JP6841082B2

JP6841082B2 - How to prepare a rare earth element solution

Info

Publication number: JP6841082B2
Application number: JP2017034201A
Authority: JP
Inventors: 星　裕之; 裕之星
Original assignee: Hitachi Metals Ltd
Current assignee: Hitachi Metals Ltd
Priority date: 2017-02-24
Filing date: 2017-02-24
Publication date: 2021-03-10
Anticipated expiration: 2037-02-24
Also published as: JP2018141181A

Description

本発明は、例えば、Ｒ−Ｆｅ−Ｂ系永久磁石（Ｒは希土類元素）などの軽希土類元素と重希土類元素を含む処理対象物から、溶媒抽出法によって両者を分離する際に有用な、希土類元素溶液を調製する方法に関する。 The present invention is useful for separating a light rare earth element such as an R-Fe-B permanent magnet (R is a rare earth element) and a treatment object containing a heavy rare earth element by a solvent extraction method. It relates to a method of preparing an elemental solution.

Ｒ−Ｆｅ−Ｂ系永久磁石は、高い磁気特性を有していることから、今日様々な分野で使用されていることは周知の通りである。このような背景のもと、Ｒ−Ｆｅ−Ｂ系永久磁石の生産工場では、日々、大量の磁石が生産されているが、磁石の生産量の増大に伴い、製造工程中に加工不良物などとして排出される磁石スクラップや、切削屑や研削屑などとして排出される磁石加工屑などの量も増加している。とりわけ情報機器の軽量化や小型化によってそこで使用される磁石も小型化していることから、加工代比率が大きくなることで、製造歩留まりが年々低下する傾向にある。従って、製造工程中に排出される磁石スクラップや磁石加工屑などを廃棄せず、そこに含まれる金属元素、特に希土類元素をいかに回収して再利用するかが今後の重要な技術課題となっている。また、Ｒ−Ｆｅ−Ｂ系永久磁石を使用した電化製品などから循環資源として希土類元素をいかに回収して再利用するかについても同様である。本発明者は、これまでこの技術課題に対して精力的に取り組んできており、その研究成果として、Ｒ−Ｆｅ−Ｂ系永久磁石などの希土類元素と鉄族元素を含む処理対象物から希土類元素を回収する方法として、処理対象物に対して酸化処理を行った後、処理環境を炭素の存在下に移し、１１５０℃以上の温度で熱処理することで、希土類元素を酸化物として鉄族元素から分離して回収する方法を特許文献１において提案している。 It is well known that R-Fe-B permanent magnets are used in various fields today because they have high magnetic properties. Against this background, R-Fe-B permanent magnet production plants produce a large amount of magnets every day, but with the increase in magnet production, defective products are produced during the manufacturing process. The amount of magnet scraps discharged as magnet scraps and magnet processing scraps discharged as cutting scraps and grinding scraps is also increasing. In particular, as information devices are made lighter and smaller, the magnets used there are also becoming smaller, so the manufacturing yield tends to decrease year by year as the processing allowance ratio increases. Therefore, it will be an important technical issue in the future how to recover and reuse the metal elements contained therein, especially rare earth elements, without discarding the magnet scraps and magnet processing scraps discharged during the manufacturing process. There is. The same applies to how rare earth elements are recovered and reused as recycled resources from electrical appliances using R-Fe-B permanent magnets. The present inventor has been energetically tackling this technical problem, and as a result of the research, rare earth elements such as R-Fe-B-based permanent magnets and rare earth elements from processed objects containing iron group elements. As a method of recovering, the treatment target is subjected to oxidation treatment, the treatment environment is moved to the presence of carbon, and heat treatment is performed at a temperature of 1150 ° C. or higher to use rare earth elements as oxides from iron group elements. Patent Document 1 proposes a method for separating and recovering.

本発明者が特許文献１において提案した方法は、低コストと簡易さが要求されるリサイクルシステムとして優れたものであるが、処理対象物が例えばＲ−Ｆｅ−Ｂ系永久磁石の場合、鉄族元素から分離して回収された希土類元素の酸化物は、ＮｄやＰｒなどの軽希土類元素とＤｙなどの重希土類元素の複合酸化物ないし酸化物の混合物である。従って、希土類元素と鉄族元素を含む処理対象物から希土類元素を回収する優れた方法が特許文献１によって提供された今、次なる課題は、軽希土類元素と重希土類元素をいかに分離するかという点にある。 The method proposed by the present inventor in Patent Document 1 is excellent as a recycling system that requires low cost and simplicity. However, when the object to be processed is, for example, an R-Fe-B permanent magnet, the iron group The oxide of a rare earth element separated from the element and recovered is a mixture of a composite oxide or oxide of a light rare earth element such as Nd or Pr and a heavy rare earth element such as Dy. Therefore, now that Patent Document 1 has provided an excellent method for recovering rare earth elements from a treated object containing rare earth elements and iron group elements, the next issue is how to separate light rare earth elements and heavy rare earth elements. At the point.

軽希土類元素と重希土類元素を分離する方法として知られている一般的なものは、溶媒抽出法によるものである（例えば特許文献２）。現在のところ、溶媒抽出法は、希土類元素の分離や精製についての主流的な技術として位置付けられている。しかしながら、溶媒抽出法は、抽出剤としての２−エチルヘキシルホスホン酸モノ−２−エチルヘキシルエステルなどの有機リン化合物や、ケロシンなどの引火性の高い有機溶媒を用いて抽出操作を複数段にわたって繰り返す必要があるので、それぞれの使用量が多く、また、装置が大型のものとなるため、環境保全上や安全上の観点から抽出剤や有機溶媒の使用量の低減化が求められているとともに、装置の小型化が求められている。加えて、溶媒抽出法は、処理対象物に含まれる軽希土類元素と重希土類元素の含量比に応じた処理条件を設定する必要があるため、処理対象物が例えば含まれる軽希土類元素と重希土類元素の含量比が様々な磁石加工屑の混合物であって処理対象物における両者の含量比が不明の場合、その都度、処理対象物を分析して両者の含量比を求めてから処理条件を設定したり、両者の含量比が既存の処理条件に適合するものになるように各々の濃度を調整したりしなければならないという工程上の作業負担がある。 A common method known as a method for separating light rare earth elements and heavy rare earth elements is a solvent extraction method (for example, Patent Document 2). At present, the solvent extraction method is positioned as the mainstream technique for the separation and purification of rare earth elements. However, in the solvent extraction method, it is necessary to repeat the extraction operation in multiple stages using an organic phosphorus compound such as 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as an extractant or a highly flammable organic solvent such as kerosene. Therefore, the amount of each used is large, and the equipment is large, so it is required to reduce the amount of extractants and organic solvents used from the viewpoint of environmental protection and safety, and the equipment is also used. Miniaturization is required. In addition, in the solvent extraction method, it is necessary to set the treatment conditions according to the content ratio of the light rare earth element and the heavy rare earth element contained in the object to be treated. When the content ratio of both elements in the treatment target is unknown in a mixture of magnet processing scraps with various element content ratios, the treatment target is analyzed each time to obtain the content ratio of both, and then the treatment conditions are set. However, there is a work load in the process that each concentration must be adjusted so that the content ratio of both is suitable for the existing treatment conditions.

国際公開第２０１３／０１８７１０号International Publication No. 2013/018710 特開平２−８０５３０号公報Japanese Unexamined Patent Publication No. 2-80530

そこで本発明は、例えば溶媒抽出法によって軽希土類元素と重希土類元素を含む処理対象物から両者を分離するに際し、抽出剤や有機溶媒の使用量の低減化や装置の小型化を可能にしたり、処理対象物に含まれる軽希土類元素と重希土類元素の含量比の分析などの工程上の作業負担の軽減化を可能にしたりする、希土類元素溶液を調製する方法を提供することを目的とする。 Therefore, the present invention makes it possible to reduce the amount of extractant and organic solvent used and to reduce the size of the apparatus when separating the two from the object to be treated containing the light rare earth element and the heavy rare earth element, for example, by the solvent extraction method. It is an object of the present invention to provide a method for preparing a rare earth element solution, which makes it possible to reduce the work load in the process such as analysis of the content ratio of the light rare earth element and the heavy rare earth element contained in the object to be treated.

本発明者は上記の点に鑑みて鋭意検討を重ねた結果、軽希土類元素と重希土類元素を含む処理対象物から得られる両者の複合酸化物ないし酸化物の混合物を塩酸や硝酸に溶解した後、沈殿剤を加えて得られる沈殿物を焼成し、得られた焼成物の所定量を、所定濃度の塩酸などの無機酸と酢酸などの有機酸からなる混合酸に溶解することで、軽希土類元素リッチな溶液と、重希土類元素リッチな残渣を得ることができること、軽希土類元素リッチな溶液に含まれる軽希土類元素と重希土類元素の含量比は、含まれる軽希土類元素と重希土類元素の含量比にバラツキがある処理対象物から得られたものであっても、一定の範囲に収束したものになること、この含量比は、塩酸などの無機酸に対する酢酸などの有機酸の混合量を変えることで、調整することができることを見出した。 As a result of diligent studies in view of the above points, the present inventor has dissolved a composite oxide or a mixture of oxides of both light rare earth elements and heavy rare earth elements obtained from a treatment object in hydrochloric acid or nitric acid. , The precipitate obtained by adding a precipitant is calcined, and a predetermined amount of the obtained calcined product is dissolved in a mixed acid composed of an inorganic acid such as hydrochloric acid and an organic acid such as acetic acid at a predetermined concentration to obtain a light rare earth element. It is possible to obtain an element-rich solution and a heavy rare earth element-rich residue, and the content ratio of the light rare earth element and the heavy rare earth element contained in the light rare earth element rich solution is the content of the light rare earth element and the heavy rare earth element contained. Even if it is obtained from a treatment object having a variation in ratio, it will be converged within a certain range, and this content ratio changes the mixing amount of organic acid such as acetic acid to inorganic acid such as nitric acid. I found that it can be adjusted.

