Cite this article as: |
Xin Lu, Weijian Tian, Hui Li, Xinjian Li, Kui Quan, and Hao Bai, Decarbonization options of the iron and steelmaking industry based on a three-dimensional analysis, Int. J. Miner. Metall. Mater., 30(2023), No. 2, pp. 388-400. https://doi.org/10.1007/s12613-022-2475-7 |
卢鑫 E-mail: xin.lu.a5@tohoku.ac.jp
白皓 E-mail: baihao@metall.ustb.edu.cn
Decoupling CO2 emissions from economic development has become a significant issue that must be addressed to meet the challenges posed by the worldwide carbon crunch, particularly for China [1–2]. China has started a nationwide carbon reduction policy and emission trading scheme to help deliver its emission peak by 2030 [3]. Under such a background, there is a pressing need to promote decarbonization for energy-intensive industries, such as ferrous and non-ferrous metallurgy, cement production, and thermal power generation [4].
As a typical energy-intensive industry, worldwide production of iron and steel leads to a total annual energy consumption of about 40 EJ (i.e., 1018 J) (6% of the global energy used) and CO2 emissions of about 3.7 GJ (i.e.,109 J) (25% of industrial CO2-equivalent emission) [5]. In 2021, China produced 1032.8 Mt (i.e., million tons) of crude steel, which is 52.9% of the world’s total production [6]. Consequently, China’s iron and steel industry is responsible for approximately 15% of the national energy consumption [7] and emits approximately 16% of the country’s annual CO2 emissions [8].
The options to reduce the CO2 emissions of the ironmaking–steelmaking process have been attracting significant attention. In most cases, three options—promoting energy efficiency or energy conservation [9–18], energy substitution [19–23], and process substitution [22–28]—are the subject of focus for CO2 emission reduction. The most common option for CO2 emission reduction is promoting energy efficiency by applying energy conservation technologies in the iron and steel industry [9–16]. Currently, 70.8% of crude steel is produced by the blast furnace–basic oxygen furnace (BF–BOF)-based integrated process worldwide, while in China, 89.4% is from this integrated process [6]. The energy structure of the conventional ore-based BF–BOF process has poor flexibility because carbon-based coke/coal is the dominant energy source [29]. The application of energy conservation technologies in this process always works well for CO2 emission reduction. The cost-effective energy-saving potential for the Chinese iron and steel industry for 2030 has been estimated to be approximately 5.7 EJ, which would result in an emission mitigation of 463 Mt CO2 [30]. Obviously, effectively reducing CO2 emissions should be based on the conservation of carbon-based energy. In other words, the carbon content in the consumed energy or energy structure, for a technology or a process should change the CO2 emission reduction potential by applying energy conservation technologies.
Energy substitution to reduce the carbon content in the energy structure is another decarbonization option. High carbon-based energy used in the integrated process is substituted with a low-carbon or carbon-free form of energy [31–32], such as hydrogen [19–20,33–34], natural gas/syngas [35–36], biomass residues [37–39], electricity generated from renewable energy [40], and waste plastic materials [41–42]. This approach could substantially reduce CO2 emissions by decreasing the carbon ratio in the consumed energy. For this reason, energy substitution has been suggested as one of the most important measures to accelerate the decarbonization development of the iron and steel industry [43]. A recent report on the CO2 emission reduction strategy in the Brazilian iron and steel sector shows that switching to increased use of charcoal can provide the best cost-benefits for CO2 reduction [44].
Substituting the existing integrated process with processes that consume low-carbon energy is also attracting more attention [22–27]. Development of the scrap-based electric arc furnace (EAF) process is greatly encouraged [45–46]. Considerable efforts have also been made to develop new processes, such as the direct reduction iron (DRI) process, the smelting reduction iron (SRI) process, the “Ultralow CO2 Steelmaking” (ULCOS) project in Europe, and the “CO2 Ultimate Reduction in Steelmaking Process by Innovative Technology for Cool Earth 50” (COURSE 50) project in Japan, which promotes the utilization of new types of energy such as natural gas or hydrogen [22–23,26–27].
Both energy substitution and process substitution will result in a much more complicated and variable energy structure of the total ironmaking–steelmaking process [22,27]. With such a background, the decarbonization potential and effects of energy conservation will change. Fig. 1 shows one of the examples of the effect of the energy structure on the CO2 emission reduction. The relationship between energy saving potential and the corresponding CO2 emission reduction potentials of various technologies in different processes and countries is shown in Fig. 1(a) and (b), respectively [47–49]. As shown in Fig. 1(a), the correlation between energy saving potentials and CO2 emission reductions is not always linear and is scattered in different processes. Meanwhile, Fig. 1(b) shows that the application of energy-saving technologies in the integrated process has a higher CO2 emission reduction potential than that in the EAF process in China, while the effects of energy-saving technologies in the integrated process and the EAF process are similar in the US. This result might be attributed to the larger share of natural gas used in the integrated process in the US (28% in the studied year [49]) relative to that used in China, where little natural gas is used (approximately 80% of the energy is from coal) [45].
