Mixing phenomena in a VOD ladle were characterized by a watermodel simulation from the determination of mixing times by electrical conductivity measurements. Two mixing times defined for two degrees of mixing, viz., t95 (95 % mixing) and t99 (99 % mixing) were identified for each experiment. Various operating conditions as well as different placements of bottom nozzle with and without a top jet were simulated. Irrespective of whether the top blow is present or not, mixing rates were found to be increasing considerably as the nozzle position is moved from the center to the mid-radius position. The presence of a top jet, as in a VOD ladle, was found to weaken mixing for both a coaxial and non coaxial placement of the lance with the bubble plume. The results of watermodel experiments have been used to construct a simple two-tank model of mixing inside the actual ladle, in which the parameters are obtained as functions of process variables.
The Iron and Steel Institute of Japan