上記の知見に基づいてなされた本発明の希土類元素溶液を調製する方法は、請求項１記載の通り、
（１）軽希土類元素と重希土類元素を含む処理対象物から両者の複合酸化物ないし酸化物の混合物を得る工程
（２）得られた軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を、塩酸および／または硝酸に溶解する工程
（３）得られた溶液に沈殿剤を加えて沈殿物を得る工程
（４）得られた沈殿物を焼成する工程
（５）得られた焼成物を、濃度が０．７ｍｏｌ／Ｌ以上の、塩酸および硝酸から選ばれる少なくとも１つの無機酸と、酢酸、クエン酸、乳酸、アセチルアセトン酸、α−ヒドロキシイソ酪酸から選ばれる少なくとも１つの有機酸からなる混合酸に、溶解上限量の１．５倍以上添加して、軽希土類元素リッチな溶液と重希土類元素リッチな残渣を得る工程（混合酸の濃度は無機酸の濃度と有機酸の濃度の合計濃度）
（６）得られた溶液を残渣から分離する工程
を少なくとも含んでなることを特徴とする（ここで「リッチ」なる用語は該当する希土類元素の他方の希土類元素に対する含量比が処理対象物における含量比よりも大きいことを意味する）。
また、請求項２記載の方法は、請求項１記載の方法において、沈殿剤としてシュウ酸、酢酸、炭酸の金属塩から選ばれる少なくとも１つを用いることを特徴とする。
また、請求項３記載の方法は、請求項１記載の方法において、処理対象物がＲ−Ｆｅ−Ｂ系永久磁石であることを特徴とする。
また、請求項４記載の方法は、請求項１記載の方法において、処理対象物に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量／軽希土類元素の含量）が０．０５〜０．５０であることを特徴とする。
また、請求項５記載の方法は、請求項１記載の方法において、軽希土類元素リッチな溶液に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量／軽希土類元素の含量）が０．０２〜０．１０であり、かつ、処理対象物に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量／軽希土類元素の含量）よりも０．０１以上小さいことを特徴とする。 The method for preparing the rare earth element solution of the present invention based on the above findings is as described in claim 1.
(1) Step of obtaining a composite oxide or a mixture of oxides of both from a treatment target containing a light rare earth element and a heavy rare earth element (2) A composite oxide or oxide of the obtained light rare earth element and a heavy rare earth element Step of dissolving the mixture in hydrochloric acid and / or nitric acid (3) Step of adding a precipitant to the obtained solution to obtain a precipitate (4) Step of firing the obtained precipitate (5) Step of calcining the obtained precipitate Consists of at least one inorganic acid selected from hydrochloric acid and nitric acid having a concentration of 0.7 mol / L or more, and at least one organic acid selected from acetic acid, citric acid, lactic acid, acetylacetate acid, and α-hydroxyisobutyric acid. A step of adding 1.5 times or more of the upper limit of dissolution to a mixed acid to obtain a solution rich in light rare earth elements and a residue rich in heavy rare earth elements (the concentration of mixed acid is the sum of the concentration of inorganic acid and the concentration of organic acid). concentration)
(6) It is characterized by including at least a step of separating the obtained solution from the residue (here, the term "rich" means that the content ratio of the corresponding rare earth element to the other rare earth element is the content in the object to be treated. Means greater than the ratio).
The method according to claim 2 is characterized in that at least one selected from metal salts of oxalic acid, acetic acid, and carbonic acid is used as a precipitating agent in the method according to claim 1.
Further, the method according to claim 3 is characterized in that, in the method according to claim 1, the object to be processed is an R-Fe-B-based permanent magnet.
Further, in the method according to claim 4, in the method according to claim 1, the content ratio of the light rare earth element to the heavy rare earth element (content of the heavy rare earth element / content of the light rare earth element) contained in the object to be treated is 0. It is characterized by being 05 to 0.50.
The method according to claim 5 is the method according to claim 1, wherein the content ratio of the light rare earth element to the heavy rare earth element contained in the solution rich in the light rare earth element (content of the heavy rare earth element / content of the light rare earth element). Is 0.02 to 0.10. And is 0.01 or more smaller than the content ratio of the light rare earth element and the heavy rare earth element (content of the heavy rare earth element / content of the light rare earth element) contained in the object to be treated. It is characterized by.

本発明によれば、例えば溶媒抽出法によって軽希土類元素と重希土類元素を含む処理対象物から両者を分離するに際し、抽出剤や有機溶媒の使用量の低減化や装置の小型化を可能にしたり、処理対象物に含まれる軽希土類元素と重希土類元素の含量比の分析などの工程上の作業負担の軽減化を可能にしたりする、希土類元素溶液を調製する方法を提供することができる。 According to the present invention, for example, when separating a light rare earth element and a heavy rare earth element from a processing object by a solvent extraction method, it is possible to reduce the amount of an extractant or an organic solvent used and to reduce the size of the apparatus. It is possible to provide a method for preparing a rare earth element solution, which makes it possible to reduce the work load in the process such as analysis of the content ratio of the light rare earth element and the heavy rare earth element contained in the object to be treated.

実施例１における、塩酸に対する酢酸の混合量と、酸溶液由来の焼成物に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量Ｗ_ＨＲ／軽希土類元素の含量Ｗ_ＬＲ）の関係を示すグラフである。The mixing amount of acetic acid with respect to hydrochloric acid in Example 1 and the content ratio of light rare earth element and heavy rare earth element contained in the calcined product derived from the acid solution (content of heavy rare earth element _WHR / content of light rare earth element _WLR ). It is a graph which shows the relationship. 実施例２における、塩酸に対するクエン酸の混合量と、酸溶液由来の焼成物に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量Ｗ_ＨＲ／軽希土類元素の含量Ｗ_ＬＲ）の関係を示すグラフである。The mixing amount of citric acid with hydrochloric acid in Example 2 and the content ratio of light rare earth element and heavy rare earth element contained in the calcined product derived from the acid solution (content of heavy rare earth element _WHR / content of light rare earth element _WLR ). It is a graph which shows the relationship of.

本発明の希土類元素溶液を調製する方法は、
（１）軽希土類元素と重希土類元素を含む処理対象物から両者の複合酸化物ないし酸化物の混合物を得る工程
（２）得られた軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を、塩酸および／または硝酸に溶解する工程
（３）得られた溶液に沈殿剤を加えて沈殿物を得る工程
（４）得られた沈殿物を焼成する工程
（５）得られた焼成物を、濃度が０．７ｍｏｌ／Ｌ以上の、塩酸および硝酸から選ばれる少なくとも１つの無機酸と、酢酸、クエン酸、乳酸、アセチルアセトン酸、α−ヒドロキシイソ酪酸から選ばれる少なくとも１つの有機酸からなる混合酸に、溶解上限量の１．５倍以上添加して、軽希土類元素リッチな溶液と重希土類元素リッチな残渣を得る工程（混合酸の濃度は無機酸の濃度と有機酸の濃度の合計濃度）
（６）得られた溶液を残渣から分離する工程
を少なくとも含んでなることを特徴とするものである（ここで「リッチ」なる用語は該当する希土類元素の他方の希土類元素に対する含量比が処理対象物における含量比よりも大きいことを意味する）。以下、本発明の方法における工程を順次説明する。 The method for preparing the rare earth element solution of the present invention is
(1) Step of obtaining a composite oxide or a mixture of oxides of both from a treatment target containing a light rare earth element and a heavy rare earth element (2) A composite oxide or oxide of the obtained light rare earth element and a heavy rare earth element Step of dissolving the mixture in hydrochloric acid and / or nitric acid (3) Step of adding a precipitant to the obtained solution to obtain a precipitate (4) Step of firing the obtained precipitate (5) Step of calcining the obtained precipitate Consists of at least one inorganic acid selected from hydrochloric acid and nitric acid having a concentration of 0.7 mol / L or more, and at least one organic acid selected from acetic acid, citric acid, lactic acid, acetylacetate acid, and α-hydroxyisobutyric acid. A step of adding 1.5 times or more of the upper limit of dissolution to a mixed acid to obtain a solution rich in light rare earth elements and a residue rich in heavy rare earth elements (the concentration of mixed acid is the sum of the concentration of inorganic acid and the concentration of organic acid). concentration)
(6) It is characterized by including at least a step of separating the obtained solution from the residue (here, the term "rich" means the content ratio of the corresponding rare earth element to the other rare earth element to be treated. It means that it is larger than the content ratio in the thing). Hereinafter, the steps in the method of the present invention will be sequentially described.

（１）軽希土類元素と重希土類元素を含む処理対象物から両者の複合酸化物ないし酸化物の混合物を得る工程
まず、本発明の方法を適用することができる軽希土類元素と重希土類元素を含む処理対象物は、ＮｄやＰｒなどの軽希土類元素とＤｙやＴｂなどの重希土類元素を含むものであれば特段の制限はなく、軽希土類元素と重希土類元素に加えてその他の元素としてＦｅ，Ｃｏ，Ｎｉなどの鉄族元素やホウ素などを含んでいてもよい。具体的には、例えばＲ−Ｆｅ−Ｂ系永久磁石などが挙げられる。軽希土類元素と重希土類元素を含む処理対象物から両者の複合酸化物ないし酸化物の混合物を得る方法は、自体公知の方法であってよく、例えば、特許文献１に記載の、希土類元素と鉄族元素を含む処理対象物に対して酸化処理を行った後、処理環境を炭素の存在下に移し、１１５０℃以上の温度で熱処理することで、希土類元素を酸化物として鉄族元素から分離して回収する方法を好適に採用することができる。軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物の、軽希土類元素の含量と重希土類元素の含量の合計は、７０ｍａｓｓ％以上が望ましく、７５ｍａｓｓ％以上がより望ましい。軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物は、鉄族元素やホウ素などを含んでいてもよいが、これらの含量は、それぞれ５．０ｍａｓｓ％以下が望ましく、２．５ｍａｓｓ％以下がより望ましい。 (1) Step of obtaining a composite oxide or a mixture of oxides of both from a treatment target containing a light rare earth element and a heavy rare earth element First, the light rare earth element and the heavy rare earth element to which the method of the present invention can be applied are included. There are no particular restrictions as long as the object to be treated contains light rare earth elements such as Nd and Pr and heavy rare earth elements such as Dy and Tb, and Fe, as other elements in addition to the light rare earth elements and heavy rare earth elements, It may contain iron group elements such as Co and Ni and boron and the like. Specific examples thereof include R-Fe-B type permanent magnets. The method for obtaining a composite oxide or a mixture of oxides of both from a treatment object containing a light rare earth element and a heavy rare earth element may be a method known per se, for example, the rare earth element and iron described in Patent Document 1. After performing oxidation treatment on the object to be treated containing group elements, the treatment environment is moved to the presence of carbon and heat treatment is performed at a temperature of 1150 ° C. or higher to separate rare earth elements from iron group elements as oxides. The method of collecting the material can be preferably adopted. The total content of the light rare earth element and the content of the heavy rare earth element in the composite oxide or the mixture of the heavy rare earth element and the heavy rare earth element is preferably 70 mass% or more, and more preferably 75 mass% or more. The composite oxide or mixture of the light rare earth element and the heavy rare earth element may contain an iron group element, boron, etc., but the content thereof is preferably 5.0 mass% or less, and 2.5 mass%, respectively. The following are more desirable.

