CN115050565A - Preparation method of regenerative sintered neodymium-iron-boron magnet - Google Patents

Preparation method of regenerative sintered neodymium-iron-boron magnet Download PDF

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CN115050565A
CN115050565A CN202210795335.1A CN202210795335A CN115050565A CN 115050565 A CN115050565 A CN 115050565A CN 202210795335 A CN202210795335 A CN 202210795335A CN 115050565 A CN115050565 A CN 115050565A
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powder
magnet
regenerated
rare earth
neodymium
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刘友好
莫军
桂斌
查善顺
衣晓飞
张刚
田朋
王丽英
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Earth Bear Baotou Permanent Magnet Technology Co ltd
Earth Panda Advance Magnetic Material Co Ltd
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Earth Bear Baotou Permanent Magnet Technology Co ltd
Earth Panda Advance Magnetic Material Co Ltd
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    • 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
    • H01F41/02—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 for manufacturing cores, coils, or magnets
    • H01F41/0253—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 for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0573—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes obtained by reduction or by hydrogen decrepitation or embrittlement
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • H01F1/047—Alloys characterised by their composition
    • H01F1/053—Alloys characterised by their composition containing rare earth metals
    • H01F1/055—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5
    • H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
    • H01F1/0571—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes
    • H01F1/0575—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together
    • H01F1/0577—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B in the form of particles, e.g. rapid quenched powders or ribbon flakes pressed, sintered or bonded together sintered
    • 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
    • H01F41/02—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 for manufacturing cores, coils, or magnets
    • H01F41/0253—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 for manufacturing cores, coils, or magnets for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing
    • 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
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies

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  • Crystallography & Structural Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Powder Metallurgy (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Abstract

The invention discloses a preparation method of a regenerative sintered neodymium-iron-boron magnet, which mainly comprises the following steps: pretreating the waste sintered neodymium-iron-boron magnet to obtain a pretreated magnet; mixing the neodymium iron boron alloy ultrafine powder and the pretreated magnet, and then sequentially carrying out hydrogen crushing, airflow milling and cyclone separation to obtain regenerated magnetic powder; mixing the regenerated magnetic powder and the rare earth-rich powder to obtain mixed powder; and sequentially carrying out magnetic field orientation press forming, high-temperature sintering and heat treatment on the mixed powder to obtain the regenerative sintered neodymium-iron-boron magnet. The preparation method can reduce the oxygen content in the regenerated sintered neodymium-iron-boron magnet and improve the performance of the regenerated magnet, so that the regenerated magnet has the characteristics of low oxygen content and high magnetic performance, and a new thought is provided for recycling the waste neodymium-iron-boron magnet.

Description

Preparation method of regenerative sintered neodymium-iron-boron magnet
Technical Field
The invention belongs to the technical field of recycling of waste rare earth permanent magnet materials, and particularly relates to a preparation method of a regenerative sintered neodymium iron boron magnet.
Background
With the rapid development of the fields of new energy automobiles, wind power generation, intelligent manufacturing robots, energy-saving household appliances and the like, the annual output of rare earth permanent magnet materials is continuously increased, a large amount of rare earth resources are consumed, and in the production and processing processes of rare earth products, the reported waste materials are inevitably generated in each process from raw materials to final finished products; meanwhile, a large number of finished products of rare earth permanent magnet motors are scrapped along with the coming of service life, so that the number of waste rare earth magnets available every year is huge. The waste rare earth magnets are fully utilized to prepare the regenerated magnets, so that the secondary rare earth resources can be developed and utilized, the non-renewable primary rare earth resources are saved, and the pollution of the waste magnets can be reduced.
The massive waste sintered neodymium-iron-boron magnet is the largest quantity of waste magnets, the quantity of waste magnets which can be used each year is about more than 5 million tons (the quantity of waste magnets generated in the magnet production process is about 4 million tons, and the quantity of waste magnets disassembled from waste motors is about 1 million tons), and the Nd is well preserved by the waste magnets 2 Fe 14 The magnetic phase B can be prepared into a regenerated magnet (as disclosed in publication Nos. CN102453804A, CN106328364A, CN103093914A, etc.) by washing, crushing and pulverizing the waste magnet, and supplementing rare earth-rich metal or alloy as required. However, the method is limited by the relatively high oxygen content of the waste magnets, and the performance of the regenerated magnets prepared in the method is limited, so that the requirement of high performance of the magnets cannot be met most of the time.
In addition, a certain amount of ultrafine powder is generated in the process of the neodymium iron boron alloy jet milling, which accounts for about 0.5-1.0 wt% of the total production amount, and the neodymium iron boron alloy ultrafine powder has the characteristics of high rare earth content (usually more than 50 wt%), small particle size (average particle size is less than or equal to 1 mu m), large specific surface area, strong reducibility and the like, and can be used as a rare earth-rich alloy to be added into waste magnetic powder for preparing a regenerated magnet. But also limited by the relatively high oxygen content of the waste magnets, the performance of the regenerated magnets prepared in this way is limited, and the requirement of high performance of the magnets cannot be met most of the time.
