Determination of the Oxygen Content in the LiF-NaF-KF Melt

The present paper is dedicated to the quantitative determination of oxygen-containing impurities in the LiF-NaF-KF eutectic using electrochemical (cyclic and square-wave voltammetry) and reduction melting methods. The LiF-NaF-KF melt was analyzed before and after purifying electrolysis. The amount of oxygen-containing impurities removed from the salt during purification was determined. It was found that after electrolysis, the concentration of oxygen-containing impurities decreased by 7 times. The results obtained via electrochemical techniques and reduction melting were well-correlated, which made it possible to evaluate the quality of the LiF-NaF-KF F melt. To verify the analysis conditions, mechanical mixtures of LiF-NaF-KF containing Li2O were analyzed using the reduction melting method. The oxygen concentration in the mixtures varied from 0.672 to 2.554 wt. %. Based on the analysis results, the dependence approximated by the straight line was obtained. These data may be used to draw calibration curves and to further develop the procedure of oxygen analysis of fluoride melts.