JP2023181679A - Selective separation method for hybrid double sulfate of rare earth elements - Google Patents
Selective separation method for hybrid double sulfate of rare earth elements Download PDFInfo
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- 229910052761 rare earth metal Inorganic materials 0.000 title claims abstract description 191
- 238000000926 separation method Methods 0.000 title claims description 10
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 title abstract description 21
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 296
- 238000000034 method Methods 0.000 claims abstract description 43
- 238000010828 elution Methods 0.000 claims abstract description 17
- 239000007788 liquid Substances 0.000 claims abstract description 17
- 150000003839 salts Chemical class 0.000 claims description 140
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 24
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 24
- -1 alkali metal salt Chemical class 0.000 claims description 16
- 239000007787 solid Substances 0.000 claims description 15
- 229910052783 alkali metal Inorganic materials 0.000 claims description 10
- 235000006408 oxalic acid Nutrition 0.000 claims description 8
- 238000001556 precipitation Methods 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 7
- 239000000956 alloy Substances 0.000 claims description 6
- 150000002910 rare earth metals Chemical class 0.000 claims description 6
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 5
- 239000002244 precipitate Substances 0.000 claims description 5
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 5
- 235000011152 sodium sulphate Nutrition 0.000 claims description 5
- 150000001340 alkali metals Chemical class 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 3
- 239000000243 solution Substances 0.000 description 16
- 229910052692 Dysprosium Inorganic materials 0.000 description 11
- 229910052771 Terbium Inorganic materials 0.000 description 11
- 238000004090 dissolution Methods 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- 229910052779 Neodymium Inorganic materials 0.000 description 8
- 229910052777 Praseodymium Inorganic materials 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 7
- 239000000203 mixture Substances 0.000 description 7
- 238000011084 recovery Methods 0.000 description 7
- 238000003756 stirring Methods 0.000 description 7
- 238000001914 filtration Methods 0.000 description 6
- 239000000463 material Substances 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 5
- 239000003513 alkali Substances 0.000 description 4
- 229910052936 alkali metal sulfate Inorganic materials 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 230000001376 precipitating effect Effects 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- KBQHZAAAGSGFKK-UHFFFAOYSA-N dysprosium atom Chemical compound [Dy] KBQHZAAAGSGFKK-UHFFFAOYSA-N 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000002354 inductively-coupled plasma atomic emission spectroscopy Methods 0.000 description 3
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 3
- 229910017604 nitric acid Inorganic materials 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 3
- GZCRRIHWUXGPOV-UHFFFAOYSA-N terbium atom Chemical compound [Tb] GZCRRIHWUXGPOV-UHFFFAOYSA-N 0.000 description 3
- 229910000640 Fe alloy Inorganic materials 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
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- 229910052684 Cerium Inorganic materials 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
- 229910052693 Europium Inorganic materials 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
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 1
- 229910052773 Promethium Inorganic materials 0.000 description 1
- 229910052772 Samarium Inorganic materials 0.000 description 1
- 229910052775 Thulium Inorganic materials 0.000 description 1
- 229910052769 Ytterbium Inorganic materials 0.000 description 1
- QJVKUMXDEUEQLH-UHFFFAOYSA-N [B].[Fe].[Nd] Chemical compound [B].[Fe].[Nd] QJVKUMXDEUEQLH-UHFFFAOYSA-N 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
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- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
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- 239000003480 eluent Substances 0.000 description 1
- UYAHIZSMUZPPFV-UHFFFAOYSA-N erbium Chemical compound [Er] UYAHIZSMUZPPFV-UHFFFAOYSA-N 0.000 description 1
- OGPBJKLSAFTDLK-UHFFFAOYSA-N europium atom Chemical compound [Eu] OGPBJKLSAFTDLK-UHFFFAOYSA-N 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 150000004820 halides Chemical class 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 238000013038 hand mixing Methods 0.000 description 1
- KJZYNXUDTRRSPN-UHFFFAOYSA-N holmium atom Chemical compound [Ho] KJZYNXUDTRRSPN-UHFFFAOYSA-N 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000002386 leaching Methods 0.000 description 1
- OHSVLFRHMCKCQY-UHFFFAOYSA-N lutetium atom Chemical compound [Lu] OHSVLFRHMCKCQY-UHFFFAOYSA-N 0.000 description 1
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- 229910052751 metal Inorganic materials 0.000 description 1
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- 125000000896 monocarboxylic acid group Chemical group 0.000 description 1
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 150000002926 oxygen Chemical class 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- VQMWBBYLQSCNPO-UHFFFAOYSA-N promethium atom Chemical compound [Pm] VQMWBBYLQSCNPO-UHFFFAOYSA-N 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
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- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 1
- 229910052706 scandium Inorganic materials 0.000 description 1
- SIXSYDAISGFNSX-UHFFFAOYSA-N scandium atom Chemical compound [Sc] SIXSYDAISGFNSX-UHFFFAOYSA-N 0.000 description 1
- 238000000550 scanning electron microscopy energy dispersive X-ray spectroscopy Methods 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 159000000000 sodium salts Chemical class 0.000 description 1
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- NAWDYIZEMPQZHO-UHFFFAOYSA-N ytterbium Chemical compound [Yb] NAWDYIZEMPQZHO-UHFFFAOYSA-N 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 1
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Abstract
Description
本発明は、希土類元素混合硫酸複塩の選択的分離方法に係り、特に、希土類元素として軽希土類元素及び重希土類元素の両方を含む混合硫酸複塩から、重希土類元素の硫酸複塩を選択的に分離することの出来る有用な方法に関するものである。 The present invention relates to a method for selectively separating sulfuric acid double salts of rare earth elements, and in particular, selective separation of sulfuric acid double salts of heavy rare earth elements from mixed sulfuric acid double salts containing both light rare earth elements and heavy rare earth elements as rare earth elements. The present invention relates to a useful method that allows for the separation of
従来から、永久磁石やモーター、電極、ガラス研磨剤等の様々な分野において、各種の希土類元素が広く利用されており、そこでは、それらのスクラップ又は製造工程からの合金クズ等として、希土類元素を含有した排出物乃至は廃棄物が発生している。しかして、希土類元素は、希少資源であるところから、その有効利用を図るべく、そのような排出物乃至は廃棄物から、希土類元素を回収する手法や再利用するための手法に関して、各種の技術開発や検討が、精力的に行われてきている。特に、近年においては、希土類元素の需要拡大に加えて、産出国の政策や政情不安等によって、希土類元素の市場価格が大きな影響を受け、その変動が著しくなってきていることを受けて、従来からの希土類元素の回収技術に加え、更に実用上において有用な種々の回収方法の検討や、その開発が進められているのである。 Conventionally, various rare earth elements have been widely used in various fields such as permanent magnets, motors, electrodes, and glass abrasives. Containing emissions or waste are generated. However, since rare earth elements are rare resources, in order to utilize them effectively, various technologies have been developed regarding methods for recovering and reusing rare earth elements from such waste or waste. Development and study are being carried out vigorously. In particular, in recent years, in addition to the expanding demand for rare earth elements, the market prices of rare earth elements have been greatly affected by the policies and political instability of producing countries, and their fluctuations have become remarkable. In addition to technologies for recovering rare earth elements from the earth, research and development of various practically useful recovery methods are underway.
