EP4268995A1 - Procédé et installation de fabrication d'un matériau de départ pour la fabrication d'aimants à terres rares - Google Patents

Procédé et installation de fabrication d'un matériau de départ pour la fabrication d'aimants à terres rares Download PDF

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Publication number
EP4268995A1
EP4268995A1 EP23190243.8A EP23190243A EP4268995A1 EP 4268995 A1 EP4268995 A1 EP 4268995A1 EP 23190243 A EP23190243 A EP 23190243A EP 4268995 A1 EP4268995 A1 EP 4268995A1
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EP
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Prior art keywords
intermediate product
rare earth
starting material
classifier
powdery intermediate
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EP23190243.8A
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German (de)
English (en)
Inventor
Frank Winter
Hermann Sickel
Dr. Wilhelm FERNENGEL
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Netzsch Trockenmahltechnik GmbH
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Netzsch Trockenmahltechnik GmbH
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B13/00—Grading or sorting solid materials by dry methods, not otherwise provided for; Sorting articles otherwise than by indirectly controlled devices
    • B07B13/003—Separation of articles by differences in their geometrical form or by difference in their physical properties, e.g. elasticity, compressibility, hardness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
    • B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
    • B07B13/00—Grading or sorting solid materials by dry methods, not otherwise provided for; Sorting articles otherwise than by indirectly controlled devices
    • B07B13/04—Grading or sorting solid materials by dry methods, not otherwise provided for; Sorting articles otherwise than by indirectly controlled devices according to size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/052—Metallic powder characterised by the size or surface area of the particles characterised by a mixture of particles of different sizes or by the particle size distribution
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/05—Mixtures of metal powder with non-metallic powder
    • C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/05—Mixtures of metal powder with non-metallic powder
    • C22C1/058—Mixtures of metal powder with non-metallic powder by reaction sintering (i.e. gasless reaction starting from a mixture of solid metal compounds)
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C28/00—Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
    • 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
    • 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
    • H01F1/0536—Alloys characterised by their composition containing rare earth metals sintered
    • 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
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C15/00—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs
    • B02C2015/002—Disintegrating by milling members in the form of rollers or balls co-operating with rings or discs combined with a classifier
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C5/00—Apparatus in which the axial direction of the vortex is reversed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B22F2009/041—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by mechanical alloying, e.g. blending, milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B22F2009/044—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by jet milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C2202/00—Physical properties
    • C22C2202/02—Magnetic
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/025—Making ferrous alloys by powder metallurgy having an intermetallic of the REM-Fe type which is not magnetic

