EMULSIFICATION AND MASS-TRANSFER IN LADLE METALLURGY

Measurements of slag emulsification in gas-stirred ladles were carried out in cold-model systems of different geometric sizes. Detaching of slag droplets - necessary for efficient emulsification - only takes place if the flow velocity at the slag/metal interface exceeds a certain level. The use of a centric nozzle leads at high gas flow rates to considerably larger degrees of emulsification than eccentric stirring. The reason of this phenomenon is that the recirculation flow during centric gas injection transports larger amounts of emulsified droplets into deeper regions of the melt while during eccentric stirring there is more time for reseparation of slag droplets into the top slag. Comparing emulsification results with mass-transfer measurements, the dependence between rate constants as well as degrees of emulsification and Froude number shows similar behaviour.