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Article

Analysis of Technological Pathways and Development Suggestions for Blast Furnace Low-Carbon Ironmaking

by
Haifeng Li
1,2,*,
Yan Zhao
2,
Chengqian Guo
2 and
Junqi Li
2
1
Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education), Northeastern University, Shenyang 110819, China
2
School of Metallurgy, Northeastern University, Shenyang 110819, China
*
Author to whom correspondence should be addressed.
Metals 2024, 14(11), 1276; https://doi.org/10.3390/met14111276
Submission received: 15 October 2024 / Revised: 5 November 2024 / Accepted: 8 November 2024 / Published: 9 November 2024
(This article belongs to the Special Issue Advanced Simulation and Modeling Technologies of Metallurgical Processes)
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Abstract

:
Under the global dual-carbon background, heightened public awareness of climate change and strengthened carbon taxation policies are increasing pressure on the steel industry to transition. Given the urgent need for carbon reduction, the exploration of low-carbon pathways in a blast furnace (BF) metallurgy emerges as crucial. Evaluating both asset retention and technological maturity, the development of low-carbon technologies for BFs represents the most direct and effective technical approach. This article introduces global advancements in low-carbon metallurgical technologies for BFs, showcasing international progress encompassing hydrogen enrichment, oxygen enrichment, carbon cycling technologies, biomass utilization, and carbon capture, utilization, and storage (CCUS) technologies. Hydrogen enrichment is identified as the primary technological upgrade currently, although its carbon emission reduction potential is limited to 10% to 30%, insufficient to fundamentally address high carbon emissions from BFs. Therefore, this article innovatively proposes a comprehensive low-carbon metallurgical process concept with the substitution of carbon-neutral biomass fuels at the source stage—intensification of hydrogen enrichment in the process stage—fixation of CCUS at the end stage (SS-IP-FE). This process integrates the cleanliness of biomass, the high-efficiency of hydrogen enrichment, and the thoroughness of carbon fixation through CCUS, synergistically enhancing overall effectiveness. This integrated strategy holds promise for achieving a 50% reduction in carbon emissions from BFs in the long processes. Critical elements of these core technologies are analyzed, assessing their cost-effectiveness and emission reduction potential, underscoring comprehensive low-carbon metallurgy as a pivotal direction for future steel industry development with high technological feasibility and emission reduction efficacy. The article also proposes a series of targeted recommendations, suggesting short-term focus on technological optimization, the medium-term enhancement of technology research and application, and the long-term establishment of a comprehensive low-carbon metallurgical system.

1. Introduction

The steel industry is one of the main industries in terms of energy consumption and carbon emissions, making it crucial to address its environmental impact. With the growing awareness of climate change and the need for environmental protection, coupled with the implementation of stricter carbon tax policies, the pressure to reduce carbon emissions in the steel industry has significantly intensified [1]. China aims to peak carbon dioxide (CO2) emissions before 2030 and achieve carbon neutrality by 2060 [2], officially marking China’s entry into the “dual carbon” era.
In the context of “dual carbon”, the green and low-carbon development of the steel industry has become the core issue in the current transformation and development of the industry. Currently, China mainly produces steel through the long process of the blast furnace–basic oxygen furnace (BF-BOF). Considering factors such as asset preservation and technological maturity, the BF is expected to remain the mainstream ironmaking technology in China for the next several decades. In 2023, the global BF pig iron production was 1.2865 billion tons, a year-on-year growth of 0.5%. As the world’s largest producer of crude steel, China’s BF pig iron production reached 871 million tons, an increase of 0.7% year on year, with crude steel production reaching 1.019 billion tons, accounting for approximately 54.0% of global crude steel production, remaining relatively stable compared to the previous year. Compared to other industries in China, the steel industry still ranks first in CO2 emissions among non-power industries. For the carbon-intensive Chinese steel industry, which is primarily based on the BF-BOF long processes, it is facing unprecedented challenges in emission reductions. Therefore, the development of innovative low-carbon technologies predominantly focused on the BF-BOF long process assumes paramount importance.
In order to reduce reliance on carbon-based fossil fuels, the BF ironmaking sector is increasingly turning its attention to alternative energy sources such as hydrogen and biochar. Hydrogen energy is widely regarded as one of the most promising clean energy sources of the 21st century, possessing advantages such as cleanliness, efficiency, and high calorific value. Utilizing hydrogen gas (H2) as an alternative fuel or a reducing agent can not only address the issue of depleting fossil fuel reserves but also help mitigate the global greenhouse effect, making hydrogen energy smelting one of the key pathways for achieving zero emissions in the steel industry. Biomass is a form of energy carrier that stores solar energy in chemical form, fixing atmospheric CO2 through photosynthesis and exhibiting zero carbon emissions [3]. Biochar, generated from biomass through thermochemical processes, is a solid fuel with carbon content and calorific value comparable to some special coal types (such as bituminous coal) [4], holding the potential to replace part of coal powder injection in BFs.

2. Global Development Status of BF Low-Carbon Metallurgical Technology

BF low-carbon smelting is a process that involves injecting hydrogen-rich fuels [5] (such as natural gas (NG), coke oven gas (COG), etc.) into the BF to partially replace coke, thereby playing a role in reducing coke consumption, saving coke costs, and lowering carbon emissions. As for the specific types of fuels chosen for injection into BFs in various countries around the world, this depends on the economic viability of obtaining specific fuel types in each country. For example, in regions such as North America and Russia, where NG resources are abundant, the BF injection of NG technology is more prevalent [6]. Conversely, in resource-rich yet gas-deficient regions like China, COG injection predominates, acting as a supplementary reducing agent in the ironmaking process.
The carbon emissions during BF smelting primarily hinge on the utilization of fossil fuels (coke, coal powder, etc.). Presently, the average fuel consumption of a BF is around 545 kg/t, which is approximately 40 kg/t higher than the international advanced level. The coke ratio is around 330–370 kg/t [7]. In order to reduce reliance on fossil fuels, the steel industry has conducted long-term research, with the most representative processes including hydrogen-rich blast furnaces (H-BFs), carbon cycle oxygen blast furnaces (CC-OBFs), hydrogen-based direct reduction (H-DR), and smelting reduction (SR)-BOF [8]. This study focuses primarily on BF technologies, notably hydrogen-rich BF and carbon cycle oxygen BF processes. Since the 21st century, countries including Japan, Germany, the European Union, and China have embarked on strategic initiatives for low-carbon metallurgy, exemplified by Japan’s COURSE50 project [9,10,11,12], Germany’s Low-Carbon Ironmaking project [13,14], the EU’s Ultra-Low CO2 Steelmaking (ULCOS) initiative [15], and China’s hydrogen-rich (carbon cycle) BF technologies.

2.1. International Progress of BF Low-Carbon Metallurgical Technology

At present, major steel-producing nations around the world have not forsaken the traditional BF-BOF long process. They are earnestly undertaking efforts to combat climate change and diminish carbon emissions, thereby initiating numerous low-carbon BF research projects. Table 1 presents an overview of representative international low-carbon BF projects. The primary objective of these undertakings is to reduce carbon emissions in the steel production process through technological innovation, energy substitution, and carbon capture, thus propelling the steel industry towards a more sustainable trajectory.

