Characterisation of iron ore sinter and its behaviour during non-isothermal reduction conditions

Abstract

Egyptian iron ore sinter with low contents of barite (0·5 wt-%BaO) and alumina (0·7 wt-%Al2O3) was prepared by the down draft sinter pot technique and physically and chemically characterised. The sinter is mainly composed of unassimilated hematite, precipitated hematite and magnetite phases and glassy calcium silicate (slag). Manganese was concentrated in magnetite phase forming a solid solution of 'magnetite–jacobsite spinel'. Calcium ferrites were not detected in the sinter due to its low basicity (CaO/SiO2≈1). The sinter was non-isothermally reduced with carbon using a heating up reduction technique with the facility of following the high temperature phenomena during the reduction process. High temperature properties were determined from the results of X-ray observations, reduction rate profile and the gasification rate. The results obtained indicated that the reduction of sinter started at 823 K, then at >1073 K and the reduction rate increased due to the interaction between the carbon gasification and gaseous reduction processes. The retardation reduction, smelting reduction and meltdown of metallic iron phenomena occur at 1323, 1473 and 1680 K respectively, which simulate the high temperature region of the blast furnace for iron production.