Effect of Na2B4O7 Addition on Carbothermic Reduction of Ilmenite Concentrate

Ilmenite concentrate is a superior quality raw material to production of titania slag. The iron oxide of ilmenite concentrate is reduced to metallic iron and titanium oxide enriched in slag. Therefore, the enhancement reduction of ilmenite concentrate is in favor of improving the level of smelting of titania slag and reducing smelting time and decreasing energy consumption. The effect of Na2B4O7 on the carbothermic reduction of ilmenite concentrate was investigated, and the addition levels were selected as 0%, 1%, 2%, 3% and 4%, respectively. It is concluded that, under the constant reduction conditions, the metallization and particle size of iron of reduced ilmenite concentrate showed an increase first and then a slightly decrease with increasing the content of Na2B4O7, while FeO and residual carbon showed an opposite tendency. Maximum metallization rate and the largest size of metallic iron were 89.5% and 113 µm at 2% Na2B4O7 content, respectively. FeO content was decreased from 11.58% to 4.23% and then increased to 5.81%, while residual C from 2.73% to 2.34% and then to 4.2%. The main phases of all the reduced samples were (Fe Mg)xTiyO5, Fe and TiO2. The TG and DTG curves indicated that the mass loss of ilmenite concentrate with Na2B4O7 addition was obviously more than that without Na2B4O7. Na2B4O7 can reduce the reduction temperature of ilmenite concentrate, and the extent of the temperature reduction was 80, 114, 111 and 119°C, respectively.