JP2015148012A - Method for concentrating rare earth element from rare earth element-containing product - Google Patents

Method for concentrating rare earth element from rare earth element-containing product Download PDF

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JP2015148012A
JP2015148012A JP2015022378A JP2015022378A JP2015148012A JP 2015148012 A JP2015148012 A JP 2015148012A JP 2015022378 A JP2015022378 A JP 2015022378A JP 2015022378 A JP2015022378 A JP 2015022378A JP 2015148012 A JP2015148012 A JP 2015148012A
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rare earth
phase
earth element
enriched
iron
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JP5977385B2 (en
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山口　勉功
Benko Yamaguchi
勉功 山口
英弘 関本
Hidehiro Sekimoto
英弘 関本
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JX Nippon Mining and Metals Corp
Iwate University
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Iwate University
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

PROBLEM TO BE SOLVED: To provide a method for concentrating rare earth elements from a rare earth element-containing product at high concentration ratio.SOLUTION: There is provided a method for concentrating rare earth elements from a rare earth element-containing product including a process 1 for heating and melting the rare earth element-containing product in a co-presence of BOto form a BOphase and a rare earth element rich phase more than the BOphase under the BOphase.

Description

本発明は希土類元素含有物質から希土類元素を濃縮する方法に関する。とりわけ本発明は希土類磁石から希土類元素を濃縮する方法に関する。   The present invention relates to a method for concentrating rare earth elements from a rare earth element-containing substance. In particular, the present invention relates to a method for concentrating rare earth elements from rare earth magnets.

希土類元素は永久磁石、水素吸蔵合金、固体レーザー、ディスプレイ用蛍光体、蛍光灯、セラミックコンデンサ、センサー、燃料電池、着色剤等に使用されている。希土類元素はパソコン、スマートフォン及び電気自動車などを取り扱うハイテク産業に欠かせない物質であり、昨今の電子機器の高度化に伴ってその需要が高まっているが、希少元素であるために産出量が少なく、価格も高騰している。そのため、このようなハイテク機器から希土類を回収し、リサイクルするための技術開発が望まれている。   Rare earth elements are used in permanent magnets, hydrogen storage alloys, solid lasers, phosphors for displays, fluorescent lamps, ceramic capacitors, sensors, fuel cells, colorants, and the like. Rare earth elements are indispensable materials for high-tech industries that handle personal computers, smartphones, electric vehicles, etc., and their demand is increasing with the recent advancement of electronic devices, but they are rare elements, so their output is low. The price is also rising. Therefore, it is desired to develop a technology for collecting and recycling rare earths from such high-tech equipment.

従来の希土類元素の回収方法は、湿式法と乾式法に分けることができる。湿式法では希土類を使用した機器を破砕してスクラップとし、これを酸により溶解し、固液分離や溶媒抽出によって各希土類元素に分離する方法が一般的である。湿式法を開示した文献としては、特許文献１〜３、非特許文献１等が挙げられる。また、乾式法としては、希土類含有物を還元後、ＣａＦ2等のフッ化物フラックスと共に加熱溶融し、フラックス中に酸化物や炭素などの不純物を抽出する方法を開示した特許文献４〜６等が挙げられる。非特許文献２には、Ｎｄ−Ｆｅ−Ｂ系磁石から酸化ホウ素を用いたガラススラグ法によってＮｄが抽出され、酸化ホウ素を主成分とするＮｄ含有ガラススラグ相とＦｅ−Ｂ合金とに分離されることが記載されている。 Conventional methods for recovering rare earth elements can be divided into wet methods and dry methods. In the wet method, a method is generally used in which equipment using rare earth is crushed to scrap, dissolved with acid, and separated into each rare earth element by solid-liquid separation or solvent extraction. References disclosing the wet method include Patent Documents 1 to 3, Non-Patent Document 1, and the like. Also, as a dry method, Patent Documents 4 to 6 and the like that disclose a method of reducing a rare earth-containing material and heating and melting it together with a fluoride flux such as CaF 2 to extract impurities such as oxide and carbon in the flux are disclosed. Can be mentioned. In Non-Patent Document 2, Nd is extracted from an Nd-Fe-B magnet by a glass slag method using boron oxide, and separated into an Nd-containing glass slag phase mainly composed of boron oxide and an Fe-B alloy. It is described that.

特開昭６２−８３４３３号公報JP-A-62-83433 特公平５−１４７７７号公報Japanese Patent Publication No. 5-14777 特開平５−２８７４０５号公報JP-A-5-287405 特開２００１−３３５８１５号公報JP 2001-335815 A 特開２００２−１２９２１号公報JP 2002-12921 A 米国特許第５，１７４，８１１号明細書US Pat. No. 5,174,811

町田憲一、“金属”、Ｖｏｌ．７９、アグネ技術センター、２００９年、ｐｐ．２９−３５Kenichi Machida, “Metal”, Vol. 79, Agne Technical Center, 2009, pp. 29-35 T.Saito他、“ガラススラグ法による廃Nd-Fe-Ｂ合金からのＮｄ抽出(The extraction of Nd from waste Nd-Fe-B alloys by the glass slag method)”、ジャーナルオブアロイズアンドコンパウンズ(Journal of ALLOYS AND COMPOUNDS)、エルビア(Elsevier), 353(2003) pp.189-193T. Saito et al., “The extraction of Nd from waste Nd—Fe—B alloys by the glass slag method”, Journal of Alloys and Compounds ( Journal of ALLOYS AND COMPOUNDS), Elsevier, 353 (2003) pp.189-193

湿式法では酸や沈澱剤を大量に使用するという問題や浸出に時間を要するという問題があることから乾式法が有望であるが、上述した方法以外にも有益な方法や改善策が存在すると考えられる。希土類元素の回収技術は未だ発展途上にあり、多くの選択肢を提供しておくことが今後の技術開発の可能性を広げる観点から望ましいであろう。   In the wet method, the dry method is promising because of the problem of using a large amount of acid and a precipitant and the time required for leaching, but there are thought to be useful methods and improvements other than those described above. It is done. Rare earth element recovery technology is still in the process of development, and it is desirable to provide many options from the viewpoint of expanding the possibilities of future technology development.

ここで、非特許文献２に記載されている酸化ホウ素を使用する方法は興味深いが、酸化ホウ素のガラススラグ相にＮｄを抽出することはできても、Ｎｄが十分に濃縮されているとはいえない。また、非特許文献２は鉄中からの希土類の除去を検討したもので、希土類の回収を前提としていない。本発明は上記事情に鑑みてなされたものであり、希土類元素含有物から希土類元素をより高い濃縮率で濃縮する方法を提供することを課題の一つとする。   Here, although the method using boron oxide described in Non-Patent Document 2 is interesting, although Nd can be extracted into the glass slag phase of boron oxide, it can be said that Nd is sufficiently concentrated. Absent. Non-Patent Document 2 examines the removal of rare earth from iron and does not assume the recovery of rare earth. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for concentrating rare earth elements from a rare earth element-containing material at a higher concentration rate.

