Search Results (37)

This study aims to enhance fundamental research on the reaction behavior between ferric oxide and H₂–CO gas mixtures and to provide theoretical support for optimizing the injection of hydrogen-containing materials in the ironmaking process. In this study, the ultrafine ferric oxide powder was isothermally reduced with H₂–CO gas mixture at 1023 K–1373 K. The results indicated that when H₂ content is less than 30% at 1023 K, the ferric oxide sample reduced by the H₂–CO gas mixture exhibits a pronounced carbon deposition phenomenon during the reduction stage. The gas reactant composition had a relatively large influence on the reaction rate at the third stage of the reduction reaction (FeO → Fe). Assuming the single-step nucleation assumption theory together with kinetic experimental data, the relationship between the average reaction rate and the gas composition of the H₂–CO gas mixture was established for the FeO reduction stage. In addition, the apparent activation energy of the reduction reaction was generally in the range of 20–45 kJ/mol, indicating that the possible rate-controlling step was combined gas diffusion and interfacial gas–solid chemical reaction. Full article

The direct reduction of iron ore by hydrogen is a serious candidate for reducing greenhouse gas emissions in the iron and steelmaking industry by replacing traditional blast furnace technology. The reduction kinetics are key to this process. The present paper reports an extensive parametric study of the reduction of iron ore pellets with hydrogen that combines both experiments and modeling. A new model (modified grainy pellet model) was developed on the basis of the grainy pellet concept, the law of additive reaction times and the evolution of gas composition. The chemical kinetic constants of the three-step reduction reaction were determined from isothermal thermogravimetry experiments in the 600–900 °C temperature range. The model was then validated against laboratory-scale fixed-bed experimental results. A comparison with the experimental thermogravimetry results for a broad range of operating parameters shows the robustness of the model. The effects of temperature, gas dilution, gas flow rate, water content, pellet size, pressure, porosity, tortuosity, and specific surface area were investigated. The temperature, pellet size, pressure, gas composition and, particularly, the water content and gas flow rate have major influences on the reaction rate, in contrast to the initial porosity and specific surface area. Full article

The production of iron and steel plays a significant role in the anthropogenic carbon footprint, accounting for 7% of global GHG emissions. In the context of CO₂ mitigation, the steelmaking industry is looking to potentially replace traditional carbon-based ironmaking processes with hydrogen-based direct reduction of iron ore in shaft furnaces. Before industrialization, detailed modeling and parametric studies were needed to determine the proper operating parameters of this promising technology. The modeling approach selected here was to complement REDUCTOR, a detailed finite-volume model of the shaft furnace, which can simulate the gas and solid flows, heat transfers and reaction kinetics throughout the reactor, with an extension that describes the whole gas circuit of the direct reduction plant, including the top gas recycling set up and the fresh hydrogen production. Innovative strategies (such as the redirection of part of the bustle gas to a cooling inlet, the use of high nitrogen content in the gas, and the introduction of a hot solid burden) were investigated, and their effects on furnace operation (gas utilization degree and total energy consumption) were studied with a constant metallization target of 94%. It has also been demonstrated that complete metallization can be achieved at little expense. These strategies can improve the thermochemical state of the furnace and lead to different energy requirements. Full article

The U.S. ironmaking sector plays a key role in global greenhouse gas emissions, mainly due to long-standing practices such as blast furnaces (BFs) and direct reduction (DR). In this work, we develop a new mathematical approach to estimate future CO₂ emissions from the U.S. ironmaking industry through 2050. Our approach uses historical data from 2005 to 2021 and incorporates economic and energy use indicators to explore how emissions might change over time. According to our results, unless significant technological improvements and stronger energy policies are implemented, the industry is likely to continue producing large amounts of CO₂. These findings highlight the pressing need to adopt cleaner alternatives—such as hydrogen-based direct reduction—to help meet international climate goals. Supporting the transition to low-emission technologies contributes to broader efforts in sustainable industrial development and long-term climate resilience. Full article

