Purification of Lithium Chloride-Potassium Chloride Eutectic

Lithium chloride-potassium chloride eutectic is the most commonly used electrolyte in electrorefining dry reprocessing, and its impurities directly affect current efficiency and product purity. In this study, high-temperature calcination, HCl gas bubbling, and potentialstat electrolysis were used to remove the volatile, oxygen ions, and metal ions impurity in molten salt in sequence, and to obtain higher purity molten salt. Thermogravimetric analysis (TGA), electrochemical and inductively coupled plasma atomic emission spectrometry (ICP-AES) were used to compare the contents of impurities in molten salt before and after purification. The results show that the optimal calcining temperature range for removal of volatile impurities is 450-650 ℃; the optimal electrolytic potential for removing metal ions impurity is -2.3 V vs. Ag/AgCl(x=2%), and the total metal ion concentration after constant potential electrolysis for 800 s is less than 1.5×10^-6 g/g (salt). Based on the above results, higher purity LiCl-KCl eutectic can be obtained by high-temperature calcination, HCl gas bubbling, and constant potential electrolysis.