Sustainable Transition Pathways for Steel Manufacturing: Low-Carbon Steelmaking Technologies in Enterprises

1. Introduction

The steel industry, as a major contributor to global industrial carbon emissions (accounting for approximately 7% to 11%) [1,2], is facing the severe challenge of achieving net-zero emissions by 2050 under the framework of the Paris Agreement. Against the backdrop of the deepening of climate change governance, a technological revolution centered on low-carbon smelting has become an inevitable path for industry transformation. Since the 21st century, the international community has successively launched major scientific and technological projects such as ULCOS (Europe, 2004), COURSE50 (Japan, 2008), HYBRIT (Sweden, 2016) [3], SALCOS (Germany, 2019) [4], and ROSIE (USA, 2024), reshaping the traditional smelting model through innovative paths such as hydrogen-based metallurgy, carbon capture, and green energy utilization, demonstrating an accelerating trend of technological iteration.

This article delves into the current status and challenges of carbon emissions and energy consumption in the steel industry’s smelting process. It comprehensively reviews the latest developments in low-carbon smelting technologies worldwide, especially the practices and research achievements in reducing carbon dioxide emissions and improving energy utilization efficiency. The article will focus on analyzing the actual effects of low-carbon smelting technologies applied in industrial enterprises in terms of carbon reduction and energy conservation. Through the summary of advanced technologies and the exploration of future development trends, it aims to provide theoretical basis and technical guidance for the steel industry’s low-carbon transformation, contributing to the realization of sustainable development goals.

Currently, industrial steel production mainly adopts two process routes: one is the long process of blast furnace-converter, which requires the preparation of raw materials through processes such as coking, sintering, and pelletizing, followed by smelting in a blast furnace to obtain molten iron, and finally refining in a converter to produce crude steel; the other is the short process centered on electric arc furnaces, which mainly uses scrap steel as raw materials, and after smelting in an electric furnace, it is refined through equipment such as ladle furnaces to produce steel. It can also use direct reduced iron or molten reduced iron as raw materials, and after smelting in an electric furnace and going through the rolling process, it ultimately forms steel products. As shown in Figure 1, taking the data of 2022 as an example, the global steel industry shows the characteristics of “Asia’s continuous dominance and accelerated green transformation”. The international crude steel production was approximately 1.89 billion tons, and the CO₂ emissions from steel production were about 3.61 billion tons, with energy consumption of approximately 396.7 GJ [5]. Behind the huge figures of carbon emissions and energy consumption lies both challenges and opportunities. Figure 2 shows the proportion of different processes in global crude steel production in 2022 and their carbon emission intensities. Currently, the blast furnace-converter long process still dominates steel production, accounting for about 71% of the global crude steel production, with an average CO₂ emission intensity of 2.33 tons per ton of crude steel during the production process; while the short process of electric arc furnaces accounts for 29%, and its carbon emission intensity varies significantly due to differences in raw materials: the average CO₂ emission intensity of the electric furnace process using direct reduced iron as raw material is 1.37 tons per ton of crude steel, and when using scrap steel as raw material, the emission intensity can be further reduced to 0.68 tons per ton of crude steel [5].

Currently, the primary strategies for controlling excessive CO₂ emissions and reducing energy consumption in the steel industry can be summarized into four approaches:

• Replacing conventional energy sources with clean energy;
• Improving energy utilization efficiency;
• Advancing fundamental research on energy utilization theories;
• Implementing carbon capture and resource utilization [6].

The adoption of clean energy alternatives enables source-level control of carbon emissions by fundamentally reducing CO₂ generation. Carbon capture and resource utilization technologies focus on recovering emitted CO₂ and converting it into valuable resources to minimize atmospheric release. Meanwhile, enhancing energy efficiency and developing foundational energy utilization theories aim to optimize energy consumption processes for better carbon emission management. Collectively, these four strategies address three critical phases of decarbonization: source-level emission reduction, process-level carbon control, and end-of-pipe carbon mitigation [7]. As illustrated in Figure 3, the analysis of green steelmaking pathways systematically integrates these strategies to achieve sustainable production objectives.

2. Decarbonization Pathways for BF-BOF Long-Process Steelmaking

Achieving carbon reduction in the blast furnace-basic oxygen furnace (BF-BOF) long process fundamentally challenges the century-old carbon-based reduction and smelting system. Although technologies such as hydrogen metallurgy and oxygen-enriched combustion provide new pathways for reducing carbon emissions, their application in blast furnaces faces thermodynamic limitations (e.g., temperature, reduction efficiency, and energy balance), sunk costs of existing BF-BOF infrastructure (amounting to hundreds of billions of dollars), and the immaturity of green hydrogen supply systems. These factors collectively create multiple barriers to low-carbon transition in the BF-BOF route. Therefore, the BF-BOF process must ensure steel supply security while gradually transitioning from “carbon metallurgy” to “green metallurgy,” which represents a critical challenge in the global steel industry’s low-carbon revolution.

2.1. Source-Stage Carbon Reduction

The BF-BOF long process dominates global steel production, contributing 71% of crude steel output. However, its high carbon emissions and energy consumption remain key challenges for the industry’s low-carbon transformation. Given the current limitations of electric arc furnace (EAF) short-process steelmaking in achieving large-scale substitution, innovative carbon reduction strategies for BOF processes are crucial. Source-stage carbon reduction focuses on optimizing raw materials, including increasing the use of low-carbon hot metal and enhancing scrap steel consumption. Methods to produce low-carbon hot metal include high-proportion pellet charging, oxygen-enriched injection, full-oxygen smelting, biomass/plastic/hydrogen injection, and blast furnace gas recycling. While many of these technologies remain immature (e.g., pilot technologies shown in Table 1), high-proportion pellet charging is relatively feasible for most enterprises. This study proposes a dual carbon reduction strategy: developing large-proportion pellet-based low-carbon metallurgy to produce low-carbon hot metal and establishing efficient scrap utilization systems to increase scrap ratios. Quantitative analysis shows that each 1% increase in scrap ratio reduces carbon emissions by 16 kg per tonne of steel [8], highlighting the advantages of circular economy. Therefore, exploring the synergy between large-proportion pellet smelting for low-carbon hot metal production and advanced scrap utilization technologies will be critical for achieving deep decarbonization in BOF steelmaking.

