Numerical simulation of magnetohydrodynamic two-phase flow and heat transfer in electroslag refining of electrolytic manganese metal

Electroslag remelting (ESR) technology has been innovatively employed to recycle the rejected electrolytic manganese metal (EMM) scrap. For a better understanding of the refining process, a transient three-dimensional comprehensive numerical model was developed based on computational fluid dynamics (CFD). With the assistance of the magnetic potential vector, the Maxwell's equations were solved for representing the electromagnetic fields. The movement of the manganese droplets was described by the volume of fluid (VOF) approach. A reasonable agreement between the simulations and experimental data is obtained. With the continuous melting of the EMM scrap, manganese droplets are formed at the inlet of the simulation domain and fall down and through to the slag phase afterwards. The highly conductive manganese droplet significantly changes the distribution of the current streamline and the Lorentz force around it. The droplet tends to rotate and move along the horizontal direction. With the current ranges from 5000 A to 8000 A, the volume-average Joule hating density and the time-average melt rate increase from 1.97×10 ⁷ W/m ³ to 5.25×10 ⁷ W/m ³ and from 0.029 kg/s to 0.073 kg/s, respectively. The average equivalent diameter of the manganese droplet increases from about 3.02 mm to 3.77 mm. The average residence time however first decreases from 5.12 s to 4.86 s and then rise to 5.24 s. The more vigorous molten slag would increases the motion path as well as the motion time of the droplet in the slag layer.