Oxidation Reaction of Silicon in Molten Iron of High Carbon Concentration by FeO Containing Slag

Abstract

The rate of oxidation reaction of silicon between Fe-4.4%C-Si melt and Li₂O-CaO-SiO₂-FeO slag has been investigated under the condition of mechanical stirring at 1 300°C. The initial concentrations of FeO in slag, (%FeO)₀, and silicon in metal, [%Si]₀, were 2.530 and 0.0080.1, respectively. The rotating speed of the stirrer was 50400 rpm.
The activity of silica, a_SiO2, in the slag has also been determined experimentally by measuring the concentration of Si in carbon saturated iron equilibrated with SiO₂ in Li₂O-CaO-SiO₂ slag at P_CO=1 atm and 1 300°C.
In the explored concentration range of FeO in the slag, the apparent metal-side mass transfer coefficient of Si, k'_si, increases with increasing (%FeO)₀, while k'_si does not change much with varying [%Si]₀. It is found that k'_si increases approximately in proportion to the 1/3 power of the rotating speed of the stirrer, but the effect of mechanical stirring on the mass transfer of FeO in the slag is negligible except at lower (%FeO). A mathematical model describing the simultaneous reactions of Si, C and FeO is developed. The reaction mechanism of the present slag-metal reactions is explained with the aid of the mathematical model.