| 摘要 |
PURPOSE:To simplify a process and also to improve yield, by carrying out solvent extraction, back-extraction, Ta extraction, etc., and forming Nb halide at the time of producing Nb from a mixed solution of HF and sulfuric acid containing metallic impurities such as Nb, Ta. CONSTITUTION:(a) An organic solvent is brought into contact with the above-mentioned mixed solution to carry out the selective extraction of Nb and Ta, and the organic solvent is brought into contact with an aqueous solution containing NH3 and HF so as to extract Nb and Ta to the aqueous-solution side. (b) An organic solvent or adsorbent is brought into contact with the above aqueous solution to remove Ta by selective extraction or adsorption. (c) NH3 gas and NH4OH or KOH and KF are added to the Nb-containing aqueous solution from which back-extracted Ta ions are removed so as to form a precipitate containing Nb, F<-> and NH<+> or K<+>. (d) One or more kinds among sulfuric acid, hydrochloric acid, HF, etc., are added to the above precipitate and/or the Nb-containing aqueous solution prepared in stage (b) to dissolve the precipitate and also to regulate pH, with which one or more kinds among O- containing organic solvents, such as ester and ether, are brought into contact. Then, Nb halide is extracted in the above solvents, and, after the solvents are removed, the Nb halide is brought into contact with Na, Ca, etc., so as to be formed into Nb.
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