On (%FeO)-[%C] Correlation During Primary Steelmaking

Endpoint carbon and temperature are the main targets for primary steelmakers. Final (%FeO) in slag can be correlated with this endpoint or target [%C]; lower [%C] leading to higher (%FeO). Turkdogan presented a correlation between these quantities in a nontrivial form: a clear trend was shown between (%FeO).[%C] and [%C]0.5. In this work, this correlation is revisited considering data collected from three steelmaking shops. A strong trend is observed between (%FeO).[%C] and [%C]0.5 for all the processes. However, the value of the product is much higher than that reported in the literature for [%C]<0.1. In order to interpret this trend, thermodynamic and mathematical analysis is performed. It is shown that, thermodynamically, the equilibrium [%C][%O] is closer to the [C]-[O]-CO reaction than the [C]-[O]-CO2 reaction. The strong linear trend likely reflects a combination of equilibrium effects and gas-steel-slag-kinetics.