EP0134162B1 - Alloys of neodymium and process for their production - Google Patents

Alloys of neodymium and process for their production Download PDF

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Publication number
EP0134162B1
EP0134162B1 EP84401307A EP84401307A EP0134162B1 EP 0134162 B1 EP0134162 B1 EP 0134162B1 EP 84401307 A EP84401307 A EP 84401307A EP 84401307 A EP84401307 A EP 84401307A EP 0134162 B1 EP0134162 B1 EP 0134162B1
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Prior art keywords
neodymium
metal
process according
halide
calcium
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EP84401307A
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German (de)
French (fr)
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EP0134162A1 (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
Application filed by Rhone Poulenc Chimie SA filed Critical Rhone Poulenc Chimie SA
Priority to AT84401307T priority Critical patent/ATE45989T1/en
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    • 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
    • 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

Definitions

  • the present invention relates to neodymium alloys and their manufacturing process.
  • 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 have new neodymium alloys obtained according to an industrial manufacturing process.
  • the rare earth metal involved in said alloys is therefore any metal belonging to the group formed by yttrium and lanthanides, except samarium, europium and ytterbium.
  • a “rare earth metal” or a mixture of rare earth metals chosen from the group defined above will be simplifiedly designated by “metal TR”.
  • neodymium halide neodymium fluoride or neodymium chloride or a mixture thereof is used.
  • neodymium fluoride is used.
  • the halide used is 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%.
  • Neodymium fluoride is available in an anhydrous state because it is a low hygroscopic product.
  • neodymium chloride exists in the form of hydrates containing 6 to 7 moles of water per mole of neodymium chloride. It is generally prepared by the reaction of hydrochloric acid and neodymium sesquioxide.
  • this chloride requires a drying step at a temperature between 100 ° C and 500 ° C but preferably between 200 ° C and 250 ° C.
  • This treatment is also suitable for neodymium fluoride.
  • the drying time can vary between 2 and 24 hours.
  • the particle size of the neodymium halide may 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 particles of neodymium halide is less than 100 wm. There is no lower diameter limit.
  • halide of. TR metal you can choose a TR metal fluoride, a TR metal chloride or their mixture.
  • the fluoride of the metal TR is used.
  • the properties required and the conditions for using the metal halide TR are identical to those of the neodymium halide.
  • the reducing metal used in the process of the invention can be an alkali metal, an alkaline earth metal or a mixture thereof. Mention may be made, as alkali metal, of sodium, lithium or potassium and, as alkaline earth metal, of calcium or magnesium.
  • Calcium or magnesium is preferably used and even more preferably calcium.
  • the reducing metal is used in the form in which it is sold, whether it is in the state solid or in the form of pellets or balls.
  • a preferred variant of the process of the invention consists in adding to the reaction medium calcium chloride or calcium fluoride as the case may be in order to lower the melting point and the density of the slag formed in the reaction so that the formed alloy neodymium-iron separates more easily.
  • the aim being to obtain a CaF 2 -CaCI 2 slag, the addition when the source of neodymium is neodymium fluoride or neodymium chloride, respectively calcium chloride or calcium fluoride. If the neodymium halide is a mixture of fluoride and chloride, a mixture of chloride and calcium fluoride is added in order to obtain a CaF 2 -CaCI 2 mixture having the composition defined later.
  • calcium chloride should be added when using neodymium fluoride and a metal fluoride TR and calcium fluoride when using uses neodymium chloride and a metal chloride TR. If the neodymium halide or TR metal is a mixture of fluoride and chloride or if the neodymium halides and TR metal are different in nature, it is necessary to add a CaF 2 -CaCIp mixture in order to have the desired composition.
  • the process of the invention consists in mixing a neodymium halide, a metal halide TR, a reducing metal, iron and optionally a calcium halide in the proportions given below. '°
  • the quantity of TR metal halide used is calculated according to the composition of the desired alloy. It will preferably be defined so that the metal TR represents less than 50% of the weight of the mixture consisting of neodymium and the metal TR and more preferably still less than 10%.
  • the amount of reducing metal can vary within wide limits. However, it is advantageous to use a quantity sufficient to reduce the neodymium halide and possibly the metal halide TR but it should not be too large if one does not wish to find it, of a importantly, 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 and iron 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 halide 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 various halides of neodymium, of metal TR and of calcium and the abovementioned metals 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 halides of neodymium, calcium, metal TR and d on the other hand the reducing metal and iron.
  • the reaction is carried out at a temperature between 800 ° C and 1100 ° C.
  • the upper temperature limit 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.
  • rare gases including 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 is reached, it is maintained for a variable duration of approximately 30 minutes to 3 hours.
  • a metallic phase consisting of the neodymium-iron alloy on which floats a slag consisting of CaF 2 -CaCI 2 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 rare earth metals (neodymium + metal TR) expressed relative to to the rare earth metals contained in the halides used varies from 75 to 95%.
  • the reduction is carried out in a crucible placed in a reactor made of a material resistant to hydrofluoric and hydrochloric vapors.
  • 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 (for example thermocouple), an inlet and an outlet for inert gases. It is provided in its upper part with a double envelope in which circulates a coolant.
  • a temperature control device for example thermocouple
  • 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 halides or have a coating resistant to them. Preferably, a tantalum crucible is used.
  • the molten alloy can be cast in molds, for example, cast iron.
  • the proportion of TR metal can represent less than 50% of the weight of the mixture constituted by neodymium and TR metal and, preferably, less than 10%.
  • 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 containing 530.8 g of calcium chloride in the dry state and 390.8 g of a mixture containing 96.4% of neodymium fluoride and 3.6% of praseodymium fluoride is then made: said mixture having an average particle diameter of 60 ⁇ m.
  • the calciothermic reduction reaction of neodymium fluoride and praseodymium fluoride is carried out in a tantalum crucible of about 1 liter placed at the bottom of an inconel reactor which is equipped of an inlet and an outlet of argon and of 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 envelope in which circulates cold water (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.
  • 717.2 g of slag are collected and 296 g of a neodymium-praseodymium-iron alloy are recovered by hot casting in a cast iron ingot mold.
  • the yield of rare earths in the alloy expressed relative to the rare earths contained in neodymium and praseodymium fluorides is 90%.
  • Example 2 is reproduced, except that a mixture of neodymium fluoride and praseodymium fluoride is used, but a mixture containing 58% of neodymium chloride and 42% of praseodymium chloride.

