Rate of Interfacial Reaction Between Liquid Iron Oxide and CO-CO_2

摘要

(1) Highly accurate, direct measurements of the gas (CO-CO_2) - slag (containing Fe_xO) reaction rate were accomplished by using a gravimetric technique. The rates measured in this study were controlled by the gas-slag interfacial reaction. (2) The apparent rate constants of the interfacial reactions between liquid iron oxide and CO and CO_2 gases at 1773 K, were given by k_(red) = 4.08 x 10~(-5) (P_(CO_2)/P_(CO))~(0.18) mol-O cm~(-2) s~(-1) atm~(-1) for the reduction and, k_(oxi.) = 3.86 x 10~(-5) (P_(CO_2)/P_(CO))~(-0.80) mol-O cm~(-2) s~(-1) atm~(-1) for the oxidation. (3) The apparent rate constant for liquid iron oxide, in equilibrium with solid iron at 1673 K, was 1.8 x10~(-5) mol-O.cm~(-2).s~(-1).atm~(-1), slightly higher than 1.13x10~(-5) mol-O cm~(-2) s~(-1) atm~(-1) obtained by Nagasaki from similar experiments. At 1673 K, the reduction rate constants for liquid iron oxide showed the same dependence on the slag oxidation state as that at 1773 K. They were given by k_(red) = 2.29x10~(-5)(P_(CO_2)/P_(CO))~(0.18) mol-O cm~(-2) s~(-1) atm~(-1) (4) Results similar to those on liquid iron oxide were obtained for the reduction and oxidation of alumina-saturated iron aluminate by CO and CO_2 gases, with an 18% decrease in the apparent rate constant at 1773 K. (5) The results for binary slag systems containing iron oxide indicate that the addition of basic oxides to iron oxide significantly increased the rate, whereas the addition of acidic oxides decreased the rate. (6) The 'charge transfer' mechanism was proposed to be the dominating mechanism of the reaction with minor effect from the 'site blockage'.