A model test for emulsion in gas-stirred ladles

Abstract

At high gas‐stirring rates of liquid metals in ladles covered with slag emulsification of slag droplets into the metal melt occurs. Emulsification intensifies the rate of slag‐metal extracting reactions. A theoretical model of the emulsification process was developed. The equilibrium between buoyancy, surface, and inertial force at the location where the slag droplets are formed determines the critical liquid metal velocity for drop formation. The amount of droplets formed per time depends on the flow of kinetic energy in the thin slag layer accelerated by momentum transfer from metal to slag. Experiments on a water model were carried out to determine the drop sizes, the number of droplets formed per time and the drop flow paths. Consequences for the amount of emulsification in steel melts are drawn.

Effect of Fluid Physical Properties on the Emulsification

“…[1][2][3][4][5][6][7][8] Role of the physical properties of the fluids on the emulsification and the size of entrained droplets are studied by water models. [1][2][3][4] Harman and Cramb 4) have defined relation for the critical velocity of denser phase for the occurrence of emulsification.…”

Modeling of Slag Entrainment and Interfacial Mass Transfer in Gas Stirred Ladles

“…5) The entrainment rate was estimated using the models of Oeters 31) (also found elsewhere 32,33) ) for a given average droplet size. For droplet residence time a value of 45 s was obtained as a fitting parameter to their overall model so as to yield an 'emulsification fraction' of 45 to 100%.…”

“…Given their measured droplet sizes to be smaller than 2.5 mm, their predicted residence time is quite low. The models of Oeters [31][32][33] have not been adequately validated and in the light of these contradictions its use is questionable. In contrast, the present work has dedicated models developed for each entrainment parameter leading to mass transfer rate predictions that are self consistent and agree with literature correlation; the overall model is not simple due to the complexity of the slag entrainment phenomena.…”

State of the art in the control of inclusions during steel ingot casting

“…Emulsification of the slag layers that float on the top of molten steel in gas-stirred vessels has been extensively investigated. [180,181,182] For the bottom pouring ingot casting process, slag entrainment into the molten steel in mold is affected mainly by the following: vortexing, method of powder addition, runner and ingate design, filling rate, turbulence at the meniscus, and slag properties.…”