Description

La présente invention a trait à des alliages de néodyme et leur procédé de fabrication.The present invention relates to neodymium alloys and their manufacturing process.

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'apparaît 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 » O. 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 ”O. 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.

L'objectif de la présente invention est de disposer de nouveaux alliages de néodyme obtenus selon un procédé industriel de fabrication.The objective of the present invention is to have new neodymium alloys obtained according to an industrial manufacturing process.

L'un. des objets de la présente invention réside dans de nouveaux alliages de néodyme consistant en néodyme, fer et au moins un métal d'une autre terre rare choisie dans le groupe formé par l'yttrium, le lanthane, le cérium, le praséodyme, le gadolinium, le terbium, le dysprosium, l'holmium, l'erbium, le thulium, le lutécium et mis en oeuvre dans les proportions suivantes :

  • de 70 à 95 % d'un mélange de néodyme et de métal de terre rare
  • de" 5 à 30 % de fer
  • de 0 à 3 % de métal réducteur
Mon. objects of the present invention resides in new neodymium alloys consisting of neodymium, iron and at least one metal of another rare earth chosen from the group formed by yttrium, lanthanum, cerium, praseodymium, gadolinium , terbium, dysprosium, holmium, erbium, thulium, lutetium and used in the following proportions:
  • 70 to 95% of a mixture of neodymium and rare earth metal
  • "5 to 30% iron
  • 0 to 3% reducing metal

Le métal d'une terre rare intervenant dans lesdits alliages est donc tout métal appartenant au groupe formé par l'yttrium et les lanthanides excepté le samarium, l'europium et l'ytterbium.The rare earth metal involved in said alloys is therefore any metal belonging to the group formed by yttrium and lanthanides, except samarium, europium and ytterbium.

