Rate of interfacial reaction between liquid iron oxide and CO-CO2

Abstract

The interfacial reaction rate between liquid iron oxide and CO-CO2 was determined using a thermogravimetric technique. The measured rates were controlled by the chemical reactions at the gas-slag interface. The apparent first-order rate constant, for the oxidation of liquid iron oxide by CO2, decreased sharply with the equilibrium CO2/CO ratio. The rate of reduction of liquid iron oxide by CO showed a slight increase with the oxidation state of the melt. At 1773 K, the apparent first-order rate constants are given by k=4.0×10−5(CO2/CO)−0.8 and k=4.0 × 10−5(CO2/CO)0.18 mol cm−2 s−1 atm−1 for the oxidation and reduction, respectively. The addition of basic oxides, such as BaO and CaO, resulted in an increased reaction rate, while the addition of acidic oxide, such as SiO2, decreased the rate. The results are consistent with the dissociation or formation of the CO2 molecule, involving the transfer of two charges, being the rate controlling mechanism of the reactions.