JPS6312947B2

JPS6312947B2 -

Info

Publication number: JPS6312947B2
Application number: JP20773384A
Authority: JP
Inventors: Katsuhisa Ito; Yoshiaki Watanabe; Eiji Nakamura; Masayasu Toyoshima
Original assignee: Sumitomo Light Metal Industries Ltd
Current assignee: Sumitomo Light Metal Industries Ltd
Priority date: 1984-10-03
Filing date: 1984-10-03
Publication date: 1988-03-23
Also published as: JPS6187888A

Description

[Detailed description of the invention]

（技術分野）本発明は、ネオジム−鉄母合金の製造方法並び
にその製造装置に係り、特にネオジム−鉄合金、
なかでも高性能永久磁石用の母合金に適した、ネ
オジム含有量が高く、有害な不純物や介在物の含
有量の低い、ネオジム−鉄合金を連続的に製造す
る方法並びにその装置に関するものである。（発明の背景）最近、高価なサマリウムあるいはコバルトを含
有せず、しかもハードフエライトより磁気特性の
優れた高性能磁石として、希土類−鉄系、希土類
−鉄−ホウ素系の永久磁石が注目されている。な
かでも、ネオジム−鉄−ホウ素系磁石は、最高エ
ネルギー積：（BH）maxが36MGOe以上にもな
り、比重、機械的強度の点からも極めて優れてい
ることが認められている（例えば特開昭59−
46008号公報参照）。このネオジム−鉄系あるいは
ネオジム−鉄−ホウ素系永久磁石は、何れも磁気
特性を劣化させる不純物の少ない原料を必要と
し、特に反応性の大きいネオジム原料について
は、酸素等の不純物の少ないものを製造する工業
的な方法を確立することが必要となつている。ところで、金属ネオジムは、従来、殆ど用途が
なく、その製造方法としては、一般に活性金属、
特にカルシウムによる還元法と溶融塩電解法が知
られているのみで、工業的製造方法は充分に確立
されていない。従つて、上述した如き高性能永久
磁石の原料に適したネオジム−鉄母合金の工業的
製造方法にあつても、充分に確立されていないの
である。かかる状況下、従来の技術水準より考えられる
ネオジム−鉄母合金の製造方法としては、次のよ
うなものを挙げることができるが、それぞれの手
法には各種の問題点が内在しており、何れも、ネ
オジム−鉄母合金を連続的に製造する工業的な乃
至は実用的な手法として充分満足させ得るもので
はないのである。 (a) 金属ネオジムを、まずカルシウム等の活性金
属による還元法あるいは溶融塩電解法によつて
予め製造しておいた後、鉄を添加して、再融解
し、合金化させる方法：この方法にあつては、最初のネオジム製造工
程に問題がある。すなわち、カルシウム等の活
性金属による還元法はバツチ式であり、連続的
な大規模生産には適さないのである。また、溶
融塩電解法では、塩化物電解浴の電解（例え
ば、塩川二朗他、「電気化学」、第35巻、1967
年、第496頁等参照）とフツ化物電解浴に溶解
した酸化物（Nd₂O₃）の電解（E.モーリス他、
「U.S.Bur.Min.、Rep.Invest.」、No.6957、1967
年参照）が知られているが、電解成績並びに操
業方法に問題があり、連続的な大規模生産に適
した方法は確立されていない。 (b) ネオジムの化合物と鉄あるいは鉄の化合物を
混合して、カルシウム等の適当な還元剤によつ
て還元を行ないつつ、合金化させる方法：上述の如く、還元法は一般にバツチ式で実施
されるため、本方法とても連続的な大規模生産
には適さないことは、例外ではない。 (c) 適当な溶融塩からなる電解浴中にネオジムの
化合物と鉄の化合物とを溶解させ、それら化物
の同時電解によつて、非消耗陰極上にネオジム
と鉄の合金として析出させる方法：この方法では、得られる合金組成を一定化さ
せることが難しく、また鉄は溶融塩電解法によ
ることなく、大量且つ安価に別法で製造し得る
ところから、次の(d)の方法より経済性の点にお
いて劣つている。 (d) 鉄自身を陰極として、適当な溶融塩の電解浴
中で、ネオジムの化合物としての酸化ネオジム
（Nd₂O₂）を電解還元して、金属ネオジムを陰
極上に析出させると同時に陰極の鉄と合金化さ
せる、所謂消耗陰極法：本法については、フツ化物電解浴中へ酸化ネ
オジムを供給して電解を行ない、ネオジム−鉄
合金を得ている研究例（E.モーリス他、「U.S.
Bur.Min.、Rep.Invest.」、No.7146、1968年参
照）があつて、前述した(a)〜(c)の方法のような
欠点のない、優れた方法と考えられるが、技術
的には種々な困難が内在している。すなわち、この酸化ネオジムを原料とする電
解方法にあつては、選ばれた電解浴への酸化ネ
オジムの溶解度が２％程度と小さく、且つ本発
明の目的の如く、不純物の少ない金属を得よう
とすると、当該電解浴の温度が低く選択されて
いるために、更にその溶解度が減少する結果、
電解浴への酸化ネオジムの溶解が極めて困難で
あり、原料の供給を連続的に安定して行なうこ
とができないのである。そして、このため、(1)
電解浴への原料供給の不足に基因する、陽極効
果と呼ばれる溶融塩電解に特有の異常現象が頻
発する、(2)未溶解原料が生成合金液滴の合一化
を妨げる、(3)未溶解原料が電解浴の底部に蓄積
して、所謂スラツジを形成し、その結果、介在
物の混入等による生成合金の品位の悪化、原料
の利用率（歩留り）の悪化を招く、(4)陽極効果
の発生による電解成績の悪化を招く、(5)電解の
継続そのものが、時によつては困難になる等の
問題を生じ、これが工業的な連続的操業を困難
ならしめているのである。（発明の概要）ここにおいて、本発明は、かかる事情を背景に
して為されたものであつて、その目的とするとこ
ろは、ネオジム−鉄母合金、なかでも高性能永久
磁石の製造に特に適したネオジム−鉄母合金を、
大規模に且つ連続的に製造し得る方法並びにその
ための装置を提供することにあり、また他の目的
とするところは、ネオジム含有量が高く、有害な
不純物や介在物等の含有量の低いネオジム−鉄母
合金の、信頼性のある経済的な工業的製造方法並
びに装置を提供することにある。すなわち、本発明は、かかる目的を達成するた
めに、鉄陰極及び炭素陽極を用いて、ネオジム化
合物を溶融塩電解浴中において電解還元せしめ、
生成するネオジムを前記鉄陰極上に析出させると
共に、該陰極を構成する鉄と合金化せしめてネオ
ジム−鉄合金を形成させるに際して、前記ネオジ
ム化合物としてフツ化ネオジムを用いると共に、
かかるネオジム化合物を含む前記溶融塩電解浴
が、実質的に35〜76重量％のフツ化ネオジム、20
〜60重量％のフツ化リチウム、40重量％までのフ
ツ化バリウム及び20重量％までのフツ化カルシウ
ムにて構成されるように調整する一方、前記ネオ
ジム−鉄合金を前記鉄陰極上に液体状態で生成せ
しめ、そして該液体状態のネオジム−鉄合金を液
滴として該鉄陰極下方の電解浴中に開口部を有す
る受器内に滴下せしめて液層として溜め、更にこ
の受器内の液層より、ネオジム−鉄合金を液体状
態で取り出すようにしたのである。かくの如く、本発明に従えば、ネオジム−鉄母
合金が電解還元操作の一段階で製造でき、そして
永久磁石の磁気的性質に悪影響を与える酸素等の
不純物や介在物等の含有量が低く、且つネオジム
含有量の高いネオジム−鉄母合金が一段階で効果
的に製造することができることとなつたのであ
る。しかも、固体の陰極を使用するため、陰極の
取扱が容易であることは勿論、生成合金を電解時
の液体合金のままで取り出すために、実質上、電
解を中断することなく、連続操業が可能であり、
そして消耗陰極法の利点である低温操業が連続的
に行ない得る結果、電解成績並びに生成合金品位
が効果的に改善されるのである。また、かかる本発明に従えば、前述したカルシ
ウム等の活性金属による還元法では困難な、操業
の大型化、連続化が達成され、更に酸化ネオジム
を原料とするフツ化物−酸化物混合溶融塩の電解
による製造方法における連続操業上の困難を悉く
回避することができることとなつたのであり、更
にまた塩化ネオジムを原料とする塩化物混合溶融
塩の電解による製造方法では達成できない高電流
効率を長期間にわたつて達成し得るのである。なお、かくの如き本発明手法にあつては、前記
溶融塩電解浴が770〜950℃の温度に保持され、こ
の温度下において前記電解還元操作が進行せしめ
られることが望ましく、またその電解還元操作に
おいては、陽極電流密度：0.05〜0.60A／cm²、陰
極電流密度：0.50〜55A〜cm²の条件が好適に採用
されることとなる。さらに、前記電解還元操作の実施される前記ネ
オジム化合物を含む溶融塩電解浴は、それが実質
的にフツ化ネオジムとフツ化リチウムの二元系に
て構成される場合にあつては、該フツ化ネオジム
が少なくとも40重量％以上、且つ該フツ化リチウ
ムが少なくとも24重量％以上の割合で電解浴中に
存在するように調整せしめられることが望ましい
のである。このように、本発明に従う手法を採用すること
によつて、高性能永久磁石用原料に適した高ネオ
ジム、低不純物含有ネオジム−鉄母合金と、経済
的に且つ大規模、連続的に製造できることとなつ
たのである。そして、このようなネオジム−鉄母
合金は、また、ネオジム金属製造の中間原料とし
ても有利に使用されることとなる。また、かかる本発明を実施するに際しては、(a)
実質的に、フツ化ネオジム及びフツ化リチウム、
並びに必要に応じて添加されたフツ化バリウム、
フツ化カルシウムからなる溶融塩電解浴を収容す
る、耐火性材料から構成された電解槽と、(b)該電
解槽の内面の接浴部に施されたライニングと、(c)
該電解槽の溶融塩電解浴中に挿入、浸漬される、
実質的に長さ方向に形状の変化のない長手の炭素
陽極と、(d)該電解槽の溶融塩電解浴中に挿入、浸
漬される、実質的に長さ方向に形状の変化のない
長手の鉄陰極と、(e)開口部が該鉄陰極の下方に位
置するように、前記電解槽の溶融塩電解浴中に配
置せしめられて、前記炭素陽極と鉄陰極との間に
印加される直流電流によるフツ化ネオジムの電解
還元によつて該鉄陰極上に生じるネオジム−鉄合
金の液滴が滴下せしめられる、かかるネオジム−
鉄合金液滴を集めるための合金受器と、(f)該合金
受器内の液体状態のネオジム−鉄合金を電解槽外
に取り出すための液状合金取出手段と、(g)前記鉄
陰極を、前記ネオジム−鉄合金の生成に伴なうそ
