• Pownceby, Mark
• Manuel, James
• Webster, Nathan
• Madsen, Ian
• Scarlett, Nicola

Abstract

The reaction sequences involved in the formation of iron ore sinter phases were determined using in situ synchrotron-based X-ray diffraction. Experiments were carried out using a synthetic sinter mixture containing 77.36% Fe2O3, 14.08% CaO, 3.56% SiO2 and 5.00% Al2O3 corresponding to a basicity of ~4. The alumina content represents the upper level of alumina concentrations measured in phases formed in industrially produced plant sinter. Data were collected during heating of the sampleto 1350 degC under an atmosphere of 0.5% O2 in N2, equivalent to an oxygen partial pressure of 5x10-3 atm. This temperature was sufficient to ensure melting. Data were also collected on cooling of the sample back to room temperature to examine recrystallisation of phases from the melt.Results showed the sequence of reactions initially involved the formation of calcium ferrite phases C2F and CF. These subsequently reacted with the silica and hematite leading to the solid state formation of SFCA and SFCA-1. SFCA and SFCA-1 were the last phases to form in the system and were both stable up to ~1260 degC. Above ~1260 degC, melting of the SFCA phases and reduction of the remaining hematite occurred producing the assemblage magnetite+melt.During cooling, both SFCA phase types recrystallised from the melt initially coexisting with magnetite until secondary hematite formed. This is the first study to demonstrate that both SFCA and SFCA-1 are precipitated from the melt during cooling of iron ore sinter. Future work will extend the range of compositions studied to examine the effect of basicity and alumina concentration on the phase assemblages as a function of temperature and oxygen partial pressure.

Topics

• impedance spectroscopy
• x-ray diffraction
• experiment
• Oxygen
• melt
• iron
• Calcium
• sintering