2.1.1. Application Case Studies of High-Proportion Pellet Charging in Blast Furnaces

The high-proportion pellet charging technology in blast furnaces significantly reduces fuel consumption and carbon emissions by optimizing raw material quality, adjusting operational parameters, and innovating burden distribution methods. In China, enterprises such as Shougang and Tangsteel have achieved efficient low-carbon production through refined management and process innovation. In the EU and North America, breakthroughs in environmental and economic performance have been realized by leveraging high-quality pellet resources and mature technical systems.

By replacing traditional sinter, high-pellet-ratio smelting has become a critical pathway for low-carbon ironmaking, reducing carbon emissions by 12%~35% (e.g., 35% reduction at SSAB Sweden [17], 18% at Shougang Jingtang [18]) while improving fuel efficiency (e.g., fuel ratios of 430 kg/t at U.S. Great Lakes Steel and 497 kg/t at Kobe Steel Japan). Representative cases include: Shougang Jingtang’s 5,500 m³ blast furnace with a blast kinetic energy of 140 kJ/s, SSAB’s full-pellet smelting process achieving a slag generation rate of 146 kg/t, and Kobe Steel’s coke interlayer charging method reducing pressure differential by 15%. These cases demonstrate innovations in raw material compatibility, operational optimization, and localized resource utilization. A comparative analysis of their technical pathways, emission reduction potential, and limitations is systematically presented in Table 2.

High-proportion pellet smelting reduces carbon emission intensity by 12%~35% (e.g., 25% at Kobe Steel Japan and 35% at SSAB Sweden [17]) while improving fuel efficiency (e.g., a fuel ratio of 430 kg/t at U.S. Great Lakes Steel) and lowering hot metal production costs (e.g., $8/t reduction in the U.S. and €15/t at SSAB). This is achieved through three integrated strategies: high-grade raw materials (SSAB’s pellets with TFe >66.8% [17]), advanced process refinement (Shougang Jingtang’s optimized blast kinetic energy of 140 kJ/s [19]), and slag system optimization (Tangsteel’s MgO/Al₂O₃ ratio control at 0.5~0.55). As a core technology for blast furnace decarbonization, this approach combines high-quality burden materials, innovative processes (e.g., oxygen-enriched injection and hydrogen-based reduction), and operational precision to reduce carbon emissions by 20%~46% per tonne of iron and enhance fuel efficiency by 15%~30%. Simplified slag systems and resource recycling further reduce production costs.

However, challenges remain, including high raw material costs (SSAB’s pellet preparation energy consumption increases by 20%), process instability (Tangsteel’s ±5% fluctuation in pellet RDI [21]), and equipment compatibility limitations (Kobe Steel’s basicity fluctuations of ±0.1 requiring limestone adjustments [22]). Future development requires integrating hydrogen-electricity-pellet hybrid technologies, pelletization processes adaptable to low-grade ores, and intelligent control systems. Supported by advancing carbon pricing mechanisms and growing demand for green steel, high-pellet-ratio smelting is transitioning from pilot demonstrations to global scalability. This technology will serve as a pillar for the steel industry’s transition toward “near-zero carbon” goals, ensuring the sustainable competitiveness of blast furnace ironmaking in the carbon-neutral era.

2.1.2. Application Case Studies of High-Scrap-Ratio Steelmaking

High-scrap-ratio steelmaking, a core pathway for low-carbon transition in the steel industry, significantly reduces reliance on iron ore and coke by increasing scrap steel utilization in raw materials (10%~100%), achieving 6%~78% reduction in carbon emissions per tonne of steel. Its techno-economic feasibility depends on process type (BOF scrap preheating, EAF-based hybrid routes), resource availability (scrap/DRI supply, energy prices), and policy frameworks (carbon tax, green power subsidies). In current mainstream processes, the scrap ratio typically ranges from 10%~25% in conventional BF-BOF routes, while EAF short processes under green electricity support can reach 80%~100%, albeit facing challenges in scrap impurity control (Cu, Sn <0.2%) and preheating costs (50~100 CNY/t).

Table 3 presents global case studies of scrap utilization across different process types, comparing technical configurations, carbon reduction performance, and economic viability.

As outlined in Table 3, high-scrap-ratio steelmaking has become a core pathway in the global steel industry’s low-carbon transformation, achieving carbon reduction and efficiency improvements through process innovation and policy coordination, yet facing multiple challenges. In current technological practices, traditional long-process routes have significantly enhanced efficiency through scrap preheating and multi-process synergy. For instance, Tangsteel increased its BOF scrap ratio to 30%~40% [23,24] by adopting hot metal ladle preheating, full-laddle covering, and dynamic thermal balance models, reducing steelmaking costs by 5.8%. Shougang Jingtang achieved 50% scrap ratio in continuous casting for automotive steel production through dynamic thermal control and plans to test 55%, highlighting the potential of optimizing long-process routes. In electric arc furnace (EAF) processes, the near-zero-carbon EAF technology developed by Prof. Zhu Rong’s team at the University of Science and Technology Beijing integrates wind-solar-storage microgrids and hydrogen burners, reducing green power costs to 0.2~0.3 CNY/kWh (0.03~0.04 USD/kWh) [27], while achieving near-zero process emissions via CO₂ injection for nitrogen control and biomass gas substitution for carbon powder.