の消耗に従つて、前記電解槽の溶融塩電解浴中に
所定の電流密度が得られるように挿入するための
陰極挿入手段とを、含む装置が好適に用いられ
る。尤も、このようなネオジム−鉄母合金の製造装
置は、更に前記炭素陽極を前記電解槽の溶融塩電
解浴中に所定の電流密度が得られるように挿入す
るための陽極挿入手段や、原料としてのフツ化ネ
オジムを前記電解槽内に供給するための原料供給
手段を備えていることが望ましく、また前記電解
槽の内面に施されるライニングとしては、モリブ
デンン、タングステン等の難融金属材料に代え
て、安価な鉄材料が好適に用いられることとな
る。本発明者らの検討によつて、そのような鉄材
料が優れた耐浴、耐食性を示し、フツ化物電解浴
の場合の良好なライニング材となることが見い出
されたのである。また、本発明にあつては、電解槽内に配置され
た合金受器中に集められた液体状態のネオジム−
鉄合金を、液体状態のままにおいて電解槽外に効
果的に取り出すために、前記液状合金取出手段が
該合金受器内の液状のネオジム−鉄合金中に挿入
されるパイプ状ノズルを有するように構成され、
該ノズルを通じて、真空吸引作用により該ネオジ
ム−鉄合金を吸い上げて、電解槽外に取り出すよ
うにすることが、工業的な実施の観点から有利に
採用されることとなる。（構成の具体的な説明）まず、第１図には、本発明を実施するための電
解システムの模式図が示されているが、そこにお
いて、その電解システムの主要部をなす電解槽２
へは、溶融塩電解浴を構成する溶剤４が装入せし
められるようになつている。そして、この溶剤４
としては、フツ化ネオジム（NdF₃）とフツ化リ
チウム（LiF）が用いられるが、これらに加え
て、フツ化バリウム（BaF₂）とフツ化カルシウ
ム（CaF₂）を単独で或いは両者同時に添加して
用いることも可能である。一方、電解原料は、原
料供給装置６より電解槽２内の電解浴中に供給さ
れることとなるが、本発明では、この原料とし
て、従来の如き酸化ネオジムではなくて、電解浴
の構成成分の一つでもあるフツ化ネオジムが使用
されるのである。また、電解槽２内の電解浴中へは、炭素陽極８
と鉄陰極１０がそれぞれ浸漬せしめられて、それ
ら陽極８と陰極１０との間に直流の電力１２が印
加せしめられることにより、電解浴中のフツ化ネ
オジム原料の電解還元が行なわれるのである。そ
して、この電解還元によつて陰極１０上に析出し
た金属ネオジムは、直ちに陰極１０を構成する鉄
と液体状態の合金を生成せしめ、陰極１０表面よ
り滴下して、電解槽２内の電解浴中に設置した受
器に溜るようになる。なお、上記所定の溶剤組成
のものが溶融する温度では、鉄陰極１０上に生成
する合金は液体状態となるものであり、またその
ような溶融塩からなる電解浴の比重は、生成合金
のそれよりも小さくされているところから、かか
る液体状の合金が鉄陰極１０上に生成されるに従
つて、それは陰極１０表面より下方に落下するよ
うになる。従つて、鉄陰極１０から落下する液体合金を受
ける、該鉄陰極１０の下方に位置する開口部を有
する受器内に溜められた液体合金は、更に適当な
合金取出手段１４によつて電解槽２外へ取り出さ
れ、回収されることとなるのである。なお、電解槽２へは、電解浴、生成合金、電極
（陽極８と陰極１０）、電解槽の構成材料等の変質
を防ぎ、生成合金への有害不純物や介在物の混入
を避けること等のために、保護ガス１６が導入さ
れる。また、電解還元操作にて電解槽２内に発生
したガスは、導入された保護ガスと共に廃ガス処
理装置１８に導かれ、所定の処理が施されるよう
になつている。ところで、かくの如き本発明に従う電解システ
ムにおていは、上述のように、電解原料として、
従来の如き酸化ネオジムとは異なり、フツ化ネオ
ジムが使用される。このフツ化ネオジムを原料と
する場合においては、フツ化ネオジム自体が電解
浴の主要構成成分でもあるところから、電解によ
つてそれが消費される分を供給によつて補うこと
が容易であり、且つ酸化物電解の場合に比較して
遥かに広い原料濃度範囲で電解を継続することが
できるのである。なお、この原料フツ化ネオジム
の供給方法としては、粉末の状態で電解浴の表面
に添加するのが一般的であり、電解浴への溶解速
度も速く、好ましいが、電解浴内にガスと共に導
入する方法或いは粉末の成形体を電解浴中に浸漬
する方法でも行なうことが可能である。また、酸
化ネオジムの電解の場合と比べて、フツ化ネオジ
ムの電解操作においては、電極間の電解領域にお
ける電解原料濃度の許容範囲が遥かに大きく、そ
れ故に供給した原料のかかる領域への移動に遅れ
があつても、電解の継続に支障を来すことが少な
く、従つて原料フツ化ネオジムの供給位置と電解
電気量当たりの供給量に関して、酸化ネオジムを
原料とする場合のような細かい制約を受けず、よ
り任意に選択を行なうことができる利点を有す
る。また、本発明において、不純物や介在物の少な
いネオジム−鉄合金を製造するためには、電解温
度の低下が必要であり、そしてこのために、実質
的に、35〜76％（重量基準。以下同じ）のフツ化
ネオジム、20〜60％のフツ化リチウム、40％まで
のフツ化バリウム、及び20％までのフツ化カルシ
ウムにて構成される、実質的にフツ化物のみより
なる（フツ化ネオジム、フツ化リチウム、フツ化
バリウム、及びフツ化カルシウムの合計量が100
％となる）混合溶融塩が電解浴として選ばれ、そ
してそのような電解浴に、上記した原料フツ化ネ
オジムが添加された場合にあつても、電解中は常
にかかる組成範囲の電解浴となるように調整され
ることとなる。なお、かかる本発明に従う電解浴組成における
フツ化ネオジム濃度が下限未満、即ち35％に満た
ない場合には、電解成績が悪化し、またその上限
濃度（76％）を越えるようになると、電解浴の融
点が上がり過ぎる等の問題を惹起する。また、フ
ツ化リチウムは、その濃度があまりにも低い場合
には電解浴の融点が上がり過ぎ、一方その濃度が
あまりにも高い場合には生成合金との反応が激し
くなつて、電解成績が悪化する等の問題を惹起す
るため、その濃度としては20〜60％に調節する必
要があるのである。さらに、フツ化バリウムやフツ化カルシウム
は、高価なフツ化リチウムの使用量を減少させ、
また形成される混合溶融塩の溶融温度を調節する
等の目的をもつて加えられるものであり、それら
の添加量があまりにも多い場合には、電解浴の融
点が上がり過ぎるところから、前者のフツ化バリ
ウムは40％までの割合で、また後者のフツ化カル
シウムは20％までの割合で、それぞれ単独に或い
は共に用いられることとなる。そして、これら４
成分、即ちフツ化ネオジム、フツ化リチウム、フ
ツ化バリウム、及びフツ化カルシウムの合計量が
実質的に100％となるようにして、電解浴が形成
されるのである。尤も、このような電解浴組成に関して、かかる
電解浴がフツ化ネオジムとフツ化リチウムの二つ
の成分のみにて構成される二元系の場合において
は、フツ化ネオジムは電解浴中において少なくと
も40％以上、フツ化リチウムは少なくとも24％以
上それぞれ存在するように調製されることが望ま
しい。そして、この電解浴成分として用いられる
各フツ化物は、電解及び生成合金の最終用途の物
品特性、例えば永久磁石の磁気特性等に悪影響を
及ぼす不純物を含まなければ、必ずしも高純度の
ものである必要はなく、通常、工業原料に不可避
的に含まれる不純物は、それらが許容できるもの
である限りにおいて電解浴に含まれていても、何
等差支えないのである。なお、電解浴の組成は、
生成せしめられるネオジム−鉄合金の比重より小
さな比重を電解浴が有するように選ばれるもので
あるところから、電解時には、生成されたネオジ
ム−鉄合金が、陰極より比重差によつて電解浴中
を落下し、陰極の下方に位置する開口部を有する
生成合金の受器に容易に到達し得るのである。本発明にあつては、かくの如き組成の電解浴の
電解時の温度は、好適には770℃〜950℃の範囲に
調節せしめられることとなる。前述したように、
電解浴温度があまりにも高くなり過ぎると、生成
合金への不純物、介在物の混入量が許容限度を越
えるようになるからであり、一方あまりにも低い
電解浴温度の場合にあつては、均質な溶融塩電解
浴を形成することが困難となり、電解浴の性状が
悪化し、電解を継続することが困難となるからで
ある。そして、かかる温度範囲では、ネオジムを73重
量％以上含む、高ネオジム濃度のネオジム−鉄合
金が有利に生成せしめられ得るのであり、またそ
の生成合金はこの温度範囲において受器内で液層
を形成し、液体状態での取出しに適しているので
ある。そして、この受器内の液状合金は、電解槽
上部より、真空吸引方式によつて効果的に取り出
すことができる他、下方より流し出し方式によつ
て取り出すことも可能である。しかも、この取出
に際しては、受器内の合金を特別に加熱する必要
もなく、極めて容易に液状合金として電解槽外に
取り出すことができるのである。また、本発明にあつては、電解用電極として、
陰極に鉄、陽極に炭素、特に黒鉛が好適に用いら
れる。陰極の鉄は、不純物を含むと、そのまま生
成合金中に不純物を持ち込むこととなるところか
ら、かかる生成合金を永久磁石用材料として使用
する場合においては、その磁気特性を悪化させる
酸素等の不純物の少ないものを用いることが好ま
しい。また、本発明に従えば、電解操作の進行に
つれて、陰極を構成する鉄は、ネオジム−鉄合金
を生成して、消費されることとなるが、かかる電
解によつて消耗する部分の鉄を補つて、順次、陰
極を電解浴中に浸漬するようにすれば、電解操作
を中断することなく、目的とするネオジム−鉄合
金を連続的に製造することができるのである。そ
の際、陰極の鉄部材の端部にネジ切り加工等を行
なつておいて、ネジ結合等によつて陰極を構成す
る鉄部材を順次接続せしめ、消耗した陰極分を補
うことは、勿論可能である。このように、固体の
鉄が陰極として使用できることは、溶融金属を陰
極として使用する場合に比して、取扱が容易であ
り、且つ電解炉を装置的にみて簡略化し得るとこ
ろから、工業化に際しては、電解炉の大型化が容
易であるという点で大きな利点となるものであ
る。また、かかる本発明に従う炭素陽極を用いるフ
ツ化ネオジムの電解にあつては、陽極全表面にわ
たつての電流密度を、0.05〜0.60A／cm²の範囲内
に、電解操作中常に維持していることが望まし
い。けだし、この電流密度が低過ぎる場合には、
陽極表面積が大き過ぎるか、陽極単位表面積当た
りの電流が小さ過ぎることとなり、このために生
産性が悪化し、工業的に有利ではなくなるからで
あり、またかかる電流密度が高くなり過ぎると、
酸化ネオジムを原料とした場合の陽極効果ないし
はこれと類似の異常現象が発生し易くなるからで
ある。従つて、本発明にあつては、電解条件の一
つとしての陽極電流密度を上記の範囲に保つこと
