Carbochlorination of YOCl for Synthesis of YCl3

Abstract

As the production of high-quality titanium (Ti) metal increases significantly, the generation of low-quality Ti scraps increases and exceeds the demand for current cascade recycling in ferrous metallurgy. Therefore, the development of an upgrading recycling technology, in which scraps are refined and reutilized, is required. The magnesium (Mg) deoxidation assisted by the formation of oxychlorides of rare earth metals is currently considered a promising process for upgrading recycling technology, during which YOCl is formed as a byproduct. In this study, we investigate the synthesis and separation of YCl₃ from YOCl via carbochlorination at 973 and 1073 K and confirmed that YCl₃ can be regenerated from YOCl at a high conversion rate (82.7 pct at maximum). YCl₃ was also formed even in the presence of MgCl₂; however, MgCl₂ decreased the conversion rate (49.8 pct at minimum). The conversion rate in the temperature region where YCl₃ is a liquid (1073 K) was lower than that in the temperature region where YCl₃ is a solid (973 K). Therefore, an operation with temperature cycling, in which YCl₃ is formed at a temperature where YCl₃ is a solid and then the temperature is increased to a temperature where YCl₃ is a liquid to drain the molten mixed salt, is efficient.