Direct Reduced Iron Research Articles

Red mud as a green dephosphorization agent: Co-reduction with high phosphorus oolitic hematite for iron extraction and dephosphorization

The large utilization of red mud (RM) presents many challenges due to its high alkalinity, which is attributed to the presence of CaO and Na2O. High phosphorus oolitic hematite (HPOH) is a typical refractory ore for Fe and P separation. During the direct reduction of HPOH to produce direct reduced iron (DRI) and achieve simultaneous dephosphorization, sodium or calcium salts are typically added as dephosphorization agents. This study investigated the feasibility of using RM as a green dephosphorization agent. Co-reduction of RM with HPOH was conducted to prepare DRI. By adding 60 % RM and using a reductant dosage of 17 %, a DRI with 90.89 % Fe and 0.095 % P was obtained. The corresponding total iron recovery was 87.79 %. This indicated that the addition of RM facilitated effective simultaneous iron extraction and dephosphorization. The co-reduction mechanisms were analyzed using X-ray diffraction (XRD), thermodynamic analysis, and scanning electron microscopy combined with energy dispersive spectroscopy (SEM–EDS). In the absence of RM, the reduction of fluoroapatite occured, leading to the incorporation of P into metallic iron. However, with adding RM, albite and anorthite were generated, hindering the reduction behavior of fluoroapatite and reducing P content in DRI. Thus, RM effectively served as a green dephosphorization agent in the co-reduction process.

Dephosphorization study on hydrogen reduction-melting separation of high-phosphorus oolitic hematite

In order to clarify the dephosphorization mechanism of DRI (Direct Reduced Iron) derived from hydrogen reduced high-phosphorus iron ore during the electric arc furnace melting process, slag was prepared using reagent-grade powder based on the gangue mineral composition of high-phosphorus oolitic hematite. By incorporating varying amounts of CaO, FeOx, and reduced iron powder, experiments simulating the dephosphorization of melting separation slag from DRI with different basicity and metallization rates were conducted at 1873 K. The results show that phosphorus in the iron primarily exists in the form of Fe–P–O spherical slag inclusions and FexP, while in the slag, phosphorus mainly resides within the silicate phases. As the amount of CaO added increases, there is a significant decrease in the phosphorus content within the slag inclusions, and the P-containing compounds in the iron gradually shift from FexP and Fe3(PO4)2 to FeO. As the dephosphorization capacity of the slag increases, the distribution of phosphorus-rich phases in the rapidly cooled slag becomes more extensive. When the basicity increases to 3, the phosphorus-rich phases in the slag transition to 2CaO·SiO2 and 3CaO·SiO2. When the basicity is fixed at 2.5, regulating the metallization rate can control the FeOx content in the molten slag, thereby enhancing the dephosphorization ability of slag. The results show that under conditions of a DRI basicity of 2.5 and a metallization rate of 85%, slag/metal separation can produce low-phosphorus iron with 0.022 wt% P, achieving a dephosphorization rate exceeding 95%.

Making quality agglomerates using lean iron ores for sustainable iron-making

For sustainable iron making and hassle-free operation of large blast furnaces (BF) and direct reduced iron (DRI) units, a more prepared burden in the form of good quality agglomerates is required. However, the situation is becoming more and more challenging owing to the faster depletion of high-grade iron ore, increased fines generation due to mechanized mining, wide variations in chemistry & mineral characteristics, high content of gangue minerals, and poor liberation characteristics. The growing demand for steel vis-à-vis iron ores has necessitated the utilizationof low-grade iron ores for steel production. The challenges lie in the economic extraction of lean ores and their conversion into quality agglomerates for use in iron making. The utilization of low-grade iron ores has assumed greater significance for the optimal utilization of natural resources and the sustainability of the steel industry. Thebeneficiated concentrate of BHQ iron ore from the Sandur Schist belt is used for the pellets. Green green pellets with 1.21 kg/pellet GCS and drop strength of 12 drop number were producedat an optimum binder of 1.2% and moisture of 9.5%. Induration of green pellets at a firing temperature of 1300 °C has resulted in adequate pellet properties of 237 kg/pellet of CCS, 91.87% TI, 7.41% RDI, and 22.56% porosity. An attempt is made to produce pellets suitable for iron making by optimizing various raw materials and operating parameters.This will reduce dependency on high-grade ores and effectively utilize low-grade iron ore to produce good-qualityiron-making pellets.