その中で、Ｎｄ－Ｂ－Ｆｅ合金磁石等の希土類元素含有材料から、簡便に且つ確実に、低温で鉄を除去して、希土類元素を回収し得る技術の一つとして、特開昭６３－２０６３１３号公報や特開２０１５－８９９７０号公報等においては、希土類元素のイオンを含む溶液に対して、硫酸ナトリウム等の硫酸塩及び硫酸を含む水溶液を接触せしめることにより、希土類元素の難溶性の硫酸複塩：Ｌｎ’Ｍ(ＳＯ4)2（但し、Ｌｎ’：希土類元素、Ｍ：アルカリ金属を示す）、換言すれば希土類硫酸塩とアルカリ硫酸塩とからなる難溶性の複塩を析出させる一方、鉄は溶解度の高い一般的な硫酸塩として、溶液中に残留するところから、濾過等の固液分離によって、希土類元素の硫酸複塩として、回収するようにした手法が知られているが、そこでは、希土類元素の硫酸複塩は、その析出が概ね完了するまでの時間が長く、条件によっては、充分な完了が実現され得ないことや、希土類元素の中で、軽希土類の硫酸複塩が難溶性であるのに対して、重希土類の硫酸複塩は溶解度が高いために、その充分な量の析出、回収が困難である等の問題を内在している。 Among these, Japanese Patent Laid-Open No. 1983-1999 is one of the technologies that can easily and reliably remove iron at low temperatures and recover rare earth elements from rare earth element-containing materials such as Nd-B-Fe alloy magnets. In 206313 and 2015-89970, etc., a solution containing ions of rare earth elements is brought into contact with an aqueous solution containing sulfuric acid and sulfuric acid, such as sodium sulfate, to obtain sulfuric acid that is sparingly soluble in rare earth elements. Double salt: Ln'M(SO 4 ) 2 (Ln': rare earth element, M: alkali metal), in other words, while precipitating a poorly soluble double salt consisting of a rare earth sulfate and an alkali sulfate. Since iron remains in solution as a common sulfate with high solubility, a method is known in which iron is recovered as a sulfate double salt of a rare earth element through solid-liquid separation such as filtration. However, the sulfuric acid double salt of a rare earth element takes a long time to complete its precipitation, and depending on the conditions, sufficient completion may not be achieved. is poorly soluble, whereas sulfuric acid double salts of heavy rare earths have high solubility, so they have inherent problems such as difficulty in precipitating and recovering a sufficient amount.
そこで、特開２０１３－１０４０９８号公報においては、希土類元素を含有する水溶液に、硫酸イオン以外の陰イオンを生じる水溶性塩類、例えば、塩化ニッケルの如き二価金属のハロゲン化物や、ハロゲンの酸素酸塩、硝酸塩等を共存させ、次いで、アルカリ金属硫酸塩を添加した後、溶液温度を５０℃以上として、反応させることにより、希土類元素の硫酸複塩を析出させて、沈殿せしめる回収方法が明らかにされており、これによって、効率的に且つ高い回収率において、希土類元素を回収することが出来るとされている。更に、特開２０１５－１１０８１１号公報には、反応槽に収容した希土類元素を含有する溶液に、種晶を共存させた状態で、アルカリ金属硫酸塩を添加して、６０℃まで昇温し、そして３時間以上保持することにより、希土類元素の硫酸複塩生成反応を生じさせ、希土類元素の硫酸複塩沈殿物を形成させて、回収する回収方法において、反応槽内に残留させた種晶に、先ず、アルカリ金属硫酸塩を含む溶液を添加してスラリーとし、その後、希土類元素を含む硫酸水溶液を収容するようにすることによって、希土類硫酸複塩の形態が変化せず、共沈効果が低下するのを抑制し、高い回収率で安定して希土類を回収することが出来るとの指摘が為されている。 Therefore, in JP-A No. 2013-104098, water-soluble salts that generate anions other than sulfate ions, such as halides of divalent metals such as nickel chloride, and oxygen acids of halogens, are added to an aqueous solution containing rare earth elements. A recovery method has been revealed in which sulfuric acid double salts of rare earth elements are precipitated by allowing salts, nitrates, etc. to coexist, then adding an alkali metal sulfate, and then reacting at a solution temperature of 50°C or higher. It is said that this makes it possible to recover rare earth elements efficiently and at a high recovery rate. Furthermore, in JP 2015-110811, an alkali metal sulfate is added to a solution containing a rare earth element contained in a reaction tank in the presence of seed crystals, and the temperature is raised to 60 ° C. By holding it for 3 hours or more, a sulfuric acid double salt formation reaction of rare earth elements occurs, and a rare earth sulfuric acid double salt precipitate is formed and recovered. First, a solution containing an alkali metal sulfate is added to form a slurry, and then a sulfuric acid aqueous solution containing a rare earth element is contained, so that the form of the rare earth sulfate double salt does not change and the coprecipitation effect is reduced. It has been pointed out that rare earths can be recovered stably at a high recovery rate.
