Abstract
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.
Highlights
THE blast furnace is the primary unit in the production chain where iron ores are processed to liquid iron before the conversion into steel
The geometric parameters, production rate, slag ratio and blast pressure were estimated from typical values of large blast furnaces, and the material properties from values used in similar numerical studies of the blast furnace hearth in the literature
The arising model has been illustrated by a set of examples, where the sensitivity of the simulated liquid levels and outflows is studied with respect to changes in the conditions and to some model parameters
Summary
THE blast furnace is the primary unit in the production chain where iron ores are processed to liquid iron before the conversion into steel. The fact that the iron-slag interface may descend well below the taphole was first pointed out and demonstrated in laboratory scale in Australia by Tanzil and co-workers.[3] The findings partly revised the earlier results on slag drainage presented by Fukutake and Okabe.[5,6] The work in Australia was continued by Zulli,[7] who refined the expressions of the residual slag by considering the motion of both interfaces These findings were used in a model by Nightingale et al for estimating the coke-bed voidage in operating blast furnaces.[8] Opberger and Toxopeus[9] developed a simplified hearth drainage model inspired by findings in industrial furnaces, assuming a full mixing of the two phases in the taphole, using average liquid properties to estimate the pressure drop.
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