The iron and steel industry is a major emitter of carbon. In the context of China’s dual-carbon goals, hydrogen-based reduction ironmaking technology has garnered unprecedented attention. It is considered a crucial approach to reducing carbon dioxide emissions in the steel sector and facilitating the realization of carbon neutrality. This work conducted isothermal thermogravimetric analysis on limonite ore in a N₂/H₂ atmosphere. The influences of reduction temperature, particle size, and hydrogen partial pressure on the hydrogen reduction reaction process of limonite were investigated. Based on the principles of isothermal thermal analysis kinetics and the unreacted core model for flat-plate particles, the mechanism function and kinetic parameters for the reduction of limonite particles were determined. The research results show that the hydrogen reduction process of limonite ore is influenced by multiple factors, including temperature, hydrogen partial pressure, and particle size. Increasing the reduction temperature and hydrogen partial pressure can significantly speed up the reduction reaction rate and enhance the degree of reduction. The kinetic parameters for the hydrogen reduction of limonite particles were obtained as follows: the reaction activation energy was 44.738 kJ·mol⁻¹, the pre-exponential factor was 31.438 m·s⁻¹, and the rate constant for the hydrogen reduction of limonite was $k=31.438\times e^{-{\displaystyle \frac{44.738\times 1000}{RT}}}\mathrm{m}\cdot {\mathrm{s}}^{-1}$. In addition, contour maps were plotted to predict the reaction time and reaction temperature required for a complete reduction of limonite particles of different sizes to iron (Fe) particles under varying hydrogen partial pressures. The research findings can serve as a scientific basis for optimizing hydrogen-based reduction ironmaking technology in the iron and steel industry and achieving carbon neutrality goals. Full article

The extensive use of coal in the steel metallurgy sector has resulted in significant greenhouse gas emissions. Hydrogen-rich gases have been introduced to partially replace coal in the blast furnace reduction process to mitigate this issue. This research explores using abundant coalbed methane (CBM) resources near steel plants for metallurgical applications. Addressing the challenge of determining optimal process parameters in hydrogen-rich blast furnace smelting, this project first develops an energy and mass balance model for the hydrogen-rich blast furnace, providing a foundation for process analysis. Using this model, the substitution ratio and oxygen enrichment rate of the blast furnace are calculated under varying preheating temperatures of coalbed methane. Additionally, this study assesses carbon dioxide emission patterns based on the elemental balance principle, emphasizing the potential of coalbed methane to reduce carbon emissions and support low-carbon metallurgical development. Full article

Against the backdrop of global energy crises and climate change, the iron and steel industry, as a typical high energy consumption and high-emission sector, faces rigid constraints for energy conservation and emission reduction. This paper systematically reviews the research progress and application effects of energy-saving technologies across the entire steel production chain, including coking, sintering, ironmaking, steelmaking, continuous casting, and rolling processes. Studies reveal that technologies such as coal moisture control (CMC) and coke dry quenching (CDQ) significantly improve energy utilization efficiency in the coking process. In sintering, thick-layer sintering and flue gas recirculation (FGR) technologies reduce fuel consumption while enhancing sintered ore performance. In ironmaking, high-efficiency pulverized coal injection (PCI) and hydrogen-based fuel injection effectively lower coke ratios and carbon emissions. Integrated and intelligent innovations in continuous casting and rolling processes (e.g., endless strip production, ESP) substantially reduce energy consumption. Furthermore, the system energy conservation theory, through energy cascade utilization and full-process optimization, drives dual reductions in comprehensive energy consumption and carbon emission intensity. The study emphasizes that future advancements must integrate hydrogen metallurgy, digitalization, and multi-energy synergy to steer the industry toward green, high-efficiency, and low-carbon transformation, providing technical support for China’s “Dual Carbon” goals. Full article

Iron smelting is one of the primary sources of carbon emissions. The development of low-carbon ironmaking technologies is essential for the iron and steel industry to realize the “dual carbon” ambition. Hydrogen-based flash ironmaking technology eliminates traditional pretreatment steps such as sintering, pelletizing, and coking while using hydrogen as a reducing agent, significantly reducing carbon emissions. In the present work, a computational fluid dynamics approach is employed to conduct an in-depth analysis of the radiative properties inside the reaction shaft of a flash smelting furnace. The results illustrate that the lowest gas absorption coefficient and volumetric absorption radiation along the radial direction appear at y = 2.84 m, with the values of 0.085 m⁻¹ and 89,364.6 W/m³, respectively, whereas the largest values for these two variables in the axial direction can be obtained at h = 6.14 m with values of 0.128 m⁻¹ and 132,841.11 W/m³. The reduced incident radiation intensity under case 1’s condition led to distinct differences in the radiative temperature compared to the other four cases. The spatial distributions of the particle absorption and scattering coefficients exhibit excellent consistency. The thermal conductivities of all investigated cases depict similar trends along both the axial and radial directions. Volumetric emissive radiation presents a non-linear trend of first increasing and then decreasing, followed by the rise as the height decreases. This study highlights the critical role of hydrogen-based flash ironmaking technology in reducing carbon emissions and provides valuable insights into the radiative characteristics of its reaction shaft under different operating conditions. Full article

