Furnace Route Research Articles

Process-level emission analysis and decarbonization pathway for BF-BOF route in Indian iron and steel industry

The blast furnace-basic oxygen furnace (BF-BOF) route contributes 46% to the production of iron and steel in India and is highly energy and emission-intensive. Its decarbonization needs to be prioritized for reducing long-term climate-related impacts. So far, studies have assessed the macro-level carbon emission and energy consumption of the entire industry (encompassing all production routes i.e., BF-BOF, EAF, DRI, SR-BOF, etc.), and lacks the specific plan for decarbonization of plants based on BF-BOF route. Secondly, these studies have focused on just a single input (raw material, energy, fuel, etc.) and the respective output (steel) and lack the analysis of detailed process-wise material and energy flow and consideration of fugitive emissions, which is needed for emission mitigation of entire BF-BOF based plants, which produces 57.37 million tons of crude steel in India. The current study addresses this gap through a case study of a BF-BOF-based plant by comprehensively analyzing the material and energy flow for each production step followed by assessing the respective carbon emissions. Further, a marginal abatement cost curve (MACC) is developed to identify the process-wise cost-effective mitigation measures. The current study shows that the implementation of proposed measures can significantly reduce carbon emissions from 3.3 to 2.43 tCO2/tcs, making it equal to the global counterparts.

A review on production and application of direct reduced iron in gas-based shaft furnace–electric arc furnace route

A review on production and application of direct reduced iron in gas-based shaft furnace–electric arc furnace route

Realization of Bio-Coal Injection into the Blast Furnace

The steel industry accounts, according to the International Energy Agency, for ~6.7% of global CO2 emissions, and the major portion of its contribution is from steelmaking via the blast furnace (BF) route. In the short term, a significant reduction in fossil CO2 emissions can be achieved through the introduction of bio-coal into the BF as part of cold bonded briquettes, by injection, or as part of coke. The use of bio-coal-containing residue briquettes was previously demonstrated in industrial trials in Sweden, whereas bio-coal injection was only tested on a pilot scale or in one-tuyere tests. Therefore, industrial trials replacing part of the pulverized coal (PC) were conducted. It was concluded that the grinding, conveying, and injection of up to 10% of charcoal (CC) with PC can be safely achieved without negative impacts on PC injection plant or BF operational conditions and without losses of CC with the dust. From a process point of view, higher addition is possible, but it must be verified that grinding and conveying is feasible. Through an experimentally validated computational fluid flow model, it was shown that a high moisture content and the presence of oversized particles delay devolatilization and ignition, lowering the combustion efficiency. By using CC with similar heating value to PC, compositional variations in the injected blend are not critical.

The Steelmaking Transformation Process and Its Consequences for Slag Utilization

The main challenge of the European steel industry for the next decade is the steel production transformation process. Many steel producers aim to avoid their CO2 emissions by substituting the CO2‐intensive blast furnace/basic oxygen furnace route by a gas‐based direct reduced iron (DRI) process combined with an electric smelting process. Thus, the well‐known latent hydraulic granulated blast furnace slag (GBS) will vanish step by step. For more than 140 years, this slag has been used as a supplementary cementitious material due to its clinker reduction potential and from there its CO2 reduction potential for the cement and concrete production. Moreover, slag cements offer some special technical advantages. Whereas the solid‐state DRI process itself does not generate any slag, the different electric smelting processes will produce liquid steel or “electric” pig iron, respectively, together with very different types of slags. However, specific slag/metal ratios, resulting slag volumes, chemical and mineralogical composition, and physical properties of the new slags are yet unknown. Therefore, their cementitious and environmental properties are also still unknown. Different current and scheduled projects aim mainly to enable the different types of new slags to substitute GBS to continue the successful cross‐industrial cooperation between steel and cement industry.

