Student Number : 0318397E - MSc dissertation - School of Chemical and Metallurgical Engineering - Faculty of Engineering and the Built Environment / An experimental study of the effects of a slag phase on mass transport in a onefifth water model of a 100ton CLU-converter was conducted. The study was a follow up to earlier investigations conducted in the absence of a simulated slag phase. Kerosene (10% by volume) was used to represent the slag phase in the cold model experiments. The presence of a slag phase increased the mixing time of a tracer solution in the bath. The mixing time, defined at 99.66% bath homogeneity, was found to increase with bath height and a lowering gas flow rate. The functional relationship, Tmix = 4.39Q-0.73W0.24H1.12, was established as expressing the effect of gas flow rate (Q), bath weight (W), and bath height (H) on the mixing time (Tmix). The mixing time increased by an average of 16.3% after slag inclusion. The mass transfer parameter [(Reloc,r)0.25(Ret)0.32] values obtained in the absence of a slag phase decreased by an average of 32.2% with slag inclusion. Calculated mass transfer coefficients increased with gas flow rate and a decrease in bath height. The relationship, K Q0.08, showing derived mass transfer coefficient (K) dependence on the gas flow rate (Q) was established. The proportionality constant in the equation was observed to vary with bath height, gas flow rate and sample location. Contour maps representing variation of mass transfer coefficients in the bath regions were produced.

Low alloy steel electrodes have been electroslag remelted using alternating and direct current power sources. Changes in electrical contact between the furnace mould wall and mould base provided an improved understanding of the thermal ,and chemical processes characteristic of the remelting technique. 1m ion regeneration process has been postulated to account for current flow within the slag phase. Observed changes in furnace heating effects, electrode droplet sizes and in slag and metal compositions have be,en related to overtensions impressed on the slag/electrode and slag/ingot boundaries. The desulfurization reaction has been studied in detail. / Thesis / Doctor of Philosophy (PhD)