METHOD FOR PURIFYING POTASSIUM TANTALUM FLUORIDE

• Main Authors: NISHIMURA EIJI, SHINDO YUICHIRO, KUROKI MASAMI
• Format: Patent
• Language: English
• Published: 07.01.1992
• Edition: 5
• Subjects: CHEMISTRY; COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSESC01D OR C01F; INORGANIC CHEMISTRY; METALLURGY

PURPOSE:To readily obtain high-purity potassium tantalum fluoride with hardly any high-melting metals and radioactive elements by charging crude potassium tantalum fluoride into hydrofluoric acid, increasing the temperature, then adding a solution containing K<+> thereto, subsequently cooling the resultant mixture solution and separating a solid from a liquid. CONSTITUTION:Crude potassium tantalum fluoride is charged into hydrofluoric acid or a mixed acid containing the hydrofluoric acid and the resultant solution is then heated to 50-95 deg.C. A solution containing potassium ions is subsequently added to the solution and the mixture is then cooled to separate a solid from a liquid. The concentration of the hydrofluoric acid in the aforementioned solution is preferably >=25wt.%. This is because the potassium tantalum fluoride is hardly dissolved at a temperature thereof below ambient temperature if the concentration of the hydrofluoric acid in the above-mentioned solution is <25wt.%. Even if the temperature is then increased, the amount of the dissolved potassium tantalum fluoride is small. The amount of the potassium chloride used recrystallizing the potassium tantalum fluoride is 0.5-1.2 equiv. based on the theoretical value.