Steelmaking contributes by more than 5% to the world's anthropogenic CO2 emissions, so new ways to reduce the emissions in this industrial sector must be found. During a transition to more sustainable production concepts, also economic factors must be considered. In this paper the potential of using direct reduced iron (DRI) from the FASTMET process with rotary hearth furnace (RHF) technology, as a partial substitute of pellets in a blast furnace (BF) was studied. Simplified mathematical models of the different operations in a steel plant, including RHF, are combined with a more detailed model of the BF and the entire system is optimized by non-linear programming with respect to costs. The objective of the presented study is to analyze the prerequisites for an economical operation of an integrated steel plant equipped with an RHF, under different raw material prices and varying costs of CO2 emission allowances. The blast furnace operation parameters are also analyzed for different amounts of DRI charged. The results illustrate the conditions under which it would be beneficiary in a steel plant to integrate the RHF and BF technologies.

451 Cover Photo:Deformation-induced martensitic transformation, which offers high manganese steel superior combination of strength and elongation, is infl uenced strongly by thermal martensite in initial microstructure. The in-situ EBSD technique reveals, as shown in the fi gure by comparing with initial microstructure, quantitatively the changes of volume fraction in both /␣´martensites and their variants, for details, see text in pages 576.