Motions of alloying additions during furnace tapping in steelmaking processing operations

Numerical computations were carried out to describe the subsurface trajectories of spherically shaped particles (alloy additions) during simulated furnace to ladle tapping operations in steel-making. Complementing this, experiments in a 0.15 scale water model ladle of a 250 ton teeming ladle were also carried out so as to simulate the subsurface trajectories and total immersion times of various alloy additions as a function of (steel) jet orientation, jet entry locations, particle (alloy additions) entry location, particle shape, density,etc. Similarity criteria for model and prototype were deduced on the basis of Froude modeling. The possibilities of additions of various density being entrained into the bulk liquid and under-going prolonged subsurface motion were examined for a variety of operating conditions. It was found, however, that buoyant spherical particles with apparent densities ranging between 0.4 and 0.9 would, when projected into a recirculating water bath at velocities of 2.7 m/s, record total immersion times of only 0.1 to 40 seconds. The implications of the water model study, together with some idealized sets of computations for an industrial size 250 ton ladle, are analyzed from the viewpoint of industrial alloy addition practices. Finally, the results are examined with reference to different shaped particles and multi-particle addition procedures, since the latter are more typical of industrial practice.