Definitions

  • the present invention relates to a method for producing a starting material for the production of rare earth magnets, a starting material and a system for producing a starting material for the production of rare earth magnets.
  • a permanent magnet (also: permanent magnet) is a piece of a magnetizable material, for example iron, cobalt or nickel, which maintains its static magnetic field without the need for an electrical current flow (unlike electromagnets).
  • a permanent magnet can be created by applying a magnetic field to a ferromagnetic material.
  • rare earth magnets refers to a group of permanent magnets that essentially consist of ferrous metals (iron, cobalt, more rarely nickel) and rare earth metals (especially neodymium, samarium, praseodymium, dysprosium, terbium, gadolinium). They are characterized by the fact that they simultaneously have a high magnetic remanent flux density and a high magnetic coercive field strength and thus a high magnetic energy density.
  • NiFeB neodymium, iron and boron
  • Permanent magnets are made from crystalline powder.
  • the magnetic powder is pressed into a mold in the presence of a strong magnetic field.
  • the crystals align themselves with their preferred magnetization axis in the direction of the magnetic field.
  • the compacts are then sintered. During sintering, the pulverized components of the powder are bonded together or compacted by heating, but none or at least not all of the starting materials are melted.
  • the compacts are heated - often under increased pressure - in such a way that the temperatures remain below the melting temperature of the main components, so that the shape (shape) of the workpiece is retained.
  • the magnetic powder is produced in particular by grinding the corresponding alloys or components, for example in fluid bed jet mills or similar grinding systems.
  • fluid bed jet mills in particular, defined fine grinding takes place, with an exact upper grain limit, but with a not insignificant proportion of fine particles.
  • the comminution energy is provided by gas jets.
  • magnets made from the magnetic powders already known from the prior art have an opposing field stability or coercive field strength that requires improvement due to a high volume percentage of coarse content.
  • the object of the invention is to further optimize the production of the starting mixture for the production of rare earth magnets in order to be able to produce improved rare earth magnets.
  • the invention relates to a method for producing a powdery starting material intended for the production of rare earth magnets.
  • a first step of the method involves comminution of an alloy comprising at least one rare earth metal, with a powdery intermediate product being formed from the alloy comprising at least one rare earth metal.
  • a further step provides for carrying out at least one classification for the powdery intermediate product based on particle size and/or density, with a fraction of the powdery intermediate product formed by means of the at least one classification forming the starting material intended for the production of rare earth magnets.
  • At least one dynamic classifier is provided for the method, which implements at least one dynamic classifier for the powdery intermediate product based on particle size and/or density and thereby separates the fraction from the powdery intermediate product which is the starting material intended for the production of rare earth magnets trains.
  • the powdery intermediate product is fed to at least one static classifier.
  • a static classifier can be removed from the at least one
  • the portion separated from the powdery intermediate product is fed to the at least one dynamic classifier, which implements at least one dynamic classifier, which implements the at least one classification based on particle size and/or density for the portion separated from the powdery intermediate product by means of the at least one static classifier, and in this case the fraction from the portion separates, which forms the starting material intended for the production of rare earth magnets.
  • the at least one dynamic classifier sifts the powdery intermediate product and also disperses it, from which the fraction is separated from the powdery intermediate product, which forms the starting material intended for the production of rare earth magnets.
  • the at least one dynamic classifier separates coarse material from the powdery intermediate product and that, as part of a second classification based on particle size and/or density, the at least one dynamic classifier separates fine material separated from the powdery intermediate product.
  • a portion of the powdery intermediate product separated from the fine and coarse material can provide the fraction that forms the starting material intended for the production of rare earth magnets.
  • Embodiments have proven useful in which the first classification based on particle size and/or density and the second classification based on particle size and/or density are carried out via exactly one dynamic classifier. Furthermore, the alloy comprising at least one rare earth metal can be comminuted, preferably mechanically, in two separate steps, with the powdery intermediate product being formed from the comminutements in separate steps.
  • the at least one dynamic classifier implements the at least one classification based on particle size and/or density for the powdery intermediate product under a protective gas atmosphere.
  • the invention also relates to a starting material intended for the production of rare earth magnets, which is produced by a method according to one of previously described embodiments were produced.
  • a proportion of particles > 8 ⁇ m is ⁇ 2 percent by volume, in particular in a range between 0.1 percent by volume and 1 percent by volume and / or a proportion of particles ⁇ 2 ⁇ m is ⁇ 2 percent by volume and in particular in a range between 0. 05 percent by volume and 2 percent by volume.
