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A new approach has been adopted to predict the contribution of the impact and slag-metal bulk zones to the refining rates of impurities in a top blown oxygen steelmaking process. The knowledge pertaining to the behavior of top-jets and bottom stirring plumes (water model and industrial studies) was adapted. For the impact zone, the surface renewal generated by the top jet as well as bottom stirring plumes is incorporated in the current model, whereas in the case of slag-metal bulk zones the surface renewal is caused solely by the bottom stirring plumes. This approach helped in achieving a more explicit use of process parameters in quantifying the slag formation. The results suggest a minor contribution of these two zones to the overall refining of impurities throughout the oxygen blow.

Bloated droplet phenomena play a vital role in the refining kinetics of basic oxygen steelmaking. Previous studies have developed extensive models to understand the kinetics of bloated droplets. However, no studies in the open literature address the thermal behavior of bloated droplets for a BOF (Basic oxygen furnace). The present work aims to develop a bloated droplet heat transfer model by incorporating the dynamic and chemical aspects taking place during the time of flight. The calculations were carried out with reasonable assumptions for a single droplet interacting with the slag/emulsion zone. The model was developed with the input experimental data (initial droplet temperature as 1853 K, initial diameter as 6.4 mm with a mass of 1 g, and a slag composition of 32 pct CaO, 35 pct SiO 2 , 17 pct Al 2 O 3 , 16 pct FeO) from Gu et al. Gu et al. and the results were validated. The study highlights the significance of how the chemical kinetics is influenced by the thermal characteristics of a droplet in a real BOF compared to the experimental scenario. The predicted results infer that the heat transfer contributed by radiation is 6 times greater than the convective heat transfer in a droplet. Moreover, by computing the droplet heat transfer efficiency, it was found that a droplet ejected from the hotspot losses approximately 73 pct of maximum heat to the surrounding.

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The COREX process is being projected as an alternative for blast furnace iron making. The coal consumption of the COREX process is large with a net fuel rate of~1000 kg/tone of hot metal (THM). The reason for a higher net fuel rate of the COREX process compared with the net coal rate for the blast furnace process has been investigated. Exergy analysis has been performed for identifying the causes, locations, and magnitudes of process inefficiencies for the COREX process. Whereas blast furnace process data are available in the literature, no systematic data for stream information of the COREX process are available for different input coal rates required for exergy computation. A composite model of the COREX process (i.e., models for the smelter gasifier and the reduction shaft) using FactSage 6.2 (Thermfact/CRCT, Montreal, Canada, and GTT Technologies, Aachen, Germany) is used to generate stream data. A new methodology for the calculation of exergy of the COREX process streams using the database in FactSage is proposed in this work. Exergy data for blast furnace process streams have been obtained from the literature. The exergy loss and exergy efficiencies of the COREX process are evaluated at various coal rates and compared with those of the blast furnace. Operating the COREX process is theoretically feasible at lower coal rates with higher exergy efficiencies when lesser export gas is generated.