Phase Diagrams of the Systems KCl–KF–K₃VF₆ and NaCl–NaF–Na₃VF₆

抄録

In order to determine suitable electrolytes for the electrorefining of vanadium or electro-extraction from soluble anodes, the freezing points of the following systems were measured by thermal analysis: KCl–VF₃ (up to 25 mol%), NaCl–VF₃ (up to 45 mol%), NaCl–KCl(equimolar)–VF₃ (up to 25 mol%), KCl–KF–K₃VF₆, and NaCl–NaF–Na₃VF₆. The phase equilibrium relations in these systems were also examined by X-ray diffraction analysis. It was found that the system KCl–KF–K₃VF₆ is a ternary eutectic type and has its ternary eutectic point at 594°C and KCl 54.8, KF 44, K₃VF₆ 1.2 mol%. It was also found that the system NaCl–NaF–Na₃VF₆ is a ternary eutectic type and has its ternary eutectic point at 661°C and NaCl 24.3, NaF 70, Na₃VF₆ 5.7 mol%.