Carbothermic reduction behavior of FeS in the presence of CaO during microwave irradiation

Carbothermic reduction of FeS in the presence of CaO was experimentally studied by employing a multi-mode microwave generator at 1 050 W and 2.45 GHz as an external heat source to mitigate CO₂ and SO₂ emissions. According to XRD analysis, an ion exchange reaction between FeS and CaO was initiated at temperatures lower than 645°C and progressed by a further heating to 850°C without any evidence for the onset of a reduction reaction. Detection of Fe phase in the XRD pattern of sample heated to 920°C and existence of CO/CO₂ in the off-gas during microwave treatment demonstrated that the reduction reaction initiates at ca. 850°C. It was found that the onset of reduction reaction promotes the ion exchange reaction by FeO consumption via reduction to Fe. Moreover, optical microscope and SEM-EDX observations showed that carbon can be absorbed by metallic iron to make molten iron particles at 1 290°C.