によつて、そのような異常現象の発生を効果的に
回避することが、推奨されるのである。なお、陽
極表面における局部的な変動を考慮に入れると、
上記陽極全表面にわたつての電流密度は、0.10〜
0.40A／cm²の間に保持することがより好ましい。一方、陰極の電流密度は、陰極全表面にわたつ
ての電流密度として0.50〜55A／cm²の広い範囲に
わたつて許容される。しかし、陰極電流密度があ
まりにも低過ぎると、陰極単位表面積当たりの電
流が小さ過ぎて、生産性が悪化し、工業的ではな
くなる。また、この陰極電流密度が高くなり過ぎ
ると、電解電圧の上昇が甚だしくなり、電解成績
を悪化させる。なお、実際の電解操業の継続に当
たつては、更に1.5〜25A／cm²のより狭い陰極電
流密度の範囲に保つことが、電解電圧の変動幅を
狭く維持し、電解操業を容易にする上において、
より好ましいと言える。さらに、本発明に従えば、電解浴の耐溶材とは
別の炭素を陽極として使用するものであるところ
から、電解浴の耐浴容器（耐浴材）と陽極を兼用
する場合とは異なり、陽極の消耗によつて電解を
終了せしめる必要はなく、ただその消耗分を補つ
て、更に陽極を電解浴中に浸漬するか、或いは複
数の陽極を使用するので、順次新しい陽極に交換
するだけで良い。また、陰極も同様に、その消耗
分を補つて電解浴中に浸漬するか、或いは新しい
陰極に交換するだけで良いのである。本発明で
は、好適に採用される陽極と陰極の表面電流密度
の比の大きな違いにより、陰極の周りに複数本の
陽極を配置して、陽極が陰極と対向するようにし
た電極配列が好適に採用されることとなるが、そ
のような場合において、陽極の交換を順次行なう
ようにすれば、実質上、電解操業を中断すること
なく、ネオジム−鉄合金を連続的に製造すること
ができ、電解法の利点を充分に生かすことができ
る。しかも、陽極形状、陰極形状とも、外形上は
実質的に長さ方向には変化がないものを用いるこ
とができるところから、それらの連続的な使用に
おいて何等の不都合が惹起されることもないので
ある。ところで、かくの如き本発明を実施する電解槽
の構造の好適な一例が、第２図に模式的に示され
ている。かかる第２図において、電解槽２０は、下部槽
２２とその開口部を覆蓋する蓋体２４にて構成さ
れている。また、これら下部槽２２及び蓋体２４
の外側は、通常、鋼等の金属よりなる槽外枠２
６，２８より構成されている。さらに、下部槽２
２及び蓋体２４は、それぞれ外側にレンガやキヤ
スタブル・アルミナ等よりなる耐火断熱材層３
０，３２、及び内側に黒鉛、炭素質スタンプ材等
からなる耐浴材層３４，３６を配置して、構成さ
れている。そして、下部槽２２の内側耐浴材層３４の内面
の接浴面には、ライニング材３８が設けられて、
かかる接浴面を被覆している。このライニング材
３８は、耐浴材層３４からの不純物の混入を防ぐ
他、それがタングステンやモリブデン等の難融金
属にて形成されている場合には、生成する液状ネ
オジム−鉄合金の受器を兼ねることもできる。尤
も、本発明にあつては、かかるライニング材３８
として、安価な鉄材料を用いることが推奨され
る。けだし、本発明者らの検討によつて、安価な
鉄が優れた耐浴、耐食性を示し、フツ化物電解浴
の場合の良好なライニング材となることが見い出
されたからである。また、耐浴材層３４は、必ず
しも必要ではなく、耐火断熱材層３０上に直接に
ライニング材３８を適用しても何等差支えない。また、蓋体２４を貫通するように、１本若しく
は複数本の鉄陰極４０と、この鉄陰極４０に対向
して配置された複数本の炭素陽極４２が設けられ
ており、またそれら両電極４０，４２は、下部槽
２２内に収容される前記所定の溶融塩からなる電
解浴４４中に、所定電流密度となる長さにわたつ
て浸漬されるようになつている。なお、ここで
は、炭素陽極４２，４２は、鉄陰極４０と向かい
合つて配置される陽極のうちの２本が示されてお
り、それらの材質としては黒鉛が好適に用いられ
ることとなる。さらに、これら炭素陽極４２，４２は、棒状、
板状、管状等の形態で用いられ、電解浴４４への
浸漬部分の陽極表面積を大きくして陽極電流密度
を下げるために、公知のように溝付きとすること
もできる。なお、第２図では、炭素陽極４２に
は、電解による陽極消耗の跡を示して、陽極浸漬
部に僅かに傾斜が付けられている。この陽極４２
には、給電のために金属等の適当な導電体の電気
リードが取り付けられていても、何等差支えな
い。また、陽極４２は、陽極挿入手段としての陽
極昇降機構４６によつて上下動せしめられ得るよ
うになつており、これにより電解継続のための適
切な陽極電流密度が確保されるように、間欠的に
或いは連続的に、その浸漬部の表面積を浸漬深さ
で調整し得るようになつている。なお、陽極昇降
機構４６，４６は、陽極への電気接続機能を兼ね
備えることも出来る。一方、陰極４０は、電解還元作用にて析出せし
められる金属ネオジムと合金化させるべき鉄にて
構成されており、ここでは、その１本が示されて
いる。また、第２図では、ネオジム−鉄合金の液
滴生成による陰極消耗の跡を示して、陰極浸漬部
分が円錐形状で示してある。なお、電解温度は、
陰極４０の鉄の融点以下に選ばれるところから、
この鉄陰極４０は固体であり、線状、棒状、板状
等の形態で用いられる。この鉄陰極４０は、ま
た、陰極挿入手段としての陰極昇降機構４８によ
つて合金生成による消耗分を補つて、電解浴４４
中へ連続的或いは間欠的に送り込まれるようにな
つている。そして、この陰極昇降機構４８は、陰
極への電気接続機能を兼ね備えることもできる。
さらに、かかる鉄陰極４０の浸漬部以外の表面
は、防食のために適当な保護スリーブ等で保持す
るようにしても、何等差支えない。また、かかる鉄陰極４０の下方に受器開口部が
位置するように、電解浴４４内において、下部槽
２２の底部上に生成合金受器５０が配置せしめら
れており、電解還元操作によつて鉄陰極４０上に
生成された液状のネオジム−鉄合金５２は、陰極
表面より滴下して、その直下において開口する生
成合金受器５０内に溜められる。なお、この生成
合金受器５０は、生成合金５２との反応性の小さ
な難融金属、例えばタングステン、タンタル、モ
リブデン、ニオブ、或いはそれらの合金等を用い
て形成される他、窒化ホウ素等のホウ化物や酸化
物等のセラミツクス、或いはサーメツト等の材料
を用いて形成することもできる。なお、電解浴４４は、前記した本発明に従う組
成に調整された、フツ化ネオジムを含有するフツ
化物混合溶融塩よりなるものであり、その組成
は、その比重が生成されるネオジム−鉄合金の比
重以下となるように選ばれる。そして、電解によ
つて消費される電解原料は、原料供給装置５４か
ら蓋体２４に設けられた原料供給孔５６を通じて
供給され、所定組成の電解浴４４が形成せしめら
れるようになつている。また、鉄陰極４０から滴下して受器５０内に溜
められた生成合金５２は、それが所定量溜まつた
時に、液体状態のままで所定の合金回収機構（取
出手段）によつて電解槽２０外に取り出されるこ
ととなるが、本発明にあつては、第２図に示され
る如く、パイプ状の真空吸引ノズル５８を、蓋体
２４に設けられた生成合金吸引孔６０を通じて電
解浴４４内に差し入れ、該ノズル５８の先端を生
成合金受器５０内の生成合金５２中に浸漬せし
め、図示されていない真空装置の真空吸引作用を
利用して吸引することにより生成合金５２を吸い
上げて電解炉２０外に取り出す手段が、有利に採
用されることとなる。尤も、このような真空吸引による生成合金５２
の吸引取出し方式に代えて、電解槽２０（下部槽
２２）の下部を貫通する取出パイプを設け、この
取出パイプの先端を更に生成合金受器５０を貫通
させて、該受器５０内に開口せしめることによ
り、かかる取出パイプを通じて、生成合金５２を
炉外下方に流し出す合金回収機構を採用すること
も可能である。なお、図示はされていないが、かかる電解炉２
０内には、保護ガスが供給されるようになつてお
り、また電解操作によつて発生するガスは、かか
る保護ガスと共に、廃ガス出口６２を通じて外部
に排出されるようになつている。また、このよう
な電解槽２０には、前記した電解温度に保持する
ための特別な加熱装置は設けられていないが、所
定の温度に維持するために、必要に応じて、この
電解槽２０内に或いはその外部に適当な加熱装置
を設けてもよいことは、言うまでもないところで
ある。実施例以下、本発明を更に具体的に明らかにするため
に、本発明に従う幾つかの実施例を示すが、本発
明がそのような実施例の記載によつて何等制限的
に解釈されるものでないことは、言うまでもない
ところである。本発明は、上述した本発明の具体的な説明並び
に以下の実施例の他にも、各種の態様において実
施され得るものであり、本発明の趣旨を逸脱しな
い限りにおいて、当業者の知識に基づいて種々な
る態様において実施され得るものは、何れも本発
明の範疇に属するものであることが、理解される
べきである。実施例１ネオジム80％（重量基準。以下同じ）及び鉄18
％の平均組成を有するネオジム−鉄（Nd−Fe）
合金11.3Kgが、次のようにして得られた。すなわち、第２図に示される電解槽と同様な構
成の装置において、電解槽の耐浴材として黒鉛る
つぼを用い、生成合金受器として黒鉛るつぼの底
部中央に設置したモリブデン容器を用いて、実質
上、フツ化ネオジムとフツ化リチウムの二元系フ
ツ化物混合溶融塩よりなる電解浴を不活性ガス雰
囲気中で電解した。陰極としては、黒鉛るつぼ中
央部の電解浴中に同心円状に配置して（平面形態
において）浸漬した、６本の６mmφの鉄線を用
い、陽極としてはかかる陰極の周りに同心円状に
配列して（平面形態において）電解浴中に浸漬し
た、６本の80mmφの黒鉛棒を用いた。そして、フツ化ネオジムを原料として、その粉
末を電解浴に断続的に供給しつつ、下記第１表に
示される範囲内の電解条件を保持して、24時間、
電解を行なつた。この間、電解操業は極めて良好
に継続することができ、液体状のネオジム−鉄合
金が順次滴下して、電解浴内に配置されたモリブ
デンの受器内に溜められた。この溜められた合金
は、８時間毎に、真空吸引ノズルを有する真空吸
引式合金回収装置にて電解炉の外部に取り出され
た。かかる電解操作により得られた電解成績並びに
生成合金の分析結果を、下記第１表及び第２表に
示す。なお、比較のために、同様の製造装置におい
て、原料として酸化ネオジムの粉末を用い、これ
を陰極−陽極間の陽極ガス発生部分（電解領域）
の電解浴に連続供給して、略同様の電解条件下で
電解を行なつたが、その場合には、電解炉底部に
酸化ネオジムのスラツジの形成が電解継続と共に
顕著となり、また陽極効果が頻発した。このた
め、陽極電流密度を更に低下させて、陽極効果の
頻発を防止しようとしたが、その試みも満足な結