The energy structure, which highly influences CO2 emission reduction, should be fully considered when a decarbonization strategy is being developed. Thus, the relationship between energy structure and CO2 emissions in the iron and steel industry needs to be studied systematically. Many studies have been conducted based on carbon balance or carbon metabolism, and the decarbonization potential of different technologies or processes of ironmaking and steelmaking has been evaluated [22,26]. However, ironmaking and steelmaking is a highly coupled process of material flow and energy flow, and its carbon emissions should be related to resource consumption, energy consumption, and its corresponding energy structure. Therefore, a multidimensional carbon emission model needs to be established to clarify the root causes of carbon emission in the ironmaking and steelmaking processes to provide a basis for determining scientific emission reduction strategies.
In this study, a new factor called process general emission factor (PGEF) of CO2, which is defined as the ratio of the CO2 emissions and the corresponding energy consumed in a specific or the overall process, is proposed and used to evaluate the effect of the energy structure on CO2 emissions of the considered process. In the discussion of decarbonization options, PGEF was used to represent the energy. On the basis of the introduction of the PGEF, the decarbonization options of the ironmaking and steelmaking processes in China were systematically analyzed by considering resource utilization efficiency (Y), energy utilization efficiency (Q), and energy cleanliness which was evaluated by PGEF. Facility-level PGEF was first investigated, and then a systematic low-carbon analysis method considering PGEF, Y, and Q was applied for the current integrated process and alternative processes, including EAF, DRI, and SRI. Decarbonization options for China’s iron and steel industry were discussed, focusing on process substitution by comprehensively considering the above three-dimensional aspects. The systematic and quantitative three-dimensional results can be of significant reference to easily evaluate the decarbonization potential of the iron and steel industry with a variable process and energy structure. The three-dimensional method used in this paper is expected to extend to other energy-intensive processes or industries, such as the cement and thermal power industries.
The CO2 emissions of the integrated process were investigated as the first step of the low-carbon analysis. The CO2 emissions can be calculated easily based on the mass balance of the carbon input and output, as shown in Eq. (1). As a case study, statistical data from two practically integrated steel plants, plants A and B, were used. These data included the mass of the materials and the amount of energy that were input into or output from the specific processes. Plant A in North China and plant B in East China have approximately 8 and 13 Mt annual crude steel production scales, respectively, and all the crude steel in plant A is produced by the BOF process, while part of that in plant B is produced by the EAF process. The calculation boundary of the ironmaking and steelmaking processes is shown in Fig. 2.
$$ \begin{aligned} & {E}_{{\mathrm{C}\mathrm{O}}_{2}}={E}_{\mathrm{I}\mathrm{n}\mathrm{p}\mathrm{u}\mathrm{t},{\mathrm{C}\mathrm{O}}_{2}}-{E}_{\mathrm{O}\mathrm{u}\mathrm{t}\mathrm{p}\mathrm{u}\mathrm{t},{\mathrm{C}\mathrm{O}}_{2}}=\\ & \quad \sum _{x=1}^{M}{{\rm{\varOmega}} }_{\mathrm{I},x}\times {\mathrm{E}\mathrm{F}}_{\mathrm{I},x}-\sum _{y=1}^{N}{\varOmega }_{\mathrm{O},y}\times {\mathrm{E}\mathrm{F}}_{\mathrm{O},y} \end{aligned}$$ | (1) |
where
Generally, the default CO2 emission factors suggested by the Intergovernmental Panel on Climate Change were used. For the practical by-product gasses, including the blast furnace gas (BFG), the basic oxygen furnace gas (BOFG), and the coke oven gas (COG), their CO2 emission factors were calculated based on practical gas compositions from the plants. In addition, only the direct CO2 emission was considered from the viewpoint of cleaner production of the entire ironmaking–steelmaking process, the specific process, the specific equipment, and the indirect CO2 emission from the purchased electricity used was not within the scope of this study. The details of the calculation method were shown in previous studies [50–51].