（２）得られた軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を、塩酸および／または硝酸に溶解する工程
この工程に用いる塩酸や硝酸は、先の工程で得られた軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を溶解することができる濃度や容量で用いることができる。具体的には、例えば、濃度が０．５ｍｏｌ／Ｌ以上の塩酸や硝酸を、軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物１ｇに対して１ｍＬ〜５０ｍＬの割合で用いればよい。用いる塩酸や硝酸の濃度の上限は、安全性などの点に鑑みれば例えば５．０ｍｏｌ／Ｌである。溶解温度は、例えば２０℃〜８５℃であってよい。溶解時間は、例えば１時間〜３日間であってよい。なお、軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物は、その溶解を効率的に行うために、粒径が１ｍｍ以下の粒状ないし粉末状に粉砕して塩酸や硝酸に溶解することが望ましい。粉砕は粒径が５００μｍ以下になるまで行うことがより望ましい。所望する粒径の軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物は、例えば篩を用いて分級することで得ることができる。 (2) Step of dissolving the obtained composite oxide or mixture of light rare earth element and heavy rare earth element in hydrochloric acid and / or nitric acid The hydrochloric acid and nitric acid used in this step are the light obtained in the previous step. It can be used at a concentration and volume capable of dissolving a composite oxide of a rare earth element and a heavy rare earth element or a mixture of oxides. Specifically, for example, hydrochloric acid or nitric acid having a concentration of 0.5 mol / L or more may be used at a ratio of 1 mL to 50 mL with respect to 1 g of a composite oxide or oxide mixture of a light rare earth element and a heavy rare earth element. .. The upper limit of the concentration of hydrochloric acid or nitric acid used is, for example, 5.0 mol / L in view of safety and the like. The melting temperature may be, for example, 20 ° C to 85 ° C. The dissolution time may be, for example, 1 hour to 3 days. In addition, in order to efficiently dissolve the composite oxide or oxide of the light rare earth element and the heavy rare earth element, it is pulverized into granules or powders having a particle size of 1 mm or less and dissolved in hydrochloric acid or nitric acid. Is desirable. It is more desirable to carry out pulverization until the particle size becomes 500 μm or less. A mixture of a composite oxide or oxide of a light rare earth element and a heavy rare earth element having a desired particle size can be obtained by classification using, for example, a sieve.

（３）得られた溶液に沈殿剤を加えて沈殿物を得る工程
この工程に用いることができる沈殿剤としては、例えばシュウ酸や酢酸や炭酸の金属塩（炭酸ナトリウムなど）が挙げられ、先の工程で塩酸や硝酸に溶解した軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を、軽希土類元素と重希土類元素のシュウ酸塩や酢酸塩や炭酸塩からなる沈殿物に変換する。シュウ酸や酢酸や炭酸の金属塩は、軽希土類元素と重希土類元素のシュウ酸塩や酢酸塩や炭酸塩からなる沈殿物を得ることができる量で用いることができる。具体的には、シュウ酸や酢酸や炭酸の金属塩は、先の工程で塩酸や硝酸に溶解した軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物１ｇに対して例えば０．８ｇ〜３．０ｇの割合で用いればよい。沈殿温度は、例えば２０℃〜８５℃であってよい。沈殿時間は、例えば１時間〜６時間であってよい。 (3) Step of adding a precipitant to the obtained solution to obtain a precipitate Examples of the precipitant that can be used in this step include metal salts of oxalic acid, acetic acid and carbonic acid (sodium carbonate, etc.). A mixture of a composite oxide or oxide of a light rare earth element and a heavy rare earth element dissolved in hydrochloric acid or nitric acid is converted into a precipitate consisting of a oxalate, an acetate or a carbonate of the light rare earth element and the heavy rare earth element. To do. The metal salts of oxalic acid, acetate and carbonic acid can be used in an amount capable of obtaining a precipitate composed of oxalates, acetates and carbonates of light rare earth elements and heavy rare earth elements. Specifically, the metal salts of oxalic acid, acetic acid, and carbonic acid are, for example, 0.8 g per 1 g of a composite oxide or oxide of a light rare earth element and a heavy rare earth element dissolved in hydrochloric acid or nitric acid in the previous step. It may be used in a ratio of ~ 3.0 g. The precipitation temperature may be, for example, 20 ° C to 85 ° C. The precipitation time may be, for example, 1 hour to 6 hours.

（４）得られた沈殿物を焼成する工程
次に、先の工程で得られた軽希土類元素と重希土類元素のシュウ酸塩や酢酸塩や炭酸塩からなる沈殿物を焼成し、軽希土類元素と重希土類元素のシュウ酸塩や酢酸塩や炭酸塩を再び複合酸化物ないし酸化物の混合物に変換する。軽希土類元素リッチな溶液と重希土類元素リッチな残渣を効果的に得るためには、沈殿物の焼成は、例えば大気雰囲気などの酸素が存在する雰囲気で５００℃〜１０００℃で行うことが望ましい。焼成温度は、６００℃〜９５０℃がより望ましく、７００℃〜９００℃がさらに望ましい。焼成時間は、例えば１時間〜６時間であってよい。 (4) Step of calcining the obtained precipitate Next, calcining the precipitate composed of oxalate, acetate and carbonate of the light rare earth element and the heavy rare earth element obtained in the previous step is carried out, and the light rare earth element is calcined. And the heavy rare earth elements oxalate, acetate and carbonate are converted again into a composite oxide or a mixture of oxides. In order to effectively obtain a light rare earth element-rich solution and a heavy rare earth element-rich residue, it is desirable that the precipitate is calcined at 500 ° C. to 1000 ° C. in an atmosphere in which oxygen is present, such as an atmospheric atmosphere. The firing temperature is more preferably 600 ° C. to 950 ° C., and even more preferably 700 ° C. to 900 ° C. The firing time may be, for example, 1 hour to 6 hours.

（５）得られた焼成物を、濃度が０．７ｍｏｌ／Ｌ以上の、塩酸および硝酸から選ばれる少なくとも１つの無機酸と、酢酸、クエン酸、乳酸、アセチルアセトン酸、α−ヒドロキシイソ酪酸から選ばれる少なくとも１つの有機酸からなる混合酸に、溶解上限量の１．５倍以上添加して、軽希土類元素リッチな溶液と重希土類元素リッチな残渣を得る工程（混合酸の濃度は無機酸の濃度と有機酸の濃度の合計濃度）
この工程は、本発明の方法において鍵となる工程である。肝要なのは、先の工程で得られた焼成物、即ち、軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を、塩酸および硝酸から選ばれる少なくとも１つの無機酸と、酢酸、クエン酸、乳酸、アセチルアセトン酸、α−ヒドロキシイソ酪酸から選ばれる少なくとも１つの有機酸からなる混合酸に溶けきらない量、即ち、溶解上限量よりも多い量で混合酸に添加しなければならないということと、混合酸は、所定の濃度（無機酸の濃度と有機酸の濃度の合計濃度）以上のものでなければならないということである。このように処理条件を設定することで、焼成物に含まれる軽希土類元素は混合酸に溶解しようとする一方で、重希土類元素は焼成物に残留しようとすることを本発明者は見出した。軽希土類元素と重希土類元素のこの性質を利用することで、軽希土類元素リッチな溶液と重希土類元素リッチな残渣を得ることができる。また、軽希土類元素リッチな溶液に含まれる軽希土類元素と重希土類元素の含量比は、含まれる軽希土類元素と重希土類元素の含量比にバラツキがある処理対象物から得られたものであっても、一定の範囲に収束したものになり、この含量比は、無機酸に対する有機酸の混合量を変えることで、調整することができる。混合酸への焼成物の添加量の下限を溶解上限量の１．５倍と規定するのは、１．５倍未満では、焼成物に含まれる重希土類元素が軽希土類元素とともに混合酸に溶解してしまいやすくなるからである。混合酸への焼成物の添加量を溶解上限量の１．０倍以下とすると、焼成物が混合酸に溶けきってしまうので、焼成物に含まれる軽希土類元素と重希土類元素の全量が混合酸に溶解する（結果として軽希土類元素リッチな溶液と重希土類元素リッチな残渣を得ることはできない）。混合酸への焼成物の添加量の上限は、例えば溶解上限量の４．０倍である。溶解上限量の４．０倍を超えると、焼成物に含まれる軽希土類元素の多くが混合酸に溶解しきれなくなることで、軽希土類元素が焼成物に残留しやすくなり、結果として軽希土類元素リッチな溶液と重希土類元素リッチな残渣を得にくくなる。軽希土類元素リッチな溶液と重希土類元素リッチな残渣を効果的に得るためには、混合酸への焼成物の添加量は、溶解上限量の１．８倍〜３．５倍が望ましく、２．０倍〜３．０倍がより望ましい。なお、混合酸に対する焼成物の溶解上限量は、用いる混合酸に焼成物を少量ずつ溶解することで実験的に求めることもできるし、計算で求めることもできる（例えば、焼成物に軽希土類元素と重希土類元素以外の金属元素が含まれていてもその量はごく僅かであるので、焼成物が軽希土類元素と重希土類元素のみからなると見做し、焼成物の組成に基づいて、用いる混合酸から供給される水素イオンのモル量（ｐＨの変動による供給量の変動はないものとする）と各希土類元素の価数から算出する。こうして算出される溶解上限量は厳密なものではないが、この工程を実施する上での支障はない）。用いる混合酸の濃度の下限を０．７ｍｏｌ／Ｌと規定するのは、０．７ｍｏｌ／Ｌ未満では、焼成物に含まれる軽希土類元素が重希土類元素に優先して溶解せずに、軽希土類元素とともに重希土類元素も溶解してしまいやすくなるからである。混合酸の濃度の下限は１．０ｍｏｌ／Ｌが望ましい。なお、混合酸の濃度の上限は、安全性などの点に鑑みれば、例えば５．０ｍｏｌ／Ｌである。無機酸に対する有機酸の混合量は、無機酸１ｍｏｌに対して有機酸０．０５ｍｏｌ〜０．５０ｍｏｌが望ましく、０．１０ｍｏｌ〜０．４０ｍｏｌがより望ましい。無機酸に対する有機酸の混合量が少なすぎても多すぎても、軽希土類元素リッチな溶液に含まれる軽希土類元素と重希土類元素の含量比を調整しにくくなる（その理由は必ずしも明確ではないが、有機酸として用いる酢酸、クエン酸、乳酸、アセチルアセトン酸、α−ヒドロキシイソ酪酸の、軽希土類元素と重希土類元素のそれぞれに対する錯体形成能の違いに基づくと考えられる）。焼成物を添加する混合酸の温度は、例えば２０℃〜８５℃であってよく、焼成物を添加した後、例えば１時間〜１０時間撹拌保持するのがよい。 (5) The obtained calcined product is selected from at least one inorganic acid selected from hydrochloric acid and nitric acid having a concentration of 0.7 mol / L or more, acetic acid, citric acid, lactic acid, acetylacetoneic acid, and α-hydroxyisobutyric acid. A step of adding 1.5 times or more of the upper limit of dissolution to a mixed acid consisting of at least one organic acid to obtain a solution rich in light rare earth elements and a residue rich in heavy rare earth elements (the concentration of the mixed acid is that of an inorganic acid. Total concentration of concentration and concentration of organic acid)
This step is a key step in the method of the present invention. What is important is that the calcined product obtained in the previous step, that is, a mixture of a composite oxide or oxide of a light rare earth element and a heavy rare earth element, is mixed with at least one inorganic acid selected from hydrochloric acid and nitric acid, and acetic acid and citric acid. , Lactic acid, acetylacetoneic acid, α-hydroxyisobutyric acid, which must be added to the mixed acid in an amount insoluble in the mixed acid consisting of at least one organic acid, that is, an amount larger than the upper limit of dissolution. , The mixed acid must be greater than or equal to a predetermined concentration (the sum of the concentration of the inorganic acid and the concentration of the organic acid). The present inventor has found that by setting the treatment conditions in this way, the light rare earth elements contained in the calcined product tend to dissolve in the mixed acid, while the heavy rare earth elements tend to remain in the calcined product. By utilizing this property of the light rare earth element and the heavy rare earth element, a solution rich in the light rare earth element and a residue rich in the heavy rare earth element can be obtained. In addition, the content ratios of light rare earth elements and heavy rare earth elements contained in the light rare earth element-rich solution were obtained from the objects to be treated in which the content ratios of the light rare earth elements and heavy rare earth elements contained varied. However, it converges to a certain range, and this content ratio can be adjusted by changing the mixing amount of the organic acid with respect to the inorganic acid. The lower limit of the amount of calcined product added to the mixed acid is defined as 1.5 times the upper limit of dissolution. If it is less than 1.5 times, the heavy rare earth elements contained in the calcined product are dissolved in the mixed acid together with the light rare earth elements. This is because it is easy to do. If the amount of the calcined product added to the mixed acid is 1.0 times or less of the upper limit of dissolution, the calcined product will be completely dissolved in the mixed acid, so that the total amount of the light rare earth elements and the heavy rare earth elements contained in the calcined product will be mixed. Soluble in acid (resulting in no light rare earth element rich solution and heavy rare earth element rich residue). The upper limit of the amount of the calcined product added to the mixed acid is, for example, 4.0 times the upper limit of dissolution. If it exceeds 4.0 times the upper limit of dissolution, most of the light rare earth elements contained in the fired product cannot be completely dissolved in the mixed acid, so that the light rare earth elements tend to remain in the fired product, and as a result, the light rare earth elements. It becomes difficult to obtain a rich solution and a heavy rare earth element-rich residue. In order to effectively obtain a light rare earth element-rich solution and a heavy rare earth element-rich residue, the amount of the calcined product added to the mixed acid is preferably 1.8 to 3.5 times the upper limit of dissolution. 0.0 to 3.0 times is more desirable. The upper limit of dissolution of the calcined product with respect to the mixed acid can be obtained experimentally or by calculation by dissolving the calcined product in the mixed acid to be used little by little (for example, a light rare earth element in the calcined product). Even if a metal element other than the heavy rare earth element is contained, the amount is very small. Therefore, it is considered that the calcined product consists only of the light rare earth element and the heavy rare earth element, and the mixture to be used is used based on the composition of the calcined product. It is calculated from the molar amount of hydrogen ions supplied from the acid (assuming that the supply amount does not fluctuate due to fluctuations in pH) and the valence of each rare earth element. , There is no hindrance in carrying out this process). The lower limit of the concentration of the mixed acid to be used is defined as 0.7 mol / L. If the concentration is less than 0.7 mol / L, the light rare earth elements contained in the calcined product do not dissolve in preference to the heavy rare earth elements, and the light rare earth elements. This is because heavy rare earth elements are likely to dissolve together with the elements. The lower limit of the concentration of the mixed acid is preferably 1.0 mol / L. The upper limit of the concentration of the mixed acid is, for example, 5.0 mol / L in view of safety and the like. The amount of the organic acid mixed with the inorganic acid is preferably 0.05 mol to 0.50 mol, more preferably 0.10 mol to 0.40 mol, with respect to 1 mol of the inorganic acid. If the amount of organic acid mixed with inorganic acid is too small or too large, it will be difficult to adjust the content ratio of light rare earth element and heavy rare earth element contained in the light rare earth element rich solution (the reason is not always clear). However, it is considered to be based on the difference in complex-forming ability of acetic acid, citric acid, lactic acid, acetylacetoneic acid, and α-hydroxyisobutyric acid used as organic acids for each of light rare earth elements and heavy rare earth elements). The temperature of the mixed acid to which the calcined product is added may be, for example, 20 ° C. to 85 ° C., and after adding the calcined product, it is preferably kept stirred for, for example, 1 hour to 10 hours.

