Evaluation of the impact of the CO/C reducer on the CO₂ formation in the process of pyrometallurgical recovery of Fe from converter slag

Abstract The results of simulations of Fe recovery from steel slag containing iron oxides with C reducer dissolved in liquid slag and gaseous CO were presented in the paper. The simulations were performed with the use of a commercial program FactSage, and the calculations followed the procedure of dosing the reducer to slag in portions, each time reaching the state of thermodynamic equilibrium. The calculation procedure was realized sequentially, and the equilibrium composition of gaseous phase, nonmetallic phase and separated Fe was established at each calculation step. Gaseous products of CO and CO2 reduction were removed from the system with each successive calculation step. The simulation revealed that reaching comparable results of reduction requires using a considerable amount of CO. Moreover, the CO2 content in the gaseous phase and amount of separated Fe depend on the type of reducer. It was observed that the main mechanism was the reduction of iron with C. In this case the composition of gaseous products was mainly dominated by CO-CO2.