Model calculations for mass transfer with mixing in ladle metallurgy

It is well known that in secondary metallurgy during gas stirring, zones with differing degrees of homogeneity can occur in the liquid steel. By means of model calculations it will be demonstrated under which conditions mixing has to be considered for mass-transfer phenomena, as for example desulphurization. Under unfavourable conditions, i.e. large regions with low flow velocities – so-called dead zones – and low values for the exchange volume flow between these regions and the bulk volume, the equalization of concentration will become the rate-determining step for the total mass transfer. In order to avoid or minimize dead zones, the general flow pattern in the ladle has to be optimized.