しかしながら、それら硫酸複塩沈殿法によって希土類元素を回収する従来の方法にあっては、希土類元素として、プラセオジムやネオジム等の軽希土類元素と共に、テルビウムやジスプロシウム等の重希土類元素を含む溶液から硫酸複塩を析出させると、それら軽希土類元素及び重希土類元素を含む混合硫酸複塩、換言すれば軽希土類硫酸塩と重希土類硫酸塩とアルカリ硫酸塩とからなる混合硫酸複塩が、形成されることとなるのであり、そこでは、軽希土類元素の硫酸複塩や重希土類元素の硫酸複塩を選択的に生成せしめたり、或いは選択的に分離せしめたりし得るものではなかったのである。 However, in the conventional method of recovering rare earth elements by the sulfuric acid double salt precipitation method, the sulfuric acid complex is extracted from a solution containing heavy rare earth elements such as terbium and dysprosium as well as light rare earth elements such as praseodymium and neodymium. When the salt is precipitated, a mixed sulfuric acid double salt containing these light rare earth elements and heavy rare earth elements, in other words, a mixed sulfuric acid double salt consisting of a light rare earth sulfate, a heavy rare earth sulfate, and an alkali sulfate, is formed. Therefore, it has not been possible to selectively generate or selectively separate the sulfuric acid double salts of light rare earth elements and the sulfuric acid double salts of heavy rare earth elements.
また、特開２０１２－２２９４８３号公報においては、効率的に且つ高い回収率で、重希土類元素を回収することが出来る重希土類元素の回収方法として、重希土類元素と軽希土類元素とを含有する溶液に、アルカリ金属硫酸塩を所定の硫酸イオン濃度となるように添加して、撹拌することにより、重希土類元素を軽希土類元素の硫酸複塩に共沈させて、回収するようにした方法が明らかにされ、更に特開２０１４－２１８７００号公報においては、そのような重希土類元素の回収方法において、希土類元素含有溶液中に、種晶として、希土類元素の硫酸複塩沈殿を加え、軽希土類元素の全体としての濃度が高くなるように管理して、安定的に重希土類元素を回収し得るようにした回収方法が、提案されているのであるが、そこで得られる硫酸複塩は、軽希土類硫酸塩と共に、重希土類硫酸塩が、アルカリ硫酸塩との複塩とされてなる形態の混合硫酸複塩となるものであって、軽希土類元素の硫酸複塩と重希土類元素の硫酸複塩とを、選択的に分離せしめ得るものではなかったのである。 Furthermore, in JP-A No. 2012-229483, a solution containing heavy rare earth elements and light rare earth elements is described as a method for recovering heavy rare earth elements that can efficiently and with a high recovery rate. A method has been revealed in which heavy rare earth elements are co-precipitated with sulfuric acid double salts of light rare earth elements by adding alkali metal sulfate to a predetermined sulfate ion concentration and stirring, thereby recovering the heavy rare earth elements. Furthermore, in JP-A No. 2014-218700, in such a heavy rare earth element recovery method, a sulfuric acid double salt precipitate of a rare earth element is added as a seed crystal to a rare earth element-containing solution, and a light rare earth element is recovered. A recovery method has been proposed in which heavy rare earth elements can be stably recovered by managing the overall concentration to be high, but the sulfate double salt obtained by this method is different from light rare earth sulfate. In addition, the heavy rare earth sulfate becomes a mixed sulfuric acid double salt in the form of a double salt with an alkali sulfate, and the sulfuric acid double salt of a light rare earth element and the sulfuric acid double salt of a heavy rare earth element, It was not possible to separate them selectively.
ここにおいて、本発明は、上述の如き事情を背景にして完成されたものであって、その解決課題とするところは、重希土類元素と軽希土類元素との混合硫酸複塩から、重希土類元素の硫酸複塩を選択的に分離することの出来る方法を提供することにあり、また他の課題とするところは、重希土類元素及び軽希土類元素を含む混合硫酸複塩中の重希土類元素の硫酸複塩を効果的に溶出せしめ得る方法を提供することにある。 The present invention was completed against the background of the above-mentioned circumstances, and the problem to be solved is to convert the mixed sulfuric acid double salt of heavy rare earth elements and light rare earth elements into The purpose is to provide a method that can selectively separate sulfuric acid double salts, and another problem is to separate sulfuric acid double salts of heavy rare earth elements in mixed sulfuric acid double salts containing heavy rare earth elements and light rare earth elements. The object of the present invention is to provide a method that can effectively elute salts.
そして、本発明にあっては、かくの如き課題の解決のために、重希土類元素と軽希土類元素との混合硫酸複塩から重希土類元素の硫酸複塩を選択的に分離する方法にして、該混合硫酸複塩を、３モル濃度以上の硫酸からなる液状媒体に接触させることにより、該混合硫酸複塩中の重希土類元素の硫酸複塩を選択的に溶出せしめることを特徴とする希土類元素混合硫酸複塩の選択的分離方法を、その要旨とするものである。 In order to solve such problems, the present invention provides a method for selectively separating a sulfuric acid double salt of a heavy rare earth element from a mixed sulfuric acid double salt of a heavy rare earth element and a light rare earth element, A rare earth element characterized in that the sulfuric acid double salt of the heavy rare earth element in the mixed sulfuric double salt is selectively eluted by contacting the mixed sulfuric acid double salt with a liquid medium consisting of sulfuric acid with a molar concentration of 3 or more. The gist of this paper is a method for selectively separating mixed sulfuric acid double salts.
なお、このような本発明に従う希土類元素混合硫酸複塩の選択的分離方法においては、有利には、前記液状媒体として、４～６モル濃度の硫酸が用いられることとなる。 In the method for selectively separating a rare earth element mixed sulfuric acid double salt according to the present invention, sulfuric acid having a concentration of 4 to 6 molar is advantageously used as the liquid medium.
