EP0272250B1 - Process for the production of neodym alloys - Google Patents

Process for the production of neodym alloys Download PDF

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Publication number
EP0272250B1
EP0272250B1 EP88100014A EP88100014A EP0272250B1 EP 0272250 B1 EP0272250 B1 EP 0272250B1 EP 88100014 A EP88100014 A EP 88100014A EP 88100014 A EP88100014 A EP 88100014A EP 0272250 B1 EP0272250 B1 EP 0272250B1
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German (de)
French (fr)
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EP0272250A1 (en
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Françoise Seon
Bernard Boudot
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Rhodia Chimie SAS
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Rhone Poulenc Chimie SA
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Priority claimed from FR8311139A external-priority patent/FR2548687B1/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/04—Dry methods smelting of sulfides or formation of mattes by aluminium, other metals or silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B59/00—Obtaining rare earth metals
    • 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

Definitions

  • the present invention relates to a method for manufacturing neodymium alloys.
  • ceric rare earth metals a designation which includes lanthanum, cerium, praseodymium and neodymium, the latter is the only metal that cannot be manufactured industrially by electrolysis of these salts. Indeed, it is mentioned in the article by T. KURITA (Denki Kagaku, 1967, 35 (7) p.496-501) that yields of 6 to 20% of pure neodymium are obtained by electrolysis in a molten bath - neodymium chloride, potassium chloride -.
  • neodymium alloys more particularly neodymium and magnesium alloys, which consists in using neodymium chloride, an alkali metal and magnesium, all the reagents being introduced and kept in the molten state throughout the duration of the reaction.
  • the objective of the present invention is to provide an industrial process for manufacturing neodymium and iron alloys, with a high neodymium content, which is easy to carry out.
  • neodymium and iron alloys of the type consisting in reducing a neodymium fluoride using calcium, in the presence of iron, and characterized in that the quantity of iron is defined so that the neodymium-iron alloy has an iron content of 5 at 30%, and in that calcium chloride is added to the reaction medium.
  • neodymium fluoride is used.
  • Neodymium fluoride is available in an anhydrous state because it is a low hygroscopic product.
  • the drying time can vary between 2 and 24 hours.
  • drying conditions are not critical and are given on a preferential basis.
  • the particle size of neodymium fluoride can vary. It is commercially available in the form of a powder, the particle size of which varies from 40 to 150 ⁇ m. The particle size influencing the reduction speed, it is recommended that the powder is fine which can lead to a grinding operation so that the average diameter of the neodymium fluoride particles is less than 100 ⁇ m. There is no lower diameter limit.
  • the reducing metal used in the process of the invention is calcium.
  • the reducing metal is used in the form in which it is sold, whether it is in the solid state or in the form of pellets or balls.
  • calcium chloride is added to the reaction medium in order to lower the melting point and the density of the slag formed in the reaction so that the neodymium-iron formed alloy separates more easily.
  • the method of the invention consists in mixing a neodymium fluoride, calcium. iron and calcium chloride in the proportions given below.
  • the amount of calcium can vary within wide limits. However, it is advantageous to use an amount sufficient to reduce the neodymium fluoride but it should not be too large if one does not wish to find it, in an important way, in the final alloy.
  • the amount of reducing metal is at least equal to the stoichiometric amount or even in slight excess, up to 20% of the stoichiometric amount.
  • the amount of iron is adjusted according to the desired composition of the alloy. It is such that a fusible alloy with neodymium is obtained at the reaction temperature. It is calculated so that iron represents from 5 to 30% of the weight of the alloy obtained.
  • the amount of calcium chloride added is adjusted in order to obtain a slag containing from 30 to 70% by weight of calcium chloride and preferably 60 to 70%.
  • the different neodymium and calcium halides and iron constitute "a filler" having the desired weight composition.
  • the constituents of this charge can be reacted in any order: by simultaneous mixing of all the constituents or by making premixes, on the one hand, the neodymium and calcium halides and on the other hand calcium and iron.
  • the reaction is carried out at a temperature between 800 ° C and 1100 ° C.
  • the upper limit of temperature is not critical and can reach a value as high as 1400 ° C.
  • a temperature between 900 ° C and 1100 ° C is chosen.
  • the reaction is carried out at atmospheric pressure but in an inert gas atmosphere.
  • the air is excluded by lowering from pressure to a non-critical value, for example between 1 mm and 100 mm of mercury, then a scan of inert gases is carried out: rare gases, in particular argon. It is desirable to subject the rare gas to a dehydration and deoxygenation treatment carried out according to the usual techniques, for example by passage through a molecular sieve.
  • the inert atmosphere is maintained throughout the reduction.
  • the duration of the reaction depends on the capacity of the apparatus and its ability to rapidly rise in temperature. Generally once the desired temperature has been reached, it is maintained for a variable period of approximately 30 minutes to 3 hours.
  • a metallic phase consisting of the neodymium-iron alloy on which floats a slag consisting of CaF2-CaCl2 having a density lower than that of the alloy.
  • the alloy can be immediately separated from the slag by hot casting or allowed to cool under an inert gas atmosphere at room temperature (15 to 25 ° C) so that the alloy solidifies and can then be removed from the mold.
  • the yield of neodymium in the alloy expressed relative to the neodymium contained in the halide varies from 80 to 96%.
  • the method of the invention as described, can be implemented in an apparatus of conventional type, used in metallurgy.
  • the reduction is carried out in a crucible placed in a reactor made of a material resistant to hydrofluoric and hydrochloric vapors. It can be chosen from refractory steel, for example, steel containing 25% chromium and 20% nickel, but preferably inconel which is an alloy containing nickel, chromium (20%), iron (5%), molybdenum (8-10%).
  • Said reactor is equipped with a temperature control device (eg thermocouple), an inlet and outlet of inert gases. It is provided in its upper part with a double envelope in which circulates a coolant.
  • This reactor is placed in an induction furnace or in an furnace heated by electrical resistances.
  • a crucible in which the temperature control device is immersed is placed at the bottom of the reactor. It must be made of a material resistant to neodymium fluoride or have a coating resistant to them.
  • a tantalum crucible is used.
  • the molten alloy can be cast in molds, for example, cast iron.
  • the alloys obtained according to the present invention are very rich in neodymium since they can contain up to 95%.
  • They can be used as master alloys in particular in the manufacture of permanent magnets.
  • a premix is then made containing 382.2 g of calcium chloride in the dry state and 281.4 g of neodymium fluoride having an average particle diameter of 60 ⁇ m.
  • the previously defined load is then ready for use.
  • the calciothermic reduction reaction of neodymium fluoride is carried out in a tantalum crucible of about 1 liter placed at the bottom of an inconel reactor which is equipped with an inlet and an argon outlet and a thermocouple introduced into a thermometric sheath which is immersed in the reaction medium contained in the crucible: the upper part of the reactor is provided with a double jacket in which cold water circulates (about 10 ° C).
  • a temperature rise is carried out at the same time until the temperature fixed at 1100 ° C. is obtained; this temperature being kept constant for another 30 minutes.
  • neodymium-iron alloy 562 g are collected and 188 g of a neodymium-iron alloy are recovered by hot casting in a cast iron ingot mold.
  • the neodymium yield in the alloy expressed relative to the neodymium contained in the neodymium fluoride is 81%.

