Effects of Na2CO3 on reduction mechanism and kinetics of iron during deep reduction of ilmenite concentrate

High-quality upgraded titanium slag obtained through semi-molten reduction with the addition of Na2CO3 is important for the fluidizing chlorination process to produce TiO2 pigments. The key is the effect of Na2CO3 on the reduction behavior of iron. Therefore, the effects of Na2CO3 on reduction mechanism and kinetics of iron during deep reduction of ilmenite concentrate were studied. The results indicated that the metallization ratio of the reduced sample increased with increasing temperature, time, and dose of Na2CO3. The addition of Na2CO3 significantly accelerated the reduction of iron in the ilmenite concentrate and promoted the growth of iron particles. However, the addition of Na2CO3 produced sodium iron titanates; thus, the metallization ratio of the sample decreased with an increase in the temperature and time when the temperature was above 1200 °C and the time was more than 30 min. When the doses of Na2CO3 were 0, 3, and 6 wt.%, the reduction of iron was controlled by the interfacial chemical reaction, both the interfacial chemical reaction and diffusion, and diffusion, respectively, and the apparent activation energies were 134.91, 64.89, and 120.82 kJ/mol, respectively.