95 percent bulk mixing times in three different size water model ladles of a 140 T cylindrical shaped , dual plug ( located diametrically opposite at mid bath radius position) stirred, industrial ladle were determined experimentally with and without an upper buoyant phase. Based on dimensional analysis and a regression of the experimental data and, it was shown that in the inertial and gravitational force dominated flow regimes, 95 percent bulk mixing times for a slag-less situation can be described via(tau (mix,95 percent~2g/R))=2842.2(Q~2/gR~5)~(-0.28)(L/R)~(-1.04) Parallel to this, a large number of experiments were also carried out in one of the water models (D=0.30m) to quantify the influence of an upper buoyant phase on mixing. These indicated that mixing time, operating variables and thermo-physical properties of the upper phase liquid can be correlated via a dimensionless relationship of the type: (tau(mix,95 percent~2g/R))=1.76x10~4(Q~2/gR~5)~(-0.33)(L/R)~(-2.0)(L/R)~(0.6)(sigma~2/mu ~2gR)~(-0.022) in which, Q is the ambient gas flow rate, L is the depth of liquid , (AL) is the slag layer thickness and a and X are respectively the surface tension and viscosity of the upper phase fluid The dimensional analysis, regression of experimental data as well as the adequacy of the proposed correlations are discussed in the text.
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