Charging biochar composite briquettes (BCBs) and the injection of hydrogen-rich gas into the blast furnace (BF) are two efficient methods for reducing CO₂ emission in BF ironmaking. This study investigated the reaction behavior of BCBs under a hydrogen-rich atmosphere to explore the potential combination of these two methods for enhanced CO₂ emission reduction efficiency in the BF. The employed BCB had a chemical composition of 52.57 wt.% Fe₃O₄, 24.54 wt.% FeO, 0.98 wt.% Fe, 13.16 wt.% C, and 8.75 wt.% gangue. Isothermal BCB reaction tests were conducted using a custom-design thermogravimetric device under temperatures ranging from 1173 K to 1373 K and under an atmosphere of N₂-H₂ with a H₂ content from 25 vol.% to 75 vol.%. A mathematical model was developed for the kinetics of the BCB reaction behavior under the H₂-N₂ atmosphere. Results showed that the developed model was adequate in predicting the reaction behavior of BCB. Under an atmosphere of 50 vol.% H₂-N₂, increasing the temperature from 1173 K to 1373 K resulted in a decrease in the fraction of iron-oxide oxygen removed by hydrogen from 62% to 26% and an increase in the fraction removed by biochar from 29% to 72%, indicating that hydrogen is the primary reducing agent under low temperatures, whereas, under high temperatures, biochar plays a more significant role. Under a constant temperature of 1273 K, increasing the H₂ content in the atmosphere from 25 vol.% to 75 vol.% led to an increase in the fraction of iron-oxide oxygen removed by hydrogen from 37% to 45%, and a decrease in the fraction removed by biochar from 57% to 53%, suggesting that a higher H₂ content enhances the iron oxide reduction by hydrogen but has little impact on the reduction by biochar. In the reaction process, the main products were CO and H₂O, the iron oxide reduction occurred more rapidly near the center than near the surface, whereas the gasification of biochar followed the opposite trend. The structural transformation of the BCB progressed from sinter iron oxides into the metallic iron network in the reaction. Full article

Biomass ironmaking is crucial for carbon reduction in the ironmaking industry. To understand this process better, the iron production capacity and energy requirements of biomass were studied. A thermodynamic equilibrium model and energy consumption model for the biomass and iron oxide reduction system at 100–1300 °C was established by the minimum free Gibbs energy method. The effects of factors such as biomass type, temperature, and initial amount of iron oxide on the system were analyzed. The research results indicated that the maximum ironmaking capacity of biomass was determined by the element content of carbon, hydrogen and oxygen in biomass and temperature. The equilibrium H₂/(H₂ + H₂O) and CO/(CO + CO₂) at the maximum iron yield were affected not by the biomass species and element content, but by temperature. The reduction capacity of the ten selected biomass types decreased with a temperature increase from 700 °C to 1300 °C. For the 1 kg of pine sawdust and iron oxide system, the maximum equilibrium state amount of metallic iron was 23.05 mol at 718 °C, and the minimum system energy consumption per ton Fe was 1.16 GJ at 800 °C and 1.18 GJ at 900 °C. These research results will provide a key basis for a deeper understanding of the intrinsic mechanism of biomass ironmaking. Full article

The injection of hydrogen into a blast furnace is a promising technology to fulfill the low-carbon ironmaking purpose. A three-dimensional computational fluid dynamic (CFD) model is developed to investigate the effect of hydrogen injection rate and blast oxygen enrichment rate on the tuyere, raceway, and surrounding coke bed behaviors. It was found that hydrogen injection leads to a higher water vapor volume fraction in the raceway and a higher hydrogen fraction in the coke bed. The magnitude of velocity and temperature near the tuyere only increase slightly due to the cold inlet temperature of hydrogen, which also results in lower coke bed temperature. The volume-averaged temperature decreases from 2146 K to 2129 K when the injection rate increases from 0 to 1000 Nm³/h. Oxygen enrichment rate presents a highly positive correlation with temperature in the raceway and coke bed, water vapor and carbon dioxide volume fraction in the raceway, and pulverized coal burnout rate. Because more carbon participates in the raceway reaction with an increase in oxygen enrichment rate from 0% to 10%, the final carbon monoxide fraction in the coke bed increases from 0.29 to 0.40, and the final hydrogen fraction decreases from 0.15 to 0.13. With the increase in hydrogen injection, the temperature of the raceway and the coke bed decreased slightly. Pulverized coal burnout changes little with the hydrogen injection rate increasing from 500 Nm³/h to 1500 Nm³/h, which is because hydrogen combustion promotes pulverized coal at the front part of the raceway but inhibits it at the end due to the relative lack of oxygen. These results will help better understand the combustion behavior in the tuyere and raceway of the blast furnace with oxygen-rich blast and hydrogen injection. Full article

