Dephosphorisation of high phosphorus oolitic hematite by carbon composite pre-reduction and fast melting separation

Abstract

High phosphorus oolitic hematite deposit is a kind of refractory iron ore resource of huge amount. At present, it is difficult to be utilised by traditional physical and chemical technology efficiently and economically. A novel process for utilisation of the high phosphorus oolitic hematite based on carbon composite pre-reduction and fast melting separation has been put forward in the paper. High grade pig iron nugget of low phosphorus could be obtained in the present research. The influence of experimental conditions, such as pre-reduction temperature, C/O (molar ratio) and basicity, on the dephosphorisation behaviours was studied in detail. The thermodynamic basis and reduction and melting separation process were also analysed. The phosphorus content in the iron nugget decreased with the increasing of basicity and increased with the increasing of C/O. The optimum parameters were pre-reduction temperature of 1200°C for 30 min, C/O of 0.95 and basicity of 1.7. After melting separation of molten iron and slag at 1400°C for 10 min, the iron nugget containing 0.02 wt-% [P] would be obtained. The dephosphorisation degree and iron yield in the form of iron nugget were 97.5% and 96.9% respectively. The iron nugget may be directly used as the raw materials of steelmaking from the view point of its high grade.