Rate of reduction of iron oxide in iron and steelmaking slags by mass
contents of dissolved carbon (> 3%) in molten iron depends upon activi
ty of FeO, temperature, mixing of bulk slag and other experimental con
ditions. A general kinetic model is developed by considering mass tran
sfer of FeO in slag, chemical reaction at gas-metal interface and chem
ical reaction at gas-slag interface, respectively, as the three rate c
ontrolling steps. A critical analysis of the experimental data reporte
d in literature has been done. It is shown that in the case of slags c
ontaining mass contents of less than 5% FeO, the reduction of FeO is c
ontrolled by mass transfer of FeO in slag plus chemical reaction at ga
s-metal interface; when slags contain more than 40% FeO, the reduction
of FeO is controlled by chemical reaction at gas-metal interface plus
chemical reaction at gas-slag interface; at intermediate FeO mass con
tents (between approximately 5 and 40% FeO), the reduction of FeO is c
ontrolled by all three steps, namely, mass transfer of FeO in slag, ch
emical reaction at gas-metal interface and chemical reaction at gas-sl
ag interface. The temperature dependence of rate constant for the gas-
slag reaction is obtained as: In k2 = -32345.4(+/-6128)/T + 19.0(+/-3.
42);sigma(lnk2,1/T) = +/- 0.3. where k2 is expressed in mol m-2 s-1 ba
r-1. The mass transfer coefficient of iron oxide in bulk slag is found
to vary in the range 1.5 x 10(-5) to 5.0 x 10(-5) m/s, depending upon
the slag composition as well as experimental conditions.