CALCULATION OF THE EFFECT OF OXIDES AGGLOMERATION IN LIQUID STEEL CONTAINING YTTRIUM

The behavior of nonmetallic inclusions in liquid steel results from such processes as fluctuation, adhesion and collisions between particles. In the metallurgical processes that take place in the ladle, the agglomeration based on turbulent collisions between oxide particles plays the most important role. Typically, the deoxidization of steel is conducted with the use of aluminum. Upon adding yttrium the process of oxides formation also refers to yttrium oxide (Y2O3). Both oxides have a strong grouping tendency. For this reason the collisions between particles will cover both oxides of the same and of different components. For the sake of determining the rate of turbulent collisions of aluminum oxide and yttrium oxide particles through the mixing of a hot metal bath, the Particle Grouping Method and population balance equation were used. The simulations were performed for the assumed mixing energy value for 6 exemplary size-groups. The initial number of particles, resulting from the deoxidization ability of Al and Y at given oxygen content and initial radius of the formed oxide, were assumed. The analysis of obtained results revealed that at a constant oxygen content, the increase of initial radius shortens the time of fading away of particles in all six size-groups. In the case of large inclusions, their grouping through collisions is faster; it results from the higher probability that particles of large radius will collide. Particles of a very small radius (1 pm) were observed to hardly agglomerate, and because of this were hard to remove from liquid steel.