本発明者は上記課題を解決するために鋭意検討したところ、以下の知見を得た。希土類元素含有物質を酸化ホウ素（Ｂ2Ｏ3）フラックスの共存下で加熱溶融させると、希土類元素とＢ2Ｏ3を主体とした二元系融体が出現する。この二元系融体は所定条件下では更にＢ2Ｏ3相と、その下のＢ2Ｏ3相よりも希土類元素が富化された相にきれいに二液分離する。更に、希土類元素含有物質中にＦｅが含まれている場合、Ｆｅ相が別途生成する。そのため、この現象を利用すれば、例えば希土類磁石をＢ2Ｏ3相と希土類元素が富化したＲｅxＯy−Ｂ2Ｏ3相とＦｅ相に分離することができる。加熱溶融を炭素等の融点降下剤の共存下で行えば分離性は更に良くなる。この点、非特許文献２ではＢ2Ｏ3を用いているが、上述した二液相分離を利用していない点で大きく異なる。 The present inventor has made extensive studies to solve the above problems, and has obtained the following knowledge. When a rare earth element-containing substance is heated and melted in the presence of boron oxide (B 2 O 3 ) flux, a binary melt mainly composed of rare earth elements and B 2 O 3 appears. The binary melts further B 2 and O 3 phase, rare earth elements than B 2 O 3 phase below it cleanly two-liquid separated phase enriched in certain conditions. Furthermore, when the rare earth element-containing material contains Fe, an Fe phase is separately generated. Therefore, by utilizing this phenomenon, it is possible, for example a rare earth magnet B 2 O 3 phase and a rare earth element is separated into Re x O y -B 2 O 3 phase and Fe phase enriched. Separation is further improved by heating and melting in the presence of a melting point depressant such as carbon. In this respect, B 2 O 3 is used in Non-Patent Document 2, but is greatly different in that the two-liquid phase separation described above is not used.

本発明は上記知見を基礎として完成したものであり、一側面において、希土類元素含有物質をＢ2Ｏ3の共存下で加熱溶融し、Ｂ2Ｏ3相と、Ｂ2Ｏ3相よりも下方にＢ2Ｏ3相よりも希土類元素が富化された相とを形成する工程１を含む希土類元素含有物質からの希土類元素濃縮方法である。 The present invention has been completed on the basis of the above findings, in one aspect, by heating and melting a rare earth element-containing material in the presence of B 2 O 3, the lower and B 2 O 3 phase, than B 2 O 3 phase And a method of enriching a rare earth element from a rare earth element-containing material, comprising the step 1 of forming a phase enriched with a rare earth element rather than a B 2 O 3 phase.

本発明に係る希土類元素濃縮方法の一実施形態においては、工程１は、１１５０〜１６００℃で１０〜３６０分保持した後、冷却することを含む。   In one embodiment of the rare earth element enrichment method according to the present invention, step 1 includes holding at 1150 to 1600 ° C. for 10 to 360 minutes and then cooling.

本発明に係る希土類元素濃縮方法の別の一実施形態においては、希土類元素含有物質が鉄を含有し、工程１では前記希土類元素が富化された相の下方に又は当該相に包囲されるように、Ｂ2Ｏ3相及び前記希土類元素が富化された相の何れの相よりも鉄が富化された相を更に形成する。 In another embodiment of the rare earth element enrichment method according to the present invention, the rare earth element-containing material contains iron, and in step 1, the rare earth element-enriched phase is surrounded by or under the phase. In addition, an iron-enriched phase is further formed than any of the B 2 O 3 phase and the phase enriched with the rare earth element.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、工程１を融点降下剤の共存下で行う。   In still another embodiment of the rare earth element concentration method according to the present invention, step 1 is performed in the presence of a melting point depressant.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、融点降下剤が炭素である。   In still another embodiment of the rare earth element enrichment method according to the present invention, the melting point depressant is carbon.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、炭素の供給源がＦｅ−Ｃ合金である。   In yet another embodiment of the rare earth element enrichment method according to the present invention, the carbon source is an Fe-C alloy.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、工程１を酸化剤の共存下で行う。   In still another embodiment of the rare earth element concentration method according to the present invention, step 1 is performed in the presence of an oxidizing agent.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、酸化剤が酸化鉄である。   In still another embodiment of the rare earth element enrichment method according to the present invention, the oxidizing agent is iron oxide.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、Ｂ2Ｏ3相中の希土類元素の総質量に対する前記希土類元素が富化された相中の希土類元素の総質量の比が１０以上である。 In yet another embodiment of the rare earth element enrichment method according to the present invention, the ratio of the total mass of the rare earth element in the phase enriched with the rare earth element to the total mass of the rare earth element in the B 2 O 3 phase is 10 or more.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、希土類元素にＮｄ、Ｄｙ及びＰｒから選択される少なくとも一種が含まれる。   In still another embodiment of the rare earth element enrichment method according to the present invention, the rare earth element includes at least one selected from Nd, Dy, and Pr.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、希土類元素含有物質は希土類磁石を原料とする。   In yet another embodiment of the rare earth element enrichment method according to the present invention, the rare earth element-containing material is made from a rare earth magnet.

本発明に係る希土類元素濃縮方法の更に別の一実施形態においては、希土類磁石がネオジム磁石である。   In still another embodiment of the rare earth element enrichment method according to the present invention, the rare earth magnet is a neodymium magnet.

本発明によれば、希土類元素が含まれる材料から希土類元素を高濃縮することができるようになる。そのため、本発明は例えば希土類磁石等の希土類元素を含有する使用済み製品から各成分を分離回収し、リサイクルするための要素技術として極めて有益である。   According to the present invention, a rare earth element can be highly concentrated from a material containing the rare earth element. Therefore, the present invention is extremely useful as an elemental technology for separating and recovering each component from a used product containing rare earth elements such as a rare earth magnet and recycling it.

本発明に係る方法によって加熱処理した後の試料（例１）の断面写真の例である。It is an example of the cross-sectional photograph of the sample (Example 1) after heat-processing by the method which concerns on this invention.

本発明に係る希土類元素含有物質からの希土類元素濃縮方法の一実施形態においては、希土類元素含有物質をＢ2Ｏ3の共存下で加熱溶融し、Ｂ2Ｏ3相と、Ｂ2Ｏ3相よりも下方にあってＢ2Ｏ3相よりも希土類元素が富化された相（以下、「希土類富化相」という。）とを形成する工程１を含む。 In one embodiment of the rare earth element concentration method of a rare earth element-containing substance according to the present invention, a rare earth element-containing material is heated and melted in the presence of B 2 O 3, and B 2 O 3 phase, B 2 O 3 phase And a phase 1 that is lower than the B 2 O 3 phase and is enriched in the rare earth element (hereinafter referred to as “rare earth enriched phase”).