2.2. Domestic Progress of BF Low-Carbon Metallurgical Technology

As of December 2023, China’s steel production remains predominantly reliant on the BF-BOF long process method. Furthermore, the average service life of existing BFs in China is approximately 12 years, significantly below the industry’s average lifespan of 40 years [17]. Motivated by the “dual-carbon” objective, low-carbon smelting in BFs emerges as the principal avenue for the steel industry to realize carbon reduction and emission mitigation. The technical features of low-carbon smelting in BFs are “hydrogen-rich, oxygen-rich, and carbon cycle”, as shown in Figure 1 [18,19].
By injecting hydrogen-rich fuels into the BF tuyere effectively increases the content of reducing gases inside the furnace, thereby enhancing production efficiency and reducing solid fuel consumption. The use of oxygen-enriched blast technology effectively prevents large quantities of nitrogen (N2) from entering the BF, facilitating the effective separation of CO and CO2 in the top gas and redirecting the high-concentration CO-formed reducing gas back to the furnace hearth or tuyere, thereby recycling the chemical energy of carbon. Simultaneously, through gas circulation, the recycling of H2 within the BF resolves the issue of decreased hydrogen utilization efficiency following the injection of hydrogen-rich fuels, providing technical support for the widespread application of hydrogen-rich fuels in BFs.
Recent years have witnessed substantial progress in low-carbon technologies for BFs [18,19,20,21,22,23,24,25], marked by significant advancements from leading steel enterprises and research institutions. Table 2 provides a comprehensive summary of the technological pathways and key accomplishments of recent low-carbon BF projects in China, showcasing the country’s pioneering exploration and progress in the realm of BF decarbonization.
The implementation of aforementioned low-carbon BF projects encompasses various aspects, including the retrofitting of traditional BFs to achieve carbon cycling, the injection of hydrogen-rich and biomass fuels to replace carbon, and the incorporation of CCUS technologies for carbon fixation. These measures are aimed at realizing carbon emission reduction targets within the steel industry and contributing to the global steel sector’s transition towards more environmentally friendly and sustainable practices. Furthermore, these projects align with international calls for sustainable development and make positive contributions to achieving carbon neutrality and mitigating climate change.

3. Analysis of the Comprehensive BF Low-Carbon Smelting Technological Pathways

In the exploration of low-carbon smelting technologies for BFs, a comprehensive low-carbon smelting process has been proposed, incorporating the advantages of existing pathways as depicted in Figure 2. This process is termed “Substitution of carbon-neutral biomass fuels at the Source stage—Intensification of hydrogen-enrichment in the Process stage—Fixation of CCUS at the End stage”, referred to as SS-IP-FE. At the source stage, the emphasis is placed on the research and application of biomass preparation technologies. In the process stage, the focuses are the technical application of hydrogen-rich fuel injection in the exploration of low-carbon smelting technologies for BFs to reduce CO2 emissions by hydrogen-rich enhancement. If possible, injecting green hydrogen into the furnace from the shaft tuyere may be a better choice. At the end stage, the key technology is CCUS to achieve carbon component separation and recycling. The entire process aims to efficiently utilize multi-source gas–solid composite low-carbon fuels, with the innovative process expected to provide crucial support and direction for the sustainable development of the steel industry. Considering the heterogeneity in technology and resource availability, the existing blast furnace infrastructures needs to be improved, such as adding decarbonization equipment, adding biomass treatment processes, redesigning injection devices, and so on.

3.1. Pathway of Carbon Substitution with Biomass at the Source Stage

Biofuels are being promoted as a low-carbon alternative to fossil fuels, as they could help to reduce greenhouse gas (GHG) emissions and the related climate change impact from transport. Biochar is a porous, carbon-rich solid material primarily derived from the thermochemical conversion of biomass through processes such as pyrolysis and hydrothermal carbonization. With its carbon content and calorific value similar to coal, biochar has the potential to replace coal powder for injection into BFs [26], which aims to reduce the consumption of coal powder combustion by increasing the proportion of biochar blending, thus achieving carbon reduction at the source. Currently, only a few countries have industrial applications of biochar injections in BFs [27]. For instance, Brazil is the only country in the world that produces iron using biochar in small BF (<350 m3), accounting for nearly 30% of its steel production. These small BFs using biochar with top charging and tuyere injection have achieved a tuyere injection rate of 100–150 kg/t, resulting in a 30% reduction in CO2 emissions [27,28]. Furthermore, experiments related to this technology have been conducted in other countries. For example, trials conducted by SSAB in Sweden demonstrated that coal powder and wood charcoal could be co-injected without encountering any process-related issues [29]. The successful completion of the hundred-ton scale continuous injection industrial trial of biochar in BFs by China’s Shougang Group also confirmed the feasibility of this technology [25].
Research on the preparation of BF injection fuel by biomass carbonization and upgrading has demonstrated notable advancements. YUAN X et al. [30] conducted a comparative analysis of the influence of pyrolysis carbonization and hydrothermal carbonization processes on their injection performance. The findings revealed that biochar produced through hydrothermal carbonization demonstrates superior quality, with reduced levels of detrimental elements, such as alkali metals, rendering it suitable for BF injection applications. DAN J Y et al. [31] explored the feasibility of utilizing a blend of biochar and pulverized coal for BF injection. Their results suggested that as the proportion of biochar in the coal blend increases, the combustion performance of the coal blend improves. Specifically, when the biochar content ranges from 5% to 20% in the coal blend, there is a marginal decrease in the fixed carbon content and calorific value of the coal blend, while still meeting the safety requirements for BF injection. Additionally, LI T et al. [32] investigated the changes in combustion performance after the injection of a blend of coal powder and biochar. Their findings indicate that the co-injection of anthracite coal and biochar results in improved combustion performance, with more rational temperature, velocity, and gas phase distribution. Additionally, following the coal blend injection, the highest temperature in the raceway is elevated. Both the overall combustion efficiency and anthracite coal combustion efficiency increased by 6% and 2.1%, respectively. In summary, biochar, as an auxiliary fuel for BF injection, not only contributes to the reduction of carbon emissions but also facilitates the combustion of coal powder.
Due to the production of liquid, gaseous, and solid fuels during biomass pyrolysis, BABICH A et al. [33] investigated the co-injection of biogas and biochar into BFs as a method to enhance biomass utilization efficiency. Computational results indicate that depending on the composition of the biogas, the BF productivity can increase by 10% to 25% when injecting 100 m3/t of biogas. Simultaneously, the volume and temperature of the furnace top gas decrease while the hydrogen content and calorific value increase, thereby reducing heat losses. Fick et al. [34] studied the application of biomass fuels in various steel production scenarios. Compared to using exclusively fossil fuels, the use of biomass in steel production processes can reduce greenhouse gas emissions by 6.7% to 14.7%. The emission reduction effectiveness primarily depends on the type of biomass, its processing methods, and its utilization in BFs. The analysis suggests that injecting charcoal powder at the tuyere is the most cost-effective solution.

