Solid-State Reduction of Chromite Concentrate - Melting of Prereduced Chromite

The solid state reduction of a chromite concentrate from Northern Greece in the temperature range 1100-1470 degrees C has been studied. The degree of reduction of chromite by graphite was found to increase with increasing temperature, time, and carbon addition. The maximum reduction percentage attained (defined as the mass of carbon monoxide evolved expressed as a percentage of the carbon monoxide that would be evolved if the reduction was complete) was 75%. The maximum metallisation of iron and chromium was 91 and 67%, respectively. The main reduction products were: (i) metallic products, in order of succession of formation, Fe-C alloy, (Cr,Fe)(7)C-3, and (Cr,Fe)(23)C-6 and (ii) non-metallic products, spinels rich in MgO and Al2O3 that contain chromium in the divalent state and forsterite. Melting of chromite, prereduced to 72.5% reduction, at 1550 degrees C for 1.5 h led to 97.5% chromium recovery and 100% iron recovery. Satisfactory silicon and carbon contents of the metallic products were attained. Ironmaking & Steelmaking