Description

La présente invention a trait à un procédé de fabrication d'alliages de néodyme.The present invention relates to a method for manufacturing neodymium alloys.

Parmi les métaux des terres rares cériques, appellation qui regroupe le lanthane, le cérium, le praséodyme et le néodyme, ce dernier est le seul métal qui ne puisse être fabriqué industriellement par électrolyse de ces sels. En effet, il est mentionné dans l'article de T. KURITA (Denki Kagaku, 1967, 35 (7) p.496-501) que l'on obtient des rendements de 6 à 20 % de néodyme pur par électrolyse en bain fondu - chlorure de néodyme, chlorure de potassium -.Among the ceric rare earth metals, a designation which includes lanthanum, cerium, praseodymium and neodymium, the latter is the only metal that cannot be manufactured industrially by electrolysis of these salts. Indeed, it is mentioned in the article by T. KURITA (Denki Kagaku, 1967, 35 (7) p.496-501) that yields of 6 to 20% of pure neodymium are obtained by electrolysis in a molten bath - neodymium chloride, potassium chloride -.

Par conséquent, l'obtention d'alliages de néodyme à partir de néodyme métallique n'apparait pas comme une voie valable industriellement.Consequently, obtaining neodymium alloys from metallic neodymium does not appear to be an industrially valid route.