（１．希土類元素含有物質）
希土類元素含有物質としては、希土類元素、すなわちＳｃ（スカンジウム）、Ｙ（イットリウム）、Ｌａ（ランタン）、Ｃｅ（セリウム）、Ｐｒ（プラセオジム）、Ｎｄ（ネオジム）、Ｐｍ（プロメチウム）、Ｓｍ（サマリウム）、Ｅｕ（ユウロピウム）、Ｇｄ（ガドリニウム）、Ｔｂ（テルビウム）、Ｄｙ（ジスプロシウム）、Ｈｏ（ホルミウム）、Ｅｒ（エルビウム）、Ｔｍ（ツリウム）、Ｙｂ（イッテルビウム）、Ｌｕ（ルテチウム）の１７元素の何れか１種以上を含有する物質であれば特に制限はない。典型的な実施形態においては、希土類元素含有物質にはＮｄ、Ｐｒ、Ｓｍ及びＤｙから選択される少なくとも一種が含まれる。希土類元素含有物質は混合物、化合物、焼結物、合金、及びこれらの組み合わせなど種々の形態を取ることができる。 (1. Rare earth element-containing substances)
As the rare earth element-containing substance, rare earth elements, that is, Sc (scandium), Y (yttrium), La (lanthanum), Ce (cerium), Pr (praseodymium), Nd (neodymium), Pm (promethium), Sm (samarium) , Eu (europium), Gd (gadolinium), Tb (terbium), Dy (dysprosium), Ho (holmium), Er (erbium), Tm (thulium), Yb (ytterbium), Lu (lutetium) If it is a substance containing 1 or more types, there will be no restriction | limiting in particular. In a typical embodiment, the rare earth-containing material includes at least one selected from Nd, Pr, Sm and Dy. The rare earth-containing material can take various forms such as a mixture, a compound, a sintered product, an alloy, and a combination thereof.

本発明が処理対象とする希土類元素含有物質の典型例を挙げると、希土類元素は永久磁石、水素吸蔵合金、固体レーザー、ディスプレイ用蛍光体、蛍光灯、セラミックコンデンサ、センサー、燃料電池、着色剤等に使用されることから、これらの使用済み製品や、製品の製造過程で排出される端材などである。また、希土類元素含有物質は粉状や塊状を含め、何れの形状でも構わないので、加熱溶融前に予め粉砕する必要はない。従って、廃棄されたそのままの形態で処理することもできる。但し、磁石を処理するときは、安全性の観点から、加熱等の方法によって予め消磁しておくことが好ましい。   Typical examples of rare earth-containing materials to be treated by the present invention include rare earth elements such as permanent magnets, hydrogen storage alloys, solid lasers, phosphors for displays, fluorescent lamps, ceramic capacitors, sensors, fuel cells, colorants, etc. These are used products and scrap materials discharged in the manufacturing process of products. Moreover, since the rare earth element-containing substance may be in any shape including powder and lump, it is not necessary to pulverize it before heating and melting. Therefore, it can also be processed in the discarded form. However, when processing the magnet, it is preferable to demagnetize in advance by a method such as heating from the viewpoint of safety.

希土類元素を用いて作られる永久磁石は希土類磁石と呼ばれており、ネオジム磁石（例：Ｎｄ−Ｆｅ−Ｂ系）、サマリウムコバルト磁石（例：Ｓｍ−Ｃｏ系）、プラセオジム磁石（例：Ｐｒ−Ｃｏ系）、サマリウム鉄窒素磁石（例：Ｓｍ−Ｆｅ−Ｎ系）等が知られている。希土類磁石はモーター、自動車、ＭＲＩ、ハードディスク、ヘッドホン等への利用が多い。希土類磁石には希土類元素の他に鉄が含まれていることが多い。湿式法を用いた場合には、鉄分を酸浸出するのに多くの時間及びコストを費やす必要があったが、後述するように、本発明に係る方法によれば、酸浸出することなく、鉄を相分離可能である。   Permanent magnets made from rare earth elements are called rare earth magnets, and are neodymium magnets (eg, Nd—Fe—B series), samarium cobalt magnets (eg: Sm—Co series), praseodymium magnets (eg, Pr— Co-based), samarium iron-nitrogen magnets (example: Sm-Fe-N-based), and the like are known. Rare earth magnets are often used in motors, automobiles, MRI, hard disks, headphones, and the like. Rare earth magnets often contain iron in addition to rare earth elements. When the wet method is used, it is necessary to spend a lot of time and cost for acid leaching of iron, but as described later, according to the method of the present invention, iron leaching can be performed without acid leaching. Can be phase separated.

また、製品によっては耐食性や電磁波シールド性を高めるために各種のめっきが施されているものもある。めっきは予め研磨等で除去した方が希土類富化相の純度を高める点で好ましいが、ニッケル、銅、クロム、リンなど主要なめっき成分は鉄と挙動を同じくするので、希土類富化相への混入は僅かである。そのため、経済性も考慮すれば、めっきを除去することなく加熱溶融に供する方が実用的である。   Some products are subjected to various types of plating in order to improve corrosion resistance and electromagnetic shielding properties. It is preferable to remove the plating in advance by polishing or the like in terms of increasing the purity of the rare earth-enriched phase, but the main plating components such as nickel, copper, chromium and phosphorus have the same behavior as iron, so There is little contamination. For this reason, it is more practical to heat and melt without removing the plating, considering the economy.

（２．希土類希土類富化相形成）
希土類元素含有物質をＢ2Ｏ3フラックスの共存下で加熱溶融すると、希土類元素とＢ2Ｏ3を主体とした二元系融体が出現する。加熱溶融温度を適正化することにより、この融体は比重差によって上部のＢ2Ｏ3相と、下部の希土類富化相とに二液分離する。二液分離に適した温度は１１５０〜１６００℃であり、後述するＦｅ相中への希土類元素の分配率を下げるためには、１４００℃以下が好ましく、１２５０℃以下がより好ましい。加熱溶融温度が高すぎると二液分離しないために、Ｂ2Ｏ3と希土類元素の混在した相が生成するのみであり、希土類元素の十分な濃縮ができない。 (2. Formation of rare earth-rare earth-enriched phase)
When a rare earth element-containing substance is heated and melted in the presence of a B 2 O 3 flux, a binary melt mainly composed of a rare earth element and B 2 O 3 appears. By optimizing the heating and melting temperature, this melt is separated into two liquids by the specific gravity difference into an upper B 2 O 3 phase and a lower rare earth-enriched phase. The temperature suitable for the two-component separation is 1150 to 1600 ° C., and is preferably 1400 ° C. or less and more preferably 1250 ° C. or less in order to lower the distribution ratio of the rare earth element in the Fe phase described later. If the heating and melting temperature is too high, the two-component separation is not performed, so that only a phase in which B 2 O 3 and a rare earth element are mixed is generated, and the rare earth element cannot be sufficiently concentrated.