3.2. Pathway of Intensification with Hydrogen-Rich Fuel in the Process Stage

According to current research, fuels suitable for hydrogen-rich injection into a BF mainly include COG, NG, H2, and recycled top gas (RTG) [35]. Among these, COG is a hydrogen-rich fuel generated during coking, with a hydrogen volume fraction of approximately 55% to 62%, making it a high-quality fuel with high hydrogen content and high calorific value. NG primarily consists of alkanes, with methane (CH4) and other alkane gases accounting for around 97%. The RTG is a secondary recycled resource obtained after CO2 capture, which enhances the utilization of C and H. It contains a high-volume fraction of CO, reaching over 77% in some cases. Hydrogen-rich smelting changes the thermodynamic and kinetic conditions for the reduction of traditional BF burden, but there are differences in the appropriate injection volume and injection effect of different hydrogen-rich media.
Zhang W G et al. [36] found that NG has the most significant impact on direct reduction rate, tuyere coke quality, and theoretical combustion temperature, followed by COG, with BF top gas having the least impact. Additionally, injecting NG has the most pronounced emission reduction effect, with a 9.46% decrease in CO2 emissions observed when injecting 60 m3 of NG. Zhang C L et al. [37] found that under the same hydrogen-rich gas injection rate, the temperature difference of reactions between RTG and H2 with coal in the raceway region is minimal. However, when injecting NG, the average temperature within the raceway and along the central axis of the pulverized coal (PC) stream is lowest. Nevertheless, the molar fraction of reducing gases within the raceway is highest when injecting NG and lowest when injecting H2. Oxygen consumption from NG combustion has the greatest impact on coal powder combustion, resulting in the lowest burnout rate of PC, whereas the burnout rate of PC is highest when injecting RTG. WANG X D et al. [38] found that injecting NG, COG, and H2 into a BF can reduce the coke ratio by over 10%. Among these, the most significant effect was observed with the injection of coal powder mixed with natural gas. Additionally, preheating hydrogen-rich fuels can notably enhance their energy-saving and emission-reducing potential. Injecting a mix of coal powder and H2 preheated to 950 °C can achieve the highest reduction rates in carbon consumption per ton of iron and CO2 emissions, reaching up to around 30%. Injecting other preheated hydrogen-rich fuels in combination can also achieve reductions of about 10%. YILMAZ C et al. [39] determined through numerical simulation that the optimal injection rate of H2 is 27.5 kg/t. At this time, the coke ratio decreases by 24%, and CO2 emissions decrease by 21%.
In addition, CASTRO J A et al. [40] proposed a new process involving hydrogen-rich, oxygen-rich, and BF top gas mixed injection, achieving up to a 20.5% productivity increase and maximum injection of 210.3 kg/t BF gas, with a CO2 reduction of up to 14.8%. GAN M J et al. [41] proposed a decarbonization technique for BF involving the co-injection of hydrogen and biochar (CoHB) and conducted a comprehensive analysis of the interaction between hydrogen and biochar. The study indicated that the heat released from H2 combustion enhances the devolatilization process of biochar, and appropriate hydrogen injection can improve biochar burnout rates by up to 6%. The technique is considered feasible without requiring significant equipment modifications and can draw from PCI operational experience. GAN M J et al. [42] used CFD modeling to predict that the maximum overall burnout rate of biochar in CoHB technology reaches 51.71%.
These studies indicate that injecting various hydrogen-rich fuels into BF can reduce fuel consumption and CO2 emissions, albeit to a limited extent (10% to 30%), without fundamentally solving carbon emissions from BFs. The substitution of hydrogen for carbon inevitably brings an increase in energy consumption for reduction, but there are two ways to solve this problem: the first is to establish a technique for supplying heat to the reactor from outside or injecting high-temperature hydrogen, and the second is to establish an oxygen-enriched combustion technology to steadily supply a large amount of hydrogen-based gas into the reactor that considers the endothermic characteristics of hydrogen-rich fuel injection pyrolysis. The above two technologies need to optimize the process parameters in order to maximize the matching of energy balance and reduction potential. To solve the above problem, the author proposed a new process for RSF with Hy-O-CR in the previously published literature [23,43], which requires improvement of the furnace type and is divided into two-stage tuyere injections.

3.3. Pathway of Carbon Fixation at the End Stage

In the process of steel production, flue gases produced by a coking oven, BF, converter, etc., all contain varying amounts of CO2. Particularly in BFs, the high CO2 content in the top gas, the low utilization rate of carbonaceous reducing agents, and actual CO2 emissions reaching 1.61 t/t [44] necessitate the use of CCUS technology to solidify end-stage tail gases to reduce carbon emissions. Currently, CCUS technologies applied in the steel industry involve the chemical absorption (e.g., organic amines), physical adsorption (pressure/thermal swing adsorption), and membrane separation for capturing and separating CO2 generated during the production process and before the circulation utilization of top gas, ultimately enabling the captured CO2 to be recycled or directly stored, as illustrated in Figure 3. It is anticipated that around 2030, China will begin the large-scale promotion of CCUS technology in the steel industry, with the application proportion expected to reach 15% to 35% by 2050. This will achieve a reduction in CO2 emissions of around 20%.
In the long flow involving the BF-BOF, there are various methods for utilizing CO2. For example, the Japanese steel industry plans to use chemical methods to convert CO2 in BF gas into CH4, which can then be used as a reducing agent to replace a portion of the coal coke. Additionally, the University of Birmingham in the UK [45] has proposed a thermochemical-BF-converter coupled gas CO2 conversion CO backflow carbon reduction process. Furthermore, Chinese researchers proposed the idea of using CO2 as a carrier for coal injection in BF in 2011 [46]. In 2020, Taishan Steel Group successfully conducted experimental trials of BF CO2 injection technology. Moreover, CO2 can also be used in the top/bottom blowing of converters to replace N2 or Ar, aiding in impurity removal from iron and increasing the dephosphorization rate. In summary, these methods can effectively utilize CO2 in the BF smelting process, reduce the production costs of chemical products, promote steel-making co-production, and realize the coupled capture and utilization of CO2 from top gas in the furnace.

