Shin-etsu Chemical Co., Ltd.

Japan Atomic Energy Agency

Nissin Chemical Industry Co., Ltd.

Brother Kogyo Kabushiki-kaisha

Hiroto Sugahara

Kazuaki Sakaki

Hirochika Naganawa

Kojiro Shimojo

Takehisa Minowa

Tetsuya Kume

Masaki Ohashi

Shingo Hattori

Masatoshi Ishii

Naofumi Shinya

Tetsuya Ohashi

Masahiko Ikka

Masatoshi Arai

Yoshihiro Kubota

Yuichi Hamada

Kouichi Yamaguchi

Masaki Kasashima

Yukihiro Kuribayashi

Satoshi Shima

A liquid-liquid extraction unit includes an extraction/separation tank () into which an aqueous phase in bubble form is admitted from an upper inlet () in one sidewall and an organic phase in bubble form is admitted from a lower inlet () in the one sidewall. The upward moving organic phase is contacted with the downward moving aqueous phase. After contact, the organic phase is discharged through an upper outlet () in an opposite sidewall and the aqueous phase is discharged through a lower outlet () in the opposite sidewall.

Liquid-liquid extraction unit, multistage liquid-liquid extraction apparatus using the unit, and multistage continuous extraction system for rare earth elements

The inventive extraction/separation method involves the step of contacting an organic phase containing a dialkyldiglycol amic acid extractant: RRNCOCHOCHCOOH with an aqueous solution containing scandium and zirconium and/or hafnium for thereby extracting zirconium and/or hafnium into the organic phase. The purity of scandium can be efficiently increased by the simple step of solvent extraction.

Extraction/separation method

In an extraction tank, a plating solution containing rare earth metal ions is treated with an extracting solution of an extractant in a water-insoluble organic solvent. Extraction treatment is carried out by atomizing the extracting solution through a lower nozzle into the plating solution in the tank lower zone, and atomizing the plating solution through an upper nozzle into the extracting solution in the tank upper zone, for thereby bringing the plating solution in contact with the extracting solution to extract rare earth metal ions from the plating solution into the extractant for removal.

Method and apparatus for extracting and removing rare earth metal ions from plating solution

A rare earth metal extractant containing, as the extractant component, dialkyldiglycol amide acid which is excellent in breaking down light rare earth elements is reacted in diglycolic acid (X mol) and an esterification agent (Y mol) at a reaction temperature of 70&#xb0; C. or more and for a reaction time of one hour or more such that the mol ratio of Y/X is 2.5 or more, and is subjected to vacuum concentration. Subsequently, a reaction intermediate product is obtained by removing unreacted products and reaction residue. Then a nonpolar or low-polar solvent which is an organic solvent for forming an organic phase during solvent extraction of the rare earth metal and which is capable of dissolving dialkyldiglycol amide acid is added as the reaction solvent, and the reaction intermediate product is reacted with dialkyl amine (Z mol) such that the mol ratio of Z/X is 0.9 or more.

Method for synthesizing rare earth metal extractant

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in an aprotic polar solvent, with a molar ratio of dialkylamine to diglycolic anhydride being at least 1.0, and removing the aprotic polar solvent.

Synthesis of rare earth metal extractant

A rare earth metal extractant containing, as the extractant component, dialkyldiglycol amide acid which is excellent in breaking down light rare earth elements is reacted in diglycolic acid (X mol) and an esterification agent (Y mol) at a reaction temperature of 70&#xb0; C. or more and for a reaction time of one hour or more such that the mol ratio of Y/X is 2.5 or more, and is subjected to vacuum concentration. Subsequently, a reaction intermediate product is obtained by removing unreacted products and reaction residue, and an aprotic polar solvent is added as the reaction solvent. Then, the reaction intermediate product is reacted with dialkyl amine (Z mol) such that the mol ratio of Z/X is 0.9 or more and the aprotic polar solvent is removed. As a consequence, a rare earth metal extractant is efficiently synthesized at a low cost and at a high yield without having to use expensive diglycolic acid anhydride and harmful dichloromethane.

A target light rare earth element is separated from an aqueous solution containing two or more of La, Ce, Pr and Nd by contacting an organic phase containing an extractant with the aqueous solution in a counter-current flow multistage mixer-settler while adding an alkaline solution thereto, and contacting the organic phase with an acid aqueous solution for back-extracting the target element. The extractant is a dialkyl diglycol amic acid having formula: RRNCOCHOCHCOOH wherein Rand Rare alkyl, at least one having at least 6 carbon atoms.

Method for extracting and separating light rare earth element

A rare earth metal extractant in the form of a dialkyl diglycol amic acid is synthesized by reacting diglycolic anhydride with a dialkylamine in a synthesis medium. A molar ratio (B/A) of dialkylamine (B) to diglycolic anhydride (A) is at least 1.0. A non-polar or low-polar solvent in which the dialkyl diglycol amic acid is dissolvable is used as the synthesis medium.