また、かかる本発明に従う希土類元素混合硫酸複塩の選択的分離方法の望ましい態様の一つによれば、前記混合硫酸複塩が、ＬｎＭ(ＳＯ4)2（但し、Ｌｎは、少なくとも１種の重希土類元素及び少なくとも１種の軽希土類元素を示し、Ｍは、アルカリ金属を示す）にて表される硫酸複塩であることを特徴としている。 Further, according to one of the desirable embodiments of the method for selectively separating a rare earth element mixed sulfate double salt according to the present invention, the mixed sulfuric acid double salt is LnM(SO 4 ) 2 (provided that Ln is at least one of It is characterized by being a sulfuric acid double salt represented by a heavy rare earth element and at least one light rare earth element, and M represents an alkali metal.
さらに、本発明に従う希土類元素混合硫酸複塩の選択的分離方法の別の望ましい態様の一つによれば、前記混合硫酸複塩が、希土類元素として、軽希土類元素と共に、重希土類元素を含む水性溶液に対して、酢酸を配合して、均一に混合せしめた後、その得られた混合液に、硫酸のアルカリ金属塩を固体形態において添加して、溶解させることにより、析出せしめられてなるものであることを特徴とする。 Furthermore, according to another desirable embodiment of the method for selectively separating a rare earth element mixed sulfate double salt according to the present invention, the mixed sulfate double salt is an aqueous sulfuric acid containing a heavy rare earth element as well as a light rare earth element as the rare earth element. A substance that is precipitated by adding acetic acid to a solution and mixing it uniformly, then adding an alkali metal salt of sulfuric acid in solid form to the resulting mixture and dissolving it. It is characterized by
なお、このような本発明に従う希土類元素混合硫酸複塩の選択的分離方法の好ましい態様の一つによれば、前記硫酸のアルカリ金属塩が、固形の硫酸ナトリウムであることを特徴としている。 According to a preferred embodiment of the method for selectively separating a rare earth element mixed sulfuric acid double salt according to the present invention, the alkali metal salt of sulfuric acid is solid sodium sulfate.
更にまた、かかる本発明に従う希土類元素混合硫酸複塩の選択的分離方法の別の好ましい態様の一つによれば、前記混合硫酸複塩が、希土類系磁石合金材料から、硫酸複塩沈殿法によって得られたものであることを特徴とする。 Furthermore, according to another preferred embodiment of the method for selectively separating a rare earth element mixed sulfuric acid double salt according to the present invention, the mixed sulfuric acid double salt is separated from a rare earth magnet alloy material by a sulfuric acid double salt precipitation method. It is characterized by being obtained.
加えて、本発明に従う希土類元素混合硫酸複塩の選択的分離方法の他の望ましい態様の一つによれば、前記選択的な溶出操作によって得られた溶出液に対して、蓚酸を添加することにより、軽希土類元素に対する重希土類元素の比率が高められた硫酸と蓚酸の複塩を析出させて、その析出物を分離することを特徴としている。 In addition, according to another desirable embodiment of the method for selectively separating rare earth element mixed sulfuric acid double salts according to the present invention, oxalic acid is added to the eluate obtained by the selective elution operation. The method is characterized by precipitating a double salt of sulfuric acid and oxalic acid in which the ratio of heavy rare earth elements to light rare earth elements is increased, and separating the precipitate.
そして、このような本発明に従う希土類元素混合硫酸複塩の選択的分離方法によれば、重希土類元素及び軽希土類元素を含む混合硫酸複塩から、重希土類元素の硫酸複塩を、選択的に有利に分離することが可能となったのであり、一方、重希土類元素の含有率が大幅に低減されて、軽希土類元素の含有量が効果的に向上せしめられた硫酸複塩（固体）が、有利に採取され得ることとなるのである。 According to the method for selectively separating rare earth element mixed sulfuric acid double salts according to the present invention, heavy rare earth element sulfuric acid double salts are selectively separated from mixed sulfuric acid double salts containing heavy rare earth elements and light rare earth elements. On the other hand, the sulfuric acid double salt (solid) has a significantly reduced content of heavy rare earth elements and an effectively increased content of light rare earth elements. This means that they can be harvested advantageously.
先ず、本発明に従う希土類元素混合硫酸複塩の選択的分離方法において、その対象とされる、重希土類元素と軽希土類元素との混合硫酸複塩は、希土類元素として、軽希土類元素と共に、重希土類元素を含む溶液から、従来と同様にして、硫酸複塩沈殿法によって析出せしめて得られるものであって、軽希土類硫酸塩と重希土類硫酸塩とアルカリ硫酸塩とからなる難溶性の複塩であり、一般に、ＬｎＭ(ＳＯ4)2（但し、Ｌｎは、少なくとも１種の重希土類元素及び少なくとも１種の軽希土類元素を示し、Ｍは、アルカリ金属を示す）にて表される硫酸複塩である。ここで、希土類元素のうちの、軽希土類元素としては、スカンジウム、ランタン、セリウム、プラセオジム、ネオジム、プロメチウム、サマリウム等があり、また重希土類元素としては、イットリウム、ユーロピウム、ガドリニウム、テルビウム、ジスプロシウム、ホルミウム、エルビウム、ツリウム、イッテルビウム、ルテチウム等があり、それら軽希土類元素及び重希土類元素の中から、それぞれ、１種若しくは２種以上を含む混合硫酸複塩が用いられることとなる。 First, in the selective separation method of rare earth element mixed sulfuric acid double salt according to the present invention, the mixed sulfuric acid double salt of a heavy rare earth element and a light rare earth element, which is the subject of the method, is selected as a rare earth element, as well as a heavy rare earth element. It is obtained by precipitating a solution containing elements by the sulfuric acid double salt precipitation method in the same manner as before, and is a sparingly soluble double salt consisting of light rare earth sulfate, heavy rare earth sulfate, and alkali sulfate. Generally, a sulfuric acid double salt represented by LnM(SO 4 ) 2 (Ln represents at least one heavy rare earth element and at least one light rare earth element, and M represents an alkali metal) It is. Among the rare earth elements, light rare earth elements include scandium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, etc., and heavy rare earth elements include yttrium, europium, gadolinium, terbium, dysprosium, and holmium. , erbium, thulium, ytterbium, lutetium, etc., and a mixed sulfuric acid double salt containing one or more of these light rare earth elements and heavy rare earth elements is used.