3.3.1. CO2 Injection Technology in BF

The primary technical principle of CO2 injection technology is that CO2 can be reduced to CO by carbon at high temperatures in BFs. Although this reaction needs to consume a fraction of the reducing agent (e.g., coke), it concurrently facilitates the conversion of CO2 into CO, thereby improving the indirect reduction of ore in the upper part of the BF. This process achieves the objective of recycling exhaust gases for reuse, consequently reducing carbon emissions of the BF.
SHATOKHA V et al. [47] investigated the potential of injecting CO2 into a BF. The study revealed that injecting CO2 without adding H2 increases the coke ratio, reduces productivity, and increases direct CO2 emissions, with CO2 injection rates reaching up to 61.3 kg/t. However, a simultaneous injection of H2 and CO2 maintains a stable coke ratio. As the mass ratio of H2 to CO2 increases, productivity improves, the coke ratio begins to decrease, and direct CO2 emissions are reduced. WANG H Y et al. [48] found that with increasing CO2 injection, the blast kinetic energy of OBF, coke rate, belly gas volume, and top gas calorific value all increase, while theoretical combustion temperature and direct reduction degree decrease. This indicates that moderate CO2 injection can serve as a means to adjust operational parameters of OBF. JIANG J J et al. [49] analyzed the impact of tuyere CO2 injection on the coal combustion rate. The results indicated that increasing CO2 content in hot blast does not significantly alter the overall temperature field in the furnace but improves pulverized coal burnout. CO2 reacts predominantly at the center of the coal jet, where increased CO2 exacerbates coal combustion delay. SONG H L et al. [50] studied the impact of CO2 injection in the BF on the high-temperature metallurgical performance of chromium–vanadium–titanium magnetite. They found that injecting CO2 into a BF with high-temperature, energy-carrying gases is feasible, as it ensures thermal balance in the high-temperature zone while significantly reducing the coke rate. According to their calculations, the optimal CO2 injection rate is approximately 15.3%. Experimental findings confirmed that the best CO2 injection ratio ranges from 10% to 20%, aligning closely with the calculated results.

3.3.2. CO2 Off-Furnace Reforming Recycling in BF

The application of CO2 off-furnace reforming recycling of a BF is to convert CO2 into CO and return it to the BF by adding an external reforming device with CCUS technology so as to realize the carbon cycle of BFs.
YANG Y et al. [51] systematically reviews the research and application progress of various carbon capture technologies. HU Y C et al. [52] proposed the utilization of electrochemical CO2 conversion technology for the transformation of a portion of the CO2 generated during the BF process into CO, subsequently reintroduced into the BF. This electrochemical process generates H2 and O2, thereby facilitating the reduction and oxygen enrichment of iron ore. However, the overall process entails high-energy consumption and necessitates the support of renewable energy sources. Research indicates that the integration of the CO2 electrolysis conversion process into the traditional BF operation can lead to a reduction in coke consumption from 386 kg/t to 260 kg/t at an oxygen enrichment level of 9%, resulting in a potential 40% reduction in CO2 emissions. Furthermore, the University of Birmingham in the UK has proposed a thermochemical BF-BOF coupling CO2 conversion CO cycle carbon reduction process [45]. This innovative approach utilizes a specialized catalytic material, Ba2Ca0.66Nb0.34FeO6 (BCNF), for the external conversion of CO2 into CO, which is subsequently reintroduced into the BF. This method enables the direct conversion of CO2 into O2 and CO, and it is anticipated to reduce CO2 emissions by nearly 90%.
In conclusion, a BF can achieve a reduced consumption of fossil fuels and lower carbon emissions to varying degrees through three carbon reduction pathways. The integrated application of a comprehensive low-carbon smelting process is projected to achieve a carbon emission reduction effect of up to 50%. These innovative technologies provide crucial support for the sustainable development of the steel industry. With the urgent need to achieve carbon neutrality goals, research and application of low-carbon smelting technologies for BFs will continue to be a focal point in the steel industry’s development, making a positive contribution to carbon emission reduction targets.

4. Comparison of Different BF Technological Pathways and Development Suggestions

The author analyzes the economic viability and developmental potential of the three carbon reduction pathways (source stage, process stage, and end stage) mentioned above and provides development pathway recommendations for achieving carbon neutrality in the steel industry. Given the heightened complexity and uncertainty in the current global economic environment, the steel industry faces multiple challenges, including shrinking demand, price pressures, rising costs, and reduced profits. This severely limits operational space for steel enterprises, making the adoption of high-cost low-carbon technologies a significant burden. Only low-cost and highly efficient decarbonization technologies can be widely promoted and rapidly adopted within enterprises.

4.1. Biomass Fuel Cost and Emission Reduction Capacity

In terms of availability, supply stability, and cost competitiveness, biochar offers advantages over H2. Although the carbon emission reduction technology of BF smelting with biochar instead of pulverized coal/coke has significant advantages, so far, due to the difficulties in the collection, storage, and transportation of biomass, the cost of biomass-based fuels is high, and there are few engineering demonstration projects. Common biomass-based fuels include charcoal, biocoal gas, bio-oil, biohydrogen, and biomethanol. The processing methods of different biomass-based fuels are also different. Table 3 shows the cost assessment of different biomass production processes.
In integrated steel plants, biochar can be applied in multiple steps, such as coking, sintering, and BF ironmaking. Using it as a material for BF injection can maximally reduce CO2 emissions by 19–28%, and the net CO2 reduction throughout the smelting process can reach 28–52%. SUOPAJÄRVI H N et al. [54] found that a partial substitution of fossil fuels with wood charcoal in BF injection can achieve a reduction in CO2 emissions by 15.4% to 26.4%. WANG C et al. [55], through simulation, demonstrated that wood charcoal has the potential to completely replace coal powder, resulting in a 28.1% reduction in emissions.
Table 4 provides a summary of research on biochar partially replacing pulverized coal for injection into a BF. Despite the clear advantages of using biochar for BF injection in carbon emission reduction, there are currently some challenges. In addition to the high cost and difficulties in collection, storage, and transportation, its poor grindability and high alkali metal content will further increase processing costs.
With the adjustment of national policies, the increasing trend of carbon tax price in the future will inevitably bring about a turnaround in the application of biochar. CRISTIBAL F B [60] conducted an analysis of the economic viability of co-injecting biochar and coal powder in BFs, suggesting that the carbon tax price could become a driving force for the use of biochar in BFs. On the economical perspective, if Bio-PCI would completely substitute coal PCI, an increment between 5% and 16% of cost would occur. The study indicates that biochar would only demonstrate cost competitiveness in the Chinese market if its price falls below 942.2 CNY/t (134.6 USD/t; according to the fact that USD 1 is equivalent to CNY 7, the following text is the same), meaning there is still a 50% cost reduction potential. In a scenario where actual processing costs and the market price of biochar remain unchanged, it is projected that in order for biochar to be economically competitive, the required carbon tax price should exceed 487.9 CNY/t (69.7 USD/t).

4.2. Economy of Hydrogen-Rich Fuel Injection

Given the accessibility and technical feasibility of hydrogen-rich fuels coupled with their relatively low BF retrofit costs, injecting hydrogen-rich fuels into BF is regarded as a bridge to advancing low-carbon metallurgical processes in the near term. This method has the potential to achieve carbon emission reductions ranging from 10% to 30%, presenting a pathway for decarbonization by substituting hydrogen-rich fuels for carbon-based reductants. However, its economic feasibility remains a critical constraint in the development of hydrogen metallurgy within the steel industry, particularly influenced by H2 production costs and carbon trading prices.