Solvent extraction from an aqueous phase containing first and second rare earth elements is carried out by contacting an organic phase containing a diglycolamic acid as an extractant and a hydrocarbon or a low-polar alcohol as a solvent, with the aqueous phase below pH 3 for extracting the first rare earth element into the organic phase, back-extracting from the organic phase with an aqueous acid solution for recovering the first rare earth element, and recovering the second rare earth element which has not been extracted into the organic phase and has remained in the aqueous phase.

Method for extracting and separating rare earth elements

Provided is an AB,type hydrogen absorbing alloy powder obtained by quenching a melt of a hydrogen absorbing alloy rapidly and subjecting the resulting hydrogen absorbing alloy to fracturing by absorbing hydrogen, wherein the particle size distribution of the hydrogen absorbing alloy powder is such that, when the frequencies of detection of various particle diameters are cumulatively added from smaller-diameter to larger-diameter particles, and the particle diameters corresponding to 10%, 50% and 90% of all particles are represented by D,, D,and D,, respectively, the values of D,, D,and D,fall within the respective ranges defined by 4 &mgr;m&lE;D,&lE;14 &mgr;m, 17 &mgr;m&lE;D,&lE;37 &mgr;m, and 40 &mgr;m&lE;D,&lE;70 &mgr;m.

Hydrogen absorbing alloy powder, process for producing same, and alkaline secondary battery

Provided is an inexpensive process for producing hydrogen absorbing alloy powder suitable for a nickel-metal hydride storage battery having a high rate discharge property, a high capacity and a long cycle life for repetition of charge and discharge. The process comprises a step of an addition of a rare earth metal oxide and/or hydroxide to a hydrogen absorbing alloy powder, a wet or dry mixing step and a thermal treatment step in an inert atmosphere or in a vacuum.

Process for producing hydrogen absorbing alloy powder and hydrogen absorbing alloy electrode

Provided is a hydrogen absorbing alloy powder for use in nickel-metal hydride storage batteries having a high capacity, excellent initial characteristics and a long life. Specifically provided is a process for the production of a hydrogen absorbing alloy powder which includes the steps of treating a hydrogen absorbing alloy powder with an acid solution, and subsequently treating the hydrogen absorbing alloy powder with a solution containing a condensed phosphoric acid having 2 to 20 phosphorus atoms per molecule and/or phytic acid, as well as an electrode formed of the hydrogen absorbing alloy powder produced by the above process. Also provided is a hydrogen absorbing alloy powder of the AB,type in which A is exothermic metal and B is endothermic metal, the hydrogen absorbing alloy powder being obtained by providing a hydrogen absorbing alloy in which A comprises a mixture composed of 20 to 50% by weight of Ce, 20 to 50% by weight of La, and the balance comprising rare earth elements other than Ce and La and inclusive of Y (yttrium), treating the hydrogen absorbing alloy powder with an acid solution, and further treating the hydrogen absorbing alloy powder with a solution containing a phosphorus compound, as well as an electrode formed of this hydrogen absorbing alloy powder.

Hydrogen absorbing alloy powder and electrodes formed of the hydrogen absorbing alloy powder

A hydrogen absorbing alloy electrode having on a conductive support a layer which contains as a main component a hydrogen absorbing alloy powder capable of absorbing and releasing hydrogen electrochemically and is covered with a fluorine-containing water repellent layer on the surface side; with the fluorine-containing water repellent layer being a layer formed by coating and curing a water repellent agent comprising (A) a straight-chain perfluorinated compound having at least two secondary amino groups per molecule and a divalent perfluoroalkylene or perfluoropolyether structure in the main chain and (B) a fluorine-containing epoxy compound having at least three epoxy groups per molecule.

Hydrogen absorbing alloy electrode and method of producing the same

A hydrogen absorbing alloy composition for a nickel-hydrogen secondary battery which includes LnNi.sub.5 hydrogen absorbing alloy, where Ln represents at least one rare-earth element. The hydrogen absorbing alloy composition also includes at least one compound selected from the group consisting of heavy rare-earth oxides, heavy rare-earth hydroxides, compound oxides including at least one rare-earth element and compound hydroxides including at least one rare-earth element. Rare-earth elements can be selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. Exemplary hydrogen absorbing alloy compositions include La alone or in combination with one other rare-earth element, such as Ce, Pr, Nd, or Sm. Exemplary rare-earth oxides include Yb.sub.2 O.sub.3, Er.sub.2 O.sub.3 and GdO.sub.3 and exemplary rare-earth hydroxides include Yb(OH).sub.3 and Er(OH).sub.3.

Hydrogen storage alloy composition and electrode using said alloy

Provided is a hydrogen absorbing alloy electrode having on a conductive support surface a hydrogen absorbing alloy layer which comprises a hydrogen absorbing alloy powder capable of absorbing and desorbing hydrogen electrochemically and a binder; with the hydrogen absorbing alloy layer having a surface coated spotwise with an amorphous water-repelling fluoropolymer at a total coverage of 0.001 mg/cm.sup.2 to 5 mg/cm.sup.2, wherein a solution of the fluoropolymer in a solvent having a boiling point of 50.degree.-110.degree. C. is spray-coated on the alloy layer surface.

Growing community of inventors

Echizen, Japan

Hiroto Sugahara