Substituting natural gas with hydrogen: A case study on mass, energy, and emissions in electric arc furnace steelmaking

This study sets out to explore the use of hydrogen into steelmaking via the electric arc furnace route, weaving together technoeconomic analysis with a comprehensive carbon footprint assessment. Through a detailed examination, we scrutinize the financial prospects of integrating hydrogen within a scrap-based steel mill, using Liberty GFG's data for a case study. Based on the data, the steel plant's annual consumption is 1.2 million GJ/y of energy, primarily derived from natural gas, to produce 0.75 million tonnes of steel. We explore the potential of replacing this natural gas with 10-kilotonnes of hydrogen per year (1.35 t/h), considering the steel mill's capacity factor of 0.82. By employing sophisticated flowsheet-based calculations, we unravel the environmental implications of integrating hydrogen into the steelmaking process. The investigation reveals that the plant consumes 2.9 GJ per tonne of steel from natural gas, indicating a demand of 23.5 kilograms of hydrogen to completely supplant natural gas. This equates to 2.35 kilograms of hydrogen per tonne of steel for every 10% displacement of natural gas. At present, the comprehensive cost of employing hydrogen stands at US$ 144 per tonne of steel, predicated on a wind electricity price of US$ 38 per MWh. In contrast, utilising natural gas amounts to US$ 58 per tonne of steel. However, the horizon holds promise for a substantial reduction in hydrogen costs over the next decade, heralding a potential paradigm shift in its utilisation. The emission analysis shows that the plant produces greenhouse gas emissions of 735 kgCO2e/t steel, out of which 70% is due to the use of dominant fossil electricity and the rest 30% (223 kgCO2e/t steel) from other carbon sources such as natural gas, lump coke, coke fines, and diesel fuel. Modeling proposes that a complete substitution of grid electricity and natural gas would lead to process emissions totaling 104 kgCO2e/t steel. To achieve a net-zero emission target, a strategic shift is suggested: replacing lump coke and coke fines with biochar. This substitution not only eliminates lifecycle emissions but also paves the path towards realising a sustainable, carbon-neutral future.

Development and assessment of an integrated wind energy system for green steelmaking based on electric arc furnace route

Optimizing energy structure is important for coping with the increasing environmental problems in iron and steel industry. Wind energy is one of typical zero-carbon, inexhaustible, and accessible energy source for alleviating energy dilemma. In this paper, the electric arc furnace steelmaking processes integrated with wind energy system (EAF-WES) is developed. The input-output data of 1214 and 1536 heats with 30 % and 50 % hot metal ratio are traced and collected. Life cycle assessment and techno-economic analysis of EAF route integrated with traditional energy system (EAF-TES) and EAF-WES are further researched and compared from perspectives of life cycle carbon footprint (LCCF), production cost, wind energy price (WEP), carbon efficiency, carbon reduction benefit (CRB), and carbon tax. The results indicate that EAF-WES enjoys lower LCCF but higher production cost and carbon efficiency than EAF-TES. Considering the price fluctuations, the optimal EAF steelmaking pattern with lowest production cost under different extent of WEP and carbon tax is suggested. When the electricity price is 0.043 and 0.046 $/kWh, the CRB is balanced. It is concluded that EAF-WES is a low-carbon, high-productive, environmentally friendly, and economical route. This research is expected to supply a technical idea for energy conservation and emission reduction in future steel production.

New methodology for estimating the influence of Cu content of Ferrous Scrap materials in the Total Cost of Operation (TCO) of scrap mix in Electric Arc Furnace steelmaking

Scrap is the main raw material of the electric arc furnace (EAF) route of steelmaking and an important one in the primary route. The decarbonisation commitment acquired by the most relevant steelmaking companies, will only increase the amount of scrap used by both routes, making it a critical component to succeed in the worldwide challenge of reducing CO2 emissions. While being a very relevant material, scrap characterisation is complex due to its heterogeneity, but furthermore, its quality is worsening as its demand increases. This includes the sterile content, such as copper. Higher sterile content scrap comes at a lower price, while scrap with a lower content in undesired elements is most costly. Being able to balance the cost and benefit of purchasing scrap with a higher or lower content of copper with a respective, lower or higher purchase cost would be of interest to optimise the mix and produce the required quality steel at the lowest possible cost. Nowadays, this cost benefit analysis can only be done by performing Total Cost of Operation (TCO) calculations that require a considerable amount of information, including but not limited to the complete chemical composition of scrap, market parameters, production forecast and other relevant data; moreover, involving an arduous optimization process. Based on a parametric study of the TCO calculation, this work proposes a mathematical model to estimate the impact on the TCO of a predefined scrap mix when only modifying the specifics of one given scrap type. The results would facilitate the decision making by comparing the two scenarios as a factor of cost. This mathematical model can be easily programmed and requires only 5 parameters to be run, while providing a low error result.