The scalability of these technologies still faces dual challenges:material compatibility and energy economics. Impurities in scrap steel, such as copper and tin (e.g., purchased scrap containing 0.3%~0.6% Cu), restrict high-grade steel production, necessitating pretreatment technologies like magnetic separation and eddy current sorting, as well as molten iron denitrification and residual element control. Green power and supplemental heating costs remain critical barriers. Prof. Zhu’s“EAF-energy storage-renewables” microgrid system [27] reduces energy consumption through peak shaving, while hydrogen-based reduction replaces carbon reductants, cutting emissions by 150 kg CO₂ per tonne of steel.

Future advancements require policy-driven and industry-chain collaboration. China’s Steel Industry Standard Conditions (2025 Edition) sets a target of 15% EAF steel share, and carbon taxes (>80 USD/t) combined with green steel certifications will accelerate the transition of BF-BOF capacities. Technology development will focus on three directions: maximizing long-process potential through BOF powder injection to increase dephosphorization rates to 92%~95% and scrap ratios beyond 50%; advancing EAF purification via green power integration and intelligent controls, such as AI algorithms optimizing smelting parameters to reduce waiting time by 5~8 minutes per heat; and integrating hydrogen metallurgy, with projections indicating that full-scrap EAFs will account for 56.1% of production by 2045, complemented by hydrogen-reduction-EAF routes at 17%, forming a “short-process dominant, hydrogen-supplemented” structure. Supported by expanding scrap resources (China’s annual scrap output exceeding 300 million tonnes by 2025) and a global trade network (import tariffs <5%), the steel industry aims to reduce carbon emissions to below 0.2 tonnes CO₂ per tonne of steel by 2060, providing critical support for carbon neutrality goals.

2.2. Process Carbon Control

Driven by global carbon peaking and neutrality goals, the steel industry—as a major carbon emitter—urgently requires technological innovations to achieve dual breakthroughs in process decarbonization and quality enhancement. Long-process steelmaking, characterized by high energy consumption and emissions, has become a critical focus for low-carbon transformation. Process carbon control technologies, serving as the nexus between energy utilization and metallurgical reactions, are evolving from single-factor efficiency optimization to integrated innovations involving multi-medium synergy and full-process dynamic regulation. As shown in Table 4, technologies such as sub-lance/online detection and AI-powered endpoint prediction models are under active development. This study focuses on the more mature BOF bottom-blowing O₂-CO₂-CaO technology, which significantly improves efficiency through process innovation during the core decarbonization stage of BOF operations and has been applied at the industrial scale.

Representing advanced low-carbon metallurgical practices, the BOF bottom-blowing O₂-CO₂-CaO technology optimizes gas medium composition and equipment design, enhancing steel cleanliness and smelting efficiency while enabling in-situ CO₂ resource utilization. By replacing traditional inert gases with CO₂-containing media, this technology reduces slag oxidation and improves dephosphorization rates, achieving 15%~20% lower oxygen consumption and 5%~8% reduction in iron loss compared to conventional methods. Its ability to simultaneously enhance product quality and carbon utilization has positioned it as a strategic priority in global steel technology competition.

The BOF bottom-blowing O₂-CO₂-CaO technology involves the simultaneous injection of oxygen (O₂), carbon dioxide (CO₂), and calcium oxide (CaO) fluxing agents through the bottom of the converter. By enhancing the efficiency of oxidation reactions within the furnace and optimizing atmosphere and temperature control, this technology significantly improves molten steel quality while reducing energy consumption and carbon emissions. The combined use of bottom-blown O₂ and CO₂ not only accelerates the smelting process but also minimizes nitride formation (e.g., TiN, AlN) and harmful gas generation (e.g., NO_x), advancing low-carbon steelmaking technologies. The technical characteristics and emission reduction effects of global industrial applications are systematically analyzed in Table 5, highlighting case studies from leading steel enterprises.

Global implementation of BOF bottom-blowing O₂-CO₂-CaO technology demonstrates that diversified gas injection media and equipment innovations effectively drive the low-carbon transition of the steel industry. HBIS Handan optimized molten bath stirring efficiency through tuyere layout adjustments, achieving a groundbreaking carbon-oxygen product of 0.0026. Ansteel’s patented eccentric gas duct design increased smelting efficiency by 15% while reducing oxygen consumption. Baosteel’s annular-gap swirling device improved steel cleanliness by 20% and significantly reduced dust emissions. ThyssenKrupp in Germany integrated off-gas recycling systems to achieve annual CO₂ reductions of 2 million tonnes, while Nippon Steel in Japan advanced endpoint control technologies, boosting de-sulfurization rates by 10% and lowering final nitrogen content. Notably, JISCO Group’s high-intensity CO₂ injection process with nitrogen-argon switching stabilized endpoint nitrogen content below 20 ppm and pioneered in-situ CO₂ utilization. Despite regional differences in technical focus—China emphasizes equipment innovation, Germany prioritizes system integration, and Japan specializes in endpoint control—all approaches achieved 15%~25% efficiency gains, 10%~20% energy savings, and 15%~70% CO₂ reductions, validating the dual advantages of process carbon control and product quality enhancement in long-process steelmaking.

