WO2015122397A1 - Scandium separation method - Google Patents

Scandium separation method Download PDF

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Publication number
WO2015122397A1
WO2015122397A1 PCT/JP2015/053606 JP2015053606W WO2015122397A1 WO 2015122397 A1 WO2015122397 A1 WO 2015122397A1 JP 2015053606 W JP2015053606 W JP 2015053606W WO 2015122397 A1 WO2015122397 A1 WO 2015122397A1
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scandium
organic solvent
aqueous solution
acidic aqueous
acid
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PCT/JP2015/053606
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French (fr)
Japanese (ja)
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芝田　隼次
祐介 植薄
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学校法人 関西大学
石原産業株式会社
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Priority to CN201580002785.9A priority Critical patent/CN105793447B/en
Priority to AU2015216225A priority patent/AU2015216225A1/en
Publication of WO2015122397A1 publication Critical patent/WO2015122397A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
    • C22B3/32—Carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B59/00—Obtaining rare earth metals
    • 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

Definitions

  • the present invention relates to a method for separating scandium (Sc).
  • Scandium is one of the transition metal elements and is classified as a rare earth element together with yttrium (Y).
  • Y yttrium
  • scandium can be used by encapsulating scandium iodide in metal halide lamps, zirconium oxide stabilizers, etc. Zirconia is used as an electrolyte for solid oxide fuel cells.
  • Scandium is a relatively rare metal, and it is contained in tortite, etc., but its output is low, so a small amount of scandium is contained in the leachate that has been leached under pressure by adding sulfuric acid to nickel oxide ore of laterite ore. Are separated.
  • An example of such a scandium separation method is Japanese Patent No. 3428292 (Patent Document 1).
  • Patent Document 1 an organic solvent obtained by diluting 2-ethylhexylsulfonic acid-mono-2-ethylhexyl with kerosene is added to a scandium-containing solution in an aqueous phase, and the scandium component is extracted into the organic solvent. Then, in order to separate the impurity component extracted together with scandium in the organic solvent, scrubbing by adding aqueous hydrochloric acid solution, removing the impurity component, stripping by adding aqueous sodium hydroxide solution in the organic solvent. It is disclosed that the slurry is recovered as a slurry containing scandium hydroxide.
  • Patent Document 1 the recovered scandium hydroxide is dissolved with hydrochloric acid to obtain an aqueous scandium chloride solution, and oxalic acid is added to this to form a scandium oxalate precipitate, the precipitate is filtered, and impurities are separated into the filtrate. Thereafter, it is disclosed that high-purity scandium oxide is obtained by calcination.
  • Patent Document 2 an aqueous solution containing scandium is mixed with an organic solvent containing trioctylphosphine oxide, and scandium is extracted into the organic solvent. Then, the organic solvent is mixed with water, hydrochloric acid, sulfuric acid, oxalic acid.
  • a method for separating and purifying scandium is disclosed in which one or more selected from the above is mixed to back-extract scandium from an organic solvent.
  • Non-Patent Document 1 for various metal elements, by mixing metal nitrate, sodium nitrate and nitric acid and using a carboxylic acid-based extractant such as versatic acid or naphthenic acid, Extraction characteristics of carboxylic acid-based extractants for various metal elements are disclosed.
  • Non-Patent Document 1 mentions scandium as one of various metal elements.
  • Patent Document 1 2-ethylhexylsulfonic acid-mono-2-ethylhexyl is used as an extractant.
  • This extractant extracts many impurities other than scandium. Therefore, in the method of Patent Document 1, a scrubbing process for separating impurities such as yttrium, iron, manganese, chromium, magnesium, aluminum, and calcium is performed.
  • the extractant which extracts many impurities other than scandium is used, since the scrubbing process for isolate
  • the trioctylphosphine oxide used as the extractant in Patent Document 2 has high scandium selectivity, but when a large excess of impurities coexists in the scandium-containing aqueous solution, the scrubbing process is still required, and thus the productivity is high. bad.
  • the coexisting impurity is zirconium, it cannot be sufficiently separated by scrubbing, and it is necessary to remove the zirconium from the scandium-containing aqueous solution in advance using tenoyltrifluoroacetone as an extractant. , Productivity further decreases.
  • Non-Patent Document 1 discloses that scandium nitrate is used as a scandium raw material, scandium nitrate is mixed with sodium nitrate and nitric acid, and a carboxylic acid-based extractant is used. Since scandium nitrate is water soluble, scandium dissolves in sodium nitrate and nitric acid. However, the hardly soluble scandium raw material is difficult to dissolve in sodium nitrate and nitric acid. For this reason, when a hardly soluble material is used as the scandium raw material, even if the poorly soluble scandium raw material is mixed with sodium nitrate and nitric acid, the amount of scandium eluted is small. Therefore, even if a carboxylic acid-based extractant is used, the amount of scandium that can be extracted is small in the first place, and there is a problem that productivity is poor.
  • an object of the present invention is to provide a scandium separation method that improves productivity.
  • the amount of the scandium raw material increased when dissolved in an acidic aqueous solution having a pH of less than 4.
  • the pH was adjusted by mixing with an alkali, and performing contact with an organic solvent containing a carboxylic acid-based extractant, the amount of impurities extracted into the organic solvent is reduced.
  • the present invention was completed by finding that it can be kept low and that scandium can be mainly extracted.
  • the method for separating scandium comprises a step of preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4; By adjusting to the following ranges, the first acidic aqueous solution is brought into contact with the first acidic aqueous solution and an organic solvent containing a carboxylic acid and / or a carboxylate as an extractant.
  • the scandium in the scandium-containing organic solvent is brought into contact by bringing the scandium-containing organic solvent into contact with the second acidic aqueous solution by transferring the scandium in the organic solvent to the scandium-containing organic solvent. To generate a scandium-containing aqueous solution.
  • the method for separating scandium according to one aspect of the present invention further includes a step of bringing a scandium-containing aqueous solution into contact with a precipitation agent to precipitate a scandium compound.
  • the method for separating scandium includes a step of preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4, and an acidic aqueous stock solution and an alkali, so that the pH is 4 or more and 7
  • the first acidic aqueous solution is brought into contact with the first acidic aqueous solution and an organic solvent containing a carboxylic acid and / or a carboxylate as an extractant.
  • the method includes a step of generating a scandium-containing organic solvent by moving scandium therein to an organic solvent, and a step of bringing a scandium-containing organic solvent into contact with a precipitation agent to generate a scandium compound.
  • the precipitating agent is a carboxylic acid and / or a carboxylate.
  • the method for separating scandium according to one aspect and the other aspect of the present invention further includes a step of drying and / or firing the scandium compound.
  • the extractant is naphthenic acid and / or neodecanoic acid.
  • the organic solvent preferably further includes a modifier.
  • the modifier is tributyl phosphate.
  • the acidic aqueous solution further contains at least one metal ion selected from rare earth elements other than titanium, zirconium, vanadium, and scandium.
  • the acidic aqueous stock solution is preferably an aqueous solution in which ore and / or residue of the ore are dissolved with an acid.
  • the acidic aqueous stock solution is an aqueous solution in which an aqueous slurry containing scandium and an acid are mixed to adjust the pH to 2 or less.
  • the scandium separation method of the present invention by preparing an acidic aqueous stock solution having a pH of less than 4, the amount of elution of the scandium raw material can be increased, and the acidic aqueous stock solution and alkali are mixed to adjust the pH. After adjusting to the range of 4 or more and 7 or less, by contacting with an organic solvent containing carboxylic acid and / or carboxylate as an extractant, scandium is transferred to the organic solvent to reduce impurities in the organic solvent. be able to. Therefore, the present invention can provide a scandium separation method that improves productivity.
  • Embodiment 1 of this invention It is a flowchart which shows the separation method of the scandium of Embodiment 1 of this invention. It is the schematic diagram in each process in the separation method of scandium of Embodiment 1 of this invention.
  • Embodiment 2 of the present invention is a flowchart showing a method for separating scandium. It is the schematic diagram in each process in the separation method of scandium of Embodiment 2 of this invention.
  • an acidic aqueous stock solution containing scandium and having a pH of less than 4 is prepared (step S1: preparation step).
  • the acidic aqueous stock solution is not particularly limited as long as it contains scandium, and examples thereof include an acidic aqueous solution containing scandium ions, an acidic aqueous solution containing scandium such as a slurry containing scandium hydroxide and scandium oxide, and the like.
  • the pH of the acidic aqueous stock solution is less than 4, preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less from the viewpoint of quality stability.
  • the acidic aqueous stock solution contains rare earth elements other than scandium (yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium).
  • rare earth elements other than scandium yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.
  • transition metal elements such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, thorium
  • radioactive elements such as uranium, other alkali metal elements, alkaline earth metal elements, group 12 elements of the periodic table such as zinc and cadmium, boron, aluminum, gallium, indium, etc.
  • Periodic group 13 element, periodic table group 14 element such as silicon, germanium, tin, periodic table group 15 element such as phosphorus, arsenic, antimony, bismuth, periodic table group 16 element such as selenium, tellurium, fluorine
  • a typical element such as a group 17 element of the periodic table such as chlorine may be included.
  • an acidic aqueous stock solution containing at least one metal ion selected from titanium, zirconium, vanadium, and a rare earth element other than scandium is preferably used because the effect is easily obtained.
  • the concentration of scandium in the acidic aqueous stock solution is not particularly limited, and is preferably high in terms of yield, more preferably about 500 to 50,000 mg / L.
  • the scandium concentration may be low.
  • scandium can be separated by the separation method of the present embodiment even at about 10 to 500 mg / L.
  • the concentration of elements (impurities) other than scandium in the acidic aqueous stock solution there is no particular limitation on the concentration of elements (impurities) other than scandium in the acidic aqueous stock solution, but in order to facilitate the separation of scandium, there are few impurity components and those with low concentrations are preferred.
  • the acidic aqueous stock solution contains titanium, zirconium and vanadium, each is preferably about 1000 mg / L or less, and more preferably 0 mg / L.
  • the acidic aqueous solution contains a rare earth element other than scandium, it is more preferably about 1000 mg / L or less, and even more preferably 0 mg / L.
  • the acidic aqueous stock solution is prepared by using an acidic aqueous solution containing scandium, using an acidic aqueous solution obtained by roughly purifying the solution, or preparing an acidic aqueous solution by mixing an acid with a slurry containing scandium hydroxide, scandium oxide, or the like. Ready.
  • the acidic aqueous stock solution for example, the following acidic aqueous solution can be used. From the viewpoint of containing a large amount of scandium, an aqueous solution obtained by dissolving ore with an acid and / or an aqueous solution obtained by dissolving an ore residue with an acid is preferable.
  • An aqueous solution prepared by mixing the aqueous slurry containing the acid and adjusting the pH to 2 or less is more preferable.
  • Acidic aqueous solution in which materials such as ores containing scandium are dissolved with acid (2) After refining other metal components by hydrolyzing or neutralizing a solution in which materials such as ores containing scandium are dissolved in acids Acidic aqueous solution or acidic aqueous solution in which the residue after refining other metal components is dissolved with acid (3) After reducing impurities by dissolving materials such as ores containing scandium with alkali in advance, the material with reduced impurities (4) Acidic aqueous solution obtained by roughly purifying scandium by adsorbing and eluting the scandium contained in the acidic aqueous solutions (1) to (3) above with an ion exchange resin or by separating the precipitates by precipitation.
  • the scandium contained in the acidic aqueous solution of (1) to (3) above is adsorbed and eluted with an ion exchange resin, or precipitated and separated.
  • Acidic aqueous solution obtained by mixing acid with slurry containing indium, scandium oxide, etc.
  • the material containing scandium may be water-soluble or sparingly soluble (including insoluble). Ores, other residues after refining other metal components from ores, aluminum alloys containing scandium, anodes of nickel / alkaline batteries, metal halide lamps, solid oxide fuel cell electrolytes, scandia stabilized zirconia ceramics, etc.
  • Various materials and wastes such as can be used.
  • tortue bait gold ore, silver ore, copper ore, lead ore, bismuth ore, tin ore, antimony ore, mercury ore, zinc ore, iron ore, chromium ore, manganese ore, tungsten ore, molybdenum ore Arsenic ore, nickel ore, cobalt ore, uranium ore, thorium ore, phosphorus ore, sulfur ore, barium ore, calcium ore, magnesium ore, strontium ore, beryllium ore, aluminum ore, titanium ore etc., iron ore, Ores containing a large amount of scandium such as nickel ore, titanium ore, manganese ore, tin ore and aluminum ore are preferred.
  • An acid that dissolves a material such as ore or an acid that is adjusted to be acidic can be used without limitation, and inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, and aqua regia, and organic acids such as acetic acid can be used.
  • inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, and aqua regia
  • organic acids such as acetic acid
  • the liquid after refining other metal components by hydrolyzing or neutralizing the liquid in which the material such as ore is dissolved with an acid is used as the acid that dissolves the material such as ore or the acid that is adjusted to be acidic. It can also be used.
  • a liquid after refining such other metal components for example, a leachate obtained by adding sulfuric acid to a nickel oxide ore of laterite ore and leaching under pressure
  • a liquid after taking out the nickel component from the leachate Can be used.
  • the liquid after neutralizing and taking out the titanium component and the iron component can be used as an acid for dissolving materials such as ore or an acid for adjusting the acidity.
  • dissolved the residue after chlorinating and extracting other metals in an ore with an acid can be used as an acid which dissolves materials, such as an ore, or an acid which adjusts to acidity, for example, a rutile ore Titanium ores such as iron ore and iron ore are chlorinated with chlorine gas, and the residue after taking out titanium chloride and iron chloride is made of inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, aqua regia, and organic acids such as acetic acid.
  • a solution dissolved with an acid, a solution obtained by hydrolyzing the solution and taking out a titanium component and an iron component, and the like can be used.
  • alkali that dissolve materials such as ores can be used without limitation, for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, ammonia, amines Etc. can be used.
  • Acids that adjust the pH to acidic after dissolving materials such as ores with alkali can be used without limitation, and use inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, aqua regia, and organic acids such as acetic acid.
  • inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, aqua regia, and organic acids such as acetic acid.
  • An acidic aqueous solution in which materials such as the above ores are dissolved may be used.
  • the above-mentioned acidic aqueous solution is used to adsorb the scandium contained in the conventional method, for example, with an ion exchange resin, and then precipitate by elution from the ion exchange resin or pH adjustment.
  • the concentration of scandium can be increased by dispersing scandium hydroxide, scandium oxide, or the like obtained by the separation treatment in water.
  • a solution whose pH is adjusted to less than 4 by adding the roughly purified solution and the acid can also be used as the acidic aqueous stock solution.
  • Step S2 pH). Adjustment process
  • the first acidic aqueous solution obtained by carrying out this step is composed of Sc (OH) 3 present as hydroxide, Sc 3+ present as ions, and an acidic aqueous stock solution. And impurities from.
  • step S2 by setting the pH to 4 or more and 7 or less, scandium is mainly extracted in the organic solvent extraction step (step S3) described later, and impurity extraction can be reduced. If the pH is less than 4, the amount of scandium extracted is greatly reduced, and the yield of separable scandium is reduced. If the pH is higher than 7, the amount of extracted impurities increases in the organic solvent extraction step (step S3) described later, and the scandium separation efficiency decreases. From this viewpoint, it is preferable to adjust the pH to a range of 5 or more and 7 or less. Specifically, it is preferable to adjust the pH to a range of 5.0 or more and 6.5 or less, and 6.0 or more and 6.5 or less. It is more preferable to adjust to this range.
  • the alkali for adjusting the pH can be used without limitation as long as it exhibits alkalinity, and may be solid or liquid.
  • alkalis include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, magnesium hydroxide and barium hydroxide, ammonia and amines. be able to.
  • step S3 organic solvent extraction step. Specifically, in this step S3, an organic solvent containing carboxylic acid and / or a salt thereof as an extractant is mixed with a first acidic aqueous solution, and a complex formed from scandium and the extractant is used as the organic solvent. Extract.
  • Step S3 an organic solvent containing scandium (scandium-containing organic solvent) and a first acidic aqueous solution that no longer contains scandium (first acidic aqueous solution after extraction) are generated. Since the scandium in the organic solvent and the carboxylic acid-based extractant form a complex of scandium carboxylate, and this complex is soluble in the organic solvent, the complex moves to the organic solvent.
  • the scandium-containing organic solvent contains scandium carboxylate produced by the extractant in the organic solvent and the scandium ions in the first acidic aqueous solution, and impurities. However, most of the impurities remain in the first acidic aqueous solution after extraction, and the impurities that move into the scandium-containing organic solvent are less than the impurities in the first acidic aqueous solution in the pH adjustment step (step S2).
  • Carboxylic acid is an organic compound having a carboxy group, and carboxylate is formed by reaction of a salt such as sodium, potassium or ammonium with the carboxyl group of carboxylic acid.
  • the carboxylic acid-based extractant is not particularly limited as long as it forms a complex with scandium.
  • known extractants such as neodecanoic acid (versaic acid-based), naphthenic acid-based, oleic acid-based, and lauric acid-based extractants From the viewpoint that scandium can be extracted more effectively, naphthenic acid and / or neodecanoic acid is preferably used.
  • the proportion of the carboxylic acid-based extractant can be appropriately set, and is preferably 1 to 50% by mass, more preferably 5 to 20% by mass with respect to the organic solvent.
  • a modifier may be added to the organic solvent.
  • the modifying agent include long-chain alkyl compounds such as nonylphenol, 1-decanol, isodecanol, 1-octanol, 2-ethylhexanol, tributyl phosphate (TBP), trioctyl phosphate (TOP), trioctylphosphine oxide (TOPO).
