溶鋼再酸化に及ぼす撹拌およびスラグ条件の影響

概要

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The kinetics of reoxidation mechanism with slag in Al killed steel were investigated in laboratory experiments at 1873K in MgO crucibles with 10kg steel. The CaO-SiO_2-Al_2O_3-FeO-MnO slags were used to study the effect of (FeO+MnO), slag volume, W_s and stirring gas flow rate, Q on [sol.Al] reoxidation rate. Experimental results were evaluated by a coupled reaction model. Apparent rate constants of [sol.Al], α_<Al> increased with increase of (FeO+MnO) and W_s. Mass transfer coefficients in metal, slag and reaction rate coefficient for reduction of SiO_2 were estimated to be 2.5×10^<-6>-6.0×10^<-6>(m/s), 1.0×10^<-5>-2.5×10^<-5>(m/s) and 3.2×10^<-3>(kg/m^2・s), respectively. Mass transfer coefficients in metal, k_m obtained by parameter fitting method under the various conditions of Q showed k_m∝U^<1.5>, where U is mean surface velocity calculated using two dimensional flow analysis. This relationship was also obtained from turbulent flow model under the assumption that friction velocity has linearity with surface velocity. Calculated [sol.Al] in 250t ladle showed a good agreement with observed one during killing before casting. Calculated results showed that [sol.Al] in the ladle rapidly decreased in the last period during casting because slag volume ratio to molten steel increased during casting.
社団法人日本鉄鋼協会の論文
1998-05-01