低炭素領域における溶鉄の脱炭反応機構

抄録

The present paper deals with a kinetic study of decarburization of liquid Fe-Ca lloy in CO-CO₂ atmospheres at 1 600°C. The study has been especially directed towards determining the rate-controlling steps at low carbon contents of the melt.
In the concentration range above 0.05%C, the rate of decarburization is influenced by the gas flow rate.
It is shown that at carbon content higher than 0.1-0.15%, the decarburization controlled by gaseous diffusion.
In the concentration range below 0.05%C, the rate of decarburization no longer depends on the gas flow rate, if it is higher than 1 300cc/min. The views on the mechanism of decarburization under this condition are summarized as follows;
(1) The decarburization by blowing gas of the ratio pco, /pco below 1/4 is controlled by chemical reaction.
The rcactions conceived here are;C+CO₂k₁→k_1′2CO₃, CO₂k₂→k_2′CO+O, C+Ok₃→k_3′The results can be explained reasonably well by postulating appropriate values for k₂, k_3′, k_1′/_k3′.
(2) At higher gas ratio (Pco₂/Pco≥1/4), the rate-determining factor changes gradually.It is shown that at pco₂, /pco≥7/3, the decarburization is controlled by the mass transfer of carbon in liquid iron, themass transfer coefficient being 0.036cm/sec.