  • alkyl phosphate compounds such as), amines such as primary amines, secondary amines, tertiary amines, and quaternary ammonium salts. Since not only the third phase generation can be suppressed but also the back-extraction step (step S4) described later can improve the recovery rate of scandium, tributyl phosphate is preferably used.
  • the addition amount of the modifier can be appropriately set and is preferably 1 to 50% by mass, more preferably 5 to 40% by mass with respect to the organic solvent.
  • the solvent extraction operation of scandium is carried out by using a known liquid-liquid contact apparatus, a carboxylic acid-based extractant and, if necessary, an organic solvent containing a modifier and an acidic aqueous undiluted solution at a suitable temperature for a certain period of time.
  • a known liquid-liquid contact apparatus a carboxylic acid-based extractant and, if necessary, an organic solvent containing a modifier and an acidic aqueous undiluted solution at a suitable temperature for a certain period of time.
  • the liquid-liquid contact device include a centrifugal extractor, a mixer, a shaker, a separatory funnel, a multistage liquid-liquid contact device, more specifically, a countercurrent multistage mixer-settler extractor, a continuous method and Any of batch methods may be used.
  • the treatment temperature is preferably set so as to maintain the temperature of the acidic aqueous undiluted solution and the extractant before the extraction operation, but from the viewpoint of the flash point of the organic solvent, the phase separation rate, the stability of the extractant phase, etc.
  • the temperature is preferably maintained at 20 to 70 ° C.
  • the solvent extraction is not limited to once, and may be performed in several steps.
  • the organic solvent can be used without any particular limitation.
  • Aromatic hydrocarbon compounds such as toluene and p-chlorotoluene; kerosene, n-pentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, n-decane, n-dodecane, cyclohexane, Chloroform, tetrachloromethane, chloroethane, 1,1-dichloroethane, 1,2-
  • Step S4 back extraction step. Specifically, in step S4, an organic solvent containing scandium (scandium-containing solvent) extracted in the organic solvent extraction step (step S3) and the second acidic aqueous solution are mixed, and the scandium is converted into the second acidic aqueous solution. Extract and purify and concentrate.
  • the 2nd acidic aqueous solution (scandium containing aqueous solution) containing scandium and the organic solvent (organic solvent after back extraction) which no longer contains scandium are produced
  • the scandium-containing aqueous solution contains scandium ions generated from scandium in the scandium-containing organic solvent by the second acidic aqueous solution and some impurities in the scandium-containing organic solvent. Impurities in the scandium-containing aqueous solution are less than or comparable to those in the scandium-containing organic solvent in the organic solvent extraction step (step S3). That is, the impurities in the scandium-containing aqueous solution are less than the impurities in the acidic aqueous stock solution in the preparation step (step S1) and the first acidic aqueous solution in the pH adjustment step (step S2).
  • an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid, or an organic acid such as acetic acid
  • the scandium back-extraction operation uses a liquid-liquid contact device to bring the organic solvent and the second acidic aqueous solution into contact with each other at a suitable temperature for a certain period of time using a known procedure, and then to the aqueous phase by stationary separation or centrifugation. It can be performed by separating into (scandium-containing aqueous solution) and an organic phase (an organic solvent after back extraction).
  • liquid-liquid contact apparatus examples include a centrifugal extractor, a mixer, a shaker, a separatory funnel, a multistage liquid-liquid contact apparatus, and more specifically, a countercurrent multistage mixer-settler extractor and a centrifugal extractor. Any of a continuous method and a batch method may be used.
  • the back extraction is not limited to once, and may be performed in several steps.
  • the organic solvent extraction step (step S3) and the back extraction step (step S4) are not limited to once, and it is preferable because the concentration of scandium can be increased by repeating several times.
  • the purity of scandium is, for example, 99.0% by mass or more, and preferably 99.5% by mass or more. it can.
  • a scandium containing aqueous solution and a precipitation agent are made to contact, and a scandium compound is deposited (step S5: precipitation process).
  • scandium is precipitated by mixing the scandium-containing aqueous solution back-extracted in the back extraction step (step S4) and the aqueous solution containing the precipitation agent, and scandium is recovered as a precipitate.
  • the scandium in the scandium-containing aqueous solution reacts with the precipitation agent, and a scandium compound as a precipitate is generated.
  • Impurities in the scandium-containing aqueous solution are maintained in the mixed solution, the impurities contained in the scandium-containing aqueous solution are reduced, so that the impurities contained in the precipitate can be reduced.
  • Impurities are basically present as ions in the mixed solution.
  • the precipitating agent is not particularly limited as long as it precipitates scandium. From the viewpoint of easy precipitation of scandium, it may be a carboxylic acid and / or a carboxylate salt (hereinafter also referred to as a carboxylic acid-based precipitating agent). preferable.
  • the precipitation agent made to contact with a scandium containing aqueous solution may be used in a solid state, and may be used as an aqueous solution containing a precipitation agent.
  • carboxylic acid-based precipitants include formic acid (methanoic acid), acetic acid (ethanoic acid), propionic acid (propanoic acid), butyric acid (butanoic acid), valeric acid (pentanoic acid), caproic acid (hexanoic acid), and enanthic acid (Heptanoic acid), fatty acids such as caprylic acid (octanoic acid), hydroxy acids such as lactic acid (2-hydroxypropanoic acid), malic acid (2-hydroxybutanedioic acid), citric acid (2-hydroxypropanetricarboxylic acid), Oxalic acid (ethanedioic acid), malonic acid (propanedioic acid), succinic acid (butanedioic acid) glutaric acid (pentanedioic acid), adipic acid (hexanedioic acid), fumaric acid ((E) -but-2- Dicarboxylic acids such as enedi
  • the precipitating agent is not particularly limited to a carboxylic acid precipitant, and may be a carbonate such as carbon dioxide, ammonium carbonate, or sodium carbonate, or an alkali salt such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide. .
  • the ratio of the carboxylic acid type precipitation agent to scandium is preferably 1.0 to 5.0 mol, and more preferably 1.5 to 3.0 mol.
  • the scandium and the precipitating agent are brought into contact with each other at a suitable temperature for a certain period of time by a known procedure using a precipitation apparatus.
  • the obtained precipitate is a scandium compound
  • the precipitate when a carboxylic acid type precipitation agent is used is a compound of scandium carboxylate.
  • the scandium compound is collected by separation as necessary.
  • the fractionation operation can be performed with a normal apparatus, and a filter, a stationary separator, a centrifuge, or the like can be used.
  • the purity of scandium can be set to 99.3% by mass or more, for example. May be 99.7% by mass or more, more preferably 99.9% by mass.
  • scandium can be separated with high purity from an acidic aqueous stock solution containing thorium, uranium and the like.
  • step S6 drying / baking step
  • the precipitate obtained in the precipitation step (step S5) can be recovered as a powder such as scandium oxide by drying and / or firing. Note that this step (step S6) may be omitted.
  • the drying conditions and / or firing conditions can be set as appropriate.
  • the drying temperature is suitably about 80 to 150 ° C.
  • the drying time is suitably about 1 to 24 hours.
  • the firing temperature is about 300 to 1200 ° C., and the firing time is about 1 to 24 hours.
  • step S2 the reaction mechanism in the pH adjustment step (step S2) and the organic solvent extraction step (step S3) will be described.
  • step S2 when an acidic aqueous stock solution and an alkali are mixed to adjust the pH to 4 or more and 7 or less, a precipitation reaction to the right side of the following chemical formula 1 occurs.
  • step S3 In the extraction of scandium using a carboxylic acid-based extractant in the organic solvent extraction step (step S3), as shown in the following chemical formula 2, the scandium ion and the carboxylic acid-based extractant form a complex.
  • Sc 3+ + 3HA ⁇ ScA 3 + 3H + (chemical formula 2)
  • HA is an extractant having a proton (H + )
  • A is an alkyl group containing carbon
  • a ⁇ in the case of neodecanoic acid is C 9 H 19 COO ⁇ .
  • the first acidic aqueous solution and alkali are mixed to adjust the pH of the first acidic aqueous solution to 4 or more, so that the right side in Chemical Formula 2 Promotes reaction to
  • the first acidic aqueous solution and alkali are mixed to adjust the pH of the first acidic aqueous solution to 7 or less.
  • the method for separating scandium in the present embodiment includes a step of preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4 (step S1), and mixing the acidic aqueous stock solution and an alkali.
  • producing a scandium-containing aqueous solution by moving scandium in the scandium-containing organic solvent to the second acidic aqueous solution.
  • an acidic aqueous stock solution having a pH of less than 4 is prepared as a raw material containing scandium in the preparation step (step S1). For this reason, even if a sparingly soluble scandium raw material is used, it can be dissolved as scandium ions in the acidic aqueous stock solution, so that a decrease in the content of scandium in the acidic aqueous stock solution can be suppressed.
  • the pH is adjusted to a range of 4 to 7 using an alkali before the organic solvent extraction step (step S3), and naphthenic acid,
  • a carboxylic acid such as neodecanoic acid and / or a salt thereof
  • extraction of impurities such as titanium, zirconium, vanadium, and rare earth elements other than scandium can be suppressed to a low level.
  • this effect is an effect found by conceiving the knowledge of the reaction mechanism in the pH adjustment step (step S2) and the organic solvent extraction step (step S3) described above.
  • scandium can be transferred to the second acidic aqueous solution by bringing the extracted scandium-containing organic solvent containing scandium into contact with the second acidic aqueous solution such as sulfuric acid or hydrochloric acid. Therefore, productivity can be improved and scandium can be separated.
  • the scandium separation method of the present embodiment preferably further includes a step (step S5) of bringing a scandium-containing aqueous solution and a precipitating agent into contact with each other to precipitate a scandium compound.
  • step S5 the scandium-containing aqueous solution obtained in the back extraction step (step S4) can be mixed with a carboxylic acid such as oxalic acid and / or a salt thereof as a precipitating agent to precipitate a scandium compound. It can improve and separate scandium.
  • the scandium separation method of the present embodiment preferably further includes a step of drying and / or firing the scandium compound (step S6). Thereby, it can collect
  • a coprecipitate can be formed by mixing the scandium-containing aqueous solution separated by performing the back extraction step (step S4) and the zirconium aqueous solution, and calcined to produce scandia-stabilized zirconia.
  • the scandium separated by carrying out the drying / firing step (step S6) is a powder such as scandium hydroxide or scandium oxide
  • the powder is mixed with zirconium oxide and fired to obtain scandia-stabilized zirconia.
  • scandium separation method of the present embodiment scandium can be separated so as to increase the purity by reducing impurities while improving productivity. That is, according to the scandium separation method of the present embodiment, scandium can be purified with high efficiency and ease.
  • scandia-stabilized zirconia using scandium obtained according to the present embodiment is useful for an electrolyte of a solid oxide fuel cell. Further, scandium oxide can be reduced to a metal, and iodide can be obtained. It can also be used as a compound such as scandium iodide.
  • step S1 preparation step. Since this step S1 is the same as that of Embodiment 1, the description thereof will not be repeated.
  • a first acidic aqueous solution is generated by mixing the acidic aqueous stock solution and the alkali and adjusting the pH to a range of 4 or more and 7 or less (step S2: pH). Adjustment process). Since this step S2 is the same as that of Embodiment 1, the description thereof will not be repeated.
  • step S3 organic solvent extraction step
  • the back extraction step (step S4: back extraction step) of Embodiment 1 is omitted, and then, as shown in FIGS. 3 and 4, the scandium-containing organic solvent is contacted with the precipitation agent.
  • step S5 precipitation step
  • an organic solvent containing extracted scandium and a precipitant are mixed to precipitate scandium.
  • the scandium in the scandium-containing organic solvent reacts with the precipitation agent to obtain a scandium compound.
  • the back extraction process (step S4) of the present embodiment is different from the first embodiment in that the object to be contacted with the precipitation agent is a scandium-containing organic solvent, and the other processes are the same as in the first embodiment.
  • step S6 drying / baking step. Since this step S6 is the same as that of Embodiment 1, the description thereof will not be repeated. This step S6 may be omitted.
  • step S6 By performing the above steps (steps S1 to S3, S5, S6), productivity can be improved and scandium can be separated.
  • the purity of scandium is, for example, 99.0% by mass or more. , Preferably it can be 99.5 mass% or more.
  • step S1 an acidic aqueous undiluted solution in which scandium hydroxide containing impurities is dispersed in water, sulfuric acid is added to adjust the pH to 1.0, and the scandium is dissolved by heating at 90 ° C. for 3 hours.
  • step S2 sodium hydroxide was added to the acidic aqueous stock solution to adjust to pH 6.5 (first acidic aqueous solution: sample A).
  • step S3 100 mL of this acidic aqueous stock solution (aqueous phase), neodecanoic acid (extractant), and tributyl phosphate (modifier) at concentrations of 10% by mass and 30% by mass, respectively. Then, 100 mL of an organic solvent dissolved in kerosene was placed in a 500 mL separatory funnel and mixed with a vertical shaker for 20 minutes to extract scandium. After shaking, the separatory funnel was allowed to stand to separate into an organic phase (scandium-containing organic solvent) and an aqueous phase (first acidic aqueous solution after extraction).
  • organic phase scandium-containing organic solvent
  • aqueous phase first acidic aqueous solution after extraction
  • step S4 As a back extraction step (step S4), 80 mL of the organic phase from which scandium was extracted (scandium-containing organic solvent) and 20 mL of 2M sulfuric acid (second acidic aqueous solution) were placed in a 500 mL separatory funnel, and a vertical shaker for 20 minutes And back-extracted scandium. After shaking, the separatory funnel was allowed to stand, and the organic phase (organic solvent after back extraction) and the aqueous phase (scandium-containing aqueous solution: sample B) were separated.
  • the organic phase organic solvent after back extraction
  • aqueous phase scandium-containing aqueous solution: sample B
  • step S1 an acidic aqueous stock solution in which scandium hydroxide containing impurities is dispersed in water, hydrochloric acid is added to adjust the pH to 1.0, and the scandium is dissolved by heating at 90 ° C. for 3 hours.
  • step S2 sodium hydroxide was added to the aqueous solution to adjust to pH 6.0.
  • the organic solvent extraction step (step S3) and the back extraction step (step S4) are performed to extract scandium and back extract, and the aqueous phase (first acidic aqueous solution before extraction) is extracted.
  • Sample C) and an aqueous phase after back extraction were obtained.
  • Elemental concentrations were analyzed with an inductively coupled plasma emission spectrometer (ICP-AES) and an inductively coupled plasma mass spectrometer (ICP-MS), respectively. The results are shown in Table 3 and Table 4, respectively.
  • Example 3 In Example 3, the precipitation step (Step S5) was further performed. Specifically, the scandium-containing aqueous solution of Sample B of Example 1 and Sample D of Example 2 and oxalic acid (1.5 mol times with respect to scandium) as a precipitating agent were mixed in a reaction vessel to obtain a scandium compound. As a result, scandium oxalate was deposited.
  • scandia-stabilized zirconia can be produced by treating the scandium oxalate precipitate obtained in Example 3, its dried product, and calcined scandium oxide by a known method. Furthermore, they have been confirmed to act as electrolytes for solid oxide fuel cells.
  • step S1 scandium hydroxide containing impurities was dispersed in water, and sulfuric acid was added to adjust the pH to 0.5 to dissolve scandium.
  • aqueous ammonia was added to adjust the pH to 2.5, and the mixture was heated at 90 ° C. for 1 hour to precipitate impurities such as titanium as hydroxides. This was filtered, and the filtrate was collected to obtain an acidic aqueous stock solution.
  • step S2 ammonia water was added to the acidic aqueous stock solution to adjust to pH 6.5 (first acidic aqueous solution: sample G).
  • step S3 As an organic solvent extraction step (step S3), 15 mL of this acidic aqueous stock solution (aqueous phase), neodecanoic acid (extractant), and tributyl phosphate (modifier) at concentrations of 10% by mass and 30% by mass, respectively. Then, 15 mL of an organic solvent dissolved in kerosene was placed in a 50 mL centrifuge tube and mixed with a vertical shaker for 20 minutes to extract scandium. After shaking, the centrifuge tube was allowed to stand and separated into an organic phase (scandium-containing organic solvent) and an aqueous phase (first acidic aqueous solution after extraction: sample H).
  • an organic phase scandium-containing organic solvent
  • aqueous phase first acidic aqueous solution after extraction: sample H.
  • step S4 As a back extraction step (step S4), 10 mL of the organic phase from which scandium was extracted (scandium-containing organic solvent) and 10 mL of 0.4N hydrochloric acid (second acidic aqueous solution) were placed in a 50 mL centrifuge tube and shaken vertically for 20 minutes. Mix in the machine and back-extract scandium. After shaking, the centrifuge tube was allowed to stand, and the organic phase (organic solvent after back extraction) and the aqueous phase (scandium-containing aqueous solution: sample I) were separated.
  • organic phase organic solvent after back extraction
  • aqueous phase scandium-containing aqueous solution: sample I
  • step S3 As in Examples 1 and 2, it was found that by performing the organic solvent extraction step (step S3) and the back extraction step (step S4), the impurity element was separated, and scandium could be separated with high accuracy. Further, the scandium recovery rate in the back extraction process was as high as about 90%.
  • Example 5 In the organic solvent extraction step (step S3), a preparation step (same as in Example 4) except that only neodecanoic acid (extractant) dissolved in kerosene so as to have a concentration of 10% by mass is used as the organic solvent.
  • Step S1 pH adjustment step (Step S2), organic solvent extraction step (Step S3), back extraction step (Step S4) are carried out, first acidic aqueous solution (sample J) after extraction and scandium containing after back extraction An aqueous solution (Sample K) was obtained.
