As carbon dissolution rates have been determined for a few chars only, a systematic and comprehensive study was undertaken in this project on the dissolution behaviour of carbon from non-graphitic materials into liquid iron. In addition to measuring the kinetics of carbon dissolution from a number of coal chars into liquid iron as a function of parent coal and coal ash composition, the influence of chemical reactions between solute/solid carbon and ash oxides was also investigated. These studies were supplemented with investigations on one metallurgical coke for the sake of comparison. The wettability of coal chars and coke with liquid iron at 1550 degrees C was measured as a function of time. Being essentially non-wetting, only a marginal improvement in contact angles was observed with time. The accumulation of alumina at the interface was detected for all materials and was seen to increase with time in all cases. Calcium and sulphur also appeared to preferentially accumulate at the interface, concentrating at levels in excess of those expected from the ash composition alone. Despite the high levels of silica in the ash initially, very little silica was detected in the interfacial region, implying ongoing silica reduction reactions. A small amount of silicon was however detected in the iron droplets, indicating silica reduction with solute carbon. It was identified that the reduction reactions can also consume solute carbon in the liquid iron. As this is occurring simultaneously with carbon dissolution into liquid iron, the interdependency of silica reduction and carbon dissolution could potentially limit the observed carbon dissolution rate. A theoretical model was developed for estimating the interfacial contact area between chars and liquid iron. Wettability was found to have a very significant effect on the area of contact. A two-step behaviour was observed in the carbon dissolution of two chars and coke. Slow rates of carbon dissolution in stage II were attributed to very high levels of interfacial blockage by reaction products leading to much reduced areas of contact between carbonaceous material and liquid iron. The first order dissolution rate constants for four chars/coke and the observed trend in first order dissolution rate constants were calculated. These dissolution results compare well with the previously measured dissolution rate constants. The trends in dissolution can be adequately explained on the basis of carbon structure, silica reduction, sulphur concentration in the metal and ash impurities.

No description available.

<p> Levitation melting was used to measure the equilibrium between H2-H2o or CO-C02 gas mixtures and pure Fe or Fe-Cr alloys over the temperature range 1550 - 1750°C. The effects of thermal diffusion on the two types of gases were investigated. First and second order interaction parameters were employed to describe the interaction between oxygen and chromium {up to 25 wt. pct. of Cr.). </p> / Thesis / Master of Science (MSc)

<p> Iron-vanadium alloys were levitation melted and equilibrated at controlled temperatures with water vapour/hydrogen atmospheres of controlled composition, quenched and analysed for oxygen. The effect of vanadium on the behaviour of oxygen has been expressed in terms of first order free energy, enthalpy and entropy interaction parameters. </p> <p> The reduction of phosphorus from synthetic blast furnace slags by carbon saturated iron was studied under laboratory conditions. The rate of phosphorus transfer was determined and the results have been interpreted in terms of chemical reaction control at the slag/metal interface. </p> <p> The dephosphorisation of induction melted mild steel by synthetic basic slags was investigated. The rate of dephosphorisation was determined and the results have been interpreted in terms of mass transfer control in the slag phase. </p> / Thesis / Doctor of Philosophy (PhD)