そして、本発明にあっては、希土類元素として、軽希土類元素と共に、重希土類元素を含む水性溶液に対して、酢酸を配合して、均一に混合せしめた後、その得られた混合液に対して、硫酸のアルカリ金属塩、例えばナトリウム塩やカリウム塩等を、固体形態において添加して、溶解させることにより、析出せしめて、得られる混合硫酸複塩が、有利に用いられることとなる。このように、硫酸のアルカリ金属塩を、固体で、例えば粉末や粒体の形態において用いて、酢酸の配合された混合液に添加することにより、混合液中に存在する希土類元素（軽希土類＋重希土類）の硫酸複塩化反応が効果的に促進せしめられ得ることとなり、これによって、目的とする軽希土類元素及び重希土類元素の硫酸複塩が、極めて迅速に且つ高い析出率において、有利に形成せしめられ得るのである。 In the present invention, acetic acid is blended into an aqueous solution containing a heavy rare earth element as well as a light rare earth element as a rare earth element, and after uniformly mixing, the resulting mixed solution is mixed. The mixed sulfuric acid double salt obtained by adding an alkali metal salt of sulfuric acid, such as a sodium salt or a potassium salt, in solid form and dissolving it to precipitate the mixture is advantageously used. In this way, by using an alkali metal salt of sulfuric acid in solid form, for example in powder or granule form, and adding it to a mixture containing acetic acid, rare earth elements (light rare earths + The sulfuric acid double chloride reaction of heavy rare earth elements) can be effectively promoted, and the target sulfuric acid double salts of light rare earth elements and heavy rare earth elements can be advantageously formed extremely quickly and at a high precipitation rate. It can be forced.
なお、そこにおいて、軽希土類元素及び重希土類元素を含む水性溶液に配合される酢酸は、本発明において対象とする混合硫酸複塩の形成反応の促進に寄与する成分であって、その配合によって、硫酸複塩の析出が迅速に行われ得るものである。また、そのような酢酸の配合量としては、目的に応じて適宜に選定されることとなるが、一般に、各希土類元素を含有する水性溶液と酢酸との混合液中において、１重量％以上、好ましくは５重量％以上、更に好ましくは１０重量％以上の含有量となる割合において、適宜に選定されることとなる。 In addition, the acetic acid blended into the aqueous solution containing light rare earth elements and heavy rare earth elements is a component that contributes to the promotion of the formation reaction of the mixed sulfuric acid double salt targeted in the present invention, and by its blending, The sulfuric acid double salt can be rapidly precipitated. In addition, the amount of acetic acid to be blended will be appropriately selected depending on the purpose, but generally, in a mixed solution of aqueous solution containing each rare earth element and acetic acid, 1% by weight or more, The proportion is appropriately selected such that the content is preferably 5% by weight or more, more preferably 10% by weight or more.
そして、かくの如くして硫酸複塩沈殿法によって析出せしめられた軽希土類元素及び重希土類元素の混合硫酸複塩（固体）は、Ｌｎ2(ＳＯ4)3・Ｍ2ＳＯ4・ｘＨ2Ｏとして示される水和物の形態において、従来と同様にして、濾過等の分離操作にて溶液から取り出されて、本発明に従う選択的分離方法が、適用されるのである。 The mixed sulfuric acid double salt (solid) of light rare earth elements and heavy rare earth elements thus precipitated by the sulfuric acid double salt precipitation method is Ln 2 (SO 4 ) 3 .M 2 SO 4 .xH 2 O In the form of a hydrate shown as , it is removed from the solution by a separation operation such as filtration in the same manner as in the past, and the selective separation method according to the present invention is applied.
なお、上述の如くして得られる本発明が適用される混合硫酸複塩を与える、軽希土類元素と共に重希土類元素を含む溶液は、従来と同様な手法によって得られるものであって、例えば、永久磁石やモーター、電極、ガラス研磨剤等の様々な使用分野において回収される各種の希土類元素含有材料を、硫酸以外の鉱酸、例えば塩酸等で滲出乃至は溶解して得られた滲出液乃至は溶解液が、用いられ得るものである。また、そこにおいて、希土類元素含有材料としては、希土類系磁石合金材料が、好適にその対象とされることとなる。更に、そのような希土類系磁石合金材料の中でも、希土類元素－鉄系、特に、ネオジム－鉄－ボロン（Ｎｄ－Ｆｅ－Ｂ）系の磁石合金材料が、その製造工程から排出された材料や製品から回収された材料として、そのままの状態で、或いは必要に応じて粗砕や粉砕等によって適当な大きさに細分化して、有利に用いられることとなる。 Note that the solution containing heavy rare earth elements as well as light rare earth elements, which provides the mixed sulfuric acid double salt to which the present invention is applied, obtained as described above, can be obtained by a conventional method, and, for example, can be permanently Exudates or exudates obtained by leaching or dissolving various rare earth element-containing materials collected in various fields of use such as magnets, motors, electrodes, and glass polishing agents with mineral acids other than sulfuric acid, such as hydrochloric acid. A lysing solution is one that can be used. Furthermore, in this case, the rare earth element-containing material is preferably a rare earth magnet alloy material. Furthermore, among such rare earth magnet alloy materials, rare earth element-iron based magnet alloy materials, especially neodymium-iron-boron (Nd-Fe-B) based magnet alloy materials, are used as materials and products discharged from the manufacturing process. It can be advantageously used as a material recovered from the plant as it is, or after being divided into appropriate sizes by crushing or pulverizing as necessary.
そして、本発明にあっては、上述の如くして固体形態において取り出された、重希土類元素と軽希土類元素とを含む混合硫酸複塩から、重希土類元素の硫酸複塩を選択的に分離するべく、かかる混合硫酸複塩を、３モル濃度（３Ｍ）以上の硫酸からなる液状媒体に接触させて、そのような混合硫酸複塩中の重希土類元素の硫酸複塩を、かかる液状媒体中に選択的に溶出せしめて、重希土類元素を取り出すようにする一方、軽希土類元素の硫酸複塩は、そのまま、固体状態において残留するようにしたのである。 In the present invention, the sulfuric acid double salt of a heavy rare earth element is selectively separated from the mixed sulfuric acid double salt containing a heavy rare earth element and a light rare earth element extracted in solid form as described above. In order to achieve this, the mixed sulfuric acid double salt is brought into contact with a liquid medium consisting of sulfuric acid with a concentration of 3 molar or more (3M), and the sulfuric acid double salt of the heavy rare earth element in the mixed sulfuric acid double salt is dissolved in the liquid medium. The heavy rare earth elements were extracted by selective elution, while the sulfuric acid double salts of the light rare earth elements remained as they were in a solid state.