Blast Furnace Slag Formation Prediction Model Using Classical Thermodynamics

Blast furnace (BF) ironmaking is the most widely used technology for hot metal production. In steelmaking industry, 80% of the steel in the world is produced in the BF‐basic oxygen furnace route. It is well known that poor quality of the raw material i.e., high gangue content in the iron ore affects the BF process performance and the cohesive zone formation, which is the most critical zone in the BF operations. Increased gangue content in the iron ore causes variation in the slag formation and slag volume thus affecting the fuel rate and BF performance. Therefore, in this study, the slag formation is studied to understand the slag properties at different locations inside the BF. The model is based on classical thermodynamics and is implemented using ChemApp linked with FactSage databases. The model aids in understanding the slag formation in the BF for various burden chemistry, fuel, and flux inputs. The final hot metal and slag composition along with the exit gas volume and composition predicted from this model are compared with industrial BF plant data operating across different conditions.

Comparative analysis of process selection and carbon emissions assessment of innovative steelmaking routes

Innovative emission reduction technologies combined with optimized processes can effectively reduce the environmental pressure in the iron and steel industry (ISI). Identifying and comparatively analyzing the carbon emissions (CE) from steel productions is conducive to achieving China's ambitious carbon reduction targets. In this paper, we investigated two innovative routes: the shaft furnace-induction furnace-basic oxygen furnace route (SF-IF-BOF) and shaft furnace-electric smelting furnace-basic oxygen furnace route (SF-ESF-BOF), alongside two traditional routes: the blast furnace-BOF route (BF-BOF) and SF-electric arc furnace route (SF-ESF). The analysis was based on a functional unit of 1000 kg of crude steel (CS). By establishing the mass and energy balance models and decision criteria, 12 typical smelting scenarios for these routes were analyzed and compared in terms of materials consumption and CE. The results showed that increasing the proportion of scrap was beneficial for reducing CE. Under the condition of a 50% scrap ratio, the CE of the SF-IF-BOF, SF-ESF-BOF, BF-BOF, and SF-EAF routes were 768, 823, 946, and 870 kg, respectively. The SF-IF-BOF route displayed the most significant advantage of CE reduction. In addition, by using 100% zero-carbon electricity substitution, the SF-EAF route exhibited the greatest CE reduction effect of 41% (from 870 to 510 kg/t). While deploying 100% biomass fuels to replace coal, the CE of the BF-BOF route reduced by 80%. Finally, after introducing biomass fuels and zero-carbon electricity, the CE of the SF-IF-BOF route was minimized to a significantly low 13 kg/t (from 768), nearing zero CE. This research is expected to provide a novel solution for further CE reduction in the future of ISI, contributing to environmental sustainability and carbon reduction goals.

Comparative Technical and Economic Analyses of Hydrogen-Based Steel and Power Sectors

