Simulation of primary-slag melting behavior in the cohesive zone of a blast furnace, considering the effect of Al2O3, FetO, and basicity in the sinter ore

The alumina content in the iron ore imported to Japan is increasing year by year, and some problems in blast furnace operation, due to the use of the high-alumina-containing sinter, have already been reported. In order to clarify the mechanism of the harmful effect of alumina on the blast furnace operation, the behavior of the primary melt, which is formed in the sinter at the cohesive zone of the blast furnace, has been simulated by dripping slag through an iron or oxide funnel. The effects of basicity, Al2O3, and FetO contents in the five slag systems on the dripping temperature and weight of slag remaining on the funnel have been discussed. It was found that the eutectic melt formed in the sinter would play an important role in the dripping behavior of the slag in the blast furnace through the fine poreosity of the reduced iron and ore particles. Al2O3 increased the weight of the slag remaining on the funnel, and its effect became very significant in the acidic and low-FetO-containing slag. It was estimated that the increase of the weight of the slag remaining on the funnel by Al2O3 in the ore could result in a harmful effect on the permeability resistance and an indirect reduction rate of the sinter in the blast furnace.