Un procédé de ce type a été utilisé pour l'élaboration du diagramme fer-néodyme [cf. "Iron-Binary Phase Diagrams" 0. Kubaschewski (1982) p. 101 et 102].A process of this type was used for the development of the iron-neodymium diagram [cf. "Iron-Binary Phase Diagrams" 0. Kubaschewski (1982) p. 101 and 102].

Il est également connu, selon AT-328 884, un procédé de fabrication d'alliages de néodyme, plus particulièrement d'alliages de néodyme et de magnésium, qui consiste à mettre en oeuvre un chlorure de néodyme, un métal alcalin et du magnésium, tous les réactifs étant introduits et maintenus à l'état fondu pendant toute la durée de la réaction.It is also known, according to AT-328 884, a process for manufacturing neodymium alloys, more particularly neodymium and magnesium alloys, which consists in using neodymium chloride, an alkali metal and magnesium, all the reagents being introduced and kept in the molten state throughout the duration of the reaction.

Il est également connu du document "CHIMIE ET INDUSTRIE, Vol. 77, no 2, fev. 1957, P. 277-288" de préparer des terres rares, ou des mélanges terres rares - métal, par réaction de fluorures de terres rares, en présence éventuellement dudit métal, avec du calcium.It is also known from "CHEMISTRY AND INDUSTRY, Vol 77, No. 2, February 1957, p 277-288.." To prepare rare earth or mixtures rare earth - metal by reacting rare earth fluorides , optionally in the presence of said metal, with calcium.

L'objectif de la présente invention est de proposer un procédé industriel de fabrication d'alliages de néodyme et de fer, à titre élevé en néodyme, et qui soit de mise en oeuvre aisée.The objective of the present invention is to provide an industrial process for manufacturing neodymium and iron alloys, with a high neodymium content, which is easy to carry out.

Selon la présente invention, il est maintenant proposé un procédé de fabrication d'alliages de néodyme et de fer, du type consistant à réduire un fluorure de néodyme à l'aide de calcium, en présence de fer, et caractérisé en ce que la quantité de fer est définie de telle sorte que l'alliage néodyme-fer ait une teneur en fer de 5 à 30 %, et en ce que l'on ajoute au milieu réactionnel du chlorure de calciun.According to the present invention, there is now proposed a method for manufacturing neodymium and iron alloys, of the type consisting in reducing a neodymium fluoride using calcium, in the presence of iron, and characterized in that the quantity of iron is defined so that the neodymium-iron alloy has an iron content of 5 at 30%, and in that calcium chloride is added to the reaction medium.

Conformément à l'invention, on fait appel au fluorure de néodyme.In accordance with the invention, neodymium fluoride is used.

Il est souhaitable qu'il soit d'une grande pureté c'est-à-dire exempt d'oxyde résiduaire et d'oxyhalogénure et qu'il soit sec : sa teneur en eau doit être inférieure à 5 % et de préférence inférieure à 2 %.It is desirable that it be of high purity, that is to say free of residual oxide and of oxyhalide and that it be dry: its water content must be less than 5% and preferably less than 2%.

Le fluorure de néodyme est disponible à l'état anhydre car c'est un produit peu hygroscopique.Neodymium fluoride is available in an anhydrous state because it is a low hygroscopic product.

Il est également possible, si nécessaire, de soumettre le fluorure à une étape de séchage à une température comprise entre 100°C et 500°C mais de préférence entre 200°C et 250°C. Cette opération peut être faite à l'air ou sous pression réduite comprise par exemple entre 1 mm de mercure (= 133,322 Pa) et 100 mm de mercure (= 13 332,2 Pa).It is also possible, if necessary, to subject the fluoride to a drying step at a temperature between 100 ° C and 500 ° C but preferably between 200 ° C and 250 ° C. This operation can be done in air or under reduced pressure, for example between 1 mm of mercury (= 133,322 Pa) and 100 mm of mercury (= 13,332.2 Pa).

La durée de séchage peut varier entre 2 et 24 heures.The drying time can vary between 2 and 24 hours.

Les conditions énoncées ci-dessus de séchage ne présentent aucun caractère critique et sont données à titre préférentiel.The above-mentioned drying conditions are not critical and are given on a preferential basis.