高い分離性を得る観点からは、上記温度範囲に１０分以上保持し溶融状態にすることが好ましく、６０分以上保持することがより好ましい。但し、保持時間が長すぎても理論的な分配比を超えた効果は生じないことから、経済性を考慮すれば、保持時間は３６０分以下とするのが好ましく、２４０分以下とするのがより好ましい。   From the viewpoint of obtaining high separability, it is preferable that the temperature range be maintained for 10 minutes or more to be in a molten state, and it is more preferable to hold for 60 minutes or more. However, since the effect exceeding the theoretical distribution ratio does not occur even if the holding time is too long, considering the economy, the holding time is preferably 360 minutes or less, and preferably 240 minutes or less. More preferred.

希土類富化相中の希土類元素はＢ2Ｏ3とＲｅ2Ｏ3の液体が均一に溶け合った形態で存在していると考えられ、希土類富化相とＢ2Ｏ3富化相の二液相分離を発生させるために（これより低い値だと化合物固体と液相、または化合物固相のみとなる。）２モルの希土類元素に対して３モルのＢ2Ｏ3が必要である。そのため、Ｂ2Ｏ3は、希土類元素含有物質に含まれる希土類元素に対して少なくとも１．５倍のモル比で共存させることが望ましく、希土類富化相を生成させるためには１．５倍以上のＢ2Ｏ3が必要な理由から１．５倍以上のモル比で共存させることが好ましい。上限は特に設定されないが、余剰なＢ2Ｏ3の存在によりエネルギー消費が多くなるので、Ｂ2Ｏ3は希土類元素含有物質に含まれる希土類元素に対して５以下のモル比とするのが好ましく、４以下のモル比とするのがより好ましい。 The rare earth element in the rare earth-enriched phase is considered to exist in a form in which the B 2 O 3 and Re 2 O 3 liquids are uniformly dissolved, and the two liquids of the rare earth-enriched phase and the B 2 O 3 -enriched phase In order to cause phase separation (lower values would result in compound solid and liquid phase or compound solid phase only), 3 mol of B 2 O 3 is required for 2 mol of rare earth elements. Therefore, it is desirable that B 2 O 3 coexists with a rare earth element contained in the rare earth element-containing substance at a molar ratio of at least 1.5 times, and in order to generate a rare earth-enriched phase, it is 1.5 times or more. It is preferable to coexist at a molar ratio of 1.5 times or more because of the necessity of B 2 O 3 . The upper limit is not particularly set, but energy consumption increases due to the presence of excess B 2 O 3 , and therefore B 2 O 3 is preferably set to a molar ratio of 5 or less with respect to the rare earth element contained in the rare earth element-containing substance. More preferably, the molar ratio is 4 or less.

二液分離させた後、上記温度範囲よりも高い温度に加熱することは二液分離性を悪化させるので避けるべきであるが、当該温度範囲に保持する前にいったん当該温度範囲よりも高温に加熱しておくことは鉄など高融点物質中に混入している希土類元素を溶かし出す上で有効である。従って、加熱溶融時の温度変化としては、二液分離に好適な上記温度範囲に加熱し、その後冷却する場合と、均質な融体を形成するために二液分離に好適な上記温度範囲よりも高温（例えば１６００℃以上）に加熱して、次いで、温度を低下させて二液分離に好適な上記温度範囲に保持し、その後冷却する場合がある。   Heating to a temperature higher than the above temperature range after two-component separation should be avoided as it degrades the two-component separation, but once heated to a temperature higher than the temperature range before maintaining the temperature range. It is effective to dissolve rare earth elements mixed in a high melting point material such as iron. Therefore, the temperature change at the time of heating and melting is higher than the above temperature range suitable for two-component separation in order to form a homogeneous melt by heating to the above temperature range suitable for two-component separation and then cooling. There is a case where heating is performed at a high temperature (for example, 1600 ° C. or higher), and then the temperature is decreased to maintain the above temperature range suitable for two-component separation, followed by cooling.

Ｂ2Ｏ3相は典型的にはＢ2Ｏ3を８０質量％以上、より典型的にはＢ2Ｏ3を９０質量％以上含有する。希土類富化相はＢ2Ｏ3相よりも希土類元素が富化された相であり、典型的にはＢ2Ｏ3を３０〜７０質量％、より典型的にはＢ2Ｏ3を４０〜６０質量％、更により典型的にはＢ2Ｏ3を４０〜５０質量％含有する。本発明の一実施形態によれば、Ｂ2Ｏ3相中の希土類元素の総質量に対する希土類富化相中の希土類元素の総質量の比を１０以上とすることができ、好ましくは２０以上とすることができ、より好ましくは２５以上とすることができ、例えば１０〜４０とすることができ、２０〜３０とすることもできる。 B 2 O 3 phase is typically B 2 O 3 of 80 wt% or more, more typically contain B 2 O 3 90 wt% or more. The rare earth-enriched phase is a phase enriched with rare earth elements rather than the B 2 O 3 phase, typically 30 to 70% by mass of B 2 O 3 , more typically 40 to 40% of B 2 O 3 . 60% by weight, still more typically 40-50% by weight of B 2 O 3 . According to one embodiment of the present invention, the ratio of the total mass of rare earth elements in the rare earth-enriched phase to the total mass of rare earth elements in the B 2 O 3 phase can be 10 or more, preferably 20 or more. More preferably 25 or more, for example, 10 to 40, or 20 to 30.

希土類元素含有物質が鉄を含有するときは、希土類富化相の下方に又は希土類富化相に包囲されるように、Ｂ2Ｏ3相及び希土類富化相の何れの相よりも鉄が富化された相（以下、「Ｆｅ相」という。）を更に形成することができる。一般に、Ｆｅ相は希土類富化相よりも比重が大きいので、下方に位置するが、鉄の量が少ないと鉄が丸まってしまい、希土類富化相に包囲されるように、Ｆｅ相が形成される。本発明の一実施形態によれば、Ｂ2Ｏ3相中のＦｅの総質量に対するＦｅ相中のＦｅの総質量の比を１００以上とすることができ、好ましくは５００以上とすることができ、より好ましくは１０００以上とすることができ、例えば１００〜２０００とすることができ、５００〜１５００とすることもできる。また、本発明の一実施形態によれば、希土類富化相中のＦｅの総質量に対するＦｅ相中のＦｅの総質量の比を１０以上とすることができ、好ましくは５０以上とすることができ、より好ましくは１００以上とすることができ、例えば１０〜２００とすることができ、５０〜１５０とすることもできる。 When the rare earth-containing material contains iron, it is richer in iron than either the B 2 O 3 phase or the rare earth-enriched phase so that it is below the rare earth-enriched phase or surrounded by the rare earth-enriched phase. It is possible to further form a transformed phase (hereinafter referred to as “Fe phase”). Generally, the Fe phase has a higher specific gravity than the rare earth-enriched phase, so it is located below, but when the amount of iron is small, the iron is rounded, and the Fe phase is formed so that it is surrounded by the rare earth-enriched phase. The According to an embodiment of the present invention, the ratio of the total mass of Fe in the Fe phase to the total mass of Fe in the B 2 O 3 phase can be 100 or more, preferably 500 or more. More preferably, it can be 1000 or more, for example, it can be set to 100-2000, and can also be set to 500-1500. Further, according to one embodiment of the present invention, the ratio of the total mass of Fe in the Fe phase to the total mass of Fe in the rare earth-enriched phase can be 10 or more, preferably 50 or more. More preferably, it can be set to 100 or more, for example, can be set to 10-200, and can also be set to 50-150.