4.2.1. Carbon Market Regulation

At various stages of development, carbon pricing has been a crucial instrument in promoting low-carbon advancements and demonstration applications within the steel industry. Currently, there are 36 emission trading systems (ETS) operating worldwide, covering over 18% of global greenhouse gas emissions. The status of major international carbon trading systems is detailed in Table 5.
It is evident that the UK and EU carbon markets have the highest carbon prices, while China’s carbon market prices are relatively low. Among the major global carbon markets, the EU holds a dominant position. Since 1 October 2023, the EU has initiated the trial operation of the Carbon Border Adjustment Mechanism (CBAM), marking the EU as the first global economic entity globally to implement a “carbon tariff”.
China’s carbon market [62] represents the largest volume among global carbon markets in terms of covered emissions. As of 2023, cumulative transactions in China’s carbon market reached 442 million tons of carbon emission quotas, with a total turnover of CNY 24.919 billion. By June 2024, carbon prices in the Chinese market showed a stable upward trend, trading at approximately 90 CNY/tCO2. With current trends, this price is expected to reach around CNY 200 by 2030. In 2023, China’s crude steel production totaled 1.019 billion tons, with carbon emissions approximately at 1.834 billion tons. As national carbon tax policies are implemented in the steel industry, they will further increase manufacturing costs for Chinese steel enterprises. Given that steel is a foundational material in industrial manufacturing, widely used in downstream sectors such as construction, machinery, transportation, household appliances, and shipbuilding, the impact of future carbon prices may lead downstream industries to favor lower-carbon steel. This governmental and downstream industry-driven approach will compel the Chinese steel industry to seek more efficient carbon reduction measures.
The primary distinction between carbon taxes and carbon markets lies in the uncertainty surrounding emission reductions and carbon pricing. A carbon tax is a price-based policy where tax rates are set by regulatory authorities, while emission reductions are market determined. In contrast, carbon markets operate as quantity-based policies where authorities establish total emission allowances and market forces determine carbon prices. Despite the current preference for carbon markets in most countries, the combination of carbon market and carbon tax will be the mainstream means of government emission control management in the future. In order to simplify the model, this paper regards the carbon trading price as the product carbon tax price and conducts an equivalent cost scenario analysis.

4.2.2. Hydrogen Production Cost

H2 plays a crucial role in achieving carbon reduction targets within the steel industry as a clean energy source. Currently, the main sources of H2 include grey H2 (derived from fossil fuels/COG) and green H2 (produced via electrolysis powered by renewable electricity). In 2022, China’s H2 production totaled 37.81 million tons, with grey H2 accounting for approximately 95% of the total output. Incremental H2 consumption in the industrial sector, particularly from the steel industry, drives demand growth. According to the report of White Paper on China’s Hydrogen Energy and Fuel Cell Industry, it is projected that by 2050, China’s H2 demand will approach nearly 60 million t, with green H2 comprising 70% of the total.
Currently, Chinese enterprises favor the use of COG for the hydrogen-rich operation of BFs. Studies suggest that hydrogen-enriched reduction can achieve cost advantages comparable to traditional BFs when ample COG is available [63]. In 2023, China’s total COG production reached approximately 210 billion m3, accounting for over half of global output, and about 50%, or around 100 billion m3, of this can be utilized as a H2 source in the steel industry. Contrastingly, most low-carbon steel projects in Europe, such as HYBRIT and SALCOS, employ green H2 for production, sourced from dedicated green H2 supplies.
The cost analysis of H2 production processes from different feedstocks [64] is depicted in Figure 4. Currently, grey H2 has the lowest cost (9.0–13 CNY/kg). In contrast, other H2 production technologies incur higher costs due to expensive raw materials, averaging around 20 CNY/kg. Among these, water electrolysis exhibits the highest production cost, calculated at 27 CNY/kg based on current electricity prices of 0.4 CNY/(kW·h).
The decarbonization potential of hydrogen metallurgy largely depends on the source of H2. From a technological perspective, with grey H2 production, due to its high greenhouse gas emissions during processing, the carbon reduction effect of replacing fossil fuels cannot be achieved. The most promising H2 production technology is green H2 produced by electrolyzing water with renewable electricity. Therefore, the main source of hydrogen-based smelting in the future should be the combination of green H2, gray/blue H2, and the comprehensive application of CCUS technology.
In 2023, China’s renewable energy electricity generation reached 3 trillion kWh, accounting for approximately one-third of total societal electricity consumption. With advancing technologies, the cost of green electricity sourced from renewable energy is expected to decrease, thereby enhancing the cost competitiveness of H2 production. Based on current BF ironmaking costs, estimating the cost of H2 for steel industry reduction replacing carbon, the corresponding green electricity price should be around 0.1 CNY/(kW·h). This target is anticipated to be achievable by no later than 2050.

4.2.3. Low-Carbon Smelting Cost of BF Process

At present, the international advanced BF fuel consumption level remains around 500 kg/t. Assuming a coke ratio of 350 kg/t and a coal ratio of 150 kg/t, which are unchanged. Based on theoretical research on the skeletal function of coke, it is recommended that the minimum coke ratio in BF should be around 250 kg/t [39]. Under the aforementioned baseline conditions, the maximum amount of coke that can be replaced by low-carbon hydrogen-rich fuels is 350 − 250 = 100 kg/t. The authors made assumptions on fuel prices based on the average annual market prices in 2023: coke priced at 2000 CNY/t and pulverized coal priced at 1000 CNY/t, with a carbon emission intensity of 1.61 tCO2/t. Consequently, the fuel cost for traditional BF smelting is 0.35 × 2000 + 0.15 × 1000 = 850 CNY/t. When factoring in the current carbon tax trading price of 90 CNY/tCO2, the emission cost totals 1.61 × 90 = 144.9 CNY/t. Therefore, the combined cost of fuel and carbon emissions amounts to 994.9 CNY/t. A comparative analysis of smelting costs for various processes was conducted by the referenced literature on the substitution ratio of low-carbon fuels for coke [65,66], with detailed calculation results presented in Table 6.
As shown in Table 6, the current coke oven gas injection has a cost advantage, which is in good agreement with the current research status. Based on the current carbon tax of 90 CNY/tCO2, it can be seen that the injection of gray H2 has a cost advantage over traditional BFs. To make the injection of green H2 into a BF cost-effective, the cost of H2 should be 10 CNY/kg, and the estimated electricity price to achieve this level should be 0.1 CNY/(kW·h), which is also in good agreement with the estimated price. By plotting partial data from Table 6, a relationship between BF smelting costs and carbon tax prices at different time periods was obtained, as shown in Figure 5.
As shown in Figure 5, the comprehensive costs of both a traditional BF and BF with green H2 injection increase gradually with the growth of carbon taxes. As the cost of green H2 production decreases, the fuel price for green H2 injection in a BF also decreases. By 2040, it is estimated that the carbon tax will reach 400 CNY/tCO2, the green electricity price will drop to 0.2 CNY/(kW·h), and the green H2 cost will be 15.5 CNY/kg. Under these circumstances, the cost of a BF with green H2 injection will be 1492 CNY/t, equal to that of a traditional BF, indicating that the advantage of green H2 injection in a BF will begin to emerge in 2040. When the electricity price reaches 0.1 CNY/(kW·h) in 2050, the cost of green hydrogen smelting in a BF can reach the same level as a traditional BF without considering carbon taxes.
In summary, in the short term, the injection of coke oven gas and gray H2 can be adopted for hydrogen-rich smelting in a BF. With the gradual increase in carbon taxes and the decrease in green electricity prices, by around 2040, the injection of green H2 into a BF will begin to demonstrate cost advantages, marking an opportunity for the large-scale development of green hydrogen smelting in a BF. By 2050, after long-term development, the carbon reduction potential of green hydrogen smelting in a BF will gradually reach saturation, with both its operating costs and green H2 production costs generally decreasing. At this juncture, in combination with other decarbonization technologies, BF green hydrogen smelting is poised to achieve carbon neutrality goals, thereby making significant contributions to the sustainable development of the steel industry. By 2040, it is anticipated that BF H2 enrichment technologies will see initial adoption in ironmaking processes, with an estimated market penetration rate of approximately 13%, reaching mainstream status in iron smelting by 2050. Therefore, this new technology may not be suitable for global improvement, especially in the next ten years. Of course, each technology will exert its greatest strengths in specific scenarios (such as sufficient and stable biomass resources and cheap green hydrogen supply chains), and its cost advantages will gradually emerge.