La taille des particules du fluorure de néodyme peut varier. On le trouve dans le commerce sous forme de poudre dont la taille des particules varie de 40 à 150 µm.
La taille des particules influençant la vitesse de réduction, il est recommandé que la poudre soit fine ce qui peut entraîner une opération de broyage afin que le diamètre moyen des particules de fluorure de nèodyme soit inférieur à 100 µm. Il n'y a aucune limite inférieure de diamètre.The particle size of neodymium fluoride can vary. It is commercially available in the form of a powder, the particle size of which varies from 40 to 150 µm.
The particle size influencing the reduction speed, it is recommended that the powder is fine which can lead to a grinding operation so that the average diameter of the neodymium fluoride particles is less than 100 µm. There is no lower diameter limit.

Le métal réducteur utilisé dans le procédé de l'invention est le calcium.The reducing metal used in the process of the invention is calcium.

Le métal réducteur est mis en oeuvre sous la forme sous laquelle il est commercialisé, qu'il soit à l'état massif ou sous forme de grenailles ou billes.The reducing metal is used in the form in which it is sold, whether it is in the solid state or in the form of pellets or balls.

En ce qui concerne le fer qui intervient dans l'alliage avec le néodyme, il donne un alliage fusible à basse température ce qui rend le procédé industriellement avantageux.As regards the iron which intervenes in the alloy with neodymium, it gives a fusible alloy at low temperature which makes the process industrially advantageous.

On le met en oeuvre sous sa forme telle que commercialisée, poudre ou écailles.It is used in its form as sold, powder or flakes.

Selon l'invention, on ajoute au milieu réactionnel, du chlorure de calcium afin d'abaisser le point de fusion et la densité de la scorie formée dans la réaction de sorte que l'ailiage formé néodyme-fer se sépare plus facilement.According to the invention, calcium chloride is added to the reaction medium in order to lower the melting point and the density of the slag formed in the reaction so that the neodymium-iron formed alloy separates more easily.

On peut utiliser, selon l'invention, les halogénures de calcium disponibles sur le marché : chlorure de calcium anhydre, chlorure de calcium dihydraté qui doit être séché entre 300°C et 400°C sous pression réduite de l'ordre de 1 mm de mercure (= 133,322 Pa) à 100 mm de mercure (= 13 332,2 Pa).Can be used, according to the invention, the calcium halides available on the market: anhydrous calcium chloride, calcium chloride dihydrate which must be dried between 300 ° C and 400 ° C under reduced pressure of the order of 1 mm mercury (= 133,322 Pa) to 100 mm of mercury (= 13,332.2 Pa).

La procédé de l'invention consiste à mélanger un fluorure de néodyme, le calcium. le fer et un chlorure de calcium dans les proportions données ci-dessous.
La quantité de calcium peut varier dans de larges limites. Cependant, il y a intérêt à mettre en oeuvre une quantité suffisante pour réduire le fluorure de néodyme mais elle ne doit pas être trop grande si l'on ne souhaite pas en retrouver, d'une manière importante, dans l'alliage final. La quantité de metal réducteur est au moins égale à la quantité stoechiomètrique voire-même en léger excès, pouvant atteindre 20 % de la quantité stoechiomètrique.
La quantité de fer est réglée suivant la composition désirée de l'alliage. Elle est telle que l'on obtienne un alliage fusible avec le néodyme à la température de réaction. Elle est calculée de sorte que le fer représente de 5 à 30 % du poids de l'alliage obtenu.
La quantité de chlorure de calcium ajoutée est ajustée afin d'obtenir une scorie contenant de 30 à 70 % en poids de chlorure de calcium et de préférence 60 à 70 %.The method of the invention consists in mixing a neodymium fluoride, calcium. iron and calcium chloride in the proportions given below.
The amount of calcium can vary within wide limits. However, it is advantageous to use an amount sufficient to reduce the neodymium fluoride but it should not be too large if one does not wish to find it, in an important way, in the final alloy. The amount of reducing metal is at least equal to the stoichiometric amount or even in slight excess, up to 20% of the stoichiometric amount.
The amount of iron is adjusted according to the desired composition of the alloy. It is such that a fusible alloy with neodymium is obtained at the reaction temperature. It is calculated so that iron represents from 5 to 30% of the weight of the alloy obtained.
The amount of calcium chloride added is adjusted in order to obtain a slag containing from 30 to 70% by weight of calcium chloride and preferably 60 to 70%.

