Novel methods for the production of titanium

Abstract

Titanium ores are very plentiful in the earth crust but the demand for titanium metal is restricted by its high cost in spite of its excellent mechanical properties, corrosion and oxidation resistance and low density. Titanium was first produced by the Hunter process but this has been superseded, except for special applications, by the Kroll process which entails carbochlorination of rutile and ilmenite to obtain titanium tetrachloride followed by metallothermic reduction with magnesium. In the past ten years, ∼20 novel processes have been investigated as possible low cost routes for titanium, based upon electrolytic processes, both anodic and cathodic, and variations of the Hunter and Kroll processes. The anodic processes use a conducting anode consisting of Ti–O–C and the titanium is essentially electrorefined, in a molten salt, from the anode. The cathodic routes rely on either the electrodeposition of calcium or the electro-deoxidation of the oxide. The variations on the Hunter and Kroll processes include methods to convert these batch processes into continuous processes. Most of these new processes are at the laboratory or pilot plant stage and it will take several years before it is known whether one of them will replace the Kroll process. All users of titanium are watching these developments closely.