EP0273835B1 - Procédé d'élaboration par métallothermie d'alliages purs à base de terres rares et de métaux de transition - Google Patents

Procédé d'élaboration par métallothermie d'alliages purs à base de terres rares et de métaux de transition Download PDF

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Publication number
EP0273835B1
EP0273835B1 EP87420319A EP87420319A EP0273835B1 EP 0273835 B1 EP0273835 B1 EP 0273835B1 EP 87420319 A EP87420319 A EP 87420319A EP 87420319 A EP87420319 A EP 87420319A EP 0273835 B1 EP0273835 B1 EP 0273835B1
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EP
European Patent Office
Prior art keywords
process according
reaction mixture
compound
rare earth
crucible
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP87420319A
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German (de)
English (en)
French (fr)
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EP0273835A1 (fr
Inventor
Alex Jourdan
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Comurhex pour La Conversion de lUranium en Metal et Hexafluorure SA
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Comurhex pour La Conversion de lUranium en Metal et Hexafluorure SA
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Classifications

    • 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
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/003—Making ferrous alloys making amorphous alloys

Definitions

  • the invention relates to an industrial process for the production of pure rare earth alloys and transition metals and possibly other additions in small quantities, by metallothermic reduction of their compounds (halides, oxides, etc.).
  • This process is mainly applied to the preparation of mother alloy for the manufacture of permanent magnets based on rare earths, mainly neodymium-iron-boron magnets.
  • rare earth compounds including Yttrium, having a positive degree of oxidation, particularly oxides and / or halides, by an alkali or alkaline earth metal, is well known.
  • the application of this reaction is known for obtaining mother alloys of rare earths, iron (or other transition metals such as cobalt, nickel, etc.), boron, which may also contain other elements, from a rare earth compound to which Fe and / or Boron have been mixed, the boron can also be introduced in the form of ferro-boron or one of its compounds (JP 60-77943 / 85 or JP 60-27105 / 85).
  • Patent JP 59-219404 describes the reduction of rare earth oxides with Ca or CaH2 at 1120 ° C.
  • Patent JP 60 77943 describes the reduction of rare earth oxides or halides by Ca in the presence of Fe and B.
  • the latter can be added in the form of halides, oxide or ferro-boron; Fe can be added in powder form or can come partly from the crucible in which the reduction is carried out.
  • the amount of Ca is 2 to 4 times the stoichiometry and the heating of the reaction medium is carried out under inert gas, with stirring, in the presence of CaCl2 (flux) up to a temperature between 900 and 1200 ° C. The product is then poured.
  • Patent application EP 170372 describes the reduction of rare earth oxides by Ca.
  • the oxides are dissolved in a chloride mixture (CaCl2 + NaCl), into which the calcium powder is introduced as well as elements such as Fe, Zn for lower the melting point of the alloy obtained.
  • the reactor is heated to 675 ° C-700 ° C, the mixture is stirred and CaCl2 is added regularly to maintain its concentration at 70%.
  • Patent application EP 170373 describes, as before, a process for the reduction of rare earth oxide with Ca, but said calcium is generated in the reaction medium by the addition of sodium which reacts with Calcium chloride.
  • the heating temperature is between 650 and 800 ° C and the reaction mixture is stirred.
  • Patent application FR 2 548 687 with its certificate of addition FR 2 551 769 describe the reduction of rare earth halides, to which the elements involved in the manufacture of the magnet can be added, by an alkali metal (Na, K , Li) or alkaline earth (Ca, Mg) in excess, in the presence of a flux (CaCl2 and / or CaF2) of the slag obtained.
  • the heating temperature is between 800 ° C and 1100 ° C and the reaction takes place under an inert atmosphere.
  • the rare earths being very aggressive and having a high reducing power, the choice of a reactor which is refractory and inert is difficult. Metals are generally attacked by rare earths and can thus pollute the alloy. Only tantalum and boron nitride resist well, but they are expensive and difficult to use, making their industrial use problematic and unrealistic.
  • the usual ceramics such as those based on alumina, magnesia, silica, on the one hand tend to be either reduced by the reducing metal used, or by the rare earths produced, particularly by Neodymium, and thus to be source of pollution of the alloy, on the other hand to be attacked by the slag produced, making problematic the behavior of the reactor over time; the separation between the slag and the alloy can then be ill-defined and be a source of inclusions in the alloy.
  • carbon-containing ceramics can cause rare earth carburization. Products like boron nitride could be used, but given their cost, their industrial use is compromised. Only refractories of the same kind as the slag produced are likely not to pollute the alloy provided however, to limit the duration and the temperature of the operation so that the flux introduced into the reaction medium does not have the possibility of attacking the refractory.
  • the object of the invention is therefore to obtain a master alloy mainly intended for the manufacture of permanent magnets containing one or more rare earths (including Yttrium), Fe being able to be partially substituted or added by another transition element such as cobalt, nickel, tin, zinc ... and possibly other elements such as boron, which is of high purity, without inclusion or pollution by reagents or other products present, and under industrial and economic conditions (high yield close to or greater than 95%, low reactivity, high productivity).
  • rare earths including Yttrium
  • Fe being able to be partially substituted or added by another transition element such as cobalt, nickel, tin, zinc ... and possibly other elements such as boron
  • Another object is to obtain this alloy by metallothermic reduction from common rare earth compounds.
  • a positive degree of oxidation such as oxides and / or halides
  • any alkali or alkaline-earth metal for example sodium, calcium, magnesium.
  • Another object is to obtain alloy ingots of very varied sizes ranging from a few kgs to more than a ton.
  • Another object is to obtain alloy ingots, without casting (although the use of casting is also possible), having after cooling a good homogeneity of composition and very smooth surface states so that they are marketable without washing or other reflow or purification treatments, only a light pickling is sufficient.
