Furnace Process Research Articles

Development and assessment of a biomass-based energy system for green steel production: A thermodynamic study

ABSTRACT Steel is the fundamental pillar of contemporary society, given its significant greenhouse gas emissions, rapid transformation is required for deep decarbonization of the iron and steel industry. This paper proposes a strategy to generate green steel through the H2-DRI-EAF (Hydrogen direct reduced iron processed in an electric arc furnace) process, leveraging biomass as the primary feedstock. The proposed configuration contains a biomass gasifier to generate hydrogen, which is further used in a shaft furnace to reduce iron ore and is fed to an electric arc furnace to produce Green Steel. India serves as the focal point for this study, with agricultural residue from the four most abundant crops selected as the primary feedstock. With these chosen feedstocks, the system demonstrates the capacity to produce approximately 0.1 kg of hydrogen per kg of biomass. Operating with an overall energy efficiency of 29.2% and exergy efficiency of 41.4%, the plant exhibits a crucial characteristic: the ability to seamlessly integrate different feedstocks without significantly affecting its overall performance. The aim of the current study is to promote bioenergy as a viable pathway for the decarbonization of steelmaking processes.

Direct Ink Writing and Rapid Microwave Sintering of Alumina

The additive manufacturing of ceramics is gaining attention due to difficulties in fabricating complex ceramic parts because of its hard and brittle nature. Direct ink writing (DIW) is a unique process in which solid-loaded slurry is extruded to print complex-shaped ceramic parts directly. In the present work, a new composition of high-solid loaded (76 wt.%) alumina ink is prepared for printing ceramic parts with complex structures. The rheology of ink is optimized to ensure the shear thinning behavior of the ink, while thermogravimetric analysis (TGA) of the printed part was carried out to optimize the debinding temperature. The printed alumina part is sintered using the conventional furnace and rapid microwave sintering process, and a comparison has been made. Microwave, a rapid sintering method with a high heating rate, produced >97% dense specimen, while the hardness and flexural strength values of 15.18 ± 0.6 GPa and 148.87 ± 2.14 MPa were achieved, respectively. Rapid microwave sintering of additively manufactured ceramic parts can reduce the energy consumption and overall production time needed to manufacture ceramic parts.

Validated kinetic modelling of ladle furnace process for predicting inclusions in API steel grade

A kinetic model of ladle furnace (LF) process is developed in C++ format using the FactSage database and ChemApp subroutines. The model considers all the process parameters such as ferroalloy and slag dissolution, wire additions, electrical arcing, steel/slag reactions, reoxidation due to slag eye opening, heat exchange between metal/slag, and refractory dissolution. Further, a correlation for inclusion removal rate was developed as a function of argon flow rate, using discrete phase method (DPM) in Computational Fluid dynamics (CFD). Lollypop samples from steel bath and slag samples were collected from the plant for API steel grade for chemical analysis and inclusion characterisation. At LF_in, the inclusions found were mostly alumina spinel with very low amount of Mg (∼3%), followed by spinel at intermediate stage having ∼15 wt. % of Mg and after Ca treatment, inclusions transformed into CaS and Calcium Aluminate type of inclusions. Overall inclusion weight fraction varied from 136 ppm at LF_in to 93 ppm at LF_out. The model calculations were found to give very good prediction for steel and slag chemistry, and inclusion global composition as compared to the plant results. Predicted temperature was found with an accuracy of ± 5 oC, while the calculated inclusion weight fraction was having an accuracy of ±12 ppm.