  • the invention also relates to a system for producing a powdery starting material intended for the production of rare earth magnets.
  • a system for producing a powdery starting material intended for the production of rare earth magnets can also be provided in the system described below and are therefore not mentioned redundantly.
  • Features described below, which relate to various embodiments of the system according to the invention, can also be provided in the methods already described above.
  • the system for producing a powdery starting material intended for the production of rare earth magnets comprises at least one comminution device, which is aimed at producing a powdery intermediate product by comminuting an alloy comprising at least one rare earth metal.
  • the system further comprises at least one separating device, which can separate a fraction from the powdery intermediate product via at least one classification or sifting based on particle size and/or density, which forms the starting material intended for the production of rare earth magnets.
  • the at least one separating device comprises at least one dynamic classifier, which can separate the fraction from the powdery intermediate product which forms the starting material intended for the production of rare earth magnets via a classification based on particle size and/or density.
  • the at least one separating device comprises at least one static classifier, to which the powdery intermediate product can be fed.
  • the at least one static classifier and the at least one dynamic classifier can be connected to one another in such a way that a portion separated from the supplied intermediate product by means of the at least one static classifier can be fed to the at least one dynamic classifier.
  • the at least one dynamic safe can then, if necessary, separate the fraction from the supplied portion that forms the starting material intended for the production of rare earth magnets.
  • the at least one dynamic classifier is designed to classify and disperse the supplied powdery intermediate product.
  • the at least one comminution device comprises two successive comminution machines, each of which is designed for preferably mechanical comminution of the alloy comprising at least one rare earth metal and interacts with one another to produce the powdery intermediate product from the alloy comprising at least one rare earth metal.
  • Embodiments in which the at least one dynamic filter can implement the classification based on particle size and/or density under a protective gas atmosphere have also proven successful.
  • the starting material which can be produced within the framework of the previously described methods or by means of the previously described system, can essentially comprise particles of a target size range and hardly have any contamination with particles that are smaller than particles of a target size range. These are also referred to below as fine particles. Furthermore, the starting material produced within the framework of the previously described methods or by means of the previously described system can essentially hardly contain any contamination with particles that are larger than the particles of the target size range. These are also referred to below as coarse particles.
  • a starting material which essentially only comprises particles with a size within the target size range in a substantially homogeneous mixture.
  • the starting material which can be produced with the previously described methods or by means of the previously described system, embodiments have proven successful in which the starting material has particles in the target size range between 1 ⁇ m and 10 ⁇ m, in particular in a target size range between 2 ⁇ m and 8 ⁇ m.
  • the starting material has particles in the target size range between 1 ⁇ m and 10 ⁇ m, in particular in a target size range between 2 ⁇ m and 8 ⁇ m.
  • a starting material produced in the context of the preceding processes or by means of the system described above contains ⁇ 2 percent by volume of fine particles, in particular ⁇ 1 percent by volume. Furthermore, it can be provided that the starting material produced in the context of the preceding methods or by means of the system described above comprises ⁇ 2 percent by volume of coarse particles, in particular ⁇ 1 percent by volume.
  • the starting material produced within the framework of the previously described method or by means of the previously described system essentially or predominantly contains particles in the target size range between 2 ⁇ m and 8 ⁇ m, with a proportion of particles whose size is above 8 ⁇ m being ⁇ 2 Percent by volume, in particular in a range between 0.1 percent by volume and 1 percent by volume and where a proportion of particles whose size is below 2 ⁇ m is ⁇ 2 percent by volume, in particular in a range between 0.05 percent by volume and 2 percent by volume.
  • the at least one dynamic classifier already mentioned above and designed as part of the method according to the invention or the system according to the invention can comprise a classifying rotor.
  • a speed of the classifying rotor can, if necessary, be controlled or regulated depending on a particle size distribution desired for the starting material to be produced.
  • a control and/or regulating unit can be provided, which is connected to the at least one dynamic classifier.
  • An algorithm can be stored on the control and/or regulating unit, via which the control and/or regulating unit independently regulates or controls a speed of the classifying rotor designed as a component of the at least one dynamic classifier, taking into account the respective particle size distribution desired for the starting material to be produced .
  • the previously mentioned at least one static classifier which is provided in various embodiments of a method according to the invention or a system according to the invention, can optionally be designed by at least its cyclone classifier.
  • the at least one cyclone classifier can possibly achieve a reduction in the proportion of fine particles.