更に、本発明の一実施形態によれば、Ｆｅ相中の希土類元素の総質量に対する希土類富化相中の希土類元素の総質量の比を１０以上とすることができ、好ましくは１００以上とすることができ、より好ましくは１０００以上とすることができ、例えば１０〜３０００とすることができ、１０００〜３０００とすることもできる。   Furthermore, according to one embodiment of the present invention, the ratio of the total mass of rare earth elements in the rare earth-enriched phase to the total mass of rare earth elements in the Fe phase can be 10 or more, preferably 100 or more. More preferably 1000 or more, for example, 10 to 3000, or 1000 to 3000.

鉄の融点は１５３８℃と高いことから、二液分離の効率と溶解時のエネルギー低減を考慮すると、融点降下剤の共存下で工程１を実施するのが好ましい。融点降下剤としては、鉄の融点を下げることのできる物質であれば特に制限はないが、炭素、リン、ボロン、シリコン、硫黄、ヒ素、アンチモンなどが挙げられる。これらは単独で使用することもでき、二種類以上を組み合わせて使用することもできる。   Since the melting point of iron is as high as 1538 ° C., considering the efficiency of two-component separation and energy reduction during dissolution, it is preferable to carry out step 1 in the presence of a melting point depressant. The melting point depressant is not particularly limited as long as it is a substance capable of lowering the melting point of iron, and examples thereof include carbon, phosphorus, boron, silicon, sulfur, arsenic, and antimony. These can also be used independently and can also be used in combination of 2 or more types.

融点降下剤の中でも炭素は、鉄の酸化を防ぎ、鉄がＢ2Ｏ3相へ移動するのを防止する効果があり、分離性が向上するので好ましい。炭素の供給源としては、限定的ではないが、加熱炉に炭素るつぼを使用すること、炉壁を炭素コーティングすること、銑鉄等のＦｅ−Ｃ合金、コークス、グラファイト、プラスチック、有機物等を添加剤として反応系に添加すること、二酸化炭素、炭化水素系ガスなどの炭素源を吹き込むこと等が挙げられる。コークスやグラファイトは加熱溶融時に酸化し、ほとんどはガスとなって系外に排出されるので、各相に対する汚染物質となる心配も少ない一方で、系外に排出されやすいので融点降下や酸化防止効果としては弱くなる。一方、Ｆｅ−Ｃ合金の場合、炭素が合金中に組み込まれており、加熱溶融中も容易には系外に排出されないので、融点降下や酸化防止効果はコークスやグラファイトに比べて高い。そして、Ｆｅは分離性がよいので添加することによる弊害はない。よって、炭素の供給源としてＦｅ−Ｃ合金が優れている。 Among melting point depressants, carbon is preferable because it has an effect of preventing the oxidation of iron, preventing the iron from moving to the B 2 O 3 phase, and improving the separability. The source of carbon is not limited, however, it is possible to use a carbon crucible in the heating furnace, coat the furnace wall with carbon, Fe-C alloy such as pig iron, coke, graphite, plastic, organic matter, etc. And adding a carbon source such as carbon dioxide or hydrocarbon gas to the reaction system. Coke and graphite are oxidized when heated and melted, and most of them are discharged out of the system as a gas, so there is little concern about becoming a pollutant for each phase. As it becomes weaker. On the other hand, in the case of an Fe—C alloy, carbon is incorporated in the alloy and is not easily discharged out of the system even during heating and melting, so that the melting point drop and the antioxidant effect are higher than those of coke and graphite. And since Fe is separable, there is no harmful effect caused by adding it. Therefore, an Fe—C alloy is excellent as a carbon supply source.

融点降下剤の添加量は、溶融温度が最も低くなるという理由により共晶点の組成付近とすることが好ましい。融点降下剤として炭素を使用する場合は、炭素飽和の状態、すなわち融体中にそれ以上炭素が溶け込まない状態で加熱溶融を行うことが融点降下や酸化防止効果の観点で好ましい。   The addition amount of the melting point depressant is preferably in the vicinity of the composition of the eutectic point because the melting temperature is the lowest. When carbon is used as the melting point depressant, it is preferable from the viewpoint of melting point depressing and antioxidation effects to perform heat melting in a carbon saturated state, that is, in a state where no further carbon is dissolved in the melt.

加熱溶融時の雰囲気は特に制限はなく、大気雰囲気下で実施すれば足りる。しかしながら、鉄の酸化を防止する観点からは、Ａｒや窒素などの不活性雰囲気下で実施するのが好ましい。鉄が酸化するとＢ2Ｏ3相へ移行し易くなるからである。 The atmosphere at the time of heating and melting is not particularly limited, and it is sufficient to carry out in an air atmosphere. However, from the viewpoint of preventing iron oxidation, it is preferably carried out in an inert atmosphere such as Ar or nitrogen. This is because when iron is oxidized, it becomes easy to shift to the B 2 O 3 phase.

鉄の酸化は回避すべきである一方で、希土類元素の酸化を促進することは、相分離性を良くする観点で好ましい。また、ネオジム磁石にはホウ素が含まれているが、このホウ素を酸化することによりＢ2Ｏ3とすることが望まれる。そこで、工程１を鉄の酸化が促進されない程度の酸化性条件下で加熱溶融を行うことが好ましい。このような観点からみた本発明に適した酸化剤としては、空気、二酸化炭素、酸化鉄（三酸化二鉄、四酸化三鉄）、酸化鉄を含む複合酸化物、酸化ボロン、一酸化炭素、亜硫酸ガス等が挙げられ、回収される鉄の不純物を低減する観点から空気、二酸化炭素、酸化鉄が好ましい。 While oxidation of iron should be avoided, promoting oxidation of rare earth elements is preferable from the viewpoint of improving phase separation. Moreover, although the neodymium magnet contains boron, it is desirable to oxidize this boron to B 2 O 3 . Therefore, it is preferable to heat and melt the process 1 under oxidizing conditions that do not promote the oxidation of iron. From this viewpoint, the oxidizing agent suitable for the present invention includes air, carbon dioxide, iron oxide (diiron trioxide, triiron tetroxide), complex oxide containing iron oxide, boron oxide, carbon monoxide, A sulfurous acid gas etc. are mentioned, and air, a carbon dioxide, and iron oxide are preferable from a viewpoint of reducing the impurity of the iron collect | recovered.

酸化剤の添加量は、鉄を酸化させない理由により希土類元素に対して酸素量が１．５〜２．０倍のモル比とすることが好ましい。   The addition amount of the oxidizing agent is preferably a molar ratio of 1.5 to 2.0 times the amount of oxygen with respect to the rare earth element for the reason of not oxidizing iron.

