Luckman Muhmood

Studies of dynamic mass transfer at the slag-metal interface - Interfacial velocity measurements

Abstract The dynamics of oxygen transport along the slag–metal interface of pure iron and alumina-saturated CaO–Al2O3–SiO2 slag was studied using high-temperature X-ray image analysis. The oscillations of the metal drop occurring due to the interfacial movement of oxygen atoms driven by Marangoni forces were studied in detail. The change in interfacial area during the oscillations was measured using a digitizing software and MATLAB. It was observed that the interfacial velocity as a function of oxygen exhibits insignificant variation with temperature. Further, the values obtained for the interfacial velocity using oxygen concentration difference at the interface were slightly lower in comparison to those using sulfur. The possible reason for this lower velocity could be that, although oxygen is a smaller atom compared to that of sulfur, the energy barrier at the free iron surface is higher for oxygen, thus hindering its motion along the interface.

Some Novel Studies of Thermodynamics, Kinetics and Transport Phenomena in Slags

Abstract The following paper revolves around the research work conducted in collaboration during Professor Iwases brief visits to the Materials Process Science Division at Royal Institute of Technology, Stockholm. The paper focuses on the thermodynamic aspects of CaO–FeO–SiO2 and CaO–FeO–SiO2–MnO slag oxidation in air and sulfur transport through CaO–Al2O3–SiO2 slag. Thermodynamics of slag oxidation in air opens potential new areas in terms of focus on effective recovery of iron oxide from slag. The slag transport studies are of fundamental nature and focuses on a novel technique to calculate the diffusion of species through slag by analyzing its corresponding concentration in the metal phase.

A New Approach for the Diffusion Coefficient Evaluation of Sulfur in CaO-SiO2-Al2O3 Slag

The Diffusion coefficient of sulfur in a ternary slag with composition of 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 was measured at 1723 K by chemical diffusion from the variation of concentration of sulfur in silver metal. A MATLAB program was developed to find the concentration variation of sulfur in silver metal using various critical parameters like the diffusion coefficient of sulfur in slag available in literature, sulfur partition ratio, sulfide capacity of the slag and the its density. The PS2 and PO2 pressures were calculated from the Gibbs energy of the equilibrium reaction between CaO in the slag and solid CaS and confirming the same by using ThermoCalc. The density of the slag at 1723 K was obtained from earlier experiments. Initially the order of magnitude for the diffusion coefficient was taken from the works of Saito and Kawai but later was modified so that the concentration changes of Sulfur obtained from the program agreed with the experimental results. The diffusion coefficient of sulfur in 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 slag at 1723 K was estimated as 4.14x10-6 cm2/sec.