JP5392828B2 - Extraction and separation method of rare earth elements - Google Patents
Extraction and separation method of rare earth elements Download PDFInfo
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims description 148
- 238000000605 extraction Methods 0.000 title claims description 69
- 238000000926 separation method Methods 0.000 title claims description 60
- 239000012074 organic phase Substances 0.000 claims description 106
- 239000008346 aqueous phase Substances 0.000 claims description 49
- 239000002253 acid Substances 0.000 claims description 43
- 238000000034 method Methods 0.000 claims description 34
- 239000007864 aqueous solution Substances 0.000 claims description 32
- 229910052779 Neodymium Inorganic materials 0.000 claims description 25
- 239000000243 solution Substances 0.000 claims description 25
- 229910052777 Praseodymium Inorganic materials 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- CNDWHJQEGZZDTQ-UHFFFAOYSA-N 2-(2-amino-2-oxoethoxy)acetamide Chemical compound NC(=O)COCC(N)=O CNDWHJQEGZZDTQ-UHFFFAOYSA-N 0.000 claims description 13
- 238000005406 washing Methods 0.000 claims description 13
- 229910052684 Cerium Inorganic materials 0.000 claims description 7
- 229910052772 Samarium Inorganic materials 0.000 claims description 7
- 125000000217 alkyl group Chemical group 0.000 claims description 6
- 125000004432 carbon atom Chemical group C* 0.000 claims description 6
- 229910052746 lanthanum Inorganic materials 0.000 claims description 6
- 239000002904 solvent Substances 0.000 claims description 6
- 229910052693 Europium Inorganic materials 0.000 claims description 5
- 239000011260 aqueous acid Substances 0.000 claims description 4
- 239000012071 phase Substances 0.000 claims description 3
- 230000002378 acidificating effect Effects 0.000 claims description 2
- 150000002910 rare earth metals Chemical class 0.000 description 22
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 18
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- 238000004140 cleaning Methods 0.000 description 13
- KOHUSHSNNOEPFN-UHFFFAOYSA-N 2-[2-(dioctylamino)-2-oxoethoxy]acetic acid Chemical compound CCCCCCCCN(C(=O)COCC(O)=O)CCCCCCCC KOHUSHSNNOEPFN-UHFFFAOYSA-N 0.000 description 12
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 12
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 12
- 238000000638 solvent extraction Methods 0.000 description 12
- 230000000052 comparative effect Effects 0.000 description 11
- ZDFBXXSHBTVQMB-UHFFFAOYSA-N 2-ethylhexoxy(2-ethylhexyl)phosphinic acid Chemical compound CCCCC(CC)COP(O)(=O)CC(CC)CCCC ZDFBXXSHBTVQMB-UHFFFAOYSA-N 0.000 description 10
- 238000005191 phase separation Methods 0.000 description 7
- 229910052692 Dysprosium Inorganic materials 0.000 description 5
- 229910052771 Terbium Inorganic materials 0.000 description 5
- 239000000284 extract Substances 0.000 description 5
- 239000011259 mixed solution Substances 0.000 description 5
- ATINCSYRHURBSP-UHFFFAOYSA-K neodymium(iii) chloride Chemical compound Cl[Nd](Cl)Cl ATINCSYRHURBSP-UHFFFAOYSA-K 0.000 description 5
- -1 phosphonic acid compound Chemical class 0.000 description 5
- LHBNLZDGIPPZLL-UHFFFAOYSA-K praseodymium(iii) chloride Chemical compound Cl[Pr](Cl)Cl LHBNLZDGIPPZLL-UHFFFAOYSA-K 0.000 description 5
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 238000005201 scrubbing Methods 0.000 description 4
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 4
- GTJOHISYCKPIMT-UHFFFAOYSA-N 2-methylundecane Chemical compound CCCCCCCCCC(C)C GTJOHISYCKPIMT-UHFFFAOYSA-N 0.000 description 3
- SGVYKUFIHHTIFL-UHFFFAOYSA-N Isobutylhexyl Natural products CCCCCCCC(C)C SGVYKUFIHHTIFL-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- QUXFOKCUIZCKGS-UHFFFAOYSA-N bis(2,4,4-trimethylpentyl)phosphinic acid Chemical compound CC(C)(C)CC(C)CP(O)(=O)CC(C)CC(C)(C)C QUXFOKCUIZCKGS-UHFFFAOYSA-N 0.000 description 3
- 239000003085 diluting agent Substances 0.000 description 3
- VKPSKYDESGTTFR-UHFFFAOYSA-N isododecane Natural products CC(C)(C)CC(C)CC(C)(C)C VKPSKYDESGTTFR-UHFFFAOYSA-N 0.000 description 3
- 238000004064 recycling Methods 0.000 description 3
- MGFUUKQPXCYIJZ-UHFFFAOYSA-N C(CCCCCCC)C(C(=O)N)(OCC(=O)O)CCCCCCCC Chemical compound C(CCCCCCC)C(C(=O)N)(OCC(=O)O)CCCCCCCC MGFUUKQPXCYIJZ-UHFFFAOYSA-N 0.000 description 2
- RGZVRADFLSQOLD-UHFFFAOYSA-N bis(2,4,4-trimethylpentyl) hydrogen phosphate Chemical compound CC(C)(C)CC(C)COP(O)(=O)OCC(C)CC(C)(C)C RGZVRADFLSQOLD-UHFFFAOYSA-N 0.000 description 2
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- STCOOQWBFONSKY-UHFFFAOYSA-N tributyl phosphate Chemical compound CCCCOP(=O)(OCCCC)OCCCC STCOOQWBFONSKY-UHFFFAOYSA-N 0.000 description 2
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 description 1
- VJLDTOPHCSPHKF-UHFFFAOYSA-N 2-(2-amino-2-oxoethoxy)-2-octyldecanoic acid Chemical compound CCCCCCCCC(C(O)=O)(OCC(N)=O)CCCCCCCC VJLDTOPHCSPHKF-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910052691 Erbium Inorganic materials 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910052689 Holmium Inorganic materials 0.000 description 1
- 229910052765 Lutetium Inorganic materials 0.000 description 1
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- SEGLCEQVOFDUPX-UHFFFAOYSA-N di-(2-ethylhexyl)phosphoric acid Chemical compound CCCCC(CC)COP(O)(=O)OCC(CC)CCCC SEGLCEQVOFDUPX-UHFFFAOYSA-N 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 235000019329 dioctyl sodium sulphosuccinate Nutrition 0.000 description 1
- YHAIUSTWZPMYGG-UHFFFAOYSA-L disodium;2,2-dioctyl-3-sulfobutanedioate Chemical compound [Na+].[Na+].CCCCCCCCC(C([O-])=O)(C(C([O-])=O)S(O)(=O)=O)CCCCCCCC YHAIUSTWZPMYGG-UHFFFAOYSA-L 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 239000003350 kerosene Substances 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000000622 liquid--liquid extraction Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
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- SNMVRZFUUCLYTO-UHFFFAOYSA-N n-propyl chloride Chemical compound CCCCl SNMVRZFUUCLYTO-UHFFFAOYSA-N 0.000 description 1
- 125000002347 octyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- 150000003014 phosphoric acid esters Chemical class 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000000956 solid--liquid extraction Methods 0.000 description 1
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- 229910052727 yttrium Inorganic materials 0.000 description 1
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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Description
本発明は、希土類元素、特に軽希土類元素（Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ）の中の少なくとも２種以上、又は該軽希土類元素の中の少なくとも１種以上とそれ以外の希土類元素（Ｙを含む）の少なくとも１種以上を抽出・分離する方法に関する。 The present invention provides at least two or more rare earth elements, particularly light rare earth elements (La, Ce, Pr, Nd, Sm, Eu), or at least one of the light rare earth elements and other rare earth elements. The present invention relates to a method for extracting and separating at least one of (including Y).