Les différents halogénures de néodyme et de calcium et le fer constituent "une charge" ayant la composition pondérale souhaitée. Les constituants de cette charge peuvent être mis à réagir dans n'importe quel ordre : par mélange simultané de tous les constituants ou en faisant des pré-mélanges, d'une part, les halogénures de néodyme et de calcium et d'autre part le calcium et le fer.The different neodymium and calcium halides and iron constitute "a filler" having the desired weight composition. The constituents of this charge can be reacted in any order: by simultaneous mixing of all the constituents or by making premixes, on the one hand, the neodymium and calcium halides and on the other hand calcium and iron.

La réaction est effectuée à une température comprise entre 800°C et 1100°C. La borne supérieure de température n'a aucun caractère critique et peut atteindre une valeur aussi élevée que 1400°C. D'une manière préférentielle, on choisit une température comprise entre 900°C et 1100°C.The reaction is carried out at a temperature between 800 ° C and 1100 ° C. The upper limit of temperature is not critical and can reach a value as high as 1400 ° C. Preferably, a temperature between 900 ° C and 1100 ° C is chosen.

On effectue la réaction sous pression atmosphérique mais en atmosphère de gaz inerte. A cet effet, on exclut l'air par abaissement de la pression jusqu'à une valeur non critique, par exemple comprise entre 1 mm et 100 mm de mercure puis on assure un balayage de gaz inertes : gaz rares notamment l'argon. Il est souhaitable de soumettre le gaz rare à un traitement de déshydratation et de désoxygénation réalisé selon les techniques usuelles par exemple par passage au travers d'un tamis moléculaire.The reaction is carried out at atmospheric pressure but in an inert gas atmosphere. For this purpose, the air is excluded by lowering from pressure to a non-critical value, for example between 1 mm and 100 mm of mercury, then a scan of inert gases is carried out: rare gases, in particular argon. It is desirable to subject the rare gas to a dehydration and deoxygenation treatment carried out according to the usual techniques, for example by passage through a molecular sieve.

On maintient l'atmosphère inerte tout au cours de la réduction.The inert atmosphere is maintained throughout the reduction.

La durée de la réaction est fonction de la capacité de l'appareillage et de son aptitude à monter rapidement en température. Généralement une fois la température souhaitée atteinte, on la maintient pendant une durée variable d'environ 30 minutes à 3 heures.The duration of the reaction depends on the capacity of the apparatus and its ability to rapidly rise in temperature. Generally once the desired temperature has been reached, it is maintained for a variable period of approximately 30 minutes to 3 hours.

Au cours du chauffage, il se forme deux phases dans le milieu réactionnel : une phase métallique constituée par l'alliage néodyme-fer sur laquelle surnage une scorie constituée de CaF₂-CaCl₂ ayant une densité inférieure à celle de l'alliage.During heating, two phases are formed in the reaction medium: a metallic phase consisting of the neodymium-iron alloy on which floats a slag consisting of CaF₂-CaCl₂ having a density lower than that of the alloy.

Au bout du temps de chauffage précité, on arrête le chauffage.At the end of the above heating time, the heating is stopped.

On peut immédiatement séparer l'alliage de la scorie par coulée à chaud ou le laisser refroidir sous atmosphère de gaz inerte à température ambiante (de 15 à 25°C) de sorte que l'alliage se solidifie et peut être alors démoulé.The alloy can be immediately separated from the slag by hot casting or allowed to cool under an inert gas atmosphere at room temperature (15 to 25 ° C) so that the alloy solidifies and can then be removed from the mold.

On constate que le rendement en néodyme dans l'alliage exprimé par rapport au néodyme contenu dans l'halogénure varie de 80 à 96 %.It can be seen that the yield of neodymium in the alloy expressed relative to the neodymium contained in the halide varies from 80 to 96%.

Le procédé de l'invention tel que décrit, peut être mis en oeuvre dans un appareillage de type classique, utilisé en métallurgie.The method of the invention as described, can be implemented in an apparatus of conventional type, used in metallurgy.

