The rate of silicon oxidation between Fe-4.4% C-Si alloy and Li₂O-CaO-SiO₂-FeO slag has been investigated under the condition of mechanical stirring at 1300°C. The initial concentrations of FeO in the slag, (%FeO)₀, and of silicon in the metal, [%Si]₀, were 2.5-30 and 0.008-0.1, respectively. The rotating speed of stirrer was 50-400rpm. The activity of SiO₂, a_SiO2, in the slag has also been determined experimentally by measuring the concentration of silicon in carbon saturated iron equilibrated with SiO₂ in the Li₂O-CaO-SiO₂ slag at P_CO=1 atm and 1300°C.
Under the experimental conditions adopted, the apparent mass transfer coefficient in the metal phase, 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 stirrer. However, the effect of mechanical stirring on the mass transfer of FeO in the slag is negligible except at low (%FeO). A mathematical model describing the simultaneous reactions of silicon, carbon and FeO is proposed. The reaction mechanism of the slag-metal reactions is explained with the aid of the mathematical model proposed.