Ar-CO_2 混合ガスによる溶鉄の脱炭反応機構

概要

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A study has been made on the kinetics of the decarburization of liquid iron in Ar-CO_2 atmospheres at 1600℃. The study has been especially directed towards determining the rate-controlling steps at low carbon contents of the melt. In the concentration range above 0.02∿0.05%C__- (depending upon the partial pressure of CO_2), the rate of decarburization is influenced by the gas flow rate. On the other hand, in the concentration range below 0.02∿0.05%C__- (depending upon the partial pressure of CO_2), the rate of decarburization no longer depends on the gas flow rate, if it is higher than 1300 cc/min. The aspects on the mechanism of decarburization under the latter condition are summarized as follows ; (1) The decarburization by blowing gas of p_<CO_2> below∿0.1 is controlled by chemical reaction. The reactions conceived here are ; [chemical formula] The results can be explained reasonably by the model based on the simultaneous reactions except for the range where FeO is formed on the surface of melt. The rate constants obtained here are ; k_1′=(1∿2.5)×10^<-6> mol/cm^2sec atm^2, k_2=(2∿3)×10^<-5> mol/cm^2sec atm, k_3′=(3∿8.5)×10^<-6>mol/cm^2sec atm. (2) At p_<CO_2>≳0.1, the rate-determining factor changes gradually. It is shown that at p_<CO_2>≳0.2, the rate of decarburization is determined by the mass transfer of carbon in liquid iron, mass transfer coefficient k_C being 0.036 cm/sec.
1972-10-01