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In FY-20, India’s steel production was 109 MT, and it is the second-largest steel producer on the planet, after China. India’s per capita consumption of steel was around 75 kg, which has risen from 59 kg in FY-14. Despite the increase in consumption, it is much lower than the average global consumption of 230 kg. The per capita consumption of steel is one of the strongest indicators of economic development across the nation. Thus, India has an ambitious plan of increasing steel production to around 250 MT and per capita consumption to around 160 kg by the year 2030. Steel manufacturers in India can be classified based on production routes as (a) oxygen route (BF/BOF route) and (b) electric route (electric arc furnace and induction furnace). One of the major issues for manufacturers of both routes is the availability of raw materials such as iron ore, direct reduced iron (DRI), and scrap. To achieve the level of 250 MT, steel manufacturers have to focus on improving the current process and product scenario as well as on research and development activities. The challenge to stop global warming has forced the global steel industry to strongly cut its CO2 emissions. In the case of India, this target will be extremely difficult by ruling in the production duplication planned by the year 2030. This work focuses on the recent developments of various processes and challenges associated with them. Possibilities and opportunities for improving the current processes such as top gas recycling, increasing pulverized coal injection, and hydrogenation as well as the implementation of new processes such as HIsarna and other CO2-lean iron production technologies are discussed. In addition, the eventual transition to hydrogen ironmaking and “green” electricity in smelting are considered. By fast-acting improvements in current facilities and brave investments in new carbon-lean technologies, the CO2 emissions of the Indian steel industry can peak and turn downward toward carbon-neutral production.

Commercial computational fluid dynamics (CFD) packages lack the flexibility to integrate additional physics for developing packed-bed simulation tools for complex metallurgical processes such as pellet induration furnaces. These solutions are also unsuitable for online deployment in plant operation control rooms. As a result, many researchers have developed models using in-house codes, but these models often lack computational efficiency, parallel processing capabilities, and robustness. This work leverages the flexibility and parallelization potential of open-source codes by developing a three-dimensional comprehensive tool using OpenFOAM to simulate the straight-grate iron oxide pellet induration furnace. The induration furnace is designed for efficient heat and mass transfer between the moving pellet bed and the flowing gas. The model incorporates various heterogeneous gas-solid reaction kinetics and other relevant physicochemical phenomena. The developed model has been extensively validated against experimental and numerical data reported in the literature, as well as actual plant-scale measurement using a Therm°Car test. This confirms the model accuracy and reliability as a real-time monitoring tool in plant operational control rooms. Furthermore, a case study is presented to demonstrate the model capability by focusing on the effect of a blinded grate bar on the pellet bed thermal profile and gas flow distribution.

Co-injection of natural gas (NG) with pulverized coal (PC) is carried out in blast furnace to increase the coal burnout; however, it has major challenges such as excess heat load on tuyere, lance overheating and competition between coal volatile matter and NG for available oxygen. A 3D computational fluid dynamics model of the blast pipe-tuyere-raceway region is developed to study the effects of: (1) NG and PC injection (PCI) through the co-axial lance and the subsequent oxygen enrichment on coal burnout and (2) relative positioning of NG and PCI lances in a double-lance design on coal burnout and localized temperature rise on PC lance. In the co-axial lance case, the use of NG as a cooling gas instead of oxygen decreases burnout from 54 to 43%. In double-lance design, positioning NG lance prior to PC lance results in relatively higher % burnout than the reverse configuration and does not lead to the overheating on PC lance.

Diffusion phenomena are of great importance in materials processing wherein atomic, molecular or ionic species are distributed within a phase or among different phases. Though the phenomenological equation describing the diffusion phenomena including the bulk flow arising out of diffusion in fluid and the phenomena of Kirkendall shift in substitutional solids are the same, these processes are often treated independently. Some discussion on this aspect is presented in the theoretical aspects of diffusion. Owing to the complexity of atomic interactions, prediction of diffusion coefficients in condensed systems from first principles may not be that reliable; Experimental determination of diffusion coefficients is essential. In the second section, some novel experimental techniques developed recently to measure diffusion coefficients in the solid state as well as liquid systems including those in slags are described. In the last section, two case studies on application of diffusion phenomena in process metallurgy are presented emphasizing the importance of these in metallurgical processing.