近年、Ｎｄ磁石を代表とする希土類磁石は、ハードディスク用やエアコン用、ハイブリッド車等に使用される各種モーターやセンサー等に広く使用されるようになっている。
しかし、希土類磁石の原料である希土類元素の現状は、その産出国がほぼ限定されており、近い将来需要が供給を上回ることも予想され、資源的な危機が叫ばれている。そこで、希土類磁石の生産時に発生する磁石粉末や屑及び不良スクラップ、更には市中より回収された製品から有価物である希土類元素の再生（リサイクル）、新たな希土類鉱床の探査や開発が強く求められている。
In recent years, rare earth magnets typified by Nd magnets are widely used in various motors and sensors used in hard disks, air conditioners, hybrid vehicles, and the like.
However, the current state of rare earth elements, which are raw materials for rare earth magnets, is almost limited in their producing countries, and it is expected that demand will exceed supply in the near future. Therefore, there is a strong demand for magnet powder, scraps and defective scrap generated during the production of rare earth magnets, as well as for the recycling (recycling) of valuable rare earth elements from products collected from the city, exploration and development of new rare earth deposits. It has been.
希土類磁石に用いられる希土類元素は、セリウム（Ｃｅ）、プラセオジム（Ｐｒ）、ネオジム（Ｎｄ）、サマリウム（Ｓｍ）、テルビウム（Ｔｂ）、ジスプロシウム（Ｄｙ）等が挙げられるが、これら希土類元素の分離には、イオン交換樹脂法（固−液抽出法）や溶媒抽出法（液−液抽出法）が知られている。工業的な希土類元素の精製分離には、連続的な工程により効率的に大量処理が可能であるため、主に溶媒抽出法が用いられている。
溶媒抽出法とは、分離を目的とする金属元素を含む水溶液からなる水相と特定の金属元素を抽出する抽出剤及びそれを希釈するための有機溶媒からなる有機相を接触させることで、金属元素を抽出剤に抽出させて分離する方法である。
Examples of rare earth elements used in rare earth magnets include cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), terbium (Tb), dysprosium (Dy), and the like. Known ion exchange resin methods (solid-liquid extraction methods) and solvent extraction methods (liquid-liquid extraction methods). In industrial refining and separation of rare earth elements, a solvent extraction method is mainly used because large-scale processing can be efficiently performed by a continuous process.
The solvent extraction method is a method in which an aqueous phase composed of an aqueous solution containing a metal element intended for separation is brought into contact with an organic phase composed of an extractant for extracting a specific metal element and an organic solvent for diluting it. In this method, an element is extracted by an extractant and separated.
従来、その抽出剤としてはＴＢＰ（燐酸トリブチル）、カルボン酸（バーサティックアシッド１０）、燐酸エステル、ホスホン酸化合物、ホスフィン酸化合物等が用いられている。例えば、燐酸エステルとしてはジ−２−エチルヘキシルリン酸［ｄｉ−２−ｅｔｈｙｌｈｅｘｙｌ−ｐｈｏｓｐｈｏｒｉｃ−ａｃｉｄ（Ｄ２ＥＨＰＡ）］等が使用され、ホスホン酸化合物としては２−エチルヘキシルリン酸モノ−２−エチルヘキシルエステル［２−ｅｔｈｙｌｈｅｘｙｌ−ｐｈｏｓｐｈｏｒｉｃ ａｃｉｄ−ｍｏｎｏ−２−ｅｔｈｙｌｈｅｘｙｌ ｅｓｔｅｒ（ＰＣ−８８Ａ：大八化学工業社製商品名）］等が使用され、ホスフィン酸化合物としてはビス（２，４，４−トリメチルペンチル）リン酸［ｂｉｓ（２，４，４−ｔｒｉｍｅｔｈｙｌｐｅｎｔｙｌ）ｐｈｏｓｐｈｏｒｉｃ ａｃｉｄ（Ｃｙａｎｅｘ２７２：Ａｍｅｒｉｃａｎ Ｃｙａｎａｍｉｄ社製商品名］等が市販され、一般的に使用されている。 Conventionally, TBP (tributyl phosphate), carboxylic acid (versaic acid 10), phosphoric acid ester, phosphonic acid compound, phosphinic acid compound, and the like are used as the extractant. For example, di-2-ethylhexyl-phosphoric acid (D2EHPA) or the like is used as the phosphate ester, and 2-ethylhexyl phosphate mono-2-ethylhexyl ester [2 -Ethylhexyl-phosphoric acid-mono-2-ethylhexyl ester (PC-88A: trade name, manufactured by Daihachi Chemical Industry Co., Ltd.)] and the like, and bis (2,4,4-trimethylpentyl) phosphoric acid as the phosphinic acid compound [Bis (2,4,4-trimethylpentyl) phosphoric acid (Cyanex 272: product name manufactured by American Cyanamid Co., Ltd.] and the like are commercially available and generally used.
溶媒抽出法の分離効率は、抽出剤の性能、特に分離係数によって決まる。即ち、分離係数が大きいほど溶媒抽出法の分離効率は高くなり、分離工程の簡略化、分離設備の小規模化となり、結果的に工程の効率化及びコストダウンに繋がる。一方、分離係数が小さいと、分離工程が複雑となり、更に分離設備が大規模となってしまう。 The separation efficiency of the solvent extraction method depends on the performance of the extractant, particularly the separation factor. That is, the larger the separation factor, the higher the separation efficiency of the solvent extraction method, and the simplification of the separation process and the reduction in the size of the separation equipment, resulting in process efficiency and cost reduction. On the other hand, if the separation factor is small, the separation process becomes complicated and the separation equipment becomes large.
現在、市販され実用化されている抽出剤のうちで希土類元素に対する分離係数が大きいと言われるＰＣ−８８Ａでも、隣接した元素間の分離係数は小さく、例えば、希土類元素の中でも最も分離が困難とも言われるネオジム／プラセオジムの分離係数は２より小さく、約１．４である。この分離係数は、ネオジム／プラセオジムを分離するために十分なものではなく、それらを十分な純度で分離するためには、大規模な設備が必要となり、多大なコストがかかることになる。そのため、これら元素を精製・分離する際には、従来よりも分離係数の大きな抽出剤及び抽出・分離方法の開発が待望されている。 Currently, PC-88A, which is said to have a large separation coefficient for rare earth elements among commercially available extractants, has a small separation coefficient between adjacent elements. For example, it may be the most difficult separation among rare earth elements. The neodymium / praseodymium separation factor referred to is less than 2 and about 1.4. This separation factor is not sufficient for separating neodymium / praseodymium, and in order to separate them with sufficient purity, a large-scale facility is required and a large cost is required. Therefore, when these elements are refined and separated, the development of an extractant and an extraction / separation method having a larger separation factor than before has been awaited.
希土類元素、特に軽希土類元素であるランタン（Ｌａ）、セリウム（Ｃｅ）、プラセオジム（Ｐｒ）、ネオジム（Ｎｄ）、サマリウム（Ｓｍ）に対し分離係数の大きな抽出剤としては、ジグリコールアミド酸が知られている（特許文献１：特開２００７−３２７０８５号公報）。その抽出剤を用いて溶媒抽出を行うことにより、希土類元素、特に軽希土類元素の抽出・分離工程は、効率化を図ることができる。しかし、ジグリコールアミド酸は、市販、実用化されているＤ２ＥＨＰＡ、ＰＣ−８８Ａ、Ｃｙａｎｅｘ２７２と化学的性質が異なることから、実用化されるべき様々な条件が見出されておらず、工業化に至っていない。 Diglycolamide acid is known as an extractant having a large separation factor for lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and samarium (Sm), which are rare earth elements, particularly light rare earth elements. (Patent Document 1: Japanese Patent Application Laid-Open No. 2007-327085). By performing solvent extraction using the extractant, the extraction / separation process of rare earth elements, particularly light rare earth elements, can be made more efficient. However, since diglycolamide acid has different chemical properties from commercially available and practically used D2EHPA, PC-88A, and Cyanex272, various conditions to be put into practical use have not been found, leading to industrialization. Not in.