Reduction Behavior of Lump Ore and Its Applicability During Hydrogen-Based Shaft Furnace Process

Reduction Behavior of Lump Ore and Its Applicability During Hydrogen-Based Shaft Furnace Process

Evaluation of Some Uncertainties in the Modeling of Blast Furnace Hydrogen Injection

While blast furnaces remain the dominant ironmaking technology, there is growing interest in using hydrogen to partially replace coke and pulverized coal to reduce CO2 emissions in this hard‐to‐decarbonize process. However, significant discrepancies in modeling the tuyere injection of hydrogen are noted in the literature, which can challenge the scale‐up from modeling predictions and pilot trials to actual blast furnace operations. To address this, the impact of uncertainties in the assumptions of the temperature in the thermal reserve zone and the ratio of H2 and CO utilization on the results of blast furnace process modeling are evaluated using a 1D steady‐state zonal model. The study indicates that variations in the assumed value of thermal reserve zone temperature significantly impact the estimation of optimal hydrogen injection rate, coke replacement ratio, and direct CO2 emissions reductions. In contrast, the same parameters are much less affected by the variations in the assumed value of the proportion between H2 and CO utilization ratios, which, however, affect the top gas composition. A need for further research to determine the range of the difference in temperatures of gas and solid in the thermal reserve zone tolerable for smooth blast furnace operation is highlighted.

Comparative energy, emissions and economic assessment of low-carbon iron and steel making processes using imported liquid organic hydrogen carrier options

Hydrogen (H2)-based steel making is expected to become a major driver of intercontinental low-carbon H2 imports. Eight H2 supply scenarios based on either local H2 production at major steel producing locations (Germany/Japan), or liquid H2 carrier (dibenzyltoluene/perhydrodibenzyltiluene, DBT/PDBT) import from the United Arab Emirates, and their integration with H2 direct reduced iron (H-DRI) and electric arc furnace (EAF) processes, are investigated using process modeling. Solar energy-based PDBT import using surplus heat for dehydrogenation is the most cost-competitive H2 import scenario in Germany's case (levelized steel production cost, ∼685 $/tLS, with carbon emissions, ∼237 kgCO2/tLS). In Japan's case this scenario is the most economically favorable of all scenarios (∼736 $/tLS), with emissions (∼350 kgCO2/tLS) comparable to natural gas-DRI-EAF with 50% carbon capture. Steam methane reforming with carbon capture-based PDBT import is neither environmentally nor economically viable. PDBT-based H-DRI-EAF production cost is sensitive to electricity, H2 production, dehydrogenation energy, and carbon costs.

A Robust Static Model of Basic Oxygen Furnace for Analyzing Emerging Steelmaking Scenarios

A robust static model, which incorporates emerging steelmaking scenarios in terms of solid charge mix with the given hot metal in basic oxygen furnace process, is developed. It employs mass and enthalpy balances to comprehend nonequilibrium conditions, considering four key empirical parameters: iron loss, post‐combustion ratio, heat loss, and undissolved lime content in slag, which are fine‐tuned using plant data through a multivariate approach, ensuring the reliability. The model is validated in a basic oxygen furnace (BOF) shop using data from over 4000 heats, achieving a strike rate of ≈77% for input lime prediction within ±1 ton and ≈80% for input oxygen prediction within ±600 Nm3. Model implementation in BOF shop provides valuable guidance to the operators, resulting in the reduction of average oxygen and lime consumption by 139 Nm3 and 652 kg heat−1, respectively. The model also enables the determination of the maximum scrap utilization of ≈16% for 0.8% silicon and ≈14% for 0.6% silicon in hot metal, respectively. The model aids in calculating the maximum tap temperature for varying hot metal silicon and iron ore addition. Overall, the model optimizes primary steelmaking, enhancing efficiency, reducing resource consumption, and offering insights into alternative iron sources like direct reduced iron.