果を与えなかつた。また、浴温を更に上げた場合
には、操業面において多少の改善が認められた
が、生成合金中の有害不純物が急激に増加した。実施例２ネオジム88％及び鉄10％の平均組成を有するネ
オジム−鉄合金20.9Kgが、次のような電解操作に
より、実施例１より更に低い温度で得られた。まず、耐浴材としての黒鉛るつぼの内面に鉄を
ライニングしたものを電解浴の容器として用い、
この底部中央に設置したタングステン容器を生成
合金の受器として用いて、実質上、フツ化ネオジ
ムとフツ化リチウムとフツ化バリウムのフツ化物
混合溶融塩よりなる電解浴を、不活性ガス雰囲気
中で電解した。陰極としては、実施例１と同様に
配置した３本の12mmφの鉄棒を用い、また陽極と
しては実施例１と同様の80mmφの黒鉛棒を用い
た。そして、フツ化ネオジムを原料として、電解浴
に断続的にその供給を行ないつつ、下記第１表に
示される範囲内に電解条件を保持したところ、48
時間にわたり良好な電解操業が継続された。ま
た、液体状のネオジム−鉄合金が順次滴下して、
タングステン受器内に集められた。さらに、この
集められた受器内の生成合金は、実施例１と同様
に液体状態で取り出すことができた。かかる電解操作によつて得られた電解成績並び
に生成合金の分析結果を、それぞれ下記第１表及
び第２表に示す。なお、比較のために、同様の製造装置を用い
て、実施例１と同様に、酸化ネオジムを原料とす
る電解を試みたが、酸化ネオジムのスラツジ形成
と陽極効果の発生が更に激しくなり、電解操作を
継続して行なうことができなかつた。実施例３ネオジム84％及び鉄14％の平均組成のネオジム
−鉄合金6.6Kgが、次のような電解操作を採用す
ることによつて、実施例１より更に低い温度で得
られた。すなわち、鉄るつぼを電解槽の耐浴容器として
用い、この底部中央に、実施例１と同様な生成合
金受器を設置し、実質上、フツ化ネオジムとフツ
化リチウムの二元系フツ化物混合溶融塩よりなる
電解浴を、不活性ガス雰囲気下において電解し
た。陰極としては、実施例２と同様な12mmφの鉄
棒を用い、陽極としては陰極の周りに同心円状に
配列した（平面形態において）５本の60mmφの黒
鉛棒を用いた。そして、フツ化ネオジムを原料として電解浴に
連続供給を行ないつつ、下記第１表に示される範
囲内の電解条件を保つて、24時間にわたり良好な
電解操作を継続することができた。また、液体状
のネオジム−鉄合金が順次滴下して、モリブデン
容器内に溜められた。さらに、この溜められた合
金は、実施例１と同様にして、液体状態にて電解
槽から取り出された。かかる電解操作によつて得られた電解成績並び
に生成合金の分析結果を、それぞれ下記第１表及
び第２表に示す。なお、本実施例にあつては、陰極電流密度の上
限を抑えて、狭い範囲内に陰極電流密度を保つこ
とによつて、電解時の電圧の上昇が防止され、電
圧の変動幅が改善された。実施例４ネオジム90％及び鉄８％の平均組成のネオジム
−鉄合金4.6Kgが、次のような電解操作によつて、
前記実施例２及び実施例３よりも更に低い温度で
得られた。すなわち、実施例３と同様に鉄るつぼを電解槽
の耐浴容器として用い、そしてこの底部中央に、
実施例２と同様な生成合金受器を設置し、実質
上、フツ化ネオジムとフツ化リチウムとの二元系
フツ化物混合溶融塩よりなる電解浴を、不活性ガ
ス雰囲気中において電解した。陰極としては34mm
φの１本の鉄棒を用い、また陽極としては実施例
３と同様な60mmφの黒鉛棒を用いた。そして、フツ化ネオジムを原料として、これを
電解浴に連続的に供給しつつ、下記第１表に示さ
れる範囲内の電解条件に保持して、電解を行なう
ことにより、18時間にわたり電解操作を継続して
行なうことができた。なお、液体状のネオジム−
鉄合金が順次滴下して、タングステン容器内に溜
められた。この溜められた合金は、８時間毎に、
第２図の如きノズルを有する真空吸引式合金回収
装置にて電解槽から取り出された。なお、この真
空吸引式合金回収装置のノズル部は、電解槽内に
挿入されるに先立つて、予熱された。また、かかる電解操作によつて得られた電解成
績並びに生成合金の分析結果が、それぞれ下記第
１表及び第２表に示されている。 (Technical Field) The present invention relates to a method and apparatus for producing a neodymium-iron master alloy, and particularly to a neodymium-iron alloy,
In particular, it relates to a method and apparatus for continuously producing a neodymium-iron alloy with a high neodymium content and a low content of harmful impurities and inclusions, which is suitable as a master alloy for high-performance permanent magnets. . (Background of the Invention) Recently, rare earth-iron and rare earth-iron-boron permanent magnets have been attracting attention as high-performance magnets that do not contain expensive samarium or cobalt and have better magnetic properties than hard ferrite. . Among them, neodymium-iron-boron magnets have a maximum energy product (BH)max of 36MGOe or more, and are recognized to be extremely superior in terms of specific gravity and mechanical strength (for example, Showa 59-
(See Publication No. 46008). Both neodymium-iron and neodymium-iron-boron permanent magnets require raw materials with few impurities that degrade magnetic properties, and especially for neodymium raw materials with high reactivity, those with low impurities such as oxygen are manufactured. It has become necessary to establish an industrial method to do so. By the way, neodymium metal has had almost no use in the past, and its production methods generally involve using active metals,
In particular, only the reduction method using calcium and the molten salt electrolysis method are known, and no industrial production method has been fully established. Therefore, even if there is an industrial method for producing neodymium-iron master alloy suitable as a raw material for high-performance permanent magnets as described above, it has not been sufficiently established. Under such circumstances, the following methods of producing neodymium-iron master alloys can be considered based on the conventional state of the art, but each method has various problems, and none of them are possible. However, this method is not fully satisfactory as an industrial or practical method for continuously producing a neodymium-iron master alloy. (a) A method in which neodymium metal is first produced in advance by a reduction method using an active metal such as calcium or by a molten salt electrolysis method, and then iron is added, remelted, and alloyed: In some cases, there is a problem with the initial neodymium manufacturing process. That is, the reduction method using active metals such as calcium is a batch method and is not suitable for continuous large-scale production. In addition, in the molten salt electrolysis method, electrolysis of a chloride electrolytic bath (for example, Jiro Shiokawa et al., "Electrochemistry", Vol. 35, 1967
, p. 496) and the electrolysis of oxides (Nd ₂ O ₃ ) dissolved in fluoride electrolytic baths (E. Morris et al.