本発明は、上記した問題を解決した希土類元素の抽出・分離方法を提供するもので、従来の抽出・分離方法より、希土類元素、特にネオジム／プラセオジムのように隣接した希土類元素を良好に抽出・分離することができる希土類元素の抽出・分離方法を提供することを目的とする。 The present invention provides a method for extracting / separating rare earth elements that solves the above-mentioned problems, and can extract rare earth elements, particularly adjacent rare earth elements such as neodymium / praseodymium, better than conventional extraction / separation methods. An object of the present invention is to provide a method for extracting and separating rare earth elements that can be separated.
本発明者らは、上記課題を解決するため鋭意検討を重ねた結果、ジグリコールアミド酸を抽出剤として含有する有機相と、抽出すべき希土類元素を含む水溶液である水相を、向流多段ミキサーセトラー等を用いて接触させることにより、特定の希土類元素を該有機相に抽出し、その後、該有機相を酸水溶液にて逆抽出することで選択的に特定の希土類元素を分離し、更に特定の希土類元素を分離した後の該有機相を洗浄することで、希土類元素、特にネオジム／プラセオジムのように隣接した軽希土類元素に対し良好な分離性能を持つという希土類元素の抽出・分離方法を見出し、この方法が、多種の希土類元素混合物から、特定の希土類元素を選択的に分離するに際し有効であることを知見し、本発明をなすに至った。 As a result of intensive studies in order to solve the above problems, the present inventors have developed an organic phase containing diglycolamide acid as an extractant and an aqueous phase which is an aqueous solution containing a rare earth element to be extracted in a countercurrent multistage. A specific rare earth element is extracted into the organic phase by contacting with a mixer settler or the like, and then the organic phase is selectively extracted with an aqueous acid solution to selectively separate the specific rare earth element. A method for extracting and separating rare earth elements that has a good separation performance for rare earth elements, particularly light rare earth elements adjacent to each other, such as neodymium / praseodymium, by washing the organic phase after separating the specific rare earth elements. The present inventors have found that this method is effective in selectively separating a specific rare earth element from a mixture of various rare earth elements, and have made the present invention.
即ち、本発明は、前記問題を解決する方法として、下記の希土類元素の抽出・分離方法を提供する。
請求項１：
下記一般式（１）
（式中、Ｒ1及びＲ2は、互いに同一又は異種のアルキル基であり、少なくとも一方は炭素数６以上の直鎖又は分岐鎖状のアルキル基を示す。）
で表されるジグリコールアミド酸を抽出剤として含有する有機相と、２種以上の希土類元素を含む水溶液からなる水相とをｐＨ３以下の酸性条件下で接触させることにより、前記希土類元素のうち抽出すべき希土類元素を前記有機相に抽出し、その後この有機相を酸水溶液にて逆抽出することで前記有機相に抽出した希土類元素を回収すると共に、前記有機相に抽出されずに前記水相中に残留した希土類元素を回収する希土類元素の抽出・分離方法であって、前記逆抽出を行って有機相中に含まれていた希土類元素を分離した後の有機相を水又はｐＨ３〜７の酸水溶液で洗浄し、この洗浄した有機相を前記抽出処理に再使用することを特徴とする希土類元素の抽出・分離方法。
請求項２：
抽出及び逆抽出処理を向流多段ミキサーセトラーによって行うことを特徴とする請求項１記載の希土類元素の抽出・分離方法。
請求項３：
有機相と水相とを有機相に用いた溶媒の引火点より低い温度で接触させることを特徴とする請求項１又は２記載の希土類元素の抽出・分離方法。
請求項４：
水相に含まれる抽出・分離すべき希土類元素が、Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ及びＥｕから選ばれる軽希土類元素の中の少なくとも２種、又は前記軽希土類元素の中の少なくとも１種とそれ以外のＹを含む希土類元素の中の少なくとも１種とであることを特徴とする請求項１〜３のいずれか１項記載の希土類元素の抽出・分離方法。
請求項５：
水相に含まれる希土類元素が、Ｎｄ及びＰｒであり、Ｎｄを有機相に抽出すると共に、Ｐｒを水相に残留させることによりＮｄとＰｒとを分離するようにしたことを特徴とする請求項１〜３のいずれか１項記載の希土類元素の抽出・分離方法。
請求項６：
水相に含まれる希土類元素濃度ＣAが、０．０１ｍｏｌ／Ｌ≦ＣA≦０．７ｍｏｌ／Ｌであることを特徴とする請求項１〜５のいずれか１項記載の希土類元素の抽出・分離方法。
That is, the present invention provides the following rare earth element extraction / separation method as a method for solving the above problems.
Claim 1:
The following general formula (1)
(In the formula, R 1 and R 2 are the same or different alkyl groups, and at least one of them represents a linear or branched alkyl group having 6 or more carbon atoms.)
Of the rare earth elements by contacting an organic phase containing diglycolamide acid represented by the formula (1) with an aqueous phase comprising an aqueous solution containing two or more rare earth elements under acidic conditions of
Claim 2:
2. The method for extracting and separating rare earth elements according to
Claim 3:
3. The method for extracting and separating rare earth elements according to claim 1 or 2, wherein the organic phase and the aqueous phase are contacted at a temperature lower than the flash point of the solvent used in the organic phase.
Claim 4:
The rare earth element to be extracted and separated contained in the aqueous phase is at least two kinds of light rare earth elements selected from La, Ce, Pr, Nd, Sm and Eu, or at least one kind of the light rare earth elements. The method for extracting and separating rare earth elements according to any one of
Claim 5:
The rare earth element contained in the aqueous phase is Nd and Pr, and Nd is extracted into an organic phase and Pr is left in the aqueous phase to separate Nd and Pr. The method for extracting and separating rare earth elements according to any one of 1 to 3.
Claim 6:
Rare earth element concentration C A contained in the aqueous phase, extraction and rare earth elements of any one of
本発明の抽出剤・抽出溶剤を用いた抽出方法は分離係数が大きく、分離効率よく、軽希土類元素を抽出・分離できるので初期投資が抑えられ、工業的利用価値が大きい。 The extraction method using the extractant / extraction solvent of the present invention has a large separation factor, and can extract and separate light rare earth elements with high separation efficiency, so that the initial investment is suppressed and the industrial utility value is great.
本発明において、抽出剤としては、下記一般式（１）
で表されるジグリコールアミド酸を用いる。
In the present invention, as the extractant, the following general formula (1)
The diglycol amide acid represented by these is used.
ここで、Ｒ1及びＲ2は、互いに同一又は異種のアルキル基であるが、少なくとも一方は、炭素数６以上、好ましくは６〜１８、より好ましくは７〜１２の直鎖又は分岐鎖状のアルキル基である。炭素数が６未満の場合、親油性が十分でないため、有機相の安定性に欠くことになり、水相との分相性が不良となるばかりか、抽出剤自身の水相への溶解が無視できなくなり、抽出剤の役割を果たすことができない。また、炭素数が過剰に大きい場合には、その抽出剤の製造コストが高くなるにも拘わらず、基本性能である抽出能、分離能そのものの向上には寄与しない。なお、Ｒ1及びＲ2については、親油性が確保されるのであれば、一方が炭素数６以上であれば他方は６未満であってもよい。例えば、より好適なものとして、２つのオクチル基（−Ｃ8Ｈ17）を導入した化合物、Ｎ，Ｎ−ジオクチル−３−オキサペンタン−１，５−アミド酸：ジオクチルジグリコールアミド酸［Ｎ，Ｎ−ジオクチル−３−オキサペンタン−１，５−アミッド酸：ジオクチルジグリコールアミッド酸（Ｎ，Ｎ−ｄｉｏｃｔｙｌ−３−ｏｘａｐｅｎｔａｎｅ−１，５−ａｍｉｃａｃｉｄ：ｄｉｏｃｔｙｌｄｉｇｌｙｃｏｌａｍｉｃａｃｉｄ、以下ＤＯＤＧＡＡと称する）］が挙げられる。 Here, R 1 and R 2 are the same or different alkyl groups, but at least one of them is a straight or branched chain having 6 or more carbon atoms, preferably 6 to 18, more preferably 7 to 12 carbon atoms. It is an alkyl group. If the number of carbon atoms is less than 6, the lipophilicity is not sufficient, so the stability of the organic phase is lacking, the phase separation with the aqueous phase becomes poor, and the dissolution of the extractant itself in the aqueous phase is ignored. Can no longer function as an extractant. In addition, when the carbon number is excessively large, it does not contribute to the improvement of the extraction performance and separation performance itself, which are basic performances, although the production cost of the extraction agent becomes high. As for R 1 and R 2, if the lipophilicity is secured, the other may be less than 6 as long as one is 6 or more carbon atoms. For example, a compound having two octyl groups (—C 8 H 17 ) introduced therein, N, N-dioctyl-3-oxapentane-1,5-amidic acid: dioctyl diglycolamidic acid [N, N-dioctyl-3-oxapentane-1,5-amidic acid: dioctyl diglycolamidic acid (N, N-dioctyl-3-oxapentane-1,5-amicacid: dioctyldiglycolamic acid, hereinafter referred to as DODGAA)].