Studies to determine the influence of the basicity modulus on the qualitative and quantitative indicators of production technology and the material composition of the sintere

In recent years, the increase in the efficiency of the blast furnace process is largely associated with the use of sinter with improved metallurgical properties. In the blast furnace charge of PJSC NLMK, the share of sinter is 60–75% with a change in basicity from 1.3 to 1.8. Studying the material composition of agglomerates of different basicity and their characteristics allows us to adjust the technological process and determine the optimal modulus of basicity depending on specific conditions. Agglomerates with a basicity index of: 1.3; 1.4; 1.5; 1.6; 1.7 and 1.8. As a result of the research, it was established that the maximum vertical sintering speed and specific productivity of the sintering process correspond to the basicity of the sinter of 1.7. The influence of the basicity of the agglomerate on its strength is extreme, with a basicity of 1.4 the minimum strength of the agglomerate was obtained. Increasing the basicity of the agglomerate by more than 1.4 monotonically increases its strength. The nature of the change in the strength of the ag-glomerate with a change in basicity is determined by the mineral composition of the binder and is associated with a decrease in the proportion of glass in the structure of the agglomerate and an increase in the proportion of the crystalline silicate-ferrite binder. When studying the material composition, it was established that the samples of agglomerates have an identical phase composition, but differ in the phase ratio. Crystallization of calcium ferrites in contact with iron oxides contributes to the strengthening of the agglomerate, and the presence of impurities (Al, Si, Mg) in them increases the melting point. As a result of mineralogical and analytical studies, it was established that the highest metallurgical properties are found in agglomerates with a basicity modulus of 1.6–1.8.

Towards green steel-energy and CO2 assessment of low carbon steelmaking via hydrogen based shaft furnace direct reduction process

Under current stringent climate policies, the iron and steel industry, as a major contributor to industrial CO2 emissions, urgently needs the development of low-carbon metallurgical technologies. This work focuses on the hydrogen-based shaft furnace process, which can utilize green energy to significantly reduce CO2 emissions. This work combines the hydrogen-based shaft furnace CFD model, regression equations, and Aspen Plus model to develop a multi-gas source DR (Direct Reduction) plant model. This combination significantly reduces computation time while maintaining predictive accuracy. The transformation from COG (Coke Oven Gas)-DR to H2-DR plant was studied, showing that the top gas circulation process greatly reduces the net carbon input of the entire DR plant. However, the energy consumption of electrolytic hydrogen production limits the transformation of COG-DR plant to H2-DR plant. The process CO2 emissions depend largely on electrical energy footprint. Under traditional electrical energy footprint, the CO2 emissions of H2-DR-EAF (Electric Arc Furnace) route are about four times those of the COG-DR-EAF route. Only when using green source energy does the H2-DR-EAF route achieve the lowest CO2 emissions among all routes, at 344 kg/tls, which is 79 % lower than that of the BF (Blast Furnace)-BOF (Basic Oxygen Furnace) route.

White phosphorus production by a carbothermic reduction of upcycled crude phosphoric acid

White phosphorous is a critically important material in manufacturing semiconductors and advanced pharmaceuticals. However, white phosphorus is produced by only four countries using the huge energy-consuming electric arc furnace process. These four countries have resorted to banning or restricting their exports causing a supply risk for white phosphorus for many industrialized countries.To meet the white phosphorous supply risk, the never-existing white phosphorous production process has been developed by applying the carbothermic reduction of P2O5 gas provided by the thermal decomposition of phosphoric acid. The novel process can produce semiconductor-grade high-purity white phosphorous from crude phosphoric acid recovered from secondary phosphorous resources.By supplying phosphoric acid in the form of small droplets, we have achieved continuous operation of white phosphorus production, which was previously impossible, and brings production efficiency to an industrial level. This process could significantly reduce the supply risk for countries that rely entirely on imported white phosphorus.