Disclosure of Invention
In view of the above, the present invention needs to provide a method for preparing a regenerative sintered ndfeb magnet, in which ndfeb alloy ultrafine powder is used as a reducing agent, the ultra-strong oxygen absorption property of the ndfeb alloy ultrafine powder is used to absorb oxygen in waste sintered ndfeb magnetic powder during the preparation of the regenerative magnetic powder, and then based on the characteristic of ultrafine particle size of the ultrafine powder, a cyclone separation process is used to separate ultrafine powder with high oxygen content, so as to reduce the oxygen content in the regenerative sintered ndfeb magnet and improve the performance of the regenerative magnet, so that the regenerative sintered ndfeb magnet has the characteristics of low oxygen content and high magnetic performance.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a preparation method of a regenerative sintered neodymium-iron-boron magnet, which comprises the following steps:
respectively collecting the neodymium iron boron alloy ultrafine powder and the waste sintered neodymium iron boron magnet;
pretreating the waste sintered neodymium iron boron magnet, and removing a coating and/or a plating layer and/or an oxidation rust layer and/or pollutants on the surface of the waste sintered neodymium iron boron magnet to obtain a pretreated magnet;
mixing the neodymium iron boron alloy ultrafine powder with a pretreatment magnet, and then sequentially carrying out hydrogen crushing, airflow milling and cyclone separation to obtain regenerated magnetic powder;
mixing the regenerated magnetic powder and the rare earth-rich powder to obtain mixed powder;
and sequentially carrying out magnetic field orientation press forming, high-temperature sintering and heat treatment on the mixed powder to obtain the regenerative sintered neodymium-iron-boron magnet.
In a further scheme, the neodymium iron boron alloy ultrafine powder is powder with the average particle size of less than or equal to 1 mu m generated in the process of jet milling of the neodymium iron boron alloy;
preferably, the neodymium iron boron alloy ultrafine powder is collected under the conditions of protective gas atmosphere and temperature control;
preferably, the oxygen content in the protective gas atmosphere is less than 100ppm, and the protective gas is selected from one of rare gas and nitrogen;
preferably, the temperature control condition is specifically that the temperature of the powder and the ambient atmosphere in the collection process is controlled to be less than or equal to 30 ℃.
In a further scheme, the main phase component of the waste sintered neodymium-iron-boron magnet is RE x Fe y M y1 B z ；
Wherein RE is at least one of rare earth metals; m is at least one of Co, Cu, Al, Ga, Zr and Nb; x, y1 and z are mass fractions of corresponding elements respectively, x is more than or equal to 29 and less than or equal to 33, y is more than or equal to 0 and less than or equal to 1 and less than or equal to 3, z is more than or equal to 0.95 and less than or equal to 1.05, and y is 100-x-y 1-z.
Further, the pretreatment mode comprises at least one of mechanical polishing, chemical dissolution and ultrasonic water washing.
Further, the mass ratio of the neodymium iron boron alloy ultrafine powder to the pretreated magnet is (5-10): 100.
in a further scheme, the hydrogen crushing process comprises vacuumizing, hydrogen charging, hydrogen absorption, dehydrogenation and cooling, wherein the dehydrogenation temperature is 550-600 ℃, the time is 6-10h, and continuous stirring is carried out while dehydrogenation is carried out.
In a further scheme, the process of the jet mill is carried out under the condition of protective gas, and the pressure of the grinding gas is 0.4-0.6 MPa.
In a further scheme, the particle size distribution of the regenerated magnetic powder meets D 10 ≥1.2μm，3.8μm≤D 50 ≤5.5μm。
Further, the mass ratio of the rare earth-rich powder to the regenerated magnetic powder is (2-5): 100, respectively;
preferably, the rare earth-rich powder is selected from at least one of pure rare earth metal, rare earth hydride, and alloy of rare earth metal and metal N, wherein the rare earth metal is selected from at least one of Ce, Pr, Nd, Dy, Tb, Ho, Gd, and Y, and the metal N is selected from at least one of Fe, Co, Cu, Al, and Ga.
In a further scheme, the magnetic field intensity of the magnetic field orientation compression molding is more than or equal to 1.5T;
the temperature of the high-temperature sintering is 1030-1080 ℃, and the time is 3-5 h;
the heat treatment process specifically comprises the steps of heat treatment at 880-920 ℃ for 3-5h, cooling and heat treatment at 480-520 ℃ for 3-5 h.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the neodymium iron boron alloy ultrafine powder and the waste sintered neodymium iron boron magnet are respectively collected and are mixed to be sequentially subjected to hydrogen crushing and airflow milling to prepare the regenerated magnetic powder, wherein under the high-temperature treatment condition in the dehydrogenation process of hydrogen crushing, the neodymium iron boron alloy ultrafine powder is used as a reducing agent, has strong reducibility and thus super-strong oxygen absorption property, and is used for absorbing oxygen elements in the waste sintered neodymium iron boron magnet. Meanwhile, based on the characteristic that the particle size of the neodymium iron boron alloy ultrafine powder is ultrafine, the ultrafine powder with high oxygen content is separated by utilizing a cyclone separation process, so that the oxygen content of the magnet is reduced.
The invention makes full use of the characteristics of superfine particle size and strong reducibility of the neodymium iron boron alloy superfine powder, so that the prepared regenerative sintered neodymium iron boron magnet has the characteristics of low oxygen content and high magnetic performance.