通常の有機相は、抽出剤とその抽出剤を溶解可能な希釈剤である有機溶媒からなる。その有機溶媒は、水への溶解度が低く、適度な抽出剤への溶解度を持ち、比重が軽く、更に抽出能力が向上するのに適したものが選択される。例えば、トルエン、キシレン、ヘキサン、イソドデカン、ケロシン及び高級アルコール等が挙げられる。 The normal organic phase consists of an extractant and an organic solvent that is a diluent capable of dissolving the extractant. The organic solvent is selected so as to have low solubility in water, moderate solubility in an extractant, a low specific gravity, and an improvement in extraction ability. For example, toluene, xylene, hexane, isododecane, kerosene, higher alcohol and the like can be mentioned.
本発明の有機相は、上記ジグリコールアミド酸と、ジグリコールアミド酸を溶解可能な有機溶媒からなる。それを用いることで、実操業上の希土類水溶液濃度の処理が可能である。 The organic phase of the present invention comprises the diglycolamide acid and an organic solvent capable of dissolving the diglycolamide acid. By using it, it is possible to treat rare earth aqueous solution concentration in actual operation.
本発明の有機相中の抽出剤濃度ＣOは、０．１ｍｏｌ／Ｌ≦ＣO≦１．５ｍｏｌ／Ｌであることが好ましい。ＣO＜０．１ｍｏｌ／Ｌの場合、抽出剤濃度が低すぎるため、実操業上の希土類水溶液中の希土類元素濃度の処理が不可となり、実際、０．０５ｍｏｌ／Ｌ以下の濃度の希土類水溶液しか処理できないため、効率的でなく、結果的に分離設備の大規模化を招き、コスト高となってしまうおそれがある。また、そもそも希釈剤に対するジグリコールアミド酸自身の溶解度により、抽出剤濃度ＣO＞１．５ｍｏｌ／Ｌとするのは困難であり、エントレーナーとなるべき溶媒やジオクチルスルホコハク酸ナトリウム等の界面活性剤の添加が必要となり、安定した操業を制御する条件がより複雑化するおそれがある。そのため、効率的な抽出・分離を行うための有機相中の抽出剤濃度ＣOとして、好ましくは０．２ｍｏｌ／Ｌ≦ＣO≦１．０ｍｏｌ／Ｌである。 The extractant concentration C O in the organic phase of the present invention is preferably 0.1 mol / L ≦ C O ≦ 1.5 mol / L. In the case of C O <0.1 mol / L, the extractant concentration is too low, which makes it impossible to process the rare earth element concentration in the rare earth aqueous solution in actual operation. In fact, the rare earth aqueous solution having a concentration of 0.05 mol / L or less Since it cannot be processed, it is not efficient, resulting in an increase in the scale of the separation equipment, which may increase the cost. Furthermore, it is difficult to make the extractant concentration C O > 1.5 mol / L due to the solubility of diglycolamide acid itself in the diluent in the first place, and a solvent such as an entrainer or a surfactant such as sodium dioctylsulfosuccinate. Therefore, conditions for controlling stable operation may become more complicated. Therefore, the extractant concentration C O in the organic phase for efficient extraction / separation is preferably 0.2 mol / L ≦ C O ≦ 1.0 mol / L.
一方、上記抽出剤によって抽出すべき希土類元素は、水溶液として水相中に含まれる。この場合、希土類元素は、水溶性塩、例えば塩化物（ＰｒＣｌ3，ＮｄＣｌ3等）などの形態で使用することができる。 On the other hand, the rare earth element to be extracted by the extractant is contained in the aqueous phase as an aqueous solution. In this case, the rare earth element can be used in the form of a water-soluble salt such as a chloride (PrCl 3 , NdCl 3, etc.).
本発明に用いる抽出剤のジグリコールアミド酸の中でも、特にＤＯＤＧＡＡは、軽希土類元素における分離性、軽希土類元素とそれ以外の希土類元素の分離性は非常に優れている。しかし、軽希土類元素以外、即ち、重希土類元素における分離性は、市販、実用化されているＤ２ＥＨＰＡ、ＰＣ−８８Ａ、Ｃｙａｎｅｘ２７２に比べ劣るため、本発明の水相に含まれる抽出・分離する希土類元素は、軽希土類元素（Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ）の中の少なくとも２種以上、又は、軽希土類元素の少なくとも１種以上とそれ以外の希土類元素（Ｙを含む）の少なくとも１種以上からなることが好ましい。なお、前記それ以外のＹを含む希土類元素としては、Ｙ，Ｇｄ，Ｔｂ，Ｄｙ，Ｈｏ，Ｅｒ，Ｔｍ，Ｙｂ，Ｌｕ等が挙げられる。
この場合、本発明においては、特定の希土類元素を前記有機相に抽出し得るもので、例えばＮｄとＰｒとの抽出・分離においては、Ｎｄが優先的に有機相に抽出されるものである。
Among the diglycolamide acids of the extractant used in the present invention, DODGAA is particularly excellent in separability in light rare earth elements and separability between light rare earth elements and other rare earth elements. However, separability in light rare earth elements, that is, heavy rare earth elements, is inferior to D2EHPA, PC-88A, and Cyanex272, which are commercially available and put to practical use. Is at least two of light rare earth elements (La, Ce, Pr, Nd, Sm, Eu), or at least one of light rare earth elements and other rare earth elements (including Y). It is preferable to consist of more than seeds. Examples of other rare earth elements containing Y include Y, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
In this case, in the present invention, a specific rare earth element can be extracted into the organic phase. For example, in the extraction / separation of Nd and Pr, Nd is preferentially extracted into the organic phase.
溶媒抽出における希土類元素の抽出のし易さは、そのイオン半径に依存し、更に、抽出される元素のうち、イオン半径が小さいものが有機相に抽出される。そのため、例えば、隣り合う２つの軽希土類元素を抽出した場合、下記の通りとなる。
組み合わせ 有機相に抽出される元素
Ｌａ／Ｃｅ Ｃｅ
Ｃｅ／Ｐｒ Ｐｒ
Ｐｒ／Ｎｄ Ｎｄ
Ｎｄ／Ｓｍ Ｓｍ
Ｓｍ／Ｅｕ Ｅｕ
The ease of extraction of the rare earth element in the solvent extraction depends on its ionic radius, and among the extracted elements, those having a small ionic radius are extracted into the organic phase. Therefore, for example, when two adjacent light rare earth elements are extracted, the result is as follows.