ここで、混合硫酸複塩からの重希土類元素の硫酸複塩の選択的な溶出には、混合硫酸複塩が接触せしめられる液状媒体中の硫酸濃度（Ｍ）が重要であり、その濃度を３モル濃度（３Ｍ）以上とすることにより、重希土類元素の硫酸複塩の溶出が効果的に行われ得ることとなるのであり、特に、硫酸濃度の上昇につれて、軽希土類元素の硫酸複塩の溶解性は低下する一方、重希土類元素の硫酸複塩の高い溶解性を維持し得ることとなるが、有利には、４～６モル濃度（Ｍ）の硫酸を含む水性の液状媒体を用いて、混合硫酸複塩の接触処理を実施することにより、軽希土類元素の硫酸複塩と重希土類元素の硫酸複塩との間の溶解性差を大きくすることが出来る利点を享受することが可能となる。 Here, the sulfuric acid concentration (M) in the liquid medium with which the mixed sulfuric acid double salts are brought into contact is important for the selective elution of the sulfuric acid double salts of heavy rare earth elements from the mixed sulfuric acid double salts. By setting the molar concentration (3M) or more, the sulfuric acid double salt of heavy rare earth elements can be effectively eluted, and in particular, as the sulfuric acid concentration increases, the dissolution of the sulfuric acid double salt of light rare earth elements increases. Advantageously, an aqueous liquid medium containing 4 to 6 molar concentration (M) of sulfuric acid can be used to maintain high solubility of the sulfuric acid double salt of a heavy rare earth element, although the By carrying out the contact treatment of mixed sulfuric acid double salts, it is possible to enjoy the advantage of increasing the solubility difference between the sulfuric acid double salts of light rare earth elements and the sulfuric acid double salts of heavy rare earth elements.
なお、混合硫酸複塩と液状媒体との接触処理は、公知の各種の手法にて実施することが可能であるが、一般に、固体の混合硫酸複塩を所定濃度の硫酸を含む液状媒体中に投入して、混合撹拌する手法が採用され、その際、接触処理時間としては、一般に、０．２～１２時間程度、好ましくは０．５～６時間程度、より好ましくは４～６時間程度が採用されることとなる。 The contact treatment between the mixed sulfuric acid double salt and the liquid medium can be carried out using various known methods, but in general, the solid mixed sulfuric acid double salt is placed in a liquid medium containing sulfuric acid at a predetermined concentration. A method of adding and mixing and stirring is adopted, and in this case, the contact treatment time is generally about 0.2 to 12 hours, preferably about 0.5 to 6 hours, and more preferably about 4 to 6 hours. It will be adopted.
そして、このような接触処理により、所定濃度の硫酸を含む液状媒体中には、重希土類元素の硫酸複塩が選択的に溶出せしめられて、重希土類元素のリッチな液状媒体からなる溶出液が形成される一方、そのような溶出液から、溶解されずに残留する固形の成分として、軽希土類元素がリッチな硫酸複塩からなる残留物が、公知の濾過等の分離操作にて取り出されることによって、それぞれ液体及び固体として回収されることとなる。 Through such contact treatment, the sulfuric acid double salt of the heavy rare earth element is selectively eluted into the liquid medium containing sulfuric acid at a predetermined concentration, and an eluent consisting of the liquid medium rich in heavy rare earth elements is formed. On the other hand, a residue consisting of a sulfuric acid double salt rich in light rare earth elements can be removed from such eluate as a solid component that remains undissolved through known separation operations such as filtration. They will be recovered as liquids and solids, respectively.
また、かくの如き選択的な溶出操作によって得られた溶出液（溶出処理後の液状媒体）には、その溶出成分を分離すべく、本発明においては、有利には、蓚酸が添加せしめられ、これによって、軽希土類元素に対する重希土類元素の比率が高められた硫酸と蓚酸の複塩が析出せしめられた後、その析出物を分離する操作が実施される。これにより、重希土類元素がリッチな複塩（固体）が、有利に取り出され得るのである。 Further, in the present invention, oxalic acid is advantageously added to the eluate (liquid medium after elution treatment) obtained by such selective elution operation in order to separate the eluate components, As a result, a double salt of sulfuric acid and oxalic acid with an increased ratio of heavy rare earth elements to light rare earth elements is precipitated, and then an operation is performed to separate the precipitate. Thereby, a double salt (solid) rich in heavy rare earth elements can be advantageously extracted.
以下に、本発明の代表的な実施例を、比較例と共に示し、本発明を更に具体的に明らかにすることとするが、本発明が、それら実施例や比較例の記載によって、何等の制約をも受けるものでないことは、言うまでもないところである。また、本発明には、以下の実施例の他にも、本発明の主旨を逸脱しない限りにおいて、当業者の知識に基づいて種々なる変更、修正、改良等を加え得るものであることが、理解されるべきである。 Below, typical examples of the present invention will be shown together with comparative examples to clarify the present invention more specifically. Needless to say, this is not something that can be accepted. Furthermore, in addition to the following examples, various changes, modifications, improvements, etc. can be made to the present invention based on the knowledge of those skilled in the art, as long as they do not depart from the spirit of the present invention. should be understood.
