Thermodynamic Study on Production of Fe-Si-Ca Master Alloy Using Modified Molten Converter Slag

The thermodynamic behavior and the effects of energy saving in the production of Fe-Si-Ca master alloy from modified molten converter slag using SiO2 as a modifier were investigated by thermodynamic analysis with different additions of the modifier and reductant at various temperatures to fully recycle the physical sensible heat and valuable elements in the metallurgical slag. The results showed that the activity of SiO2 in the slag increased rapidly with the w(SiO2) increase from 40 wt.% to 60 wt.%, but the activity of CaO was low and decreased slightly with the w(SiO2) increase. When the w(SiO2) in the slag was 60 wt.% with an external addition of 35 wt.% of reductant at 1800 °C, the reduction ratios of silicon and calcium reached 90.05 mass % and 52.87 mass %, respectively, and the w[Si] and w[Ca] in the master alloy were 51.60 wt.% and 17.67 wt.%, respectively, resulting in an energy saving of 805.6 kWh per ton of produced ferroalloys.DOI: http://dx.doi.org/10.5755/j01.ms.21.4.9559