Refining fluxes for metallurgical melts based on waste materials of the aluminium industry

Waste slag is a major source of environmental pollution within the metallurgical industry. In the steel industry, about 100–150 kg of waste slag is produced in making one tonne of liquid steel in addition to that produced during ironmaking. In the aluminium industry, about 2–4 tonnes of waste materials are generated during the production of one tonne of aluminium. The waste products from these two industrial sectors are of particular concern because of the sheer volume and causticity of the materials. Extensive studies have been carried out at the University of Toronto to investigate potential applications for these metallurgical waste products. Studies have included: (1) desulphurization of hot metal and liquid steel using calcium aluminate fluxes made from the dross of aluminium electrolysis and remelting; (2) ferronickel desulphurization as well as simultaneous desulphurization and dephosphorization using red mud and white mud generated during alumina extraction from bauxite; and (3) recovery of nickel from spent catalysts generated by the petroleum industry. The results confirm that the application of waste byproducts from the aluminium industry, as a basis for refining fluxes in the steel industry, could be beneficial from technical, economical and environmental perspectives, thus generating social benefits for both industrial sectors.