Research on the Recovery of Secondary Iron-Bearing Dust in Direct Reduction of Carbon Composite Pellets

Abstract

In order to recover secondary iron-bearing dust, with converter sludge, mill scale, gravitational ash, casthouse ash as raw materials, high basicity carbon composite pellets are prepared to make iron nuggets through self-reduction at high temperature. The study demonstrates that: The effectively separation of iron and slag, naturally pulverization of the slag phase, and good surface quality of bigger, glosser and brighter iron nuggets can be obtained with reduction temperature 1400 °C,C/O molar ratio 1.1,as well as basicity above 1.8 in this process; The iron phase is not generated well and proportion of small size iron nuggets increases when C/O molar ratio is increased; With C/O molar ratio increases or temperature rises, CO generated increases in direct reduction, which strengthen the reducibility atmosphere in the pellets, beneficial to the processing of desulfuration and dephosphorization; Rising temperature accelerates the generation of molten iron, so that, the fixed carbon contacts with the molten iron longer, which increasing the carbon in iron nuggets. More carbon is provided for the carburizing reaction for the sake of increasing C/O molar ratio, as a result of making more carbon in iron nuggets.