1. Technology-EngineeringThe Kroll process is a pyrometallurgical industrial process used to produce metallic titanium from titanium tetrachloride. As of 2001 William Justin Kroll's process replaced the Hunter process for almost all commercial production. == Process == In the Kroll process, titanium tetrachloride is reduced by liquid magnesium to give titanium metal: TiCl4+2Mg→825 A∘CTi+2MgCl2 The reduction is conducted at 800–850 °C in a stainless steel retort. Complications result from partial reduction of the TiCl4, giving to the lower chlorides TiCl2 and TiCl3. The MgCl2 can be further refined back to magnesium. === Appurtenant processes === The resulting porous metallic titanium sponge is purified by leaching or vacuum distillation. The sponge is crushed, and pressed before it is melted in a consumable electrode vacuum arc furnace, "backfilled with pure gettered argon of a pressure high enough to avoid a glow discharge". The melted ingot is allowed to solidify under vacuum. It is often remelted to remove... from wikipedia.org