Reaction-Mediator-Based Chlorination for the Recycling of Titanium Metal Scrap Utilizing Chloride Waste

In this study, a novel chlorination technique for metallic titanium (Ti) was devised in order to establish a recycling process that uses both Ti metal scrap and iron chloride (FeClx) waste, and its feasibility was demonstrated. Direct reaction between Ti and FeClx has drawbacks such as slow kinetics of Ti chlorination and high volatilization of FeClx. To overcome these, the authors proposed a chlorination technique utilizing a reaction mediator in molten salt. Based on thermodynamic analyses of lanthanoid chlorides, some fundamental experiments were carried out with samarium trichloride (SmCl3) as a reaction mediator. It was experimentally demonstrated that SmCl3 in molten magnesium chloride (MgCl2) can smoothly chlorinate Ti metal into gaseous titanium tetrachloride (TiCl4), and the by-product SmCl2 in the molten salt can be regenerated into SmCl3 by FeCl2. Thus, SmCl3 in a molten salt works efficiently as a reaction mediator, and the newly proposed chlorination technique has the potential to make the Ti recycling process more efficient and environmentally friendly. [doi:10.2320/matertrans.M-M2014838]