Energy and Exergy Analysis of an Improved Hydrogen-Based Direct Reduction Shaft Furnace Process with Waste Heat Recovery

The traditional production mode using coal as the main energy source is not conducive to the sustainable development of the iron and steel industry (ISI). The hydrogen-based direct reduction shaft furnace (HDRSF) process is a feasible technical route for promoting the green development of the ISI. However, there is a lack of comprehensive analysis with respect to the energy utilization and process flow of the HDRSF method. To address these issues, a systemic material–energy–exergy model of HDRSF is established. An improved HDRSF process incorporating waste heat recovery is also proposed, and energy consumption intensity and exergy intensity are used as assessment metrics. This study’s findings indicate that the proposed waste heat recovery can considerably lower gas demand and energy consumption intensity, but exergy intensity has little effect. The reducing gas demand drops from 2083 m3 to 1557 m3, the energy consumption intensity drops from 2.75 × 107 kJ to 1.70 × 107 kJ, and the exergy intensity drops from 1.08 × 107 kJ to 1.05 × 107 kJ when the reducing gas temperature is 900 °C, H2:CO = 1:1; meanwhile, the recovery rate of waste heat reaches 40%. This study can serve as a reference for actual HDRSF process production.

Potential of controlling the steel-making process in electric arc steel-making furnaces to optimize technical and economic performance

Potential of controlling the steel-making process in electric arc steel-making furnaces to optimize technical and economic performance

Research on Mathematical Model and Process Parameter Optimization of Rotary Hearth Furnace Process Toward Energy and Cost Saving

Research on Mathematical Model and Process Parameter Optimization of Rotary Hearth Furnace Process Toward Energy and Cost Saving

Research of Reactions on Ferronickel Laterite by Rotary Kiln Furnace Process

Nickel is an important strategic metal, which is mainly used for the production of a wide range in the production of various anti-corrosion steels. Electric furnace, rotary kiln and smelting is currently the world-wide integration process for the production of ferronickel from nickel laterite ore, despite its high energy consumption. In this study, with the aim of providing some meaningful analysis for the production of ferronickel and reactions formed in the rotary kiln. The samples obtained were analyzed under conditions including reducing parameters (temperature and time) and smelting parameters (CaO, Al2O3 and MgO ratios). The metal content as well as the Ni, Fe, S and P content of ferronickel were taken into account. The results showed that Ni-containing ferronickel from a laterite with 0.88 wt. % Ni during the process in the rotating furnace is characterized by different reactions which have been verified by XRD diffraction.

Molecular dynamics simulation, spectroscopy characterization and properties testing of high-titanium CaO-SiO2-10 wt%MgO-13 wt%Al2O3-4 wt%FeO-40 wt%TiO2 slag melts

In this study, the effect of the CaO/SiO2 mass ratio on the viscosity, free running temperature, electrical conductivity and structure of high-titanium CaO-SiO2-10 wt%MgO-13 wt%Al2O3-4 wt%FeO-40 wt%TiO2 slag was investigated. The results revealed that viscosity and free running temperature monotonically decreased with an increasing CaO/SiO2 ratio from 0.1 to 0.8, whereas the electrical conductivity followed a trend of first increasing, then decreasing, and ultimately increasing again. XRD analysis revealed only a small amount of Ti-related phases in the quenched slag. This ensured that the high-temperature state structure of the slag was largely preserved. Molecular dynamics simulations, FTIR, and Raman results indicated that Ti-based structural units predominated in the slag. With an increasing CaO/SiO2 ratio, the [SiO4] tetrahedral and Ti-based structures progressively simplified, while the [AlO4] tetrahedral and Si-O-Al structures showed a tendency of complexity followed by simplicity. However, the overall degree of polymerization of the slag decreased, leading to the viscosity reduction. The degree of polymerization and the migration capacity of ions and electrons together contributed to complex changes in electrical conductivity. A comprehensive analysis indicated that the slag composition with a CaO/SiO2 mass ratio of 0.4 is more favorable for the smelting of vanadium-titanium magnetite in the pre-reduction electric furnace process.