La réduction est conduite dans un creuset placé dans un réacteur constitué par un matériau résistant aux vapeurs fluorhydrique et chlorhydrique.
Il peut être choisi en acier réfractaire, par exemple, en acier contenant 25 % de chrome et 20 % de nickel mais de préférence en inconel qui est un alliage contenant du nickel, du chrome (20 %), du fer (5 %), du molybdène (8-10 %).
Ledit réacteur est équipé d'un dispositif de contrôle de température (par exemple thermocouple), d'une arrivée et d'une sortie de gaz inertes. Il est muni dans sa partie supérieure d'une double enveloppe dans laquelle circule un liquide de refroidissement.
Ce réacteur est placé dans un four à induction ou dans un four chauffé par résistances électriques.
Un creuset dans lequel plonge le dispositif de contrôle de température est placé au fond du réacteur. Il doit être constitué d'un matériau résistant au fluorure de néodyme ou posséder un revêtement leur résistant. D'une manière préférentielle, on utilise un creuset en tantale.The reduction is carried out in a crucible placed in a reactor made of a material resistant to hydrofluoric and hydrochloric vapors.
It can be chosen from refractory steel, for example, steel containing 25% chromium and 20% nickel, but preferably inconel which is an alloy containing nickel, chromium (20%), iron (5%), molybdenum (8-10%).
Said reactor is equipped with a temperature control device (eg thermocouple), an inlet and outlet of inert gases. It is provided in its upper part with a double envelope in which circulates a coolant.
This reactor is placed in an induction furnace or in an furnace heated by electrical resistances.
A crucible in which the temperature control device is immersed is placed at the bottom of the reactor. It must be made of a material resistant to neodymium fluoride or have a coating resistant to them. Preferably, a tantalum crucible is used.

Une fois la réaction effectuée, l'alliage fondu peut être coulé en lingotières, par exemple, en fonte.Once the reaction is complete, the molten alloy can be cast in molds, for example, cast iron.

Les alliages obtenus selon la présente invention ont la composition pondérale suivante :

  • de 70 à 95 % de néodyme
  • de 5 à 30 % de fer
  • moins de 3 % de métal réducteur
The alloys obtained according to the present invention have the following weight composition:
  • 70 to 95% neodymium
  • 5 to 30% iron
  • less than 3% reducing metal

On donne, ci-après, à titre illustratif et non limitatif, des compositions préférées des alliages nèodyme-fer abtenus :

  • . de 83 à 91 % de néodyme
  • . de 9 à 16 % de fer
  • . moins de 1 % de calcium
The following are given, by way of non-limiting illustration, preferred compositions of the neodymium-iron alloys used:
  • . 83 to 91% neodymium
  • . 9 to 16% iron
  • . less than 1% calcium

Les alliages obtenus selon la présente invention sont très riches en néodyme puisqu'ils peuvent en contenir jusqu'a 95%.The alloys obtained according to the present invention are very rich in neodymium since they can contain up to 95%.

Ils peuvent être utilisés comme alliages-mères notamment dans la fabrication d'aimants permanents.They can be used as master alloys in particular in the manufacture of permanent magnets.

Avant de détailler les exemples concrétisant la réalisation pratique de l'invention, on exposera succinctement les méthodes de dosage des différents constituants de l'alliage par les techniques suivantes :

  • le néodyme est dosé, selon la méthode chimique exposée ci-après et consiste :
    • . à dissoudre l'échantillon d'alliage en milieu acide,
    • . à porter à ébullition la solution obtenue,
    • . à précipiter le métal réducteur, le fer et le néodyme sous la forme de leur hydroxyde à pH 9, par traitement à l'ammoniaque, puis à filtrer et laver les précipités obtenus,
    • . à redissoudre le précipité d'hydroxyde de néodyme en milieu acide,
    • . à ajouter à ébullition à la solution obtenue, de l'oxalate d'ammonium afin d'obtenir l'oxalate de néodyme,
    • . à calciner l'oxalate de néodyme à 900°C pendant 1 heure pour le transformer en oxyde,
    • . à peser la quantité d'oxyde obtenu permettant ainsi de calculer la quantité de néodyme contenu dans l'alliage.
  • les autres métaux, métal réducteur et fer sont titrés par absorption atomique.
Before detailing the examples embodying the practical implementation of the invention, the methods for assaying the various constituents of the alloy will be explained briefly by the following techniques:
  • the neodymium is dosed, according to the chemical method set out below and consists of:
    • . dissolving the alloy sample in an acid medium,
    • . bring the solution obtained to a boil,
    • . precipitating the reducing metal, iron and neodymium in the form of their hydroxide at pH 9, by treatment with ammonia, then filtering and washing the precipitates obtained,
    • . redissolving the precipitate of neodymium hydroxide in an acid medium,
    • . adding ammonium oxalate to the solution obtained in boiling to obtain neodymium oxalate,
    • . calcining the neodymium oxalate at 900 ° C for 1 hour to transform it into oxide,
    • . weighing the quantity of oxide obtained, thus making it possible to calculate the quantity of neodymium contained in the alloy.
  • the other metals, reducing metal and iron are titrated by atomic absorption.