ここで、非特許文献２との違いについて述べると、非特許文献２では不活性雰囲気の実験であり、適切な酸化剤も添加されていないことから、添加したＢ2Ｏ3が磁石中の希土類金属と次の反応をすることにより還元され、以下の反応式に従って鉄中のボロン濃度が増加する。
Ｎｄ2Ｆｅ14Ｂ＋Ｂ2Ｏ3＝Ｎｄ2Ｏ3＋３Ｆｅ2Ｂ＋８Ｆｅ
このことから非特許文献２の方法では、鉄中のホウ素は全くといっていいほど除去できない。鉄の再利用を考えると、鉄中にホウ素が含まれない本方法が望ましいと考えられる。この点、本発明によれば、上述した希土類元素を酸化し、鉄は酸化させないような酸化性条件下で加熱溶融を行うことにより、Ｆｅ相中にホウ素はほとんど混入しないようにすることが可能である。 Here, the difference from Non-Patent Document 2 will be described. Since Non-Patent Document 2 is an experiment in an inert atmosphere and no appropriate oxidant is added, the added B 2 O 3 is added to the rare earth in the magnet. It is reduced by the following reaction with the metal, and the boron concentration in iron increases according to the following reaction formula.
Nd 2 Fe 14 B + B 2 O 3 = Nd 2 O 3 + 3Fe 2 B + 8Fe
For this reason, in the method of Non-Patent Document 2, boron in iron cannot be removed at all. Considering the reuse of iron, it is considered desirable to use this method in which boron is not contained in iron. In this regard, according to the present invention, it is possible to hardly mix boron in the Fe phase by performing heat melting under oxidizing conditions that oxidize the rare earth elements described above and do not oxidize iron. It is.

（３．分離回収）
各相が形成された後は、溶融状態にある間に各相を分液することにより、希土類富化相を含めて各相を分離回収することができる。Ｂ2Ｏ3相は工程１に再利用することができる。分液の方法としては、比重の重い相から順番に炉底から排出する方法がある。比重の軽い相は炉の上部から抽出してもよい。また、冷却して固化させてから、相の境界に沿ってカッター等で切断してもよい。冷却する際は、分離性を挙げるために、固化するまでは徐冷するのが好ましい。 (3. Separation and recovery)
After each phase is formed, each phase including the rare earth-enriched phase can be separated and recovered by separating each phase while it is in a molten state. The B 2 O 3 phase can be reused in step 1. As a method of liquid separation, there is a method of discharging from the bottom of the furnace in order from a phase with a higher specific gravity. The light phase may be extracted from the top of the furnace. Moreover, after cooling and solidifying, it may cut | disconnect with a cutter etc. along the boundary of a phase. When cooling, it is preferable to slowly cool until solidification in order to increase separability.

分離回収された希土類富化相は公知の任意の処理に供することができる。例えば、シュウ酸、塩酸、硫酸等を用いた酸浸出を行って希土類元素を溶解した後、水酸化アンモニウム、硫酸化アンモニウム、水酸化ナトリウム等を添加してｐＨ調整することによって希土類元素の塩を析出する。酸化ホウ素は液中に溶解したままであるので、固液分離することによって希土類元素の塩を回収可能である。上述した乾式処理によって、予め鉄が除去されているので、浸出に要する酸の量は格段に小さくて済む。その後、溶融塩電解やＣａ還元などの方法によって希土類元素を単体として回収することができる。希土類元素の塩を焼成することで希土類酸化物として回収することもできる。   The rare earth-enriched phase separated and recovered can be subjected to any known treatment. For example, after leaching with oxalic acid, hydrochloric acid, sulfuric acid or the like to dissolve the rare earth element, the salt of the rare earth element is adjusted by adding ammonium hydroxide, ammonium sulfate, sodium hydroxide or the like to adjust the pH. Precipitate. Since boron oxide remains dissolved in the liquid, the salt of the rare earth element can be recovered by solid-liquid separation. Since the iron is previously removed by the dry treatment described above, the amount of acid required for leaching is much smaller. Thereafter, the rare earth element can be recovered as a simple substance by a method such as molten salt electrolysis or Ca reduction. It can also be recovered as a rare earth oxide by firing a salt of a rare earth element.

＜例１＞
加熱して消磁した市販のネオジム磁石を鉄乳鉢によって粉砕し実験に供した。ネオジム磁石にはＮｉ−Ｃｕ−Ｎｉの三層めっきが施されていたが、表面を研磨してめっき層を除去した。ＩＣＰ−ＡＥＳを用いて決定されためっき除去後の試料の組成を表１に示す。 <Example 1>
A commercially available neodymium magnet that had been demagnetized by heating was crushed with an iron mortar and used for the experiment. The neodymium magnet was subjected to Ni—Cu—Ni three-layer plating, but the surface was polished to remove the plating layer. Table 1 shows the composition of the sample after plating removal determined by using ICP-AES.

（単位：質量％） (Unit: mass%)

ネオジム磁石試料（５．０ｇ）、Ｂ2Ｏ3（１０ｇ）、Ｆｅ2Ｏ3（１．２ｇ）を、Ｃを４．３質量％含むＦｅ−Ｃ合金（７．５ｇ）と共に炭素るつぼへ装入した。Ｆｅ2Ｏ3はネオジム磁石中の希土類元素とホウ素を酸化させるために加えた。試料を１１７０℃で１時間、アルゴン雰囲気中で加熱保持した後、アルゴンガスを吹き付けて急冷した。相の分離を目視で確認した後、各相成分をＩＣＰ−ＡＥＳを用いて分析した。 A neodymium magnet sample (5.0 g), B 2 O 3 (10 g), and Fe 2 O 3 (1.2 g) are loaded into a carbon crucible together with an Fe—C alloy (7.5 g) containing 4.3% by mass of C. I entered. Fe 2 O 3 was added to oxidize rare earth elements and boron in the neodymium magnet. The sample was heated and held at 1170 ° C. for 1 hour in an argon atmosphere, and then quenched by blowing argon gas. After visually confirming phase separation, each phase component was analyzed using ICP-AES.

上記実験によって得られた試料の写真を図１に示す。図１から分かるように、試料が三相に分離している。表２に示す各相の分析結果からみて、これら三相は鉛直方向に上から順にネオジムを１．２５質量％程度含むＢ2Ｏ3相、黒緑色のネオジム、ジスプロシウム、プラセオジム等の希土類元素が富化されたＮｄ2Ｏ3−Ｂ2Ｏ3相、そして最下相の希土類元素をほとんど含んでいないＦｅ−Ｃ合金相であった。 A photograph of the sample obtained by the above experiment is shown in FIG. As can be seen from FIG. 1, the sample is separated into three phases. From the analysis results of each phase shown in Table 2, these three phases are rare earth elements such as B 2 O 3 phase containing about 1.25% by mass of neodymium in the vertical direction from the top, black-green neodymium, dysprosium, praseodymium and the like. It was an enriched Nd 2 O 3 —B 2 O 3 phase and an Fe—C alloy phase containing almost no rare earth element in the lowest phase.

