The effect of oxalate concentration and pH of the solution on complete precipitability of tantalum-tannin complex and its determination by molecular absorption spectrophotometry

The elements Niobium (Columbium) and Tatalum are closely associated together in their minerals and their separation is found to be extremely difficult because of their close resemblance in chemical properties and also the modification of the properties of one by the presence of the other. The frequent co-existence of Titanium in their ores induces additional difficulties to the problem. Attempts have been made to arrive conditions for the complete precipitation of Tatalum and Niobium from Oxalate solutions at different pH with Tannin. It has been found that at pH 4 and 2% Ammonium Oxalate solution, Tantalum can be separated from Niobium in one precipitation with Tannin if the ratio of Ta2O5 to Nb2O5 is 6:1 or higher and in the case of lower ratio, a second precipitation is required.