In order to utilise the powerful thermodynamic databases for process simulations, a concept called
Effective Equilibrium Reaction Zone (EERZ) was introduced to couple thermodynamic database
calculations and reaction kinetics. Using the EERZ concept, many process simulation models for
steelmaking processes have been developed within the FactSage steelmaking consortium. After
validation of the simulation results by comparing with plant data, the simulation models have been
applied to improve plant operations. Several success stories of the improvement of real steelmaking
operations are shared. A new user-friendly FactProSim software developed for building process
simulations is introduced.