Physical Chemistry Aspects of Liquid Metal Alloys, Molten Oxides and Waste Materials

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This research program has been designed with the following objectives in mind: 1) Development of fundamental knowledge that pertains to the processing of liquid metal alloys and the behaviour of oxide melts related to the recovery of useful products from waste materials; and 2) Research on thematic topics that will provide students with both fundamental knowledge and hands-on training experience in high temperature experimental techniques and materials characterization procedures that will fit them well for professional careers within academia, government laboratories and the industrial sector. In recent years, studies have been conducted within the applicant's laboratory to investigate the kinetics of decarburization of levitated stainless steel droplets with CO2-Ar gas mixtures. It was found that mass transfer correlations, although widely employed, do not describe the data obtained from droplet experiments. This was not understood before. Based on these findings, studies will be carried out to examine the influence of different temperature gradients within a reactive gas phase on experimentally determined kinetic parameters associated with different alloy systems. In this context, droplet experiments will be performed to examine the potential for simultaneously removing the impurities carbon and sulphur from levitated droplets of blast furnace hot metal composition with gas mixtures that contain CO2. Desulphurization experiments will also be conducted at lower temperatures where the iron solvent is replaced with copper or nickel. Results from these experiments together with numerical modelling will permit new mass transfer correlations to be established for characterization of refining reactions associated with levitated droplets exposed to reactive gas mixtures over an extended temperature range. In addition to refining reactions involving gas-metal interactions, steelmaking processes are based on control of slag chemistry, which in turn has a profound influence on slag performance and hence on steel quality. Recent studies by the applicant have included investigation of red mud, a waste material produced in the process of alumina extraction from bauxite, as a potential source of slag additives for the steel industry. The innovative production of refining fluxes for the steel industry from waste products generated by the aluminum industry has important environmental and also economic implications. During the proposed research, the feasibility of recovering iron from red mud by a novel mechanically activated reduction method will be evaluated and for the first time, the potential for generating mold fluxes from the residual waste material will be investigated. In addition, the possibility of a correlation between a measurable parameter of the molten oxide (e.g. electrical conductivity) and refining capacities will be explored in order to provide the basis for an online control system for production processes.