Dans l'exposé qui suit de l'invention, on dénommera de manière simplifiée, par « métal TR » un métal d'une terre rare ou un mélange de métaux de terres rares choisis dans le groupe précédemment défini.In the following description of the invention, a “rare earth metal” or a mixture of rare earth metals chosen from the group defined above will be simplifiedly designated by “metal TR”.

Dans le procédé de fabrication des alliages précités, intervient un halogénure de néodyme.In the process for manufacturing the above-mentioned alloys, a neodymium halide is involved.

Comme halogénure de néodyme, on utilise le fluorure de néodyme ou le chlorure de néodyme ou leur mélange.As neodymium halide, neodymium fluoride or neodymium chloride or a mixture thereof is used.

D'une manière préférentielle, on emploie le fluorure de néodyme.Preferably, neodymium fluoride is used.

Il est souhaitable que l'halogénure mis en oeuvre 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 the halide used is 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.

Par contre, le chlorure de néodyme existe sous forme d'hydrates contenant 6 à 7 moles d'eau par mole de chlorure de néodyme. Il est préparé généralement, par réaction de l'acide chlorhydrique et du sesquioxyde de néodyme.On the other hand, neodymium chloride exists in the form of hydrates containing 6 to 7 moles of water per mole of neodymium chloride. It is generally prepared by the reaction of hydrochloric acid and neodymium sesquioxide.

La mise en oeuvre de ce chlorure nécessite 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). Ce traitement convient également au fluorure de néodyme.The implementation of this chloride requires 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). This treatment is also suitable for neodymium fluoride.

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 de l'halogénure de néodyme ne présentent aucun caractère critique et sont données à titre préférentiel.The conditions set out above for drying the neodymium halide are not critical and are given on a preferential basis.

La taille des particules de l'halogénure de néodyme peut varier. On le trouve dans le commerce sous forme de poudre dont la taille des particules varie de 40 à 150 Pm.The particle size of the neodymium halide may vary. It is commercially available in the form of a powder, the particle size of which varies from 40 to 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 l'halogénure de néodyme soit inférieur à 100 wm. Il n'y a aucune limite inférieure de diamètre.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 particles of neodymium halide is less than 100 wm. There is no lower diameter limit.

Pour ce qui est de l'halogénure du. métal TR, on peut choisir un fluorure de métal TR, un chlorure de métal TR ou leur mélange.As for the halide of. TR metal, you can choose a TR metal fluoride, a TR metal chloride or their mixture.

D'une manière préférentielle, on emploie le fluorure du métal TR.Preferably, the fluoride of the metal TR is used.

Les propriétés requises et les conditions de mise en oeuvre de l'halogénure du métal TR sont identiques à celles de l'halogénure de néodyme.The properties required and the conditions for using the metal halide TR are identical to those of the neodymium halide.

Compte tenu de ce qui est mentionné précédemment, il est possible de faire appel à un mélange d'halogénures de différents métaux de terres rares.In view of what is mentioned above, it is possible to use a mixture of halides of different rare earth metals.

Le métal réducteur utilisé dans le procédé de l'invention peut être un métal alcalin, un métal alcalino-terreux ou leur mélange. Comme métal alcalin, on peut citer le sodium, le lithium ou le potassium et comme métal alcalino-terreux, le calcium ou le magnésium.The reducing metal used in the process of the invention can be an alkali metal, an alkaline earth metal or a mixture thereof. Mention may be made, as alkali metal, of sodium, lithium or potassium and, as alkaline earth metal, of calcium or magnesium.

On emploie de préférence le calcium ou le magnésium et encore plus préférentiellement, le calcium.Calcium or magnesium is preferably used and even more preferably 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 state solid 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 la forme telle que commercialisée, poudre ou écailles.It is used in the form as sold, powder or flakes.

