The rate constant of CO
2 dissociation on the surfaes of CaO-SiO
2, CaO-Al
2O
3, CaO-SiO
2-CaF
2 and CaO-SiO
2-Fe
xO slags was measured by means of a
13CO
2-CO isotope exchange technique as functions of slag basicity, iron content, temprature and imposed equilibrium CO
2/CO ratio. It was shown that CaO-SiO
2-Fe
xO slags with low iron content and those with high iron content had different rate determining steps. According to those rate determining steps, the apparent rate constant,
ka, was calculated for each slag. Consequently, we obtained the equations:
ka=
k(1-Σ
iθi) and
ka=
k(1-Σ
iθi)(
aFeO2)
2(
PCO2/
PCO)
–1 for the former slag and the latter, respectively, where
k is the rate constant, θ
i is the fractional coverage of absorbed species
i. From the view point of dependence of the rate constant on oxygen partial pressure, these equations well represented the experimental results. For 35mass%CaO-65SiO
2 and 50mass%CaO-50Al
2O
3 slags, activation energies were estimated to be 203 [kJ/mol] and 120 [kJ/mol], respectively. Addition of CaF
2 up to 30mass% does not affect
ka for CaO-SiO
2 melts.
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