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US 5,635,146 AGranted
Method for the dissolution and purification of tantalum pentoxide
AssigneeOsram Sylvania Inc.
InventorsRaj P. Singh, Michael J. Miller
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AssigneeOsram Sylvania Inc.
InventorsRaj P. Singh, Michael J. Miller
Estimating the term…
A method is disclosed for the dissolution and purification of tantalum pentoxide. The impure tantalum pentoxide is reacted with a potassium-containing compound to form potassium tantalate. The potassium tantalate is optionally slurried with sulfuric acid and dissolved in an HF medium. The solution is suitable for purification by conventional ion exchange or solvent extraction methods. A potassium fluorotantalate precipitate may also be formed by adding KCl to the solution. The fluorotantalate precipitate may be further processed into a pure tantalum pentoxide by suspending the precipitate in an aqueous solution optionally containing a chelating agent and adding ammonium hydroxide to form ammonium tantalum oxide which can then be converted to tantalum pentoxide by calcining at high temperature.
A method for the dissolution and purification of tantalum pentoxide comprising reacting tantalum pentoxide and a potassium-containing compound to form potassium tantalate, dissolving the potassium tantalate in a hydrofluoric acid medium to form a solution containing tantalum values and impurities and separating the tantalum values from the impurities.
A method for the dissolution and purification of tantalum pentoxide comprising reacting stoichiometric amounts of an impure tantalum pentoxide and potassium carbonate to form potassium tantalate, optionally slurrying the potassium tantalate with sulfuric acid, dissolving the potassium tantalate in an hydrofluoric acid medium to form a solution containing tantalum values and impurities, precipitating potassium fluorotantalate by adding a water soluble potassium compound, filtering the solution to obtain a wet precipitate, suspending the wet precipitate in water, optionally adding an effective amount of a chelating agent, precipitating (NH.sub.4).sub.2 Ta.sub.2 O.sub.6 .multidot.H.sub.2 O by adding ammonium hydroxide and calcining the (NH.sub.4).sub.2 Ta.sub.2 O.sub.6 .multidot.H.sub.2 O to obtain a tantalum pentoxide having low amounts of niobium and transition metals.
Dependencies are inferred from the claim text.