Une variante préférée du procédé de l'invention consiste à ajouter au milieu réactionnel du chlorure de calcium ou du fluorure de calcium selon le cas afin d'abaisser le point de fusion et la densité de la scorie formée dans la réaction de sorte que l'alliage formé néodyme-fer se sépare plus facilement.A preferred variant of the process of the invention consists in adding to the reaction medium calcium chloride or calcium fluoride as the case may be in order to lower the melting point and the density of the slag formed in the reaction so that the formed alloy neodymium-iron separates more easily.

Le but étant d'obtenir une scorie CaF2-CaCI2, on additionne lorsque la source de néodyme est le fluorure de néodyme ou le chlorure de néodyme, respectivement du chlorure de calcium ou du fluorure de calcium. Si l'halogénure de néodyme est un mélange de fluorure et de chlorure, on ajoute un mélange de chlorure et fluorure de calcium afin d'obtenir un mélange CaF2-CaCI2 ayant la composition définie ultérieurement.The aim being to obtain a CaF 2 -CaCI 2 slag, the addition when the source of neodymium is neodymium fluoride or neodymium chloride, respectively calcium chloride or calcium fluoride. If the neodymium halide is a mixture of fluoride and chloride, a mixture of chloride and calcium fluoride is added in order to obtain a CaF 2 -CaCI 2 mixture having the composition defined later.

Dans le cas où il y a présence d'un halogénure de métal T.R., il y a lieu d'additionner du chlorure de calcium lorsque l'on utilise le fluorure de néodyme et un fluorure de métal TR et du fluorure de calcium lorsqu'on fait appel au chlorure de néodyme et à un chlorure de métal TR. Si l'halogénure de néodyme ou du métal TR est un mélange de fluorure et de chlorure ou si les halogénures de néodyme et du métal TR sont de nature différente, il est nécessaire d'ajouter un mélange CaF2-CaCIp afin d'avoir la composition souhaitée.In the case where there is a metal halide TR, calcium chloride should be added when using neodymium fluoride and a metal fluoride TR and calcium fluoride when using uses neodymium chloride and a metal chloride TR. If the neodymium halide or TR metal is a mixture of fluoride and chloride or if the neodymium halides and TR metal are different in nature, it is necessary to add a CaF 2 -CaCIp mixture in order to have the desired composition.

On peut utiliser, selon l'invention, les halogénures de calcium disponibles sur le marché : fluorure de calcium et 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: calcium fluoride and anhydrous calcium chloride, calcium chloride dihydrate which must be dried between 300 ° C and 400 ° C under reduced pressure of the order from 1 mm of mercury (= 133,322 Pa) to 100 mm of mercury (= 13,332.2 Pa).

Le procédé de l'invention consiste à mélanger un halogénure de néodyme, un halogénure de métal TR, uri métal réducteur, le fer et éventuellement un halogénure de calcium dans les proportions données ci-dessous. ' °The process of the invention consists in mixing a neodymium halide, a metal halide TR, a reducing metal, iron and optionally a calcium halide in the proportions given below. '°

La quantité de l'halogénure du métal TR engagée est calculée en fonction de la composition de l'alliage souhaitée. Elle sera définie, de préférence, de telle sorte que le métal TR représente moins de 50 % du poids du mélange constitué par le néodyme et- le métal TR et encore, plus préférentiellement, moins de 10 %.The quantity of TR metal halide used is calculated according to the composition of the desired alloy. It will preferably be defined so that the metal TR represents less than 50% of the weight of the mixture consisting of neodymium and the metal TR and more preferably still less than 10%.

La quantité de métal réducteur peut varier dans de larges limites. Cependant, il y a intérêt à en mettre en œuvre une quantité suffisante pour réduire l'halogénure de néodyme et éventuellement l'halogénure de métal TR 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 métal réducteur est au moins égale à la quantité stoechiométrique voire-même en léger excès, pouvant atteindre 20 % de la quantité stoechiométrique.The amount of reducing metal can vary within wide limits. However, it is advantageous to use a quantity sufficient to reduce the neodymium halide and possibly the metal halide TR but it should not be too large if one does not wish to find it, of a importantly, 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.