  • the object is to obtain a very good alloy-slag separation with easy recovery of one and the other, the alloy having no slag inclusions and vice versa.
  • Another object is the development of a simple and rapid process, in particular without the use of a special atmosphere, for example vacuum and / or inert gas, and without the use of a flux of slag flux.
  • a special atmosphere for example vacuum and / or inert gas
  • Another object is the possibility of recycling the slag generated after elimination of the soluble elements which are themselves recoverable.
  • the invention is an industrial process for obtaining (preferably without casting) ingots of high purity master alloy, mainly for their use for the manufacture of permanent magnets, based on rare earths, containing at least one or more transition metals such as preferably but not limited to iron, cobalt, nickel, and possibly other elements such as boron, silicon, aluminum, in general containing any element effective for improving the metallurgical qualities and / or magnetic (curie point, coercive field, residual induction) of the alloys obtained. It is a process operating by metallothermic reduction of a rare earth compound (including Yttrium) or a mixture of these compounds, using a reducing agent such as alkali or alkaline earth metals. including magnesium, or their reducing compounds such as hydrides.
  • a rare earth compound including Yttrium
  • a reducing agent such as alkali or alkaline earth metals. including magnesium, or their reducing compounds such as hydrides.
  • the process according to the invention differs from the process described in document FR-A-2 548 687 in that in this document a starting reaction mixture is prepared containing a neodymium halide, a reducing metal, another metal M and optionally a calcium halide, said mixture is introduced into a crucible which may be a refractory steel, and the reaction is carried out at a temperature between 800 and 1100 ° C.
  • the crucible is then allowed to cool in the open air or by any other known means, the charge of the crucible once solidified and sufficiently cooled is removed from the mold, the alloy ingot is then separated from its slag.
  • Rare earth compounds as well as compounds of transition metals or other additives are preferably used in their anhydrous form.
  • the reaction mixture should preferably be dry and may be in the form of a powder or pellets.
  • a drying operation of the various compounds may be necessary before making the mixture, so that its water content does not exceed 0.5%, but in general these products are not very hygroscopic and have a humidity of less than 0.1%. .
  • transition metals in the form of compounds which can be reduced in sufficient quantity is necessary to contribute to the thermal balance of the reaction, in particular to the melting of the reaction charge.
  • anions linked to the rare earths and those linked to the transition metal constituting the alloy be different so as to obtain, after reduction, a low-melting slag.
  • an oxide or a fluoride of rare earth and a chloride of transition metal can be used.
  • the addition of a slag flux if it can be useful in certain cases, is generally not necessary.
  • ferric chloride is advantageous because, in addition to the fact that it is a product readily available on the market in industrial quantity whereas, for example, fluoride is not found in industrial quantity and its price excludes it. use, it has the particularity of giving a strongly exothermic reaction during its reduction.
  • the quantity of the various products of the reaction mixture is mainly regulated by the composition of the alloy to be obtained.
  • the respective quantities of rare earths and of transition metal can also be chosen preferentially so that an alloy with a low melting point is obtained at the end of the reaction, for example in the vicinity of its eutectic composition (in particular the case of Fe and Nd), the possible addition element being added to this composition.
  • Another essential criterion for choosing the quantity of the compound (s) of the transition metal (s) whose presence is necessary is based on the quantity of calories released by the reduction of the said compounds which must be sufficient to cause the melting of the entire reaction charge, including the metal of transition possibly added in part in elementary form, and to bring it to a sufficiently high temperature favoring the alloy-slag settling
  • the slag generated during the reduction of the compound of the transition metal also serves as flux for the slag resulting from the reduction of the composed of rare earths.
  • This process is applicable in particular to the production of ingots of high purity mother alloy based on neodymium and iron, which may also contain praseodymium and / or dysprosium in addition or in partial substitution of neodymium, and optionally boron.
  • This master alloy can be used, after subsequent adjustment of the compositions, to the production of permanent magnets containing approximately 34% Nd, 65% Fe, 1% B.
  • the proportion of the compound of the transition metal (s) introduced into the starting reaction mixture in such a way that the ratio of the weight of the said transition metal (s) introduced in the form of compound, to the weight of the whole rare earth plus total transition metal is between 5 and 50% and preferably between 10 and 20%.
  • These value ranges are particularly recommended when the transition metal is iron and when it is used in the form of chloride, for example ferric chloride.
  • the final metal or transition metal content of the alloy can be obtained by introducing it or them into the starting reaction mixture partly in the form of compounds in the ranges of contents mentioned above and partly in elementary form (for example ferric chloride plus Fe and / or more cobalt), so that the exothermicity released by the various reduction reactions is such that the alloy obtained and the slag generated melt and have a sufficiently low viscosity to obtain good decantation of alloy-slag.
  • an element such as boron in elementary form or as compounds to the reaction mixture.
  • the reducing agent is introduced in slight excess relative to the total amount necessary for the reduction of all of the compounds to be reduced, possibly including boron compounds or other elements. This excess is generally between 0 and 20% and preferably between 0 and 10%.
  • a container or crucible of any shape is used, adapted in particular to the shape which it is desired to give to the alloy ingot and the slag, to facilitate, for example, demolding, subsequent machining or all other operations.