2.3. End-of-Pipe Carbon Mitigation

Current research on end-of-pipe carbon mitigation technologies for long-process steelmaking focuses on four key directions:

• Oxygen-enriched and CO₂ pre-concentration technologies: Including sinter carbon pre-concentration, lime kiln carbon pre-concentration, BF oxygen enrichment, and BF CO₂ enrichment.
• Low-cost carbon capture driven by waste heat: Analyzing steel process energy consumption, coupling medium-low temperature flue gas waste heat with carbon capture.
• CO₂ conversion to reducing gases: Catalytic hydrogenation of CO₂ (using coke oven gas-derived blue hydrogen) and CO₂ electrolysis for syngas production.
• Recycling of conversion products: Steel slag carbonation and direct utilization of CO₂ in iron/steelmaking.

By integrating CO₂ capture-conversion-utilization systems, breakthroughs aim to leverage medium-low temperature waste heat for carbon capture, directly utilize CO₂ in metallurgical processes, and develop steel-specific carbon cycle pathways. This section focuses on analyzing CO₂ recycling steelmaking technologies and carbon capture case studies.

2.3.1. CO₂ Recycling in Steelmaking Technologies

A team led by Professor Zhu Rong at the University of Science and Technology Beijing developed CO₂-utilizing steelmaking technology, integrating CO₂ into BOF operations to address challenges such as dephosphorization, denitrification, oxygen control, and bottom-blowing longevity. At Shougang Jingtang’s 300t BOF, CO₂ is utilized for process optimization (Table 6 summarizes the key technologies). By enhancing dephosphorization/ decarburization efficiency, suppressing metal evaporation, and adsorbing inclusions, this technology establishes a carbon cycle. Life cycle assessment (LCA) shows:

• 4.09 kg/t reduction in iron consumption,
• 3.73% increase in CO concentration in off-gas,
• 5.57 Nm³/t increase in gas recovery,
• 10.08 kg/t steel CO₂ utilization,
• 6.12 kgce/t reduction in energy consumption,
• 26.28 kg/t steel CO₂ emission reduction.

As illustrated in Figure 4, CO₂ recycling involves capturing, compressing, storing, and converting industrial off-gas (e.g., from steel mills and power plants) into high-value products like ethanol and oxalic acid, while enabling efficient industrial applications in metallurgy.

2.3.2. Case Analysis of Carbon Capture: Pressure Swing Adsorption (PSA) and Chemical Absorption

Pressure Swing Adsorption (PSA) separates CO₂ from gas mixtures (e.g., N₂, O₂) by leveraging differences in adsorption affinity and capacity on adsorbent media. CO₂ is adsorbed under high pressure and released during low-pressure desorption, achieving adsorbent regeneration and CO₂ enrichment. The technology has an operating cost of 300~500 CNY/t CO₂ and energy consumption of 2.5~2.8 GJ/t CO₂ (electricity). Its advantages include compact system size, low capital investment, and high-purity CO₂ output suitable for food-grade applications. However, it relies solely on electricity (unable to utilize in-plant steam), has limited CO₂ capture capacity, and requires improvements in adsorbent long-term stability.

Chemical absorption technology uses physical or chemical absorbents to capture CO₂ from gas mixtures. The absorbed CO₂ is released through heating, yielding high-concentration CO₂ gas via absorption-desorption cycles. This method incurs an operating cost of 300~400 CNY/t CO₂ and energy consumption of 3.4~3.9 GJ/t CO₂ (electricity + steam). While it offers large-scale capture capacity and matures operational stability, it faces challenges including high desorption energy consumption, severe equipment corrosion, significant solvent degradation and volatility losses, and substantial capital investment.

$$\mathrm{Reaction}\mathrm{Formula}\text{:}2R{R}^{\prime }NH+C{O}_2\iff R{R}^{\prime }NCO{O}^{-}+R{R}^{\prime }{{NH}^{+}}_2$$

The operating cost of chemical absorption ranges from 300~400 CNY per tonne of CO₂, with an energy consumption of 3.4~3.9 GJ per tonne of CO₂ (electricity and steam). While this technology offers large-scale capture capacity and mature, stable operation, it is constrained by high desorption energy consumption, severe equipment corrosion, significant solvent degradation and volatility losses, and high capital investment.

As shown in Figure 5, carbon capture, utilization, and storage (CCUS) technologies in the steel industry have transitioned from laboratory research to industrial-scale application, accelerating progress toward large-scale decarbonization. Carbon capture technologies have emerged as a core solution for end-of-pipe carbon mitigation in long-process steelmaking, with pressure swing adsorption (PSA) and chemical absorption achieving scaled implementation in low-concentration flue gas treatment and high-concentration carbon source capture, respectively, leveraging their distinct technical advantages. For instance, Shougang Jingtang’s PSA system integrated with waste heat recovery combines physical adsorption and energy cascade utilization to achieve an annual CO₂ reduction of 50,000 tonnes while reducing capture energy consumption by 20%. The project also innovates a synergistic decarbonization pathway by substituting argon with CO₂ in BOF injection. Conversely, chemical absorption demonstrates economic viability in high-concentration scenarios, such as Norway’s Elkem ferrosilicon plant with CO₂ concentrations exceeding 90%, forming a closed-loop solution through integration with geological storage. Current applications of these technologies span capture capacities of 150,000 to 1.5 million tonnes per year, with breakthroughs in energy efficiency (e.g., Dongfang Boiler’s 66% reduction in capture costs), high-value byproduct utilization (e.g., TISCO’s dry ice production generating 30 million CNY in annual revenue), and cross-sector integration (e.g., the UAE’s DRI-enhanced oil recovery project delivering $300 million in economic value). Table 7 systematically compares representative cases to reveal the intrinsic logic of technology selection and industrial scenario adaptation.