Decarbonizing the current steel and power sectors through the development of the hydrogen direct-reduction iron ore–electric arc furnace route and the 100% hydrogen-fired gas turbine cycle is crucial. The current study focuses on three clusters of research works. The first cluster covers the investigation of the mass and energy balance of the route and the subsequent application of these values in experiments to optimize the reduction yield of iron ore. In the second cluster, the existing gas turbine unit was selected for the complete replacement of natural gas with hydrogen and for finding the most optimal mass and energy balance in the cycle through an Aspen HYSYS model. In addition, the chemical kinetics in the hydrogen combustion process were simulated using Ansys Chemkin Pro to research the emissions. In the last cluster, a comparative economic analysis was conducted to identify the levelized cost of production of the route and the levelized cost of electricity of the cycle. The findings in the economic analysis provided good insight into the details of the capital and operational expenditures of each industrial sector in understanding the impact of each kg of hydrogen consumed in the plants. These findings provide a good basis for future research on reducing the cost of hydrogen-based steel and power sectors. Moreover, the outcomes of this study can also assist ongoing, large-scale hydrogen and ammonia projects in Uzbekistan in terms of designing novel hydrogen-based industries with cost-effective solutions.

The Influence of Nitrogen on Hydrogen Reduction of Iron Ore Pellets

As the iron and steel industry now strives for a carbon neutral industry, hydrogen‐based direct reduction shaft furnace technology has become an alternative to the heavily fossil‐depending blast furnace route. Research questions related to the future full‐scale production have, therefore, become more interesting. Depending on the operational conditions, the H2 concentration and temperature will vary across the length of the reactor. This work studies the effect of nitrogen in a hydrogen‐reducing gas during the reduction of commercial iron ore pellets using thermogravimetric analysis. The reducing gas consisted of either pure hydrogen or a mixture of 90–70 vol% hydrogen and 10–30 vol% nitrogen at 773, 873, 973, 1073, and 1173 K. It is found that the reduction rate decreased with decreasing temperature and increasing nitrogen content. The effect of nitrogen on the reduction rate is more profound than expected from the decreased hydrogen partial pressure alone. To aid the discussion, partially reduced pellets are studied using optical and scanning electron microscopy. It is found that the microstructure is strongly dependent on the temperature but independent of the nitrogen content.

Pressurized Chemical Looping for Direct Reduced Iron Production: Economics of Carbon Neutral Process Configurations

The replacement of the blast furnace—basic oxygen furnace (BF-BOF) steelmaking route with the direct reduced iron—electric arc furnace (DRI-EAF) route reduces the direct CO2 emissions from steelmaking by up to 68%; however, the DRI shaft furnace is one of the largest remaining point source emitters in steelmaking. The capital and operating expenses of two potential nearly carbon-neutral DRI process configurations were investigated as a modification to a standard Midrex DRI facility. First, amine-based post-combustion capture with a 95% capture rate was considered as the benchmark, as it is currently commercially available. A second, novel configuration integrated the Midrex process with pressurized chemical looping—direct reduced iron (PCL-DRI) production. The capital expenditures were 71% and 28% higher than the standard Midrex process for a Midrex + amine capture plant, and a PCL-DRI plant, respectively. There was an incremental variable operating cost of USD 103 and USD 44 per tonne of CO2 for DRI production using amine capture and PCL-DRI, respectively. The amine capture configuration is most sensitive to the cost of steam generation, while PCL-DRI is more sensitive to the cost of electricity and the makeup oxygen carrier. An iron-based natural ore is recommended for PCL-DRI due to the low cost and availability. Based on the lower costs compared to amine-based post-combustion capture, PCL-DRI is an attractive means of eliminating CO2 emissions from DRI production.

Comparing the decarbonization benefit provided by waste-based hydrogen routes to green steel production process: an analytical model

