Internal Slags Reuse in an Electric Steelmaking Route and Process Sustainability: Simulation of Different Scenarios Through the EIRES Monitoring Tool

Electric steelworks can be considered virtuous industries, as they recover end-of-life products, the scrap, but margins of improvement exist for the sustainability of their production process. An increased internal reuse of by-products (e.g. slags) can provide economic advantages reducing raw material exploitation and avoiding disposal of wastes. Although slags reuse can imply significant advantages, their internal recycling is sometimes hampered because of their composition variability, which might lead to not perfectly known process behavior and effects on the final product. The paper faces this problem and presents a study related to the analyses of process behavior and performance in the case of slags' reuse in an Italian steelworks. An ad-hoc developed general purpose-monitoring tool was exploited to simulate and evaluate the technical feasibility of two case studies related to the replacement of lime and dolime with Ladle Furnace slag with or without the partial recovery of Electric Arc Furnace slag for the production of two steel families. The effect on the production route, the environmental and energy impacts and steel composition were evaluated through advanced simulations. In particular, the simulations show that lime and dolime replacement is possible by recovering only Ladle Furnace slag, as a small increase of 3-4% of required electric energy is compensated by a reduction of non-metallic raw materials of about 14-16% without negative effects on steel composition and metallic yield. In addition, the exploited tool proved to be valid to monitor slags' composition and to evaluate the suitability of slags' reuse on a cast-by-cast basis.