EP0170372A1 - Metallothermische Reduktion seltener Erdoxide mittels Kalzium - Google Patents

Metallothermische Reduktion seltener Erdoxide mittels Kalzium Download PDF

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Publication number
EP0170372A1
EP0170372A1 EP85304046A EP85304046A EP0170372A1 EP 0170372 A1 EP0170372 A1 EP 0170372A1 EP 85304046 A EP85304046 A EP 85304046A EP 85304046 A EP85304046 A EP 85304046A EP 0170372 A1 EP0170372 A1 EP 0170372A1
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EP
European Patent Office
Prior art keywords
rare earth
bath
oxide
metal
metallothermic
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EP85304046A
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English (en)
French (fr)
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EP0170372B1 (de
Inventor
Ram Autar Sharma
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Motors Liquidation Co
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General Motors Corp
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Priority to AT85304046T priority Critical patent/ATE36560T1/de
Publication of EP0170372A1 publication Critical patent/EP0170372A1/de
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Publication of EP0170372B1 publication Critical patent/EP0170372B1/de
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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
    • 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
    • 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

Definitions

  • This invention relates to a novel metallothermic process for the direct reduction of rare-earth oxide, particularly neodymium oxide, to rare earth metal.
  • the method has particular application to low cost production of neodymium metal for use in neodymium-iron-boron magnets.
  • Sources of the rare earth (RE) elements are bastnaesite and monazite ores. Mixtures of the rare earths can be extracted from the ores by several well known beneficiating techniques. The rare earths can then be separated from one another by such conventional processes as elution and liquid-liquid extraction.
  • the electrolytic processes include (1) decomposition of anhydrous rare earth chlorides dissolved in molten alkali or alkaline earth salts, and (2) decomposition of rare earth oxides dissolved in molten rare earth fluoride salts.
  • Electrolytic processes include the use of expensive electrodes which are eventually consumed, the use of anhydrous chloride or fluoride salts to prevent the formation of undesirable RE-oxy salts (NdOCl, e.g.), high temperature cell operation (generally greater than 1000°C), low current efficiences resulting in high power costs, and low yield of metal from the salt (40% or less of the metal can be recovered).
  • RE-oxy salts NaOCl
  • high temperature cell operation generally greater than 1000°C
  • low current efficiences resulting in high power costs and low yield of metal from the salt (40% or less of the metal can be recovered.
  • the RE-chloride reduction process releases corrosive chlorine gas while the fluoride process requires careful control of a temperature gradient in the electrolytic salt cell to cause solidification of rare earth metal nodules.
  • An advantage of electrolytic processes is that they can be made to run continuously if provision is made to tap the reduced metal and to refortify the salt bath.
  • the metallothermic (non-electrolytic) processes include (1) reduction of RE-fluorides with calcium metal powder (the calciothermic process), and (2) reduction-diffusion of RE-oxide with calcium hydride (CaH 2 ) or calcium metal (Ca).
  • both are batch processes, they must be conducted in a non-oxidizing atmosphere, they'are energy intensive and the product in the case of reduction-diffusion is a powder which must be hydrated to purify it before use. Both processes involve many steps.
  • One advantage of the metallothermic reduction processes is that the yield of metal from the oxide or fluoride is generally better than ninety percent.
  • a reaction vessel is provided which can be heated to desired temperatures by electrical resistance heaters or some other heating means.
  • the vessel body is preferably made of a metal or refractory material that is either substantially inert or innocuous to the reaction constituents.
  • a predetermined amount of RE-oxide is charged into the reaction vessel containing a salt mixture of about 70 weight percent calcium chloride or greater and about 5 to 30 weight percent sodium chloride (NaCl).
