Revolutionizing titanium production: A comprehensive review of thermochemical and molten salt electrolysis processes

Titanium exhibits outstanding properties, particularly, high specific strength and resistance to both high and low temperatures, earning it a reputation as the metal of the future. However, because of the highly reactive nature of titanium, metallic titanium production involves extensive procedures and high costs. Considering its advantages and limitations, the European Union has classified titanium metal as a critical raw material (CRM) of low category. The Kroll process is predominantly used to produce titanium; however, molten salt electrolysis (MSE) is currently being explored for producing metallic titanium at a low cost. Since 2000, electrolytic titanium production has undergone a wave of technological advancements. However, because of the intermediate and disproportionation reactions in the electrolytic titanium production process, the process efficiency and titanium purity according to industrial standards could not be achieved. Consequently, metallic titanium production has gradually diversified into employing technologies such as thermal reduction, MSE, and titanium alloy preparation. This study provides a comprehensive review of research advances in titanium metal preparation technologies over the past two decades, highlighting the challenges faced by the existing methods and proposing potential solutions. It offers useful insights into the development of low-cost titanium preparation technologies.