Detailed Description
The following detailed description of embodiments of the invention is intended to be illustrative, and is not to be construed as limiting the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
The invention provides a preparation method of a regenerative sintered neodymium-iron-boron magnet, which is characterized in that neodymium-iron-boron alloy ultrafine powder and a waste sintered neodymium-iron-boron magnet are mixed, and then the regenerative magnetic powder with low oxygen content is prepared through hydrogen crushing, airflow milling and cyclone separation, so that the prepared regenerative sintered neodymium-iron-boron magnet has the high-performance characteristics of low oxygen content and high coercive force. The preparation method of the regenerative sintered neodymium-iron-boron magnet mainly comprises the following steps:
raw material collection and pretreatment
The raw material collection mainly refers to the collection of neodymium iron boron alloy ultrafine powder and waste sintered neodymium iron boron magnets, wherein the neodymium iron boron alloy ultrafine powder is defined as conventional ultrafine powder in the field, namely powder with the average particle size less than or equal to 1 mu m is generated in the process of jet milling of neodymium iron boron alloy, and the neodymium iron boron alloy ultrafine powder has the characteristics of high rare earth content (more than 50 wt%), small particle size, large specific surface area, strong reducibility and the like. The neodymium iron boron alloy ultrafine powder is mainly collected by the conventional cyclone separation in the field. According to the embodiment of the invention, the neodymium iron boron alloy ultra-fine powder is collected under the conditions of protective gas atmosphere and temperature control, the contact between the neodymium iron boron alloy ultra-fine powder and oxygen is reduced through the protective gas atmosphere, and the chemical activity of the neodymium iron boron alloy ultra-fine powder is reduced through controlling the temperature, so that the oxygen content of the collected neodymium iron boron alloy ultra-fine powder is reduced. The protective gas mentioned here refers to a gas inert to the neodymium iron boron alloy ultrafine powder, and it may be a rare gas (such as helium, argon, etc.), or may be nitrogen, and may be specifically selected according to the actual situation. And the oxygen content in the protective gas atmosphere is < 100 ppm; the temperature control condition is specifically that the temperature of the powder and the ambient atmosphere in the collection process is controlled to be less than or equal to 30 ℃.
Further, the waste sintered ndfeb magnets described herein are not particularly limited, and are mainly waste materials generated during the production and processing of sintered ndfeb products, or waste magnets whose magnetic properties are severely reduced after long-term use. According to the embodiment of the invention, the chemical composition of the main phase component of the waste sintered neodymium-iron-boron magnet is RE x Fe y M y1 B z (ii) a Wherein RE is at least one of rare earth metals (such as Pr, Nd, Dy, etc.); m is at least one of Co, Cu, Al, Ga, Zr and Nb; x, y1 and z are respectively correspondingThe mass fraction of the elements is more than or equal to 29 and less than or equal to 33, y1 is more than or equal to 0 and less than or equal to 3, z is more than or equal to 0.95 and less than or equal to 1.05, and y is 100-x-y 1-z.
Further, the pretreatment described herein is mainly to treat the surface of the waste sintered ndfeb magnet to remove the coating and/or plating and/or oxide rust layer and/or contaminants on the surface thereof, thereby reducing harmful impurities in the regenerated sintered ndfeb magnet and improving the performance of the regenerated sintered ndfeb magnet. It is understood that the pretreatment method is not particularly limited, and may be selected according to the surface condition of the specific waste sintered ndfeb magnet, and the specific pretreatment method that may be used includes, but is not limited to, at least one of mechanical grinding, chemical dissolution, and ultrasonic water washing, which are not specifically described herein. The pretreated magnet is obtained by pretreatment, and the degree of pretreatment can be adjusted according to requirements, particularly based on the condition that the surface of the pretreated magnet has no macroscopic coating and/or plating and/or oxidation rust layer and/or pollutant.
Preparation of regenerated magnetic powder
Specifically, the collected neodymium-iron-boron alloy ultrafine powder and the pretreatment magnet are mixed, and then hydrogen crushing, airflow milling and cyclone separation are sequentially carried out, so that the regenerated magnetic powder is obtained.
In some specific embodiments of the present invention, the mass ratio of the neodymium iron boron alloy ultrafine powder to the pretreated magnet is (5-10): 100.
further, the hydrogen crushing process comprises the steps of vacuumizing, charging hydrogen, absorbing hydrogen, dehydrogenating and cooling, wherein the temperature of the dehydrogenation is 550-600 ℃, the time is 6-10h, the reducibility of the ultrafine powder is further improved by utilizing high-temperature treatment in the dehydrogenation process, the oxygen absorption effect is better exerted, and preferably, the neodymium iron boron alloy ultrafine powder is continuously stirred during dehydrogenation so as to realize the sufficient and uniform oxygen absorption of the crushed regenerated sintered neodymium iron boron magnet by the neodymium iron boron alloy ultrafine powder.
Further, the process of the jet mill is carried out under the condition of protective gas, wherein the pressure of the grinding gas can be freely adjusted according to the used jet mill equipment, and the pressure of the grinding gas used in the embodiment of the invention is 0.4-0.6 MPa. The protective gas used in the process of collecting the NdFeB alloy ultrafine powder is defined as the same, and thus, the detailed description thereof is omitted.
Then, cyclone separation is carried out on the powder after the jet milling, so that ultrafine powder with high oxygen content after oxygen absorption in the powder is separated, and regenerated magnetic powder is obtained, wherein the particle size distribution of the regenerated magnetic powder meets D 10 ≥1.2μm，3.8μm≤D 50 Less than or equal to 5.5 mu m. The cyclone separation parameters are not particularly limited, and can be selected according to actual needs as long as ultrafine powder in the regenerated magnetic powder can be separated.