  • the salt serves as a medium for the reduction reaction.
  • a stoichiometric excess of calcium metal, based on the amount of rare earth oxide, is added. It may be advantageous to add an amount of another metal such as iron or zinc to form a eutectic alloy with the reduced rare earth metal to enable the reaction to be carried out at lower temperatures and to obtain the RE metal product in a liquid state.
  • the vessel is heated to a temperature above the melting point of the constituents (about 675 0 C).
  • the molten constituents are rapidly stirred in the vessel to keep them in contact with one another as the reaction progresses.
  • the bath is replenished with calcium chloride (CaCl2) as necessary to maintain a weight percent of 70% of the combined weights of CaCl 2 and NaCl. While the reaction runs at CaCl 2 concentrations lower than 70%, the yield falls off rapidly.
  • the reduced metal has a density of about 7 grams/cc while that of the salt bath is about 1.9 grams/cc.
  • the reduced metal forms a clean layer at the bottom of the reaction vessel. This layer may be tapped while molten or separated from the salt layer after it solidifies.
  • the method of the invention provides many advantages over prior art methods. It is carried out at a relatively low temperature of about 700°C, particularly where the rare earth metal is recovered as a zinc or iron eutectic alloy. It uses relatively inexpensive RE-oxide, CaCl2, NaCl and Ca metal reactants. It does not require pretransformation of RE-oxide to chloride or fluoride, nor the use of expensive pure Ca or CaH 2 reducing agent. Energy consumption is low because the method is not electrolytic and it is preferably carried out at atmospheric pressure at temperatures at about 700°C. The method can be practiced as either a batch or a continuous process, and the by-products of CaCl 2 , NaCl and calcium oxide (CaO) are easily disposed of. Moreover, the rare earth metals may be alloyed with additional iron in the reaction vessel if they are made as a RE-Fe eutectic alloy or may be alloyed later for use in RE-Fe magnets without further expensive purification treatments.
  • the rare earth metals include elements 57 to 71 of the periodic table (lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium) and atomic number 39, yttrium.
  • the oxides of the rare earths are generally coloured powders produced in the metals separation process.
  • the term "light rare earth” refers to the elements lanthanum (La), cerium (Ce), praseodymium (Pr) and neodymium (Nd).
  • the RE-oxides can generally be used as received from the separator but may be calcined to remove excess absorbed moisture or carbon dioxide.
  • the RE-oxides were oven-dried for about two hours at 1000°C prior to use.
  • the CaCl 2 and NaCl for the salt baths were reagent grade and dried for about two hours at 500°C prior to use.
  • both RE-oxides and R E -oxychlorides are readily reduced by calcium metal.
  • the formation of RE-oxychlorides is advantageous because they float on molten layers of reduced RE metals.
  • RE-oxides on the other hand, have densities close to the reduced RE metals so they may be retained as contaminants in the molten layers of reduced RE metals, and may make the RE metals unsuited for use in magnets.
  • the RE metals reduced by the method according to the present invention have been substantially oxide-free.
  • Unalloyed N d metal has a melting temperature of about 1025°C.
  • the other rare earth metals also have high melting points. If one wanted to run the subject reaction at such temperatures, it would be possible to do so and obtain pure metal at,high yields.
  • iron forms a low melting eutectic alloy with neodymium (11.5 weight percent Fe; m.p. about 640°C) as does zinc (11.9 weight percent Zn, m.p. about 630 o C).
  • a Nd-Fe eutectic alloy may be directly alloyed with additional iron and boron to make magnets having the optimum Nd 2 Fe 14 B magnetic phase described in the aforementioned European patent applications.
  • a metal with a boiling point much lower than the boiling point of the recovered rare earth can be added to the reaction vessel.
  • the low-melting metal can then be readily separated from the rare earth metal by simple distillation.
