Production Technology of Titanium by Kroll Process

Titanium sponge is industrially produced by the Kroll process. In order to understand the importance of the emerging smelting and recycling process, it is necessary to review the conventional production process of titanium. Therefore this paper provides a general overview of the conventional titanium manufacturing system mainly by the Kroll process. The Kroll process can be divided into four sub-processes as follows: (1) Chlorination of raw TiO2 with coke, by the fluidized bed chlorination or molten salt chlorination (2) Magnesium reduction of TiCl4 and vacuum distillation of MgCl2 and Mg by reverse U-type or I-type with reductiondistillation integrated retorts (3) Electrolysis process of MgCl2 by monopolar cells or multipolar cells to electrolyze into chlorine gas and Mg. (4) Crushing and melting process in which sponge titanium is crushed and then melted in a vacuum arc furnace or an electron beam furnace Although the apparatus and procedures have improved over the past 80 years, the Kroll process is the costly and time-consuming batch operation for the reduction of TiCl4 and the separation of MgCl2.