（６）得られた溶液を残渣から分離する工程
先の工程で得られる溶液には軽希土類元素が多く含まれ（即ち軽希土類元素の重希土類元素に対する含量比が処理対象物における含量比よりも大きい）、残渣には重希土類元素が多く含まれる（即ち重希土類元素の軽希土類元素に対する含量比が処理対象物における含量比よりも大きい）。従って、溶液を残渣から例えば濾過により分離することで、軽希土類元素リッチな溶液を本発明の希土類元素溶液として得ることができる。重希土類元素リッチな残渣から分離された軽希土類元素リッチな溶液、即ち、本発明の希土類元素溶液は、自体公知の方法によって溶媒抽出法に付すことで、溶液に含まれる軽希土類元素と重希土類元素を分離することができる。この際、軽希土類元素リッチな溶液には、処理対象物よりも軽希土類元素が多く含まれているので、処理対象物それ自体を溶媒抽出法に付して軽希土類元素と重希土類元素を分離する場合よりも、抽出操作に必要な段数を少なくすることができるため、抽出剤や有機溶媒の使用量の低減化や装置の小型化が可能になる。また、処理対象物に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量／軽希土類元素の含量）が、例えば０．０５〜０．５０の範囲でバラツキがあっても、軽希土類元素リッチな溶液に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量／軽希土類元素の含量）は、例えば０．０２〜０．１０の範囲に収束したものになるということは特筆すべき点である（但し処理対象物に含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量／軽希土類元素の含量）よりも０．０１以上小さい）。従って、含まれる軽希土類元素と重希土類元素の含量比（重希土類元素の含量／軽希土類元素の含量）が、例えば０．０５〜０．５０の範囲の処理対象物であれば（Ｒ−Ｆｅ−Ｂ系永久磁石における両者の含量比はこの範囲にある）、その都度、処理対象物を分析して両者の含量比を求めなくても、収束した含量比に適合する処理条件で溶液に含まれる軽希土類元素と重希土類元素を分離することができる。また、軽希土類元素リッチな溶液に含まれる軽希土類元素と重希土類元素の含量比は、無機酸に対する有機酸の混合量を変えることで調整することができるので、両者を分離するための処理条件を設定する際の自由度が高い。なお、軽希土類元素リッチな溶液から分離された重希土類元素リッチな残渣に対して例えば（２）〜（６）の工程を実施することで、残渣に含まれる軽希土類元素の量を低減すること（重希土類元素の軽希土類元素に対する含量比をより大きくすること）ができる。この場合、重希土類元素リッチな残渣から分離された軽希土類元素リッチな溶液は、本発明の希土類元素溶液として、自体公知の方法によって溶媒抽出法に付すことで、溶液に含まれる軽希土類元素と重希土類元素を分離することができることは、上記の通りである。 (6) Step of separating the obtained solution from the residue The solution obtained in the previous step contains a large amount of light rare earth elements (that is, the content ratio of the light rare earth element to the heavy rare earth element is larger than the content ratio in the object to be treated. (Large), the residue contains a large amount of heavy rare earth elements (that is, the content ratio of heavy rare earth elements to light rare earth elements is larger than the content ratio in the object to be treated). Therefore, by separating the solution from the residue by, for example, filtration, a light rare earth element-rich solution can be obtained as the rare earth element solution of the present invention. Light rare earth element-rich solution separated from heavy rare earth element-rich residue, that is, the rare earth element solution of the present invention is subjected to a solvent extraction method by a method known per se, and the light rare earth element and heavy rare earth contained in the solution. Elements can be separated. At this time, since the solution rich in light rare earth elements contains more light rare earth elements than the object to be treated, the object to be treated itself is subjected to a solvent extraction method to separate the light rare earth elements and the heavy rare earth elements. Since the number of steps required for the extraction operation can be reduced as compared with the case where the extraction operation is performed, the amount of the extractant and the organic solvent used can be reduced and the size of the apparatus can be reduced. Further, even if the content ratio of the light rare earth element to the heavy rare earth element (content of the heavy rare earth element / content of the light rare earth element) contained in the object to be treated varies, for example, in the range of 0.05 to 0.50. Light rare earth element The content ratio of light rare earth element to heavy rare earth element (content of heavy rare earth element / content of light rare earth element) contained in the rich solution converges to the range of 0.02 to 0.10. This is a noteworthy point (however, it is 0.01 or more smaller than the content ratio of light rare earth elements and heavy rare earth elements (content of heavy rare earth elements / content of light rare earth elements) contained in the object to be treated). Therefore, if the content ratio of the contained light rare earth element to the heavy rare earth element (content of heavy rare earth element / content of light rare earth element) is, for example, a treatment target in the range of 0.05 to 0.50 (R-Fe). -The content ratio of the two in the B-based permanent magnet is within this range), and each time, it is included in the solution under the processing conditions that match the converged content ratio without having to analyze the object to be treated and obtain the content ratio of the two. Light rare earth elements and heavy rare earth elements can be separated. Further, the content ratio of the light rare earth element and the heavy rare earth element contained in the solution rich in the light rare earth element can be adjusted by changing the mixing amount of the organic acid with the inorganic acid, so that the treatment conditions for separating the two can be adjusted. There is a high degree of freedom when setting. The amount of light rare earth elements contained in the residue can be reduced by, for example, performing steps (2) to (6) on the heavy rare earth element-rich residue separated from the light rare earth element-rich solution. (The content ratio of heavy rare earth elements to light rare earth elements can be increased). In this case, the light rare earth element-rich solution separated from the heavy rare earth element-rich residue can be combined with the light rare earth element contained in the solution by subjecting it to a solvent extraction method by a method known per se as the rare earth element solution of the present invention. As described above, heavy rare earth elements can be separated.

以下、本発明を実施例によって詳細に説明するが、本発明は以下の記載に限定して解釈されるものではない。 Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not construed as being limited to the following description.