Carbon capture technologies have developed distinct pathways in steel and energy applications: Pressure Swing Adsorption (PSA) is suited for low-concentration CO₂ sources (15%~20%), exemplified by Shougang Jingtang’s project achieving annual capture of 50,000 tonnes CO₂ at a carbon cost of 240 CNY/t with 20% lower energy consumption through waste heat recovery. Chemical absorption excels in high-concentration scenarios (>90%), as seen in Norway’s Elkem project capturing 1.5 million tonnes/year, reducing carbon intensity by 60% with a storage cost of 50 EUR/t [62]. Chinese cases demonstrate cost advantages, such as TISCO’s project operating at 40 USD/t CO₂ while generating 30 million CNY/year from dry ice production. Cross-sector synergy (e.g., the U.S. Petra Nova project’s 30 USD/t revenue via enhanced oil recovery) and policy incentives (e.g., Norway’s 16 million NOK grant) are critical for scaling. Future advancements must address high energy consumption in low-concentration processing, strengthen full-process integration, and transition technologies from pilot demonstrations to systemic decarbonization.

Future technology iterations will focus on three major directions:

• Material Innovation: Develop high-capacity, sulfur- and moisture-resistant adsorbents (e.g., metal-organic frameworks, MOFs) and low-regeneration-energy solvents (e.g., phase-change absorbents like NCCC), targeting chemical absorption energy consumption below 1.5 GJ/t.
• Process Hybridization: Integrate PSA with membrane separation and cryogenic distillation for multi-stage CO₂ enrichment. For example, combining PSA (pre-concentrating CO₂ to 40%~50%) with chemical absorption (purifying to 99%) could reduce energy use by 15%~25% in blast furnace gas treatment.
• Carbon Valorization: Breakthroughs in catalytic conversion of CO₂ to methanol, polycarbonates, and other bulk chemicals, achieving >80% conversion efficiency via electrocatalysis/photocatalysis to establish a “capture-conversion-utilization” value chain.

3. Decarbonization Pathways for EAF Short Process

The carbon reduction logic of electric arc furnace (EAF) short-process steelmaking lies in transforming the material and energy flow from a linear “ore → coke → hot metal” chain to a circular “scrap → green power → recycled steel” system. This shift not only reduces process emissions but also lowers embodied carbon through resource circularity. However, global EAF steel production accounts for less than 30% [65], indicating its untapped potential as a decarbonization pillar. Realizing this potential requires balancing scrap supply-chain development with systemic enablers: scaling scrap availability and quality, establishing green power infrastructure, optimizing carbon markets, and implementing EAF-friendly policies.

3.1. Source-Stage Decarbonization

Source-stage decarbonization aims to control carbon emissions at their origin by replacing fossil fuels, optimizing energy structures, and innovating processes, thereby fundamentally reducing greenhouse gas emissions and energy consumption. Short-process steelmaking (centered on electric arc furnaces, EAFs) and hydrogen-based metallurgy have become core pathways for the steel industry’s low-carbon transition due to their inherent potential for emission reduction at the source. As analyzed in Table 8, critical components of current low-carbon EAF steelmaking include scrap pretreatment, high-efficiency waste heat recovery, intelligent process control, and green hydrogen applications with integrated energy storage systems. While these technologies exhibit significant decarbonization potential, they remain in the engineering breakthrough phase and have yet to achieve large-scale industrial adoption. Challenges persist in stabilizing energy efficiency metrics, improving equipment reliability, and overcoming high investment and operational costs.This section focuses on commercially deployed technologies, including advanced high-efficiency EAFs, green power- metallurgy coupling, and hydrogen-based shaft furnace applications. Short-process steelmaking restructures production through dual mechanisms: “scrap replacing iron ore” and “green power replacing fossil fuels”, drastically reducing embodied emissions from upstream high-carbon processes like mining and coking. This lowers carbon intensity to 0.3~0.7 tonnes CO₂/tonne of steel (20%~30% of long-process emissions) [66]. Concurrently, hydrogen-based shaft furnace technology, which directly reduces iron ore using green hydrogen, further compresses carbon intensity to 0.04~0.4 tonnes CO₂/tonne of steel [67], offering an ultimate near-zero emission solution for the industry.

3.1.1. Case Analysis of Green High-Efficiency Electric Arc Furnace Applications

The decarbonization efficacy of short-process steelmaking has transitioned from theoretical exploration to industrial validation, with globally diverse technological integrations and regionally adapted practices emerging. Table 9 systematically analyzes representative cases to elucidate innovative pathways in raw material substitution, green power integration, and process optimization for EAF steelmaking, providing scalable solutions for “source-stage carbon control” in the steel industry.

The cases in Table 9 demonstrate that achieving “source-stage carbon control” in short-process EAF steelmaking requires scrap recycling as the foundation, green power supply as the backbone, and process intelligence as the safeguard. Despite regional differences in technical pathways—such as Europe and the U.S. leveraging green power advantages, while China and Japan focus on process integration—universal strategies of increasing scrap ratios above 80%, coupling green power with waste energy recovery, and intelligent control can achieve 15%~20% CO₂ reduction per tonne of steel, validating the pivotal role of EAF short processes in the industry’s low-carbon transition.

As the core pathway for low-carbon steelmaking, EAF technology builds a multidimensional decarbonization system through raw material substitution, energy transition, and process innovation. Against the backdrop of accelerating global low-carbon steel technology evolution, the techno-economic and regional adaptability variations among leading enterprises provide critical empirical insights for industry transformation. Table 10 systematically compares four benchmark projects—ArcelorMittal Belgium (scrap recycling), Nucor USA (green power integration), Baosteel China (intensive upgrading), and Nippon Steel Japan (waste gas reuse)—to reveal how regional resource endowments and industrial policies shape low-carbon technology choices. This analysis offers actionable insights for future technology diffusion, emphasizing the need to synergize scrap recycling systems, green power infrastructure, and policy mechanisms to build an EAF steelmaking ecosystem that balances economic viability and emission reduction efficacy.