On donne, ci-après, un exemple de réalisation de l'invention.An exemplary embodiment of the invention is given below.

Les pourcentages mentionnés dans les exemples sont exprimés en poids.The percentages mentioned in the examples are expressed by weight.

EXEMPLE 1EXAMPLE 1 Préparation d'un alliage néodyme-fer contenant 12 % de ferPreparation of a neodymium-iron alloy containing 12% iron

On commence par broyer, grossièrement, 382,2 g de chlorure de calcium puis on le sèche pendant 3 heures, à une température de 350°C-400°C et sous pression réduite de 1 mm de mercure (= 133,322 Pa).We start by grinding, roughly, 382.2 g of calcium chloride and then drying it for 3 hours, at a temperature of 350 ° C-400 ° C and under reduced pressure of 1 mm of mercury (= 133,322 Pa).

On fait ensuite un prémélange contenant 382,2 g de chlorure de calcium a l'état sec et 281,4 g de fluorure de néodyme ayant un diamètre moyen de particules de 60 µm. On réalise le séchage dudit mélange pendant 24 heures dans une étuve à vide à une température de 225°C et sous pression réduite de 1 mm de mercure (= 133,322 Pa). La charge précédemment définie est alors prête à l'emploi.A premix is then made containing 382.2 g of calcium chloride in the dry state and 281.4 g of neodymium fluoride having an average particle diameter of 60 μm. The drying of said mixture is carried out for 24 hours in a vacuum oven at a temperature of 225 ° C. and under reduced pressure of 1 mm of mercury (= 133.322 Pa). The previously defined load is then ready for use.

La réaction de réduction calciothermique du fluorure de néodyme est réalisée dans un creuset en tantale de 1 litre environ placé au fond d'un réacteur en inconel qui est équipé d'une arrivée et d'une sortie d'argon et d'un thermocouple introduit dans une gaine thermomètrique qui est plongée dans le milieu réactionnel contenu dans le creuset : la partie supérieure du réacteur est munie d'une double enveloppe dans laquelle circule de l'eau froide (environ 10°C).The calciothermic reduction reaction of neodymium fluoride is carried out in a tantalum crucible of about 1 liter placed at the bottom of an inconel reactor which is equipped with an inlet and an argon outlet and a thermocouple introduced into a thermometric sheath which is immersed in the reaction medium contained in the crucible: the upper part of the reactor is provided with a double jacket in which cold water circulates (about 10 ° C).

On définit la proportion des constituants de la charge de telle sorte que les conditions énoncées, ci-après, soient remplies:

  • que l'on obtienne un alliage contenant 12 % de fer
  • que l'on ait un excès de calcium de 20 % par rapport au poids stoechiomètrique requis
  • que l'on forme une scorie contenant 70 % de chlorure de calcium.
The proportion of the constituents of the filler is defined so that the conditions set out below are met:
  • that we obtain an alloy containing 12% iron
  • that there is an excess of calcium of 20% compared to the required stoichiometric weight
  • that a slag containing 70% calcium chloride is formed.

On introduit successivement au fond du creuset 27,5 g de fer sous forme d'écailles, 101 g de calcium sous forme de grenailles et la charge précitée contenant 382,2 g de chlorure de calcium et 281,4 g de fluorure de néodyme.27.5 g of iron in the form of scales, 101 g of calcium in the form of pellets and the aforementioned charge containing 382.2 g of calcium chloride and 281.4 g of neodymium fluoride are successively introduced at the bottom of the crucible.

Une fois le creuset replacé dans le réacteur que l'on ferme, on abaisse la pression aux environs de 100 mm de mercure (= 13 332,2 Pa) pour chasser l'air puis on établit un balayage à l'argon sec qui sera maintenu tout au long de la réaction.Once the crucible has been replaced in the closed reactor, the pressure is lowered to around 100 mm of mercury (= 13,332.2 Pa) to expel the air, then a dry argon sweep is established, which will be maintained throughout the reaction.

