1990 Volume 30 Issue 9 Pages 740-747
For the quantitative investigation of the desiliconization inside blast furnace by the iron oxide injection through tuyeres, fundamental researches on the desiliconization reaction by high FeO containing slag under pressurized and coke-coexisting condition were performed by the use of a pressurized high frequency furnace. Under coke-coexisting condition, FeO not only reacts with silicon in hot metal but also simultaneously reacts with coke through the direct reduction reaction and the decrease of temperature and the increase of total pressure accelerates the desiliconization reaction through suppression of the direct reduction reaction. The increase of the amount of slag and the increase of slag basicity result in the enhancement of the desiliconization.
Based on the results of fundamental researches, an unsteady state desiliconization mathematical model was developed with consideration of the coupled reactions of desiliconization and direct reduction and successively applied to the quantitative analysis of the coupled reactions.
A test operation with dry iron ore dust was performed under almost constant pig iron temperature at Wakayama No. 4 blast furnace. A decrease of silicon content of 0.09% was obtained by the iron ore injection rate of 32 kg/pt without carryover of the injected iron ore to the hearth. Accordingly, the desiliconization by the iron ore injection was verified in the commercial test operation.