A Study of the Possibility of Producing Annealed and Metallized Pellets from Titanomagnetite Concentrate.

The current intensive development of steelmaking is being impeded by a scarcity of pure scrap. The potential to replace pure scrap with metallized raw materials that are naturally alloyed with vanadium and titanium, such as annealed unfluxed titanomagnetite pellets, could facilitate the achievement of key objectives in metallurgical development, particularly in the smelting of electric steel. The objective of this research was to produce annealed and metallized pellets from titanomagnetite concentrate under laboratory conditions, with the intention of further processing them as a commercial product in a blast furnace or as an intermediate product for the production of hot briquetted iron (HBI). The results demonstrate that pellets derived from titanomagnetite concentrate exhibit sufficient compressive strength (up to 300 kg/pellet) and a degree of metallization exceeding 90%, which aligns with the requirements for electric steelmaking. The suitability of pellets derived from titanomagnetite concentrate for use in both blast furnaces and metallization processes has been corroborated.

CFD Modeling of HBI/scrap Melting in Industrial EAF and the Impact of Charge Layering on Melting Performance.

The melting of scrap and hot briquetted iron (HBI) in an AC electric arc furnace (EAF) is simulated by an advanced 3D computational fluid dynamics (CFD) model that captures the arc heating, the scrap/HBI melting process, and the solid collapse mechanisms. The CFD model is used to simulate a scenario where charge layering and EAF power profiles are provided by a real EAF operation. CFD simulation of the EAF operation shows proper prediction of the charge melting when compared with standard industry practice. Namely, the CFD model predicts a 32.5%/67.5% ratio of solid/liquid steel at the beginning of refining, which approaches the 30%/70% ratio used in standard practice. Based on this prediction, the melting rate in the CFD results differs by 8.3% from actual EAF operation. The impact of charge layering on melting is also investigated. CFD results show that distributing charge material into a greater number of layers in the first bucket (10 layers as compared to 4) enhances the melting rate by 12%. However, including dense material at the bottom of the furnace deteriorates melting performance, reducing the impact of the number of layers of the charge. The CFD platform can be used to optimize the use of HBI/scrap in real EAF operations and to determine best recipe practices.

Decarbonization pathways analysis and recommendations in the green steel supply chain of a typical steel end user-automotive industry

China's automotive industry, the world's largest producer and consumer, has reached a crucial stage in its transition from rapid expansion to high-quality and low-carbon development. Considering the decarbonization of the whole automotive industry, in addition to reducing the CO2 emissions from fuel supply and exhaust pipes, which account for 65–80 % of the total value chain CO2 emissions, the automotive industry should also accelerate the decarbonization of raw materials, which contribute to 18–22 % of these CO2 emissions. Many automotive manufacturers are collaborating with steel producers on green steel initiatives due to the high CO2 emissions from steel production, the integrated nature of the steel supply chain, and the need for early planning in low-carbon steel production routes transformation. To clarify the carbon emission characteristic of the automotive steel supply chain, this research establishes a mathematical method for calculating cradle-to-gate carbon footprint of automotive steel product based on BF (Blast furnace)-BOF (Basic oxygen furnace), Scrap-EAF (Electric arc furnace), and DRI (Direct reduced iron)-EAF steel production routes. The cradle-to-gate carbon footprints of BF-BOF, Scrap-EAF, and DRI-EAF steel production routes are 1711.84 kgCO2/t-sp (steel product), 916.39 kgCO2/t-sp, and 2738.53 kgCO2/t-sp. A projection of CO2 emissions in automotive steel supply chain from 2020 to 2060 has been investigated, taking into account production structure adjustment, scrap recycling, and low-carbon electricity adoption, as well as the demand for automotive steel products. Projections from 2020 to 2060 indicate that the CO2 emission intensity of the automotive steel supply chain will decrease by 28.25 % by 2030 and 93.99 % by 2060, with total emissions dropping by 28.47 % and 96.92 %, respectively. This research identifies effective decarbonization measures in the automotive steel supply chain, including internal and end-of-life (EOL) steel scrap recycling, which offer significant CO2 emissions reduction without increased costs, demonstrating high cost-effectiveness. In a word, this research provides a technical framework and data foundation for decarbonizing the automotive steel supply chain.