4.3. Economy and Potential of Terminal Carbon Fixation Technology

Currently, there are 196 commercial CCUS facilities globally with a combined capture capacity exceeding 240 million tCO2/a. Throughout the steel production process, spanning from upstream mining, coal chemistry, coke making, H2 production, and electricity generation to steel smelting, these industries are significant sources of carbon emissions, underscoring the necessity for implementing CCUS emission reduction technologies. Within the CCUS process, capture is the most expensive and energy-consuming element, with China’s overall capture costs positioned at a mid-to-low global level. Notably, the carbon capture costs associated with China’s integrated coal and petrochemical industry-led oil displacement demonstration projects are exceptionally economical, ranging from 105 to 250 CNY/t, whereas other industries range between 200 and 730 CNY/t. These overall costs are consistently lower than the international average, which spans from 350 to 1280 CNY/t [67], underscoring China’s competitive edge in this regard. Moreover, installing CO2 capture and storage equipment with an annual capacity of 100,000 tons at a steel plant requires an investment of CNY 189 million (USD 27 million), while launching a 500,000 t/a CCUS project at Baowu Group Zhanjiang required an investment of CNY 364 million (USD 52 million), the economic evaluation conducted by the Baowu Group Plant showed that the total emission reduction cost was 455 CNY/t (65 USD/t).
At this stage, in terms of the cost of demonstration projects that have been put into operation, the cost of CCUS demonstration projects is higher, but the cost will be greatly reduced in the foreseeable future. By 2030, costs for both chemical and physical capture could potentially reach a target of 140 CNY/t (20 USD/t) [68,69,70]. When capture costs fall below carbon prices, CCUS technologies will seize substantial development opportunities. Under China’s dual-carbon goals, CCUS is expected to achieve nearly 24 million t/a in carbon reductions by 2025, growing to 100 million t/a by 2030, and reaching approximately 2 billion t/a by 2050 [67]. By 2050, CCUS technology is forecasted to deliver about 21% of carbon emission reductions for the steel industry.
In the steel industry, there are relatively few CCUS projects. As of 2023, major demonstration projects are listed in Table 7. One of the representative CCUS projects in China’s steel industry is Baogang Group’s 2 million tons CCUS integrated demonstration project. The first phase of the 500,000-ton demonstration project has commenced construction, and upon completion, it is expected to achieve an annual CO2 emission reduction of 365,300 tons. Currently, there exists a considerable gap between the development level of CCUS in China’s steel industry and the level required for commercialization at scale. Demonstrated capture costs are relatively high, leading to poor economic viability. However, looking ahead, as carbon prices rise and CCUS technologies mature, costs are expected to decrease, gradually showcasing the application value of CCUS.
If we want to deploy CCUS technology on a large scale in the steel industry, there are only two options: government intervention and market elimination. Government intervention refers to the mandatory deployment of CCUS equipment on the grounds of restricting carbon emissions. Market elimination refers to the high carbon tax policy, which leads to increased production costs due to carbon emissions.

4.4. Development Suggestions

4.4.1. Short-Term Development Proposals

From a technological perspective, grey H2 cannot replace fossil fuels due to its high greenhouse gas emissions. Therefore, the primary direction for future hydrogen-rich smelting in BFs should involve combining green H2 injection with CCUS. In the short term, given considerations of asset preservation, technological maturity, and carbon reduction potential, emphasis should be placed on the development of deep decarbonization technologies based on existing BF processes, such as injecting hydrogen-rich fuels like coke oven gas- and coal-derived syngas, which can directly and effectively reduce carbonaceous fuel consumption and subsequently mitigate CO2 emissions, representing the most direct and effective technical measures currently available.

4.4.2. Medium-Term Development Proposals

Continued research and development should be pursued for cutting-edge technologies such as green H2, biochar smelting, and CCUS, while reinforcing the breakthroughs in key low-carbon BF smelting technologies based on existing technologies. This will further reduce the consumption of carbon-based fuels in BFs and minimize CO2 emissions. Through a combination of policy guidance, market incentives, and international cooperation, constructing effective business models to lower investment and operational costs of low-carbon technologies, initiating demonstration projects of low-carbon BF smelting technologies should be initiated to achieve large-scale development of low-carbon BFs. Facilitating the market-oriented transformation of technological achievements is a crucial pathway towards realizing the low-carbon transformation of BFs and mitigating CO2 emissions.

4.4.3. Long-Term Development Proposals

The gradual phase-out of technologically outdated BFs with high emissions, which are reaching the end of their operational lifespan and unsuitable for retrofitting, is advocated, actively promoting pure hydrogen-based reduction technology. This necessitates accelerating the industry-wide integration of the traditional BF-BOF long process towards a smarter, more productive, and efficient steel sector. Collaborating with green electricity and hydrogen suppliers, steel enterprises are forging an industrial chain ecosystem to achieve synergistic development. Moreover, the integration of a comprehensive low-carbon smelting process, encompassing biomass-based decarbonization at the source, hydrogen-rich decarbonization during the process, and end-stage CCUS for carbon fixation, is paramount. This approach involves minimizing carbon input through the substitution of biomass fuels and green H2, while concurrently reducing carbon output through the application of CO2 separation, capture, and utilization technologies. By addressing the entire spectrum—from the source, through the process, to the end—a holistic approach to achieving low-carbon and green development in BF ironmaking can be realized, ultimately reducing overall carbon emission intensity by over 50%.

