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An off-line simulation model of the blast furnace hearth is developed based on mass balances for iron and slag, expression of the liquids outflow rates and logical conditions for the start and the end of the outflow of liquids. The dynamic model divides the furnace hearth into two regions of sizes that may change during the tapping process. It provides a description of the time evolution of the liquid levels and predicts the duration and the periods of iron-or slag-only flow in the beginning of the taps. The values of some model parameters are estimated on the basis of measurements in a reference blast furnace, while others are fixed. A sensitivity analysis of the model is provided, revealing the role of some key parameters. The model is demonstrated to describe the overall drainage behavior of the reference furnace reasonably well, and the presence of pools with different liquid levels can also be deduced from the real data. Finally, some recommendations for future work are suggested.

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A drainage model of a multi-taphole hearth of a (large) blast furnace operated by alternate tappings has been developed. The model, which is based on a simplified treatment of the pressure losses in the dead man, taphole entrance and taphole, can estimate the liquid levels and outflow rates of the two liquid phases in quasi-stationary and dynamic states. The sensitivity of the results to changes in the conditions, such as taphole length and diameter, dead-man porosity, as well as in the model parameters is illustrated. The effect of asymmetric conditions at the two tapholes, and dynamic responses of particular interest are also illustrated and discussed. The results of the model are finally compared with findings from a reference blast furnace where the outflows rates of iron and slag are routinely estimated, demonstrating that several of the typical outflow patterns observed in the furnace can be at least quantitatively reproduced. This demonstrates the feasibility of the model as a tool for gaining deeper insight into the complex drainage with alternating tappings and the evolution of the liquid levels in the hearth of large blast furnaces.