Calcium Carbonate as Dephosphorization Agent in Direct Reduction Roasting of High-Phosphorus Oolitic Iron Ore: Reaction Behavior, Iron Recovery, and Dephosphorization Mechanism

Calcium carbonate, renowned for its affordability and potent dephosphorization capabilities, finds widespread use as a dephosphorization agent in the direct reduction roasting of high-phosphorus oolitic hematite (HPOIO). However, its precise impact on iron recovery and the dephosphorization of iron minerals with phosphorus within HPOIO, particularly the mineral transformation rule and dephosphorization mechanism, remains inadequately understood. This study delves into the nuanced effects of calcium carbonate on iron recovery and dephosphorization through direct reduction roasting and magnetic separation. A direct reduction iron (DRI) boasting 95.57% iron content, 93.94% iron recovery, 0.08% phosphorus content, and an impressive 92.08% dephosphorization is achieved. This study underscores how the addition of calcium carbonate facilitates the generation of apatite from phosphorus in iron minerals and catalyzes the formation of gehlenite by reacting with silicon dioxide and alumina, inhibiting apatite reduction. Furthermore, it increases the liquid phase, enhancing the dissociation of metallic iron monomers during the grinding procedure, thus facilitating efficient dephosphorization.

Effect of location on green steel production using Australian resources

Hydrogen is being increasingly considered as a chemical feedstock and energy storage vector within the iron and steel industry. This study compares the cost and CO2 emissions associated with green steel production as a function of location for the components in its supply chain between Australia (Pilbara) and China (Beijing). Results are benchmarked against a new facility using conventional coal-based technology, producing Hot Rolled Coil (HRC) steel in China as a common final product. Green steel production in Australia using hydrogen is considerably cheaper and presents lower emissions than exporting the hydrogen and iron ore to China for subsequent processing. Costs are comparable when intermediate Hot Briquetted Iron (HBI) is exported but with increased emissions. However, utilising blue hydrogen produced in China is the most immediately dispatchable with a 35% reduction in CO2 emissions and an increase in levelised cost of steel (LCOS) of only 11% relative to current practice.

Emission Impacts of Direct Reduced Iron‐Ore Processing Systems: A Systems Thinking Approach in Case Studies of Canada and Peru

This study presents a novel methodology for quantifying CO2 emissions in direct reduced iron (DRI)‐grade iron‐ore processing plants using system dynamics modeling (SDM) with an emphasis on associated uncertainties. Two plants in Canada and Peru are analyzed, where similar ore grades (34.89% and 39.10%) but different ore types (hematite and magnetite) lead to distinct mineral processing systems. By incorporating the breakdown of power grid generation sources, the annual CO2 emissions are quantified, finding significantly higher emissions in Peru (22,241.63 tCO2e ton−1) compared to Canada (2,252.85 tCO2e ton−1). These results highlight the critical impact of local energy grids on emissions, underscoring the need to consider both ore characteristics and regional energy profiles in developing decarbonization strategies. This study offers a structured approach to assessing the CO2 impact of raw materials in low‐carbon steel production. It emphasizes the effect of the spatial distribution of raw materials in the steel‐making process. The analysis reveals that emissions from the plant in Peru are nearly 10 times higher than those in Canada, highlighting the significant influence of the local energy grid. These results underscore the influence of ore characteristics and regional energy profiles in developing effective decarbonization strategies.

