Process for the recovery of tantalum values

A process for recovery of tantalum from an impure source containing tungsten, titanium, iron, and other impurities, said process comprising:

• (a) mixing said impure source with an alkali metal carbonate to form a mixture;
• (b) drying said mixture,
• (c) heating the dried mixture at a sufficient temperature and for a sufficient time to convert said tungsten impurities to a water soluble form and form a resulting mixture,
• (d) leaching the resulting mixture with water to form a two phase system in which the liquid phase contains tungsten values and the solid phase contains the tantalum values and other impurities,
• (e) separating said liquid phase containing the tungsten values from said solid phase containing the tantalum values and other impurities,
• (f) digesting said solid phase containing the tantalum values and other impurities in a hydrochloric acid solution of sufficient strength, at a sufficient temperature and for a sufficient time to solubilize iron and a portion of the titanium impurities and form a liquid phase comprising iron and titanium,
• (g) separating the liquid phase comprising iron and titanium from the resulting solid phase containing the tantalum values and depleted titanium values,
• (h) contacting said resulting solid phase with an aqueous solution of hydrofluoric acid of sufficient strength to solubilize said tantalum values and titanium values,
• (i) separating the resulting hydrofluoric acid solution containing said tantalum values and titanium values from any insolubles,
• (j) adjusting the pH of said hydrofluoric acid solution containing said tantalum values and said titanium values from about 6.0 to about 8.0 with a base to form a first tantalum precipitate whereby a major portion of said titanium values remain in the resulting solution,
• (k) separating the first tantalum precipitate from said resulting first solution,
• (i) dissolving said first tantalum precipitate in an aqueous solution of oxalic acid of sufficient strength to solubilize the tantalum values,
• (m) separating the resulting oxalic acid solution containing the tantalum values and said minor portion of titanium from the resulting insolubles,
• (n) adjusting the pH of said oxalic acid solution to from about 6.5 to about 7.0 with a base to form a second tantalum precipitate and a second solution,
• (o) separating said second tantalum precipitate from the second solution,
• (p) dissolving said second tantalum precipitate in hydrochloric acid, and
• (q) digesting the resulting hydrochloric acid solution containing tantalum values at a sufficient temperature and for a sufficient time to form a two phase system including a solid phase consisting of a third tantalum precipitate of high purity.