"USBur.Min., Rep.Invest.", No.6957, 1967
However, there are problems with electrolytic performance and operation methods, and a method suitable for continuous large-scale production has not been established. (b) A method of mixing neodymium compounds and iron or iron compounds and alloying them while reducing with a suitable reducing agent such as calcium: As mentioned above, the reduction method is generally carried out in a batch method. It is no exception that this method is not suitable for very continuous large-scale production due to the (c) A method in which a compound of neodymium and a compound of iron are dissolved in an electrolytic bath consisting of a suitable molten salt and deposited as an alloy of neodymium and iron on a non-consumable cathode by simultaneous electrolysis of these compounds: This method is more economical than method (d) because it is difficult to stabilize the resulting alloy composition, and iron can be produced in large quantities and at low cost by another method without using molten salt electrolysis. inferior in some respects. (d) Using iron itself as a cathode, neodymium oxide (Nd ₂ O ₂ ) as a neodymium compound is electrolytically reduced in an electrolytic bath of a suitable molten salt to precipitate metallic neodymium on the cathode and at the same time reduce the amount of the cathode. The so-called consumable cathode method for alloying with iron: Regarding this method, an example of research in which a neodymium-iron alloy is obtained by supplying neodymium oxide into a fluoride electrolytic bath and performing electrolysis (E. Morris et al., ``U.S.
Bur. Min., Rep. Invest., No. 7146, 1968), and is considered to be an excellent method without the drawbacks of methods (a) to (c) mentioned above. There are various inherent difficulties. That is, in the electrolysis method using this neodymium oxide as a raw material, the solubility of neodymium oxide in the selected electrolytic bath is as low as about 2%, and as is the purpose of the present invention, it is difficult to obtain a metal with few impurities. Then, since the temperature of the electrolytic bath is selected to be low, its solubility further decreases, and as a result,
It is extremely difficult to dissolve neodymium oxide in the electrolytic bath, and the raw material cannot be continuously and stably supplied. And for this reason, (1)
An abnormal phenomenon peculiar to molten salt electrolysis called the anode effect frequently occurs due to insufficient supply of raw materials to the electrolytic bath; (2) undissolved raw materials prevent the coalescence of formed alloy droplets; (3) undissolved Dissolved raw materials accumulate at the bottom of the electrolytic bath and form so-called sludge, resulting in deterioration of the quality of the produced alloy due to the inclusion of inclusions, etc., and deterioration of the raw material utilization rate (yield). (4) Anode (5) It sometimes becomes difficult to continue electrolysis itself, which makes continuous industrial operation difficult. (Summary of the Invention) The present invention has been made against the background of the above, and its purpose is to make neodymium-iron master alloys particularly suitable for manufacturing high-performance permanent magnets. neodymium-iron matrix alloy,
The purpose is to provide a method and equipment for producing it continuously on a large scale, and another purpose is to provide neodymium that has a high neodymium content and a low content of harmful impurities and inclusions. - To provide a reliable and economical industrial manufacturing method and apparatus for iron master alloys. That is, in order to achieve the above object, the present invention electrolytically reduces a neodymium compound in a molten salt electrolytic bath using an iron cathode and a carbon anode,
When the generated neodymium is precipitated on the iron cathode and alloyed with iron constituting the cathode to form a neodymium-iron alloy, neodymium fluoride is used as the neodymium compound, and
The molten salt electrolytic bath containing such a neodymium compound contains substantially 35-76% by weight of neodymium fluoride, 20
The neodymium-iron alloy is deposited in a liquid state onto the iron cathode while being prepared to consist of ~60% by weight lithium fluoride, up to 40% by weight barium fluoride, and up to 20% by weight calcium fluoride. The neodymium-iron alloy in the liquid state is dropped as droplets into a receiver having an opening in the electrolytic bath below the iron cathode to collect as a liquid layer, and the liquid layer in the receiver is Therefore, the neodymium-iron alloy was extracted in a liquid state. As described above, according to the present invention, a neodymium-iron master alloy can be produced in one step of the electrolytic reduction operation, and the content of impurities such as oxygen and inclusions that adversely affect the magnetic properties of permanent magnets is low. , and a neodymium-iron master alloy with a high neodymium content can be effectively produced in one step. Furthermore, since a solid cathode is used, the cathode is not only easy to handle, but also allows for continuous operation without interrupting electrolysis since the produced alloy can be taken out as a liquid alloy during electrolysis. and
As a result of continuous low-temperature operation, which is an advantage of the consumable cathode method, the electrolytic performance and the quality of the produced alloy are effectively improved. Furthermore, according to the present invention, it is possible to achieve large-scale and continuous operation, which is difficult to achieve with the above-mentioned reduction method using active metals such as calcium. It has become possible to avoid all the difficulties in continuous operation in the production method using electrolysis, and it has also been possible to maintain high current efficiency for a long period of time, which cannot be achieved with the production method using electrolysis of chloride mixed molten salt using neodymium chloride as the raw material. This can be achieved over a period of time. In addition, in the method of the present invention as described above, it is desirable that the molten salt electrolytic bath is maintained at a temperature of 770 to 950°C, and that the electrolytic reduction operation is performed at this temperature. In this case, conditions of anode current density: 0.05 to 0.60 A/cm ² and cathode current density: 0.50 to 55 A/cm ² are suitably adopted. Furthermore, if the molten salt electrolytic bath containing the neodymium compound in which the electrolytic reduction operation is carried out is substantially composed of a binary system of neodymium fluoride and lithium fluoride, It is desirable that the proportion of neodymium oxide present in the electrolytic bath be at least 40% by weight and the lithium fluoride present in an amount of at least 24% by weight. As described above, by employing the method according to the present invention, a high neodymium, low impurity-containing neodymium-iron master alloy suitable as a raw material for high-performance permanent magnets can be produced economically, on a large scale, and continuously. It became. Such a neodymium-iron master alloy can also be advantageously used as an intermediate raw material for producing neodymium metal. Furthermore, when implementing the present invention, (a)
Substantially neodymium fluoride and lithium fluoride,
and barium fluoride added as necessary.
an electrolytic cell made of a refractory material that accommodates a molten salt electrolytic bath made of calcium fluoride; (b) a lining applied to the inner surface of the electrolytic cell in contact with the bath; and (c)
inserted and immersed in the molten salt electrolytic bath of the electrolytic tank;
(d) a longitudinal carbon anode with substantially no change in shape in the longitudinal direction; and (d) a longitudinal carbon anode with substantially no change in shape in the longitudinal direction, which is inserted and immersed in the molten salt electrolytic bath of the electrolytic cell. an iron cathode of (e) disposed in a molten salt electrolytic bath of the electrolytic cell such that an opening is located below the iron cathode, and an electric current applied between the carbon anode and the iron cathode; Droplets of neodymium-iron alloy produced on the iron cathode by electrolytic reduction of neodymium fluoride with a direct current are dropped.
an alloy receiver for collecting the iron alloy droplets, (f) a liquid alloy take-out means for taking out the liquid neodymium-iron alloy in the alloy receiver to the outside of the electrolytic cell, and (g) the iron cathode. , a cathode insertion means for inserting the neodymium-iron alloy into the molten salt electrolytic bath of the electrolytic cell so as to obtain a predetermined current density as the neodymium-iron alloy is consumed as it is produced. Suitably used. However, such a neodymium-iron master alloy production apparatus further includes an anode insertion means for inserting the carbon anode into the molten salt electrolytic bath of the electrolytic tank so as to obtain a predetermined current density, and a material as a raw material. It is desirable to have a raw material supply means for supplying neodymium fluoride into the electrolytic cell, and the lining applied to the inner surface of the electrolytic cell is made of a refractory metal material such as molybdenum or tungsten. Instead, an inexpensive iron material will be suitably used. Through studies conducted by the present inventors, it has been discovered that such iron materials exhibit excellent bath resistance and corrosion resistance, and can serve as a good lining material for fluoride electrolytic baths. In addition, in the present invention, neodymium in a liquid state collected in an alloy receiver placed in an electrolytic cell is used.
In order to effectively take out the iron alloy out of the electrolytic cell in a liquid state, the liquid alloy removal means has a pipe-shaped nozzle inserted into the liquid neodymium-iron alloy in the alloy receiver. configured,
From the viewpoint of industrial implementation, it is advantageous to suck up the neodymium-iron alloy through the nozzle by vacuum suction and take it out of the electrolytic cell. (Specific description of the configuration) First, FIG. 1 shows a schematic diagram of an electrolytic system for carrying out the present invention.