Factors influencing physical and mechanical properties of direct reduced iron ore pellets

Direct Reduction processes for iron ore employing natural gas or hydrogen are becoming more important. Correspondingly, properties of outgoing products are of importance. Degradation of Direct Reduced Iron (DRI) feedstock greatly influences storage, handling, risk of reoxidation, and following melting operations. The focus of this work has been on the physical properties of DRI, and their effect on mechanical properties. Four types of industrially produced DRI having varying metallization, carbon content, structure and apparent porosity have been studied. Three of the selected DRI types have been reduced using natural gas, and one DRI type has been reduced using pure hydrogen. Cold compression strength and tumbling tests are performed. Qualitative analysis of samples before and after mechanical testing is made using SEM and LOM. Results show that total carbon content has a significant influence on overall mechanical strength of DRI. Degradation of samples in tumbling tests is least significant for the hydrogen-reduced – and hence carbon-free – DRI type. The DRI type containing the most carbon (3 wt%) exhibits the most fines generation and lowest compression strength. Furthermore, apparent porosity and fractures formed during reduction have a small though not as significant impact as carbon content on mechanical properties.

Development and Application of Hydrogen-Based Direct Reduction Iron Process

The conventional iron and steel industry (ISI), driven by coal utilization as its predominant feedstock, constitutes a substantial source of greenhouse gas emissions. Hydrogen metallurgy presents the opportunity to mitigate carbon emissions in ISI from the origin. Among hydrogen metallurgical approaches, the hydrogen-based direct reduction iron (H-DRI) process stands out for its substantial carbon reduction capabilities and established technological maturity. The present paper provides a comprehensive review of the development and application surrounding the H-DRI process. Firstly, the main chemical reactions of H-DRI and the relevant important parameters are introduced. Subsequently, an overview is provided of several prominent H-DRI processes, including HYL, Midrex, Midrex-H2®, HYL-III, HYL-ZR, BL, and Finmet, elucidating their characteristics through comparative analysis. Moreover, some research results of H-DRI process optimization are summarized. Leveraging insights garnered from globally representative projects exemplifying the industrial deployment of H-DRI technology in recent years, the trajectory of and prospective trends for industrial development in the field of H-DRI processes are explored. Further, prevailing challenges and impediments encountered in the adoption of H-DRI processes are identified, culminating in strategic recommendations tailored towards fostering future advancements. In the long term, the H-DRI process is expected to become a key path to achieve ISI cleaner production.

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.

Low‐carbon economic schedule of the H2DRI‐EAF steel plant integrated with a power‐to‐hydrogen system driven by blue hydrogen and green hydrogen

AbstractHydrogen direct reduction iron coupled with electronic arc furnace (H2DRI‐EAF) technology, as an important technology for decarbonisation in the iron and steel industry, has the advantages of high electrification and low carbon emissions. However, the large demand for hydrogen in this technology relies significantly on the production of electrolytic hydrogen, leading to a substantial increase in power consumption in the steel production process. Moreover, the use of an unclean power source in electrolytic hydrogen production leads to increases in indirect carbon emissions, reducing the low‐carbon attributes of the technology. This study investigates the integrated flexible operation mode of a steel plant. An illustrating method is utilised for modelling the entire steel production process and power to hydrogen (PtH2) process in detail for the H2DRI‐EAF steel plant, which includes natural gas, photovoltaic, wind power self‐provided power plants, and carbon capture and storage (CCS) systems. A mixed integer linear programming (MILP) model is developed for the comprehensive scheduling of the steel mill. The results of the case studies indicate that by reliably integrating the production of renewable energy and natural gas power plants, the PtH2 system can fully consume the renewable energy output while ensuring the smooth progress of steel production and maximising the reduction of carbon emissions from hydrogen production and the total cost of steel production.