5. Conclusions

In this paper, a comprehensive low-carbon metallurgical process concept with the substitution of carbon-neutral biomass fuels at the source stage—intensification of hydrogen enrichment in the process stage—fixation of CCUS at the end stage (SS-IP-FE) was proposed, and critical elements were analyzed, assessing their cost-effectiveness and emission reduction potential, underscoring comprehensive low-carbon metallurgy as a pivotal direction for future steel industry development with high technological feasibility and emission reduction efficacy. Based on the above description, the following conclusions are summarized:
(1)
The current global steel production still heavily relies on the BF ironmaking technology. The deep decarbonization technologies within the BF long process will play a pivotal role in supporting the development of near-zero-carbon steel in the future, serving as a crucial transitional solution for the steel industry to achieve carbon neutrality. While the BF process may not fully decouple from coal and coke dependence in the short term, the integration of advancing technologies such as CCUS, alongside the gradual adoption of green H2 production and biomass fuel preparation, holds promise for achieving profound decarbonization within the BF process. The comprehensive application of various low-carbon smelting technologies will provide a comprehensive solution towards realizing carbon neutrality targets within the steel sector. This multifaceted approach ensures a transition towards cleaner and more sustainable steel production practices.
(2)
The international efforts in BF low-carbon engineering projects are currently summarized as being predominantly in the industrial experimentation phase. It is deemed that hydrogen enrichment in BF processes represents the preferred direction for current low-carbon development. However, its carbon emission reduction potential is limited, achieving reductions of only 10% to 30% in CO2 emissions, insufficient for fundamentally addressing BF carbon emissions. The future direction advocates transitioning traditional BFs towards comprehensive low-carbon processes, which include technologies such as biomass carbon reduction at the source, midstream hydrogen-rich fuel injection for decarbonization, and end-point carbon capture, utilization, and storage (CCUS).
(3)
Despite the significant decarbonization potential demonstrated by new fuels such as H2 and biochar, their high costs in production, storage, and application, along with the unclear competitive advantage of CCUS technology compared to other emission reduction techniques, have resulted in limited implementation of BF low-carbon demonstration projects in steel enterprises. To foster the widespread adoption of low-carbon technologies, intensified research and development efforts are imperative, along with the establishment of effective business models that can mitigate investment and operational costs, thereby facilitating the commercialization of technological achievements. Policy guidance, market incentives, and international cooperation can stimulate international investment in low-carbon technologies, creating a virtuous cycle. These efforts aim to propel the steel industry towards more environmentally friendly and sustainable practices.

Author Contributions

Conceptualization, H.L. and Y.Z.; curation, C.G.; Funding acquisition, H.L.; Investigation, H.L.; Methodology, H.L. and Y.Z.; Project administration, H.L.; Resources, H.L.; Software, J.L.; Supervision, H.L.; Writing—original draft, C.G.; Writing—review and editing, H.L., Y.Z. and J.L. All authors have read and agreed to the published version of the manuscript.

Funding

Financial support was provided by the National Key R&D Program of China (No. 2022YFE0208100).