Supplement rare earth elements
The method comprises the steps of mixing the regenerated magnetic powder and the rare earth-rich powder to supplement the rare earth elements to the regenerated magnetic powder, wherein the specific supplement amount can be adjusted according to practical conditions such as magnet performance requirements, and in some specific embodiments of the invention, the mass ratio of the rare earth-rich powder to the regenerated magnetic powder is (2-5): 100. the rare earth-rich powder as referred to herein refers to a powder containing a rare earth element, and specific examples thereof include at least one of pure rare earth metals, rare earth hydrides, alloys of rare earth metals with a metal N, wherein the rare earth metal is selected from at least one of Ce, Pr, Nd, Dy, Tb, Ho, Gd, Y, and the metal N is selected from at least one of Fe, Co, Cu, Al, Ga.
Preparation of regenerative sintered Nd-Fe-B magnet
And (3) sequentially carrying out magnetic field orientation compression molding, high-temperature sintering and heat treatment on the regenerated magnetic powder supplemented with the rare earth elements to obtain the regenerated sintered neodymium-iron-boron magnet. It will be appreciated that the magnetic field oriented press forming, high temperature sintering and heat treatment processes described herein are all conventional in the art for preparing rare earth permanent magnets, and the specific parameters may be adjusted according to experience and need. In some specific embodiments of the invention, the magnetic field intensity of the magnetic field orientation press forming is more than or equal to 1.5T; the temperature of the high-temperature sintering is 1030-1080 ℃, and the time is 3-5 h; the heat treatment process specifically comprises the steps of heat treatment at 880-920 ℃ for 3-5h, cooling and heat treatment at 480-520 ℃ for 3-5 h.
The method comprises the steps of mixing and crushing neodymium iron boron alloy ultrafine powder and waste sintered neodymium iron boron magnets, and absorbing oxygen elements in the waste sintered neodymium iron boron magnets by utilizing the super-strong oxygen absorbability of the neodymium iron boron alloy ultrafine powder under the high-temperature treatment condition in the dehydrogenation process; and then separating the superfine powder with high oxygen content by utilizing a cyclone separation process based on the characteristic that the particle size of the neodymium iron boron alloy superfine powder is superfine to obtain the regenerated magnetic powder with low oxygen content. The characteristics of the superfine particle size and strong reducibility of the neodymium iron boron alloy superfine powder are fully utilized, and the prepared regenerative sintered neodymium iron boron magnet has the characteristics of low oxygen content and high magnetic performance.
The present invention is illustrated below by way of specific examples, which are intended to be illustrative only and not to limit the scope of the present invention in any way, and reagents and materials used therein are commercially available, unless otherwise specified, and conditions or steps thereof are not specifically described.
Example 1
And (3) collecting superfine powder B10 generated in the process of the NdFeB alloy jet milling with the N52 performance under the protection of argon, wherein the temperature of the powder and the ambient atmosphere in the collecting process is 25 ℃, and the maximum oxygen content in the atmosphere is 90 ppm. The collection part is Pr 6.8 Nd 22.8 Dy 1 Fe 66.64 B 0.96 Co 1 Al 0.3 Cu 0.2 Zr 0.2 Ga 0.1 (wt%) waste magnet M10 generated in the production process of sintered NdFeB magnet; and removing the coating and/or the plating layer and/or the oxidation layer and/or other pollutants on the surface of the magnet M10 by using a mechanical polishing and ultrasonic water washing mode to obtain the pretreated magnet M11, wherein the coating and/or the plating layer and/or the oxidation layer and/or other pollutants on the surface of the pretreated magnet M11 are not remained.
Mixing the superfine powder B10 and the pretreatment magnet M11 according to the mass ratio of 8:100, loading into a hydrogen crushing device, and performing vacuumizing, hydrogen filling, hydrogen absorption, dehydrogenation and cooling treatment to obtain mixed powder P11, wherein the dehydrogenation temperature is 550 ℃, the dehydrogenation time is 8 hours, and the mixture is continuously stirred while dehydrogenation is performed; carrying out nitrogen gas jet milling treatment on the mixed powder P11, wherein the pressure of milling gas is 0.4MPa, and obtaining gas jet milled powder P12; and (3) performing cyclone separation treatment on the airflow milled powder P12 to separate superfine powder in the powder to obtain the regenerated magnetic powder P13, wherein the particle size distribution of the regenerated magnetic powder P13 meets the requirements that D10 is 1.25 mu m, and D50 is 3.92 mu m.
The praseodymium neodymium hydride powder was mixed into the regenerated magnetic powder P13 in a mass ratio of 2:100 (the regenerated magnetic powder was 100), and a mixed powder P14 was obtained.
The mixed powder P14 is subjected to compression molding in a 1.5T magnetic field to form a pressed compact, and the pressed compact is subjected to high-temperature sintering and heat treatment to prepare the regenerative sintered neodymium-iron-boron magnet, wherein the high-temperature sintering process is sintering for 5 hours at 1080 ℃; the heat treatment process comprises heat treatment at 900 deg.C for 3h, cooling, and heat treatment at 500 deg.C for 3 h.
Comparative examples 1 to 1
The waste magnet M10 was collected, and a pretreated magnet M11 was obtained in the same manner as in example 1.