A solvent 4 constituting a molten salt electrolytic bath is charged into the tank. And this solvent 4
Neodymium fluoride (NdF ₃ ) and lithium fluoride (LiF) are used as fluoride, but in addition to these, barium fluoride (BaF ₂ ) and calcium fluoride (CaF ₂ ) may be added alone or both at the same time. It is also possible to use On the other hand, the electrolytic raw material is supplied from the raw material supply device 6 into the electrolytic bath in the electrolytic cell 2, but in the present invention, the raw material is not neodymium oxide as in the conventional case, but is a component of the electrolytic bath. Neodymium fluoride, which is also one of the In addition, a carbon anode 8 is introduced into the electrolytic bath in the electrolytic bath 2.
and iron cathode 10 are respectively immersed, and direct current power 12 is applied between the anode 8 and cathode 10, thereby electrolytically reducing the neodymium fluoride raw material in the electrolytic bath. The metal neodymium deposited on the cathode 10 by this electrolytic reduction immediately forms a liquid alloy with iron constituting the cathode 10, drips from the surface of the cathode 10, and enters the electrolytic bath in the electrolytic cell 2. The water will accumulate in the receiver installed in the area. Note that at the temperature at which the above-mentioned predetermined solvent composition melts, the alloy formed on the iron cathode 10 is in a liquid state, and the specific gravity of the electrolytic bath made of such a molten salt is equal to that of the formed alloy. As such liquid alloy is formed on the iron cathode 10, it falls below the cathode 10 surface. Therefore, the liquid alloy collected in a receiver having an opening located below the iron cathode 10, which receives the liquid alloy falling from the iron cathode 10, is further transferred to the electrolytic cell by suitable alloy removal means 14. 2.It will be taken out and collected. In addition, the electrolytic bath 2 must be prepared to prevent deterioration of the electrolytic bath, the produced alloy, the electrodes (anode 8 and the cathode 10), the constituent materials of the electrolytic cell, etc., and to avoid the mixing of harmful impurities and inclusions into the produced alloy. For this purpose, a protective gas 16 is introduced. Further, the gas generated in the electrolytic cell 2 during the electrolytic reduction operation is led to the waste gas treatment device 18 together with the introduced protective gas, and is subjected to a predetermined treatment. By the way, in the electrolytic system according to the present invention, as described above, as the electrolytic raw material,
Unlike the conventional neodymium oxide, neodymium fluoride is used. When this neodymium fluoride is used as a raw material, since neodymium fluoride itself is the main component of the electrolytic bath, it is easy to supplement the amount consumed by electrolysis by supplying it. Furthermore, electrolysis can be continued over a much wider raw material concentration range than in the case of oxide electrolysis. The raw material neodymium fluoride is generally supplied to the surface of the electrolytic bath in the form of a powder, which is preferable because it dissolves quickly into the electrolytic bath. It is also possible to carry out the method by immersing a powder compact in an electrolytic bath. Furthermore, compared to the electrolysis of neodymium oxide, in the electrolytic operation of neodymium fluoride, the permissible range of the concentration of the electrolytic raw material in the electrolytic region between the electrodes is much larger, and therefore the transfer of the supplied raw material to this region is difficult. Even if there is a delay, it is unlikely to interfere with the continuation of electrolysis, and therefore there are no small restrictions on the supply position of the raw material neodymium fluoride and the supply amount per amount of electricity for electrolysis, as in the case of using neodymium oxide as the raw material. This has the advantage that the selection can be made more arbitrarily. In addition, in the present invention, in order to produce a neodymium-iron alloy with few impurities and inclusions, it is necessary to lower the electrolysis temperature, and for this purpose, the electrolytic temperature is reduced by 35 to 76% (by weight, below). consisting essentially of fluoride (neodymium fluoride), 20-60% lithium fluoride, up to 40% barium fluoride, and up to 20% calcium fluoride , the total amount of lithium fluoride, barium fluoride, and calcium fluoride is 100
%) is selected as the electrolytic bath, and even if the above raw material neodymium fluoride is added to such an electrolytic bath, the electrolytic bath will always have this composition range during electrolysis. It will be adjusted as follows. Note that if the neodymium fluoride concentration in the electrolytic bath composition according to the present invention is less than the lower limit, that is, less than 35%, the electrolytic performance will deteriorate, and if it exceeds the upper limit concentration (76%), the electrolytic bath This causes problems such as the melting point of the material becoming too high. In addition, if the concentration of lithium fluoride is too low, the melting point of the electrolytic bath will rise too much, while if the concentration is too high, the reaction with the formed alloy will be intense, resulting in poor electrolysis results, etc. To avoid this problem, it is necessary to adjust the concentration to 20-60%. Furthermore, barium fluoride and calcium fluoride reduce the amount of expensive lithium fluoride used,
They are also added for the purpose of adjusting the melting temperature of the mixed molten salt that is formed, and if the amount added is too large, the melting point of the electrolytic bath will rise too much. Barium fluoride may be used in a proportion of up to 40%, and the latter calcium fluoride may be used in a proportion of up to 20%, either alone or together. And these 4
The electrolytic bath is formed such that the total amount of the components, namely neodymium fluoride, lithium fluoride, barium fluoride, and calcium fluoride, is substantially 100%. However, regarding such an electrolytic bath composition, if the electrolytic bath is a binary system consisting of only two components, neodymium fluoride and lithium fluoride, neodymium fluoride should account for at least 40% of the electrolytic bath. As mentioned above, it is desirable that lithium fluoride be prepared so that it is present in an amount of at least 24% or more. Each fluoride used as a component of this electrolytic bath must be of high purity as long as it does not contain impurities that adversely affect the properties of the end-use product of the electrolyzed and produced alloy, such as the magnetic properties of permanent magnets. Impurities that are normally included unavoidably in industrial raw materials may be included in the electrolytic bath as long as they are tolerable. The composition of the electrolytic bath is
Since the electrolytic bath is selected to have a specific gravity smaller than the specific gravity of the neodymium-iron alloy to be produced, during electrolysis, the neodymium-iron alloy produced flows through the electrolytic bath more than the cathode due to the difference in specific gravity. It falls and can easily reach a receiver of the resulting alloy, which has an opening located below the cathode. In the present invention, the temperature during electrolysis of the electrolytic bath having such a composition is preferably adjusted within the range of 770°C to 950°C. As previously mentioned,
If the electrolytic bath temperature becomes too high, the amount of impurities and inclusions mixed into the produced alloy will exceed the permissible limit, while if the electrolytic bath temperature is too low, the resulting alloy will not be homogeneous. This is because it becomes difficult to form a molten salt electrolytic bath, the properties of the electrolytic bath deteriorate, and it becomes difficult to continue electrolysis. In this temperature range, a neodymium-iron alloy with a high neodymium concentration containing 73% by weight or more of neodymium can be advantageously produced, and the produced alloy forms a liquid layer in the receiver in this temperature range. Therefore, it is suitable for extraction in a liquid state. The liquid alloy in this receiver can be effectively taken out from the upper part of the electrolytic cell by a vacuum suction method, and can also be taken out from the bottom by a pouring method. Furthermore, when taking out the alloy, there is no need to specially heat the alloy in the receiver, and the alloy can be taken out of the electrolytic cell very easily as a liquid alloy. In addition, in the present invention, as an electrode for electrolysis,
Iron is preferably used for the cathode, and carbon, particularly graphite, is preferably used for the anode. If the iron of the cathode contains impurities, the impurities will be introduced into the produced alloy. Therefore, when such a produced alloy is used as a material for a permanent magnet, it is necessary to avoid impurities such as oxygen that deteriorate the magnetic properties of the produced alloy. It is preferable to use less. Further, according to the present invention, as the electrolytic operation progresses, the iron constituting the cathode produces a neodymium-iron alloy and is consumed, but the iron that is consumed by such electrolysis is supplemented. By sequentially immersing the cathode in the electrolytic bath, the desired neodymium-iron alloy can be produced continuously without interrupting the electrolytic operation. At that time, it is of course possible to perform thread cutting on the end of the iron member of the cathode, and then connect the iron members that make up the cathode one by one using screw connections, etc., to compensate for the consumed cathode. It is. In this way, the fact that solid iron can be used as a cathode is easier to handle than when molten metal is used as a cathode, and the electrolytic furnace can be simplified in terms of equipment, so it is useful for industrialization. This is a great advantage in that it is easy to increase the size of the electrolytic furnace. Further, in the electrolysis of neodymium fluoride using the carbon anode according to the present invention, the current density over the entire surface of the anode is constantly maintained within the range of 0.05 to 0.60 A/cm ² during the electrolysis operation. It is desirable to be present. However, if this current density is too low,
This is because either the anode surface area is too large or the current per unit anode surface area is too small, which deteriorates productivity and is not industrially advantageous, and if the current density becomes too high,
This is because when neodymium oxide is used as a raw material, an anode effect or similar abnormal phenomena are likely to occur. Therefore, in the present invention, it is recommended to effectively avoid the occurrence of such abnormal phenomena by keeping the anode current density as one of the electrolytic conditions within the above range. It is. Furthermore, if local fluctuations on the anode surface are taken into account,
The current density over the entire surface of the anode is 0.10~
More preferably, it is maintained between 0.40 A/cm ² . On the other hand, the current density of the cathode is allowed over a wide range of 0.50 to 55 A/cm ² as the current density over the entire surface of the cathode. However, if the cathode current density is too low, the current per unit surface area of the cathode will be too small, resulting in poor productivity and not being industrially viable. Furthermore, if this cathode current density becomes too high, the electrolytic voltage will increase significantly and the electrolytic results will deteriorate. In addition, when continuing the actual electrolysis operation, it is recommended to keep the cathode current density within a narrower range of 1.5 to 25 A/cm ² to maintain a narrow variation range of the electrolysis voltage and facilitate the electrolysis operation. Above,
It can be said that it is more preferable. Furthermore, according to the present invention, since carbon different from the melt-resistant material of the electrolytic bath is used as the anode, unlike the case where the bath-resistant container (bath-resistant material) of the electrolytic bath also serves as the anode, There is no need to terminate electrolysis due to the consumption of the anode; the consumption can simply be compensated for by further immersing the anode in the electrolytic bath, or since multiple anodes are used, they can be replaced with new anodes one after another. good. Similarly, the cathode only needs to be immersed in an electrolytic bath to compensate for its consumption, or replaced with a new cathode. In the present invention, due to the large difference in the surface current density ratio between the anode and cathode, it is preferable to use an electrode arrangement in which a plurality of anodes are arranged around the cathode so that the anode faces the cathode. In such cases, if the anodes are replaced sequentially, neodymium-iron alloy can be produced continuously without interrupting the electrolytic operation. The advantages of the electrolytic method can be fully utilized. Moreover, since both the anode shape and the cathode shape can be used with an external shape that does not substantially change in the length direction, there will be no inconvenience caused in their continuous use. be. Incidentally, a preferred example of the structure of an electrolytic cell implementing the present invention is schematically shown in FIG. 2. In FIG. 2, the electrolytic cell 20 is composed of a lower tank 22 and a lid 24 that covers the opening thereof. In addition, these lower tank 22 and lid body 24
The outside of the tank is usually a tank outer frame 2 made of metal such as steel.