The Diffusion coefficient of sulfur in a ternary slag with composition of 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 was measured at 1723 K by chemical diffusion from the variation of concentration of sulfur in silver metal. A MATLAB program was developed to find the concentration variation of sulfur in silver metal using various critical parameters like the diffusion coefficient of sulfur in slag available in literature, sulfur partition ratio, sulfide capacity of the slag and the its density. The P S2 and PO2 pressures were calculated from the Gibbs energy of the equilibrium reaction between CaO in the slag and solid CaS and confirming the same by using ThermoCalc. The density of the slag at 1723 K was obtained from earlier experiments. Initially the order of magnitude for the diffusion coefficient was taken from the works of Saito and Kawai but later was modified so that the concentration changes of Sulfur obtained from the program agreed with the experimental results. The diffusion coefficient of sulfur in 51.5% CaO- 9.6% SiO2- 38.9% Al2O3 slag at 1723 K was estimated as 4.14×10-6 cm2/sec.

Simulation of gas flow in a multilayered non-isothermal packed bed is useful for blast furnace operators in deciding appropriate charging strategy. While using an anisotropic form of Ergun equation to simulate gas flow through such systems, a new solution methodology for non-isothermal gas with varying density flowing through a layered burden has been proposed. This involves handling non-linearity due to gas density variation with pressure and temperature by solving for the square of pressure instead of pressure directly and handling the non-linearity due to |v| term in the Ergun equation by solving linearized form of Ergun equation and updating |v| iteratively. The proposed scheme is capable of predicting the effect of layer structure on gas flow with economy in number of grid points as well as computation time.

In the present work, the change of the interfacial tension at the slag-metal interface for sulfur transfer between molten iron, slag, and gas phases was monitored by X-ray sessile drop method in dynamic mode in the temperature range of 1830 to 1891 K. The experiments were carried out with pure iron samples immersed partly or fully in the slag phase. The slag consisted of 30 wt pct CaO, 50 wt pct Al2O3, and 20 wt pct SiO2 (alumina saturated at the experimental temperatures) with additions of FeO. Metal and slag samples contained in alumina crucibles were exposed to a CO-CO2-SO2-Ar gas mixture with defined oxygen and sulfur partial pressures, and the change of the shape of the metal drop was determined as a function of time. The equipment and the technique were calibrated by measurements of the surface tensions of the pure Cu, Ni, and Fe containing two different amounts of dissolved oxygen. A theoretical model was developed to determine the sulfur content of the metal as a function of time on the basis of sulfur diffusion in the slag and metal phases as well as surface tension-induced flow on the metal drop surface. Attempts were made to compute the interfacial tensions on the basis of force balance.

In the present work, the deoxidation of liquid steel with aluminum wire injection in a gas-stirred ladle was studied by mathematical modeling using a computational fluid dynamics (CFD) approach. This was complemented by an industrial trial study conducted at Uddeholm Tooling AB (Hagfors, Sweden). The results of the industrial trials were found to be in accordance with the results of the model calculation. In order to study the aspect of nucleation of alumina, emphasis was given to the initial period of deoxidation, when aluminum wire was injected into the bath. The concentration distributions of aluminum and oxygen were calculated both by considering and not considering the chemical reaction. Both calculations revealed that the driving force for the nucleation fo Al2O3 was very high in the region near the upper surface of the bath and close to the wire injection. The estimated nucleation rate in the vicinity of the aluminum wire injection point was much higher than the recommended value for spontaneously homogeneous nucleation, 103 nuclei/(cm3/s). The results of the model calculation also showed that the alumina nuclei generated at the vicinity of the wire injection point are transported to other regions by the flow.