The pretreated magnet M11 was subjected to hydrogen crushing, jet milling, and cyclone separation in the same manner as in example 1, to obtain a regenerated magnetic powder P13 ', which had a particle size distribution of P13' satisfying D10 ═ 1.26 μ M, and D50 ═ 3.95 μ M.
The praseodymium neodymium hydride powder was mixed into the regenerated magnetic powder P13 'in a mass ratio of 2:100 (the regenerated magnetic powder was 100) to obtain a mixed powder P14'.
Compression molding the mixed powder P14' into a pressed blank in a 1.5T magnetic field, and preparing the pressed blank into a regenerative sintered neodymium-iron-boron magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 5 hours at 1080 ℃; the heat treatment process comprises heat treatment at 900 deg.C for 3h, cooling, and heat treatment at 500 deg.C for 3 h.
Comparative examples 1 to 2
This comparative example employed the same embodiment as comparative example 1-1, except that: the praseodymium-neodymium hydride powder was mixed into the regenerated magnetic powder P13' in a ratio of 3:100 (the regenerated magnetic powder was 100) to obtain a mixed powder P14 ".
Comparative examples 1 to 3
Collecting the same superfine powder B10 as in example 1 by the same collection process as in example 1;
the same waste magnet M10 as in example 1 was collected, and a pretreated magnet M11 was obtained in the same manner as in example 1.
The pretreated magnet M11 was subjected to hydrogen pulverization, jet milling, and cyclone separation in this order in the same manner as in example 1 to obtain a regenerated magnetic powder P13 ', and the particle size distribution of the regenerated magnetic powder P13' satisfied D10 ═ 1.26 μ M, and D50 ═ 3.95 μ M.
Mixing the regenerated magnetic powder P13' with the ultrafine powder B10 according to the mass ratio of 8:100 (the mass ratio of the regenerated magnetic powder is 100) to obtain mixed magnetic powder; then, according to the following 2:100 (the mixed magnetic powder is 100) to obtain mixed powder P14'.
Carrying out compression molding on the mixed powder P14' in a 1.5T magnetic field to form a pressed blank, and preparing the pressed blank into a regenerative sintered neodymium-iron-boron magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 5 hours at 1080 ℃; the heat treatment process comprises heat treatment at 900 deg.C for 3h, cooling, and heat treatment at 500 deg.C for 3 h.
At room temperature, a permanent magnet material measuring system is used for testing the magnetic performance of the regenerative sintered NdFeB magnet in the example 1 and the comparative examples 1-1, 1-2 and 1-3 according to the method specified in GB/T3217-2013; the oxygen content of the regenerated sintered nd-fe-b magnets of example 1 and comparative examples 1-1, 1-2, 1-3 was measured using an oxygen content tester. The results are shown in Table 1.
TABLE 1 magnetic Properties and oxygen content test results of the regenerated sintered NdFeB magnet
Figure BDA0003735579780000071
As can be seen from the test results in table 1, the regenerated sintered nd-fe-b magnet prepared in example 1 has the characteristics of high magnetic properties and low oxygen content. Among them, it can be seen that, although comparative examples 1 to 3 have a coercive force higher than that of example 1, the remanence values thereof are significantly lower than that of example 1, and the oxygen content is significantly higher than that of example 1, so that, in combination, the magnetic properties of comparative examples 1 to 3 are inferior to that of example 1.
Example 2
And collecting superfine powder B20 generated in the 42H neodymium iron boron alloy jet milling process under the protection of nitrogen, wherein the temperature of the powder and the ambient atmosphere in the collecting process is 20 ℃, and the maximum oxygen content in the atmosphere is 95 ppm. The collection part is Pr 5.5 Nd 22 Ho 4 Fe 65.94 B 0.96 Co 1 Al 0.4 Cu 0.2 (wt%) waste magnet M20 generated in the production process of sintered NdFeB magnet; and removing the coating and/or the plating layer and/or the oxidation layer and/or other pollutants on the surface of the magnet M20 by using a dilute hydrochloric acid dissolution and ultrasonic water washing mode to obtain the pretreated magnet M21, wherein the surface of the pretreated magnet M21 has no macroscopic coating and/or plating layer and/or oxidation layer and/or other pollutants.
Mixing the superfine powder B20 and the pretreatment magnet M21 according to the mass ratio of 5:100, loading into a hydrogen crushing device, and performing vacuumizing, hydrogen filling, hydrogen absorption, dehydrogenation and cooling treatment to obtain mixed powder P21, wherein the dehydrogenation temperature is 560 ℃, the dehydrogenation time is 10 hours, and the mixture is continuously stirred while dehydrogenation is performed; carrying out nitrogen gas jet milling treatment on the mixed powder P21, wherein the pressure of the milling gas is 0.45MPa, and obtaining gas jet milled powder P22; and (3) performing cyclone separation treatment on the airflow milled powder P22 to separate ultrafine powder from the powder to obtain the regenerated magnetic powder P23, wherein the particle size distribution of the regenerated magnetic powder P23 meets the requirements that D10 is 1.28 mu m, and D50 is 4.03 mu m.
Nd was mixed into the regenerated magnetic powder P23 in a mass ratio of 3:100 (100 for the regenerated magnetic powder) 80 Fe 20 (wt%) alloy powder to obtain mixed powder P24.