Reoxidation Behavior of the Direct Reduced Iron and Hot Briquetted Iron during Handling and Their Integration into Electric Arc Furnace Steelmaking: A Review

This paper studies the integration of direct reduced iron (DRI) and hot briquetted iron (HBI) into the steelmaking process via an electric arc furnace (EAF). Considering a variety of DRI production techniques distinguished by different reactor types, this paper provides a comparative overview of the current state. It delves into significant challenges, such as the susceptibility of DRI to reoxidation and the necessity of thorough handling to maintain its quality. The effectiveness of several reoxidation mitigation strategies, including the application of thin oxide layers, briquetting, various coatings, and nitride formation in ammonia-based reduction processes, is evaluated. Most existing studies have primarily focused on the reoxidation of DRI rather than on HBI, despite the fact that HBI may undergo reoxidation. The importance of DRI/HBI in offering an alternative to the integrated steelmaking route is highlighted, focusing on how it changes the EAF process compared to those for melting scrap. This paper also identifies several research prospects for further DRI/HBI applications in steel production.

Renewable Electricity and Green Hydrogen Integration for Decarbonization of “Hard-to-Abate” Industrial Sectors

This paper investigates hydrogen’s potential to accelerate the energy transition in hard-to-abate sectors, such as steel, petrochemicals, glass, cement, and paper. The goal is to assess how hydrogen, produced from renewable sources, can foster both industrial decarbonization and the expansion of renewable energy installations, especially solar and wind. Hydrogen’s dual role as a fuel and a chemical agent for process innovation is explored, with a focus on its ability to enhance energy efficiency and reduce CO2 emissions. Integrating hydrogen with continuous industrial processes minimizes the need for energy storage, making it a more efficient solution. Advances in electrolysis, achieving efficiencies up to 60%, and storage methods, consuming about 10% of stored energy for compression, are discussed. Specifically, in the steel sector, hydrogen can replace carbon as a reductant in the direct reduced iron (DRI) process, which accounts for around 7% of global steel production. A next-generation DRI plant producing one million tons of steel annually would require approximately 3200 MW of photovoltaic capacity to integrate hydrogen effectively. This study also discusses hydrogen’s role as a co-fuel in steel furnaces. Quantitative analyses show that to support typical industrial plants, hydrogen facilities of several hundred to a few thousand MW are necessary. “Virtual” power plants integrating with both the electrical grid and energy-intensive systems are proposed highlighting hydrogen’s critical role in industrial decarbonization and renewable energy growth.

The performance and charge behaviour in melter/smelter for the production of hot metal in hydrogen DRI-based steelmaking

Direct reduced iron (DRI)-based steelmaking requires high-grade iron ore (Fe > 65 wt-%). However, a swift decline in ore grade has forced steelmakers to use lower-grade ores for DRI making, creating challenges in subsequent processes dealing with high gangue content for steelmaking. Hence, an intermediate melting/smelting furnace has been proposed to treat high gangue content from the DRI before transferring hot metal into an electric arc furnace (EAF)/basic oxygen furnace (BOF) for steelmaking. This study investigates and models the performance and charge behaviour in a melter/smelter with respect to the gangue content, DRI carbon content and temperature. The results showed that the specific energy consumption (SEC) and off-gas production increase with increasing temperature, carbon in DRI and gangue content. At 90 wt-% metallisation ratio (MR) using the lowest-grade ore (gangue 16 wt-%), the SEC at 1300 °C was calculated to be 706 kWh/tHM compared to 850 kWh/tHM at 1600 °C using 3.5 wt-% carbon. The MR is predicted to profoundly impact the SEC, as the increasing MR decreases the SEC markedly. At 90 wt-% MR, the SEC using the lowest-grade ore was 805 kWh/tHM, decreasing to 684 kWh/tHM using 100 wt-%MR. Increasing MR, carbon in DRI and temperature decreases slag production consistently while increasing with the increasing gangue. Using hot DRI onsite is predicted to significantly reduce the SEC compared to cold DRI. Overall, the energy demand from cold DRI is predicted to be 120 kWh/tHM higher than hot DRI. Increasing the scrap-to-DRI ratio is predicted to decrease the energy demand, that is, every 1.0 wt-% increase in scrap decreases the SEC by 2.5 kWh/tHM.