  • ICP-AES inductively coupled plasma emission spectrometer
  • ICP-MS inductively coupled plasma mass spectrometer
  • the scandium separated by the scandium separation method of the present invention can be used in various applications because it is separated with improved productivity and is low in impurities and high in purity. Specifically, scandia-stabilized zirconia and the like useful for an electrolyte of a solid oxide fuel cell can be produced.

Abstract

This scandium separation method comprises: a step (step S1) in which an acidic water-soluble solution having a pH of less than 4 and containing scandium is prepared; a step (step S2) in which a first acidic water-soluble fluid is generated by mixing the acidic water-soluble solution and an alkali and adjusting the pH to a range of 4-7; a step (step S3) in which a scandium-containing organic solvent is generated by bringing into contact with each other the first acidic water-soluble fluid and an organic solvent including, as an extracting agent, carboxylic acid and/or carboxylate, and transferring the scandium in the first acidic water-soluble fluid to the organic solvent; and a step (step S4) in which a scandium-containing water-soluble fluid is generated by brining into contact with each other the scandium-containing organic solvent and a second acidic water-soluble fluid and transferring the scandium in the scandium-containing organic solvent to the second acidic water-soluble fluid.

Description

スカンジウムの分離方法Scandium separation method
　本発明は、スカンジウム（Ｓｃ）の分離方法に関する。 The present invention relates to a method for separating scandium (Sc).
　スカンジウムは、遷移金属元素の一つで、イットリウム（Ｙ）と共に希土類元素に分類される。スカンジウムは、例えばアルミニウム合金の添加剤、ニッケル・アルカリ蓄電池の陽極の改良剤のほかに、ヨウ化スカンジウムをメタルハライドランプに封入して用いたり、酸化ジルコニウムの安定化剤等に用いられ、スカンジア安定化ジルコニアは固体酸化物燃料電池の電解質に利用されている。 Scandium is one of the transition metal elements and is classified as a rare earth element together with yttrium (Y). For example, in addition to aluminum alloy additives and nickel / alkaline battery anode improvers, scandium can be used by encapsulating scandium iodide in metal halide lamps, zirconium oxide stabilizers, etc. Zirconia is used as an electrolyte for solid oxide fuel cells.
　スカンジウムは比較的希少な金属であり、トルトベイト石等に含まれているが産出量が少ないため、ラテライト鉱のニッケル酸化鉱等に硫酸を添加し加圧浸出した浸出液に含まれている微量のスカンジウムを分離している。このようなスカンジウムの分離方法として、例えば特許第３４２８２９２号（特許文献１）が挙げられる。 Scandium is a relatively rare metal, and it is contained in tortite, etc., but its output is low, so a small amount of scandium is contained in the leachate that has been leached under pressure by adding sulfuric acid to nickel oxide ore of laterite ore. Are separated. An example of such a scandium separation method is Japanese Patent No. 3428292 (Patent Document 1).
　具体的には、特許文献１には、水相の含スカンジウム溶液に、２－エチルヘキシルスルホン酸－モノ－２－エチルヘキシルをケロシンで希釈した有機溶媒を加えて、スカンジウム成分を有機溶媒中に抽出し、次いで、有機溶媒中にスカンジウムと共に抽出された不純物成分を分離するために、塩酸水溶液を加えてスクラビングを行い、不純物成分を除去した後、有機溶媒中に水酸化ナトリウム水溶液を加えてストリッピングして、水酸化スカンジウムを含むスラリーとして回収していることが開示されている。さらに、特許文献１には、回収した水酸化スカンジウムを塩酸で溶解し、塩化スカンジウム水溶液を得、これにシュウ酸を加えてシュウ酸スカンジウム沈殿とし、沈殿を濾過し、不純物を濾液中に分離した後、仮焼することにより高純度な酸化スカンジウムを得ることが開示されている。 Specifically, in Patent Document 1, an organic solvent obtained by diluting 2-ethylhexylsulfonic acid-mono-2-ethylhexyl with kerosene is added to a scandium-containing solution in an aqueous phase, and the scandium component is extracted into the organic solvent. Then, in order to separate the impurity component extracted together with scandium in the organic solvent, scrubbing by adding aqueous hydrochloric acid solution, removing the impurity component, stripping by adding aqueous sodium hydroxide solution in the organic solvent. It is disclosed that the slurry is recovered as a slurry containing scandium hydroxide. Further, in Patent Document 1, the recovered scandium hydroxide is dissolved with hydrochloric acid to obtain an aqueous scandium chloride solution, and oxalic acid is added to this to form a scandium oxalate precipitate, the precipitate is filtered, and impurities are separated into the filtrate. Thereafter, it is disclosed that high-purity scandium oxide is obtained by calcination.
　また、特許文献２には、スカンジウムを含む水溶液に、トリオクチルホスフィンオキシドを含む有機溶媒を混合して、スカンジウムを有機溶媒中に抽出した後、この有機溶媒と、水、塩酸、硫酸、シュウ酸から選ばれる一種以上とを混合して、スカンジウムを有機溶媒から逆抽出する、スカンジウムの分離精製方法が開示されている。 In Patent Document 2, an aqueous solution containing scandium is mixed with an organic solvent containing trioctylphosphine oxide, and scandium is extracted into the organic solvent. Then, the organic solvent is mixed with water, hydrochloric acid, sulfuric acid, oxalic acid. A method for separating and purifying scandium is disclosed in which one or more selected from the above is mixed to back-extract scandium from an organic solvent.
　一方、非特許文献１には、種々の金属元素について、硝酸金属と、硝酸ナトリウム及び硝酸とを混合して、バーサティック酸、ナフテン酸等のカルボン酸系抽出剤を用いることにより、平衡ｐＨにおける種々の金属元素に対するカルボン酸系抽出剤の抽出特性が開示されている。非特許文献１には、種々の金属元素の１つとして、スカンジウムが挙げられている。 On the other hand, in Non-Patent Document 1, for various metal elements, by mixing metal nitrate, sodium nitrate and nitric acid and using a carboxylic acid-based extractant such as versatic acid or naphthenic acid, Extraction characteristics of carboxylic acid-based extractants for various metal elements are disclosed. Non-Patent Document 1 mentions scandium as one of various metal elements.
特許第３４２８２９２号公報Japanese Patent No. 3428292 特開２０１４－１４３０号公報JP 2014-1430 A
　上記特許文献１では、抽出剤として２－エチルヘキシルスルホン酸－モノ－２－エチルヘキシルを用いている。この抽出剤は、スカンジウム以外の不純物を多く抽出してしまう。そのため、特許文献１の方法では、イットリウム、鉄、マンガン、クロム、マグネシウム、アルミニウム、カルシウム等の不純物を分離するスクラビング工程を行っている。このように、上記特許文献１では、スカンジウム以外の不純物を多く抽出してしまう抽出剤を用いているので、不純物を分離するためのスクラビング工程が必要であるため、生産性が悪いという問題がある。 In Patent Document 1 above, 2-ethylhexylsulfonic acid-mono-2-ethylhexyl is used as an extractant. This extractant extracts many impurities other than scandium. Therefore, in the method of Patent Document 1, a scrubbing process for separating impurities such as yttrium, iron, manganese, chromium, magnesium, aluminum, and calcium is performed. Thus, in the said patent document 1, since the extractant which extracts many impurities other than scandium is used, since the scrubbing process for isolate | separating an impurity is required, there exists a problem that productivity is bad. .
　また、上記特許文献２で抽出剤に用いるトリオクチルホスフィンオキシドはスカンジウムの選択性が高いが、スカンジウム含有水溶液に大過剰の不純物が共存する場合には、やはり、スクラビング工程を要するので、生産性が悪い。特に、共存する不純物がジルコニウムであると、スクラビングでも十分にジルコニウムを分離できず、テノイルトリフルオルアセトンを抽出剤に用いて、予め、スカンジウム含有水溶液からジルコニウムを除去しておくことが必要であり、生産性が一層低下する。 Further, the trioctylphosphine oxide used as the extractant in Patent Document 2 has high scandium selectivity, but when a large excess of impurities coexists in the scandium-containing aqueous solution, the scrubbing process is still required, and thus the productivity is high. bad. In particular, if the coexisting impurity is zirconium, it cannot be sufficiently separated by scrubbing, and it is necessary to remove the zirconium from the scandium-containing aqueous solution in advance using tenoyltrifluoroacetone as an extractant. , Productivity further decreases.
　また、上記非特許文献１では、スカンジウム原料として硝酸スカンジウムを用い、硝酸スカンジウムと、硝酸ナトリウム及び硝酸とを混合して、カルボン酸系抽出剤を用いることが開示されている。硝酸スカンジウムは水溶性であるので、スカンジウムは、硝酸ナトリウム及び硝酸に溶解する。しかし、難溶性のスカンジウム原料は、硝酸ナトリウム及び硝酸には溶解しにくい。このため、スカンジウム原料として難溶性の材料を用いた場合、難溶性のスカンジウム原料と、硝酸ナトリウム及び硝酸とを混合しても、スカンジウムの溶出量は少ない。したがって、カルボン酸系抽出剤を用いても、抽出可能なスカンジウム量がそもそも少ないので、生産性が悪いという問題がある。 In addition, Non-Patent Document 1 discloses that scandium nitrate is used as a scandium raw material, scandium nitrate is mixed with sodium nitrate and nitric acid, and a carboxylic acid-based extractant is used. Since scandium nitrate is water soluble, scandium dissolves in sodium nitrate and nitric acid. However, the hardly soluble scandium raw material is difficult to dissolve in sodium nitrate and nitric acid. For this reason, when a hardly soluble material is used as the scandium raw material, even if the poorly soluble scandium raw material is mixed with sodium nitrate and nitric acid, the amount of scandium eluted is small. Therefore, even if a carboxylic acid-based extractant is used, the amount of scandium that can be extracted is small in the first place, and there is a problem that productivity is poor.
　本発明は、上記問題点に鑑み、生産性を向上するスカンジウムの分離方法を提供することを課題とする。 In view of the above problems, an object of the present invention is to provide a scandium separation method that improves productivity.
　本発明者らは、スカンジウム原料が難溶性であっても、生産性を向上できるスカンジウムの分離方法を鋭意研究した結果、ｐＨ４未満の酸性水溶液に溶解させると、スカンジウム原料の溶解量を増加することができると共に、これにアルカリを混合してｐＨを４以上７以下に調整した後に、カルボン酸系抽出剤を含む有機溶媒と接触させて溶媒抽出を行うと、不純物の有機溶媒への抽出量を低く抑えることができ、スカンジウムを主に抽出することができることを見出して、本発明を完成させた。 As a result of intensive research on a method for separating scandium that can improve productivity even if the scandium raw material is poorly soluble, the amount of the scandium raw material increased when dissolved in an acidic aqueous solution having a pH of less than 4. In addition, after adjusting the pH to 4 or more and 7 or less by mixing with an alkali, and performing contact with an organic solvent containing a carboxylic acid-based extractant, the amount of impurities extracted into the organic solvent is reduced. The present invention was completed by finding that it can be kept low and that scandium can be mainly extracted.
　すなわち、本発明の一の局面におけるスカンジウムの分離方法は、スカンジウムを含有し、ｐＨが４未満の酸性水溶原液を準備する工程と、酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整することにより、第１酸性水溶液を生成する工程と、第１酸性水溶液と、カルボン酸及び／またはカルボン酸塩を抽出剤として含む有機溶媒とを接触させて、第１酸性水溶液中のスカンジウムを有機溶媒に移動することにより、スカンジウム含有有機溶媒を生成する工程と、スカンジウム含有有機溶媒と、第２酸性水溶液とを接触させて、スカンジウム含有有機溶媒中のスカンジウムを第２酸性水溶液に移動することにより、スカンジウム含有水溶液を生成する工程とを備えている。 That is, the method for separating scandium according to one aspect of the present invention comprises a step of preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4; By adjusting to the following ranges, the first acidic aqueous solution is brought into contact with the first acidic aqueous solution and an organic solvent containing a carboxylic acid and / or a carboxylate as an extractant. The scandium in the scandium-containing organic solvent is brought into contact by bringing the scandium-containing organic solvent into contact with the second acidic aqueous solution by transferring the scandium in the organic solvent to the scandium-containing organic solvent. To generate a scandium-containing aqueous solution.
　本発明の一の局面におけるスカンジウムの分離方法において好ましくは、スカンジウム含有水溶液と、析出剤とを接触させて、スカンジウム化合物を析出する工程をさらに備えている。 Preferably, the method for separating scandium according to one aspect of the present invention further includes a step of bringing a scandium-containing aqueous solution into contact with a precipitation agent to precipitate a scandium compound.
　また、本発明の他の局面におけるスカンジウムの分離方法は、スカンジウムを含有し、ｐＨが４未満の酸性水溶原液を準備する工程と、酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整することにより、第１酸性水溶液を生成する工程と、第１酸性水溶液と、カルボン酸及び／またはカルボン酸塩を抽出剤として含む有機溶媒とを接触させて、第１酸性水溶液中のスカンジウムを有機溶媒に移動することにより、スカンジウム含有有機溶媒を生成する工程と、スカンジウム含有有機溶媒と、析出剤とを接触させて、スカンジウム化合物を生成する工程とを備えている。 Further, the method for separating scandium according to another aspect of the present invention includes a step of preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4, and an acidic aqueous stock solution and an alkali, so that the pH is 4 or more and 7 By adjusting to the following ranges, the first acidic aqueous solution is brought into contact with the first acidic aqueous solution and an organic solvent containing a carboxylic acid and / or a carboxylate as an extractant. The method includes a step of generating a scandium-containing organic solvent by moving scandium therein to an organic solvent, and a step of bringing a scandium-containing organic solvent into contact with a precipitation agent to generate a scandium compound.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、析出剤は、カルボン酸及び／またはカルボン酸塩である。 In the method for separating scandium in one aspect and another aspect of the present invention, preferably, the precipitating agent is a carboxylic acid and / or a carboxylate.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、スカンジウム化合物を乾燥及び／または焼成する工程をさらに備えている。 Preferably, the method for separating scandium according to one aspect and the other aspect of the present invention further includes a step of drying and / or firing the scandium compound.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、抽出剤は、ナフテン酸及び／またはネオデカン酸である。 In the method for separating scandium in one aspect and another aspect of the present invention, preferably, the extractant is naphthenic acid and / or neodecanoic acid.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、有機溶媒は、改質剤をさらに含む。 In the scandium separation method according to one aspect and another aspect of the present invention, the organic solvent preferably further includes a modifier.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、改質剤は、リン酸トリブチルである。 In the method for separating scandium according to one aspect and another aspect of the present invention, preferably, the modifier is tributyl phosphate.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、酸性水溶原液は、チタン、ジルコニウム、バナジウム及びスカンジウム以外の希土類元素から選ばれる少なくとも一種の金属イオンをさらに含む。 Preferably, in the scandium separation method according to one aspect and the other aspect of the present invention, the acidic aqueous solution further contains at least one metal ion selected from rare earth elements other than titanium, zirconium, vanadium, and scandium.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、酸性水溶原液は、鉱石及び／または鉱石の残滓を酸で溶解した水溶液である。 In the scandium separation method according to one aspect and the other aspect of the present invention, the acidic aqueous stock solution is preferably an aqueous solution in which ore and / or residue of the ore are dissolved with an acid.
　本発明の一の局面及び他の局面におけるスカンジウムの分離方法において好ましくは、酸性水溶原液は、スカンジウムを含む水性スラリーと酸とを混合して、ｐＨを２以下に調整した水溶液である。 In the method for separating scandium according to one aspect and the other aspect of the present invention, preferably, the acidic aqueous stock solution is an aqueous solution in which an aqueous slurry containing scandium and an acid are mixed to adjust the pH to 2 or less.
　本発明のスカンジウムの分離方法によれば、ｐＨが４未満の酸性水溶原液を準備することにより、スカンジウム原料の溶出量を増加することができ、酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整した後に、カルボン酸及び／またはカルボン酸塩を抽出剤として含む有機溶媒とを接触させることにより、スカンジウムを有機溶媒に移動させて、有機溶媒中の不純物を低減させることができる。したがって、本発明は、生産性を向上するスカンジウムの分離方法を提供することができる。 According to the scandium separation method of the present invention, by preparing an acidic aqueous stock solution having a pH of less than 4, the amount of elution of the scandium raw material can be increased, and the acidic aqueous stock solution and alkali are mixed to adjust the pH. After adjusting to the range of 4 or more and 7 or less, by contacting with an organic solvent containing carboxylic acid and / or carboxylate as an extractant, scandium is transferred to the organic solvent to reduce impurities in the organic solvent. be able to. Therefore, the present invention can provide a scandium separation method that improves productivity.
本発明の実施の形態１のスカンジウムの分離方法を示すフローチャートである。It is a flowchart which shows the separation method of the scandium of Embodiment 1 of this invention. 本発明の実施の形態１のスカンジウムの分離方法における各工程での模式図である。It is the schematic diagram in each process in the separation method of scandium of Embodiment 1 of this invention. 本発明の実施の形態２スカンジウムの分離方法を示すフローチャートである。Embodiment 2 of the present invention is a flowchart showing a method for separating scandium. 本発明の実施の形態２のスカンジウムの分離方法における各工程での模式図である。It is the schematic diagram in each process in the separation method of scandium of Embodiment 2 of this invention.
　以下、図面に基づいて本発明の実施の形態を説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
　（実施の形態１）
　図１及び図２を参照して、本発明の実施形態１のスカンジウムの分離方法について説明する。 (Embodiment 1)
With reference to FIG.1 and FIG.2, the separation method of the scandium of Embodiment 1 of this invention is demonstrated.