  • a separated via the at least one static classifier or the at least one cyclone classifier Powdery mixture, which is also referred to below as a powdery intermediate product, usually still contains up to 10 percent by volume of fine particles and / or up to 10 percent by volume of coarse particles even after the fine particles have been separated.
  • the fine particles which are necessarily always present in such a powdery intermediate product, have a detrimental effect on the properties of the rare earth magnets made from them in several respects.
  • the ground powder intermediate product which has possibly already been partially freed of fine particles via the at least one static classifier, is subjected to at least one further classifier process, implemented by at least one dynamic classifier.
  • the powdery intermediate product is first dispersed and then a classification according to particle size and/or density is carried out for the dispersed powdery intermediate product.
  • This dispersion and classification according to particle size and/or density can be carried out in exactly one dynamic classifier. Fine particles and/or coarse particles can then be separated from the powdery intermediate product via the at least one dynamic classifier or exactly one dynamic classifier.
  • the dispersion of the intermediate product and the renewed separation of fine particles and/or coarse particles are carried out within a single device, in particular within a single dynamic classifier. Due to the high chemical reactivity of fine particles that may be present in high concentrations in the powdery intermediate product, the only dynamic classifier can If necessary, carry out dispersion and/or sifting under an inert gas atmosphere. Helium, argon, nitrogen, etc. are used as protective gases.
  • the at least one rare earth metal formed as a component of the alloy can be formed, for example, by iron and/or boron.
  • the alloy comprising at least one rare earth metal can be an NdFeB alloy.
  • a starting material can be produced from this alloy comprising at least one rare earth metal, which essentially only comprises particles in the target size range between 1 ⁇ m to 10 ⁇ m, preferably between 2 ⁇ m to 8 ⁇ m.
  • the starting mixture preferably comprises ⁇ 95 percent by volume, in particular ⁇ 98 percent by volume, of particles in the target size range, which target size range is set from 2 ⁇ m to 8 ⁇ m.
  • the system already described can include a device for the coarse comminution of an alloy comprising at least one rare earth metal.
  • a coarse powder fraction possibly formed from the alloy comprising at least one rare earth metal with the aid of the device for coarse comminution, can optionally be ground into a fine powder fraction in a device for fine comminution, which may be designed as part of the system, the fine powder fraction forming the powdery intermediate product.
  • the device for fine comminution can be designed as a fluid bed jet mill.
  • Figure 1 shows schematically process steps for producing a starting material AM for the production of rare earth magnets.
  • R rare earth metal
  • Fe iron
  • B boron in the desired proportions.
  • an NdFeB alloy is used to produce a so-called neodymium magnet used.
  • an alloy must first be produced from the elements in the desired proportions.
  • this alloy is subjected to coarse grinding. For example, in a mechanical grinding system or through embrittlement with hydrogen. In particular, particles with a size of up to a few mm are generated.
  • the coarse particles gP are chemically stable and can also be easily oriented in magnetic fields, but they have negative effects on the opposing field stability of the magnet because these coarse particles gP remagnetize even in small magnetic opposing fields and thus worsen the opposing field stability (or the coercive field strength) of the entire magnet. For this reason, it is advantageous to further reduce the proportion of coarse particles gP in the starting mixture for the production of sintered permanent magnets.
  • the particles fP of the fine fraction are chemically very reactive due to their fineness and react with the oxygen or even with the nitrogen from the environment even at the lowest oxygen concentrations. These fine particles fP can cause spontaneous powder fires during further processing of the powder.
  • Another disadvantage of the finest particles fP is that these fine powder particles are very difficult to orient in the magnetic fields and pressing devices that are usually available (of the order of magnitude of approximately 10 - 20 kOe) and therefore worsen the remanence of the magnets made from them. For this reason, in a fourth or additional process step, fine particles, in particular particles with a diameter of ⁇ 1-2 ⁇ m, are removed from the fine powder fraction fPF.
  • the mixture is passed through a cyclone that carries the fines through a suitable gas stream and thereby separates it from the mixture.
  • a cyclone that carries the fines through a suitable gas stream and thereby separates it from the mixture.
  • the intermediate product ZP is subjected to at least one further sifting process in order to produce unwanted fine particles fP or coarse particles gP or fine particles fP and coarse particles gP remove and thus further improve the homogeneity of the particles in the target size ZG, in particular in order to obtain a powder mixture as the starting material AM, which essentially only comprises particles with particle sizes in a target range between approximately 2 ⁇ m to 8 ⁇ m, since these particles are magnetically the represent the best powder fraction. All further steps, which in terms of timing follow the step according to number 4, are carried out with the help of a dynamic classifier 10 (cf. Figures 2 and 3 ) or a high-performance classifier.
  • the particles with the target size ZG between 2 ⁇ m to 8 ⁇ m are chemically sufficiently stable so that they do not cause any additional oxidation in the normal manufacturing process. They can also be easily oriented using the usual magnetic fields. They therefore contribute significantly to achieving a high remanence of the magnets produced and are therefore desirable, necessary and useful.