In the present context of global decarbonization, the steelmaking sector plays a key role. It is indeed one of the so-called hard-to-abate sectors. The high emissions from steelmaking depend on the use of the Blast Furnace-Basic Oxygen Furnace (BF-BOF) route, which generates 1.8 tCO2eq per ton of Liquid Steel (LS). The production of direct reduced iron (DRI) to power an electric arc furnace is currently the most adopted solution to achieve the decarbonization goals. This alternative, based on the use of natural gas, offers a decarbonization potential of about 34% compared to the BF-BOF route. The most promising alternative, however, consists of using electrolysis-based hydrogen (H2) to produce DRI. This solution would drastically reduce direct and indirect process emissions but requires a radical energy transition. In the current transition phase, waste-based H2 production routes could be attractive, but their potential need to be evaluated with respect to the steelmaking process. To this concern, the objective of the present work is to assess the decarbonization potential of three waste-based H2 production routes (i.e., gasification, incineration and anaerobic digestion-based) with respect to the electrolysis-based steelmaking route. An environmental analytical model was therefore developed to evaluate the total (i.e., direct, indirect, and avoided) greenhouse gases emissions associated with the production of 1 ton of LS by employing the different routes. A sensitivity analysis was also carried out to understand the benefit provided by each waste-based H2 alternative in the current energy transition phase. The results obtained confirmed the need for radical emission reductions from electricity generation to make electrolysis-based H2 production environmentally favorable and revealed a high decarbonization potential for waste-based routes in the current energy transition phase.

Methodology for qualifying the use of green steel in body components: A contribution to the life cycle engineering of steel

The use of materials with low environmental footprint will become more important for global car manufacturers in the future to comply the requirements and achieve the sustainability targets. The vehicle body of an electric vehicle is largely made of different steel grades and its production has a major impact on greenhouse gas emissions within the production stage. Future steel production will include a scrap-based electric arc furnace route. This route produces CO2-reduced steel products. However, these products are dependent on the scrap quality. Due to the high scrap content, impurities or tramp elements can be in the molten steel, reducing the steel end-quality or the properties of the final material and limiting reuse of the steel scrap. Therefore, a methodology is developed to perform an experimental analysis for data collection. Through this methodology, a recovery-process-structure-property correlation can be established and thus the influence of manufacturing-related impurities on the mechanical properties can be investigated. A case study shows initial research results using exemplary steel grades. The concept can examine the possibility of using steel with low carbon footprint to advance the life cycle engineering (LCE) idea in terms of recycling steel scrap and to reduce the environmental impact of body components by using CO2-reduced steel.

Steel, Aluminum, and FRP-Composites: The Race to Zero Carbon Emissions

As various regions around the world implement carbon taxes, we assert that the competitiveness of steel products in the marketplace will shift according to individual manufacturers’ ability to reduce CO2 emissions as measured by cradle-to-gate Life Cycle Analysis (LCA). This study was performed by using LCA and cost estimate research to compare the CO2 emissions and the additional cost applied to the production of various decarbonized materials used in sheet for automotive industry applications using the bending stiffness-based weight reduction factor. The pre-pandemic year 2019 was used as a baseline for cost estimates. This paper discusses the future cost scenarios based on carbon taxes and hydrogen cost. The pathways to decarbonize steel and alternative materials such as aluminum and reinforced polymer composites were evaluated. Normalized global warming potential (nGWP) estimates were calculated assuming inputs from the current USA electricity grid, and a hypothetical renewables-based grid. For a current electricity grid mix in the US (with 61% fossil fuels, 19% nuclear, 20% renewables), the lowest nGWP was found to be secondary aluminum and 100% recycled scrap melting of steel. This is followed by the natural gas Direct Reduced Iron–Electric Arc Furnace (DRI-EAF) route with carbon capture and the Blast Furnace-Basic Oxygen Furnace (BF-BOF) route with carbon capture. From the cost point of view, the current cheapest decarbonized production route is natural gas DRI-EAF with Carbon Capture and Storage (CCS). For a renewable electricity grid (50% solar photovoltaic and 50% wind), the lowest GWP was found to be 100% recycled scrap melting of steel and secondary aluminum. This is followed by the hydrogen-based DRI-EAF route and natural gas DRI-EAF with carbon capture. The results indicate that, when applying technologies available today, decarbonized steel will remain competitive, at least in the context of automotive sheet selection compared to aluminum and composites.