実施例１：モデル実験その１
６０℃に加熱した濃度が１．１ｍｏｌ／Ｌの塩酸５４００ｍＬ、１４５０ｍＬ、７５０ｍＬ、１００ｍＬに、それぞれ３４３ｇのＮｄ_２Ｏ_３試薬、９３ｇのＰｒ_６Ｏ_１１試薬、５３ｇのＤｙ_２Ｏ_３試薬、７ｇのＴｂ_４Ｏ_７試薬を添加して６時間撹拌することで、それぞれの希土類元素の塩酸溶液を調製した。調製したそれぞれの希土類元素の塩酸溶液を表１の割合で混合し、含まれる希土類元素の濃度が異なる３種類の塩酸溶液Ａ〜Ｃをそれぞれ３Ｌ調製した。 Example 1: Model experiment 1
_{343 g of Nd 2} O ₃ reagent, 93 g of Pr ₆ O ₁₁ reagent, 53 g of Dy ₂ O ₃ reagent, and 7 g of hydrochloric acid having a concentration of 1.1 mol / L heated to 60 ° C. in 5400 mL, 1450 mL, 750 mL, and 100 mL, respectively. A hydrochloric acid solution of each rare earth element was prepared by adding the Tb ₄ O _{7 reagent and stirring for 6 hours.} The prepared hydrochloric acid solutions of the rare earth elements were mixed at the ratios shown in Table 1, and 3 L of each of the three types of hydrochloric acid solutions A to C having different concentrations of the rare earth elements contained were prepared.

調製した３種類の塩酸溶液Ａ〜Ｃのそれぞれに、シュウ酸二水和物３９０ｇを加え、室温で２時間撹拌することで、水分を多量に含む白色粉末の沈殿物（軽希土類元素と重希土類元素のシュウ酸塩）を得た。得られた沈殿物を、アルミナるつぼに収容し、大気雰囲気で９００℃で２時間焼成することで、茶色の組成の異なる３種類の焼成物Ａ〜Ｃを得た。それぞれの焼成物の重量、ＳＥＭ・ＥＤＸ分析（使用装置：日立ハイテクノロジーズ社製のＳ８００、以下同じ）の結果、軽希土類元素（Ｎｄ，Ｐｒ）と重希土類元素（Ｄｙ，Ｔｂ）の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ）を表２に示す。なお、それぞれの焼成物は、軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物であることを、別途に行ったＸ線回析分析（使用装置：ブルカー・エイエックスエス社製のＤ８ＡＤＶＡＮＣＥ、以下同じ）において確認した。 390 g of oxalic acid dihydrate was added to each of the three prepared hydrochloric acid solutions A to C, and the mixture was stirred at room temperature for 2 hours to form a white powder precipitate containing a large amount of water (light rare earth element and heavy rare earth element). Elemental oxalate) was obtained. The obtained precipitate was placed in an alumina crucible and fired at 900 ° C. for 2 hours in an atmospheric atmosphere to obtain three types of fired products A to C having different brown compositions. As a result of the weight of each fired product and SEM / EDX analysis (device used: S800 manufactured by Hitachi High-Technologies Corporation, the same applies hereinafter), the content ratio of light rare earth elements (Nd, Pr) and heavy rare earth elements (Dy, Tb) ( W _HR / W _LR ) is shown in Table 2. It should be noted that each calcined product is a mixture of a composite oxide or an oxide of a light rare earth element and a heavy rare earth element, which was separately subjected to X-ray diffraction analysis (device used: manufactured by Bruker AXS Co., Ltd.). Confirmed in D8 ADVANCE, the same applies hereinafter).

濃度が１．１ｍｏｌ／Ｌの塩酸と、酢酸を用い、両者を各種の割合で混合し、表３に示す６種類の混合酸Ａ〜Ｆを調製した。 Hydrochloric acid having a concentration of 1.1 mol / L and acetic acid were used and both were mixed at various ratios to prepare 6 kinds of mixed acids A to F shown in Table 3.

焼成物Ｂを、６０℃に加熱した濃度が１．１ｍｏｌ／Ｌの塩酸と６種類の混合酸Ａ〜Ｆのそれぞれ１００ｍＬに、１８．９ｇ（塩酸と６種類の混合酸のそれぞれへの溶解上限量のほぼ３倍に相当）添加して２時間撹拌した後、残渣をろ過することで、酸溶液と残渣を分離した。得られた酸溶液にシュウ酸二水和物１３ｇを加えて室温で２時間撹拌することで白色の沈殿物を得、この沈殿物を大気雰囲気で９００℃で２時間焼成することで焼成物を得た。焼成物の重量とＳＥＭ・ＥＤＸ分析の結果から、焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：酸溶液に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べた。結果を図１に示す。図１から明らかなように、いずれの酸溶液に含まれる軽希土類元素と重希土類元素の含量比も、焼成物Ｂに含まれる軽希土類元素と重希土類元素の含量比（０．１３）よりも小さく、これらの酸溶液は軽希土類リッチな溶液（本発明の希土類元素溶液）であった。また、塩酸に対する酢酸の混合量を変えることで、酸溶液に含まれる軽希土類元素と重希土類元素の含量比を調整することができた（塩酸に対する酢酸の混合量を多くすると酸溶液に含まれる重希土類元素の量が多くなる）。一方、酸溶液から分離された残渣を大気雰囲気で９００℃で２時間焼成することで得られた焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：残渣に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べたところ、いずれの残渣に含まれる軽希土類元素と重希土類元素の含量比も、焼成物Ｂに含まれる軽希土類元素と重希土類元素の含量比よりも大きく、これらの残渣は重希土類リッチであった。 The calcined product B was heated to 60 ° C. in 100 mL each of hydrochloric acid having a concentration of 1.1 mol / L and 6 kinds of mixed acids A to F, and 18.9 g (dissolving in each of hydrochloric acid and 6 kinds of mixed acids). After adding (corresponding to about 3 times the limit amount) and stirring for 2 hours, the acid solution and the residue were separated by filtering the residue. 13 g of oxalic acid dihydrate was added to the obtained acid solution and stirred at room temperature for 2 hours to obtain a white precipitate, and this precipitate was calcined in an air atmosphere at 900 ° C. for 2 hours to obtain a calcined product. Obtained. Based on the weight of the fired product and the results of SEM / EDX analysis, the content ratio of light rare earth elements and heavy rare earth elements contained in the fired product ( _WHR / W _LR : content ratio of light rare earth elements and heavy rare earth elements contained in the acid solution) (Equivalent to) was investigated. The results are shown in FIG. As is clear from FIG. 1, the content ratio of the light rare earth element and the heavy rare earth element contained in any of the acid solutions is larger than the content ratio (0.13) of the light rare earth element and the heavy rare earth element contained in the calcined product B. Small, these acid solutions were light rare earth rich solutions (rare earth element solutions of the present invention). In addition, the content ratio of light rare earth elements and heavy rare earth elements contained in the acid solution could be adjusted by changing the mixing amount of acetic acid with hydrochloric acid (increasing the mixing amount of acetic acid with hydrochloric acid is contained in the acid solution). The amount of heavy rare earth elements increases). On the other hand, the content ratio of light rare earth elements and heavy rare earth elements contained in the calcined product obtained by calcining the residue separated from the acid solution at 900 ° C. for 2 hours in an air atmosphere ( _WHR / _WLR : contained in the residue). The content ratio of the light rare earth element to the heavy rare earth element) was examined, and the content ratio of the light rare earth element to the heavy rare earth element contained in any of the residues was also the content ratio of the light rare earth element and the heavy rare earth element contained in the fired product B. These residues were rich in heavy rare earths.

３種類の焼成物Ａ〜Ｃのそれぞれを、６０℃に加熱した混合酸Ｅ１００ｍＬに、溶解上限量の１．５倍、２．０倍、２．５倍、３．０倍、３．５倍に相当する量添加して２時間撹拌した後、残渣をろ過することで、酸溶液と残渣を分離した。得られた酸溶液にシュウ酸二水和物１３ｇを加えて室温で２時間撹拌することで白色の沈殿物を得、この沈殿物を大気雰囲気で９００℃で２時間焼成することで焼成物を得た。焼成物の重量とＳＥＭ・ＥＤＸ分析の結果から、焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：酸溶液に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べた。その結果、３種類の焼成物Ａ〜Ｃのそれぞれを混合酸Ｅに溶解上限量の２．０倍に相当する量添加した場合、焼成物Ａ由来の焼成物のＷ_ＨＲ／Ｗ_ＬＲは０．０９、焼成物Ｂ由来の焼成物のＷ_ＨＲ／Ｗ_ＬＲは０．０７、焼成物Ｃ由来の焼成物のＷ_ＨＲ／Ｗ_ＬＲは０．０５であり、３種類の焼成物Ａ〜Ｃの間でのＷ_ＨＲ／Ｗ_ＬＲのバラツキ幅０．１２が０．０４に収束した。この３種類の焼成物Ａ〜Ｃ由来の焼成物の間でのＷ_ＨＲ／Ｗ_ＬＲのバラツキ幅の収束は、３種類の焼成物Ａ〜Ｃのそれぞれを混合酸Ｅに溶解上限量の２．５倍、３．０倍、３．５倍に相当する量添加した場合にもほぼ維持されていた。また、３種類の焼成物Ａ〜Ｃのそれぞれを、混合酸Ｂ、混合酸Ｃ、混合酸Ｄ、混合酸Ｆのそれぞれに溶解上限量の２．０倍、２．５倍、３．０倍、３．５倍に相当する量添加した場合にも、３種類の焼成物Ａ〜Ｃ由来の焼成物の間でのＷ_ＨＲ／Ｗ_ＬＲのバラツキ幅の収束が認められた。 Each of the three types of fired products A to C was added to 100 mL of mixed acid E heated to 60 ° C. to 1.5 times, 2.0 times, 2.5 times, 3.0 times, and 3.5 times the upper limit of dissolution. After adding an amount corresponding to the above and stirring for 2 hours, the acid solution and the residue were separated by filtering the residue. 13 g of oxalic acid dihydrate was added to the obtained acid solution and stirred at room temperature for 2 hours to obtain a white precipitate, and this precipitate was calcined in an air atmosphere at 900 ° C. for 2 hours to obtain a calcined product. Obtained. Based on the weight of the fired product and the results of SEM / EDX analysis, the content ratio of light rare earth elements and heavy rare earth elements contained in the fired product ( _WHR / W _LR : content ratio of light rare earth elements and heavy rare earth elements contained in the acid solution) (Equivalent to) was investigated. As a result, when each of the three types of fired products A to C was added to the mixed acid E in an amount corresponding to 2.0 times the upper limit of dissolution, the _WHR / W _LR of the fired product derived from the fired product A was 0. 09, _{_W} HR _/ _W _LR of the burned material B from the calcined product 0.07, _{_W} HR _/ _W _LR of the burned material C from the calcined product was 0.05, while three of the burned material A~C The variation width of 0.12 for W _HR / W _LR in 1) converged to 0.04. _{Convergence of the variation width of WHR} / W _LR among the fired products derived from the three types of fired products A to C is such that each of the three types of fired products A to C is dissolved in the mixed acid E as the upper limit amount of 2. It was almost maintained even when the amounts corresponding to 5 times, 3.0 times, and 3.5 times were added. Further, each of the three types of fired products A to C was dissolved in the mixed acid B, the mixed acid C, the mixed acid D, and the mixed acid F at 2.0 times, 2.5 times, and 3.0 times the upper limit of dissolution, respectively. Even when an amount corresponding to 3.5 times was added, convergence of the variation width of _WHR / _WLR among the fired products derived from the three types of fired products A to C was observed.