It is composed of 6,28. Furthermore, lower tank 2
2 and the lid body 24 each have a fireproof insulation layer 3 made of brick, castable alumina, etc. on the outside.
0 and 32, and bath-resistant material layers 34 and 36 made of graphite, carbonaceous stamp material, etc. are arranged inside. A lining material 38 is provided on the inner surface of the inner bath-resistant material layer 34 of the lower tank 22 in contact with the bath.
The bath contact surface is coated. This lining material 38 not only prevents impurities from entering from the bath-resistant material layer 34, but also serves as a receiver for the liquid neodymium-iron alloy that is formed when it is made of a refractory metal such as tungsten or molybdenum. It can also serve as However, in the present invention, such lining material 38
Therefore, it is recommended to use inexpensive iron materials. This is because, through studies conducted by the present inventors, it has been found that inexpensive iron exhibits excellent bath resistance and corrosion resistance, and is a good lining material for fluoride electrolytic baths. Further, the bath-resistant material layer 34 is not necessarily required, and there is no problem in applying the lining material 38 directly on the fire-resistant heat insulating material layer 30. Further, one or more iron cathodes 40 and a plurality of carbon anodes 42 arranged opposite to the iron cathodes 40 are provided so as to penetrate through the lid body 24, and both of these electrodes 40 , 42 are immersed in an electrolytic bath 44 made of the predetermined molten salt housed in the lower tank 22 over a length that provides a predetermined current density. Here, two carbon anodes 42, 42 are shown among the anodes disposed facing the iron cathode 40, and graphite is preferably used as their material. Furthermore, these carbon anodes 42, 42 are rod-shaped,
It is used in the form of a plate, a tube, etc., and may be grooved as is known in the art in order to increase the anode surface area of the part immersed in the electrolytic bath 44 and lower the anode current density. In addition, in FIG. 2, the carbon anode 42 has a slight inclination at the anode immersion part, showing traces of anode wear due to electrolysis. This anode 42
There is no problem even if an electrical lead made of a suitable conductor such as metal is attached to the terminal for power supply. Further, the anode 42 can be moved up and down by an anode lifting mechanism 46 serving as an anode insertion means. The surface area of the immersion part can be adjusted by adjusting the immersion depth, either continuously or continuously. Note that the anode lifting and lowering mechanisms 46, 46 can also have the function of electrically connecting to the anode. On the other hand, the cathode 40 is made of iron to be alloyed with metallic neodymium deposited by electrolytic reduction, and one of the cathodes is shown here. Further, in FIG. 2, the cathode immersion portion is shown in a conical shape to show traces of cathode consumption due to droplet formation of the neodymium-iron alloy. In addition, the electrolysis temperature is
Since it is selected below the melting point of the iron of the cathode 40,
This iron cathode 40 is solid and is used in the form of a line, rod, plate, or the like. This iron cathode 40 is also inserted into the electrolytic bath 40 by compensating for the consumption due to alloy formation by a cathode lifting mechanism 48 serving as a cathode insertion means.
It is designed to be fed into the interior continuously or intermittently. The cathode lifting mechanism 48 can also have the function of electrically connecting to the cathode.
Further, the surface of the iron cathode 40 other than the immersed portion may be protected by a suitable protective sleeve or the like for corrosion prevention. In addition, a produced alloy receiver 50 is arranged on the bottom of the lower tank 22 in the electrolytic bath 44 so that the receiver opening is located below the iron cathode 40, and the produced alloy receiver 50 is disposed on the bottom of the lower tank 22 in the electrolytic bath 44. The liquid neodymium-iron alloy 52 produced on the iron cathode 40 drips from the cathode surface and is collected in the produced alloy receiver 50 which opens directly below. The produced alloy receiver 50 is formed using a refractory metal that has low reactivity with the produced alloy 52, such as tungsten, tantalum, molybdenum, niobium, or an alloy thereof, or a boron such as boron nitride. It can also be formed using materials such as ceramics such as compounds or oxides, or cermets. The electrolytic bath 44 is made of a fluoride mixed molten salt containing neodymium fluoride, which has been adjusted to have a composition according to the present invention described above, and its composition has a specific gravity that corresponds to the neodymium-iron alloy to be produced. Selected so that the specific gravity is below. The electrolytic raw material consumed by electrolysis is supplied from a raw material supply device 54 through a raw material supply hole 56 provided in the lid 24, so that an electrolytic bath 44 having a predetermined composition is formed. Furthermore, when a predetermined amount of generated alloy 52 drips from the iron cathode 40 and accumulates in the receiver 50, it is transferred to the electrolytic cell in a liquid state by a predetermined alloy recovery mechanism (retrieval means). However, in the present invention, as shown in FIG. The tip of the nozzle 58 is immersed in the produced alloy 52 in the produced alloy receiver 50, and the produced alloy 52 is sucked up by suction using the vacuum suction action of a vacuum device (not shown) and electrolyzed. Means for taking it out of the furnace 20 will be advantageously employed. However, the alloy 52 produced by such vacuum suction
Instead of the suction extraction method, an extraction pipe is provided that penetrates the lower part of the electrolytic cell 20 (lower tank 22), and the tip of this extraction pipe is further passed through the produced alloy receiver 50, and an opening is made in the receiver 50. By doing so, it is also possible to employ an alloy recovery mechanism that drains the generated alloy 52 downwardly outside the furnace through such a take-out pipe. Although not shown, such an electrolytic furnace 2
A protective gas is supplied into the chamber 0, and the gas generated by the electrolytic operation is discharged to the outside through a waste gas outlet 62 together with the protective gas. Further, although such an electrolytic cell 20 is not provided with a special heating device for maintaining the electrolysis temperature described above, in order to maintain the electrolysis temperature at a predetermined temperature, the inside of this electrolytic cell 20 may be heated as necessary. It goes without saying that a suitable heating device may be provided inside or outside the heating device. Examples In order to clarify the present invention more specifically, some examples according to the present invention will be shown below, but the present invention should not be construed in any way limited by the description of such examples. It goes without saying that this is not the case. The present invention can be implemented in various embodiments in addition to the above-mentioned specific explanation of the present invention and the following examples, and as long as it does not depart from the spirit of the present invention, various embodiments can be implemented based on the knowledge of those skilled in the art. It should be understood that any of the various embodiments that can be implemented in various ways fall within the scope of the present invention. Example 1 Neodymium 80% (weight basis; the same applies hereinafter) and iron 18
Neodymium-iron (Nd-Fe) with an average composition of %
11.3Kg of alloy was obtained as follows. That is, in an apparatus having the same configuration as the electrolytic cell shown in FIG. Above, an electrolytic bath consisting of a binary fluoride mixed molten salt of neodymium fluoride and lithium fluoride was electrolyzed in an inert gas atmosphere. As the cathode, six 6 mm diameter iron wires were arranged concentrically and immersed in the electrolytic bath at the center of the graphite crucible (in planar form), and as the anode, they were arranged concentrically around the cathode. Six 80 mmφ graphite rods immersed in an electrolytic bath (in planar form) were used. Using neodymium fluoride as a raw material, the powder was intermittently supplied to the electrolytic bath while maintaining the electrolytic conditions within the range shown in Table 1 below for 24 hours.
Conducted electrolysis. During this time, the electrolytic operation was able to continue very well, and the liquid neodymium-iron alloy was successively dripped and collected in a molybdenum receiver placed in the electrolytic bath. This accumulated alloy was taken out of the electrolytic furnace every 8 hours using a vacuum suction type alloy recovery device having a vacuum suction nozzle. The electrolytic results obtained by such electrolytic operation and the analysis results of the produced alloy are shown in Tables 1 and 2 below. For comparison, neodymium oxide powder was used as a raw material in a similar manufacturing device, and this was applied to the anode gas generation area (electrolysis area) between the cathode and the anode.
was continuously supplied to the electrolytic bath and electrolysis was performed under almost the same electrolytic conditions, but in that case, the formation of neodymium oxide sludge at the bottom of the electrolytic furnace became noticeable as electrolysis continued, and the anodic effect frequently occurred. did. Therefore, an attempt was made to prevent the frequent occurrence of the anodic effect by further lowering the anode current density, but this attempt did not give satisfactory results. Furthermore, when the bath temperature was further raised, some improvement was observed in terms of operation, but the amount of harmful impurities in the produced alloy increased rapidly. Example 2 20.9 kg of neodymium-iron alloy having an average composition of 88% neodymium and 10% iron was obtained at a lower temperature than in Example 1 by the following electrolytic operation. First, a graphite crucible with iron lining on the inner surface as a bath-resistant material was used as a container for the electrolytic bath.
Using the tungsten container installed at the center of the bottom as a receiver for the produced alloy, an electrolytic bath consisting essentially of a molten fluoride mixture of neodymium fluoride, lithium fluoride, and barium fluoride was heated in an inert gas atmosphere. Electrolyzed. As the cathode, three 12 mmφ iron rods arranged in the same manner as in Example 1 were used, and as the anode, the same 80 mmφ graphite rod as in Example 1 was used. Then, when neodymium fluoride was used as a raw material and the electrolytic conditions were maintained within the range shown in Table 1 below while supplying it intermittently to the electrolytic bath, 48
Good electrolysis operation continued for a long time. In addition, liquid neodymium-iron alloy is sequentially dripped,
collected in a tungsten receiver. Furthermore, the collected alloy produced in the receiver could be taken out in a liquid state as in Example 1. The electrolytic results obtained by such electrolytic operation and the analysis results of the produced alloy are shown in Tables 1 and 2 below, respectively. For comparison, we attempted electrolysis using neodymium oxide as a raw material in the same manner as in Example 1 using the same manufacturing equipment, but the formation of neodymium oxide sludge and the occurrence of the anode effect became even more severe, and the electrolysis failed. It was not possible to continue the operation. Example 3 6.6 kg of neodymium-iron alloy with an average composition of 84% neodymium and 14% iron was obtained at a lower temperature than in Example 1 by employing the following electrolytic operation. That is, an iron crucible is used as a bath-resistant container of an electrolytic cell, and a produced alloy receiver similar to that in Example 1 is installed in the center of the bottom of the crucible, and essentially a binary fluoride mixture of neodymium fluoride and lithium fluoride is mixed. An electrolytic bath consisting of a molten salt was subjected to electrolysis under an inert gas atmosphere. As the cathode, a 12 mmφ iron rod similar to that in Example 2 was used, and as the anode, five 60 mmφ graphite rods arranged concentrically around the cathode (in plan view) were used. While continuously supplying neodymium fluoride as a raw material to the electrolytic bath and maintaining the electrolytic conditions within the range shown in Table 1 below, it was possible to continue good electrolytic operation for 24 hours. In addition, liquid neodymium-iron alloy was sequentially dropped and collected in the molybdenum container. Furthermore, this accumulated alloy was taken out from the electrolytic cell in a liquid state in the same manner as in Example 1. The electrolytic results obtained by such electrolytic operation and the analysis results of the produced alloy are shown in Tables 1 and 2 below, respectively. In addition, in this example, by suppressing the upper limit of the cathode current density and keeping the cathode current density within a narrow range, an increase in voltage during electrolysis is prevented and the voltage fluctuation range is improved. Ta. Example 4 4.6 kg of neodymium-iron alloy with an average composition of 90% neodymium and 8% iron was subjected to the following electrolytic operation.