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 et le fer à la température de réaction. Elle est calculée de sorte que le fer représente de 5 à 30 % du poids de l'alliage obtenu.The amount of iron is adjusted according to the desired composition of the alloy. It is such that a fusible alloy with neodymium and iron is obtained at the reaction temperature. It is calculated so that iron represents from 5 to 30% of the weight of the alloy obtained.

La quantité d'halogénure 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 amount of calcium halide 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, de métal TR et de calcium et les métaux précités 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, de calcium, de métal TR et d'autre part le métal réducteur et le fer.The various halides of neodymium, of metal TR and of calcium and the abovementioned metals 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 halides of neodymium, calcium, metal TR and d on the other hand the reducing metal and iron.

La réaction est effectuée à une température comprise entre 800 °C et 1 100°C. La borne supérieure de température n'a aucun caractère critique et peut atteindre une valeur aussi élevée que 1 400 °C. D'une manière préférentielle, on choisit une température comprise entre 900 °C et 1 100 °C.The reaction is carried out at a temperature between 800 ° C and 1100 ° C. The upper temperature limit 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 de mercure (= 133,322 Pa) et 100 mm de mercure (= 13 332,2 Pa) 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 the pressure to a non-critical value, for example between 1 mm of mercury (= 133.322 Pa) and 100 mm of mercury (= 13.332.2 Pa) and then ensures inert gas sweeping: rare gases including 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 is reached, it is maintained for a variable duration 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-CaCI2 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 CaF 2 -CaCI 2 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 métaux de terres rares (néodyme + métal TR) exprimé, par rapport aux métaux de terres rares contenus dans les halogénures engagés varie de 75 à 95 %.It can be seen that the yield of rare earth metals (neodymium + metal TR) expressed relative to to the rare earth metals contained in the halides used varies from 75 to 95%.

Le procédé de l'invention tel que décrit, peut être mis en oeuvre dans un appareillage de type classique, utilisé en métallurgie.The process 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.The reduction is carried out in a crucible placed in a reactor made of a material resistant to hydrofluoric and hydrochloric vapors.

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 %).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%).

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.Said reactor is equipped with a temperature control device (for example thermocouple), an inlet and an outlet for inert gases. It is provided in its upper part with a double envelope in which circulates a coolant.

Ce réacteur est placé dans un four à induction ou dans un four chauffé par résistances électriques.This reactor is placed in an induction furnace or in an furnace heated by electrical resistances.

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 aux halogénures de néodyme ou posséder un revêtement leur résistant. D'une manière préférentielle, on utilise un creuset en tantale.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 halides 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 % d'un mélange de néodyme et de métal TR
  • - de 5 à 30 % de fer.
The alloys obtained according to the present invention have the following weight composition:
  • - from 70 to 95% of a mixture of neodymium and TR metal
  • - from 5 to 30% iron.

Dans le mélange de néodyme et du métal TR, la proportion de métal TR peut représenter moins de 50 % du poids du mélange constitué par le néodyme et le métal TR et, de préférence, moins de 10 %.In the mixture of neodymium and TR metal, the proportion of TR metal can represent less than 50% of the weight of the mixture constituted by neodymium and TR metal and, preferably, less than 10%.

On note également la présence d'une très faible quantité de métal réducteur allant de 0 à 3 % en poids.We also note the presence of a very small amount of reducing metal ranging from 0 to 3% by weight.