　（準備工程）
　まず、図１及び図２に示すように、スカンジウムを含有し、ｐＨが４未満の酸性水溶原液を準備する（ステップＳ１：準備工程）。酸性水溶原液は、スカンジウムを含有していれば特に限定されず、例えばスカンジウムイオンを含む酸性水溶液、水酸化スカンジウム、酸化スカンジウムを含むスラリー等のスカンジウムを含む酸性水溶液等である。また、酸性水溶原液のｐＨは４未満であり、品質の安定性の観点から３以下が好ましく、２以下がさらに好ましく、１以下がさらに一層好ましい。酸性水溶原液中において、スカンジウムはイオンとして安定的に存在する。 (Preparation process)
First, as shown in FIGS. 1 and 2, an acidic aqueous stock solution containing scandium and having a pH of less than 4 is prepared (step S1: preparation step). The acidic aqueous stock solution is not particularly limited as long as it contains scandium, and examples thereof include an acidic aqueous solution containing scandium ions, an acidic aqueous solution containing scandium such as a slurry containing scandium hydroxide and scandium oxide, and the like. Further, the pH of the acidic aqueous stock solution is less than 4, preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less from the viewpoint of quality stability. In the acidic aqueous stock solution, scandium stably exists as ions.
　酸性水溶原液には、スカンジウムのほかに、スカンジウム以外の希土類元素（イットリウム、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、ユウロピウム、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）を含んでいてもよく、チタン、バナジウム、クロム、マンガン、鉄、コバルト、ニッケル、銅、ジルコニウム、ニオブ、モリブデン、テクネチウム、ルテニウム、ロジウム、パラジウム、銀等の遷移金属元素を含んでいてもよく、トリウム、ウラン等の放射性元素を含んでいてもよく、そのほかのアルカリ金属元素、アルカリ土類金属元素、亜鉛、カドミウム等の周期表第１２族元素、ホウ素、アルミニウム、ガリウム、インジウム等の周期表第１３族元素、ケイ素、ゲルマニウム、スズ等の周期表第１４族元素、リン、ヒ素、アンチモン、ビスマス等の周期表第１５族元素、セレン、テルル等の周期表第１６族元素、フッ素、塩素等の周期表第１７族元素等の典型元素を含んでいてもよい。スカンジウムのほかにチタン、ジルコニウム、バナジウム及びスカンジウム以外の希土類元素から選ばれる少なくとも一種の金属イオンを含む酸性水溶原液は、効果が得られやすいため好適に用いられる。 In addition to scandium, the acidic aqueous stock solution contains rare earth elements other than scandium (yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). May contain, transition metal elements such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, thorium May contain radioactive elements such as uranium, other alkali metal elements, alkaline earth metal elements, group 12 elements of the periodic table such as zinc and cadmium, boron, aluminum, gallium, indium, etc. Periodic group 13 element, periodic table group 14 element such as silicon, germanium, tin, periodic table group 15 element such as phosphorus, arsenic, antimony, bismuth, periodic table group 16 element such as selenium, tellurium, fluorine In addition, a typical element such as a group 17 element of the periodic table such as chlorine may be included. In addition to scandium, an acidic aqueous stock solution containing at least one metal ion selected from titanium, zirconium, vanadium, and a rare earth element other than scandium is preferably used because the effect is easily obtained.
　酸性水溶原液中のスカンジウムの濃度には特段の制限はなく、収量の関係では高いものが好ましく、５００～５００００ｍｇ／Ｌ程度がより好ましい。なお、スカンジウム濃度は低くてもよく、例えば１０～５００ｍｇ／Ｌ程度でも本実施の形態の分離方法においてスカンジウムを分離することができる。 The concentration of scandium in the acidic aqueous stock solution is not particularly limited, and is preferably high in terms of yield, more preferably about 500 to 50,000 mg / L. The scandium concentration may be low. For example, scandium can be separated by the separation method of the present embodiment even at about 10 to 500 mg / L.
　酸性水溶原液中のスカンジウム以外の元素（不純物）の濃度にも特段の制限はないが、スカンジウムの分離をしやすくするためには不純物成分が少なく、その濃度が低いものが好ましい。酸性水溶原液がチタン、ジルコニウム及びバナジウムを含んでいる場合には、それぞれ１０００ｍｇ／Ｌ以下程度がより好ましく、０ｍｇ／Ｌであることがより一層好ましい。さらに、酸性水溶原液がスカンジウム以外の希土類元素を含んでいる場合には、それぞれ１０００ｍｇ／Ｌ以下程度がより好ましく、０ｍｇ／Ｌであることがより一層好ましい。 There is no particular limitation on the concentration of elements (impurities) other than scandium in the acidic aqueous stock solution, but in order to facilitate the separation of scandium, there are few impurity components and those with low concentrations are preferred. When the acidic aqueous stock solution contains titanium, zirconium and vanadium, each is preferably about 1000 mg / L or less, and more preferably 0 mg / L. Furthermore, when the acidic aqueous solution contains a rare earth element other than scandium, it is more preferably about 1000 mg / L or less, and even more preferably 0 mg / L.
　酸性水溶原液は、スカンジウムを含む酸性水溶液を用いたり、その溶液を粗精製処理した酸性水溶液を用いたり、水酸化スカンジウム、酸化スカンジウム等を含むスラリーに酸を混合して酸性水溶液を調製することにより準備できる。酸性水溶原液として、例えば、次のような酸性水溶液を用いることができ、スカンジウムを多く含む観点から、鉱石を酸で溶解した水溶液及び／または鉱石の残滓を酸で溶解した水溶液が好ましく、スカンジウムを含む水性スラリーと酸とを混合して、ｐＨを２以下に調整した水溶液がより好ましい。
（１）スカンジウムを含む鉱石等の材料を酸で溶解した酸性水溶液
（２）スカンジウムを含む鉱石等の材料を酸で溶解した液を加水分解または中和して他の金属成分を精製した後の酸性水溶液、あるいは他の金属成分を精製した後の残滓を酸で溶解した酸性水溶液
（３）スカンジウムを含む鉱石等の材料を予めアルカリで溶解することにより不純物を低減した後に、不純物を低減した材料に酸を混合した酸性水溶液
（４）上記（１）～（３）の酸性水溶液に含まれるスカンジウムをイオン交換樹脂で吸着溶離したり、沈殿分離するなどしてスカンジウムを粗精製した後の酸性水溶液
（５）上記（１）～（３）の酸性水溶液に含まれるスカンジウムをイオン交換樹脂で吸着溶離したり、沈殿分離するなどしてスカンジウムを粗精製した水酸化スカンジウム、酸化スカンジウム等を含むスラリーに酸を混合して得られた酸性水溶液
　スカンジウムを含む材料としては、水溶性であってもよく、難溶性（不溶性を含む）であってもよく、例えば、種々の鉱石、鉱石から他の金属成分を精錬した後の残滓の他に、スカンジウムを含むアルミニウム合金、ニッケル・アルカリ蓄電池の陽極、メタルハライドランプ、固体酸化物燃料電池の電解質、スカンジア安定化ジルコニア等のセラミックス等の各種材料や廃棄物を使用することができる。 The acidic aqueous stock solution is prepared by using an acidic aqueous solution containing scandium, using an acidic aqueous solution obtained by roughly purifying the solution, or preparing an acidic aqueous solution by mixing an acid with a slurry containing scandium hydroxide, scandium oxide, or the like. Ready. As the acidic aqueous stock solution, for example, the following acidic aqueous solution can be used. From the viewpoint of containing a large amount of scandium, an aqueous solution obtained by dissolving ore with an acid and / or an aqueous solution obtained by dissolving an ore residue with an acid is preferable. An aqueous solution prepared by mixing the aqueous slurry containing the acid and adjusting the pH to 2 or less is more preferable.
(1) Acidic aqueous solution in which materials such as ores containing scandium are dissolved with acid (2) After refining other metal components by hydrolyzing or neutralizing a solution in which materials such as ores containing scandium are dissolved in acids Acidic aqueous solution or acidic aqueous solution in which the residue after refining other metal components is dissolved with acid (3) After reducing impurities by dissolving materials such as ores containing scandium with alkali in advance, the material with reduced impurities (4) Acidic aqueous solution obtained by roughly purifying scandium by adsorbing and eluting the scandium contained in the acidic aqueous solutions (1) to (3) above with an ion exchange resin or by separating the precipitates by precipitation. (5) The scandium contained in the acidic aqueous solution of (1) to (3) above is adsorbed and eluted with an ion exchange resin, or precipitated and separated. Acidic aqueous solution obtained by mixing acid with slurry containing indium, scandium oxide, etc. The material containing scandium may be water-soluble or sparingly soluble (including insoluble). Ores, other residues after refining other metal components from ores, aluminum alloys containing scandium, anodes of nickel / alkaline batteries, metal halide lamps, solid oxide fuel cell electrolytes, scandia stabilized zirconia ceramics, etc. Various materials and wastes such as can be used.
　鉱石としては、例えば、トルトベイト石、金鉱石、銀鉱石、銅鉱石、鉛鉱石、ビスマス鉱石、スズ鉱石、アンチモン鉱石、水銀鉱石、亜鉛鉱石、鉄鉱石、クロム鉱石、マンガン鉱石、タングステン鉱石、モリブデン鉱石、ヒ素鉱石、ニッケル鉱石、コバルト鉱石、ウラン鉱石、トリウム鉱石、リン鉱石、硫黄鉱石、バリウム鉱石、カルシウム鉱石、マグネシウム鉱石、ストロンチウム鉱石、ベリリウム鉱石、アルミニウム鉱石、チタン鉱石等が挙げられ、鉄鉱石、ニッケル鉱石、チタン鉱石、マンガン鉱石、スズ鉱石、アルミニウム鉱石等のスカンジウムを多く含んでいる鉱石が好ましい。 As ores, for example, tortue bait, gold ore, silver ore, copper ore, lead ore, bismuth ore, tin ore, antimony ore, mercury ore, zinc ore, iron ore, chromium ore, manganese ore, tungsten ore, molybdenum ore Arsenic ore, nickel ore, cobalt ore, uranium ore, thorium ore, phosphorus ore, sulfur ore, barium ore, calcium ore, magnesium ore, strontium ore, beryllium ore, aluminum ore, titanium ore etc., iron ore, Ores containing a large amount of scandium such as nickel ore, titanium ore, manganese ore, tin ore and aluminum ore are preferred.
　鉱石等の材料を溶解する酸あるいは酸性に調整する酸は、制限なく用いることができ、塩酸、硫酸、硝酸、フッ酸、王水等の無機酸や酢酸等の有機酸を用いることができる。また、鉱石等の材料を酸で溶解した液を加水分解したり中和したりして他の金属成分を精錬した後の液を、鉱石等の材料を溶解する酸あるいは酸性に調整する酸として用いることもできる。このような他の金属成分を精錬した後の液として、例えば、ラテライト鉱のニッケル酸化鉱に硫酸を添加して加圧浸出することによって得られる浸出液、その浸出液からニッケル成分を取り出した後の液を用いることができる。また、ルチル鉱、チタン鉄鉱等のチタン鉱石や鉄鉱石に硫酸、塩酸、硝酸、フッ酸、王水等の無機酸、酢酸等の有機酸の酸で溶解した溶解液、その溶解液を加水分解、中和してチタン成分、鉄成分を取り出した後の液等を、鉱石等の材料を溶解する酸あるいは酸性に調整する酸として用いることができる。また、鉱石中の他の金属を塩素化し気体として取り出した後の残滓を酸で溶解した液を、鉱石等の材料を溶解する酸あるいは酸性に調整する酸として用いることができ、例えば、ルチル鉱、チタン鉄鉱等のチタン鉱石や鉄鉱石を塩素ガスで塩素化し塩化チタン、塩化鉄を取り出した後の残滓を硫酸、塩酸、硝酸、フッ酸、王水等の無機酸、酢酸等の有機酸の酸で溶解した溶解液、その溶解液を加水分解してチタン成分、鉄成分を取り出した後の液等を用いることができる。 An acid that dissolves a material such as ore or an acid that is adjusted to be acidic can be used without limitation, and inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, and aqua regia, and organic acids such as acetic acid can be used. In addition, the liquid after refining other metal components by hydrolyzing or neutralizing the liquid in which the material such as ore is dissolved with an acid is used as the acid that dissolves the material such as ore or the acid that is adjusted to be acidic. It can also be used. As a liquid after refining such other metal components, for example, a leachate obtained by adding sulfuric acid to a nickel oxide ore of laterite ore and leaching under pressure, a liquid after taking out the nickel component from the leachate Can be used. In addition, a solution in which titanium ore such as rutile or titanite or iron ore is dissolved with an acid such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, or aqua regia, or an organic acid such as acetic acid, and the solution is hydrolyzed. The liquid after neutralizing and taking out the titanium component and the iron component can be used as an acid for dissolving materials such as ore or an acid for adjusting the acidity. Moreover, the liquid which melt | dissolved the residue after chlorinating and extracting other metals in an ore with an acid can be used as an acid which dissolves materials, such as an ore, or an acid which adjusts to acidity, for example, a rutile ore Titanium ores such as iron ore and iron ore are chlorinated with chlorine gas, and the residue after taking out titanium chloride and iron chloride is made of inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, hydrofluoric acid, aqua regia, and organic acids such as acetic acid. A solution dissolved with an acid, a solution obtained by hydrolyzing the solution and taking out a titanium component and an iron component, and the like can be used.
　一方、鉱石等の材料をアルカリで溶解する場合は、スカンジウムはアルカリには溶解し難く、ほとんどが固体成分として残るため、そのアルカリ性溶解液、または、そのアルカリ性溶解液を加水分解や中和して他の金属を取り出した後のアルカリ性液等から、スカンジウムを含む固体成分を分離し、当該固体成分に酸を混合してｐＨを酸性にして酸性水溶原液とすることができる。鉱石等の材料を溶解するアルカリは、制限なく用いることができ、例えば、水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物、水酸化カルシウム等のアルカリ土類金属水酸化物、アンモニア、アミン類等を用いることができる。鉱石等の材料をアルカリで溶解した後にｐＨを酸性に調整する酸は、制限なく用いることができ、塩酸、硫酸、硝酸、フッ酸、王水等の無機酸や酢酸等の有機酸を用いることができ、上記の鉱石等の材料を溶解した酸性水溶液を用いてもよい。 On the other hand, when materials such as ores are dissolved in alkali, scandium is difficult to dissolve in alkali, and most remains as a solid component. Therefore, the alkaline solution or the alkaline solution is hydrolyzed or neutralized. A solid component containing scandium can be separated from an alkaline solution or the like after taking out another metal, and an acid can be mixed with the solid component to make the pH acidic to obtain an acidic aqueous stock solution. Alkalis that dissolve materials such as ores can be used without limitation, for example, alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, ammonia, amines Etc. can be used. Acids that adjust the pH to acidic after dissolving materials such as ores with alkali can be used without limitation, and use inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, aqua regia, and organic acids such as acetic acid. An acidic aqueous solution in which materials such as the above ores are dissolved may be used.
　スカンジウムの粗精製は、上述した酸性水溶液を用いて、それに含まれるスカンジウムを従来の方法で、例えば、イオン交換樹脂で吸着し、次いで、イオン交換樹脂から溶離によって、あるいは、ｐＨ調整などして沈殿分離処理して得られた水酸化スカンジウム、酸化スカンジウム等を水に分散するなどして、スカンジウムの濃度を高めることができる。このように粗精製した液と酸とを加えて４未満にｐＨ調整した溶液も酸性水溶原液として用いることができる。 For the rough purification of scandium, the above-mentioned acidic aqueous solution is used to adsorb the scandium contained in the conventional method, for example, with an ion exchange resin, and then precipitate by elution from the ion exchange resin or pH adjustment. The concentration of scandium can be increased by dispersing scandium hydroxide, scandium oxide, or the like obtained by the separation treatment in water. A solution whose pH is adjusted to less than 4 by adding the roughly purified solution and the acid can also be used as the acidic aqueous stock solution.
　（ｐＨ調整工程）
　次に、図１及び図２に示すように、酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整することにより、第１酸性水溶液を生成する（ステップＳ２：ｐＨ調整工程）。この工程（ステップＳ２）を実施することで得られる第１酸性水溶液は、図２に示すように、水酸化物として存在するＳｃ（ＯＨ）3及びイオンとして存在するＳｃ3+と、酸性水溶原液からの不純物とを含む。 (PH adjustment step)
Next, as shown in FIGS. 1 and 2, the acidic aqueous undiluted solution and the alkali are mixed, and the first acidic aqueous solution is generated by adjusting the pH to the range of 4 or more and 7 or less (Step S2: pH). Adjustment process). As shown in FIG. 2, the first acidic aqueous solution obtained by carrying out this step (step S2) is composed of Sc (OH) 3 present as hydroxide, Sc 3+ present as ions, and an acidic aqueous stock solution. And impurities from.
　この工程（ステップＳ２）においてｐＨを４以上７以下にすることによって、後述する有機溶媒抽出工程（ステップＳ３）においてスカンジウムが主に抽出されると共に、不純物の抽出を低減できる。ｐＨが４未満であると、スカンジウムの抽出量が大幅に減少し、分離できるスカンジウムの収率が低下する。ｐＨが７より高いと、後述する有機溶媒抽出工程（ステップＳ３）において不純物の抽出量が増加し、スカンジウムの分離効率が低下する。この観点から、ｐＨを５以上７以下の範囲に調整することが好ましく、詳細には、ｐＨを５．０以上６．５以下の範囲に調整することが好ましく、６．０以上６．５以下の範囲に調整することがさらに好ましい。 In this step (step S2), by setting the pH to 4 or more and 7 or less, scandium is mainly extracted in the organic solvent extraction step (step S3) described later, and impurity extraction can be reduced. If the pH is less than 4, the amount of scandium extracted is greatly reduced, and the yield of separable scandium is reduced. If the pH is higher than 7, the amount of extracted impurities increases in the organic solvent extraction step (step S3) described later, and the scandium separation efficiency decreases. From this viewpoint, it is preferable to adjust the pH to a range of 5 or more and 7 or less. Specifically, it is preferable to adjust the pH to a range of 5.0 or more and 6.5 or less, and 6.0 or more and 6.5 or less. It is more preferable to adjust to this range.
