Kinetics on the Hydrogen Reduction of FeO in Liquid Slag

摘要

The rate of reduction of liquid iron oxide with hydrogen was studied by using a thermobalance at 1673K. The sample charged in the shallow iron crucible was melted by SiC heater under inert atmosphere, and then reduced by impnging H_2-Ar, H_2-He or H_2-N_2 mixtures onto the surface of the melt through the stainless steel nozzle. The slag systems investigated were pure FeO, FeO-CaO, -TiO_2, -Al_2O-3 and -SiO_2, and the partial pressure of H_2 and the gas flowrate were varied in the ranges from 0.2 to 0.0003 atm and from 0.4 to 28 l/min, respectively. It was observed that the rate of hydrogne reduction of pure liquid FeO was governed by the gas phase mass trnasfer in the range of gas flowrate below 7 l/min with H_2-He mixture (Region 1) and was controlled both by the gas phase mass trnasfer and the interfacial chemical reaction (Region 2). The rate of chemcial reaction was estimated from the results of Region 2 by correcting the contribution of gas phase mass trnasfer to be 1.6x10~-6 (kg-oxygen/m~2 Pa). This value is about two order of magnitude higher than that of CO. The effect of additives on the chemcial reaction rate was estimated by combining the hydrogen reduction rate of pure liquid FeO observed in the present work with the composition dependence of CO reduction rate obtained in our previous work. Observed chemical reaction rates were in good accord with the estimated in the reduction of FeO-CaO and FeO-SiO_2 slags. Most of available literature data on the reduction rate of liquid FeO by solid carbon, hot metal and reducing gases were reviewed and compared with the results of the present work.