It was obtained at a lower temperature than in Examples 2 and 3. That is, as in Example 3, an iron crucible was used as the bath-resistant container of the electrolytic cell, and in the center of the bottom,
A produced alloy receiver similar to that in Example 2 was set up, and an electrolytic bath consisting essentially of a binary fluoride mixed molten salt of neodymium fluoride and lithium fluoride was electrolyzed in an inert gas atmosphere. 34mm as cathode
One iron rod with a diameter of 60 mm was used as the anode, and a graphite rod with a diameter of 60 mm similar to that in Example 3 was used as an anode. Then, using neodymium fluoride as a raw material, electrolysis is carried out for 18 hours by continuously supplying it to the electrolytic bath and maintaining the electrolytic conditions within the range shown in Table 1 below. I was able to continue doing this. In addition, liquid neodymium
The iron alloy was dropped one after another and collected in a tungsten container. This accumulated alloy is released every 8 hours.
The alloy was removed from the electrolytic bath using a vacuum suction type alloy recovery device having a nozzle as shown in FIG. Note that the nozzle portion of this vacuum suction type alloy recovery device was preheated before being inserted into the electrolytic cell. Further, the electrolytic results obtained by such electrolytic operation and the analysis results of the produced alloy are shown in Tables 1 and 2 below, respectively.

【表】【table】

【表】かかる第１表及び第２表の結果から明らかなよ
うに、本発明に従つてフツ化ネオジムを電解する
ことにより、ネオジム含有量の高いネオジム−鉄
合金が一挙に製造され得るのであり、またそのよ
うな生成合金は、磁石特性を悪化させる酸素等の
不純物の含有量の低いネオジム−鉄合金であるこ
とが認められる。なお、第２表中の合金含有成分
の数値は、８時間毎に取り出された合金の分析値
の平均値である。また、第２表に示された不純物
以外の不純物は、本実施例の場合、実質上、ネオ
ジム以外の他の希土類金属よりなるものである。
さらに、この第２表には、比較のために、市販さ
れているネオジム金属の分析結果が示されている
が、それら市販ネオジム金属では磁石材料として
有害な酸素等の不純物含有量が高くなつている。また、以上の実施例のうち、実施例１〜３で
は、更に長時間にわたつて継続して電解を行なう
ことが容易であり、そのような場合にあつても、
それぞれの実施例と同様な結果が得られることが
確認されている。[Table] As is clear from the results in Tables 1 and 2, by electrolyzing neodymium fluoride according to the present invention, a neodymium-iron alloy with a high neodymium content can be produced all at once. It is also recognized that such produced alloy is a neodymium-iron alloy with a low content of impurities such as oxygen which deteriorate magnetic properties. Note that the numerical values of the alloy-containing components in Table 2 are the average values of the analysis values of the alloy taken out every 8 hours. Further, in this example, impurities other than those shown in Table 2 are substantially composed of rare earth metals other than neodymium.
Furthermore, Table 2 shows the analysis results of commercially available neodymium metals for comparison, but these commercially available neodymium metals have a high content of impurities such as oxygen that are harmful to magnet materials. There is. Furthermore, among the above examples, in Examples 1 to 3, it is easy to perform electrolysis continuously over a longer period of time, and even in such a case,
It has been confirmed that results similar to those of each example can be obtained.

[Brief explanation of the drawing]

第１図は本発明を実施するための具体的な電解
システムを示す模式図であり、第２図は本発明を
実施するための電解槽の構造の一例を示す断面図
である。２：電解槽、４：溶剤、６：原料供給装置、
８：炭素陽極、１０：鉄陰極、１２：電力、１
４：合金取出手段、１６：保護ガス、１８：廃ガ
ス処理装置、２０：電解槽、２２：下部槽、２
４：蓋体、３０，３２：耐火断熱材層、３４，３
６：耐浴材層、３８：ライニング材、４０：鉄陰
極、４２：炭素陽極、４４：電解浴、４６：陽極
昇降機構、４８：陰極昇降機構、５０：生成合金
受器、５２：生成合金、５４：原料供給装置、５
８：真空吸引ノズル、６０：生成合金吸引孔。 FIG. 1 is a schematic diagram showing a specific electrolytic system for implementing the present invention, and FIG. 2 is a sectional view showing an example of the structure of an electrolytic cell for implementing the present invention. 2: Electrolytic cell, 4: Solvent, 6: Raw material supply device,
8: carbon anode, 10: iron cathode, 12: electric power, 1
4: Alloy extraction means, 16: Protective gas, 18: Waste gas treatment device, 20: Electrolytic cell, 22: Lower tank, 2
4: Lid body, 30, 32: Fireproof insulation layer, 34, 3
6: Bath-resistant material layer, 38: Lining material, 40: Iron cathode, 42: Carbon anode, 44: Electrolytic bath, 46: Anode lifting mechanism, 48: Cathode lifting mechanism, 50: Generated alloy receiver, 52: Generated alloy , 54: Raw material supply device, 5
8: Vacuum suction nozzle, 60: Generated alloy suction hole.

Claims

[Claims] 1. Using an iron cathode and a carbon anode, a neodymium compound is electrolytically reduced in a molten salt electrolytic bath, and the generated neodymium is deposited on the iron cathode, and is alloyed with iron constituting the cathode. to form a neodymium-iron alloy, neodymium fluoride is used as the neodymium compound, and the molten salt electrolytic bath containing the neodymium compound contains substantially 35 to 76% by weight of neodymium fluoride, 20 to 76% by weight. The neodymium-iron alloy is deposited in a liquid state on the iron cathode while being prepared to consist of 60% by weight of lithium fluoride, up to 40% by weight of barium fluoride and up to 20% by weight of calcium fluoride. The neodymium-iron alloy in the liquid state is dropped as droplets into a receiver having an opening in the electrolytic bath below the iron cathode to collect as a liquid layer, and further from the liquid layer in the receiver. A method for producing a neodymium-iron master alloy, characterized in that the neodymium-iron alloy is extracted in a liquid state. 2. The manufacturing method according to claim 1, wherein the molten salt electrolytic bath is maintained at a temperature of 770 to 950°C, and the electrolytic reduction operation is performed at this temperature. 3 The electrolytic reduction operation is performed at an anode current density of 0.05 to
Claim 1 or 2 conducted under the conditions of 0.60A/cm ² and cathode current density: 0.50 to 55A/cm ² .
Manufacturing method described in section. 4. The manufacturing method according to any one of claims 1 to 3, wherein the carbon electrode is a graphite electrode. 5 The molten salt electrolytic bath containing the neodymium compound is
Claims consisting essentially of neodymium fluoride and lithium fluoride, and adjusted so that the neodymium fluoride is present in an amount of at least 40% by weight, and the lithium fluoride is present in an amount of at least 24% by weight, respectively. The manufacturing method according to any one of items 1 to 4. 6. An electrolytic cell made of a refractory material and containing a molten salt electrolytic bath consisting essentially of neodymium fluoride and lithium fluoride, and barium fluoride and calcium fluoride added as necessary; a lining provided on the inner surface of the electrolytic cell in contact with the bath; a longitudinal carbon anode that is inserted into and immersed in the molten salt electrolytic bath of the electrolytic cell and whose shape does not substantially change in the longitudinal direction; an elongated iron cathode that is inserted into and immersed in a molten salt electrolytic bath of an electrolytic cell, the shape of which does not change substantially in the longitudinal direction; placed in a molten salt electrolytic bath of
Neodymium-iron alloy droplets produced on the iron cathode by electrolytic reduction of neodymium fluoride by a direct current applied between the carbon anode and the iron cathode are dropped. an alloy receiver for collecting the neodymium-iron alloy in the liquid state in the alloy receiver, a liquid alloy take-out means for taking out the liquid neodymium-iron alloy in the alloy receiver to the outside of the electrolytic cell; and a cathode insertion means for inserting the cathode into the molten salt electrolytic bath of the electrolytic cell so as to obtain a predetermined current density as the cathode is consumed. Device. 7. The manufacturing apparatus according to claim 6, further comprising anode insertion means for inserting the carbon anode into the molten salt electrolytic bath of the electrolytic cell so as to obtain a predetermined current density. 8. The manufacturing apparatus according to claim 6 or 7, comprising a raw material supply means for supplying neodymium fluoride as a raw material into the electrolytic cell. 9. The liquid alloy extraction means has a pipe-shaped nozzle inserted into the liquid neodymium-iron alloy in the alloy receiver, and sucks up the neodymium-iron alloy through the nozzle by a vacuum suction action, and discharges the neodymium-iron alloy to the outside of the electrolytic cell. Claims 6 to 8 taken out
Manufacturing equipment according to any of the above. 10. The manufacturing apparatus according to any one of claims 6 to 9, wherein the lining is made of iron material. 11. The manufacturing apparatus according to any one of claims 6 to 10, wherein the carbon electrode is a graphite electrode.