Effects of Combined Electromagnetic and Bottom-Plug Stirring in a Steel Refining Ladle

Abstract

Abstract After being tapped from a basic oxygen furnace or electric arc furnace, the liquid steel must be refined at a ladle treatment station as part of alloying and quality improvement. In the ladle, the steel can be stirred using electromagnetic techniques, argon injection, or a combination of both methods. This work discusses the observed differences in stirring characteristics between these different approaches. Simulations of gas-stirring using a single plug, stirring using upwards electromagnetic stirring (EMS), downwards EMS, and the combination of electromagnetic stirring and single bottom plug with various plug positions in relation to the active EMS unit. The approach found in this work uses the CFD solver ANSYS Fluent to the simulate the isothermal multiphase flow field using a combined Eulerian and Lagrangian (E-L) approaches. The E-L approach with DPM uses a time-step (ts) of 1e−3s while the mixing study uses a ts of 0.1s. To improve simulation stability and computational speed, the Lorentz forces of the magnetic field data are imported directly into the simulation via User Defined Function and applied as a momentum source term onto the liquid steel. The flow field is monitored for quasi-steady state, upon which the momentum calculation is disabled and the secondary mixing study begins. The mixing study uses a tracer species to determine how long is required until homogeneity is reached. It was found that under standard stirring conditions, EMS has a faster mixing time than EM-Gas and gas-only, though both EMS and EM-gas see greater wall shear stresses.