Theoretical study on the separation of inclusion particles by pinch force from liquid steel flowing in a circular pipe

The pinch force which is one of the most general electromagnetic forces in the metallurgical field can be generated by impressing an electrical current in a liquid metal. In this force field, electrically nonconductive particles suspended in a liquid metal will receive a force in the opposite direction to the pinch force, and be squeezed out from the liquid metal. In the present study, this principle was applied to the separation of nonmetallic inclusion particles from liquid steel. The separation efficiency η of inclusion particles from a circular pipe flow of liquid steel was thought to be a function of the following nondimensional parameters: V_R(= V_Pt/W_m), C₁(= μ_eI_rms²/ρv²), D_R(= d_p/2r₁), Re = (r₁w_m/v), Z = (z/r₁), and r₁/δ. The plug-flow model and the particle-trajectory model were used for calculating η. The results obtained by both models showed that η was a function of V_R, (C₁D_R²/Re)Z and r₁/δ. The particle-trajectory model showed a smaller value of η than the plug-flow model. The value of η calculated by the former model increased with increasing (C₁D_R²/Re)Z and decreased with increasing V_R. Although η did not change with r₁/δ when r₁/δ<1, it decreased gradually with increasing r₁/δ in the region of r₁/δ>1. The values of η for a channel induction heater installed in a continuous casting tundish were estimated to discuss the practicability of the present inclusion separator. It was found that η was greater than 95% for inclusion particles with the diameter greater than 60μm.