An experimental study of direct reduction of hematite by lignite char

In this paper, the use of lignite char as the reductant is proved to be promising in direct reduction of iron (DRI) technology. A better understanding of the reducing characteristics of lignite char is necessary for the development of efficient DRI technologies. The application of lignite char as reductant in direct reduction of hematite has been investigated in this study, and the results are compared with those of lignite coal and graphite. Thermogravimetric analysis was used to analyze the thermal behavior of the composite pellets. Maximum iron oxide reduction rate occurred at 865, 829.5, and 920 °C when lignite coal, lignite char, and graphite were used as reductants, respectively, indicating that iron oxide can be reduced at lower temperatures in the presence of lignite char. X-ray diffraction analysis showed that complete reduction of hematite to elemental iron was achieved with lignite char after 15-min reduction at 1000 °C. Scanning electron microscopy-energy-dispersive X-ray analysis results showed that the atomic ratio of Fe/O was increased from 0.39 in pellets before reduction to 0.51, 0.55, and 0.71 after reduction by graphite, coal, and lignite char, indicating that lignite char reduced hematite to a higher degree compared to lignite coal and graphite.