7TH EUROPEAN COKE AND IRONMAKING CONGRESS - ECIC 2016

Depletion of high-quality hematite ore stimulates an increase in the utilization of magnetite ore in ironmaking. Reduction of magnetite ore pellets was studied in a fixed-bed reactor at different temperatures and gas compositions. The effect of temperature on the magnetite ore reduction was studied at 700 – 900 °C by CO/CO2 gas mixture with 80 vol pct CO. The effect of gas composition was examined at 750 oC using CO/CO2 gas mixture with CO content 60 – 85 vol pct; and at 800 °C using CO/CO2/H2 gas mixture with H2 content 5 – 25 vol pct and fixed CO/CO2 ratio of 80/20. Phase development in the process of the ore reduction was studied in-situ using High-Temperature XRD (HT-XRD) analysis. In the HTXRD reactor, magnetite ore was reduced by CO/CO2 gas mixture (80 vol pct CO) at 750 °C with measurements of XRD patterns along the reduction course. Phase development in the process of reduction was derived using Rietveld refinement of the HT-XRD spectra. Carbon concentration in iron was found from the lattice parameters of γ-Fe formed during reduction. Swelling of magnetite ore was observed in the process of reduction by CO/CO2 and CO/CO2/H2 gas mixtures, which was attributed to carbon dissolution in γ-Fe and bubbles’ formation. Swelling index increased with increasing CO/CO2 ratio and decreased with temperature. In the reduction of magnetite ore by CO/CO2/H2 gas mixtures, swelling decreased with H2 addition.