  • the material of the crucible is of any kind and must withstand the mechanical and thermal stresses undergone during filling, metallothermic reaction, cooling or casting, demolding and / or cleaning carried out between each metallothermic preparation. It is preferable to choose a metal crucible, in particular steel.
  • the latter is of the same nature as the slag generated by the reduction of the rare earth compound, for example CaO, CaF2, MgO, MgF2.
  • the rare earth compound for example CaO, CaF2, MgO, MgF2.
  • Being a by-product of the reaction it will thus be easily recyclable, available in sufficient quantity and will not be attacked by the molten alloy. Its thickness varies from 0.5 cm to 5 cm depending on the size of the ingot produced. It can either be made by introducing a male shape into the crucible, thus delimiting an annular space in which the pot lining powder will be introduced.
  • the reaction mixture sufficiently homogenized, is introduced inside the metal or brazed crucible. It can be packed in order to increase the quantity introduced; a pot cap of a few centimeters thick is made above the upper surface of the mixture after having optionally degassed the reaction mixture.
  • the full container can be left open, but or can close it using a lid fixed to the crucible, for example by bolting in order to avoid possible projections during the reaction.
  • the reaction is then started, by priming by a known means such as a priming charge, electric current, or by heating, by introducing the container into an oven of any type (resistance, fuel, induction, solar ...) brought to a moderate temperature of at least 150 ° C and preferably between 150 ° C and 300 ° C, which it is not necessary to exceed.
  • the heating time varies from 0.5 to 5 h.
  • the reaction starts by itself and the heat released "in situ" is such that the products of the reaction melt; the temperature reached is generally at least 1300 ° C.
  • the alloy precipitates at the bottom of the pot lining crucible without attacking it and the low-melting slag floats by partially attacking said pot lining.
  • the reaction is rapid, of the order of a few minutes.
  • the alloy does not have the possibility of undergoing significant oxidation being protected by the slag generated; this generally allows the operation to be carried out at atmospheric pressure and in air.
  • it is possible to operate under reduced pressure, or under an inert or reducing atmosphere at normal pressure or above atmospheric pressure.
  • the container is allowed to cool in the open air or by any other accelerated cooling means (water in the double jacket, air flow, surface water, quenching, etc.).
  • any other accelerated cooling means water in the double jacket, air flow, surface water, quenching, etc.
  • This process makes it possible to obtain ingots of alloy without inclusion, of high purity, and of homogeneous composition.
  • the yields are generally close to or greater than 95% without stirring during the reaction or long-term heating at high temperature being necessary.
  • this process can be carried out without casting.
  • the process according to the invention can advantageously be supplemented by recovery of the pot lining with a high melting point contained in the slag obtained.
  • said slag contains a soluble halide and an insoluble fluoride or refractory oxide, it can be treated with water (after possible grinding), separate the insoluble part which can then be dried and recycled, after grinding and particle size adjustment , to be used for the ramming of the crucible.
  • the rare earth compounds are oxides or fluorides
  • the transition metal compounds are chlorides and when the reducing agent is Ca or Mg; the slag is then treated with water, the calcium and / or magnesium chlorides are separated in the aqueous phase and the calcium and / or magnesium oxides or fluorides in the solid phase which can then be recycled to make the pot lining. the following operation, or for any other use or storage.
  • a transition metal compound can be introduced into the starting reaction mixture, giving after reduction a volatile metal which, in said variant, can be removed from the mother alloy obtained by distillation.
  • the reaction mixture can for example contain the rare earth compound, a Zn compound, such as its chloride, another transition metal in elementary form such as Fe and the reducing agent.
  • the alloy then being obtained according to the process in accordance with the invention, the variant consists in taking up the mother alloy, in melting it under vacuum or in a controlled atmosphere and in distilling the Zn to obtain the rare earth metal.
  • a mild steel crucible of frustoconical shape of about 250 l is used, into which a male shape is introduced so as to delimit an annular space of constant thickness.
  • the crucible is fixed on a vibrating table.
  • a CaF2 powder is dried at 150 ° C for 24 h, then introduced into the annular space and simultaneously compacted using the vibrating table. After extraction of the male form, the brazed crucible is ready to receive the reaction mixture.
  • a layer of pot lining forming a cap is placed over the mixture, and the crucible is closed by a steel cover bolted to the crucible.
  • a thermocouple is placed in contact with the outside wall of the crucible.
  • the crucible is placed in an oven. It is gradually heated to a temperature of 150 ° C. over 0.5 h, a level is maintained at this temperature until the start of the reaction observed on the thermocouple; it occurs after 2:45. The reaction lasts a few minutes. The heating is stopped, the crucible removed from the oven and cooled in the open air.
  • the crucible is turned over and emptied of its solid content: the pot lining remains in the form of powder and the ingot of mother alloy is easily separated from the slag. The ingot is then brushed and cleaned before taking samples. The ingot obtained weighs 93.4 kg and its analysis is as follows (% by weight):
  • the ingot obtained weighs 94.4 kg and its composition is as follows (% by weight): The yield of rare earth is 99.4%.
  • part of the Fe in metal form of the previous example is replaced by ferro-boron with a composition of the mixture which has become the following:
  • We have a ratio: Fe (in the form of a compound) / Rare earths + total Fe 13.7%
  • the ingot obtained weighs 1214 g and its composition is as follows: The yield of rare earths is 94.7%.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
EP87420319A 1986-11-27 1987-11-26 Procédé d'élaboration par métallothermie d'alliages purs à base de terres rares et de métaux de transition Expired - Lifetime EP0273835B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8616948 1986-11-27
FR8616948A FR2607520B1 (fr) 1986-11-27 1986-11-27 Procede d'elaboration par metallothermie d'alliages purs a base de terres rares et de metaux de transition

