Method of purifying tantalum

摘要

A method for obtaining high-purity tantalum pentoxide is disclosed, which comprises the following steps: dissolving a crude tantalum-containing compound in an acid containing hydrofluoric acid; mixing and bringing the resulting acidic aqueous solution of the crude tantalum-containing compound into contact with an organic solution composed of a water-insoluble quaternary ammonium compound and a water-insoluble organic solvent, to extract the tantalum from said acidic aqueous solution into said organic solution; mixing said organic solution with an aqueous solution containing at least one compound selected from the group consisting of an inorganic acid and an ammonium salt, to remove any of the impurities that have partly been extracted into said organic solution together with tantalum from said organic solution; converting the tantalum in said organic solution to tantalum hydroxide by treatment with an alkali containing ammonium hydroxide; and precipitating said tantalum hydroxide and separating it, followed by calcining it to obtain high-purity tantalum pentoxide. The tantalum pentoxide has an extremely high purity as five to six nines (99.999% to 99.9999%).