Electrorefining of Titanium in Alkali Metals Chloride-Fluoride Melts With and Without Additives of Magnesium Fluoride

Titanium powders were obtained by the electrorefining in the NaCl-KCl-NaF(10 wt %)–KTiF(7 wt%)–Ti melt with and without magnesium fluoride (MgF) addition. The influence of temperature and the cathodic current density on the current efficiency was determined. It was found that the current efficiency of the titanium electrorefining in the chloride-fluoride melt increased with the introduction of Mg cations into the melt. The powders granulometric analysis of titanium powders obtained in melts of various compositions showed that the dispersion of powders decreased when highly polarizing cations were introduced into the melt. The electrolysis parameters and the temperature effect on the purity of obtained powders in chloride-fluoride melts of various compositions has been studied. It was determined that upon the titanium electrorefining in the chloride-fluoride NaCl-KCl-NaF-KTiF-Ti melt, the content of impurities in the metal decreased, and a lower impurities content was found in titanium powders obtained in the melt with the addition of magnesium fluoride. A comparative analysis of the electrorefining in the chloride-fluoride melt with the addition of magnesium fluoride (NaCl-KCl-NaF-KTiF-Ti-MgF) has shown the advantages of this melt in comparison with a molten salt system that does not contain the magnesium salt. These advantages are due to the higher current efficiency, the less dispersion of powders, and the lower content of impurities in the metal. As a result of the work, the optimal electrolyte composition (NaCl-KCl-NaF(10 wt %)–KTiF(7 wt %)–Ti-MgF(1.4 wt %)) and the parameters of the electrorefining process (i = 100 mA/cm; T = 1023-1073 K) were determined. Under these conditions the titanium powder of 99.73% purity was obtained.