The decarbonization practices of electric arc furnace (EAF) short-process steelmaking have shifted from single technological breakthroughs to systemic innovation, relying on a four-dimensional synergy of resources, energy, technology, and policy. Future efforts require material upgrades (promoting hydrogen-based DRI coupling and establishing a complete lifecycle traceability system for scrap), energy innovation (integrated wind-solar-storage power supply targeting ≥80% green electricity penetration and green hydrogen substitution), and intelligent integration (AI optimization of the entire smelting process, such as digital twins, and democratization of modular technologies), ultimately achieving carbon neutrality in the steel industry.

3.1.2. Case Analysis of Advanced Electric Arc Furnace (EAF) Applications

The electric arc furnace (EAF) redefines the energy and material metabolism of steel production through its dual substitution logic—”electricity replacing carbon-based fuels” and “scrap replacing iron ore”—making it a core enabler of low-carbon short-process steelmaking. As global carbon neutrality goals intensify and regional demands for scrap resources, power structures, and production scales diversify, EAF technology has evolved into a multi-branch collaborative system. Calculations indicate that the carbon intensity of scrap-based EAF routes (0.3~0.7 t CO₂/t steel) is only 20%~30% of long-process routes, significantly reducing embodied emissions from upstream mining, sintering, and coking.

With rising demand for deep decarbonization, short-process steelmaking innovations centered on EAFs are diversifying globally. As shown in Table 11, advanced EAF deployments are expanding regionally: China focuses on EAF upgrades led by MCC-CISDI and hydrogen metallurgy pilots by Baowu; Europe emphasizes hydrogen reduction and large-scale EAFs in Germany (SMS Group, ThyssenKrupp) and Voestalpine’s Hyfor technology; while Japan’s SPCO Eco-Arc EAF and the U.S.’s Danieli Q-ONE power system exemplify advancements in the Asia-Pacific and North America. These regional strategies integrate localized resources and policies, driving the steel industry toward carbon neutrality through tailored technological pathways.

As systematically categorized in Table 12, the differentiated technological characteristics and industrial implementation outcomes of mainstream international low-carbon electric arc furnaces (EAFs) are comprehensively analyzed. By conducting comparative analyses of critical metrics,including innovations in power supply modes, advancements in intelligent control systems, and compatibility with hydrogen-based feedstocks,this study elucidates the synergistic emission-reduction effects across distinct technological pathways. It defines the boundary conditions for their scaled deployment.

Analysis of Current Intelligent EAF Technologies as described in Table 12.Current intelligent electric arc furnace (EAF) technologies achieve 300~350 kWh/t steel energy consumption, 20%~80% CO₂ intensity reduction, and 30-minute smelting cycles (e.g., Panzhihua Special Steel Project saving ¥20 million annually) through innovations such as waste heat power generation from scrap, AI dynamic models (endpoint carbon control accuracy of ±0.02% [85]), and hydrogen-based DRI synergy (80% emission reduction). However, challenges persist in low-density scrap melting efficiency, high green hydrogen costs, and limited multi-objective coordination accuracy.

Future advancements require accelerated development of:

• Hydrogen-Electric Coupling Processes: Integrating technologies like Danieli Q-ONE with green hydrogen to enhance decarbonization.
• Blockchain-Based Carbon Tracking Systems: Ensuring transparency in emission reduction across supply chains.
• Carbon Tax Policy Incentives: Driving adoption through fiscal mechanisms (e.g., >$80/t CO₂ pricing).

By 2030, these efforts aim to halve EAF steel carbon emissions compared to 2020 levels, providing critical support for global steel industry carbon neutrality.

3.1.3. Case Studies of Low-Carbon Green Power Applications

The application of green renewable electricity represents a critical pathway for decarbonizing electric arc furnace (EAF) steelmaking. Globally, multiple exemplary cases demonstrate the potential of integrating green power with EAF technology. Through various renewable energy technologies—including solar, wind, hydropower, and green hydrogen electrolysis—these projects achieve significant carbon emission reductions in steel production. Detailed case studies and their specifications are presented in Table 13.

The cases in Table 13 highlight both the substantial potential and positive outcomes of adopting green renewable electricity in the global steel industry. They also reveal regional variations in resources, technologies, and policy frameworks. Further expansion of green energy technologies will accelerate the steel sector’s sustainable development, driving continued low-carbon transformation and technological innovation worldwide.

3.1.4. Case Analysis of Hydrogen-Based Shaft Furnace Applications

Hydrogen-based shaft furnace technology has emerged as a core solution for low-carbon transformation in the steel industry. By replacing traditional coke-based blast furnaces with green hydrogen/hybrid gas reduction of iron ore, this approach reduces carbon intensity to 0.04~0.4 tonnes CO₂/tonne of steel (60%~98% lower than conventional blast furnaces). Global flagship projects such as MIDREX H₂ (with metallization rates exceeding 94%) and HYBRIT demonstrate breakthroughs in green hydrogen-driven reduction, waste heat integration, and short-process optimization. However, challenges including high green hydrogen costs (USD 4~6/kg), DRI reoxidation risks, and hydrogen storage/transportation bottlenecks hinder large-scale adoption.The following comparative analysis of typical projects (Table 14) reveals the differences in their technical pathways, economic viability, and applicable scenarios.

