GB805501A - Improvements in or relating to the production of niobium and tantalum compounds - Google Patents

Abstract

Niobium and tantalum values are recovered in the form of a solution of potassium niobate and tantalate from iron containing source materials by heating, preferably to about 120 DEG C., with an aqueous solution of potassium hydroxide, preferably containing at least 50 per cent KOH by weight, under reducing conditions such that the formation of ferric hydroxide is substantially prevented, preferably by heating in the presence of metallic iron which does not introduce further impurities. Subsequently to said heating step, precautions are taken to avoid formation of ferric hydroxide while the hot alkaline potassium niobate and tantalate solution is in contact with the insoluble matter. The method is particularly applicable to the treatment of ferrotantalum and ferroniobium, in which cases it is only necessary to add a little extra iron towards the end of the reaction. The solution of potassium tantalate and niobate is then separated from the insoluble residue consisting chiefly of Fe3O4. The solution may now either be treated with hydrogen fluoride, to convert the niobate and tantalate to the complex fluorides K2NbOF5H2O and K2TaF7, which may readily be separated by utilizing their differing solubilities, or alternatively the solution may be concentrated to obtain a solid mixture of potassium niobate and tantalate, which is then converted to the complex fluorides and separated in the usual manner.