  • Yttria-lined alumina and boron nitride are non-reactive, refractory materials generally acceptable. It is also possible to use a refractory liner made of a substantially inert metal such as tantalum or a consumable but innocuous metal such as iron. An iron liner could be used to contain reduced RE metal and then be alloyed with the RE for use in magnets.
  • a new method has been discovered of using calcium metal to reduce rare earth oxides.
  • the method entails bringing together molten calcium and RE-oxide to cause the reaction RE n O m + m Ca -> n RE + m CaO.
  • the reaction vessel is pressurized, it is desirable to keep the temperature at about 910°C to avoid the excessive loss of Na formed by the reaction of Ca with NaCl. It is preferred to run the reactions at atmospheric pressure.
  • the most preferred range of operating temperatures is between about 650°C and 750°C. At such temperatures wear on the reaction vessel is not excessive.
  • This temperature range is suitable for reducing Nd 2 0 3 to Nd metal because the Nd-Fe and Nd-Zn eutectic melting-point temperatures are below 700°C. Moreover, at about 700°C the solublitiy of Ca metal in the salt bath is about 1.3 molecular percent. This is sufficient to rapidly reduce RE-oxide to RE metal.
  • the reaction temperature must be above the melting point of the reduced RE metal or the melting point of the reduced RE metal alloyed or co-reduced with another metal.
  • These relatively dense RE metals and alloys collect at the bottom of the reaction vessel when allowed to settle. There they can be tapped while molten or removed after solidification.
  • Table I shows the molecular weight (m.w.), density ( p ) at 25°C, melting point (m.p.) and boiling point (b.p.) for elements and compounds used in the present invention.
  • FIG 1 shows an apparatus suitable for the practice of the invention in which the experiments set out in the several examples were conducted.
  • the furnace was heated by means of three tubular, electric, clamshell heating elements 8, 10 and 12 having an inside diameter of 13.3 cm and a total length of 45.7 cm.
  • the side and bottom of the furnace well were surrounded with refractory insulation 14.
  • Thermocouples 15 were mounted on an outer wall 16 of furnace well 20 at various locations along its length.
  • One of the centrally located thermocouples was used in conjunction with a proportional band temperature controller (not shown) to automatically control centre clamshell heater 10.
  • the other three thermocouples were monitored with a digital temperature readout system and top and bottom clamshell heaters 8 and 12 were manually controlled with transformers to maintain a fairly uniform temperature throughout the furnace.
  • reaction vessel 22 was carried out in a reaction vessel 22 retained in a stainless steel crucible 18 having a 10.2 cm outer diameter, 12.7 cm deep and 0.15 cm thick retained in stainless steel furnace well 20.
  • Reaction vessel 22 was made of tantalum metal unless otherwise noted in the examples.
  • a tantalum stirrer 24 was used to agitate the melt during the reduction process. It had a shaft 48.32 cm long and a welded blade 26.
  • the stirrer was powered by a 100 W variable speed motor 28 capable of operating at speeds up to 700 revolutions per minute.
  • the motor was mounted on a bracket 30 so that the depth of stirrer blade 26--in reaction vessel 22 could be adjusted.
  • the shaft was journalled in a bushing 32 carried in an annular support bracket 34. The bracket is retained by collar 35 to which furnace well 20 is fastened by bolts 37.
  • Chill water coils 36 were located near the top of well 20 to promote condensation and prevent escape of volatile reaction constituents.
  • Cone-shaped stainless steel baffles 38 were used to reflux Na vapors. Reflux products drop through tube 40 on bottom baffle 42.
  • Figure 2 is an idealized flow chart for the reduction of Nd 2 0 3 to Nd metal in accordance with this invention.
  • the Nd 2 0 3 is added to the reaction vessel along with calcium chloride and sodium chloride in suitable proportions. Calcium metal and enough of a eutectic forming metal such as iron or zinc to form a near eutectic Nd alloy are added.
  • the reaction is run, with rapid stirring at about 300-700 revolutions per minute at a temperature of about 700°C for at least one hour.
  • a blanket of an inert gas such as helium is maintained over the reaction vessel.
  • Nd 2 0 3 After the Nd 2 0 3 has been reduced, stirring is continued at a lower speed of 100 revolutions per minute for one hour and then stirring is stopped to allow the various liquids in the vessel to stratify.