［実施例１］
重希土類元素として、テルビウム（Ｔｂ）及びジスプロシウム（Ｄｙ）を含み、且つ軽希土類元素として、プラセオジム（Ｐｒ）及びネオジム（Ｎｄ）を含む溶液から、硫酸複塩沈殿法によって析出せしめられた後、分離することによって得られた、モル比で、Ｐｒ：Ｎｄ：Ｔｂ：Ｄｙ＝３．１：２．３：１．０：０．４の組成を有する固形の混合硫酸複塩：ＬｎＮａ(ＳＯ4)2（Ｌｎ＝Ｐｒ、Ｎｄ、Ｔｂ、Ｄｙ）を、各種濃度の塩酸、硝酸又は硫酸に添加して、液温：２５℃において、０．５～１２時間の撹拌（３０００ｒｐｍ）を行い、その溶解性を調べた。
[Example 1]
After being precipitated by a sulfuric acid double salt precipitation method from a solution containing terbium (Tb) and dysprosium (Dy) as heavy rare earth elements and praseodymium (Pr) and neodymium (Nd) as light rare earth elements, it is separated. A solid mixed sulfuric acid double salt: LnNa(SO 4 ) having a molar ratio of Pr:Nd:Tb:Dy=3.1:2.3:1.0:0.4 was obtained by 2 (Ln=Pr, Nd, Tb, Dy) was added to various concentrations of hydrochloric acid, nitric acid, or sulfuric acid, and stirred (3000 rpm) for 0.5 to 12 hours at a liquid temperature of 25°C to dissolve it. I looked into gender.
その結果、３種の鉱酸のうち、塩酸及び硝酸については、それぞれ、０．１Ｍ、０．５Ｍ、１．０Ｍ、３．０Ｍ、４．０Ｍ、５．０Ｍ、及び６．０Ｍの何れの濃度においても、換言すれば、酸濃度に依存することなく、添加された混合硫酸複塩は、完全に溶解されていることを認めた。 As a result, among the three types of mineral acids, hydrochloric acid and nitric acid were found to be 0.1M, 0.5M, 1.0M, 3.0M, 4.0M, 5.0M, and 6.0M, respectively. In other words, it was confirmed that the added mixed sulfuric acid double salt was completely dissolved regardless of the acid concentration.
これに対して、０．１Ｍから６．０Ｍに至る、各種濃度の硫酸を用いて、１２時間の撹拌を行った場合において、硫酸濃度の上昇に伴い、希土類元素の混合硫酸複塩の溶解性が低下することが、溶け残りの存在と共に、硫酸中に溶け出した各元素の溶解性分析（ＩＣＰ－ＡＥＳ）により、Ｎａ及び希土類元素の濃度が低下する傾向があることから、明らかとなった。更に、硫酸濃度が４Ｍ以上において、１２時間後の外観検査により、複塩の溶け残りが顕著となることが認められた。 On the other hand, when stirring was performed for 12 hours using various concentrations of sulfuric acid ranging from 0.1M to 6.0M, the solubility of mixed sulfuric acid double salts of rare earth elements decreased as the sulfuric acid concentration increased. In addition to the presence of undissolved elements, solubility analysis (ICP-AES) of each element dissolved in sulfuric acid revealed that the concentrations of Na and rare earth elements tended to decrease. . Furthermore, when the sulfuric acid concentration was 4M or more, visual inspection after 12 hours showed that the double salt remained undissolved.
また、かかる硫酸に対する溶解性テストにおいて、溶け残った混合硫酸複塩の組成解析を、ＳＥＭ／ＥＤＸ分析により実施して、未溶解混合硫酸複塩における重希土類元素（Ｔｂ、Ｄｙ）の含有率が低いことを確認した。そして、上記の溶解性分析（ＩＣＰ－ＡＥＳ）の結果を、下記表１に示すと共に、硫酸濃度に対する各希土類元素の複塩溶解率（Ｔｂ基準）の関係を、図１に示した。なお、各希土類元素の複塩の溶解率は、０．１Ｍの硫酸に完全溶解した複塩組成中のＴｂ分析値を基準として、求められたものである。 In addition, in the solubility test for sulfuric acid, the composition of the undissolved mixed sulfuric acid double salt was analyzed by SEM/EDX analysis, and the content of heavy rare earth elements (Tb, Dy) in the undissolved mixed sulfuric acid double salt was determined. I confirmed that it was low. The results of the above solubility analysis (ICP-AES) are shown in Table 1 below, and the relationship between the double salt dissolution rate (Tb standard) of each rare earth element with respect to the sulfuric acid concentration is shown in FIG. The dissolution rate of the double salt of each rare earth element was determined based on the Tb analysis value in the double salt composition completely dissolved in 0.1M sulfuric acid.
［実施例２］
Ｎｄ－Ｂ－Ｆｅ系合金からなる廃磁石材料（Ｌｎ：Ｐｒ、Ｎｄ、Ｔｂ、Ｄｙ含有）を塩酸に溶解して、ｐＨを約３に調整することにより、得られた希土類元素含有溶液を用い、この溶液に、酢酸を１０％濃度となるように添加して、１５分間撹拌した後、硫酸ナトリウム粉末を反応当量に相当する量において添加し、手振り混合を行って、かかる硫酸ナトリウム粉末を溶解させることによって、２５℃の温度で、希土類元素の混合硫酸複塩を析出せしめ、更に濾過により、その析出した混合硫酸複塩を回収した。
[Example 2]
By dissolving waste magnet material (Ln: contains Pr, Nd, Tb, Dy) made of Nd-B-Fe alloy in hydrochloric acid and adjusting the pH to about 3, the obtained rare earth element-containing solution is used. To this solution, acetic acid was added to a concentration of 10%, and after stirring for 15 minutes, sodium sulfate powder was added in an amount corresponding to the reaction equivalent, and the sodium sulfate powder was dissolved by hand mixing. By this, a mixed sulfuric acid double salt of a rare earth element was precipitated at a temperature of 25° C., and the precipitated mixed sulfuric acid double salt was recovered by filtration.
次いで、かかる得られた混合硫酸複塩を、３．０Ｍ～９．０Ｍの各種濃度の硫酸に、それぞれ投入して、２５℃の温度で、１２時間撹拌（３５０ｒｐｍ）することにより、溶出処理を実施した。 Next, the obtained mixed sulfuric acid double salts were added to sulfuric acid of various concentrations from 3.0 M to 9.0 M, and the elution treatment was carried out by stirring (350 rpm) at a temperature of 25° C. for 12 hours. carried out.