Element La / Ce Ce extracted in combined organic phase
Ce / Pr Pr
Pr / Nd Nd
Nd / Sm Sm
Sm / Eu Eu
水相に含まれる希土類元素濃度ＣAは、０．０１ｍｏｌ／Ｌ≦ＣA≦０．７ｍｏｌ／Ｌであることが好ましい。ＣA＜０．０１ｍｏｌ／Ｌの場合、抽出・分離における抽出能、分離能そのものには問題はないが、希土類元素濃度ＣAが希薄であるため、十分な量の目的物（希土類元素）を得るためには大量の水相が必要となる。その結果、分離設備の大規模化を招き、コスト高を招いてしまうおそれがある。ＣA＞０．７ｍｏｌ／Ｌの場合、抽出すべき希土類元素濃度につりあう有機相のジグリコールアミド酸濃度を得ることは困難であり、結果、希土類元素濃度に対し抽出剤であるジグリコールアミド酸が十分でないため、有機相の凝固が起こり溶媒抽出による分離精製ができないおそれがある。 The rare earth element concentration C A contained in the aqueous phase is preferably 0.01 mol / L ≦ C A ≦ 0.7 mol / L. In the case of C A <0.01 mol / L, there is no problem in the extraction ability and separation ability itself in the extraction / separation, but since the rare earth element concentration C A is dilute, a sufficient amount of the target substance (rare earth element) can be obtained. A large amount of aqueous phase is required to obtain. As a result, the scale of the separation facility is increased, which may increase the cost. When C A > 0.7 mol / L, it is difficult to obtain a diglycolamide acid concentration in the organic phase that matches the rare earth element concentration to be extracted. Is not sufficient, the organic phase may coagulate and may not be separated and purified by solvent extraction.
ここで、本発明においては、有機相中の抽出剤濃度ＣO、水相中の希土類元素濃度ＣAの比率Ｃ0／ＣAを２≦Ｃ0／ＣA≦１０とすることが好ましい。比率Ｃ0／ＣA＜２であると、希土類元素濃度に対し抽出剤であるジグリコールアミド酸濃度が十分でないため、有機相の凝固が起こり、溶媒抽出による分離精製ができないおそれがある。また、比率Ｃ0／ＣA＞１０であると、基本性能である抽出能、分離能そのものの向上には寄与しないが、水相濃度に対し有機相濃度が高すぎるためコスト高となる。 Here, in the present invention, the ratio C 0 / C A of the extractant concentration C O in the organic phase and the rare earth element concentration C A in the aqueous phase is preferably 2 ≦ C 0 / C A ≦ 10. If the ratio C 0 / C A <2, the concentration of diglycolamide acid as the extractant is not sufficient with respect to the rare earth element concentration, so that the organic phase may coagulate and separation and purification by solvent extraction may not be possible. Further, if the ratio C 0 / C A > 10, it does not contribute to improvement of the basic performance, ie, extraction ability and separation ability itself, but the cost becomes high because the organic phase concentration is too high with respect to the aqueous phase concentration.
また、抽出工程時の抽出層（有機相・水相）のｐＨは３以下に制御する。ｐＨが３を超えると希土類元素が希土類水酸化物を形成し沈殿物となってしまうため、有機相と水相を接触させる際、抽出・分離が不可となってしまう。結果、分相不良が起こり、抽出工程に問題が発生する。また、ｐＨが強酸の場合、平衡酸濃度を調整する際に使用する塩基等の使用量が多くなるため好ましくなく、抽出工程時の抽出層（有機相・水相）のｐＨは好ましくは１〜３である。 Further, the pH of the extraction layer (organic phase / aqueous phase) during the extraction step is controlled to 3 or less. If the pH exceeds 3, the rare earth element forms a rare earth hydroxide and becomes a precipitate, so that extraction / separation becomes impossible when the organic phase and the aqueous phase are brought into contact with each other. As a result, phase separation failure occurs and a problem occurs in the extraction process. In addition, when the pH is a strong acid, it is not preferable because the amount of a base used when adjusting the equilibrium acid concentration increases, and the pH of the extraction layer (organic phase / aqueous phase) during the extraction step is preferably 1 to 1. 3.
更に、抽出工程時の抽出層（有機相・水相）の温度は、有機相を構成する溶媒の引火点以下に制御する。その温度は、より高いほうが有機相への抽出剤の溶解度が高くなり、有機相−水相の分離が良好となるが、引火点による火災を防止するため、用いる溶媒の引火点を超えないことが必要であり、引火点−（５〜１０）℃で制御することが好ましい。 Furthermore, the temperature of the extraction layer (organic phase / aqueous phase) during the extraction step is controlled to be equal to or lower than the flash point of the solvent constituting the organic phase. The higher the temperature, the higher the solubility of the extractant in the organic phase and the better the separation of the organic and aqueous phases, but to prevent fires from the flash point, do not exceed the flash point of the solvent used. Is necessary, and the flash point is preferably controlled at − (5 to 10) ° C.
本発明において、抽出剤・希釈剤からなる有機相と、分離すべき希土類元素を含む水溶液とを効率よく接触させ、効率的な抽出・分離を行うために図１に示すような向流多段ミキサーセトラーを用いることができる。
図１において、Ａは抽出部、Ｂはスクラブ部、Ｃは逆抽出部でそれぞれの段数は適宜設定される。１〜８はミキサーセトラーへの流入、又は流出する流れを示し、配管である。１より希土類元素溶液、２より抽出剤を含有する有機相、３より水酸化ナトリウム水溶液等のアルカリ水溶液、４，６より塩酸水溶液等の酸水溶液を導入し、５より有機相に抽出されずに残留した希土類元素を含む水相、７より有機相に抽出された希土類元素を逆抽出した水溶液を回収する。抽出部Ａにおいては水相のｐＨを希土類元素の種類に応じて調整し、希土類元素を有機相と水相に分離する。スクラブ部Ｂにおいては、有機相中に少量溶解している水相に残留すべき希土類元素だけを選択的に抽出する酸水溶液を用いて、有機相を洗浄する。逆抽出部Ｃにおいては、有機相に抽出された希土類元素を酸水溶液中に逆抽出する。また８より希土類元素を逆抽出した抽出剤を循環させ再利用することができる。
In the present invention, in order to efficiently contact an organic phase composed of an extractant / diluent and an aqueous solution containing a rare earth element to be separated for efficient extraction / separation, a countercurrent multistage mixer as shown in FIG. A settler can be used.
In FIG. 1, A is an extraction unit, B is a scrubbing unit, C is a back extraction unit, and the number of stages is set as appropriate.
この場合、抽出部Ａにおいて、希土類元素溶液１と抽出剤を含有する有機相２とを接触させて抽出を行い、希土類元素溶液１中の特定の希土類元素を有機相２に抽出し、有機相２に抽出されずに残った希土類元素を含む水相５を抽出部Ａより排出、回収する。なお、アルカリ水溶液３は平衡酸濃度調整の目的で導入するものである。上記特定の希土類元素を抽出した有機相２はスクラブ部Ｂに導入され、ここで有機相２中に少量溶解している水相に残るべき希土類元素だけを選択的に抽出するようにｐＨ調整された酸水溶液４（例えば、Ｎｄ／Ｐｒの抽出・分離の場合、ｐＨを１〜２に調整することによりＰｒが選択的に分離される）を用いて有機相２を洗浄し、上記水相に残るべき希土類元素だけを選択的に抽出した酸水溶液４は、抽出部Ａに導入されると共に、洗浄された有機相２は、逆抽出部Ｃに導入され、ここで有機相２中の希土類元素を所用のｐＨに調整された酸水溶液６により逆抽出し、得られた希土類元素を含む水溶液７を排出、回収する。希土類元素が逆抽出された有機相２（８）は抽出部Ａに循環することができる。
In this case, in the extraction part A, the rare
しかし、本発明のジグリコールアミド酸を抽出剤とした有機相の場合、希土類元素を酸水溶液中に逆抽出した後の有機相をそのまま循環させ、これを続けると、有機相に残留した酸が抽出部にて接触する水相のｐＨを低下させる、もしくは、有機相中の抽出剤に酸が抽出されることで抽出部にて抽出されるべき希土類元素の抽出を妨げることにより、安定した抽出・分離ができないおそれが生じる。これは、有機相を循環させる構造を持つ向流多段ミキサーセトラーにとって問題となる場合がある。
そこで、有機相の循環利用を有効に行う方法として、逆抽出部から流出した有機相を、抽出部に循環させる前段階として、水又はｐＨ３〜７（３以上７未満）の酸水溶液で洗浄する洗浄部を設ける。逆抽出後の有機相を水又はｐＨ３〜７（３以上７未満）の酸水溶液で洗浄することにより、有機相に残留した酸を洗い流す、もしくは、有機相の抽出剤に抽出された酸を放出させることができるため、循環後の抽出部のｐＨの変動を抑え、かつ、抽出されるべき希土類元素の抽出を妨げないことから、効率よく抽出・分離が行われることとなる。
However, in the case of the organic phase using the diglycolamide acid of the present invention as an extractant, the organic phase after back extraction of the rare earth element into the acid aqueous solution is circulated as it is, and if this is continued, the acid remaining in the organic phase will be recovered. Stable extraction by lowering the pH of the aqueous phase in contact with the extraction part or by preventing the extraction of rare earth elements to be extracted in the extraction part by extracting acid to the extractant in the organic phase・ Possibility of separation is not possible. This can be a problem for countercurrent multistage mixer settlers with a structure that circulates the organic phase.