  • the reduced N d eutectic alloy collects at the bottom because it has -. the highest density.
  • the remaining salts and any unreacted Ca collect above the Nd alloy and can be readily broken away after the vessel has cooled and the constituents have solidified.
  • Nd-Fe alloys so produced can be alloyed with additional elements to produce permanent magnet compositions. These magnet alloys may be processed by melt-spinning or they can be ground and processed by powder metallurgy to make magnets.
  • the furnace temperature was lowered to about 720 0 C.
  • 150 grams of NaCl and 350 grams of CaCl 2 were added to create a salt bath of 70 weight percent CaCl 2 .
  • 234 grams (0.7 moles) Nd 2 0 3 were added.
  • 104 grams of Ca (2.6 moles) metal were added to the crucible and it was stirred at a rate of 300 revolutions per minute for about two hours and then for another hour at a stirring rate of 60 revolutions per minute.
  • the crucible was removed from the furnace and cooled on the floor of the drybox.
  • the furnace temperature was lowered to about 720°C. 300 grams of NaCl and 700 grams of CaCl 2 were added to create a salt bath of 70 weight percent CaCl 2 . 117 grams (0.35 moles) of Nd 2 0 3 were added. 46 grams (1.15 moles) of Ca metal and 10.8 grams (0.47 moles) of Na were added to the crucible and they were stirred at a rate of 300 revolutions per minute for about 135 minutes. At this point an additional 117 grams (0.35 moles) of Nd203. 46 grams (1.15 moles) of Ca metal and 10.8 grams (0.47 moles) of Na were added. The reactants were stirred for another 114 minutes at 300 rpm and then for another hour at a stirring rate of 60 rpm. The reaction vessel was removed from the furnace and cooled on the floor of the drybox. A layer of unreacted Ca-Na alloy formed on top of the salt layer.
  • Nd-Fe alloy 594 grams of 97% purity Nd-Fe alloy were recovered. Such alloy could be combined directly as recovered with additional iron and boron to make the ideal Nd-Fe-B alloy for permanent magnet manufacture. 180 grams of Nd metal of purity greater than 99% was recovered as Nd-Fe alloy. This example shows that a calcium and sodium melt is capable of reducing a rare earth oxide in a CaCl 2 -NaCl flux bath.
  • Table II sets out the amounts of various constituents used in the metallothermic reduction of about 234 grams Nd 2 0 3 with Ca metal using the process set out in Example II except that the reactants were stirred for four hours at 300 revolutions per minute followed by an additional hour of stirring at 60 rpm.
  • FIG. 3 is a plot of Nd metal yield from Nd 2 0 3 as a function of the weight percent CaCl 2 in a two component NaCl-CaCl 2 starting salt bath with a Ca metal reductant. Referring to Table II and Figure 3, it has been found that, to obtain high yields, it is necessary to maintain the amount of CaC12 in the salt bath above about 70 weight percent. It is also desirable to have a salt to RE-oxide volume ratio of at least 2:1 to provide adequate flux for the dispersion of RE-oxide. It has been observed that, as the volume ratio of the salt bath to RE-oxide increases, the rate of stirring may be
  • the CaCl 2 -containing bath is a significant feature of this invention.
  • the resultant alloy was analyzed and was found to be of greater than 99% purity with 0.4% aluminium, 0.1% silicon, 0.01% calcium and traces of zinc, magnesium and iron contamination.
  • the Nd metal so produced was melted in a vacuum furnace with electrolytic iron and ferroboron to produce an alloy having the nominal composition Nd 0.15 B 0.05 Fe 0.80 .
  • the alloy was melt-spun, as described in European patent application No.0108474 cited above, to produce very finely crystalline ribbon with an as-quenched coercivity of about 10 megaGaussOersteds.
  • a new, efficient and less costly method of reducing rare earth oxides to rare earth metals has been developed. It entails the formation of a suitable, molten, caCl 2 -based bath in which rare earth oxide is stirred with an amount of calcium metal sufficient to reduce it. When stirring is stopped, the components settle into discrete layers which can be broken apart when they cool and solidify.
  • the reduced liquid rare earth metal can be tapped from the bottom of the reaction vessel. After the RE metal is tapped, the bath can be refortified to run another batch, making the process a substantially continuous one.