Publications (2)

Publication Number Publication Date
EP0273835A1 EP0273835A1 (fr) 1988-07-06
EP0273835B1 true EP0273835B1 (fr) 1991-06-19

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US (1) US4767455A (enrdf_load_stackoverflow)
EP (1) EP0273835B1 (enrdf_load_stackoverflow)
JP (1) JPS63153230A (enrdf_load_stackoverflow)
DE (1) DE3770932D1 (enrdf_load_stackoverflow)
FR (1) FR2607520B1 (enrdf_load_stackoverflow)

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JP5378644B2 (ja) * 2006-09-29 2013-12-25 Ｄｏｗａホールディングス株式会社 窒化物蛍光体または酸窒化物蛍光体の製造方法
US8821650B2 (en) * 2009-08-04 2014-09-02 The Boeing Company Mechanical improvement of rare earth permanent magnets
RU2419655C1 (ru) * 2009-10-07 2011-05-27 Государственное образовательное учреждение высшего профессионального образования "Алтайский государственный технический университет им. И.И. Ползунова" (АлтГТУ) Способ получения легированного сплава железа из отходов производства
RU2419654C1 (ru) * 2009-10-12 2011-05-27 Государственное образовательное учреждение высшего профессионального образования "Алтайский государственный технический университет им. И.И. Ползунова" (АлтГТУ) Способ получения легированного сплава железа из отходов производства
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US11788171B2 (en) 2020-03-19 2023-10-17 Battelle Energy Alliance, Llc Methods of recovering an elemental rare earth metal, and methods of forming a rare earth metal
CN114703384B (zh) * 2022-03-31 2023-07-25 江苏南方永磁科技有限公司 一种用于稀土回收的清渣剂材料及其制备和使用方法
CN115418704B (zh) * 2022-08-30 2023-10-03 广东省科学院资源利用与稀土开发研究所 一种稀土铁硼永磁单晶的助熔剂生长方法

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Publication number Publication date
FR2607520B1 (fr) 1992-06-19
JPH0364574B2 (enrdf_load_stackoverflow) 1991-10-07
EP0273835A1 (fr) 1988-07-06
JPS63153230A (ja) 1988-06-25
DE3770932D1 (de) 1991-07-25
US4767455A (en) 1988-08-30
FR2607520A1 (fr) 1988-06-03

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