　ｐＨを調整するためのアルカリとしては、アルカリ性を呈するものであれば制限なく用いることができ、固体であっても液体であってもよい。このようなアルカリは、例えば水酸化ナトリウム、水酸化カリウム等のアルカリ金属水酸化物、水酸化カルシウム、水酸化マグネシウム、水酸化バリウム等のアルカリ土類金属水酸化物、アンモニア、アミン類等を用いることができる。 The alkali for adjusting the pH can be used without limitation as long as it exhibits alkalinity, and may be solid or liquid. Examples of such alkalis include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, alkaline earth metal hydroxides such as calcium hydroxide, magnesium hydroxide and barium hydroxide, ammonia and amines. be able to.
　（有機溶媒抽出工程）
　次に、図１及び図２に示すように、第１酸性水溶液と、カルボン酸及び／またはカルボン酸塩（以下、カルボン酸系抽出剤とも言う）を抽出剤として含む有機溶媒とを接触させて、第１酸性水溶液中のスカンジウムを有機溶媒に移動することにより、スカンジウム含有有機溶媒を生成する（ステップＳ３：有機溶媒抽出工程）。具体的には、このステップＳ３では、カルボン酸及び／またはその塩を抽出剤として含む有機溶媒と、第１酸性水溶液とを混合して、スカンジウムと抽出剤とから形成される錯体を有機溶媒に抽出する。 (Organic solvent extraction process)
Next, as shown in FIGS. 1 and 2, the first acidic aqueous solution is brought into contact with an organic solvent containing a carboxylic acid and / or a carboxylic acid salt (hereinafter also referred to as a carboxylic acid-based extractant) as an extractant. Then, scandium in the first acidic aqueous solution is moved to the organic solvent to generate a scandium-containing organic solvent (step S3: organic solvent extraction step). Specifically, in this step S3, an organic solvent containing carboxylic acid and / or a salt thereof as an extractant is mixed with a first acidic aqueous solution, and a complex formed from scandium and the extractant is used as the organic solvent. Extract.
　ステップＳ３を実施することにより、スカンジウムを含有する有機溶媒（スカンジウム含有有機溶媒）と、スカンジウムを含有しなくなった第１酸性水溶液（抽出後の第１酸性水溶液）とが生成される。有機溶媒中のスカンジウムとカルボン酸系抽出剤とがカルボン酸スカンジウムの錯体を形成し、この錯体は有機溶媒に可溶であるので、錯体が有機溶媒に移動する。つまり、スカンジウム含有有機溶媒は、有機溶媒中の抽出剤と第１酸性水溶液中のスカンジウムイオンとにより生成されたカルボン酸スカンジウムと、不純物とを含有する。しかし、不純物の多くは抽出後の第１酸性水溶液中に残り、スカンジウム含有有機溶媒中に移動する不純物は、ｐＨ調整工程（ステップＳ２）における第１酸性水溶液中の不純物よりも少ない。 By performing Step S3, an organic solvent containing scandium (scandium-containing organic solvent) and a first acidic aqueous solution that no longer contains scandium (first acidic aqueous solution after extraction) are generated. Since the scandium in the organic solvent and the carboxylic acid-based extractant form a complex of scandium carboxylate, and this complex is soluble in the organic solvent, the complex moves to the organic solvent. In other words, the scandium-containing organic solvent contains scandium carboxylate produced by the extractant in the organic solvent and the scandium ions in the first acidic aqueous solution, and impurities. However, most of the impurities remain in the first acidic aqueous solution after extraction, and the impurities that move into the scandium-containing organic solvent are less than the impurities in the first acidic aqueous solution in the pH adjustment step (step S2).
　カルボン酸は、カルボキシ基を有する有機化合物であり、カルボン酸塩は、ナトリウム、カリウム、アンモニウム等の塩と、カルボン酸のカルボキシル基とが反応してなる。カルボン酸系抽出剤は、スカンジウムと錯体を形成するものであれば特に限定されず、例えば、ネオデカン酸（バーサティック酸系）、ナフテン酸系、オレイン酸系、ラウリン酸系等の公知の抽出剤を用いることができ、スカンジウムをより効果的に抽出できる観点から、ナフテン酸及び／またはネオデカン酸が好ましく用いられる。 Carboxylic acid is an organic compound having a carboxy group, and carboxylate is formed by reaction of a salt such as sodium, potassium or ammonium with the carboxyl group of carboxylic acid. The carboxylic acid-based extractant is not particularly limited as long as it forms a complex with scandium. For example, known extractants such as neodecanoic acid (versaic acid-based), naphthenic acid-based, oleic acid-based, and lauric acid-based extractants From the viewpoint that scandium can be extracted more effectively, naphthenic acid and / or neodecanoic acid is preferably used.
　カルボン酸系抽出剤の割合は適宜設定することができ、有機溶媒に対して１～５０質量％が好ましく、５～２０質量％がより好ましい。 The proportion of the carboxylic acid-based extractant can be appropriately set, and is preferably 1 to 50% by mass, more preferably 5 to 20% by mass with respect to the organic solvent.
　また、有機相（スカンジウム含有有機溶媒）と水相（抽出後の第１酸性水溶液）との界面に第三相が生成することを抑制するために、有機溶媒に改質剤を添加してもよい。改質剤としては、ノニルフェノール、１－デカノール、イソデカノール、１－オクタノール、２－エチルヘキサノール等の長鎖アルキル化合物や、リン酸トリブチル（ＴＢＰ）、トリオクチルホスフェート（ＴＯＰ）、トリオクチルホスフィンオキシド（ＴＯＰＯ）等のリン酸アルキル化合物、第１級アミン、第２級アミン、第３級アミン、第４級アンモニウム塩等のアミン類等が一例として挙げられる。第三相生成が抑制できるだけでなく、後述する逆抽出工程（ステップＳ４）でスカンジウムの回収率を向上することができるため、リン酸トリブチルが好ましく用いられる。改質剤の添加量は適宜設定することができ、有機溶媒に対して１～５０質量％が好ましく、５～４０質量％がより好ましい。 In addition, in order to suppress the formation of the third phase at the interface between the organic phase (scandium-containing organic solvent) and the aqueous phase (first acidic aqueous solution after extraction), a modifier may be added to the organic solvent. Good. Examples of the modifying agent include long-chain alkyl compounds such as nonylphenol, 1-decanol, isodecanol, 1-octanol, 2-ethylhexanol, tributyl phosphate (TBP), trioctyl phosphate (TOP), trioctylphosphine oxide (TOPO). Examples thereof include alkyl phosphate compounds such as), amines such as primary amines, secondary amines, tertiary amines, and quaternary ammonium salts. Since not only the third phase generation can be suppressed but also the back-extraction step (step S4) described later can improve the recovery rate of scandium, tributyl phosphate is preferably used. The addition amount of the modifier can be appropriately set and is preferably 1 to 50% by mass, more preferably 5 to 40% by mass with respect to the organic solvent.
　スカンジウムの溶媒抽出操作は、任意の液液接触装置を用いて、カルボン酸系抽出剤や必要に応じて改質剤を含む有機溶媒と酸性水溶原液とを適当な温度で一定時間、公知の手順で液液接触させ、次いで静置分離または遠心分離によって抽出剤相と水溶液相とに分離することにより行うことができる。液液接触装置としては、例えば遠心抽出機、ミキサー、振とう機、分液漏斗、多段式の液液接触装置、より具体的には向流多段のミキサーセトラー抽出装置が挙げられ、連続法及び回分法のいずれであってもよい。また、処理温度は、抽出操作前の酸性水溶原液及び抽出剤の温度を保持するように設定することが好ましいが、有機溶媒の引火点、相分離速度、抽出剤相の安定性などの点から、２０～７０℃に保つのが好ましい。溶媒抽出は１回に限ることはなく、数回に分けて行ってもよい。 The solvent extraction operation of scandium is carried out by using a known liquid-liquid contact apparatus, a carboxylic acid-based extractant and, if necessary, an organic solvent containing a modifier and an acidic aqueous undiluted solution at a suitable temperature for a certain period of time. By liquid-liquid contact, followed by separation into an extractant phase and an aqueous solution phase by stationary separation or centrifugation. Examples of the liquid-liquid contact device include a centrifugal extractor, a mixer, a shaker, a separatory funnel, a multistage liquid-liquid contact device, more specifically, a countercurrent multistage mixer-settler extractor, a continuous method and Any of batch methods may be used. Further, the treatment temperature is preferably set so as to maintain the temperature of the acidic aqueous undiluted solution and the extractant before the extraction operation, but from the viewpoint of the flash point of the organic solvent, the phase separation rate, the stability of the extractant phase, etc. The temperature is preferably maintained at 20 to 70 ° C. The solvent extraction is not limited to once, and may be performed in several steps.
　有機溶媒としては特に制限なく用いることができ、例えば、トルエン、ベンゼン、キシレン、エチルベンゼン、ジエチルベンゼン、イソプロピルベンゼン、アミルベンゼン、ジアミルベンゼン、アミルトルエン、クロロベンゼン、ブロモベンゼン、ｏ－ジクロロベンゼン、ｏ－クロロトルエン、ｐ－クロロトルエン等の芳香族系炭化水素化合物類；ケロシン、ｎ－ペンタン、ｎ－ヘキサン、イソヘキサン、ｎ－ヘプタン、イソヘプタン、ｎ－オクタン、イソオクタン、ｎ－デカン、ｎ－ドデカン、シクロヘキサン、クロロホルム、テトラクロロメタン、クロロエタン、１，１－ジクロロエタン、１，２－ジクロロエタン、１，１，１－トリクロロエタン、１，１，２－トリクロロエタン、２－クロロプロパン、１，２－ジクロロプロパン、１，２，３－トリクロロプロパン、１－クロロヘキサン、石油エーテル、石油ベンジン、リグロイン、ｎ－パラフィン等の脂肪族系炭化水素化合物類；アイソパー（エクソン　モービル　コーポレーション社の登録商標）、ソルベッソ（エクソン　モービル　コーポレーション社の登録商標）、エクソール（エクソン　モービル　コーポレーション社の登録商標）等の工業用希釈剤などが一例として挙げられる。また、これらの有機溶媒は１種または２種以上を混合して使用してもよい。 The organic solvent can be used without any particular limitation. For example, toluene, benzene, xylene, ethylbenzene, diethylbenzene, isopropylbenzene, amylbenzene, diamylbenzene, amyltoluene, chlorobenzene, bromobenzene, o-dichlorobenzene, o-chloro Aromatic hydrocarbon compounds such as toluene and p-chlorotoluene; kerosene, n-pentane, n-hexane, isohexane, n-heptane, isoheptane, n-octane, isooctane, n-decane, n-dodecane, cyclohexane, Chloroform, tetrachloromethane, chloroethane, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, 1,1,2-trichloroethane, 2-chloropropane, 1,2-dichloropropane, Aliphatic hydrocarbon compounds such as 1,2,3-trichloropropane, 1-chlorohexane, petroleum ether, petroleum benzine, ligroin, n-paraffin; Isopar (registered trademark of Exxon Mobil Corporation), Solvesso (Exxon Mobil Corporation) Industrial diluents such as Exxor (registered trademark of Exxon Mobil Corporation), etc. are examples. Moreover, you may use these organic solvents 1 type or in mixture of 2 or more types.
　（逆抽出工程）
　次に、図１及び図２に示すように、スカンジウム含有有機溶媒と、第２酸性水溶液とを接触させて、スカンジウム含有有機溶媒中のスカンジウムを第２酸性水溶液に移動することにより、スカンジウム含有水溶液を生成する（ステップＳ４：逆抽出工程）。具体的には、このステップＳ４では、有機溶媒抽出工程（ステップＳ３）で抽出したスカンジウムを含む有機溶媒（スカンジウム含有溶媒）と第２酸性水溶液とを混合して、スカンジウムを第２酸性水溶液に逆抽出して精製と濃縮とを行う。ステップＳ４を実施することにより、スカンジウムを含有する第２酸性水溶液（スカンジウム含有水溶液）と、スカンジウムを含有しなくなった有機溶媒（逆抽出後の有機溶媒）とが生成される。スカンジウム含有水溶液は、第２酸性水溶液によってスカンジウム含有有機溶媒中のスカンジウムから生成されるスカンジウムイオンと、スカンジウム含有有機溶媒中の一部の不純物とを含有する。このスカンジウム含有水溶液中の不純物は、有機溶媒抽出工程（ステップＳ３）のスカンジウム含有有機溶媒中の不純物よりも少ない、または同程度である。つまり、スカンジウム含有水溶液中の不純物は、準備工程（ステップＳ１）における酸性水溶原液及びｐＨ調整工程（ステップＳ２）における第１酸性水溶液中の不純物よりも少ない。 (Back extraction process)
Next, as shown in FIG. 1 and FIG. 2, the scandium-containing organic solvent and the second acidic aqueous solution are brought into contact with each other, and the scandium in the scandium-containing organic solvent is moved to the second acidic aqueous solution. (Step S4: back extraction step). Specifically, in step S4, an organic solvent containing scandium (scandium-containing solvent) extracted in the organic solvent extraction step (step S3) and the second acidic aqueous solution are mixed, and the scandium is converted into the second acidic aqueous solution. Extract and purify and concentrate. By performing step S4, the 2nd acidic aqueous solution (scandium containing aqueous solution) containing scandium and the organic solvent (organic solvent after back extraction) which no longer contains scandium are produced | generated. The scandium-containing aqueous solution contains scandium ions generated from scandium in the scandium-containing organic solvent by the second acidic aqueous solution and some impurities in the scandium-containing organic solvent. Impurities in the scandium-containing aqueous solution are less than or comparable to those in the scandium-containing organic solvent in the organic solvent extraction step (step S3). That is, the impurities in the scandium-containing aqueous solution are less than the impurities in the acidic aqueous stock solution in the preparation step (step S1) and the first acidic aqueous solution in the pH adjustment step (step S2).
　第２酸性水溶液は、塩酸、硫酸、硝酸等の無機酸、酢酸等の有機酸を用いることができる。スカンジウムの逆抽出操作は、液液接触装置を用いて、有機溶媒と第２酸性水溶液とを適当な温度で一定時間、公知の手順で液液接触させ、次いで静置分離または遠心分離によって水溶液相（スカンジウム含有水溶液）と有機相（逆抽出後の有機溶媒）とに分離することにより行うことができる。液液接触装置としては、例えば遠心抽出機、ミキサー、振とう機、分液漏斗、多段式の液液接触装置、より具体的には向流多段のミキサーセトラー抽出装置や遠心抽出機が挙げられ、連続法及び回分法のいずれであってもよい。逆抽出は１回に限ることはなく、数回に分けて行ってもよい。また、有機溶媒抽出工程（ステップＳ３）及び逆抽出工程（ステップＳ４）は１回に限ることはなく、数回繰り返することによりスカンジウムの濃度を高めることができるため好ましい。このようにして、有機溶媒抽出工程（ステップＳ３）及び逆抽出工程（ステップＳ４）を行うと、スカンジウムの純度は例えば９９.０質量％以上となり、好ましくは９９．５質量％以上とすることができる。 As the second acidic aqueous solution, an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid, or an organic acid such as acetic acid can be used. The scandium back-extraction operation uses a liquid-liquid contact device to bring the organic solvent and the second acidic aqueous solution into contact with each other at a suitable temperature for a certain period of time using a known procedure, and then to the aqueous phase by stationary separation or centrifugation. It can be performed by separating into (scandium-containing aqueous solution) and an organic phase (an organic solvent after back extraction). Examples of the liquid-liquid contact apparatus include a centrifugal extractor, a mixer, a shaker, a separatory funnel, a multistage liquid-liquid contact apparatus, and more specifically, a countercurrent multistage mixer-settler extractor and a centrifugal extractor. Any of a continuous method and a batch method may be used. The back extraction is not limited to once, and may be performed in several steps. In addition, the organic solvent extraction step (step S3) and the back extraction step (step S4) are not limited to once, and it is preferable because the concentration of scandium can be increased by repeating several times. Thus, when the organic solvent extraction step (step S3) and the back extraction step (step S4) are performed, the purity of scandium is, for example, 99.0% by mass or more, and preferably 99.5% by mass or more. it can.
　（析出工程）
　次に、図１及び図２に示すように、スカンジウム含有水溶液と、析出剤とを接触させて、スカンジウム化合物を析出する（ステップＳ５：析出工程）。具体的には、逆抽出工程（ステップＳ４）において逆抽出したスカンジウム含有水溶液と析出剤を含有する水溶液とを混合することによりスカンジウムを析出させ、スカンジウムを沈殿物として回収する。このステップＳ５を実施することにより、スカンジウム含有水溶液中のスカンジウムと析出剤とが反応して、沈殿物としてのスカンジウム化合物が生成される。混合溶液中には、スカンジウム含有水溶液中の不純物は維持されるが、スカンジウム含有水溶液中に含有される不純物は低減されているので、沈殿物中に含有される不純物を低減できる。なお、不純物は、基本的には混合溶液中にイオンとして存在する。 (Precipitation process)
Next, as shown in FIG.1 and FIG.2, a scandium containing aqueous solution and a precipitation agent are made to contact, and a scandium compound is deposited (step S5: precipitation process). Specifically, scandium is precipitated by mixing the scandium-containing aqueous solution back-extracted in the back extraction step (step S4) and the aqueous solution containing the precipitation agent, and scandium is recovered as a precipitate. By performing this step S5, the scandium in the scandium-containing aqueous solution reacts with the precipitation agent, and a scandium compound as a precipitate is generated. Although the impurities in the scandium-containing aqueous solution are maintained in the mixed solution, the impurities contained in the scandium-containing aqueous solution are reduced, so that the impurities contained in the precipitate can be reduced. Impurities are basically present as ions in the mixed solution.