なお、塩酸と酢酸の混合酸を用いて得た軽希土類元素と重希土類元素を含む酸溶液を水相として溶媒抽出法に付しても、塩酸に酢酸を混合したことが、軽希土類元素と重希土類元素の分離に対して悪影響を与えることはなかった（塩酸を用いて得た軽希土類元素と重希土類元素を含む酸溶液を水相として溶媒抽出法に付した場合の抽出挙動と差異がない）。 Even if an acid solution containing a light rare earth element and a heavy rare earth element obtained by using a mixed acid of hydrochloric acid and acetic acid is subjected to a solvent extraction method as an aqueous phase, the mixing of hydrochloric acid with acetic acid is a result of the light rare earth element. It did not adversely affect the separation of heavy rare earth elements (differences from the extraction behavior when an acid solution containing light rare earth elements and heavy rare earth elements obtained using hydrochloric acid was subjected to a solvent extraction method as an aqueous phase. Absent).

実施例２：モデル実験その２
濃度が１．１ｍｏｌ／Ｌの塩酸と、クエン酸を用い、両者を各種の割合で混合し、表４に示す５種類の混合酸Ｇ〜Ｋを調製した。 Example 2: Model experiment 2
Hydrochloric acid having a concentration of 1.1 mol / L and citric acid were used and both were mixed at various ratios to prepare five kinds of mixed acids G to K shown in Table 4.

実施例１における焼成物Ｂを、６０℃に加熱した濃度が１．１ｍｏｌ／Ｌの塩酸と５種類の混合酸Ｇ〜Ｋのそれぞれ１００ｍＬに、１８．９ｇ（塩酸と５種類の混合酸のそれぞれへの溶解上限量のほぼ３倍に相当）添加して２時間撹拌した後、残渣をろ過することで、酸溶液と残渣を分離した。得られた酸溶液にシュウ酸二水和物１３ｇを加えて室温で２時間撹拌することで白色の沈殿物を得、この沈殿物を大気雰囲気で９００℃で２時間焼成することで焼成物を得た。焼成物の重量とＳＥＭ・ＥＤＸ分析の結果から、焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：酸溶液に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べた。結果を図２に示す。図２から明らかなように、いずれの酸溶液に含まれる軽希土類元素と重希土類元素の含量比も、焼成物Ｂに含まれる軽希土類元素と重希土類元素の含量比（０．１３）よりも小さく、これらの酸溶液は軽希土類リッチな溶液（本発明の希土類元素溶液）であった。また、塩酸に対するクエン酸の混合量を変えることで、酸溶液に含まれる軽希土類元素と重希土類元素の含量比を調整することができた（塩酸に対するクエン酸の混合量が多くなると酸溶液に含まれる重希土類元素の量が多くなる）。一方、酸溶液から分離された残渣を大気雰囲気で９００℃で２時間焼成することで得られた焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：残渣に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べたところ、いずれの残渣に含まれる軽希土類元素と重希土類元素の含量比も、焼成物Ｂに含まれる軽希土類元素と重希土類元素の含量比よりも大きく、これらの残渣は重希土類リッチであった。 The calcined product B in Example 1 was heated to 60 ° C. in 100 mL each of hydrochloric acid having a concentration of 1.1 mol / L and five kinds of mixed acids G to K, and 18.9 g (each of hydrochloric acid and five kinds of mixed acids). The acid solution and the residue were separated by filtering the residue after adding the mixture (corresponding to about 3 times the upper limit of dissolution in) and stirring for 2 hours. 13 g of oxalic acid dihydrate was added to the obtained acid solution and stirred at room temperature for 2 hours to obtain a white precipitate, and this precipitate was calcined in an air atmosphere at 900 ° C. for 2 hours to obtain a calcined product. Obtained. Based on the weight of the fired product and the results of SEM / EDX analysis, the content ratio of light rare earth elements and heavy rare earth elements contained in the fired product ( _WHR / W _LR : content ratio of light rare earth elements and heavy rare earth elements contained in the acid solution) (Equivalent to) was investigated. The results are shown in FIG. As is clear from FIG. 2, the content ratio of the light rare earth element and the heavy rare earth element contained in any of the acid solutions is also higher than the content ratio of the light rare earth element and the heavy rare earth element (0.13) contained in the calcined product B. Small, these acid solutions were light rare earth rich solutions (rare earth element solutions of the present invention). In addition, by changing the mixing amount of citric acid with hydrochloric acid, the content ratio of light rare earth elements and heavy rare earth elements contained in the acid solution could be adjusted (when the mixing amount of citric acid with hydrochloric acid increases, the acid solution becomes an acid solution. The amount of heavy rare earth elements contained will increase). On the other hand, the content ratio of light rare earth elements and heavy rare earth elements contained in the calcined product obtained by calcining the residue separated from the acid solution at 900 ° C. for 2 hours in an air atmosphere ( _WHR / _WLR : contained in the residue). The content ratio of the light rare earth element to the heavy rare earth element) was examined, and the content ratio of the light rare earth element to the heavy rare earth element contained in any of the residues was also the content ratio of the light rare earth element and the heavy rare earth element contained in the fired product B. These residues were rich in heavy rare earths.

実施例１における３種類の焼成物Ａ〜Ｃのそれぞれを、６０℃に加熱した混合酸Ｊ１００ｍＬに、溶解上限量の１．５倍、２．０倍、２．５倍、３．０倍、３．５倍に相当する量添加して２時間撹拌した後、残渣をろ過することで、酸溶液と残渣を分離した。得られた酸溶液にシュウ酸二水和物１３ｇを加えて室温で２時間撹拌することで白色の沈殿物を得、この沈殿物を大気雰囲気で９００℃で２時間焼成することで焼成物を得た。焼成物の重量とＳＥＭ・ＥＤＸ分析の結果から、焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：酸溶液に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べた。その結果、３種類の焼成物Ａ〜Ｃのそれぞれを混合酸Ｊに溶解上限量の３．０倍に相当する量添加した場合、焼成物Ａ由来の焼成物のＷ_ＨＲ／Ｗ_ＬＲは０．０７、焼成物Ｂ由来の焼成物のＷ_ＨＲ／Ｗ_ＬＲは０．０６、焼成物Ｃ由来の焼成物のＷ_ＨＲ／Ｗ_ＬＲは０．０３であり、３種類の焼成物Ａ〜Ｃの間でのＷ_ＨＲ／Ｗ_ＬＲのバラツキ幅０．１２が０．０４に収束した。この３種類の焼成物Ａ〜Ｃ由来の焼成物の間でのＷ_ＨＲ／Ｗ_ＬＲのバラツキ幅の収束は、３種類の焼成物Ａ〜Ｃのそれぞれを混合酸Ｊに溶解上限量の３．５倍に相当する量添加した場合にもほぼ維持されていた。また、３種類の焼成物Ａ〜Ｃのそれぞれを、その他の混合酸に溶解上限量の３．０倍、３．５倍に相当する量添加した場合にも、３種類の焼成物Ａ〜Ｃ由来の焼成物の間でのＷ_ＨＲ／Ｗ_ＬＲのバラツキ幅の収束が認められた。 Each of the three types of fired products A to C in Example 1 was added to 100 mL of the mixed acid J heated to 60 ° C. to 1.5 times, 2.0 times, 2.5 times, and 3.0 times the upper limit of dissolution. The acid solution and the residue were separated by filtering the residue after adding an amount corresponding to 3.5 times and stirring for 2 hours. 13 g of oxalic acid dihydrate was added to the obtained acid solution and stirred at room temperature for 2 hours to obtain a white precipitate, and this precipitate was calcined in an air atmosphere at 900 ° C. for 2 hours to obtain a calcined product. Obtained. Based on the weight of the fired product and the results of SEM / EDX analysis, the content ratio of light rare earth elements and heavy rare earth elements contained in the fired product ( _WHR / W _LR : content ratio of light rare earth elements and heavy rare earth elements contained in the acid solution) (Equivalent to) was investigated. As a result, when each of the three types of fired products A to C was added to the mixed acid J in an amount corresponding to 3.0 times the upper limit of dissolution, the _WHR / W _LR of the fired product derived from the fired product A was 0. 07, _{_W} HR _/ _W _LR of the burned material B from the calcined product 0.06, _{_W} HR _/ _W _LR of the burned material C from the calcined product was 0.03, while three of the burned material A~C The variation width of 0.12 for W _HR / W _LR in 1) converged to 0.04. _{Convergence of the variation width of WHR} / W _LR among the fired products derived from the three types of fired products A to C is the upper limit of the amount of dissolution of each of the three types of fired products A to C in the mixed acid J. It was almost maintained even when the amount corresponding to 5 times was added. Further, when each of the three types of fired products A to C is added to other mixed acids in an amount corresponding to 3.0 times or 3.5 times the upper limit of dissolution, the three types of fired products A to C are also added. Convergence of the variation width of _WHR / _WLR between the derived calcined products was observed.

なお、塩酸とクエン酸の混合酸を用いて得た軽希土類元素と重希土類元素を含む酸溶液を水相として溶媒抽出法に付しても、塩酸にクエン酸を混合したことが、軽希土類元素と重希土類元素の分離に対して悪影響を与えることはなかった（塩酸を用いて得た軽希土類元素と重希土類元素を含む酸溶液を水相として溶媒抽出法に付した場合の抽出挙動と差異がない）。 Even if an acid solution containing a light rare earth element and a heavy rare earth element obtained by using a mixed acid of hydrochloric acid and citric acid was subjected to a solvent extraction method as an aqueous phase, the mixture of hydrochloric acid and citric acid was found in light rare earths. It did not adversely affect the separation of elements and heavy rare earth elements (extraction behavior when an acid solution containing light rare earth elements and heavy rare earth elements obtained using hydrochloric acid was subjected to a solvent extraction method as an aqueous phase. There is no difference).

実施例３：軽希土類元素（Ｎｄ，Ｐｒ）と重希土類元素（Ｄｙ）の分離
（工程１）
Ｒ−Ｆｅ−Ｂ系永久磁石の製造工程中に発生した約１０μｍの粒径を有する磁石加工屑（自然発火防止のため水中で７日間保管したもの）に対し、吸引ろ過することで脱水してからロータリーキルンを用いて燃焼処理することで酸化処理を行った。こうして酸化処理を行った磁石加工屑のＩＣＰ分析（使用装置：島津製作所社製のＩＣＰＶ−１０１７）の結果を表５に示す。 Example 3: Separation of light rare earth elements (Nd, Pr) and heavy rare earth elements (Dy) (step 1)
Magnet processing scraps with a particle size of about 10 μm (stored in water for 7 days to prevent spontaneous combustion) generated during the manufacturing process of R-Fe-B permanent magnets are dehydrated by suction filtration. Oxidation treatment was performed by combustion treatment using a rotary kiln. Table 5 shows the results of ICP analysis (equipment used: ICPV-1017 manufactured by Shimadzu Corporation) of the magnet processing waste subjected to the oxidation treatment in this way.