（単位：質量％） (Unit: mass%)

表２より、Ｂ2Ｏ3相中の希土類元素の総質量に対する希土類富化相（Nd2O3-B2O3相）中の希土類元素の総質量の比は２５．７であり、Ｆｅ相（Fe-C合金相）中の希土類元素の総質量に対する希土類富化相中の希土類元素の総質量の比は５９６．４であった。上記実験結果より、磁石中の希土類元素をＮｄ2Ｏ3−Ｂ2Ｏ3相へ濃縮することが可能であることが分かる。表中で、Ｆｅ−Ｃ合金相におけるＢ2Ｏ3が「−」となっているが、これはＢ2Ｏ3としては検出されなかったという意味である。なお、Ｂとしては０．２７質量％検出された。 From Table 2, the total weight ratio of rare earth elements in the rare earth-rich phase with respect to the total mass (Nd 2 O 3 -B 2 O 3 phases) of rare earth elements B 2 O 3 phase is 25.7, Fe The ratio of the total mass of the rare earth element in the rare earth-enriched phase to the total mass of the rare earth element in the phase (Fe—C alloy phase) was 596.4. From the above experimental results, it can be seen that the rare earth element in the magnet can be concentrated to the Nd 2 O 3 —B 2 O 3 phase. In the table, B 2 O 3 in the Fe—C alloy phase is “−”, which means that it was not detected as B 2 O 3 . In addition, 0.27 mass% was detected as B.

＜例２＞
例１と同様のネオジム磁石を粉砕せずに塊の状態で実験に供した。ネオジム磁石にはＮｉ−Ｃｕ−Ｎｉの三層めっきが施されていたが、表面を研磨してめっき層を除去した。ネオジム磁石試料（２０ｇ）及びＢ2Ｏ3（１０ｇ）を、Ｃを４．３質量％含むＦｅ−Ｃ合金（２０ｇ）と共に炭素るつぼへ挿入した。試料を１１７０℃で２１．５時間、二酸化炭素雰囲気中で加熱保持した後、アルゴンガスを吹き付けて急冷した。相の分離を目視で確認した後、各相成分をＩＣＰ−ＡＥＳを用いて分析した。各相の分析結果を表３に示す。表３からみて、これら三相は鉛直方向に上から順にネオジムを０．１４質量％程度含むＢ2Ｏ3相、黒緑色のネオジム、ジスプロシウム、プラセオジム等の希土類元素が富化されたＮｄ2Ｏ3−Ｂ2Ｏ3相、そして最下相の希土類元素をほとんど含んでいないＦｅ−Ｃ合金相であった。その結果、例１と同様に、鉛直方向に上から順にＢ2Ｏ3相、Ｎｄ2Ｏ3−Ｂ2Ｏ3相、及びＦｅ−Ｃ合金相の三相に分離したことが分かった。 <Example 2>
The same neodymium magnet as in Example 1 was subjected to the experiment in a lump state without being crushed. The neodymium magnet was subjected to Ni—Cu—Ni three-layer plating, but the surface was polished to remove the plating layer. A neodymium magnet sample (20 g) and B 2 O 3 (10 g) were inserted into a carbon crucible together with an Fe—C alloy (20 g) containing 4.3 mass% of C. The sample was heated and held in a carbon dioxide atmosphere at 1170 ° C. for 21.5 hours, and then quenched by blowing argon gas. After visually confirming phase separation, each phase component was analyzed using ICP-AES. Table 3 shows the analysis results of each phase. As seen from Table 3, these three phases are Nd 2 O enriched with rare earth elements such as B 2 O 3 phase containing about 0.14% by mass of neodymium in the vertical direction, black-green neodymium, dysprosium, praseodymium. 3 -B 2 O 3 phase and a rare earth element in the bottom phase was Fe-C alloy phase contains little. As a result, as in Example 1, it was found that the sample was separated into three phases of B 2 O 3 phase, Nd 2 O 3 —B 2 O 3 phase, and Fe—C alloy phase in order from the top in the vertical direction.

（単位：質量％） (Unit: mass%)

例２において、Ｂ2Ｏ3相中の希土類元素の総質量に対する希土類富化相（Nd2O3-B2O3相）中の希土類元素の総質量の比は２５４．８であり、Ｆｅ相（Fe-C合金相）中の希土類元素の総質量に対する希土類富化相中の希土類元素の総質量の比は１５２８．８倍であった。 In Example 2, the total weight ratio of rare earth elements in the rare earth-rich phase with respect to the total mass (Nd 2 O 3 -B 2 O 3 phases) of rare earth elements B 2 O 3 phase is 254.8, Fe The ratio of the total mass of the rare earth element in the rare earth-enriched phase to the total mass of the rare earth element in the phase (Fe—C alloy phase) was 1528.8 times.

＜例３＞
例１と同様のネオジム磁石を鉄乳鉢によって粉砕し実験に供した。ネオジム磁石にはＮｉ−Ｃｕ−Ｎｉの三層めっきが施されていたが、表面を研磨してめっき層を除去した。ネオジム磁石試料（５ｇ）及びＢ2Ｏ3（１０ｇ）を炭素るつぼへ挿入した。試料を１３５０℃で２時間、次いで１１７０℃で１時間、二酸化炭素雰囲気中で加熱保持した後、アルゴンガスを吹き付けて急冷した。相の分離を目視で確認した後、各相成分をＩＣＰ−ＡＥＳを用いて分析した。結果を表４に示す。 <Example 3>
The same neodymium magnet as in Example 1 was crushed with an iron mortar and used for the experiment. The neodymium magnet was subjected to Ni—Cu—Ni three-layer plating, but the surface was polished to remove the plating layer. A neodymium magnet sample (5 g) and B 2 O 3 (10 g) were inserted into a carbon crucible. The sample was heated and held in a carbon dioxide atmosphere at 1350 ° C. for 2 hours and then at 1170 ° C. for 1 hour, and then quenched by blowing argon gas. After visually confirming phase separation, each phase component was analyzed using ICP-AES. The results are shown in Table 4.

（単位：質量％） (Unit: mass%)

表４より、例１と同様に、鉛直方向に上からＢ2Ｏ3相、Ｎｄ2Ｏ3−Ｂ2Ｏ3相、及びＦｅ−Ｃ合金相の三相に分離したことが分かる。溶解したネオジウム磁石を構成する合金が炭素るつぼ、または二酸化炭素中の炭素と反応し、Ｆｅ−Ｃ合金相を形成したと考えられる。Ｂ2Ｏ3相中の希土類元素の総質量に対する希土類富化相（Nd2O3-B2O3相）中の希土類元素の総質量の比は１１９．１であり、Ｆｅ相（Fe-C合金相）中の希土類元素の総質量に対する希土類富化相中の希土類元素の総質量の比は５３２．０であった。上記実験結果より、磁石中の希土類元素をＮｄ2Ｏ3−Ｂ2Ｏ3相へ濃縮することが可能であることが分かる。この結果から、銑鉄を添加しなくても加熱溶融温度を高めることで希土類元素を濃縮可能であることが分かる。 From Table 4, it can be seen that, similarly to Example 1, it was separated from the top in the vertical direction into three phases of B 2 O 3 phase, Nd 2 O 3 —B 2 O 3 phase, and Fe—C alloy phase. It is considered that the alloy constituting the melted neodymium magnet reacted with carbon crucible or carbon in carbon dioxide to form an Fe-C alloy phase. The total weight ratio of rare earth elements in the rare earth-rich phase with respect to the total mass (Nd 2 O 3 -B 2 O 3 phases) of rare earth elements B 2 O 3 phase is 119.1, Fe phase (Fe- The ratio of the total mass of the rare earth elements in the rare earth-enriched phase to the total mass of the rare earth elements in the (C alloy phase) was 532.0. From the above experimental results, it can be seen that the rare earth element in the magnet can be concentrated to the Nd 2 O 3 —B 2 O 3 phase. From this result, it can be seen that the rare earth element can be concentrated by increasing the heating and melting temperature without adding pig iron.

