Carbon-Free Recovery Route for Pure Ti: CuTi-Alloy Electrorefining in a K-Free Molten Salt

Abstract

Metallic titanium is commonly produced by the carbon-dioxide-emitting Kroll process. The modern shift to sustainable technology has generated global interest in green processes. A carbon-free route for Ti manufacturing via the fabrication of a copper–titanium alloy and its electrorefining has been previously reported. This study focuses on the sustainability of the Ti-production electrorefining process (using a CuTi-alloy anode in LiF–NaF molten salt, with BaTiF6 addition, at 750 °C). BaTiF6, produced by a chemical reaction, was used as a K-free alternative to K2TiF6. The Ti-reduction mechanism and the anodic dissolution of Ti, CuTi, and Cu were investigated by potential sweep methods. Selective anodic dissolution of Ti, without Cu codissolution, occurred in a wide anodic potential range (−0.6 to 0.9 V vs W). Moreover, the Cu matrix remained on the anode, without sludge formation in the electrolyte, eliminating Ti-deposit recontamination by the anode material. Energy consumption and CO2 emissions were 1.66 times less than those of the Kroll process. The Ti-deposit morphology (with temperature, current density, and electrolysis-duration variation) was analyzed by scanning electron microscopy (SEM). Additional experimentation indicated that Ti can be electrochemically separated from Fe, confirming that low-grade TiO2 raw materials and off-grade Ti sponge could be used for the fabrication and processing of CuTi anodes.