Improving the Slag-metal Separation of a Blast Furnace Trough with the Use of Numerical Simulations

During slag granulation, after metal separation in the blast furnace main runner, the contact between water and slag can lead to explosions due to the presence of metal in the slag. This study aims to reduce the amount of molten metal passing through the slag port of a main runner in a Brazilian steel mill. With this goal, multiphase numerical modeling simulations were performed for different configurations of the main runner. A VOF (Volume of Fluid) model was used to represent the interactions between the fluids (molten metal, slag and air), coupled with a DPM (Discrete Particle Model) to represent metal particles coming from the blast furnace. The metal separation was analyzed by measuring the amount of metal, both fluid and particle, which exits the slag port. The impact of increasing the width and the depth of the main runner, as well as the slag thickness of the slag on metal separation were analyzed. Simulation results show that the width increase reduces the metal passage through the slag port, while increasing the depth of the runner can jeopardize the slag separation, due to higher wave velocities. Thicker slag was also found to positively influence fluid separation. However, a certain minimum thickness was found to be necessary to observe this improvement.