Kinetics of the reaction of SiO(g) with carbon saturated iron

Abstract

The reaction of SiO(g) with carbon saturated iron plays an important role in silicon transfer in the iron blast furnace. In the tuyere zone SiO(g) is generated from the reaction of coke with its ash, and the SiO(g) reacts with carbon saturated iron droplets as they pass through the furnace. This reaction may also play a role as a gaseous intermediate reaction for the reduction of SiO₂ from slags by carbon dissolved in iron. The rate and controlling mechanism for the SiO reaction with carbon dissolved in liquid iron was determined in the temperature range 1823 to 1923 K. A constant pressure of SiO(g) was generated by the reaction of CO with SiO₂; the reaction of carbon with SiO₂ gave higher but decreasing pressures of SiO with time. The SiO(g) generated was then reacted with carbon saturated iron under conditions for which the gas phase mass transfer conditions are clearly defined. By a systematic variation of the appropriate variables it was demonstrated that the rate was controlled by gas phase transfer of SiO to the gas-metal interface. The rate changed with gas diffusional distance but was not a strong function of temperature or of melt composition. The rate calculated for gas phase mass transfer was in good agreement with the experimental results.