元された金属は、Dyを28.9atm%、Tbを2.0atm%、Caを10.5atm%、Mgを49.4atm%、Oを9.0atm%、Fを0.1atm%を含んでいた(EDX分析による)。次に、Ca還元された金属から、実施例5と同様の方法でCaとMgを蒸留除去することにより、本発明の方法を適用する試料として用いるDy,Tb含有合金を得た。得られたDy,Tb含有合金は、DyとTbをDy:Tb=93.5:6.5(atm%)の割合で含んでいた(EDX分析による)。このDy,Tb含有合金10gを本発明の方法を適用する試料とし、実施例5と同様の方法で熱処理したところ、(電解鉄粉へのDy付着量/試料からのDy蒸発量)×100の数式で算出されるDy吸着率は90%以上であり(試料からの気化はDyのみと仮定)、熱処理後の試料のTb濃度は90質量%以上であった(EDX分析による)。以上の結果から、本発明の方法によって、Dy,Tb含有合金から両者を効果的に分離することができたことがわかった。
DyTb2合金箔体のかわりにDyFe2合金鋳片を処理対象物として実施例1と同様の方法で熱処理を2時間行い、熱処理後の試料の質量を測定したところ、熱処理前から0.01gしか減少していなかった。この結果は、構成金属としてDyとFeを含む合金から両者を熱処理によって分離することは困難であることを意味するとともに、気化したDyに対するゲッターの材質としてFeが優れていることを意味する。
Claims (7)
- 構成金属としてDyとTbを含む合金から両者を分離する方法であって、合金におけるDyとTbの組成をDyxTby(原子組成比)、熱処理温度をtとした場合、温度tにおけるDy単独の蒸気圧をPtDy(Pa)、温度tにおけるTb単独の蒸気圧をPtTb(Pa)として、式1:PtTb<Pt<PtDy×(x/(x+y))を満たす圧力Pt(Pa)の雰囲気下で合金を熱処理することで、Dyを気化させることによることを特徴とする方法。
- 熱処理温度tを900℃~1500℃とすることを特徴とする請求項1記載の方法。
- x/(x+y)が0.1以下になるまで合金からDyを気化させることを特徴とする請求項1記載の方法。
- 気化したDyを冷却手段によって固化させることを特徴とする請求項1記載の方法。
- 気化したDyをゲッターに捕捉させることを特徴とする請求項1記載の方法。
- ゲッターの材質がFeであることを特徴とする請求項5記載の方法。
- 合金に含まれるDyとTbが、それぞれR-Fe-B系永久磁石に由来するものであることを特徴とする請求項1記載の方法。
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