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  • Manufacturing & Machinery (AREA)
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  • Metallurgy (AREA)
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  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Electrolytic Production Of Metals (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
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EP85304046A 1984-07-03 1985-06-07 Metallothermische Reduktion seltener Erdoxide mittels Kalzium Expired EP0170372B1 (de)

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AT85304046T ATE36560T1 (de) 1984-07-03 1985-06-07 Metallothermische reduktion seltener erdoxide mittels kalzium.

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US62773684A 1984-07-03 1984-07-03
US627736 1984-07-03

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EP0170372A1 true EP0170372A1 (de) 1986-02-05
EP0170372B1 EP0170372B1 (de) 1988-08-17

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EP (1) EP0170372B1 (de)
JP (1) JPS6130639A (de)
KR (1) KR910001581B1 (de)
AT (1) ATE36560T1 (de)
AU (1) AU575965B2 (de)
BR (1) BR8503140A (de)
DE (1) DE3564451D1 (de)
ES (1) ES8702508A1 (de)
MX (1) MX173880B (de)
ZA (1) ZA854474B (de)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238185A1 (de) * 1986-03-18 1987-09-23 General Motors Corporation Metallothermische Reduktion der Chloride der seltenen Erden
EP0254251A3 (en) * 1986-07-21 1989-01-25 Hitachi Metals, Ltd. Method of producing neodymium-iron-boron permanent magnet
EP0265413A3 (en) * 1986-08-19 1989-03-29 Treibacher Chemische Werke Aktiengesellschaft Process for the manufacture of rare-earth metals and of alloys containing rare-earth metals
EP0319770A1 (de) * 1987-11-24 1989-06-14 Mitsubishi Materials Corporation Verfahren zum Rückgewinnen von Samarium und Europium aus verbrauchten Bädern für die Herstellung von Mischmetall durch Salzbadelektrolyse
EP0343378A1 (de) * 1988-05-24 1989-11-29 Leybold Aktiengesellschaft Verfahren zum Herstellen von Metallen aus der Gruppe Titan, Zirkonium, Chrom, Samarium und Neodym aus ihren Oxiden
EP0364089A1 (de) * 1988-10-11 1990-04-18 General Motors Corporation Verfahren zum Dekalzifieren von Seltenerdmetallen, erhalten durch ein Reduktions-Diffusionsverfahren
WO2004007808A1 (ja) * 2002-07-16 2004-01-22 Cabot Supermetals K.K. ニオブ粉末またはタンタル粉末の製造方法および製造装置
US20130056193A1 (en) * 2010-01-12 2013-03-07 Sylvan Source, Inc. Heat transfer interface
CN103436718A (zh) * 2013-08-16 2013-12-11 宁夏东方钽业股份有限公司 一种高纯金属镧的制取方法
CN111139366A (zh) * 2020-01-17 2020-05-12 蔡天财 一种钠冷快堆中核纯级冷却材料制备提纯方法及其设备

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4578242A (en) * 1984-07-03 1986-03-25 General Motors Corporation Metallothermic reduction of rare earth oxides
KR100373109B1 (ko) * 1999-09-30 2003-02-25 해 남 현 토양의 치환성 칼리 침출방법 및 이를 이용하여 침출된 토양 치환성 칼리의 정량방법
RU2405045C2 (ru) * 2008-05-12 2010-11-27 Анатолий Евгеньевич Волков Способ и устройство автоклавного производства химически активных металлов
CA3101795C (en) 2018-05-30 2023-10-10 Hela Novel Metals Llc Methods for the production of fine metal powders from metal compounds
KR102153737B1 (ko) * 2019-12-12 2020-09-09 한국지질자원연구원 철-희토류계 영구자석으로부터 선택염화법에 의한 희토류 원소의 회수 방법
KR20260001320A (ko) 2024-06-27 2026-01-05 주식회사 케이에스엠테크놀로지 목적금속의 순도향상 방법

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GB190923215A (en) * 1909-10-11 1910-09-29 Hans Kuzel Process for the Production of Zirconium and other Rare Metals.
US2950962A (en) * 1957-03-28 1960-08-30 Carlson Oscar Norman Reduction of fluoride to metal
GB1040468A (en) * 1964-10-26 1966-08-24 Dow Chemical Co Preparation of rare earth metal, yttrium, or scandium
FR2396802A1 (fr) * 1977-07-05 1979-02-02 Johnson Matthey Co Ltd Procede de fabrication d'yttrium et d'alliages d'yttrium
EP0108474A2 (de) * 1982-09-03 1984-05-16 General Motors Corporation RE-TM-B Legierungen, deren Herstellung und permanent Magnete die solche Legierungen enthalten

