Abstract:Aiming at the problems that high Ca and Mg impurities ilmenite concentrate is difficult to meet the boiling chlorination process for preparing TiCl4, the preparation of TiCl4 from high Ca and Mg titanium raw material by carbothermic reduction - boiling chlorination was systematic studied from the perspective of thermodynamics and kinetics. The results show that the high-temperature carbon thermal reduction process of ilmenite concentrate involved the stepwise reduction process: FeTiO3 → TiO2+Fe → TinO2n—1(n=4—9)+Fe → Ti3O5+Fe → Ti2O3+Fe → TiCxO1—x+Fe. The temperature of carbon oxide titanium generation must be higher than 1 400 ℃. However, the impurity elements such as Ca, Mg, Al, Si, Mn in titanium concentrate will not be reduced to corresponding carbides within 1 800 ℃. In the process of carbothermic reduction of high Ca and Mg impurities ilmenite concentrate to prepare titanium oxycarbide, the weight loss rate increases in four stages with the increase of temperature. Among them, Stage 1 and Stage 3 are the rapid weight loss stages of metal Fe and carboxy-titanium controlled by diffusion, while Stage 2 and Stage 4 are the slow weight loss stages of metal Fe and carboxy-titanium nucleation and growth, respectively. The apparent activation energies of the four stages are 49.84, —2.24, 12.82, and —2.53 kJ/mol, respectively. During the boiling chlorination process, Fe, MgO, and CaO in the reduction products are preferentially chlorinated by chlorine gas, but when TiO2 is present, SiO2 and Al2O3 are not easily chlorinated. The most suitable temperature for boiling chlorination is 300—650 ℃. The first 5 min of boiling chlorination is the rapid chlorination stage of titanium oxycarbide in the reduction products, which is mainly controlled by the surface chemical reaction, and the next 5 to 20 min is the slow chlorination stage of Ti2O3, which is mainly affected by the internal diffusion control of the particles.