Production of Low-SiO2 Iron Ore Sinter and Blast Furnace Operation at Kobe Works, Kobe Steel, Ltd.

Sintering technology that lowers the SiO2 content from 5.6% down to 4.9% has been achieved at Kobe Works on the basis of the following concept: the desirable structure of quasi-particles for low-SiO2 sinter consists of limonite ores as the nucleus and fine ores with low SiO2 and Al2O3 contents as adhering particles. In addition, the basicity and MgO content of sinter should be increased. As a result, the reducibility and high-temperature properties of sinter have been improved, though the RDI value of sinter increased. The use of low-SiO2 sinter in the Kobe No. 3 Blast Furnace has brought about the increase in overall permeability due to an increase in permeability at the lower part of the furnace, in spite of a decrease in the upper part. This increase has contributed to an appreciable increase in the ore/coke ratio and rate of pulverized coal injection.