  • the powdery intermediate product ZP is dispersed in order to produce the most homogeneous distribution of the different particles of the intermediate product ZP.
  • molecular and magnetic attractive forces between the particles are overcome and subsequent sifting and separation of fine particles and/or coarse particles following dispersion is possible.
  • a dynamic classifier 10 is also used for this process step (cf. Figures 2 and 3 ) or high-performance classifiers are used.
  • the dispersed powdery intermediate product ZP is sifted again and particles of the fine fraction and/or particles of the coarse fraction are removed. This creates an optimized separation of the finest and coarse particles to achieve the desired target particle size ZG.
  • the fine proportion of particles whose size is less than 1 ⁇ m is reduced to a proportion of less than 1%.
  • the coarse proportion of particles whose size is over 10 ⁇ m can also be reduced to a proportion of less than 1%.
  • This at least one additional classifying process is preferably carried out under a protective gas atmosphere, for example helium, argon, or nitrogen, although this is not intended to represent an exhaustive list of possibilities.
  • a protective gas atmosphere for example helium, argon, or nitrogen, although this is not intended to represent an exhaustive list of possibilities.
  • the protective gas atmosphere particularly prevents spontaneous powder fires due to the fine particles fP.
  • the fifth and sixth process step or the last two process steps ie the dispersion and the separation of fine particles fP and/or the separation of coarse particles gP, can be carried out in a dynamic classifier 10 according to Figures 2 and 3 done together.
  • the powdery intermediate product ZP is fed from above to the classifier device or the dynamic classifier 10 via the product addition 1.
  • the necessary process air VL is supplied through the classifier air inlet 2, which takes the powdery intermediate product ZP supplied via the product addition 1 and leads it through a large number of adjustable guide vane gaps of the static guide vane basket 3, whereby the intermediate product ZP is dispersed.
  • a protective gas is used as the process air VL.
  • the intermediate product ZP dispersed in this way is passed through a classifier wheel 4 whose speed can be continuously adjusted, with the particle sizes being separated either into target and coarse material or into target and fine material.
  • the optimized classifier wheel design ensures that very high fineness levels can be achieved with just one classifier wheel 4, even at high throughputs.
  • the finest particles fP leave the classifier device 10 via the classifier wheel 4, which is installed with a horizontal shaft 8 in the center of the classifier device or the dynamic classifier 10.
  • the coarse particles gP are rejected by the classifier wheel 4 and through the helical design and with a partition 5 Provided machine housing 9 is discharged on the back via the coarse material outlet 6 on the underside of the machine housing 9.
  • the position of the coarse material flap 7 can be used to regulate the discharge of the coarse particles gP in difficult separation tasks, and thus the cleanliness of the coarse particles gP can be influenced.
  • the particles of the target size ZP leave the dynamic classifier 10 together with the coarse material via the coarse material outlet 6.
  • the fine particles fP were separated from the particles of the target size ZP and therefore do not form part of the fraction that leaves the dynamic classifier 10 via the coarse material outlet 6.
  • the desired target particle size ZG is regulated in particular by regulating the gas flow of the process air VL and/or the speed of the classifier wheel 4. A higher gas flow and/or a lower speed lead to a coarser product, while a lower gas flow and/or a higher one speed lead to a finer product.
  • Figure 4 shows the particle size distribution in the intermediate product ZP and in the starting material AM.
  • the diagram plots the particle size in ⁇ m against the proportion of the volume density of the respective mixture in %. It is clearly visible here that through the additional process step of dispersing the intermediate product ZP and sifting with subsequent separation of the finest particles fP ⁇ 1 ⁇ m and/or coarse particles gP ⁇ 10 via a dynamic sifter 10, a more homogeneous particle mixture in the starting material AM can be achieved, in which the proportion of fine particles fP is ⁇ 1% of the volume density and in which the proportion of coarse particles gP is also ⁇ 1% of the volume density. In particular, the hatched portions of fine particles fP and coarse particles gP are removed from the powdery intermediate product ZP.
  • the starting material AM produced in this way is particularly suitable for the production of sintered rare earth magnets due to the particle size between 1 ⁇ m and 10 ⁇ m, preferably between 2 ⁇ m and 8 ⁇ m, since particularly good magnets can be achieved with these particle sizes of the starting material AM.
  • this starting material AM for the production of permanent magnets high (improved) remanence values BR and good (improved) opposing field stability HcJ as well as a significant improvement in the squareness of the demagnetization curve are achieved.
  • Figure 5 shows a scanning electron microscope image of the powdery intermediate product ZP and Figure 6 shows a scanning electron micrograph of the starting material AM, as it is produced in various embodiments of the method according to the invention and can be used for the production of rare earth magnets.
  • the intermediate product ZP represents a highly inhomogeneous mixture of different particle sizes and in particular also contains a high proportion of fine particles fP Figure 6
  • the double-screened starting material AM mainly only contains particles of a target size ZG between 1 ⁇ m and 10 ⁇ m, preferably between 2 ⁇ m and 8 ⁇ m.