Carrying out compression molding on the mixed powder P24 in a 1.7T magnetic field to form a pressed blank, and preparing the pressed blank into a regenerative sintered neodymium-iron-boron magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 4 hours at 1070 ℃; the heat treatment process comprises heat treatment at 880 deg.C for 4 hr, cooling, and heat treatment at 480 deg.C for 3 hr.
Comparative example 2-1
The waste magnet M20 was collected, and a pretreated magnet M21 was obtained in the same manner as in example 2.
The pretreated magnet M21 was subjected to hydrogen pulverization, jet milling, and cyclone separation in this order in the same manner as in example 2 to obtain a regenerated magnetic powder P23 ', the particle size distribution of which regenerated magnetic powder P23' satisfied D10 ═ 1.29 μ M, and D50 ═ 4.05 μ M.
Nd was mixed into the regenerated magnetic powder P23' in a mass ratio of 3:100 (100 for the regenerated magnetic powder) 80 Fe 20 (wt%) alloy powder to obtain mixed powder P24'.
The mixed powder P24' is molded into a pressed compact in a 1.7T magnetic field, and the pressed compact is prepared into a regenerative sintered NdFeB magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 4 hours at 1070 ℃; the heat treatment process comprises heat treatment at 880 deg.C for 4 hr, cooling, and heat treatment at 480 deg.C for 3 hr.
Comparative examples 2 to 2
This comparative example employed the same embodiment as comparative example 2-1, except that: nd was mixed into the regenerated magnetic powder P23' in a ratio of 4:100 (the regenerated magnetic powder is 100) 80 Fe 20 (wt%) alloy powder to obtain mixed powder P24 ".
Comparative examples 2 to 3
Collecting the same superfine powder B20 as in example 2 by the same collection process as in example 2;
the same waste magnet M20 as in example 2 was collected, and a pretreated magnet M21 was obtained in the same manner as in example 2.
The pretreated magnet M21 was subjected to hydrogen pulverization, air flow milling, and cyclone separation in the same manner as in example 2, to obtain a regenerated magnetic powder P23 ', which had a particle size distribution of P23' satisfying D10 ═ 1.29 μ M, and D50 ═ 4.05 μ M.
Mixing the regenerated magnetic powder P23' with super-high magnetic powder at a mass ratio of 5:100 (100 for regenerated magnetic powder)Fine powder B20 to obtain mixed magnetic powder; then, according to the following 3: nd is mixed into the mixed magnetic powder according to the mass ratio of 100 (the mixed magnetic powder is 100) 80 Fe 20 (wt%) alloy powder to obtain mixed powder P24 "'.
Carrying out compression molding on the mixed powder P24' in a 1.7T magnetic field to form a pressed blank, and preparing the pressed blank into a regenerative sintered neodymium-iron-boron magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 4 hours at 1070 ℃; the heat treatment process comprises heat treatment at 880 deg.C for 4 hr, cooling, and heat treatment at 480 deg.C for 3 hr.
The magnetic properties and oxygen contents of the regenerated sintered nd-fe-b magnets prepared in example 2 and comparative examples 2-1, 2-2, 2-3 were measured in the same test manner as in example 1, and the results are shown in table 2.
TABLE 2 magnetic Properties and oxygen content test results of the regenerated sintered NdFeB magnets
Figure BDA0003735579780000091
As can be seen from table 2, the regenerated magnet obtained in example 2 has high magnetic properties and low oxygen content. Among them, it can be seen that, although comparative examples 2 to 3 have a coercive force higher than that of example 2, the remanence values thereof are significantly lower than that of example 2, and the oxygen content is significantly higher than that of example 2, so that comparative examples 2 to 3, taken together, have magnetic properties inferior to that of example 2.
Example 3
And collecting superfine powder B30 generated in the 45M performance neodymium iron boron alloy jet milling process under the protection of nitrogen, wherein the temperature of the powder and the ambient atmosphere in the collecting process is 28 ℃, and the maximum oxygen content in the atmosphere is 90 ppm. The collecting component is Nd 28 Dy 1.5 Ho 1 Fe 68.3 B 1 Al 0.3 Ga 0.2 Nb 0.2 (wt%) waste magnet M30 generated in the production process of sintered NdFeB magnet; removing the coating and/or plating and/or oxidation layer and/or other pollutants on the surface of the magnet M30 by sanding and ultrasonic water washing to obtain a pretreated magnet M31, wherein the surface of the pretreated magnet M31 has no naked eyeVisible coating and/or plating and/or oxide layer and/or other contaminant residue.
Mixing the superfine powder B30 and the pretreatment magnet M31 according to the mass ratio of 7:100, loading the mixture into hydrogen crushing equipment, and performing vacuumizing, hydrogen charging, hydrogen absorption, dehydrogenation and cooling treatment to obtain mixed powder P31, wherein the dehydrogenation temperature is 580 ℃, the dehydrogenation time is 7 hours, and the mixture is continuously stirred while dehydrogenation is performed; carrying out nitrogen gas jet milling treatment on the mixed powder P31, wherein the pressure of the milling gas is 0.5MPa, and obtaining gas jet milled powder P32; and (3) performing cyclone separation treatment on the airflow milled powder P32 to separate superfine powder in the powder to obtain the regenerated magnetic powder P33, wherein the particle size distribution of the regenerated magnetic powder P33 meets the requirements that D10 is 1.22 mu m and D50 is 3.87 mu m.