Green Ironmaking at Higher H2 Pressure: Reduction Kinetics and Microstructure Formation During Hydrogen-Based Direct Reduction of Hematite Pellets

Hydrogen-based direct reduction (HyDR) of iron ores has attracted immense attention and is considered a forerunner technology for sustainable ironmaking. It has a high potential to mitigate CO2 emissions in the steel industry, which accounts today for ~ 8–10% of all global CO2 emissions. Direct reduction produces highly porous sponge iron via natural-gas-based or gasified-coal-based reducing agents that contain hydrogen and organic molecules. Commercial technologies usually operate at elevated pressure, e.g., the MIDREX process at 2 bar and the HyL/Energiron process at 6–8 bar. However, the impact of H2 pressure on reduction kinetics and microstructure evolution of hematite pellets during hydrogen-based direct reduction has not been well understood. Here, we present a study about the influence of H2 pressure on the reduction kinetics of hematite pellets with pure H2 at 700 °C at various pressures, i.e., 1, 10, and 100 bar under static gas exposure, and 1.3 and 50 bar under dynamic gas exposure. The microstructure of the reduced pellets was characterized by combining X-ray diffraction and scanning electron microscopy equipped with electron backscatter diffraction. The results provide new insights into the critical role of H2 pressure in the hydrogen-based direct reduction process and establish a direction for future furnace design and process optimization.Graphical

Effects of Metallization Degree of DRI on the Yield and CO2 Emission in Reduction Shaft Furnace Process

Effects of Metallization Degree of DRI on the Yield and CO2 Emission in Reduction Shaft Furnace Process

Decarbonizing rotary kiln–induction furnace based sponge iron production

The direct carbon dioxide (CO2) emissions from the iron and steel sector are nearly 7 % of the global CO2 emissions from energy use. India is the world's second-largest producer of steel and the largest sponge iron producer. India produces one-third of the global sponge iron, mostly from rotary kilns using coal as an energy source, resulting in higher energy and emission intensities than the global average. This study evaluates major options for CO2 abatement in the rotary kiln–induction furnace process for steel production. Based on the mass and energy balances of a typical sponge iron plant, this study evaluates the techno-economic potential of nine major decarbonization measures. The proposed decarbonization measures include improved energy efficiency, improved material efficiency, renewable energy use, and fuel substitution. Marginal abatement and green premium curves are generated by incorporating the dependency of different measures. Depending upon the set of options chosen, carbon abatement is in the range of 55.8 %–99.2 %. It is observed that 11.5 %–20.6 % of decarbonization potential can be achieved without any additional cost to the customer. These findings are insightful for policymakers and industry stakeholders and provide a foundation for designing and implementing a net-zero pathway for the sector.

Development and study of a method for controlling anomalous behavior in the blast furnace process

Development and study of a method for controlling anomalous behavior in the blast furnace process

Mechanosynthesis of TaC-WC powders under environmental conditions and their consolidation via electric arc furnace

In this study, tantalum carbide (TaC) was synthesized using an innovative approach that synergistically integrates mechanosynthesis and electric arc furnace processes. By employing high-energy ball-milling (HEBM) for 50 min under environmental conditions, TaC-WC powders were successfully synthesized, using a powder mixture of tantalum and carbon in a 1:1 stoichiometric ratio. This method yielded a composition of 72.5 wt% TaC and 27.5 wt% WC, with an average particle size of 0.7 ± 0.3 μm. The use of an electric arc furnace led to the fabrication of a highly dense material with a relative density above 98%. Notably, WC derived from the mechanical milling material served as an effective sintering aid. x-ray photoelectron Spectroscopy (XPS) results indicated the formation of metal oxides on the surface of the sample, and despite the presence of these oxides, the density of the material remained uncompromised. Furthermore, x-ray diffraction (XRD) analysis after the electric arc furnace treatment demonstrated the preservation of the TaC and WC phases. Mechanical properties, including Vickers hardness, Young’s modulus and fracture toughness were 22.8 ± 0.5 GPa under an applied load of 9.8 N, 539 GPa and 6.6 MPa m1/2, respectively. The results underscore a novel and efficient synthesis route for TaC-WC with enhanced mechanical properties and high density, which are crucial aspects for applications in ultra-high temperature ceramics.