Flow patterns of iron and slag in the blast furnace taphole

The drainage of molten iron and slag is of considerable significance for the ironmaking blast furnace (BF). The draining process is in principle driven by the in-furnace overpressure that balances the pressure drops induced by liquid flows through the dead man and taphole. The two-liquid flow in the taphole has not received much attention, even though some investigators have mentioned the key role of taphole operation in BF drainage. In this paper, the taphole flow pattern, i.e., separated or dispersed flow, is predicted by utilizing a model of zero real characteristic which is based on the stability analysis of two immiscible liquids flowing through an upwards inclined tube. The model is firstly validated by comparison with a set of physical modeling results from the open literature and the experimental system is believed to represent that of an industrial BF taphole, according to similarity laws. Simulations with the model are applied to demonstrate how different factors affect the taphole flow pattern. In a more detailed application short-term tapping data from the commercial BF is evaluated by the model. The calculated results show that separated flow of iron and slag is more likely to occur in the taphole of the studied BF.