2019 Volume 59 Issue 4 Pages 607-612
The minimum carbon requirement for ironmaking under carbon and hydrogen co-existing condition was discussed. The reaction system consisted of the reductions of iron oxides by carbon monoxide, hydrogen and solid carbon, the partial combustion of solid carbon, and melting of metallic iron and slag. The analysis took into account the equilibrium constrains for the reductions of the iron oxides and thermal requirement to produce hot metal and molten slag. The carbon requirement was plotted against the contributions of solid carbon, carbon monoxide and hydrogen to the FeO reduction. A valley (minimum route) of carbon requirement appeared from the C–CO reduction to the CO–H2 reduction condition on the ternary diagram, and the requirement got smaller with increase in H2 contribution. The carbon requirement decreased with lowering the temperature of FeO reduction. The effect of the water gas shift reaction was also analyzed. The water gas shift reaction (direction to generate CO2 and H2) decreased the carbon requirement due to its exothermic reaction heat.