As shown in Table 14, hydrogen-based shaft furnaces reduce carbon intensity by 60%~98% through three strategies: deep green hydrogen substitution (HYBRIT achieves 25 kg CO₂/tonne steel), hybrid gas transition (Baowu Zhanjiang uses 13% green hydrogen), and integrated process innovation (SALCOS produces hydrogen from waste heat at 3.5 kWh/Nm³). These innovations also lower energy consumption per tonne of iron by 40% (China Iron & Steel Research Institute) and extend equipment lifespan to 30,000 hours (Baowu Zhanjiang). Despite this progress, critical barriers remain, such as natural gas dependency in MIDREX H₂, DRI stability issues requiring carburization processes, and liquid hydrogen costs accounting for 35% of SALCOS operations.

Currently transitioning from pilot projects to diversified pathways, hydrogen-based shaft furnaces prioritize 100% green hydrogen routes as the ultimate goal. Short-term solutions involve hybrid/gray hydrogen systems, supported by material innovations (hydrogen-resistant alloys, high-strength pellets), energy recycling (waste heat utilization), and policy incentives (carbon pricing, hydrogen subsidies). With declining renewable energy costs and maturing green hydrogen supply chains, this technology is projected to achieve large-scale adoption by 2035, potentially halving global steel industry emissions. Regional strategies vary: Europe focuses on pure hydrogen routes, China optimizes hybrid systems, and North America addresses infrastructure gaps through modular solutions. Success hinges on overcoming economic and technical barriers through cross-sector collaboration.

3.2. Process Carbon Control

Under the global consensus of “dual carbon” goals, the steel industry, as a major carbon emitter, urgently requires technological innovation to achieve green transformation. Short-process electric arc furnace (EAF) steelmaking, which primarily uses scrap steel as raw material and eliminates high-carbon-emission coking and blast furnace processes, has emerged as a key pathway for low-carbon steel production. However, traditional EAF steelmaking still faces challenges such as significant carbon content fluctuations, high energy consumption, and interference from scrap impurities.

As shown in Table 15, current pilot technologies for carbon control in short-process EAF steelmaking include fully automated scrap intelligent batching systems, scrap classification, and impurity control, among others, which are actively under research and development. This section focuses on the more mature intelligent system control technologies, which dynamically optimize process parameters to achieve precise carbon control and energy efficiency improvements.

Through intelligent system control technologies ( such as dynamic endpoint regulation, scrap preheating optimization, and arc stability enhancement ) global steel enterprises have significantly reduced energy consumption and carbon emission intensity in electric arc furnace (EAF) steel production. Case studies in Table 16 demonstrate the practical application effects of intelligent control technologies in EAF steelmaking, covering process parameters, carbon control metrics, and economic benefits.”

Table 16 demonstrates significant global advancements in intelligent EAF steelmaking technologies: Nucor’s (USA) twin-shaft scrap preheating system (45% efficiency), HBIS Shisteel’s (China) dynamic endpoint control (±0.02% carbon deviation [116]), and SMS Group’s (Germany) arc stability optimization (50% harmonic reduction [114]) have collectively reduced power consumption to 250~270 kWh/t steel and decreased CO₂ intensity by 18%~35%, achieving annual emission reductions of 300,000~500,000 tons. Danieli’s (Italy) AI stockyard system improved scrap utilization to 98% (annual savings: $12 million [115]). Current challenges include scrap impurity interference, high green hydrogen costs, and insufficient multi-objective control precision. Future development requires accelerated hydrogen-based DRI-EAF integration (e.g., Danieli Q-ONE) and digital twin real-time control systems to advance steel industry carbon neutrality.

3.3. End-of-Pipe Treatment

Current end-of-pipe treatment technologies for EAF short-process steelmaking, such as plasma-assisted emission reduction and ultra-low-energy membrane separation (as listed in Table 17), have achieved partial breakthroughs in pilot-scale projects. However, their industrial application maturity remains constrained by high energy consumption and insufficient process stability, requiring further optimization and validation. In contrast, waste heat recovery and slag treatment technologies have established mature industrialized application models, serving as the core pathways for emission reduction and efficiency enhancement in current EAF short-process production.

3.3.1. Case Studies on Waste Heat Utilization in EAF Steelmaking

Driven by global dual-carbon goals, the steel industry, as a major carbon emitter, urgently requires technological innovation to achieve a low-carbon transition. EAF steelmaking has emerged as a core pathway for decarbonization due to its reliance on scrap steel as the primary feedstock, shortened process flows, and significantly lower carbon emission intensity (only 20%~30% of the blast furnace~basic oxygen furnace route). However, substantial waste heat resources in EAF processes remain underutilized, including high-temperature flue gas (1,300~1,500°C), cooling water (50~85°C), and slag sensible heat, with energy losses accounting for 15%~25% of total input energy. Recent advancements in waste heat recovery technologies have enabled global steelmakers to markedly improve energy efficiency and reduce carbon emissions. Table 18 presents representative case studies of EAF waste heat utilization projects across leading enterprises, covering applications such as flue gas power generation, scrap preheating, and waste heat district heating.

Waste heat utilization technologies in EAF steelmaking have evolved from singular thermal energy recovery to integrated solutions encompassing flue gas power generation, scrap preheating, and molten bath stirring optimization. Global practices demonstrate that technologies such as evaporative cooling (e.g., Tianjin Pipe Group’s annual power generation of 46,000 kWh in China), post-combustion (e.g., 60% CO post-combustion rate in Germany’s CONSTEEL project), and DC EAF-coupled waste heat boilers (e.g., Nippon Steel’s annual power generation of 8.4 GWh in Japan) can reduce power consumption by 5%~30% per tonne of steel and lower CO₂ emissions by 16,000~37,000 tonnes annually, delivering significant economic and environmental benefits.However, challenges persist, including high technical complexity, substantial capital costs, and difficulties in regulating intermittent flue gas fluctuations. Future advancements require intelligent waste heat management systems, cascaded utilization of high-temperature flue gas chemical energy (e.g., hydrogen coupling), and cross-process multi-energy complementary models (e.g., synergies between waste heat district heating and power generation). Concurrently, international standards and policy incentives must be strengthened to accelerate technology adoption. The decarbonization of EAF steelmaking relies not only on process innovations but also on full-chain efficient utilization of waste heat resources to establish zero-waste energy recycling systems, serving as a core enabler for achieving carbon neutrality in the global steel industry.