On donne, ci-après, à titre illustratif et non limitatif, des compositions préférées des alliages obtenus : alliage néodyme-fer-métal TR

  • de 83 à 91 % d'un mélange de néodyme et de métal TR
  • de 9 à 16 % de fer
  • de 0 à 3 % de calcium
Preferred compositions of the alloys obtained are given hereinafter by way of illustration and without implied limitation: neodymium-iron-metal alloy TR
  • 83 to 91% of a mixture of neodymium and metal TR
  • 9 to 16% iron
  • 0 to 3% calcium

Les alliages obtenus selon la présente invention sont très riches en néodyme puisqu'ils peuvent en contenir jusqu'à 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 et l'autre métal d'une terre rare lorsqu'il est présent sont dosés, ensemble, selon la méthode chimique exposée ci-après et séparément, par fluorescence X. La méthode chimique de dosage 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 les terres rares 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'hydroxydes de terres rares en milieu acide,
    • à ajouter à ébullition à la solution obtenue, de l'oxalate d'ammonium afin d'obtenir les oxalates de terres rares,
    • à calciner les oxalates de terres rares à 900 °C pendant 1 heure pour les transformer en oxyde,
    • à peser la quantité d'oxydes obtenus permettant ainsi de calculer la quantité de terres rares contenus 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 and the other rare earth metal when it is present are assayed together, according to the chemical method set out below and separately, by X-ray fluorescence. The chemical assay method consists:
    • dissolving the alloy sample in an acid medium,
    • bring the solution obtained to a boil,
    • to precipitate the reducing metal, iron and rare earths in the form of their hydroxide at pH 9, by treatment with ammonia, then to filter and wash the precipitates obtained,
    • redissolving the precipitate of rare earth hydroxides in an acid medium,
    • adding ammonium oxalate to the solution obtained in boiling in order to obtain the rare earth oxalates,
    • calcining the rare earth oxalates at 900 ° C for 1 hour to transform them into oxide,
    • weighing the quantity of oxides obtained, thus making it possible to calculate the quantity of rare earths contained in the alloy,
    • the other metals, reducing metal and iron are titrated by atomic absorption.

Dans l'exposé qui suit de l'invention, on donne deux exemples de préparation d'un alliage néodyme-praséodyme-fer (exemples 1 et 2).In the following description of the invention, two examples of the preparation of a neodymium-praseodymium-iron alloy are given (examples 1 and 2).

Exemple 1Example 1 Préparation d'un alliage néodyme-praséodyme-fer contenant 13 % de ferPreparation of a neodymium-praseodymium-iron alloy containing 13% iron

On commence par broyer, grossièrement, 530,8 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, 530.8 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 530,8 g de chlorure de calcium à l'état sec et 390,8 g d'un mélange contenant 96,4 % de fluorure de néodyme et 3,6 % de fluorure de praséodyme : ledit mélange ayant un diamètre moyen de particules de 60 flom. 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 containing 530.8 g of calcium chloride in the dry state and 390.8 g of a mixture containing 96.4% of neodymium fluoride and 3.6% of praseodymium fluoride is then made: said mixture having an average particle diameter of 60 µm. The drying of the said mixture is carried out for 24 hours in a vacuum oven at a temperature of 225 ° C. and under a pressure reduced by 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 et du fluorure de praséodyme 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 gaîne thermométrique 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 and praseodymium fluoride is carried out in a tantalum crucible of about 1 liter placed at the bottom of an inconel reactor which is equipped of an inlet and an outlet of argon and of 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 envelope in which circulates cold water (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 13 % de fer
  • que l'on ait un excès de calcium de 20 % par rapport au poids stoechiométrique 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 13% 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, 38,2 g de fer sous forme d'écailles, 140,3 g de calcium sous forme de grenailles et la charge précitée contenant 530,8 g de chlorure de calcium et 390,8 g d'un mélange de fluorure de néodyme et de fluorure de praséodyme.38.2 g of iron in the form of scales, 140.3 g of calcium in the form of pellets and the abovementioned charge containing 530.8 g of calcium chloride and 390.8 g of a mixture of neodymium fluoride and praseodymium fluoride.

