Effect of FeO in dripping slag on blast furnace hearth drainage

Japanese iron and steelmaking industry has to reduce CO₂ emission by 10.5% in 2010 relative to the level of emissions in 1990. Stable blast furnace operation is required to reduce energy consumption and CO ₂ emission in iron and steelmaking industry. For the stable blast furnace operation, precise controlled drainage is one of the important factors. However, there are many unrevcalcd phenomena in the hearth to perform the stable operation. Therefore, in this work, the effect of iron and slag dripping pattern, FeO concentration in the dripping slag on the iron and slag surfaces, thermal properties of refractory and brick on drainage temperature, temperature distribution in the hearth, temporal variation of iron and slag drainage rates and interfaces shapes were investigated by using three-dimensional mathematical model. The results indicate that more than 2 mass% FeO in dripping slag will cause deterioration of slag drainage ability due to high slag viscosity around tapholes. Continuous monitoring of FeO concentration in the tapping slag is effective to prevent deterioration of slag drainage ability. The trends of the other side of tapping taphole temperature were varied dramatically according with FeO concentration in the dripping slag. Even in the case of 0 mass% FeO in the dripping slag, there is a solidified slag near the hearth wall except around the tapholes. A peripheral distribution pattern will result in a stable drainage. Slag, which dripped on near the other side of the tapping taphole, stays around the taphole, and does not drain from the tapping taphole located opposite side.