3.3.2. Case Studies on Slag Treatment in EAF Steelmaking

The efficient utilization of electric arc furnace (EAF) steelmaking slag plays a crucial role in achieving low-carbon steel production and promoting a circular economy. Globally, steel enterprises and research institutions have developed various slag valorization approaches through technological innovation, covering metal recovery, building material substitution, thermal energy utilization, and environmental remediation. Table 19 presents representative global application cases of EAF slag treatment, demonstrating the energy-saving, emission-reduction effects, and economic benefits of different technical approaches, with data derived from multinational empirical studies and industrial practices.

The global application cases of EAF slag treatment presented in Table 19 demonstrate that integrated technologies have successfully achieved value-added utilization of steel slag worldwide. These practices confirm that slag valorization can simultaneously deliver carbon emission reductions (15%~30% annually), decrease reliance on natural resources (with 1.2 Mt/year iron ore substitution [135]), and enhance industrial value (achieving 8%~40% comprehensive cost reductions), thereby establishing replicable technical models and commercial pathways for end-of-pipe treatment in global short-process steelmaking.

Current EAF slag treatment technologies have developed a comprehensive valorization system focused on metal recovery, construction material substitution, and thermal energy utilization. Nevertheless, the field continues to face challenges including significant chemical composition variability and limited options for high-value applications. Future technological advancements should concentrate on developing efficient mineral separation techniques such as flotation and combined magnetic-gravity separation processes to enhance the precision of separating metallic and silicate phases. This should be complemented by establishing life cycle assessment models for slag through multi-scale simulation to optimize slag system design and application compatibility. Further research should explore the synthesis mechanisms of slag-based functional materials including CO₂ sequestration carriers and catalytic materials to expand their applications in renewable energy and environmental remediation sectors. Additionally, promoting intelligent control technologies and fostering cross-industry collaboration among metallurgical, construction, and chemical industries will be crucial to achieving slag composition standardization and facilitating large-scale utilization.

Through continued technological innovation and supportive policy frameworks, EAF slag has the potential to transition from being merely an end-of-pipe treatment target to becoming a valuable low-carbon resource carrier, thereby contributing systemic solutions toward the global steel industry’s carbon neutrality objectives. Currently, key low-carbon technology development for EAF processes remains focused on charge structure optimization, specialized power supply system development, material and energy consumption modeling, AI-based efficient power supply technologies, full-scrap EAF rapid melting process simulation, bottom stirring optimization design, dynamic operation optimization, and intelligent control systems implementation. While the adoption of short-process EAF steelmaking has emerged as a consensus approach for achieving deep decarbonization in the steel industry, this seemingly straightforward pathway still contains numerous hidden barriers that require systematic resolution through coordinated technological breakthroughs and policy support.

4. Summary and Outlook

Global carbon neutrality goals are driving the emergence of low-carbon steelmaking technologies as the core pathway for the steel industry’s green transformation. Current developments exhibit three key characteristics: parallel advancement of multiple technological routes, regionally adaptive optimization, and cross-industry supply chain collaboration. While traditional blast furnace-basic oxygen furnace (BF-BOF) long-process routes are achieving incremental decarbonization through process innovations and end-of-pipe carbon capture technologies, electric arc furnace (EAF) short-process routes demonstrate disruptive emission reduction potential via scrap recycling and green energy integration. Hydrogen-based metallurgy, which utilizes green hydrogen as a carbon-free reductant, represents the ultimate deep decarbonization solution. However, technological evolution faces persistent challenges including high green hydrogen costs, inconsistent scrap quality, inadequate intelligent control precision, and mismatched regional resource-energy infrastructure, necessitating coordinated solutions through policy incentives, carbon pricing mechanisms, and international cooperation.

Looking ahead, declining renewable energy costs, maturing hydrogen supply chains, and digitalization integration will accelerate the industry’s transition toward renewable energy-driven systems, hydrogen-based alternatives, and closed-loop circular systems. For long-process routes, multi-technology integration—such as optimizing gas injection media combinations, enhancing carbon capture efficiency, and improving resource recovery rates—will maximize decarbonization potential. Short-process routes require advancements in scrap pretreatment technologies, renewable energy-storage synergy systems, and deep integration of hydrogen-based direct reduced iron (DRI) with EAFs to establish “resource recycling–clean energy–high-efficiency production” closed-loop ecosystems. Critical focus areas include high-quality scrap utilization, low-carbon smelting process innovation, equipment intelligence/scaling, and energy system optimization.

Policy frameworks must strengthen top-level design through standardized scrap recycling protocols, robust carbon pricing mechanisms, and green finance support for R&D. Industry players should pioneer cross-sector collaboration models encompassing slag valorization and hydrogen metallurgy-chemical co-production. The metallurgical sector must intensify fundamental research, promote interdisciplinary technology convergence, and establish globally recognized green certification standards under carbon market frameworks. This comprehensive transformation—from “carbon metallurgy” to “green metallurgy”—will position the steel industry as a cornerstone of global industrial decarbonization, providing critical technical and systemic support for achieving climate objectives.