Integrated Mathematical Model for Nitrogen Control in Oxygen Steelmaking Process

The control of nitrogen content in liquid steel becomes an important issue for future REF (Reducing Electric Furnace)-BOF (Basic Oxygen Furnace) process to produce ultra-clean steel. In this study, an integrated model to predict nitrogen in a full-scale BOF process was developed. The present model can calculate nitrogen removal and pickup in the different reaction zones including slag-metal-gas emulsion, hotspot, and Ar/N2 bubbles depending on static inputs such as composition and temperature of hot metal and scrap, and dynamic process parameters namely lance height, oxygen flow rate, and bottom stirring gas flow rate during BOF operation. Data from a 330-ton industrial BOF operation at Tata Steel Netherlands were used for the model validation. The present model was applied to the calculation of nitrogen concentration profiles in the BOF process depending on various future operation scenarios pertaining to the decarbonization of the steelmaking process.