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SU1027232A1 (ru) * 1982-01-15 1983-07-07 Научно-исследовательский институт металлургии Способ получени лигатуры
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GB190923215A (en) * 1909-10-11 1910-09-29 Hans Kuzel Process for the Production of Zirconium and other Rare Metals.
US2950962A (en) * 1957-03-28 1960-08-30 Carlson Oscar Norman Reduction of fluoride to metal
GB1040468A (en) * 1964-10-26 1966-08-24 Dow Chemical Co Preparation of rare earth metal, yttrium, or scandium
FR2396802A1 (fr) * 1977-07-05 1979-02-02 Johnson Matthey Co Ltd Procede de fabrication d'yttrium et d'alliages d'yttrium
EP0108474A2 (de) * 1982-09-03 1984-05-16 General Motors Corporation RE-TM-B Legierungen, deren Herstellung und permanent Magnete die solche Legierungen enthalten

Non-Patent Citations (1)

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Title
CHEMICAL ABSTRACTS, vol. 99, 1983, abstract no. 126355g, Columbus, Ohio, US; & SU-A-1 027 232 (SCIENTIFIC-RESEARCH INSTITUTE OF METALLURGY) 07-07-1983 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0238185A1 (de) * 1986-03-18 1987-09-23 General Motors Corporation Metallothermische Reduktion der Chloride der seltenen Erden
AU584494B2 (en) * 1986-03-18 1989-05-25 General Motors Corporation Metallothermic reduction of rare earth chlorides
EP0254251A3 (en) * 1986-07-21 1989-01-25 Hitachi Metals, Ltd. Method of producing neodymium-iron-boron permanent magnet
EP0265413A3 (en) * 1986-08-19 1989-03-29 Treibacher Chemische Werke Aktiengesellschaft Process for the manufacture of rare-earth metals and of alloys containing rare-earth metals
EP0319770A1 (de) * 1987-11-24 1989-06-14 Mitsubishi Materials Corporation Verfahren zum Rückgewinnen von Samarium und Europium aus verbrauchten Bädern für die Herstellung von Mischmetall durch Salzbadelektrolyse
EP0343378A1 (de) * 1988-05-24 1989-11-29 Leybold Aktiengesellschaft Verfahren zum Herstellen von Metallen aus der Gruppe Titan, Zirkonium, Chrom, Samarium und Neodym aus ihren Oxiden
EP0364089A1 (de) * 1988-10-11 1990-04-18 General Motors Corporation Verfahren zum Dekalzifieren von Seltenerdmetallen, erhalten durch ein Reduktions-Diffusionsverfahren
WO2004007808A1 (ja) * 2002-07-16 2004-01-22 Cabot Supermetals K.K. ニオブ粉末またはタンタル粉末の製造方法および製造装置
US20130056193A1 (en) * 2010-01-12 2013-03-07 Sylvan Source, Inc. Heat transfer interface
CN103436718A (zh) * 2013-08-16 2013-12-11 宁夏东方钽业股份有限公司 一种高纯金属镧的制取方法
CN111139366A (zh) * 2020-01-17 2020-05-12 蔡天财 一种钠冷快堆中核纯级冷却材料制备提纯方法及其设备
CN111139366B (zh) * 2020-01-17 2024-05-31 鹰潭市宇钠科技中心(有限合伙) 一种钠冷快堆中核纯级冷却材料制备提纯方法及其设备

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AU575965B2 (en) 1988-08-11
JPS6137341B2 (de) 1986-08-23
KR910001581B1 (ko) 1991-03-16
BR8503140A (pt) 1986-03-18
ATE36560T1 (de) 1988-09-15
ES8702508A1 (es) 1987-01-01
JPS6130639A (ja) 1986-02-12
ZA854474B (en) 1986-03-26
ES544799A0 (es) 1987-01-01
AU4448885A (en) 1986-01-09
DE3564451D1 (en) 1988-09-22
MX173880B (es) 1994-04-07
EP0170372B1 (de) 1988-08-17
KR860001203A (ko) 1986-02-24

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