On effectue en même temps une montée en température jusqu'à obtention de la température fixée à 1100°C ; cette température étant tenue constante encore 30 minutes.A temperature rise is carried out at the same time until the temperature fixed at 1100 ° C. is obtained; this temperature being kept constant for another 30 minutes.

On recueille 562 g de scorie et on récupère 188 g d'un alliage néodyme-fer par coulage à chaud dans une lingotière en fonte. Le rendement en néodyme dans l'alliage exprimé par rapport au néodyme contenu dans le fluorure de néodyme est de 81 %.562 g of slag are collected and 188 g of a neodymium-iron alloy are recovered by hot casting in a cast iron ingot mold. The neodymium yield in the alloy expressed relative to the neodymium contained in the neodymium fluoride is 81%.

L'analyse de l'alliage obtenu est la suivante :

  • 87,4 % de néodyme
  • 12 % de fer
  • 0,6 % de calcium.
The analysis of the alloy obtained is as follows:
  • 87.4% neodymium
  • 12% iron
  • 0.6% calcium.

Claims (12)

  1. Verfahren zur Herstellung von Legierungen aus Neodym und Eisen, bei dem ein Neodymfluorid mit Calcium in Gewgenwart von Eisen reduziert wird, dadurch gekennzeichnet, daß die Menge an Eisen so definiert wird, daß die Neodym-Eisenlegierung einen Eisengehalt von 5 bis 30% aufweist und daß man dem Reaktionsmedium Calciumchlorid zusetzt.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß man das Neodymfluorid bei 100 bis 500°C an der Luft oder unter einem verminderten Druck von 1 bis 100 mm Quecksilber trocknet.
  3. Verfahren nach einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, daß man das Calciumchlorid bei 300 bis 400°C unter vermindertem Druck von 1 bis 100 mm Quecksilber trocknet.
  4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß die Menge an Calcium gleich ist der stöchiometrischen Menge oder einen leichten Überschuß bis zu 20% der stöchiometrischen Menge ausmacht.
  5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Menge an Eisen so ist, daß man eine Legierung mit 9 bis 16% Eisen erhält.
  6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß man soviel Calciumchlorid zusetzt, daß man eine Schlacke erhält, die 30 bis 70% Calciumchlorid enthält.
  7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, daß man soviel Calciumchlorid zusetzt, daß man eine Schlacke erhält, die 60 bis 70% Calciumchlorid enthält.
  8. Verfahren nach einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, daß man die Reaktion bei 800 bis 1100°C unter Atmosphärendruck, aber in Inertgasatmosphäre durchführt.
  9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, daß man die Reaktion bei 900 bis 1100°C durchführt.
  10. Verfahren nach Anspruch 8, dadurch gekennzeichnet, daß man eine Inertgasatmosphäre durch Luftausschluß und anschließendes Spülen mit trockenem Argon erzeugt.
  11. Verfahren nach Anspruch 8 oder 9, dadurch gekennzeichnet, daß man die gewählte Temperatur während einer Zeitspanne von 30 min bis zu 3 h beibehält.
  12. Verfahren nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet, daß man nach beendeter Reaktion die erhaltene Legierung von der Schlacke trennt, entweder durch Heißguß oder durch Entformen nach Abkühlen unter einer Inertgasatmosphäre.
EP88100014A 1983-07-05 1984-06-22 Process for the production of neodym alloys Expired - Lifetime EP0272250B1 (en)

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FR8311139A FR2548687B1 (en) 1983-07-05 1983-07-05 NEODYM ALLOYS AND THEIR MANUFACTURING METHOD
FR8311139 1983-07-05
FR838314392A FR2551769B2 (en) 1983-07-05 1983-09-09 NEODYM ALLOYS AND THEIR MANUFACTURING METHOD
FR8314392 1983-09-09

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FR2551769B2 (en) 1990-02-02
JPS6046346A (en) 1985-03-13
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DE3485950D1 (en) 1992-11-05
FR2551769A2 (en) 1985-03-15
KR920006603B1 (en) 1992-08-10
AU579579B2 (en) 1988-12-01
EP0272250A1 (en) 1988-06-22
DE3479595D1 (en) 1989-10-05
AU3008184A (en) 1985-01-10

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