Establishment of the Manufacturing Technology of 5N Super Purity Titanium Billets by Kroll Process

摘要

SUMITOMO TITANIUM CORPORATION has established the stable production of 5N grade titanium by the Kroll Process. To purify titanium tetrachloride (TiCl_4), a distillation column, which had higher performance than those currently in use, was installed. Magnesium was easy to become contaminated by nickel, only the magnesium that was obtained in the completely-nickel-free electrolytic cells was used as the reducing agent for the production of 5N titanium. In the reduction process of TiCl_4 by magnesium, the reaction retorts made exclusively for the 5N production with its lining covered by pure iron were used. By controlling the operating conditions appropriately, a mass of titanium sponge with extremely low impurities was produced. In the crushing process, only the central part of the sponge mass with the super purity was picked out by the guillotine press machine, then, was crushed into lumps of around 10-300 mm. The super purity titanium sponge lumps were formed into an electrode and were then melted under the right conditions using the exclusive mold. The forging machine was used to produce titanium billets. By taking these steps, the stable production of 5N grade titanium billets has been achieved.