Metal neodymium powder was mixed into the regenerated magnetic powder P33 in a mass ratio of 4:100 (the regenerated magnetic powder is 100) to obtain mixed powder P34.
The mixed powder P34 is subjected to compression molding in a 1.8T magnetic field to form a pressed blank, and the pressed blank is subjected to high-temperature sintering and heat treatment to prepare the regenerative sintered neodymium-iron-boron magnet, wherein the high-temperature sintering process is sintering for 3 hours at 1060 ℃; the heat treatment process comprises heat treatment at 900 deg.C for 5h, cooling, and heat treatment at 520 deg.C for 5 h.
Comparative example 3-1
The waste magnet M30 was collected, and a pretreated magnet M31 was obtained in the same manner as in example 3.
The pretreated magnet M31 was subjected to hydrogen crushing, air flow milling, and cyclone separation in this order in the same manner as in example 3 to obtain a regenerated magnetic powder P33 ', which had a particle size distribution of P33' satisfying D10 ═ 1.22 μ M, and D50 ═ 3.88 μ M.
Metallic neodymium powder was mixed into the regenerated magnetic powder P33 'in a mass ratio of 4:100 (the regenerated magnetic powder is 100) to obtain mixed powder P34'.
The mixed powder P34' is molded into a pressed blank by compression in a 1.8T magnetic field, and the pressed blank is prepared into a regenerative sintered NdFeB magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 3 hours at 1060 ℃; the heat treatment process comprises heat treatment at 900 deg.C for 5h, cooling, and heat treatment at 520 deg.C for 5 h.
Comparative examples 3 to 2
This comparative example employed the same embodiment as comparative example 3-1, except that: metal neodymium powder was mixed into the regenerated magnetic powder P33 'in a ratio of 5:100 (the regenerated magnetic powder is 100) to obtain mixed powder P34'.
The magnetic properties and oxygen contents of the regenerated sintered nd-fe-b magnets prepared in example 3 and comparative examples 3-1 and 3-2 were measured in the same test manner as in example 1, and the results are shown in table 3.
TABLE 3 magnetic Properties and oxygen content test results of the regenerated sintered NdFeB magnets
Figure BDA0003735579780000101
As can be seen from table 3, the regenerated magnet obtained in example 3 is characterized by high magnetic properties and low oxygen content.
Example 4
And collecting the superfine powder B40 generated in the process of the neodymium-iron-boron alloy jet milling with the 40SH performance under the protection of nitrogen, wherein the temperature of the powder and the ambient atmosphere in the collecting process is 23 ℃, and the maximum oxygen content in the atmosphere is 95 ppm. The collecting component is Nd 28 Gd 4.5 Fe 65. 8 B 1 Al 0.3 Ga 0.2 Zr 0.2 (wt%) waste magnet M40 generated in the production process of sintered NdFeB magnet; and removing the coating and/or the plating layer and/or the oxidation layer and/or other pollutants on the surface of the magnet M40 by using a mechanical shot blasting and ultrasonic water washing mode to obtain the pretreated magnet M41, wherein the surface of the pretreated magnet M41 has no macroscopic coating and/or plating layer and/or oxidation layer and/or other pollutants.
Mixing the ultrafine powder B40 and a pretreatment magnet M41 according to the mass ratio of 10:100, loading the mixture into hydrogen crushing equipment, and performing vacuum pumping, hydrogen charging, hydrogen absorption, dehydrogenation and cooling treatment to obtain mixed powder P41, wherein the dehydrogenation temperature is 600 ℃, the dehydrogenation time is 6 hours, and the mixture is continuously stirred while dehydrogenation is performed; carrying out nitrogen gas jet milling treatment on the mixed powder P41, wherein the pressure of the milling gas is 0.6MPa, and obtaining gas jet milled powder P42; and (3) performing cyclone separation treatment on the airflow milled powder P42 to separate superfine powder in the powder to obtain the regenerated magnetic powder P43, wherein the particle size distribution of the regenerated magnetic powder P43 meets the requirements that D10 is 1.3 mu m, and D50 is 4.15 mu m.
Mixing Pr into the regenerated magnetic powder P43 according to the mass ratio of 5:100 (the regenerated magnetic powder is 100) 15 Nd 35 Dy 10 Fe 30 Co 10 (wt%) alloy powder to obtain mixed powder P44.
Carrying out compression molding on the mixed powder P44 in a 1.9T magnetic field to form a pressed blank, and preparing the pressed blank into a regenerative sintered neodymium-iron-boron magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 4 hours at 1030 ℃; the heat treatment process comprises heat treatment at 920 ℃ for 3h, cooling, and heat treatment at 500 ℃ for 4 h.
Comparative example 4-1
The waste magnet M40 was collected, and a pretreated magnet M41 was obtained in the same manner as in example 4.
The pretreated magnet M41 was subjected to hydrogen crushing, air flow milling, and cyclone separation in this order in the same manner as in example 4 to obtain a regenerated magnetic powder P43 ', which had a particle size distribution of P43' satisfying D10 ═ 1.29 μ M, and D50 ═ 4.13 μ M.
Mixing Pr into the regenerated magnetic powder P43' according to the mass ratio of 4:100 (the regenerated magnetic powder is 100) 15 Nd 35 Dy 10 Fe 30 Co 10 (wt%) alloy powder to obtain mixed powder P44'.