Une fois le creuset replacé dans le réacteur que l'on ferme, on abaisse la pression aux environs de 100 mm de mercure (= 13332,2 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 1 100 °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 717,2 g de scorie et on récupère 296 g d'un alliage néodyme-praséodyme-fer, par coulage à chaud dans une lingotière en fonte. Le rendement en terres rares dans l'alliage exprimé par rapport aux terres rares contenues dans les fluorures de néodyme et de praséodyme est de 90 %.717.2 g of slag are collected and 296 g of a neodymium-praseodymium-iron alloy are recovered by hot casting in a cast iron ingot mold. The yield of rare earths in the alloy expressed relative to the rare earths contained in neodymium and praseodymium fluorides is 90%.

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

  • 86 % d'un mélange contenant 96,4 % de néodyme et 3,6 % de praséodyme
  • 13 % de fer
  • . 1 % de calcium.
The analysis of the alloy obtained is as follows:
  • 86% of a mixture containing 96.4% of neodymium and 3.6% of praseodymium
  • 13% iron
  • . 1% calcium.

Exemple 2Example 2 Préparation d'un alliage néodyme-praséodyme-fer contenant 13 % de ferPreparation of a neodymium-praseodymium-iron alloy containing 13% iron

On reproduit l'exemple 2 à la différence près que l'on met en oeuvre non pas un mélange de fluorure de néodyme et de fluorure de praséodyme mais un mélange contenant 58 % de chlorure de néodyme et 42 % de chlorure de praséodyme. Dans ce cas, les chlorures de néodyme et de praséodyme sont séchés pendant 3 heures dans une étuve à vide à une température de 220 °C et sous pression réduite de 1 mm de mercure (= 133,322 Pa).Example 2 is reproduced, except that a mixture of neodymium fluoride and praseodymium fluoride is used, but a mixture containing 58% of neodymium chloride and 42% of praseodymium chloride. In this case, the neodymium and praseodymium chlorides are dried for 3 hours in a vacuum oven at a temperature of 220 ° C. and under pressure reduced by 1 mm of mercury (= 133.322 Pa).

La charge mise en oeuvre selon le même mode opératoire est la suivante :

  • 39,3 g de fer
  • 144 g de calcium
  • 142,7 g de fluorure de calcium
  • 498,6 g d'un mélange de chlorure de néodyme et de chlorure de praséodyme.
The charge implemented according to the same operating mode is as follows:
  • 39.3 g iron
  • 144 g calcium
  • 142.7 g of calcium fluoride
  • 498.6 g of a mixture of neodymium chloride and praseodymium chloride.

A la fin de la réaction, on obtient 519 g de scorie et 275 g d'un alliage néodyme-praséodyme-fer ce qui correspond à un rendement en terres rares de 81 %.At the end of the reaction, 519 g of slag and 275 g of a neodymium-praseodymium-iron alloy are obtained, which corresponds to a rare earth yield of 81%.

L'alliage obtenu contient :

  • 84 % d'un mélange contenant 58 % de néodyme et 42 % de praséodyme
  • 13 % de fer
  • 3 % de calcium
The alloy obtained contains:
  • 84% of a mixture containing 58% neodymium and 42% praseodymium
  • 13% iron
  • 3% calcium

Claims (23)