Toward the Decarbonization of the Steel Sector: Development of an Artificial Intelligence Model Based on Hyperspectral Imaging at Fully Automated Scrap Characterization for Material Upgrading Operations

Due to decarbonization commitment made by steelmaking companies, the steel industry is tackling a technological transition from blast furnace (BF)–basic oxygen furnace (BOF) route to direct reduction iron (DRI)–electric arc furnace (EAF) route. Under this scenario, ferrous scrap becomes a critical factor for reaching CO2 reduction challenge. However, ferrous scrap can be considered one of the most complex industrial raw materials. In addition, scrap presents a huge heterogeneity in both physical and chemical characteristics. However, for producing high‐quality steel products, certainty on scrap specifics is required. Herein, an artificial intelligent model based on spectral information for the segmentation of different materials contained in the ferrous scrap is proposed. Developed solution offers a processing pipeline through a 2D–3D convolutional neural network algorithm based on a dataset with more than 428 million of pixels through hyperspectral cameras in the 400–1700 nm range. By this model, the detection of ferric fraction, stainless steel, aluminum, zinc, copper, sterile, and rubber and plastic materials are assessed. This work aims at increasing the reliability of the steelmaking process by lowering the number of steel quality noncompliance rejection due to lack of knowledge and uncertainties of these raw material compositions.

Low carbon optimal planning of the steel mill gas utilization system

Decarbonization of the steelmaking industry is imperative in achieving the carbon neutrality target. This paper proposes a two-stage low carbon robust planning method for the steel mill gas utilization system (SMGUS), which is the major CO2 emission source of the conventional blast furnace route based-steelmaking plant. The planning aims to find the optimal installed capacities and relevant deployment time of multiple low-carbon technologies, such as renewable energy, energy storage, hydrogen energy and carbon capture & utilization, so that the demand of steel production can be met in an economically competitive and environmentally friendly way. Case studies are carried out on the low-carbon planning of a steelmaking plant with annual production of 1.5 million tons of crude steel, in which different carbon market conditions and CO2 reduction routes are considered. The results show that the low carbon planning can reduce the CO2 emissions to 1.22 tons per ton of steel by 2045–2050 through the proper deployment of the low carbon technologies. The CO2 emissions can be further reduced to 0.31 tons per ton of steel if the BF-BOF process is replaced by H2-DRI and EAF technologies. This paper presents an effective planning method for the decarbonization of steelmaking plant.

Influence of the Recirculation of Various by-products Generated through Electric Arc Furnace Route on EAF Slag Quality

Influence of the Recirculation of Various by-products Generated through Electric Arc Furnace Route on EAF Slag Quality

Review of Life Cycle Assessments for Steel and Environmental Analysis of Future Steel Production Scenarios

The steel industry is focused on reducing its environmental impact. Using the life cycle assessment (LCA) methodology, the impacts of the primary steel production via the blast furnace route and the scrap-based secondary steel production via the EAF route are assessed. In order to achieve environmentally friendly steel production, breakthrough technologies have to be implemented. With a shift from primary to secondary steel production, the increasing steel demand is not met due to insufficient scrap availability. In this paper, special focus is given on recycling methodologies for metals and steel. The decarbonization of the steel industry requires a shift from a coal-based metallurgy towards a hydrogen and electricity-based metallurgy. Interim scenarios like the injection of hydrogen and the use of pre-reduced iron ores in a blast furnace can already reduce the greenhouse gas (GHG) emissions up to 200 kg CO2/t hot metal. Direct reduction plants combined with electrical melting units/furnaces offer the opportunity to minimize GHG emissions. The results presented give guidance to the steel industry and policy makers on how much renewable electric energy is required for the decarbonization of the steel industry.

Electric Arc Furnace Reactive Compensation System Using Zero Harmonic Distortion Converter

Steel production worldwide continues to grow and, consequently, also the energy consumption of the steel sector. With the applications of the electric arc furnace route in the steelmaking process, the concern with aspects of power quality and overload of the transmission grid lines increases. This work presents the zero harmonic distortion (ZHD) converter static synchronous compensator (STATCOM), which makes it possible to increase the displacement power factor of an electric arc furnace (EAF) application from 0.88 to 0.98 with total demand distortion in the grid around 1.44% with the ZHD prototype operation, this being accomplished without using high-order sinusoidal filters and with consolidated components in the industry.