PURIFICATION OF NIOBIUM OXIDE

摘要

PROBLEM TO BE SOLVED: To continuously carry out the purification of niobium oxide of several times to several ten times as much as ion exchange capacity by adjusting the concentration of niobium of an aqueous solution of hydrofluoric acid containing tantalum and niobium as ions to a specific value or a smaller than it and circulating the aqueous solution through an anion exchange resin. SOLUTION: The concentration of niobium in an aqueous solution of hydrofluoric acid is <=60 g/l calculated as niobium pentoxide. Crude niobium oxide containing a tantalum component is treated with hydrofluoric acid of <=15 times the molar amount of niobium oxide and tantalum (e.g. >=80% highly concentrated hydrofluoric acid) to dissolve tantalum and niobium. An undissolved substance is separated and removed and the solution is mixed with water and hydrofluoric acid and adjusted to a fixed concentration. High-purity niobium and tantalum can be readily recovered by previously removing a metal (cation) to become an impurity in a solution to be treated. An ore or a niobium alloy containing niobium and tantalum or industrial niobium oxide having about 98% purity can be purified by the method.