＜例４＞
例１と同様のネオジム磁石を鉄乳鉢によって粉砕し実験に供した。ネオジム磁石にはＮｉ−Ｃｕ−Ｎｉの三層めっきが施されていたが、表面を研磨してめっき層を除去した。ネオジム磁石試料（５ｇ）及びＢ2Ｏ3（１０ｇ）を炭素るつぼへ挿入した。試料を１４５０℃で３時間、二酸化炭素雰囲気中で加熱保持した後、アルゴンガスを吹き付けて急冷した。相の分離を目視で確認した後、各相成分をＩＣＰ−ＡＥＳを用いて分析した。 <Example 4>
The same neodymium magnet as in Example 1 was crushed with an iron mortar and used for the experiment. The neodymium magnet was subjected to Ni—Cu—Ni three-layer plating, but the surface was polished to remove the plating layer. A neodymium magnet sample (5 g) and B 2 O 3 (10 g) were inserted into a carbon crucible. The sample was heated and held at 1450 ° C. for 3 hours in a carbon dioxide atmosphere, and then quenched by blowing argon gas. After visually confirming phase separation, each phase component was analyzed using ICP-AES.

その結果、例１と同様に、鉛直方向に上からＢ2Ｏ3相、Ｎｄ2Ｏ3−Ｂ2Ｏ3相、及びＦｅ−Ｃ合金相の三相に分離したことが分かった。表５に各相の分析結果を示す。しかしながら、例１と比較して、Ｆｅ−Ｃ合金相のＮｄ、Ｄｙ及びＰｒ濃度が上昇した。 As a result, in the same manner as in Example 1, it was found that the three phases of the B 2 O 3 phase, the Nd 2 O 3 —B 2 O 3 phase, and the Fe—C alloy phase were separated from the top in the vertical direction. Table 5 shows the analysis results of each phase. However, compared with Example 1, the Nd, Dy, and Pr concentrations of the Fe—C alloy phase increased.

（単位：質量％） (Unit: mass%)

表５より、Ｂ2Ｏ3相中の希土類元素の総質量に対する希土類富化相（Nd2O3-B2O3相）中の希土類元素の総質量の比は３４．５であり、Ｆｅ相（Fe-C合金相）中の希土類元素の総質量に対する希土類富化相中の希土類元素の総質量の比は６３．６であった。上記実験結果より、磁石中の希土類元素をＮｄ2Ｏ3−Ｂ2Ｏ3相へ濃縮することが可能であることが分かる。但し、本実施例では加熱温度が高く、Ｆｅ相に希土類元素が多く分配されたため、Ｆｅ相（Fe-C合金相）中の希土類元素の総質量に対する希土類富化相中の希土類元素の総質量の比が、例１〜例３に比べて低かった。 From Table 5, the total weight ratio of rare earth elements in the rare earth-rich phase with respect to the total mass (Nd 2 O 3 -B 2 O 3 phases) of rare earth elements B 2 O 3 phase is 34.5, Fe The ratio of the total mass of the rare earth element in the rare earth-enriched phase to the total mass of the rare earth element in the phase (Fe—C alloy phase) was 63.6. From the above experimental results, it can be seen that the rare earth element in the magnet can be concentrated to the Nd 2 O 3 —B 2 O 3 phase. However, in this example, since the heating temperature was high and a large amount of rare earth elements were distributed in the Fe phase, the total mass of rare earth elements in the rare earth-enriched phase relative to the total mass of rare earth elements in the Fe phase (Fe-C alloy phase) The ratio of was lower than those of Examples 1 to 3.

Claims (10)

希土類元素含有物質をＢ2Ｏ3の共存下で加熱溶融し、Ｂ2Ｏ3相と、Ｂ2Ｏ3相よりも下方にＢ2Ｏ3相よりも希土類元素が富化された相とを形成する工程１を含む希土類元素含有物質からの希土類元素濃縮方法。 The rare earth element-containing material is heated and melted in the presence of B 2 O 3, and B 2 O 3 phase, B 2 O 3 rare earth elements than B 2 O 3 phase below the phase and phase-enriched A method for concentrating rare earth elements from a rare earth-containing material, comprising the step 1 of forming. 工程１は、１１５０〜１６００℃で１０〜３６０分保持した後、冷却することを含む請求項１に記載の方法。   The method according to claim 1, wherein step 1 includes holding at 1150 to 1600 ° C. for 10 to 360 minutes and then cooling. 工程１を融点降下剤の共存下で行う請求項１又は２に記載の方法。   The method according to claim 1 or 2, wherein step 1 is carried out in the presence of a melting point depressant. 融点降下剤が炭素である請求項３に記載の方法。   The method of claim 3 wherein the melting point depressant is carbon. 炭素の供給源がＦｅ−Ｃ合金である請求項４に記載の方法。   The method of claim 4, wherein the source of carbon is an Fe-C alloy. 工程１を酸化剤の共存下で行う請求項１〜５の何れか一項に記載の方法。   The method as described in any one of Claims 1-5 which performs the process 1 in coexistence of an oxidizing agent. 酸化剤が酸化鉄である請求項６に記載の方法。   The method according to claim 6, wherein the oxidizing agent is iron oxide. Ｂ2Ｏ3相中の希土類元素の総質量に対する前記希土類元素が富化された相中の希土類元素の総質量の比が１０以上である請求項１〜７の何れか一項に記載の方法。 The method according to any one of claims 1 to 7 wherein the rare earth element to the total weight is 10 or more the ratio of the total mass of the rare earth elements in phase enriched in rare earth elements B 2 O 3 phase . 希土類元素にＮｄ、Ｄｙ及びＰｒから選択される少なくとも一種が含まれる請求項１〜８の何れか一項に記載の方法。   The method according to claim 1, wherein the rare earth element includes at least one selected from Nd, Dy, and Pr. 希土類元素含有物質は希土類磁石を原料とする請求項１〜９の何れか一項に記載の方法。   The method according to any one of claims 1 to 9, wherein the rare earth element-containing substance is a rare earth magnet.
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