Therefore, as a method for effectively recycling the organic phase, the organic phase flowing out from the back extraction unit is washed with water or an acid aqueous solution having a pH of 3 to 7 (less than 3 and less than 7) as a pre-stage for circulation to the extraction unit. Provide a cleaning section. By washing the organic phase after back extraction with water or an acid aqueous solution having a pH of 3 to 7 (3 or more and less than 7), the acid remaining in the organic phase is washed away, or the acid extracted into the organic phase extractant is released. Therefore, since the fluctuation of the pH of the extraction part after the circulation is suppressed and the extraction of the rare earth element to be extracted is not hindered, the extraction / separation is performed efficiently.
このような方法を効果的に行う装置として、図２に示す向流多段ミキサーセトラーを用いることができる。ここで、符号Ａ，Ｂ，Ｃ及び１〜８は図１と同様で、図１で説明した場合と同様にして抽出、逆抽出が行われる。
図２の向流多段ミキサーセトラーは、図１の装置において、洗浄部Ｄを付設したもので、希土類が逆抽出されて逆抽出部Ｃから排出された有機相８は、洗浄部Ｄに導入され、ここで洗浄用の水又は酸水溶液９により洗浄され、洗浄後の有機相８は抽出部Ａに導入され、循環使用される。
なお、洗浄部で用いられた水又はｐＨ３〜７（３以上７未満）の酸水溶液は、必要に応じてｐＨ調整した後、スクラブ部Ｂの酸溶液として再利用することができる。
As an apparatus for effectively carrying out such a method, a countercurrent multistage mixer settler shown in FIG. 2 can be used. Here, symbols A, B, C, and 1 to 8 are the same as those in FIG. 1, and extraction and back-extraction are performed in the same manner as in the case described in FIG.
The counter-current multistage mixer settler of FIG. 2 is provided with a cleaning unit D in the apparatus of FIG. 1, and the
The water used in the washing part or the acid aqueous solution of
本発明における洗浄部Ｄの洗浄液は、水又はｐＨ３〜７（３以上７未満）の酸水溶液である。洗浄液がｐＨ３未満の場合、有機相に残留した酸を洗い流す、もしくは、有機相の抽出剤に抽出された酸を放出させる洗浄効果が不十分となる。また、洗浄後のｐＨが７を超える場合、有機相と水相が混合後に乳化するおそれがあるため、不適である。効果的な洗浄効果を得るための洗浄部Ｄの洗浄液は、水又はｐＨ３〜７（３以上７未満）の酸水溶液であり、好ましくは水又はｐＨ５〜７（５以上７未満）の酸水溶液である。
The cleaning liquid of the cleaning part D in the present invention is water or an acid aqueous solution having a pH of 3 to 7 (3 or more and less than 7). When the cleaning solution is less than
以下、実施例と参考例と比較例を示して本発明を具体的に説明するが、本発明は下記の実施例に制限されるものではない。 EXAMPLES Hereinafter, although an Example, a reference example, and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.
［参考例１〜７、比較例１〜４］
（希土類金属の相互分離）
本発明による溶媒抽出を行う場合における、混合希土類金属の分離性能を調べる試験を行った。
ＤＯＤＧＡＡをヘキサンで溶解し、表１に示した濃度溶液を調製して有機相とした。希土類金属としてＰｒ：Ｎｄ＝１：１モル比でＰｒ＋Ｎｄの濃度が表１に示した濃度となるように塩化プラセオジムと塩化ネオジムの混合溶液を調製した。上記有機相１００ｍｌと水相１００ｍｌを分液漏斗に入れ、室温（２０℃）で約２０分間振盪し、抽出処理を行い、平衡に達した後、有機相と水相を分離した。更に、有機相１００ｍｌは５Ｎ−塩酸１００ｍｌと共に分液漏斗に入れ、２０℃で約２０分間振盪し、有機相に抽出された希土類元素を塩酸水溶液中に逆抽出した。Ｎｄ／Ｐｒ分離特性、分相性を調べた。
[ Reference Examples 1-7, Comparative Examples 1-4]
(Mutual separation of rare earth metals)
In the case of performing solvent extraction according to the present invention, a test was conducted to examine the separation performance of mixed rare earth metals.
DODGAA was dissolved in hexane to prepare a concentration solution shown in Table 1 to obtain an organic phase. As a rare earth metal, a mixed solution of praseodymium chloride and neodymium chloride was prepared so that the Pr: Nd = 1: 1 molar ratio and the Pr + Nd concentration were as shown in Table 1. 100 ml of the organic phase and 100 ml of the aqueous phase were placed in a separatory funnel, shaken at room temperature (20 ° C.) for about 20 minutes, extracted, and after reaching equilibrium, the organic and aqueous phases were separated. Further, 100 ml of the organic phase was placed in a separatory funnel together with 100 ml of 5N hydrochloric acid, and shaken at 20 ° C. for about 20 minutes, and the rare earth element extracted into the organic phase was back extracted into an aqueous hydrochloric acid solution. Nd / Pr separation characteristics and phase separation were investigated.
［比較例５］
Ｄ２ＥＨＰＡをヘキサンで溶解し、１ｍｏｌ／Ｌの溶液を調製して有機相とした。希土類金属としてＰｒ：Ｎｄ＝１：１モル比でＰｒ＋Ｎｄ＝０．３ｍｏｌ／Ｌの濃度となるように塩化プラセオジムと塩化ネオジムの混合溶液を調製した。その後、参考例１の手順によりＮｄ／Ｐｒ分離特性、分相性を調べた。
[Comparative Example 5]
D2EHPA was dissolved in hexane to prepare a 1 mol / L solution to obtain an organic phase. A mixed solution of praseodymium chloride and neodymium chloride was prepared so that the rare earth metal had a Pr: Nd = 1: 1 molar ratio and a concentration of Pr + Nd = 0.3 mol / L. Thereafter, Nd / Pr separation characteristics and phase separation were examined by the procedure of Reference Example 1.