　析出剤は、スカンジウムを析出するものであれば特に限定されないが、スカンジウムの析出が容易である観点から、カルボン酸及び／またはカルボン酸塩（以下、カルボン酸系析出剤とも言う）であることが好ましい。また、スカンジウム含有水溶液と接触させる析出剤は、固体の状態で用いてもよく、析出剤を含む水溶液として用いてもよい。 The precipitating agent is not particularly limited as long as it precipitates scandium. From the viewpoint of easy precipitation of scandium, it may be a carboxylic acid and / or a carboxylate salt (hereinafter also referred to as a carboxylic acid-based precipitating agent). preferable. Moreover, the precipitation agent made to contact with a scandium containing aqueous solution may be used in a solid state, and may be used as an aqueous solution containing a precipitation agent.
　カルボン酸系析出剤として、例えば、ギ酸（メタン酸）、酢酸（エタン酸）、プロピオン酸（プロパン酸）、酪酸（ブタン酸）、吉草酸（ペンタン酸）、カプロン酸（ヘキサン酸）、エナント酸（ヘプタン酸）、カプリル酸（オクタン酸）等の脂肪酸、乳酸（２－ヒドロキシプロパン酸）、リンゴ酸（２－ヒドロキシブタン二酸）、クエン酸（２－ヒドロキシプロパントリカルボン酸）等のヒドロキシ酸、シュウ酸（エタン二酸）、マロン酸（プロパン二酸）、コハク酸（ブタン二酸）グルタル酸（ペンタン二酸）、アジピン酸（ヘキサン二酸）、フマル酸（（Ｅ）－ブタ－２－エン二酸）、マレイン酸（（Ｚ）－ブタ－２－エン二酸）等のジカルボン酸等やそれらの塩を用いることができ、シュウ酸等のジカルボン酸及び／またはその塩が好ましい。 Examples of carboxylic acid-based precipitants include formic acid (methanoic acid), acetic acid (ethanoic acid), propionic acid (propanoic acid), butyric acid (butanoic acid), valeric acid (pentanoic acid), caproic acid (hexanoic acid), and enanthic acid (Heptanoic acid), fatty acids such as caprylic acid (octanoic acid), hydroxy acids such as lactic acid (2-hydroxypropanoic acid), malic acid (2-hydroxybutanedioic acid), citric acid (2-hydroxypropanetricarboxylic acid), Oxalic acid (ethanedioic acid), malonic acid (propanedioic acid), succinic acid (butanedioic acid) glutaric acid (pentanedioic acid), adipic acid (hexanedioic acid), fumaric acid ((E) -but-2- Dicarboxylic acids such as enedioic acid) and maleic acid ((Z) -but-2-enedioic acid) and their salts, and dicarboxylic acids such as oxalic acid and / or their salts Preferred.
　なお、析出剤は、カルボン酸系析出剤に特に限定されず、炭酸ガス、炭酸アンモニウム、炭酸ナトリウム等の炭酸塩、水酸化ナトリウム、水酸化カリウム、水酸化アンモニウム等のアルカリ塩であってもよい。 The precipitating agent is not particularly limited to a carboxylic acid precipitant, and may be a carbonate such as carbon dioxide, ammonium carbonate, or sodium carbonate, or an alkali salt such as sodium hydroxide, potassium hydroxide, or ammonium hydroxide. .
　スカンジウムに対するカルボン酸系析出剤の割合は、１．０～５．０モルが好ましく、１．５～３．０モルがより好ましい。 The ratio of the carboxylic acid type precipitation agent to scandium is preferably 1.0 to 5.0 mol, and more preferably 1.5 to 3.0 mol.
　スカンジウムの析出操作は、析出装置を用いて、スカンジウムと析出剤とを適当な温度で一定時間、公知の手順で接触させて反応させる。得られた沈殿物はスカンジウム化合物であり、カルボン酸系析出剤を用いる場合の沈殿物はカルボン酸スカンジウムの化合物である。このスカンジウム化合物は、必要に応じて分別して回収する。分別操作は通常の装置で行うことができ、濾過機、静置分離機、遠心分離機等を用いることができる。 In the scandium precipitation operation, the scandium and the precipitating agent are brought into contact with each other at a suitable temperature for a certain period of time by a known procedure using a precipitation apparatus. The obtained precipitate is a scandium compound, and the precipitate when a carboxylic acid type precipitation agent is used is a compound of scandium carboxylate. The scandium compound is collected by separation as necessary. The fractionation operation can be performed with a normal apparatus, and a filter, a stationary separator, a centrifuge, or the like can be used.
　このようにして、有機溶媒抽出工程（ステップＳ３）、逆抽出工程（ステップＳ４）及び析出工程（ステップＳ５）を行うと、スカンジウムの純度を例えば９９.３質量％以上とすることができ、好ましくは９９．７質量％以上、より好ましくは９９．９質量％とすることができる。特に、トリウム、ウラン等を含む酸性水溶原液から、高純度にスカンジウムを分離することができる。 Thus, when the organic solvent extraction step (step S3), the back extraction step (step S4) and the precipitation step (step S5) are performed, the purity of scandium can be set to 99.3% by mass or more, for example. May be 99.7% by mass or more, more preferably 99.9% by mass. In particular, scandium can be separated with high purity from an acidic aqueous stock solution containing thorium, uranium and the like.
　（乾燥／焼成工程）
　次に、図１に示すように、スカンジウム化合物を乾燥及び／または焼成する（ステップＳ６：乾燥／焼成工程）。この工程（ステップＳ６）では、析出工程（ステップＳ５）で得られた沈殿物を乾燥及び／または焼成することにより、酸化スカンジウム等の粉末として回収することができる。なお、この工程（ステップＳ６）は省略されてもよい。 (Drying / Baking process)
Next, as shown in FIG. 1, the scandium compound is dried and / or baked (step S6: drying / baking step). In this step (step S6), the precipitate obtained in the precipitation step (step S5) can be recovered as a powder such as scandium oxide by drying and / or firing. Note that this step (step S6) may be omitted.
　乾燥条件及び／または焼成条件は適宜設定することができ、例えば、乾燥温度は８０～１５０℃程度が適当であり、乾燥時間は１～２４時間程度が適当である。また、例えば、焼成温度は３００～１２００℃程度であり、焼成時間は１～２４時間程度が適当である。 The drying conditions and / or firing conditions can be set as appropriate. For example, the drying temperature is suitably about 80 to 150 ° C., and the drying time is suitably about 1 to 24 hours. Further, for example, the firing temperature is about 300 to 1200 ° C., and the firing time is about 1 to 24 hours.
　続いて、本実施の形態のスカンジウムの分離方法において、ｐＨ調整工程（ステップＳ２）及び有機溶媒抽出工程（ステップＳ３）での反応機構について説明する。 Subsequently, in the scandium separation method of the present embodiment, the reaction mechanism in the pH adjustment step (step S2) and the organic solvent extraction step (step S3) will be described.
　ｐＨ調整工程（ステップＳ２）において、酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下に調整すると、下記の化学式１の右側への析出反応が起こる。
Ｓｃ3+＋３ＯＨ-⇔Ｓｃ（ＯＨ）3・・・・（化学式１） In the pH adjustment step (step S2), when an acidic aqueous stock solution and an alkali are mixed to adjust the pH to 4 or more and 7 or less, a precipitation reaction to the right side of the following chemical formula 1 occurs.
Sc 3+ + 3OH − ⇔Sc (OH) 3 ... (Chemical formula 1)
　化学式１は平衡状態であるので、第１酸性水溶液中の全てのスカンジウムがＳｃ（ＯＨ）3として沈殿しているのではなく、第１酸性水溶液中に溶解するＳｃ3+としても存在している。 Since Formula 1 is in an equilibrium state, not all scandium in the first acidic aqueous solution is precipitated as Sc (OH) 3 , but also exists as Sc 3+ dissolved in the first acidic aqueous solution. .
　有機溶媒抽出工程（ステップＳ３）におけるカルボン酸系抽出剤を用いたスカンジウムの抽出では、下記の化学式２に示すように、スカンジウムイオンとカルボン酸系抽出剤とが錯体を形成する。
Ｓｃ3+＋３ＨＡ⇔ＳｃＡ3＋３Ｈ+・・・・（化学式２）
なお、化学式２中、ＨＡはプロトン（Ｈ+）を有する抽出剤であり、Ａは炭素を含むアルキル基であり、ネオデカン酸の場合のＡ-はＣ9Ｈ19ＣＯＯ-である。 In the extraction of scandium using a carboxylic acid-based extractant in the organic solvent extraction step (step S3), as shown in the following chemical formula 2, the scandium ion and the carboxylic acid-based extractant form a complex.
Sc 3+ + 3HA⇔ScA 3 + 3H + (chemical formula 2)
In Chemical Formula 2, HA is an extractant having a proton (H + ), A is an alkyl group containing carbon, and A − in the case of neodecanoic acid is C 9 H 19 COO − .
　この錯体（ＳｃＡ3）は有機溶媒に可溶であるので、図２のＳ３に示すように、錯体が有機相に移動する。化学式２の右側への反応が促進されることによって、第１酸性水溶液中のスカンジウムを有機溶媒に移動することができる。 Since this complex (ScA 3 ) is soluble in an organic solvent, the complex moves to the organic phase as indicated by S3 in FIG. By promoting the reaction to the right side of Chemical Formula 2, scandium in the first acidic aqueous solution can be transferred to the organic solvent.
　ここで、化学式２において平衡が右に移動し、スカンジウムの抽出が起こるためには、抽出剤のプロトンが解離している必要がある。 Here, in order to move the equilibrium to the right in the chemical formula 2 and to extract scandium, the protons of the extractant need to be dissociated.
　有機溶媒中ではプロトンは解離せず、有機溶媒抽出工程（ステップＳ３）において、抽出剤（ＨＡ）と第１酸性水溶液中のＳｃ3+とが接触した時点で、下記の化学式３の反応が生じる。
ＨＡ⇔Ａ-＋Ｈ+・・・・（化学式３） Protons are not dissociated in the organic solvent, and in the organic solvent extraction step (step S3), when the extractant (HA) comes into contact with Sc 3+ in the first acidic aqueous solution, the reaction of the following chemical formula 3 occurs. .
HA⇔A − + H + ... (Chemical formula 3)
　化学式３において、ｐＨが高いほど平衡は右に移動し、スカンジウムイオンと錯体を形成できるＡ-が多くなる。ｐＨ調整工程（ステップＳ３）において酸性水溶原液のｐＨを４未満とすると、プロトンの解離が十分でなく、スカンジウムの抽出量が低下する。つまり、準備工程（ステップＳ１）で準備した第１酸性水溶液のｐＨが４未満の場合、第１酸性水溶原液と有機溶媒とを接触させると、プロトンの解離が十分でないため、スカンジウムの抽出量が低下する。このため、本実施の形態では、ｐＨ調整工程（ステップＳ２）において、第１酸性水溶原液とアルカリとを混合して、第１酸性水溶液のｐＨを４以上に調整することにより、化学式２において右側への反応を促進している。 In Chemical Formula 3, the higher the pH, the more the equilibrium moves to the right, and the more A − that can form complexes with scandium ions. When the pH of the acidic aqueous solution is less than 4 in the pH adjustment step (step S3), proton dissociation is not sufficient, and the amount of scandium extracted decreases. That is, when the pH of the first acidic aqueous solution prepared in the preparation step (step S1) is less than 4, when the first acidic aqueous solution is brought into contact with the organic solvent, protons are not sufficiently dissociated, so that the amount of scandium extracted is descend. Therefore, in the present embodiment, in the pH adjustment step (step S2), the first acidic aqueous solution and alkali are mixed to adjust the pH of the first acidic aqueous solution to 4 or more, so that the right side in Chemical Formula 2 Promotes reaction to
　なお、ｐＨが７を超える酸性水溶原液と有機溶媒とを接触させると、スカンジウムの抽出量が増えると共に、スカンジウム以外の不純物の抽出量の増えてしまう。このため、本実施の形態では、ｐＨ調整工程（ステップＳ２）において、第１酸性水溶原液とアルカリとを混合して、第１酸性水溶液のｐＨを７以下に調整している。 In addition, when the acidic aqueous undiluted solution having a pH of more than 7 is brought into contact with an organic solvent, the amount of scandium extracted increases and the amount of impurities other than scandium increases. For this reason, in this embodiment, in the pH adjustment step (step S2), the first acidic aqueous solution and alkali are mixed to adjust the pH of the first acidic aqueous solution to 7 or less.
　化学式２で溶解しているＳｃ3+が有機溶媒に抽出されると、系内のＳｃ3+が減少し、化学式１の平衡が左へ移動する。このため、化学式１における左側の反応、つまり、Ｓｃ（ＯＨ）3の一部が溶解してＳｃ3+が生じる反応が起こる。したがって、化学式２の右側への反応が促進され続けるとともに、ｐＨ調整工程（ステップＳ２）で水酸化物として存在するスカンジウムも有機溶媒に抽出されるので、高精度にスカンジウムの錯体（カルボン酸スカンジウム）を生成できる。 When Sc 3+ dissolved in Chemical Formula 2 is extracted into an organic solvent, Sc 3+ in the system decreases and the equilibrium of Chemical Formula 1 moves to the left. For this reason, a reaction on the left side in Chemical Formula 1, that is, a reaction in which a part of Sc (OH) 3 is dissolved to generate Sc 3+ occurs. Therefore, the reaction to the right side of Chemical Formula 2 continues to be promoted, and scandium present as a hydroxide in the pH adjustment step (Step S2) is also extracted into the organic solvent, so that the scandium complex (scandium carboxylate) is highly accurate. Can be generated.
　以上説明したように、本実施の形態におけるスカンジウムの分離方法は、スカンジウムを含有し、ｐＨが４未満の酸性水溶原液を準備する工程（ステップＳ１）と、酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整することにより、第１酸性水溶液を生成する工程（ステップＳ２）と、第１酸性水溶液と、カルボン酸及び／またはカルボン酸塩を抽出剤として含む有機溶媒とを接触させて、第１酸性水溶液中のスカンジウムを有機溶媒に移動することにより、スカンジウム含有有機溶媒を生成する工程（ステップＳ３）と、スカンジウム含有有機溶媒と、第２酸性水溶液とを接触させて、スカンジウム含有有機溶媒中のスカンジウムを第２酸性水溶液に移動することにより、スカンジウム含有水溶液を生成する工程（ステップＳ４）とを備えている。 As described above, the method for separating scandium in the present embodiment includes a step of preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4 (step S1), and mixing the acidic aqueous stock solution and an alkali. The organic solvent containing the process which produces | generates 1st acidic aqueous solution by adjusting pH to the range of 4-7 (step S2), 1st acidic aqueous solution, and carboxylic acid and / or carboxylate as an extractant And contacting the scandium in the first acidic aqueous solution with the organic solvent to produce the scandium-containing organic solvent (step S3), bringing the scandium-containing organic solvent into contact with the second acidic aqueous solution. And producing a scandium-containing aqueous solution by moving scandium in the scandium-containing organic solvent to the second acidic aqueous solution. Step S4) and a.
　本実施の形態におけるスカンジウムの分離方法によれば、準備工程（ステップＳ１）においてスカンジウムを含む原料として、ｐＨが４未満の酸性水溶原液を準備している。このため、難溶性のスカンジウム原料を用いても、酸性水溶原液中にスカンジウムイオンとして溶解させることができるので、酸性水溶原液中のスカンジウムの含有量の低下を抑制できる。このスカンジウムの含有量の低下を抑制した酸性水溶原液を用いて、有機溶媒抽出工程（ステップＳ３）前に、アルカリを用いてｐＨを４以上７以下の範囲に調整し、抽出剤としてナフテン酸、ネオデカン酸等のカルボン酸及び／またはその塩を用いて溶媒抽出することにより、チタン、ジルコニウム、バナジウムなど、及びスカンジウム以外の希土類元素等の不純物の抽出を低く抑えることができる。この効果は、本発明者らが鋭意検討した結果、上述したｐＨ調整工程（ステップＳ２）及び有機溶媒抽出工程（ステップＳ３）での反応機構の知見に想到し、見出した効果である。このため、特許文献１のようにスクラビング工程を実施しなくても、不純物を低減してスカンジウムを分離できる。また、抽出したスカンジウムを含有するスカンジウム含有有機溶媒と、硫酸、塩酸等の第２酸性水溶液とを接触させることにより、スカンジウムを第２酸性水溶液に移動することができる。したがって、生産性を向上してスカンジウムを分離することができる。 According to the scandium separation method in the present embodiment, an acidic aqueous stock solution having a pH of less than 4 is prepared as a raw material containing scandium in the preparation step (step S1). For this reason, even if a sparingly soluble scandium raw material is used, it can be dissolved as scandium ions in the acidic aqueous stock solution, so that a decrease in the content of scandium in the acidic aqueous stock solution can be suppressed. Using the acidic aqueous stock solution in which the decrease in the scandium content is suppressed, the pH is adjusted to a range of 4 to 7 using an alkali before the organic solvent extraction step (step S3), and naphthenic acid, By extracting with a solvent using a carboxylic acid such as neodecanoic acid and / or a salt thereof, extraction of impurities such as titanium, zirconium, vanadium, and rare earth elements other than scandium can be suppressed to a low level. As a result of intensive studies by the present inventors, this effect is an effect found by conceiving the knowledge of the reaction mechanism in the pH adjustment step (step S2) and the organic solvent extraction step (step S3) described above. For this reason, even if it does not carry out a scrubbing process like patent documents 1, impurities can be reduced and scandium can be separated. In addition, scandium can be transferred to the second acidic aqueous solution by bringing the extracted scandium-containing organic solvent containing scandium into contact with the second acidic aqueous solution such as sulfuric acid or hydrochloric acid. Therefore, productivity can be improved and scandium can be separated.