Data Availability Statement

No new data were created or analyzed in this study. Data sharing is not applicable to this article.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Process of oxygen BF with hydrogen-enriched and carbon recycling.
Figure 1. Process of oxygen BF with hydrogen-enriched and carbon recycling.
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Figure 2. A roadmap of the low-carbon ironmaking process for the whole process.
Figure 2. A roadmap of the low-carbon ironmaking process for the whole process.
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Figure 3. CO2 capture technology and application in the long process of the BF-BOF.
Figure 3. CO2 capture technology and application in the long process of the BF-BOF.
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Figure 4. Comparative analysis of cost and CO2 emissions of common hydrogen production technologies.
Figure 4. Comparative analysis of cost and CO2 emissions of common hydrogen production technologies.
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Figure 5. Relationship between BF cost and carbon tax price in different periods.
Figure 5. Relationship between BF cost and carbon tax price in different periods.
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Table 1. Summary of international typical BF low-carbon projects.
Table 1. Summary of international typical BF low-carbon projects.
CountryProjectFuel TypesOverview of DetailsTRL *
JapanCOURSE50 [9,10,11]COGDecarbonizing and recycling of top gas, injecting it from the lower or shaft tuyere, achieves a 30% carbon reduction. Hydrogen reduction contributes 10%, while CCUS technology accounts for 20%TRL8
Super-COURSE50H2Through the combined methods of external hydrogen and CCUS technology, a projected CO2 reduction of 50% is expected, with a current achievement of 22% reduction. Widespread adoption is anticipated by around 2050TRL7
BF with
carbon recycling [12]		CH4Converting CO2 of blast furnace gas (BFG) into methane for repeated use as a reducing agent is expected to achieve a CO2 reduction of over 50%. JFE plans to construct a 150 m3 small-scale carbon recycling BF for experimentation by 2025TRL6
GermanyThyssenkrupp replaces coal with hydrogen [13]H2Trials of injecting H2 into BFs commenced in 2019, gradually extended to three other BFs by 2022, resulting in a 20% reduction in CO2 emissionsTRL8
Hydrogen ironmaking in Dillingen and Saar steel [14]H2-enriched fuel gas
(COG)		COG is utilized as a reducing agent, with continuous injection starting in 2020. The plan aims to reduce CO2 emissions by 40% by 2035TRL8
Blue BF in SMSH2-enriched fuel and Syngas (CO and H2)Injecting hydrogen-rich fuel at the hearth tuyere and inject syngas at shaft tuyere can achieve a 28% reduction in CO2 emissions. However, it requires the addition of an external reformerTRL7
EUULCOS [15]Recycling top gasAdopting the Top Gas Recycling Blast Furnace (TGR-BF) can reduce CO2 emissions by approximately 50%. Trials were conducted by LKAB company in 2007 and SSAB company in 2012TRL9
Note: * TRL (Technology Readiness Level): A standard for measuring and evaluating the level of technological maturity. The maturity level of technology has different standards in different regions and fields. The current common practice is to divide it into 9 levels [16], which are TRL1 discovering basic principles, TRL2 forming technical solutions, TRL3 key functions being analyzed and experimented with, TRL4 forming units and being validated, TRL5 forming component systems and being validated, TRL6 forming prototypes and being validated, TRL7 having real-world applications, TRL8 having user validation, and TRL9 being promoted and applied.
Table 2. Low-carbon BF engineering projects in China.
Table 2. Low-carbon BF engineering projects in China.
CompanyTimeRoutesFuel TypesOverview of DetailsTRL
Baosteel of Baowu Group2020Hydrogen-rich BFNature gasNo.1 BF of Baosteel [18]: The natural gas injection volume is 60~65 m3/t, with solid fuel reduced by about 10%. The utilization rate of CO remains at 49%, and H2 utilization rate reaches 43% TRL8
Bayi Steel of Baowu Group2022–2023Oxygen BF with carbon recycling (HyCROF)Recycling top gasIndustrialization trial in 2022 [19]: 100% oxygen enrichment, solid fuel reduced by 30%, and carbon reduced by over 21%.Commercial demonstration project in 2023: It was launched with an annual CO2 emission reduction of 1 Mt TRL8
Shanghai
University		2021Hydrogen-rich BFH2Experimental BF of 40 m3 [20]: The H2 injection rate is 1800 m3/h (250 m3/t). The coke ratio is reduced by 10%, CO2 emissions are reduced by 10%, and hot metal production is increased by 13% TRL7
Jinnan Steel Group2021Oxygen BF with carbon recyclingCoke oven gas1860 m3 BF [21]: H2 utilization rate is 35~40%, and CO utilization rate is 40~45% after injecting hydrogen-rich gas; CO2 emissions are reduced by around 80 kg/t, injecting 65 m3/t of COG, and the fuel ratio can be reduced by 32 kg/tTRL8
CISDI2023C-H Reducing, Reusing and Recycling BF (3R-BF)Reducing gas with H2/CO2300 m3 BF [22]: Fuel ratio is reduced by 20~30 kg/t, with a coke reduction by 5~8 kg/t, average gas replacement ratio ranges from 0.35 to 0.6 kg/m3, carbon reduction of around 10%, hot metal production increased by 3%, and cost reduced by 10~30 CNY/t TRL8
HBIS Group2023RSF with carbon recycling and Hydrogen-richGreen H2New Designing route [23]: Combining top gas decarbonization and hydrogen-rich gas heating to achieve process gas self-circulation, theoretically breaking the traditional BF’s 70% limit for the metallization rate in upper part, and aiming to achieve a reduction in CO2 emissions by 44~69% per ton of steel. Industrial trials are expected to be realized by 2024 TRL6
Taishan Steel Group2020Tradition BFCO2Industrial application [24]: Injecting CO2 can reduce the RATF and meanwhile increase the oxygen-enriched rate and coal rate, which can achieve increased the production of BFs. The average mass of CO2 injection per day reaches 100 t TRL8
Shougang Group2023Tradition BFBiocharInjection test of 2650 m3 BF [25]: The maximum injection amount of biochar is above 10 kg/t, with a single tuyere injection amount exceeding 2.4 t/h.TRL7
Table 3. Different biomass fuel preparation costs, adapted from Ref. [53].
Table 3. Different biomass fuel preparation costs, adapted from Ref. [53].
Types of BiocharPreparation MethodProductCost/(CNY·t−1)Country
Forest residuesGasification + upgradingBiomethane1672.5Canada
GasifierBiomass hydrogen6675.0
Gasification/methanationBiomass gas5415.0Finland
Slow pyrolysisCharcoal2827.5
Miscanthus anderssFast pyrolysisBio-oil1230.0USA
EucalyptusSlow pyrolysisCharcoal2272.5Australia
Table 4. Current status of emission reduction by injecting biochar.
Table 4. Current status of emission reduction by injecting biochar.
Types of BiocharTechnologyInjection Rate/(kg·t−1)Theoretical CO2 Saving Potential/(kg·t−1)References
StrawPyrolytic11.3765.7[56]
StrawHydrothermal90145.7[57]
Palm shellPyrolytic3084.65[58]
WoodPyrolytic100315[59]
WoodPyrolytic140~429[29]
SawdustShallow roasting140~195[29]
Table 5. The development status of major international carbon trading systems, adapted from Ref. [61].
Table 5. The development status of major international carbon trading systems, adapted from Ref. [61].
Carbon Trading SystemStart TimeTotal Quota Amount/(Mt CO2)Carbon Price/(CNY·t−1)Quota Allocation Method
EU20051486623Auction plus free
New Zealand200832.3252Auction plus free
USA2012294.1231Auction plus free
South Korea2015589.363Auction plus free
UK20211366455Auction plus free
China2021450077Free of charge
Table 6. Comparison of coke replacement ratio and metallurgical cost of low carbon fuel.
Table 6. Comparison of coke replacement ratio and metallurgical cost of low carbon fuel.
Fuel TypeCOGNGGray H2Green H2 2025Green H2 2030Green H2 2035Green H2 2040Green H2 2045Green H2 2050
Replace Ratio/(kg·kg−1)0.911.185555555
Injection amount/(kg·t−1)109.984.7520.020.020.020.020.020.020.0
Price of fuel/(CNY·t−1)1200357011,00027,00021,000180,0015,50012,50010,000
Cost of fuel/CNY·t−1)781.88952.55870119010701010960900850
CO2 emission/(t·t−1)1.451.511.331.331.331.331.331.331.33
Price of CO2/(CNY·t−1)909090100200300400500600
Comprehensive BF cost/(CNY·t−1)912.41088.4989.7132313361409149215651648
Tradition BF cost/(CNY·t−1)994.9994.9994.9101111721333149416551816
Table 7. CCUS demonstration projects in the steel industry.
Table 7. CCUS demonstration projects in the steel industry.
CasesApplication TargetCapture Method
COURSE50 project in JapanBlast furnace gasChemical Absorption
(organic amine)
Physical Absorption (PSA)
POSCO carbon capture project in KoreanBlast furnace gasChemical Absorption (Ammonia)
Whole process CCUS project of UAE Steel CompanyShaft furnace gasChemical Absorption (Ethanolamine)
ArcelorMittal Ghent blast furnace carbon capture projectBlast furnace gasChemical Absorption
2 Million tons CCUS demonstration project of Baogang GroupIndustrial exhaust gas—
Ouye furnace gas carbon capture project of Baowu GroupOuye furnace gasChemical Absorption
(organic amine)
Lime kiln gas CO2 capture project of Shougang GroupLime kiln gasPhysical Absorption (PSA)
Hydrogen energy development and utilizationdemonstration project of HBIS GroupShaft furnace gasChemical Absorption
(organic amine)
COG carbon capture demonstration project of China RISUN GroupCoke oven gasChemical Absorption
(organic amine)
CCUS capture and resource utilization project of Ningbo SteelLime kiln gasChemical Absorption
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Li, H.; Zhao, Y.; Guo, C.; Li, J. Analysis of Technological Pathways and Development Suggestions for Blast Furnace Low-Carbon Ironmaking. Metals 2024, 14, 1276. https://doi.org/10.3390/met14111276

AMA Style

Li H, Zhao Y, Guo C, Li J. Analysis of Technological Pathways and Development Suggestions for Blast Furnace Low-Carbon Ironmaking. Metals. 2024; 14(11):1276. https://doi.org/10.3390/met14111276

Chicago/Turabian Style

Li, Haifeng, Yan Zhao, Chengqian Guo, and Junqi Li. 2024. "Analysis of Technological Pathways and Development Suggestions for Blast Furnace Low-Carbon Ironmaking" Metals 14, no. 11: 1276. https://doi.org/10.3390/met14111276

APA Style

Li, H., Zhao, Y., Guo, C., & Li, J. (2024). Analysis of Technological Pathways and Development Suggestions for Blast Furnace Low-Carbon Ironmaking. Metals, 14(11), 1276. https://doi.org/10.3390/met14111276

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