［比較例６］
ＰＣ−８８Ａをヘキサンで溶解し、１ｍｏｌ／Ｌの溶液を調製して有機相とした。希土類金属としてＰｒ：Ｎｄ＝１：１モル比でＰｒ＋Ｎｄ＝０．３ｍｏｌ／Ｌの濃度となるように塩化プラセオジムと塩化ネオジムの混合溶液を調製した。その後、参考例１の手順によりＮｄ／Ｐｒ分離特性、分相性を調べた。
表１に、水相と逆抽出した塩酸水溶液中のプラセオジムとネオジムの濃度をＩＣＰ発光分析装置（ＩＣＰ−７５００：島津製作所（株）製商品名）で測定した結果を示す。
[Comparative Example 6]
PC-88A was dissolved in hexane to prepare a 1 mol / L solution to obtain an organic phase. A mixed solution of praseodymium chloride and neodymium chloride was prepared so that the rare earth metal had a Pr: Nd = 1: 1 molar ratio and a concentration of Pr + Nd = 0.3 mol / L. Thereafter, Nd / Pr separation characteristics and phase separation were examined by the procedure of Reference Example 1.
Table 1 shows the results of measuring the concentrations of praseodymium and neodymium in an aqueous hydrochloric acid solution back-extracted from the aqueous phase with an ICP emission analyzer (ICP-7500: trade name, manufactured by Shimadzu Corporation).
ＤＯＤＧＡＡ濃度ＣOと混合希土類元素濃度ＣAの比率３≦ＣO／ＣA≦１０、ＤＯＤＧＡＡ濃度０．１≦ＣO≦１．５である参考例１〜７は良好な結果が得られたのに対し、ＤＯＤＧＡＡ濃度と混合希土類元素濃度の比率ＣO／ＣA＜２である比較例１，３，４は有機相−水相の分離が不可、つまり分相状態として分相不良であった。また、比率ＣO／ＣA＞１０である比較例２は分相状態及び分離係数に問題はないが、水相濃度に対し有機相濃度が高すぎるため抽出剤コストが高くなり、好ましくない。
更に、ＤＯＤＧＡＡの分離特性（Ｎｄ／Ｐｒ分離特性（２．５））は、同条件のＤ２ＥＨＰＡ（Ｎｄ／Ｐｒ分離特性（１．２３））、ＰＣ−８８Ａ（Ｎｄ／Ｐｒ分離特性（１．４））と比較して大きく上回るＮｄ／Ｐｒ分離特性を示すことがわかる。
DODGAA concentration C O and
Furthermore, the separation characteristics (Nd / Pr separation characteristics (2.5)) of DODGAA are D2EHPA (Nd / Pr separation characteristics (1.23)) and PC-88A (Nd / Pr separation characteristics (1.4) under the same conditions. It can be seen that the Nd / Pr separation characteristics are significantly higher than those of ()).
［実施例１、比較例７］
本発明に従って溶媒抽出を行う場合における、ＤＯＤＧＡＡの混合軽希土類金属（Ｎｄ／Ｐｒ）の分離係数、混合重希土類金属（Ｄｙ／Ｔｂ）の分離係数を調べる試験を行った。ＤＯＤＧＡＡはヘキサン溶解し、０．３ｍｏｌ／Ｌの濃度溶液を調製して有機相とした。混合軽希土類金属濃度はプラセオジム：ネオジム＝１：１モル比でプラセオジム＋ネオジム＝０．１ｍｏｌ／Ｌの濃度溶液を調製して水相とした。混合重希土類金属濃度はテルビウム：ジスプロシウム＝１：１モル比でテルビウム＋ジスプロシウム＝０．１ｍｏｌ／Ｌの濃度溶液を調製して水相とした。上記有機相１００ｍｌと水相１００ｍｌを分液漏斗に入れ、室温（２０℃）で約２０分間振盪し、抽出処理を行い、平衡に達した後、有機相と水相を分離した。更に、有機相１００ｍｌは５Ｎ−塩酸１００ｍｌと共に分液漏斗に入れ、室温（２０℃）で約２０分間振盪し、有機相に抽出された希土類元素を塩酸水溶液中に逆抽出した。水相と逆抽出した塩酸水溶液中のプラセオジムとネオジムの濃度、テルビウムとジスプロシウムの濃度をＩＣＰ発光分析装置（ＩＣＰ−７５００：島津製作所（株）製商品名）で測定した。
また、比較例７として市販、実用化されているＰＣ−８８Ａをヘキサンで溶解し、１ｍｏｌ／Ｌの濃度に調整したものを有機相とし、混合軽希土類金属（Ｎｄ／Ｐｒ）、混合重希土類金属（Ｄｙ／Ｔｂ）の分離係数を調べた。結果を表２に示す。
[Example 1 and Comparative Example 7]
In the case of performing solvent extraction according to the present invention, a test was conducted to examine the separation factor of the mixed light rare earth metal (Nd / Pr) of DODGAA and the separation factor of the mixed heavy rare earth metal (Dy / Tb). DODGAA was dissolved in hexane to prepare a 0.3 mol / L concentration solution as an organic phase. The mixed light rare earth metal concentration was praseodymium: neodymium = 1: 1 molar ratio to prepare a concentration solution of praseodymium + neodymium = 0.1 mol / L to obtain an aqueous phase. The mixed heavy rare earth metal concentration was terbium: dysprosium = 1: 1 molar ratio, and a terbium + dysprosium = 0.1 mol / L concentration solution was prepared to obtain an aqueous phase. 100 ml of the organic phase and 100 ml of the aqueous phase were placed in a separatory funnel, shaken at room temperature (20 ° C.) for about 20 minutes, extracted, and after reaching equilibrium, the organic and aqueous phases were separated. Furthermore, 100 ml of the organic phase was placed in a separatory funnel together with 100 ml of 5N hydrochloric acid, and shaken at room temperature (20 ° C.) for about 20 minutes, and the rare earth element extracted into the organic phase was back extracted into an aqueous hydrochloric acid solution. The concentrations of praseodymium and neodymium, and the concentrations of terbium and dysprosium in the aqueous hydrochloric acid solution back-extracted with the aqueous phase were measured with an ICP emission spectrometer (ICP-7500: trade name, manufactured by Shimadzu Corporation).
Further, commercially available and practically used PC-88A as Comparative Example 7 was dissolved in hexane and adjusted to a concentration of 1 mol / L as an organic phase, and mixed light rare earth metal (Nd / Pr), mixed heavy rare earth metal The separation factor of (Dy / Tb) was examined. The results are shown in Table 2.
ＤＯＤＧＡＡの軽希土類金属（Ｎｄ／Ｐｒ）の分離係数は、市販のＰＣ−８８Ａの分離係数１．４に比べ２．５と優れた結果が得られたが、ＤＯＤＧＡＡの重希土類元素（Ｄｙ／Ｔｂ）の分離係数は、市販のＰＣ−８８Ａの分離係数２．１と比べ１．３と劣る結果となった。
この結果から、本発明の水相に含まれる抽出すべき希土類元素は、軽希土類元素（Ｌａ，Ｃｅ，Ｐｒ，Ｎｄ，Ｓｍ，Ｅｕ）の中の少なくとも２種以上、又は軽希土類元素の少なくとも１種以上とそれ以外の希土類元素（Ｙを含む）の少なくとも１種以上からなることが特に好ましいことがわかる。
The separation factor of the light rare earth metal (Nd / Pr) of DODGAA was 2.5, which was superior to the separation factor of 1.4 of the commercially available PC-88A, but the heavy rare earth element (Dy / Tb) of DODGAA was obtained. ) Was inferior to the separation factor 2.1 of the commercially available PC-88A at 1.3.
From this result, the rare earth element to be extracted contained in the aqueous phase of the present invention is at least two or more of light rare earth elements (La, Ce, Pr, Nd, Sm, Eu), or at least one of the light rare earth elements. It can be seen that it is particularly preferable to comprise at least one species or more and other rare earth elements (including Y).
