Hunter process

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The Hunter process was the first industrial process to produce pure ductile metallic titanium. It was invented in 1910 by Matthew A. Hunter, a chemist born in New Zealand, who worked in the US.

The process begins by preparing a mixture of rutile (a mineral consisting of titanium dioxide, TiO2) with chlorine (Cl2) and coke. The coke serves as a source of carbon which reacts with the oxygen (O2) in the TiO2 when extreme heat is applied, producing titanium tetrachloride (TiCl4) and carbon dioxide (CO2).

The titanium tetrachloride is reduced with sodium (Na) to form pure metallic titanium (99.9%) by heating TiCl4 with Na in a steel bomb at 700–800 °C. This final step is the actual Hunter process. It successfully produces very high quality titanium, but it was replaced in all but the most demanding applications by the more economical Kroll process in the 1940s.

TiO2(s) + 2Cl2 (g) + C (s) → TiCl4(l) + CO2 (g)
TiCl4(l) + 4Na(l) → 4NaCl(l) + Ti(s)