Method for refining hydroxides of niobium and tantalum containin

Details Method for refining hydroxides of niobium and tantalum containin Method for refining hydroxides of niobium and tantalum containin

1989-06-02

1990-07-17

Stoll, Robert L.

Chemistry of inorganic compounds

Treating mixture to obtain metal containing compound

Group vb metal

423 67, 423 68, 423 56, 423 81, 423143, 423 42, 423 50, 423 92, C01G 3300, C01G 3500

Patent

active

049420240

ABSTRACT:
Refining of either niobium hydroxide or tantalum hydroxide containing transition metals as impurities is accomplished easily and economically by dissolving the metal hydroxide in an aqueous solution of either hydrofluoric acid or oxalic acid, adjusting the pH of the solution to 1 to 4 and adding ammonium pyrrolidinedithiocarbamate (APDC) to the solution while maintaining the temperature of the solution below 60.degree. C. The addition of APDC causes the transition metals to simultaneously precipitate as coordination compounds. The minimum amount of APDC is 0.05 wt % of Nb.sub.2 O.sub.5 or Ta.sub.2 O.sub.5 that can be formed from Nb or Ta contained in the solution. After the treatment with APDC the pH of the solution is raised to 6 or above to precipitate the refined metal hydroxide.

REFERENCES:
patent: 4465593 (1984-08-01), Wemhoff
patent: 4490340 (1984-12-01), Ritsko
patent: 4495158 (1985-01-01), Ritsko

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