次に、酸化処理を行った磁石加工屑５０ｇとカーボンブラック（東海カーボン社製のファーネスブラック、以下同じ）１０ｇを混合し、カーボンブラック１０ｇを予め底面に敷き詰めた寸法が内径５０ｍｍ×深さ５０ｍｍ×肉厚１０ｍｍの炭素るつぼ（黒鉛製）に収容した後、電気炉を用い、工業用アルゴンガス雰囲気（酸素含有濃度：０．２ｐｐｍ、流量：１０Ｌ／分。以下同じ）中で１４５０℃まで１０℃／分で昇温してから１時間熱処理した。その後、炉内の加熱を停止し、炉内の工業用アルゴンガス雰囲気を維持したまま、炭素るつぼを室温まで炉冷した。炉冷を終了した後、炭素るつぼ内には、互いに独立かつ密接して存在する２種類の塊状物（塊状物Ａと塊状物Ｂ）が存在した。塊状物Ａと塊状物ＢのそれぞれのＳＥＭ・ＥＤＸ分析を行ったところ、塊状物Ａの主成分は鉄である一方、塊状物Ｂの主成分は希土類元素の酸化物であった。塊状物ＢのＳＥＭ・ＥＤＸ分析の結果（Ｎｄ，Ｐｒ，Ｄｙのみ）を表６に示す（鉄は検出限界以下）。なお、塊状物Ｂの主成分である希土類元素の酸化物は、軽希土類元素（Ｎｄ，Ｐｒ）と重希土類元素（Ｄｙ）の複合酸化物ないし酸化物の混合物であることを、別途に行ったＸ線回析分析において確認した。 Next, 50 g of oxidized graphite scraps and 10 g of carbon black (Furness black manufactured by Tokai Carbon Co., Ltd., the same applies hereinafter) are mixed, and 10 g of carbon black is spread on the bottom surface in advance. After being housed in a carbon crucible (made of graphite) with a wall thickness of 10 mm, it is stored at 10 ° C. up to 1450 ° C. in an industrial argon gas atmosphere (oxygen content concentration: 0.2 ppm, flow rate: 10 L / min, the same applies hereinafter) using an electric furnace. The temperature was raised at / min and then heat-treated for 1 hour. After that, the heating in the furnace was stopped, and the carbon crucible was cooled to room temperature while maintaining the industrial argon gas atmosphere in the furnace. After the furnace cooling was completed, there were two types of lumps (lump A and lump B) that existed independently and in close contact with each other in the carbon crucible. SEM / EDX analysis of each of the lump A and the lump B revealed that the main component of the lump A was iron, while the main component of the lump B was an oxide of a rare earth element. The results of SEM / EDX analysis of the mass B (Nd, Pr, Dy only) are shown in Table 6 (iron is below the detection limit). The oxide of the rare earth element, which is the main component of the lump B, is separately a mixture of a composite oxide or an oxide of a light rare earth element (Nd, Pr) and a heavy rare earth element (Dy). It was confirmed by X-ray diffraction analysis.

（工程２）
工程１で得た希土類元素の酸化物を主成分とする塊状物Ｂを、瑪瑙製の乳鉢と乳棒で粉砕し、ステンレス製の篩を用いて粒径が１２５μｍ未満の粉末を得る操作を複数回行うことで、約１ｋｇの塊状物Ｂの粉末を調製した。こうして調製した塊状物Ｂの粉末７５ｇを、濃度が１．０ｍｏｌ／Ｌの塩酸１Ｌに加え、８０℃で６時間撹拌した後、残渣をろ過することで、塊状物Ｂの塩酸溶液を得た。 (Step 2)
The mass B mainly composed of the rare earth element oxide obtained in step 1 is crushed with an agate mortar and pestle, and a stainless steel sieve is used to obtain a powder having a particle size of less than 125 μm multiple times. By doing so, about 1 kg of a mass B powder was prepared. 75 g of the lump B powder thus prepared was added to 1 L of hydrochloric acid having a concentration of 1.0 mol / L, stirred at 80 ° C. for 6 hours, and then the residue was filtered to obtain a hydrochloric acid solution of the lump B.

（工程３）
工程２で得た塊状物Ｂの塩酸溶液１Ｌに、シュウ酸二水和物１３０ｇを加え、室温で２時間撹拌することで、水分を多量に含む白色粉末の沈殿物（軽希土類元素と重希土類元素のシュウ酸塩）を約１００ｇ得た。 (Step 3)
130 g of oxalic acid dihydrate was added to 1 L of the hydrochloric acid solution of the mass B obtained in step 2, and the mixture was stirred at room temperature for 2 hours to form a white powder precipitate containing a large amount of water (light rare earth elements and heavy rare earths). Elemental oxalate) was obtained in an amount of about 100 g.

（工程４）
工程３で得た沈殿物を、アルミナるつぼに収容し、大気雰囲気で９００℃で２時間焼成することで、茶色の焼成物を６５．５ｇ得た。この焼成物のＳＥＭ・ＥＤＸ分析の結果（Ｎｄ，Ｐｒ，Ｄｙのみ）を表７に示す。なお、この焼成物は、軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物であることを、別途に行ったＸ線回析分析において確認した。 (Step 4)
The precipitate obtained in step 3 was placed in an alumina crucible and calcined at 900 ° C. for 2 hours in an atmospheric atmosphere to obtain 65.5 g of a brown calcined product. Table 7 shows the results of SEM / EDX analysis of this fired product (Nd, Pr, Dy only). It was confirmed by a separate X-ray diffraction analysis that this calcined product was a composite oxide or a mixture of a light rare earth element and a heavy rare earth element.

（工程５）
６０℃に加熱した実施例１における混合酸Ｅ１００ｍＬに、溶解上限量の２．０倍に相当する量の工程４で得た焼成物を添加して撹拌した。なお、用いる混合酸Ｅに対する工程４で得た焼成物の溶解上限量（６．５５ｇ）は、混合酸Ｅに焼成物を少量ずつ溶解することで実験的に求めた。 (Step 5)
To 100 mL of the mixed acid E in Example 1 heated to 60 ° C., an amount of the calcined product obtained in Step 4 corresponding to 2.0 times the upper limit of dissolution was added and stirred. The upper limit of dissolution (6.55 g) of the fired product obtained in step 4 with respect to the mixed acid E to be used was experimentally determined by dissolving the fired product in the mixed acid E little by little.

（工程６）
工程５における撹拌を開始してから２時間後、残渣をろ過することで、酸溶液と残渣を分離した。得られた酸溶液にシュウ酸二水和物１３ｇを加えて室温で２時間撹拌することで白色の沈殿物を得、この沈殿物を大気雰囲気で９００℃で２時間焼成することで焼成物を得た。焼成物の重量とＳＥＭ・ＥＤＸ分析の結果から、焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：酸溶液に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べたところ０．０９であり、酸溶液に含まれる軽希土類元素と重希土類元素の含量比は、工程４で得た焼成物に含まれる軽希土類元素と重希土類元素の含量比（０．２１）よりも小さく、この酸溶液は軽希土類リッチな溶液（本発明の希土類元素溶液）であった。一方、酸溶液から分離された残渣を大気雰囲気で９００℃で２時間焼成することで得られた焼成物に含まれる軽希土類元素と重希土類元素の含量比（Ｗ_ＨＲ／Ｗ_ＬＲ：残渣に含まれる軽希土類元素と重希土類元素の含量比に相当）を調べたところ、残渣に含まれる軽希土類元素と重希土類元素の含量比は、工程４で得た焼成物に含まれる軽希土類元素と重希土類元素の含量比よりも大きく、この残渣は重希土類リッチであった。 (Step 6)
Two hours after the start of stirring in step 5, the acid solution and the residue were separated by filtering the residue. 13 g of oxalic acid dihydrate was added to the obtained acid solution and stirred at room temperature for 2 hours to obtain a white precipitate, and this precipitate was calcined in an air atmosphere at 900 ° C. for 2 hours to obtain a calcined product. Obtained. Based on the weight of the fired product and the results of SEM / EDX analysis, the content ratio of light rare earth elements and heavy rare earth elements contained in the fired product ( _WHR / W _LR : content ratio of light rare earth elements and heavy rare earth elements contained in the acid solution) The content ratio of the light rare earth element and the heavy rare earth element contained in the acid solution is 0.09, and the content ratio of the light rare earth element and the heavy rare earth element contained in the fired product obtained in step 4 is 0.09. Smaller than (0.21), this acid solution was a light rare earth rich solution (rare earth element solution of the present invention). On the other hand, the content ratio of light rare earth elements and heavy rare earth elements contained in the calcined product obtained by calcining the residue separated from the acid solution at 900 ° C. for 2 hours in an air atmosphere ( _WHR / _WLR : contained in the residue). The content ratio of the light rare earth element to the heavy rare earth element) was examined, and the content ratio of the light rare earth element to the heavy rare earth element contained in the residue was the same as that of the light rare earth element contained in the fired product obtained in step 4. Larger than the rare earth element content ratio, this residue was heavy rare earth rich.

実施例４：
実施例１における混合酸Ｅのかわりに、濃度が１．３ｍｏｌ／Ｌの硝酸と酢酸からなる混合酸（硝酸濃度：１．１ｍｏｌ／Ｌ＋酢酸濃度：０．２ｍｏｌ／Ｌ）を用いること以外は、実施例３と同様にして、軽希土類元素と重希土類元素の含量比が、実施例３で得た本発明の希土類元素溶液とほぼ同じの、軽希土類リッチな溶液である本発明の希土類元素溶液を得た。 Example 4:
Except for using a mixed acid (nitric acid concentration: 1.1 mol / L + acetic acid concentration: 0.2 mol / L) composed of nitric acid and acetic acid having a concentration of 1.3 mol / L instead of the mixed acid E in Example 1. Similar to Example 3, the rare earth element solution of the present invention is a light rare earth-rich solution in which the content ratio of the light rare earth element to the heavy rare earth element is almost the same as the rare earth element solution of the present invention obtained in Example 3. Got

実施例５：
実施例１における混合酸Ｅのかわりに、濃度が１．１ｍｏｌ／Ｌの塩酸と乳酸からなる混合酸（塩酸濃度：１．０ｍｏｌ／Ｌ＋乳酸濃度：０．１ｍｏｌ／Ｌ）を用いること以外は、実施例３と同様にして、軽希土類元素と重希土類元素の含量比が、実施例３で得た本発明の希土類元素溶液とほぼ同じの、軽希土類リッチな溶液である本発明の希土類元素溶液を得た。 Example 5:
Except for using a mixed acid consisting of hydrochloric acid and lactic acid having a concentration of 1.1 mol / L (hydrochloric acid concentration: 1.0 mol / L + lactic acid concentration: 0.1 mol / L) instead of the mixed acid E in Example 1. Similar to Example 3, the rare earth element solution of the present invention is a light rare earth-rich solution in which the content ratio of the light rare earth element to the heavy rare earth element is almost the same as the rare earth element solution of the present invention obtained in Example 3. Got

実施例６：
実施例１における混合酸Ｅのかわりに、濃度が１．１ｍｏｌ／Ｌの塩酸とアセチルアセトン酸からなる混合酸（塩酸濃度：０．８ｍｏｌ／Ｌ＋アセチルアセトン酸濃度：０．３ｍｏｌ／Ｌ）を用いること以外は、実施例３と同様にして、軽希土類元素と重希土類元素の含量比が、実施例３で得た本発明の希土類元素溶液とほぼ同じの、軽希土類リッチな溶液である本発明の希土類元素溶液を得た。 Example 6:
Except for using a mixed acid composed of hydrochloric acid having a concentration of 1.1 mol / L and acetylacetoneic acid (hydrochloric acid concentration: 0.8 mol / L + acetylacetate acid concentration: 0.3 mol / L) instead of the mixed acid E in Example 1. Is a light rare earth-rich solution of the present invention in which the content ratio of the light rare earth element to the heavy rare earth element is almost the same as that of the rare earth element solution of the present invention obtained in Example 3 in the same manner as in Example 3. An elemental solution was obtained.