　また、本実施の形態のスカンジウムの分離方法において好ましくは、スカンジウム含有水溶液と、析出剤とを接触させて、スカンジウム化合物を析出する工程（ステップＳ５）をさらに備える。これにより、逆抽出工程（ステップＳ４）で得られたスカンジウム含有水溶液に、シュウ酸等のカルボン酸及び／またはその塩等を析出剤として混合しスカンジウム化合物を析出させることができるので、生産性を向上してスカンジウムを分離することができる。 The scandium separation method of the present embodiment preferably further includes a step (step S5) of bringing a scandium-containing aqueous solution and a precipitating agent into contact with each other to precipitate a scandium compound. As a result, the scandium-containing aqueous solution obtained in the back extraction step (step S4) can be mixed with a carboxylic acid such as oxalic acid and / or a salt thereof as a precipitating agent to precipitate a scandium compound. It can improve and separate scandium.
　また、本実施の形態のスカンジウムの分離方法において好ましくは、スカンジウム化合物を乾燥及び／または焼成する工程（ステップＳ６）をさらに備える。これにより、酸化スカンジウム等の粉末として回収することができる。 The scandium separation method of the present embodiment preferably further includes a step of drying and / or firing the scandium compound (step S6). Thereby, it can collect | recover as powder, such as a scandium oxide.
　逆抽出工程（ステップＳ４）を実施することにより分離されたスカンジウム含有水溶液と、ジルコニウム水溶液との混合により共沈殿物を形成させ、それを焼成してスカンジア安定化ジルコニアを製造することができる。また、乾燥／焼成工程（ステップＳ６）を実施することにより分離されたスカンジウムが水酸化スカンジウム、酸化スカンジウム等の粉末であれば、この粉末を、酸化ジルコニウムと混合し焼成してスカンジア安定化ジルコニアを製造することができる。本実施の形態におけるスカンジウムの分離方法によれば、生産性を向上しつつ、不純物を低減して純度が高くなるようにスカンジウムを分離することができる。つまり、本実施の形態におけるスカンジウムの分離方法によれば、高効率かつ簡便にスカンジウムを精製することができる。したがって、本実施の形態により得られたスカンジウムを用いたスカンジア安定化ジルコニアは固体酸化物燃料電池の電解質に有用であり、また、酸化スカンジウムを還元して金属にすることができ、また、ヨウ化してヨウ化スカンジウム等の化合物として用いることもできる。 A coprecipitate can be formed by mixing the scandium-containing aqueous solution separated by performing the back extraction step (step S4) and the zirconium aqueous solution, and calcined to produce scandia-stabilized zirconia. If the scandium separated by carrying out the drying / firing step (step S6) is a powder such as scandium hydroxide or scandium oxide, the powder is mixed with zirconium oxide and fired to obtain scandia-stabilized zirconia. Can be manufactured. According to the scandium separation method of the present embodiment, scandium can be separated so as to increase the purity by reducing impurities while improving productivity. That is, according to the scandium separation method of the present embodiment, scandium can be purified with high efficiency and ease. Therefore, scandia-stabilized zirconia using scandium obtained according to the present embodiment is useful for an electrolyte of a solid oxide fuel cell. Further, scandium oxide can be reduced to a metal, and iodide can be obtained. It can also be used as a compound such as scandium iodide.
　（実施の形態２）
　図３及び図４を参照して、本発明の実施形態２のスカンジウムの分離方法について説明する。 (Embodiment 2)
With reference to FIG.3 and FIG.4, the separation method of the scandium of Embodiment 2 of this invention is demonstrated.
　まず、図３及び図４に示すように、スカンジウムを含有し、ｐＨが４未満の酸性水溶原液を準備する（ステップＳ１：準備工程）。このステップＳ１は、実施の形態１と同様であるので、その説明を繰り返さない。 First, as shown in FIGS. 3 and 4, an acidic aqueous stock solution containing scandium and having a pH of less than 4 is prepared (step S1: preparation step). Since this step S1 is the same as that of Embodiment 1, the description thereof will not be repeated.
　次に、図３及び図４に示すように、酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整することにより、第１酸性水溶液を生成する（ステップＳ２：ｐＨ調整工程）。このステップＳ２は、実施の形態１と同様であるので、その説明を繰り返さない。 Next, as shown in FIG. 3 and FIG. 4, a first acidic aqueous solution is generated by mixing the acidic aqueous stock solution and the alkali and adjusting the pH to a range of 4 or more and 7 or less (step S2: pH). Adjustment process). Since this step S2 is the same as that of Embodiment 1, the description thereof will not be repeated.
　次に、図３及び図４に示すように、第１酸性水溶液と、カルボン酸及び／またはカルボン酸塩を抽出剤として含む有機溶媒とを接触させて、第１酸性水溶液中のスカンジウムを有機溶媒に移動することにより、スカンジウム含有有機溶媒を生成する（ステップＳ３：有機溶媒抽出工程）。 Next, as shown in FIGS. 3 and 4, the first acidic aqueous solution and an organic solvent containing carboxylic acid and / or carboxylate as an extractant are brought into contact with each other, so that scandium in the first acidic aqueous solution is converted into the organic solvent. To generate a scandium-containing organic solvent (step S3: organic solvent extraction step).
　本実施の形態では、実施の形態１の逆抽出工程（ステップＳ４：逆抽出工程）を省略し、次に、図３及び図４に示すように、スカンジウム含有有機溶媒と、析出剤とを接触させて、スカンジウム化合物を生成する（ステップＳ５：析出工程）。具体的には、抽出したスカンジウムを含む有機溶媒と析出剤とを混合して、スカンジウムを析出させる。このステップＳ５を実施することにより、スカンジウム含有有機溶媒中のスカンジウムと析出剤とが反応して、スカンジウム化合物が得られる。本実施の形態の逆抽出工程（ステップＳ４）は、析出剤と接触させる対象がスカンジウム含有有機溶媒である点において実施の形態１と異なり、それ以外は実施の形態１と同様である。 In the present embodiment, the back extraction step (step S4: back extraction step) of Embodiment 1 is omitted, and then, as shown in FIGS. 3 and 4, the scandium-containing organic solvent is contacted with the precipitation agent. To produce a scandium compound (step S5: precipitation step). Specifically, an organic solvent containing extracted scandium and a precipitant are mixed to precipitate scandium. By performing this step S5, the scandium in the scandium-containing organic solvent reacts with the precipitation agent to obtain a scandium compound. The back extraction process (step S4) of the present embodiment is different from the first embodiment in that the object to be contacted with the precipitation agent is a scandium-containing organic solvent, and the other processes are the same as in the first embodiment.
　次に、図３に示すように、スカンジウム化合物を乾燥及び／または焼成する（ステップＳ６：乾燥／焼成工程）。このステップＳ６は、実施の形態１と同様であるので、その説明を繰り返さない。なお、このステップＳ６は省略されてもよい。 Next, as shown in FIG. 3, the scandium compound is dried and / or baked (step S6: drying / baking step). Since this step S6 is the same as that of Embodiment 1, the description thereof will not be repeated. This step S6 may be omitted.
　以上の工程（ステップＳ１～Ｓ３、Ｓ５、Ｓ６）を実施することにより、生産性を向上してスカンジウムを分離することができる。このように、有機溶媒抽出工程（ステップＳ３）の後に、逆抽出工程（ステップＳ４）を実施せずに、析出工程（ステップＳ５）を行っても、スカンジウムの純度を例えば９９.０質量％以上、好ましくは９９．５質量％以上とすることができる。 By performing the above steps (steps S1 to S3, S5, S6), productivity can be improved and scandium can be separated. Thus, even if the precipitation step (step S5) is performed without performing the back extraction step (step S4) after the organic solvent extraction step (step S3), the purity of scandium is, for example, 99.0% by mass or more. , Preferably it can be 99.5 mass% or more.
　以下、本発明を実施例及び比較例により説明するが、本発明はそれらの実施例に限定されるものではない。 Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to these examples.
　（実施例１）
　まず、準備工程（ステップＳ１）として、不純物を含む水酸化スカンジウムを水に分散させ、硫酸を加えてｐＨ１．０に調整し、９０℃、３時間加熱することでスカンジウムを溶解させた酸性水溶原液を得た。 Example 1
First, as a preparation step (step S1), an acidic aqueous undiluted solution in which scandium hydroxide containing impurities is dispersed in water, sulfuric acid is added to adjust the pH to 1.0, and the scandium is dissolved by heating at 90 ° C. for 3 hours. Got.
　次に、ｐＨ調整工程（ステップＳ２）として、この酸性水溶原液に水酸化ナトリウムを加えてｐＨ６．５に調整した（第１酸性水溶液：試料Ａ）。 Next, as a pH adjustment step (step S2), sodium hydroxide was added to the acidic aqueous stock solution to adjust to pH 6.5 (first acidic aqueous solution: sample A).
　次に、有機溶媒抽出工程（ステップＳ３）として、この酸性水溶原液（水相）１００ｍＬと、ネオデカン酸（抽出剤）及びリン酸トリブチル（改質剤）をそれぞれ１０質量％及び３０質量％の濃度となるようケロシンに溶解させた有機溶剤１００ｍＬとを５００ｍＬ分液漏斗に入れ、２０分間縦型振とう機で混合し、スカンジウムを抽出した。振とう後、分液漏斗を静置し、有機相（スカンジウム含有有機溶媒）と水相（抽出後の第１酸性水溶液）とに分離させた。 Next, as an organic solvent extraction step (step S3), 100 mL of this acidic aqueous stock solution (aqueous phase), neodecanoic acid (extractant), and tributyl phosphate (modifier) at concentrations of 10% by mass and 30% by mass, respectively. Then, 100 mL of an organic solvent dissolved in kerosene was placed in a 500 mL separatory funnel and mixed with a vertical shaker for 20 minutes to extract scandium. After shaking, the separatory funnel was allowed to stand to separate into an organic phase (scandium-containing organic solvent) and an aqueous phase (first acidic aqueous solution after extraction).
　次いで、逆抽出工程（ステップＳ４）として、スカンジウムを抽出した有機相（スカンジウム含有有機溶媒）８０ｍＬと２Ｍ硫酸（第２酸性水溶液）２０ｍＬとを５００ｍＬ分液漏斗に入れ、２０分間縦型振とう機で混合し、スカンジウムを逆抽出した。振とう後、分液漏斗を静置し、有機相（逆抽出後の有機溶媒）と水相（スカンジウム含有水溶液：試料Ｂ）とを分離させた。 Next, as a back extraction step (step S4), 80 mL of the organic phase from which scandium was extracted (scandium-containing organic solvent) and 20 mL of 2M sulfuric acid (second acidic aqueous solution) were placed in a 500 mL separatory funnel, and a vertical shaker for 20 minutes And back-extracted scandium. After shaking, the separatory funnel was allowed to stand, and the organic phase (organic solvent after back extraction) and the aqueous phase (scandium-containing aqueous solution: sample B) were separated.
　ｐＨ調整工程（ステップＳ２）後または有機溶媒抽出工程（ステップＳ３）前の第１酸性水溶液（試料Ａ）及び逆抽出工程（ステップＳ４）後のスカンジウム含有水溶液（試料Ｂ）の各元素濃度を誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＡＥＳ）及び誘導結合プラズマ質量分析装置（ＩＣＰ－ＭＳ）でそれぞれ分析した。その結果をそれぞれ表１及び表２に示す。 Deriving the concentration of each element in the first acidic aqueous solution (sample A) after the pH adjustment step (step S2) or before the organic solvent extraction step (step S3) and the scandium-containing aqueous solution (sample B) after the back extraction step (step S4) Analysis was performed with a coupled plasma emission spectrometer (ICP-AES) and an inductively coupled plasma mass spectrometer (ICP-MS). The results are shown in Table 1 and Table 2, respectively.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表１及び表２に示すように、有機溶媒抽出工程（ステップＳ３）及び逆抽出工程（ステップＳ４）の実施によって、不純物元素が分離され、スカンジウムを高精度に分離できることが分かった。以上より、実施例１のスカンジウムの分離方法によれば、生産性を向上できることが確認できた。 As shown in Tables 1 and 2, it was found that by performing the organic solvent extraction step (Step S3) and the back extraction step (Step S4), the impurity elements were separated, and scandium could be separated with high accuracy. From the above, it was confirmed that according to the scandium separation method of Example 1, productivity could be improved.
　（実施例２）
　まず、準備工程（ステップＳ１）として、不純物を含む水酸化スカンジウムを水に分散させ、塩酸を加えてｐＨ１．０に調整し、９０℃、３時間加熱することでスカンジウムを溶解させた酸性水溶原液を得た。 (Example 2)
First, as a preparation step (step S1), an acidic aqueous stock solution in which scandium hydroxide containing impurities is dispersed in water, hydrochloric acid is added to adjust the pH to 1.0, and the scandium is dissolved by heating at 90 ° C. for 3 hours. Got.
　次に、ｐＨ調整工程（ステップＳ２）として、その水溶液に水酸化ナトリウムを加えてｐＨ６．０に調整した。 Next, as a pH adjustment step (step S2), sodium hydroxide was added to the aqueous solution to adjust to pH 6.0.
　次に、実施例１と同様に、有機溶媒抽出工程（ステップＳ３）及び逆抽出工程（ステップＳ４）を実施して、スカンジウムの抽出及び逆抽出を行い、抽出前の水相（第１酸性水溶液：試料Ｃ）及び逆抽出後の水相（スカンジウム含有水溶液：試料Ｄ）を得た。 Next, in the same manner as in Example 1, the organic solvent extraction step (step S3) and the back extraction step (step S4) are performed to extract scandium and back extract, and the aqueous phase (first acidic aqueous solution before extraction) is extracted. : Sample C) and an aqueous phase after back extraction (Scandium-containing aqueous solution: Sample D) were obtained.
　ｐＨ調整工程（ステップＳ２）後または有機溶媒抽出工程（ステップＳ３）前の水相、すなわち第１酸性水溶液（試料Ｃ）及び逆抽出工程（ステップＳ４）後のスカンジウム含有水溶液（試料Ｄ）の各元素濃度を誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＡＥＳ）及び誘導結合プラズマ質量分析装置（ＩＣＰ－ＭＳ）でそれぞれ分析した。その結果をそれぞれ表３及び表４に示す。 The aqueous phase after the pH adjustment step (step S2) or before the organic solvent extraction step (step S3), that is, each of the first acidic aqueous solution (sample C) and the scandium-containing aqueous solution (sample D) after the back extraction step (step S4) Elemental concentrations were analyzed with an inductively coupled plasma emission spectrometer (ICP-AES) and an inductively coupled plasma mass spectrometer (ICP-MS), respectively. The results are shown in Table 3 and Table 4, respectively.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　表３及び表４に示すように、有機溶媒抽出工程（ステップＳ３）及び逆抽出工程（ステップＳ４）の実施によって、不純物元素が分離され、スカンジウムを高精度に分離できることが分かった。以上より、実施例２のスカンジウムの分離方法によれば、生産性を向上できることが確認できた。 As shown in Tables 3 and 4, it was found that by performing the organic solvent extraction step (Step S3) and the back extraction step (Step S4), the impurity elements were separated and scandium could be separated with high accuracy. From the above, it was confirmed that according to the scandium separation method of Example 2, productivity could be improved.
　（実施例３）
　実施例３では、析出工程（ステップＳ５）をさらに実施した。具体的には、実施例１の試料Ｂ及び実施例２の試料Ｄのスカンジウム含有水溶液と、析出剤としてのシュウ酸（スカンジウムに対して１．５モル倍）とを反応槽で混合しスカンジウム化合物としてのシュウ酸スカンジウムを析出させた。 Example 3
In Example 3, the precipitation step (Step S5) was further performed. Specifically, the scandium-containing aqueous solution of Sample B of Example 1 and Sample D of Example 2 and oxalic acid (1.5 mol times with respect to scandium) as a precipitating agent were mixed in a reaction vessel to obtain a scandium compound. As a result, scandium oxalate was deposited.
　次に、スカンジウム化合物を含有する水溶液を濾過し、乾燥し、９００℃の温度で焼成して酸化スカンジウムを回収した（試料Ｅ及びＦ）。 Next, the aqueous solution containing the scandium compound was filtered, dried, and calcined at a temperature of 900 ° C. to recover scandium oxide (samples E and F).
　試料Ｅ及びＦの各元素濃度を誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＡＥＳ）及び誘導結合プラズマ質量分析装置（ＩＣＰ－ＭＳ）で分析した結果、スカンジウムの純度は９９．９質量％であることが分かった。以上より、実施例３のスカンジウムの分離方法によれば、生産性を向上できることが確認できた。 As a result of analyzing each element concentration of samples E and F with an inductively coupled plasma emission spectrometer (ICP-AES) and an inductively coupled plasma mass spectrometer (ICP-MS), the purity of scandium is 99.9% by mass. I understood. From the above, it was confirmed that according to the scandium separation method of Example 3, productivity could be improved.