The reduction of hematite with ammonia is a potentially environmentally friendly method of ironmaking. Previous studies on ammonia reduction of pellets typically involved samples weighing only 2.8 g and lacked detailed activation energy analysis for the ammonia-hydrogen co-reduction of pellets. Therefore, to further investigate the reduction thermodynamics and kinetics of NH₃–H₂ reduction of pellets, this study uses 50 g pellets for reduction experiments. By increasing the pellet mass, the study expands the scope of kinetic research on ammonia reduction of pellets. The results indicate that nitrogen gas produced from ammonia decomposition reduces the equilibrium components of the reducing gas. In the temperature range of 700–850 °C, the formation of iron nitride exhibits a narrow range during ammonia reduction of hematite. In the reduction of 50 g of pellets, the reduction rate using 100% NH₃ is lower than that using a 50% NH₃ and 50% H₂ mixed gas, which is, in turn, slower than using 100% H₂. As temperature increases, the reduction effect of 50% NH₃ and 50% H₂ approaches that of 100% H₂. Among common gas-solid reaction mathematical models, the Phase-boundary-controlled model with the Contracting Cylinder Model is selected as the most plausible mechanistic function. For the reduction of 50 g of pellets, the activation energies for reactions using 100% NH₃, 50% NH₃ and 50% H₂, and 100% H₂ are 65.42, 54.37, and 29.17 kJ/mol, respectively. The decomposition of NH₃ has a negative effect on the reduction of Fe₂O₃. XRD analysis and electron microscopy element line scanning show that Fe₄N is formed during the reduction of Fe₂O₃ with 100% NH₃. The use of a 50% NH₃ and 50% H₂ mixture significantly reduces the formation of Fe₄N during the reduction of the pellets. Full article

Direct reduced iron (DRI) and hot briquetted iron (HBI) are essential feedstocks for tramp element control in the electric arc furnace (EAF). Due to greenhouse gas (GHG) concerns related to CO₂ emissions, hydrogen as a substitute for natural gas and a reductant in DRI production is being widely explored to reduce GHG emissions in ironmaking. This study examines the melting behavior of hydrogen DRI (H-DRI) pellets in the EAF containing low-carbon (0.1 wt.%) molten steel and molten slag. A computational heat transfer model was developed to predict the melting behavior of H-DRI pellets. To validate the model, a set of experimental laboratory simulations was conducted by immersing H-DRI in a molten steel bath and slag. The temperature history at the center of the pellet during melting and the shell thickness at different melting stages were utilized to validate the model. The simulation results agree with the experimental measurements of steel balls and H-DRI in different metallic molten steel and slag baths. Full article

The traditional blast furnace ironmaking process is the most widely used ironmaking process globally, yet it is associated with significant drawbacks, including high energy consumption and carbon emissions. To achieve low-carbon ironmaking, researchers have developed hydrogen ironmaking, which is capable of achieving lower CO₂ emissions. Nevertheless, the distribution behavior of impurities has been less studied in the existing research on hydrogen ironmaking. Therefore, in this study, the factors affecting the slag properties and distribution of impurity elements during hydrogen ironmaking were investigated using FactSage, and smelting experiments were carried out. The results show that temperature has the greatest influence on the distribution behavior of the impurities, and excessively elevated temperatures result in the ingress of a significant quantity of impurities into the reduced iron. Reduced iron with a purity of 98.52% was obtained under the conditions of 10%, 10%, 2%, and 2% ratios of CaO, SiO₂, MgO, and Al₂O₃, respectively, a hydrogen flow rate of 12 mL/min, and a temperature of 1400 °C; Lg L Mg, Lg L Al, Lg L Si, and Lg L Ca were 2.72, 2.41, 3.36, and 2.45, respectively (“L” stands for slag-to-metal ratio). The slag was mainly dominated by the silicate, and the iron was mainly lost in the form of mechanical inclusions in the slag. This study will enrich the basic theory of hydrogen ironmaking and is of great significance for the realization of carbon neutralization. Full article

To reduce pollution and improve the efficiency of coal resource utilization, this study proposed an integrated process for smelting reduction ironmaking and coal gasification. A multi-zone constrained mathematical model, based on heat and mass balance calculations, was developed to predict the energy and material flows required to produce 1 ton of hot metal. Two scenarios were examined: one using pure O₂ as the gasification agent (referred to as the non-hydrogen-rich process) and the other using a combination of pure O₂ and pure steam (referred to as the hydrogen-rich process). In the non-hydrogen rich process, as the PCR (Post Combustion Ratio) varies from 0% to 8%, the total coal consumption, O₂ consumption, and volume of exported gas decrease by 57%, 57% and 53%, respectively. In the hydrogen-rich process, as the H₂ content increases from 30% to 50%, the exported gas volume increases by 38%. The upper limit of H₂ content in the SRV (Smelting Reduction Vessel) off-gas is mainly determined by the PCR, which decreases from 52.7% to 45.2% as the PCR varies from 0% to 8%. The findings of this work can serve as a theoretical basis for further investigation of the new process. Full article