Alternative route for magnetite processing for lower carbon footprint iron-making through lime-magnetite pellets containing CaFe3O5

Magnetite is relatively harder to reduce compared to hematite and present practise of magnetite processing involves its oxidation to hematite during pelletisation, followed by subsequent reduction in the blast furnace. In this paper, we establish the feasibility of forming a reducible CaFe3O5 (CWF) phase through the addition of lime to magnetite that can be directly charged to iron-making units. This new approach will potentially provide a better process route (in terms of CO2 emissions) for the production of iron. Thermodynamic assessment was carried out to understand the suitable range of temperature, composition and oxygen partial pressure for CWF stability. Experiments were carried out using laboratory grade chemicals and products were characterised using XRD, SEM and EDX. Reducibility of CWF phase was measured using scaled-down standardised tests and was found to be comparable to industrial sinters. Compressive strength of the CWF pellets was in the range of 14 to 35 MPa.