Effect of off-centered silicon ladle on the removal strength of aluminum and calcium impurities

The bottom blowing gas in the silicon ladle plays an essential role in the purification of industrial silicon, and nozzle arrangement has an important effect on silicon quality after refinement. In the present study, a mathematical model has been proposed to assess the transient three-dimensional and two-phase flow in rich oxygen bottom-blowing silicon ladle with a single centered and off-centered porous nozzle, respectively. The numerical simulation is performed with the multiphase flow model of volume of fluid to model gas blown through a ladle. Fluid flow characteristics and the dead zone proportion between the centered and off-centered ladle are compared. The results demonstrate that the flow performance of liquid-silicon is better, agitation kinetics are more robust, and the dead zone area is smaller in bottom blowing of the off-centered ladle than of the centered ladle, which aligns well with the results of industrial experiments. The amount of Al and Ca impurities in silicon decreases by 13.22% and 25.87%, respectively, and the impurity distribution is more uniform.