そして、かかる溶出処理にて得られた各種の溶出液（各種濃度の硫酸）において、その溶出された硫酸複塩の組成を、それぞれＩＣＰ－ＡＥＳ分析して、その結果を、下記表２に示した。また、それぞれの硫酸濃度における複塩の溶解率について、実施例１と同様にして求め、その結果を、図２に示した。なお、各希土類元素の複塩の溶解率は、１．０Ｍの硝酸に完全溶解した複塩組成中のＰｒ分析値を基準として、求められたものである。 The compositions of the eluted sulfuric acid double salts in the various eluates (sulfuric acid of various concentrations) obtained through such elution treatment were analyzed by ICP-AES, and the results are shown in Table 2 below. Ta. Further, the dissolution rate of the double salt at each sulfuric acid concentration was determined in the same manner as in Example 1, and the results are shown in FIG. Note that the dissolution rate of the double salt of each rare earth element was determined based on the Pr analysis value in the double salt composition completely dissolved in 1.0 M nitric acid.
かかる表２の結果や図２より明らかな如く、軽希土類元素（Ｐｒ、Ｎｄ）や重希土類元素（Ｔｂ、Ｄｙ）を含む混合硫酸複塩に対して、３Ｍ以上の濃度の硫酸を用いて溶出処理することにより、重希土類元素（Ｔｂ、Ｄｙ）の複塩が選択的に溶出され得ることとなることが認められる。また、そこでは、軽希土類元素（Ｐｒ、Ｎｄ）の複塩は、４Ｍ以上の濃度の硫酸に対して、その溶解性が低下する一方、重希土類元素（Ｔｂ、Ｄｙ）の複塩においては、６Ｍ以上の濃度の硫酸に対して、その溶解性が低下するようになるところから、４～６Ｍの濃度の硫酸による溶出処理が、軽希土類元素複塩／重希土類元素複塩の大きな溶解性差を得ることが出来るために、有利であることが、認められる。 As is clear from the results in Table 2 and Figure 2, it is possible to elute mixed sulfuric acid double salts containing light rare earth elements (Pr, Nd) and heavy rare earth elements (Tb, Dy) using sulfuric acid with a concentration of 3M or more. It is recognized that the treatment allows double salts of heavy rare earth elements (Tb, Dy) to be selectively eluted. In addition, double salts of light rare earth elements (Pr, Nd) have reduced solubility in sulfuric acid with a concentration of 4M or more, while double salts of heavy rare earth elements (Tb, Dy) have Since the solubility of sulfuric acid decreases when the concentration is 6M or higher, elution treatment with sulfuric acid at a concentration of 4 to 6M can eliminate the large solubility difference between light rare earth element double salts and heavy rare earth element double salts. It is recognized that it is advantageous because it can be obtained.
また、上記の溶出処理にて得られた溶出液５０ｍｌについて、溶出希土類元素（Ｔｂ＋Ｄｙ＝８５．８ｍＭ）に対する化学量論比の割合となる蓚酸［（ＣＯＯＨ）2・２Ｈ2Ｏ］０．８１１ｇを配合して、保持したところ、重希土類元素（Ｔｂ、Ｄｙ）リッチな硫酸と蓚酸の複塩が析出した。その後、通常の濾過を実施することにより、その析出した複塩を回収することが出来た。 Furthermore, for 50 ml of the eluate obtained in the above elution process, 0.811 g of oxalic acid [(COOH) 2.2H 2 O], which has a stoichiometric ratio to the eluted rare earth element (Tb + Dy = 85.8 mM), was added. When blended and held, a double salt of sulfuric acid and oxalic acid rich in heavy rare earth elements (Tb, Dy) was precipitated. Thereafter, the precipitated double salt could be recovered by performing normal filtration.
［実施例３］
実施例２において得られた軽希土類元素（Ｐｒ、Ｎｄ）と共に、重希土類元素（Ｔｂ、Ｄｙ）を含む混合硫酸複塩を用いて、それを、４Ｍ濃度の硫酸に添加して、２５℃の温度で０．５～１２時間の間、撹拌（３５０ｒｐｍ）することにより、溶出処理を実施した。そして、その得られた溶出液を、濾過操作にて分離した後、実施例２と同様にして、各溶出時間に対する各希土類元素の複塩溶解率を求め、その結果を、図３に示した。
[Example 3]
Using a mixed sulfuric acid double salt containing heavy rare earth elements (Tb, Dy) together with the light rare earth elements (Pr, Nd) obtained in Example 2, it was added to 4M sulfuric acid and heated at 25°C. The elution process was carried out by stirring (350 rpm) for a period of 0.5 to 12 hours at temperature. After separating the obtained eluate by a filtration operation, the double salt dissolution rate of each rare earth element for each elution time was determined in the same manner as in Example 2, and the results are shown in Figure 3. .
そして、図３の結果より明らかなように、軽希土類元素と重希土類元素の混合硫酸複塩から、重希土類元素の複塩を選択的に溶出させる際には、０．５～６時間程度、好ましくは４～６時間程度の撹拌が望ましいことを認めることが出来る。 As is clear from the results in Figure 3, when selectively eluting the double salt of a heavy rare earth element from the mixed sulfuric acid double salt of a light rare earth element and a heavy rare earth element, it takes about 0.5 to 6 hours. It can be recognized that stirring for about 4 to 6 hours is desirable.
Claims (7)
該混合硫酸複塩を、３モル濃度以上の硫酸からなる液状媒体に接触させることにより、該混合硫酸複塩中の重希土類元素の硫酸複塩を選択的に溶出せしめることを特徴とする希土類元素混合硫酸複塩の選択的分離方法。 A method for selectively separating sulfuric acid double salts of heavy rare earth elements from mixed sulfuric acid double salts of heavy rare earth elements and light rare earth elements,
A rare earth element characterized in that the sulfuric acid double salt of the heavy rare earth element in the mixed sulfuric double salt is selectively eluted by contacting the mixed sulfuric acid double salt with a liquid medium consisting of sulfuric acid with a molar concentration of 3 or more. Selective separation method for mixed sulfuric acid double salts.
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