A Coupled CFD-DEM Approach to Model Reactive Granular Beds

Packed and moving bed reactors are widely used in process industry to process granular material. Shaft furnaces are one example of this. Due to their counterflow layout, a high thermal efficiency can be achieved. Shaft furnaces have a wide range of length and time scales that makes them challenging to model. Geometric details, like injection nozzles, are smaller than the particle size, which need a computationally highly expensive resolved Discrete Element Method (DEM) approach. To overcome this problem, a computing technique called Volume Fraction Smoother (VFS) was developed. Since the time scales in those systems reach from milliseconds for the particle collisions to hours of process time, the process time scale must be separated to model a quasi-steady state with reasonable computing time. For this, the Time Scale Splitting Method (TSSM) was introduced. This method was also adapted to model the self-heating behaviour of direct reduced iron (DRI).

The Melting Behavior of Hydrogen Direct Reduced Iron in Molten Steel and Slag: An Integrated Computational and Experimental Study

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.

Techno-economic analysis of integrated MIDREX process with CO2 capture and storage: Evaluating sustainability and viability for iron production

This study offers a comprehensive evaluation of integrating carbon capture and storage (CCS) technology with the Midrex process for direct reduced iron (DRI) production. Employing rigorous simulation and validation against real plant data, we assess the impact of CCS integration on energy consumption, CO2 emissions, and economic feasibility. Our findings reveal a slight increase in energy consumption alongside a substantial reduction in CO2 emissions, with the cost of CO2 avoidance remaining competitive. Sensitivity analysis demonstrates the resilience of the proposed integration to market fluctuations. The findings of our study highlight the possibilities of integrating CCS with the Midrex process to address environmental issues and maintain economic sustainability in the iron manufacturing industry.

Techno-economic study of chimneyless electric arc furnace plants for the coproduction of steel and of electricity, hydrogen, or methanol

Electric arc furnace (EAF) is the most common technology for steel production from steel scrap. Although the input energy is mostly constituted by electricity, significant amounts of carbon dioxide are emitted with the exhaust gases, most of which are classifiable as process-related. The main goal of this study is to perform a techno-economic analysis of chimneyless electric arc furnace plants, fed by either scrap or direct reduced iron (DRI), and able to coproduce steel as well as electricity, hydrogen, or methanol. Several plant configurations are investigated, featuring different combinations of oxy-postcombustion, carbon capture, carbon monoxide-rich gas recovery, hydrogen or syngas production by high-temperature electrolysis or coelectrolysis, and methanol synthesis. These configurations are also characterized by decreased false air leakage and by heat recovery for steam production. Results show that all cases allow achieving a substantial reduction of direct carbon dioxide emissions, close to 99% compared to the unabated conditions. From an economic perspective, in a long-term scenario, the internal rate of return is always above 8%, and up to 73% for the DRI-fed case. However, in a short-term scenario, only cases with sole power production are economically viable. Hydrogen and methanol are competitive with market prices only for low electricity costs. In a higher electricity cost scenario, the case of carbon capture and storage is more competitive than the case of carbon capture and utilization. With an electricity cost of 100 €/MWh, a steel premium of 10–40 €/t allows to reach economic feasibility if methanol or hydrogen selling prices are in line with current market conditions. In general, the configurations with DRI-fed furnaces obtain more favorable economic performance than scrap-fed ones. The competitiveness of sole electricity, hydrogen or methanol production configurations depends on the case study and on the future market prices.