Numerical Study on Metal/Slag Drainage Rate Deviation during Blast Furnace Tapping

Remarkable deviation of metal fraction in the liquid drained out of blast furnace tap hole has been occasionally observed between the operated tap holes and/or tapping time stages. Introducing the concept of low permeability zone whose wall, due to the difference in two liquid phases' viscosity and/or wettabilitiy to coke particle, allows for metal to permeate freely but for slag not to permeate, the liquid drainage behaviors are examined by furnace hearth mathematical model simulations. The deviation of metal fraction between two operated tap holes is materialized under the hypothesis that furnace heath is divided into two sections by planar vertical low permeability wall (VLPW). While, the variation of time series change in liquid metal fraction during tapping operation is reproduced by hypothesizing the formation of cylindrical low permeability wall (CLPW) which concentrically parts the furnace hearth into center and peripheral area. Since the results of calculation for VLPW or CLPW formation indicate the notable raise of liquid level in furnace which could influence on abrupt increase of blowing pressure, the effectiveness of several operational optimization is assessed, resulting in suggestive conclusion that increasing the initial tap hole diameter is the most effective.