Reaction-Mediator-based chlorination for the recycling of titanium metal scrap utilizing chloride waste

Abstract

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 FeCl x has drawbacks such as slow kinetics of Ti chlorination and high volatilization of FeCl x . 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 SmCl 3 in molten magnesium chloride (MgCl 2 ) can smoothly chlorinate Ti metal into gaseous titanium tetrachloride (TiCl 4 ), and the by-product SmCl 2 in the molten salt can be regenerated into SmCl 3 by FeCl 2 . Thus, SmCl 3 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 ef ficient and environmentally friendly.