1. New neodymium alloys consisting of neodymium, iron and at least one other rare earth metal chosen from the group consisting of yttrium, lanthanum, cerium, praseodymium, gadolinium, terbium, dysprosium, holmium, erbium, thulium and lutecium and employed in the following proportions :
from 70 to 95 % of a mixture of neodymium and rare earth metal
from 5 to 30 % of iron and
from 0 to 3 % of reducing metal.
2. Neodymium alloys according to Claim 1, characterised in that the RE metal is praseodymium.
3. Neodymium alloys according to one of Claims 1 and 2, characterised in that they consist of
83 to 91 % of a mixture of neodymium and RE metal
9 to 16 % of iron and
0 to 3 % of calcium.
4. Neodymium alloys according to one of Claims 1 to 3, characterised in that the proportion of RE metal represents less than 50 % of the weight of the mixture consisting of neodymium and RE metal.
5. Neodymium alloys according to Claim 4, characterised in that the proportion of RE metal represents less than 10 % of the weight of the metal consisting of neodymium and RE metal.
6. Process for the manufacture of the alloys described in one of Claims 1 to 4, characterised in that it consists of reducing a neodymium halide and an RE metal halide with a reducing metal in the presence of iron.
7. Process according to Claim 6, characterised in that the neodymium halide is neodymium fluoride, neodymium chloride or a mixture of these.
8. Process according to Claim 7, characterised in that the neodymium halide is dried at between 100°C and 500 °C in air or under a reduced pressure of between 1 mm of mercury (= 133.322 Pa) and 100 mm of mercury (= 13,332.2 Pa).
9. Process according to Claim 6, characterised in that the reducing metal is an alkali metal such as sodium, lithium or potassium or an alkaline earth metal such as calcium or magnesium.
10. Process according to Claim 4, characterised in that the reducing metal is calcium.
11. Process according to Claim 6, characterised in that the RE metal halide is dried at between 100°C and 500 °C in air or under a reduced pressure of between 1 mm of mercury (= 133.322 Pa) and 100 mm of mercury (= 13,332.2 Pa).
12. Process according to one of Claims 6 to 11, characterised in that calcium chloride is added to the reaction mixture if neodymium fluoride and an RE metal fluoride are employed, calcium fluoride is added to the reaction mixture if neodymium chloride and an RE metal chloride are employed, and a mixture of calcium fluoride and calcium chloride is added to the reaction mixture if the neodymium halide or RE metal halide is a mixture of flubride and chloride or if the neodymium halide and RE metal halide are of different natures.
13. Process according to Claim 12, characterised in that the calcium halide is dried at between 300 °C and 400 °C under a reduced pressure of 1 mm of mercury (= 133.322 Pa) to 100 mm of mercury (= 13,332.2 Pa).
14. Process according to one of Claims 6 to 13, characterised in that the amount of RE metal halide is such that in the alloy obtained the proportion of RE metal represents less than 50 % of the weight of the mixture consisting of neodymium and RE metal.
15. Process according to Claim 14, characterised in that the amount of RE metal halide is such that in the alloy obtained the proportion of RE metal represents less than 10 % of the weight of the mixture consisting of neodymium and RE metal.
16. Process according to one of Claims 6 to 15, characterised in that the amount of reducing metal is equal to the stoichiometric amount or is used in a slight excess which can be as much as 20 % of the stoichiometric amount.
17. Process according to one of Claims 6 to 16, characterised in that the amount of calcium halide added is such that a slag containing from 30 to 70 % of calcium chloride is obtained.
18. Process according to Claim 17, characterised in that the amount of calcium halide added is such that a slag containing from 60 to 70 % of calcium chloride is obtained.
19. Process according to one of Claims 6 to 18, characterised in that the reaction is carried out at between 800 °C and 1 100 °C under atmospheric pressure, but in an inert gas atmosphere.
20. Process according to Claim 19, characterised in that the reaction is carried out at between 900 °C and 1 100°C.
21. Process according to Claim 19, characterised in that an inert gas atmosphere is set up by removing air and then sweeping with dry argon.
22. Process according to Claim 19 or 20, characterised in that the chosen temperature is maintained for a period ranging from 30 minutes to 3 hours.
23. Process according to one of Claims 6 to 22, characterised in that at the end of the reaction the alloy obtained is separated from the slag either by hot casting or by stripping after cooling under an inert gas atmosphere.
EP84401307A 1983-07-05 1984-06-22 Alloys of neodymium and process for their production Expired EP0134162B1 (en)

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EP0272250B1 (en) 1992-09-30
BR8403289A (en) 1985-06-18
DE3485950T2 (en) 1993-02-25
KR850001297A (en) 1985-03-18
JPH0224902B2 (en) 1990-05-31
CA1253721A (en) 1989-05-09
US4636353A (en) 1987-01-13
FR2551769B2 (en) 1990-02-02
JPS6046346A (en) 1985-03-13
EP0134162A1 (en) 1985-03-13
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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