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  • Crystallography & Structural Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Powder Metallurgy (AREA)
  • Hard Magnetic Materials (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
EP23190243.8A 2017-07-19 2018-07-10 Procédé et installation de fabrication d'un matériau de départ pour la fabrication d'aimants à terres rares Pending EP4268995A1 (fr)

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DE102017116272.0A DE102017116272A1 (de) 2017-07-19 2017-07-19 Verfahren und anlage zur herstellung eines ausgangsmaterials für die herstellung von seltenerdmagneten
EP18182618.1A EP3431209B1 (fr) 2017-07-19 2018-07-10 Procédé et installation de fabrication d'un matériau de départ pour la fabrication d'aimants à terres rares

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DE102018112406A1 (de) * 2018-05-24 2019-11-28 Netzsch Trockenmahltechnik Gmbh Verfahren und Anlage zur Herstellung eines Ausgangsmaterials für die Herstellung von Seltenerd-Magneten
CN109848030A (zh) * 2019-01-26 2019-06-07 南通理工学院 一种增材制造用原料筛选装置

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JP2000317338A (ja) * 1999-05-11 2000-11-21 Nippon Pneumatic Mfg Co Ltd ジェット粉砕装置及びジェット粉砕方法
US20020129874A1 (en) * 2000-11-08 2002-09-19 Yuji Kaneko Rare earth magnet and method for producing the magnet
WO2007045320A1 (fr) * 2005-10-21 2007-04-26 Vacuumschmelze Gmbh & Co. Kg Poudres pour aimants a base d'elements de terres rares, aimants a base d’elements de terres rares et leurs procedes de fabrication
EP2273513A1 (fr) * 2008-03-31 2011-01-12 Hitachi Metals, Ltd. Aimant fritté de type r-t-b et son procédé de fabrication

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EP0414376A2 (fr) * 1989-07-24 1991-02-27 Shin-Etsu Chemical Co., Ltd. Méthode pour la préparation d'un aimant permanent de terre rare-fer-bore
JP2000317338A (ja) * 1999-05-11 2000-11-21 Nippon Pneumatic Mfg Co Ltd ジェット粉砕装置及びジェット粉砕方法
US20020129874A1 (en) * 2000-11-08 2002-09-19 Yuji Kaneko Rare earth magnet and method for producing the magnet
WO2007045320A1 (fr) * 2005-10-21 2007-04-26 Vacuumschmelze Gmbh & Co. Kg Poudres pour aimants a base d'elements de terres rares, aimants a base d’elements de terres rares et leurs procedes de fabrication
EP2273513A1 (fr) * 2008-03-31 2011-01-12 Hitachi Metals, Ltd. Aimant fritté de type r-t-b et son procédé de fabrication

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EP3431209B1 (fr) 2023-09-20
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US20190027284A1 (en) 2019-01-24
US11660639B2 (en) 2023-05-30
FI3431209T3 (fi) 2023-12-21
LT3431209T (lt) 2024-01-10
RU2706258C1 (ru) 2019-11-15
DK3431209T3 (da) 2024-01-02
EP3431209A1 (fr) 2019-01-23
DE102017116272A1 (de) 2019-01-24
PL3431209T3 (pl) 2024-03-04
US20230271224A1 (en) 2023-08-31
ES2966804T3 (es) 2024-04-24

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