BOFdePhos – Control of Dephosphorisation in BOF process

Initial situation:

• End-point control of the Oxygen Steelmaking Converter (BOF) process is mainly based on results of a static charge calculation and observation of decarburisation based on off-gas data.
• Information on dephosphorisation behaviour and achievement of the final P target value is normally not available.  Thus quite often a reblow due to high P content, and also for steel temperature adjustment is required.

Working topics:

• Enhancement of existing dynamic converter models based on fundamental investigations of thermodynamic equilibrium conditions and mass flows determining the reaction kinetics, using appropriately extended thermo-dynamic data bases within ChemApp or FactSage and suitable CFD simulations.
• Trials with special sublance probes for on-line determination of the slag oxygen content.
• Development of model based dynamic control strategies for precise determination and optimal adjustment of the process end-point regarding phosphorus content and melt temperature, in order to achieve direct tapping after sublance measurement without waiting for steel probe analysis.

Results:

• Comprehensive dynamic model for the BOF process for on-line monitoring with focus on dephosphorisation, taking into account slag conditions and melt temperature.
• Accurate end-point determination with calculation of optimal set-points for oxygen blowing and slag former additions, to achieve the target values with higher resource efficiency.