　さらに、実施例３で得られたシュウ酸スカンジウム沈殿物、その乾燥物、及び焼成した酸化スカンジウムを公知の方法により処理してスカンジア安定化ジルコニアを製造することができることを確認した。さらに、それらは固体酸化物燃料電池の電解質として作用することを確認した。 Furthermore, it was confirmed that scandia-stabilized zirconia can be produced by treating the scandium oxalate precipitate obtained in Example 3, its dried product, and calcined scandium oxide by a known method. Furthermore, they have been confirmed to act as electrolytes for solid oxide fuel cells.
　（実施例４）
　まず、準備工程（ステップＳ１）として、不純物を含む水酸化スカンジウムを水に分散させ、硫酸を加えてｐＨ０．５に調整し、スカンジウムを溶解させた。次いでアンモニア水を加えてｐＨ２．５に調整し、９０℃、１時間加熱し、チタンなどの不純物を水酸化物として析出させた。これをろ過し、ろ液を回収することで酸性水溶原液を得た。 Example 4
First, as a preparation process (step S1), scandium hydroxide containing impurities was dispersed in water, and sulfuric acid was added to adjust the pH to 0.5 to dissolve scandium. Next, aqueous ammonia was added to adjust the pH to 2.5, and the mixture was heated at 90 ° C. for 1 hour to precipitate impurities such as titanium as hydroxides. This was filtered, and the filtrate was collected to obtain an acidic aqueous stock solution.
　次に、ｐＨ調整工程（ステップＳ２）として、この酸性水溶原液にアンモニア水を加えてｐＨ６．５に調整した（第１酸性水溶液：試料Ｇ）。 Next, as a pH adjustment step (step S2), ammonia water was added to the acidic aqueous stock solution to adjust to pH 6.5 (first acidic aqueous solution: sample G).
　次に、有機溶媒抽出工程（ステップＳ３）として、この酸性水溶原液（水相）１５ｍＬと、ネオデカン酸（抽出剤）及びリン酸トリブチル（改質剤）をそれぞれ１０質量％及び３０質量％の濃度となるようケロシンに溶解させた有機溶剤１５ｍＬとを５０ｍＬ遠沈管に入れ、２０分間縦型振とう機で混合し、スカンジウムを抽出した。振とう後、遠沈管を静置し、有機相（スカンジウム含有有機溶媒）と水相（抽出後の第１酸性水溶液：試料Ｈ）とに分離させた。 Next, as an organic solvent extraction step (step S3), 15 mL of this acidic aqueous stock solution (aqueous phase), neodecanoic acid (extractant), and tributyl phosphate (modifier) at concentrations of 10% by mass and 30% by mass, respectively. Then, 15 mL of an organic solvent dissolved in kerosene was placed in a 50 mL centrifuge tube and mixed with a vertical shaker for 20 minutes to extract scandium. After shaking, the centrifuge tube was allowed to stand and separated into an organic phase (scandium-containing organic solvent) and an aqueous phase (first acidic aqueous solution after extraction: sample H).
　次いで、逆抽出工程（ステップＳ４）として、スカンジウムを抽出した有機相（スカンジウム含有有機溶媒）１０ｍＬと０．４Ｎ塩酸（第２酸性水溶液）１０ｍＬとを５０ｍＬ遠沈管に入れ、２０分間縦型振とう機で混合し、スカンジウムを逆抽出した。振とう後、遠沈管を静置し、有機相（逆抽出後の有機溶媒）と水相（スカンジウム含有水溶液：試料Ｉ）とを分離させた。 Next, as a back extraction step (step S4), 10 mL of the organic phase from which scandium was extracted (scandium-containing organic solvent) and 10 mL of 0.4N hydrochloric acid (second acidic aqueous solution) were placed in a 50 mL centrifuge tube and shaken vertically for 20 minutes. Mix in the machine and back-extract scandium. After shaking, the centrifuge tube was allowed to stand, and the organic phase (organic solvent after back extraction) and the aqueous phase (scandium-containing aqueous solution: sample I) were separated.
　試料Ｇ、試料Ｈ及び試料Ｉの各元素濃度を誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＡＥＳ）で分析した。その結果を表５に示す。 The element concentrations of Sample G, Sample H, and Sample I were analyzed with an inductively coupled plasma emission spectrometer (ICP-AES). The results are shown in Table 5.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
　実施例１及び２と同様、有機溶媒抽出工程（ステップＳ３）及び逆抽出工程（ステップＳ４）の実施によって、不純物元素が分離され、スカンジウムを高精度に分離できることが分かった。また逆抽出工程でのスカンジウム回収率は９０％程度と高い値であった。 As in Examples 1 and 2, it was found that by performing the organic solvent extraction step (step S3) and the back extraction step (step S4), the impurity element was separated, and scandium could be separated with high accuracy. Further, the scandium recovery rate in the back extraction process was as high as about 90%.
　（実施例５）
　有機溶媒抽出工程（ステップＳ３）において、有機溶剤としてネオデカン酸（抽出剤）のみを１０質量％の濃度となるようケロシンに溶解させたものを用いる以外は、実施例４と同様にして準備工程（ステップＳ１）、ｐＨ調整工程（ステップＳ２）、有機溶媒抽出工程（ステップＳ３）、逆抽出工程（ステップＳ４）を実施し、抽出後の第１酸性水溶液（試料Ｊ）及び逆抽出後のスカンジウム含有水溶液（試料Ｋ）を得た。 (Example 5)
In the organic solvent extraction step (step S3), a preparation step (same as in Example 4) except that only neodecanoic acid (extractant) dissolved in kerosene so as to have a concentration of 10% by mass is used as the organic solvent. Step S1), pH adjustment step (Step S2), organic solvent extraction step (Step S3), back extraction step (Step S4) are carried out, first acidic aqueous solution (sample J) after extraction and scandium containing after back extraction An aqueous solution (Sample K) was obtained.
　試料Ｊ及び試料Ｋの各元素濃度を誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＡＥＳ）で分析した。その結果を表６に示す。 The element concentrations of Sample J and Sample K were analyzed with an inductively coupled plasma emission spectrometer (ICP-AES). The results are shown in Table 6.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　有機溶媒に改質剤（リン酸トリブチル）を添加しない場合でも、逆抽出工程（ステップＳ４）後のスカンジウム含有水溶液中の不純物は低減していたが、実施例５の試料Ｋは実施例４の試料Ｉに比べるとスカンジウム濃度は低いことが分かった。実施例５と実施例４の結果から、有機溶媒への改質剤（リン酸トリブチル）の添加は、逆抽出工程（ステップＳ４）での回収効率の向上に寄与していることが分かった。しかしながら、実施例５の改質剤（リン酸トリブチル）を使用しない場合は、逆抽出工程を複数回繰り返すことによりスカンジウム濃度は高くなり、回収は可能であることを確認した。 Even when the modifier (tributyl phosphate) was not added to the organic solvent, the impurities in the scandium-containing aqueous solution after the back extraction step (step S4) were reduced, but the sample K of Example 5 was the sample K of Example 4. Compared to Sample I, the scandium concentration was found to be low. From the results of Example 5 and Example 4, it was found that the addition of the modifier (tributyl phosphate) to the organic solvent contributed to the improvement of the recovery efficiency in the back extraction step (Step S4). However, when the modifier of Example 5 (tributyl phosphate) was not used, it was confirmed that the scandium concentration was increased by repeating the back extraction step a plurality of times, and the recovery was possible.
　（比較例１及び２）
　実施例１及び２において、それぞれ得た酸性水溶原液をそのｐＨのまま有機溶媒抽出を行ったこと以外は、実施例１及び２と同様にして、図２の逆抽出工程（ステップＳ４）の右側の「Ｓｃ含有水溶液」で表した相に対応する相として、比較例１の試料Ｌ及び比較例２の試料Ｍを得た。つまり、比較例１及び２では、ｐＨ調整工程（ステップＳ２）を実施しなかったので、ｐＨが１．０の酸性水溶原液と、カルボン酸系抽出剤を含む有機溶媒とを接触させた。 (Comparative Examples 1 and 2)
In Examples 1 and 2, the right side of the back extraction step (step S4) in FIG. 2 was performed in the same manner as in Examples 1 and 2, except that the obtained acidic aqueous solution was subjected to organic solvent extraction while maintaining its pH. The sample L of the comparative example 1 and the sample M of the comparative example 2 were obtained as a phase corresponding to the phase represented by "Sc containing aqueous solution". That is, in Comparative Examples 1 and 2, since the pH adjustment step (Step S2) was not performed, the acidic aqueous solution having a pH of 1.0 and an organic solvent containing a carboxylic acid-based extractant were brought into contact.
　（比較例３及び４）
　実施例１及び２において、抽出剤として２－エチルヘキシルホスホン酸－モノ－２－エチルヘキシルを使用したこと以外は実施例１及び２と同様にして、図２の逆抽出工程（ステップＳ４）の右側の「Ｓｃ含有水溶液」で表した相に対応する相として、比較例３の試料Ｎ及び比較例４の試料Ｏを得た。つまり、比較例３及び４では、ｐＨ調整工程（ステップＳ２）を実施した第１酸性水溶液と、カルボン酸系抽出剤を含まない有機溶媒とを接触させた。 (Comparative Examples 3 and 4)
In Examples 1 and 2, in the same manner as in Examples 1 and 2, except that 2-ethylhexylphosphonic acid-mono-2-ethylhexyl was used as an extractant, the right side of the back extraction step (step S4) in FIG. Sample N of Comparative Example 3 and Sample O of Comparative Example 4 were obtained as phases corresponding to the phase represented by “Sc-containing aqueous solution”. That is, in the comparative examples 3 and 4, the 1st acidic aqueous solution which implemented the pH adjustment process (step S2) and the organic solvent which does not contain a carboxylic acid type extractant were made to contact.
　逆抽出工程後の水相（試料Ｌ～Ｏ）の各元素濃度を誘導結合プラズマ発光分光分析装置（ＩＣＰ－ＡＥＳ）及び誘導結合プラズマ質量分析装置（ＩＣＰ－ＭＳ）でそれぞれ分析した。 Each elemental concentration of the aqueous phase (samples L to O) after the back extraction step was analyzed with an inductively coupled plasma emission spectrometer (ICP-AES) and an inductively coupled plasma mass spectrometer (ICP-MS).
　その結果、比較例１及び２の試料Ｌ及びＭからはスカンジウムも不純物も検出されず、比較例３及び４の試料Ｎ及びＯからはスカンジウムは検出されなかったが、イットリウムなどの不純物が検出された。これは、比較例１及び２では水相のｐＨが低く、スカンジウム及び不純物が有機相（図２の有機溶媒抽出工程（ステップＳ３）の右側の「Ｓｃ含有有機溶媒」で表した相に対応する相）に抽出されなかったことを示していると考えられる。一方、比較例３及び４ではスカンジウムは不純物と共に有機相（図２のＳ３の「Ｓｃ含有有機溶媒」で表した相に対応する相）に抽出されたものの、第２酸性水溶液でスカンジウムが逆抽出できなかったことを示していると考えられる。 As a result, scandium and impurities were not detected from samples L and M of Comparative Examples 1 and 2, and scandium was not detected from Samples N and O of Comparative Examples 3 and 4, but impurities such as yttrium were detected. It was. This corresponds to the phase represented by the “Sc-containing organic solvent” on the right side of the organic phase (the organic solvent extraction step (step S3) in FIG. 2) in which the pH of the aqueous phase is low in Comparative Examples 1 and 2. It is thought that it was not extracted in (phase). On the other hand, in Comparative Examples 3 and 4, although scandium was extracted together with impurities into the organic phase (the phase corresponding to the “Sc-containing organic solvent” of S3 in FIG. 2), scandium was back-extracted with the second acidic aqueous solution. It is thought that it was not possible.
　本発明のスカンジウムの分離方法で分離したスカンジウムは、生産性を向上して分離され、かつ不純物が少なく純度が高いため、種々の用途に用いることができる。具体的には、固体酸化物燃料電池の電解質に有用なスカンジア安定化ジルコニア等を製造することができる。 The scandium separated by the scandium separation method of the present invention can be used in various applications because it is separated with improved productivity and is low in impurities and high in purity. Specifically, scandia-stabilized zirconia and the like useful for an electrolyte of a solid oxide fuel cell can be produced.
　今回開示された実施の形態及び実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した実施の形態及び実施例ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 It should be considered that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is shown not by the above-described embodiments and examples but by the scope of claims, and is intended to include meanings equivalent to the scope of claims and all modifications within the scope.

Claims (11)

  1. 　スカンジウムを含有し、ｐＨが４未満の酸性水溶原液を準備する工程と、
    　前記酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整することにより、第１酸性水溶液を生成する工程と、
    　前記第１酸性水溶液と、カルボン酸及び／またはカルボン酸塩を抽出剤として含む有機溶媒とを接触させて、前記第１酸性水溶液中のスカンジウムを前記有機溶媒に移動することにより、スカンジウム含有有機溶媒を生成する工程と、
    　前記スカンジウム含有有機溶媒と、第２酸性水溶液とを接触させて、前記スカンジウム含有有機溶媒中のスカンジウムを前記第２酸性水溶液に移動することにより、スカンジウム含有水溶液を生成する工程とを備える、スカンジウムの分離方法。     Preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4;
    A step of producing a first acidic aqueous solution by mixing the acidic aqueous stock solution and an alkali and adjusting the pH to a range of 4 or more and 7 or less;
    By bringing the first acidic aqueous solution into contact with an organic solvent containing a carboxylic acid and / or a carboxylate as an extractant, and moving scandium in the first acidic aqueous solution to the organic solvent, a scandium-containing organic solvent Generating
    A step of forming a scandium-containing aqueous solution by bringing the scandium-containing organic solvent into contact with a second acidic aqueous solution and moving scandium in the scandium-containing organic solvent to the second acidic aqueous solution. Separation method.
  2. 　前記スカンジウム含有水溶液と、析出剤とを接触させて、スカンジウム化合物を析出する工程をさらに備える、請求項１に記載のスカンジウムの分離方法。 The method for separating scandium according to claim 1, further comprising a step of bringing the scandium-containing aqueous solution into contact with a precipitation agent to precipitate a scandium compound.
  3. 　スカンジウムを含有し、ｐＨが４未満の酸性水溶原液を準備する工程と、
    　前記酸性水溶原液とアルカリとを混合して、ｐＨを４以上７以下の範囲に調整することにより、第１酸性水溶液を生成する工程と、
    　前記第１酸性水溶液と、カルボン酸及び／またはカルボン酸塩を抽出剤として含む有機溶媒とを接触させて、前記第１酸性水溶液中のスカンジウムを前記有機溶媒に移動することにより、スカンジウム含有有機溶媒を生成する工程と、
    　前記スカンジウム含有有機溶媒と、析出剤とを接触させて、スカンジウム化合物を生成する工程とを備える、スカンジウムの分離方法。     Preparing an acidic aqueous stock solution containing scandium and having a pH of less than 4;
    A step of producing a first acidic aqueous solution by mixing the acidic aqueous stock solution and an alkali and adjusting the pH to a range of 4 or more and 7 or less;
    By bringing the first acidic aqueous solution into contact with an organic solvent containing a carboxylic acid and / or a carboxylate as an extractant, and moving scandium in the first acidic aqueous solution to the organic solvent, a scandium-containing organic solvent Generating
    A method for separating scandium, comprising: bringing the scandium-containing organic solvent into contact with a precipitation agent to produce a scandium compound.
  4. 　前記析出剤は、カルボン酸及び／またはカルボン酸塩である、請求項２または３に記載のスカンジウムの分離方法。 The method for separating scandium according to claim 2 or 3, wherein the precipitating agent is a carboxylic acid and / or a carboxylate.
  5. 　前記スカンジウム化合物を乾燥及び／または焼成する工程をさらに備える、請求項２～４のいずれか１項に記載のスカンジウムの分離方法。 The method for separating scandium according to any one of claims 2 to 4, further comprising a step of drying and / or calcining the scandium compound.
  6. 　前記抽出剤は、ナフテン酸及び／またはネオデカン酸である、請求項１～５のいずれか１項に記載のスカンジウムの分離方法。 The scandium separation method according to any one of claims 1 to 5, wherein the extractant is naphthenic acid and / or neodecanoic acid.
  7. 　前記有機溶媒は、改質剤をさらに含む、請求項１～６のいずれか１項に記載のスカンジウムの分離方法。 The method for separating scandium according to any one of claims 1 to 6, wherein the organic solvent further contains a modifier.
  8. 　前記改質剤は、リン酸トリブチルである、請求項７に記載のスカンジウムの分離方法。 The method for separating scandium according to claim 7, wherein the modifier is tributyl phosphate.
  9. 　前記酸性水溶原液は、チタン、ジルコニウム、バナジウム及びスカンジウム以外の希土類元素から選ばれる少なくとも一種の金属イオンをさらに含む、請求項１～８のいずれか一項に記載のスカンジウムの分離方法。 The method for separating scandium according to any one of claims 1 to 8, wherein the acidic aqueous solution further contains at least one metal ion selected from rare earth elements other than titanium, zirconium, vanadium and scandium.
  10. 　前記酸性水溶原液は、鉱石及び／または鉱石の残滓を酸で溶解した水溶液である、請求項１～９のいずれか１項に記載のスカンジウムの分離方法。 10. The method for separating scandium according to claim 1, wherein the acidic aqueous stock solution is an aqueous solution in which ore and / or residue of the ore are dissolved with an acid.
  11. 　前記酸性水溶原液は、スカンジウムを含む水性スラリーと酸とを混合して、ｐＨを２以下に調整した水溶液である、請求項１～１０のいずれか１項に記載のスカンジウムの分離方法。 The method for separating scandium according to any one of claims 1 to 10, wherein the acidic aqueous solution is an aqueous solution in which an aqueous slurry containing scandium and an acid are mixed to adjust the pH to 2 or less.
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