［実施例２、比較例８］
０．３ｍｏｌ／ＬのＤＯＤＧＡＡイソドデカン溶液を有機相とし、ネオジム：プラセオジム＝１：１モル比でネオジム＋プラセオジム＝０．１ｍｏｌ／Ｌとなる塩化ネオジムと塩化プラセオジムの混合溶液を水相としたものによる向流多段ミキサーセトラーによるサイクル試験を行った。
図１，２において、Ａを２４段、Ｂを２４段、Ｃを８段とした向流多段ミキサーセトラーで、上記有機相と水相を混合し、イソドデカン引火点以下の４０℃で抽出させ、定常状態に達した後、各サイクルの逆抽出部Ｃの有機相を１００ｍｌ採取した。
希土類金属としてＰｒ：Ｎｄ＝１：１モル比でＰｒ＋Ｎｄ＝０．１ｍｏｌ／Ｌとなる塩化プラセオジムと塩化ネオジムの混合溶液を調製して水相とした。上記採取した有機相１００ｍｌと水相１００ｍｌを分液漏斗に入れ、室温（２０℃）で約２０分間振盪し、抽出処理を行い、平衡に達した後、有機相と水相を分離した。更に、有機相１００ｍｌは５Ｎ−塩酸１００ｍｌと共に分液漏斗に入れ、２０℃で約２０分間振盪し、有機相に抽出された希土類元素を塩酸水溶液中に逆抽出した。逆抽出されたＰｒ／Ｎｄの濃度を前記したＩＣＰ発光分析装置で測定し、初期濃度０．１ｍｏｌ／ＬのＰｒ／Ｎｄ濃度と逆抽出後のＰｒ／Ｎｄ濃度から抽出率を算出した。
図２に示す洗浄部Ｄを純水で有機相を水洗するミキサーセトラーにより試験を行ったものの結果を実施例２とし、図１に示す洗浄部Ｄのないミキサーセトラーにより試験を行ったものの結果を比較例８とした。結果を図３に示す。
洗浄部Ｄにより有機相を洗浄したものは１０サイクル経過後も良好な抽出率を示したが、洗浄部Ｄのないものは３サイクル経過後に抽出率の低下が見られ、１０サイクル経過後は１５％と十分な抽出ができなかった。
[Example 2 and Comparative Example 8]
With a 0.3 mol / L DODGAA isododecane solution as the organic phase and a mixed solution of neodymium chloride and praseodymium chloride in which the neodymium: praseodymium = 1: 1 molar ratio is neodymium + praseodymium = 0.1 mol / L. A cycle test was conducted with a countercurrent multistage mixer settler.
In FIGS. 1 and 2, the organic phase and the aqueous phase are mixed and extracted at 40 ° C. below the isododecane flash point in a countercurrent multistage mixer settler with 24 stages for A, 24 stages for B, and 8 stages for C. After reaching a steady state, 100 ml of the organic phase of the back extraction part C in each cycle was collected.
A mixed solution of praseodymium chloride and neodymium chloride with Pr: Nd = 1: 1 molar ratio as Pr + Nd = 0.1 mol / L was prepared as a rare earth metal to prepare an aqueous phase. 100 ml of the collected organic phase and 100 ml of the aqueous phase were placed in a separatory funnel, shaken at room temperature (20 ° C.) for about 20 minutes, extracted, and after reaching equilibrium, the organic and aqueous phases were separated. Further, 100 ml of the organic phase was placed in a separatory funnel together with 100 ml of 5N hydrochloric acid, and shaken at 20 ° C. for about 20 minutes, and the rare earth element extracted into the organic phase was back extracted into an aqueous hydrochloric acid solution. The concentration of back-extracted Pr / Nd was measured with the above-described ICP emission spectrometer, and the extraction rate was calculated from the Pr / Nd concentration with an initial concentration of 0.1 mol / L and the Pr / Nd concentration after back extraction.
The result of what was tested by the mixer settler which wash | cleans the organic part with the pure water for the washing | cleaning part D shown in FIG. 2 was set as Example 2, and the result of what was tested by the mixer settler without the washing | cleaning part D shown in FIG. It was set as Comparative Example 8. The results are shown in FIG.
What washed the organic phase by the washing part D showed a good extraction rate even after 10 cycles, but those without the washing part D showed a decrease in the extraction rate after 3 cycles, and 15 days after 10 cycles. % Could not be extracted sufficiently.
１ 希土類元素溶液又はこれを導入する配管
２ 抽出剤を含有する有機相又はこれを導入する配管
３ アルカリ水溶液又はこれを導入する配管
４ 酸水溶液又はこれを循環させる配管
５ 有機相に抽出されずに残留した希土類元素を含む水相又はこれを回収する配管
６ 酸水溶液又はこれを導入する配管
７ 有機相に抽出された希土類元素を逆抽出した水溶液又はこれを回収する配管
８ 有機相又はこれを循環させる配管
９ 洗浄用の水又は酸水溶液又はこれを導入する配管
Ａ 抽出部
Ｂ スクラブ部
Ｃ 逆抽出部
Ｄ 洗浄部
DESCRIPTION OF
Claims (6)
（式中、Ｒ1及びＲ2は、互いに同一又は異種のアルキル基であり、少なくとも一方は炭素数６以上の直鎖又は分岐鎖状のアルキル基を示す。）
で表されるジグリコールアミド酸を抽出剤として含有する有機相と、２種以上の希土類元素を含む水溶液からなる水相とをｐＨ３以下の酸性条件下で接触させることにより、前記希土類元素のうち抽出すべき希土類元素を前記有機相に抽出し、その後この有機相を酸水溶液にて逆抽出することで前記有機相に抽出した希土類元素を回収すると共に、前記有機相に抽出されずに前記水相中に残留した希土類元素を回収する希土類元素の抽出・分離方法であって、前記逆抽出を行って有機相中に含まれていた希土類元素を分離した後の有機相を水又はｐＨ３〜７の酸水溶液で洗浄し、この洗浄した有機相を前記抽出処理に再使用することを特徴とする希土類元素の抽出・分離方法。 The following general formula (1)
(In the formula, R 1 and R 2 are the same or different alkyl groups, and at least one of them represents a linear or branched alkyl group having 6 or more carbon atoms.)
Of the rare earth elements by contacting an organic phase containing diglycolamide acid represented by the formula (1) with an aqueous phase comprising an aqueous solution containing two or more rare earth elements under acidic conditions of pH 3 or less. The rare earth element to be extracted is extracted into the organic phase, and then the organic phase is back extracted with an aqueous acid solution to recover the rare earth element extracted into the organic phase, and the water is extracted without being extracted into the organic phase. A method for extracting and separating a rare earth element that recovers a rare earth element remaining in a phase, wherein the organic phase after separating the rare earth element contained in the organic phase by performing the back extraction is water or pH 3-7 A method for extracting and separating rare earth elements, comprising washing with an acid aqueous solution and reusing the washed organic phase for the extraction treatment.
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| JP5740227B2 (en) * | 2011-06-30 | 2015-06-24 | 株式会社東芝 | Rare metal production method |
| JP5720583B2 (en) | 2012-01-13 | 2015-05-20 | 信越化学工業株式会社 | Liquid-liquid extraction apparatus, multistage liquid-liquid extraction apparatus using the same, and multistage continuous extraction apparatus for rare earth elements |
| JP2013209689A (en) * | 2012-03-30 | 2013-10-10 | Sumitomo Heavy Ind Ltd | Method for recovering rare-earth element |
| CN102912157B (en) * | 2012-11-02 | 2013-10-23 | 广东富远稀土新材料股份有限公司 | Method for extracting and separating light rare earth |
| JP6829805B2 (en) * | 2017-03-30 | 2021-02-17 | 国立研究開発法人産業技術総合研究所 | High-precision mutual separation method for rare earth ions |
| JP7297294B2 (en) * | 2019-06-19 | 2023-06-26 | 国立研究開発法人日本原子力研究開発機構 | Method for producing specific substances by extraction and separation in a liquid-liquid system |
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| CN113584305B (en) * | 2021-07-28 | 2023-03-14 | 福建省长汀金龙稀土有限公司 | Application and method of N, N-dialkylamide carboxylic acid compounds |
| CN116065021B (en) * | 2023-02-16 | 2023-12-19 | 中国科学院广州地球化学研究所 | Ion exchange separation and purification method of single rare earth element samarium |
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