実施例７：
実施例１における混合酸Ｅのかわりに、濃度が１．１ｍｏｌ／Ｌの塩酸とα−ヒドロキシイソ酪酸からなる混合酸（塩酸濃度：０．８ｍｏｌ／Ｌ＋α−ヒドロキシイソ酪酸濃度：０．３ｍｏｌ／Ｌ）を用いること以外は、実施例３と同様にして、軽希土類元素と重希土類元素の含量比が、実施例３で得た本発明の希土類元素溶液とほぼ同じの、軽希土類リッチな溶液である本発明の希土類元素溶液を得た。 Example 7:
Instead of the mixed acid E in Example 1, a mixed acid composed of hydrochloric acid having a concentration of 1.1 mol / L and α-hydroxyisobutyric acid (hydrochloric acid concentration: 0.8 mol / L + α-hydroxyisobutyric acid concentration: 0.3 mol / L) ), In the same manner as in Example 3, the content ratio of the light rare earth element to the heavy rare earth element is almost the same as the rare earth element solution of the present invention obtained in Example 3, and the solution is rich in light rare earth. A rare earth element solution of the present invention was obtained.

実施例８：
実施例１における混合酸Ｅのかわりに、濃度が２．０ｍｏｌ／Ｌの塩酸と酢酸からなる混合酸（塩酸濃度：１．５ｍｏｌ／Ｌ＋酢酸濃度：０．５ｍｏｌ／Ｌ）を用いること以外は、実施例３と同様にして、軽希土類元素と重希土類元素の含量比が、実施例３で得た本発明の希土類元素溶液とほぼ同じの、軽希土類リッチな溶液である本発明の希土類元素溶液を得た。 Example 8:
Except for using a mixed acid consisting of hydrochloric acid and acetic acid having a concentration of 2.0 mol / L (hydrochloric acid concentration: 1.5 mol / L + acetic acid concentration: 0.5 mol / L) instead of the mixed acid E in Example 1. Similar to Example 3, the rare earth element solution of the present invention is a light rare earth-rich solution in which the content ratio of the light rare earth element to the heavy rare earth element is almost the same as the rare earth element solution of the present invention obtained in Example 3. Got

実施例９：
実施例１における混合酸Ｅのかわりに、濃度が３．０ｍｏｌ／Ｌの塩酸と酢酸からなる混合酸（塩酸濃度：２．５ｍｏｌ／Ｌ＋酢酸濃度：０．５ｍｏｌ／Ｌ）を用いること以外は、実施例３と同様にして、軽希土類元素と重希土類元素の含量比が、実施例３で得た本発明の希土類元素溶液とほぼ同じの、軽希土類リッチな溶液である本発明の希土類元素溶液を得た。 Example 9:
Except for using a mixed acid consisting of hydrochloric acid and acetic acid having a concentration of 3.0 mol / L (hydrochloric acid concentration: 2.5 mol / L + acetic acid concentration: 0.5 mol / L) instead of the mixed acid E in Example 1. Similar to Example 3, the rare earth element solution of the present invention is a light rare earth-rich solution in which the content ratio of the light rare earth element to the heavy rare earth element is almost the same as the rare earth element solution of the present invention obtained in Example 3. Got

実施例１０：
実施例１における混合酸Ｅのかわりに、濃度が３．０ｍｏｌ／Ｌの硝酸とクエン酸からなる混合酸（硝酸濃度：２．０ｍｏｌ／Ｌ＋クエン酸濃度：１．０ｍｏｌ／Ｌ）を用いること以外は、実施例３と同様にして、軽希土類元素と重希土類元素の含量比が、実施例３で得た本発明の希土類元素溶液とほぼ同じの、軽希土類リッチな溶液である本発明の希土類元素溶液を得た。 Example 10:
Except for using a mixed acid (nitric acid concentration: 2.0 mol / L + citric acid concentration: 1.0 mol / L) composed of nitric acid and citric acid having a concentration of 3.0 mol / L instead of the mixed acid E in Example 1. Is a light rare earth-rich solution of the present invention in which the content ratio of the light rare earth element to the heavy rare earth element is almost the same as that of the rare earth element solution of the present invention obtained in Example 3 in the same manner as in Example 3. An elemental solution was obtained.

本発明は、例えば溶媒抽出法によって軽希土類元素と重希土類元素を含む処理対象物から両者を分離するに際し、抽出剤や有機溶媒の使用量の低減化や装置の小型化を可能にしたり、処理対象物に含まれる軽希土類元素と重希土類元素の含量比の分析などの工程上の作業負担の軽減化を可能にしたりする、希土類元素溶液を調製する方法を提供することができる点において産業上の利用可能性を有する。 The present invention enables reduction of the amount of extractant and organic solvent used, miniaturization of an apparatus, and treatment when separating both from a treatment target containing a light rare earth element and a heavy rare earth element by, for example, a solvent extraction method. Industrially, it is possible to provide a method for preparing a rare earth element solution, which makes it possible to reduce the work load in the process such as analysis of the content ratio of the light rare earth element and the heavy rare earth element contained in the object. Has the availability of.

Claims

（１）軽希土類元素と重希土類元素を含む処理対象物から両者の複合酸化物ないし酸化物の混合物を得る工程
（２）得られた軽希土類元素と重希土類元素の複合酸化物ないし酸化物の混合物を、塩酸および／または硝酸に溶解する工程
（３）得られた溶液に沈殿剤を加えて沈殿物を得る工程
（４）得られた沈殿物を焼成する工程
（５）得られた焼成物を、濃度が０．７ｍｏｌ／Ｌ以上の、塩酸および硝酸から選ばれる少なくとも１つの無機酸と、酢酸、クエン酸、乳酸、アセチルアセトン酸、α−ヒドロキシイソ酪酸から選ばれる少なくとも１つの有機酸からなる混合酸に、溶解上限量の１．５倍以上添加して、軽希土類元素リッチな溶液と重希土類元素リッチな残渣を得る工程（混合酸の濃度は無機酸の濃度と有機酸の濃度の合計濃度）
（６）得られた溶液を残渣から分離する工程を少なくとも含んでなることを特徴とする希土類元素溶液を調製する方法（ここで「リッチ」なる用語は該当する希土類元素の他方の希土類元素に対する質量比が処理対象物における質量比よりも大きいことを意味する）。 (1) Step of obtaining a composite oxide or a mixture of oxides of both from a treatment target containing a light rare earth element and a heavy rare earth element (2) A composite oxide or oxide of the obtained light rare earth element and a heavy rare earth element Step of dissolving the mixture in hydrochloric acid and / or nitric acid (3) Step of adding a precipitant to the obtained solution to obtain a precipitate (4) Step of firing the obtained precipitate (5) Step of calcining the obtained precipitate Consists of at least one inorganic acid selected from hydrochloric acid and nitric acid having a concentration of 0.7 mol / L or more, and at least one organic acid selected from acetic acid, citric acid, lactic acid, acetylacetate acid, and α-hydroxyisobutyric acid. A step of adding 1.5 times or more of the upper limit of dissolution to a mixed acid to obtain a solution rich in light rare earth elements and a residue rich in heavy rare earth elements (the concentration of mixed acid is the sum of the concentration of inorganic acid and the concentration of organic acid). concentration)
(6) A method for preparing a rare earth element solution, which comprises at least a step of separating the obtained solution from the residue (here, the term “rich” refers to the quality of the relevant rare earth element with respect to the other rare earth element. means that the ratio is greater than the mass ratio in the processing object).

沈殿剤としてシュウ酸、酢酸、炭酸の金属塩から選ばれる少なくとも１つを用いることを特徴とする請求項１記載の方法。 The method according to claim 1, wherein at least one selected from a metal salt of oxalic acid, acetic acid, and carbonic acid is used as the precipitant.

処理対象物がＲ−Ｆｅ−Ｂ系永久磁石であることを特徴とする請求項１記載の方法。 The method according to claim 1, wherein the object to be processed is an R-Fe-B-based permanent magnet.

処理対象物に含まれる軽希土類元素と重希土類元素の質量比（重希土類元素の含量（ｍａｓｓ％）／軽希土類元素の含量（ｍａｓｓ％））が０．０５〜０．５０であることを特徴とする請求項１記載の方法。 The mass ratio of the light rare earth element and a heavy rare-earth element contained in the processing object (the content of the heavy content of rare earth elements (mass%) / light rare earth elements (mass%)) is 0.05 to 0.50 The method according to claim 1, which is characterized.

軽希土類元素リッチな溶液に含まれる軽希土類元素と重希土類元素の質量比（重希土類元素の含量（ｍａｓｓ％）／軽希土類元素の含量（ｍａｓｓ％））が０．０２〜０．１０であり、かつ、処理対象物に含まれる軽希土類元素と重希土類元素の質量比（重希土類元素の含量（ｍａｓｓ％）／軽希土類元素の含量（ｍａｓｓ％））よりも０．０１以上小さいことを特徴とする請求項１記載の方法。
In mass ratio of the light rare earth element and a heavy rare-earth element contained in the light rare earth element-rich solution (content of the heavy content of rare earth elements (mass%) / light rare earth elements (mass%)) is 0.02 to 0.10 There, and mass ratio of the light rare earth element and a heavy rare-earth element contained in the processing object 0.01 small that more than (the heavy rare earth element content (mass%) / content of the light rare earth elements (mass%)) The method according to claim 1, wherein the method is characterized by.