2006 Volume 92 Issue 12 Pages 809-814
In order to examine the feasibility of the carbothermic reduction process using the composite pellets of iron ore and coal fines in their combustion packed bed, laboratory scale experiments were conducted. To prevent the reoxidation of the reduced pellets, attempts were made by coating the composite pellets with different fine materials such as iron ore, limestone, dolomite, serpentine and SiO2 reagent. The isothermal reduction experiment using a single composite pellet shows that SiO2 bearing material, such as serpentine fine and SiO2 reagent, give a reasonable suppression effect on the reoxidation at high temperature. The metallization degree of about 70% has been attained. On the basis of this result, the carbothermic reduction experiment in the combustion packed bed was conducted using the composite pellet coated with SiO2 reagent powder. In this case, the maximum metallization degree was as much as 45% because of the reoxidation of metallic iron could not be perfectly suppressed during the process. Further reduction experiment was carried out using the composite pellet coated by the fine mixture of CaO-SiO2-Al2O3 system to form a melt of the coating layer in high temperature. It gives the maximum metallization degree of about 60%. It suggests that the proposed carbothermic reduction process has a possibility to produce the partially-reduced iron burdens for the blast furnace, although its production rate is necessary to be improved.