Carrying out compression molding on the mixed powder P44' in a 1.9T magnetic field to form a pressed blank, and preparing the pressed blank into a regenerative sintered neodymium-iron-boron magnet through high-temperature sintering and heat treatment, wherein the high-temperature sintering process is sintering for 4 hours at 1030 ℃; the heat treatment process comprises heat treatment at 920 ℃ for 3h, cooling, and heat treatment at 500 ℃ for 4 h.
Comparative examples 4 to 2
This comparative example employed the same embodiment as comparative example 4-1, except that: mixing Pr into the regenerated magnetic powder P43' according to the proportion of 6:100 (the regenerated magnetic powder is 100) 15 Nd 35 Dy 10 Fe 30 Co 10 (wt%) alloy powder to obtain mixed powder P44 ".
The magnetic properties and oxygen contents of the regenerated sintered nd-fe-b magnets prepared in example 4 and comparative examples 4-1 and 4-2 were measured in the same test manner as in example 1, and the results are shown in table 4.
TABLE 4 magnetic Properties and oxygen content test results of the regenerated sintered NdFeB magnets
Figure BDA0003735579780000121
As can be seen from Table 4, the regenerated magnet obtained in example 4 is characterized by high magnetic properties and low oxygen content.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is specific and detailed, but not to be understood as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (10)

1. The preparation method of the regenerative sintered neodymium-iron-boron magnet is characterized by comprising the following steps:
respectively collecting the neodymium iron boron alloy ultrafine powder and the waste sintered neodymium iron boron magnet;
pretreating the waste sintered neodymium iron boron magnet, and removing a coating and/or a plating layer and/or an oxidation rust layer and/or pollutants on the surface of the waste sintered neodymium iron boron magnet to obtain a pretreated magnet;
mixing the neodymium iron boron alloy ultrafine powder with a pretreatment magnet, and then sequentially carrying out hydrogen crushing, airflow milling and cyclone separation to obtain regenerated magnetic powder;
mixing the regenerated magnetic powder and the rare earth-rich powder to obtain mixed powder;
and sequentially carrying out magnetic field orientation press forming, high-temperature sintering and heat treatment on the mixed powder to obtain the regenerative sintered neodymium-iron-boron magnet.
2. The preparation method of claim 1, wherein the ndfeb alloy ultrafine powder is a powder having an average particle size of 1 μm or less generated during the jet milling of the ndfeb alloy;
preferably, the neodymium iron boron alloy ultrafine powder is collected under the conditions of protective gas atmosphere and temperature control;
preferably, the oxygen content in the protective gas atmosphere is less than 100ppm, and the protective gas is selected from one of rare gas and nitrogen;
preferably, the temperature control condition is to control the temperature of the powder and the ambient atmosphere in the collection process to be less than or equal to 30 ℃.
3. The preparation method according to claim 1, wherein the main phase component of the waste sintered neodymium-iron-boron magnet is RE x Fe y M y1 B z ；
Wherein RE is at least one of rare earth metals; m is at least one of Co, Cu, Al, Ga, Zr and Nb; x, y1 and z are mass fractions of corresponding elements respectively, x is more than or equal to 29 and less than or equal to 33, y is more than or equal to 0 and less than or equal to 1 and less than or equal to 3, z is more than or equal to 0.95 and less than or equal to 1.05, and y is 100-x-y 1-z.
4. The method of claim 1, wherein the pre-treatment comprises at least one of mechanical polishing, chemical dissolution, and ultrasonic water washing.
5. The preparation method of claim 1, wherein the mass ratio of the neodymium-iron-boron alloy ultrafine powder to the pre-processed magnet is (5-10): 100.
6. the preparation method as claimed in claim 1, wherein the hydrogen crushing process comprises vacuumizing, charging, absorbing hydrogen, dehydrogenating and cooling, wherein the temperature of the dehydrogenation is 550-600 ℃, the time is 6-10h, and the dehydrogenation is continuously stirred.
7. The method of claim 1, wherein the jet mill is carried out under a protective gas atmosphere at a pressure of 0.4 to 0.6 MPa.
8. The production method according to claim 1, wherein the particle size distribution of the regenerated magnetic powder satisfies D 10 ≥1.2μm，3.8μm≤D 50 ≤5.5μm。
9. The production method according to claim 1, wherein the mass ratio of the rare earth-rich powder to the regenerated magnetic powder is (2-5): 100, respectively;
preferably, the rare earth-rich powder is selected from at least one of pure rare earth metal, rare earth hydride, and alloy of rare earth metal and metal N, wherein the rare earth metal is selected from at least one of Ce, Pr, Nd, Dy, Tb, Ho, Gd, and Y, and the metal N is selected from at least one of Fe, Co, Cu, Al, and Ga.
10. The preparation method according to claim 1, wherein the magnetic field strength of the magnetic field orientation compression molding is more than or equal to 1.5T;
the temperature of the high-temperature sintering is 1030-1080 ℃, and the time is 3-5 h;
the heat treatment process specifically comprises the steps of heat treatment at 880-920 ℃ for 3-5h, cooling and heat treatment at 480-520 ℃ for 3-5 h.
CN202210795335.1A 2022-07-07 2022-07-07 Preparation method of regenerative sintered neodymium-iron-boron magnet Pending CN115050565A (en)

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