What role does titanium tetrachloride play in titanium production?

Titanium tetrachloride (${\text{TiCl}}_4$) is a critical intermediate in the production of titanium metal, serving as the primary precursor for the extraction process. Its role involves several key stages:12

• Production: Titanium-bearing ores, such as ilmenite or rutile, are treated with carbon and chlorine in a carbo-chlorination process to yield ${\text{TiCl}}_4$. This raw product undergoes rigorous purification, typically through fractional distillation, to remove impurities like vanadium oxychloride and ferric chloride, ensuring a purity level exceeding 99.9 percent.12
• Reduction: To obtain metallic titanium, the purified ${\text{TiCl}}_4$ is reduced using either sodium (the Hunter process) or magnesium (the Kroll process). These reactions occur in sealed vessels under an inert argon atmosphere to prevent contamination.32
• Result: These reduction processes produce titanium in the form of a highly porous material known as "sponge," which is subsequently processed into ingots.32

Additionally, ${\text{TiCl}}_4$ is essential to the titanium pigment industry, where it is reoxidized to produce titanium dioxide (${\text{TiO}}_2$).13