The total CO2 emissions (Mt) and the CO2 emission intensity (defined as the amount of CO2 emissions per ton of crude steel production, t∙t−1) are shown in Fig. 3(a) and (b), respectively, for plants A and B. On average, 14 and 26 Mt CO2 were emitted annually from the crude steel production activities of plants A and B, respectively. Obviously, the total CO2 emissions increase with the increase in the annual crude steel production in each plant. However, the CO2 emission intensities vary and do not show a direct correlation with annual crude steel production mainly because the energy structure is variable in different plants and years, as further discussed below.
Fig. 4 shows the correlation between CO2 emission intensity and energy consumption intensity (defined as energy consumption per ton of crude steel production, GJ∙t−1) of plants A and B in different producing years. The heavy solid line, called the carbon saturation line, presents the upper limit of CO2 emission intensity based on the assumption that only pure carbon is consumed in the total process, while the heavy dashed line is the limitation of the CO2 emission intensity, representing that 80% pure carbon and 20% non-carbon energy (i.e., hydrogen) are consumed in the ironmaking–steelmaking process. The CO2 emission intensities in plants A and B ranged between the carbon saturation line and the 80% carbon line, which indicates that carbon is the dominant energy in the energy structure of the two steel works. In addition, the CO2 emission intensities for plant A were closer to the carbon saturation line than those for plant B, which is attributed to approximately 10% of crude steel being produced by the EAF process in plant B, whereas all steel products in plant A were from the integrated process. Thus, a higher electricity consumption ratio was observed in plant B, which resulted in lower direct CO2 emissions in the ironmaking–steelmaking process. Meanwhile, several fuels with various carbon/hydrogen ratios in addition to electrical power are used in ironmaking–steelmaking process. Therefore, considering the effect of the energy structure on the CO2 emissions in the low-carbon analysis of the ironmaking–steelmaking process is a crucial step.
For the ironmaking and steelmaking processes, both the input and output items shown in Eq. (1) or Fig. 2 can be classified as energy and non-energy items. The energy and non-energy items are different for specific processes. Typically, the energy items generally include coal or anthracite (coking, sintering, and BF processes), coke (coking, sintering, and BF processes), BFG (coking, sintering, pellet, BF, rolling, and flux calcination processes), COG (coking, sintering, BF, rolling, and flux calcination processes), BOFG (sintering, pellet, BOF process, rolling, and flux calcination processes), and power (for all the specific process). The non-energy items include tar and crude benzol (coking process), hot metal (BF and BOF processes), crude steel (BOF and rolling processes), and flux (flux calcination process).
Considering the characteristics of energy and non-energy items, Eq. (1) can be shown as Eq. (2) in more detail.
$$ {E}_{{\mathrm{C}\mathrm{O}}_{2}}=\sum _{i=1}^{m}{M}_{i}\times {\mathrm{E}\mathrm{F}}_{i}-\sum _{j=1}^{n}{M}_{j}\times {\mathrm{E}\mathrm{F}}_{j}+{M}_{f}\times {\mathrm{E}\mathrm{F}}_{f}-\sum _{k=1}^{p}{M}_{k}\times {\mathrm{E}\mathrm{F}}_{k} $$ | (2) |
The energy consumption can be calculated by Eq. (3).
$$ E=\sum _{i=1}^{m}{M}_{i}-\sum _{j=1}^{n}{M}_{j} $$ | (3) |
A new factor called PGEF is defined as the ratio of CO2 emissions and the corresponding energy consumption in a specific process or the overall process. To some extent, it reflects the cleanliness of the energy used in the process. PGEF can be calculated as follows:
$$ \mathrm{P}\mathrm{G}\mathrm{E}\mathrm{F}={E}_{{\mathrm{C}\mathrm{O}}_{2}}/E $$ | (4) |
Overall, PGEF is calculated as follows:
$$\begin{aligned}[b] & \mathrm{P}\mathrm{G}\mathrm{E}\mathrm{F}=\\ & \quad \frac{\sum _{i=1}^{m}{M}_{i}\times {\mathrm{E}\mathrm{F}}_{i}-\sum _{j=1}^{n}{M}_{j}\times {\mathrm{E}\mathrm{F}}_{j}+{M}_{f}\times {\mathrm{E}\mathrm{F}}_{f}-\sum _{k=1}^{p}{M}_{k}\times {\mathrm{E}\mathrm{F}}_{k}}{\sum _{i=1}^{m}{M}_{i}-\sum _{j=1}^{n}{M}_{j}} \end{aligned} $$ | (5) |
PGEF can be shown as Eq. (6) if the different items are divided as Eqs. (7)–(10).
$$ \mathrm{P}\mathrm{G}\mathrm{E}\mathrm{F}={E}_{\mathrm{I}}-{E}_{\mathrm{O}}+F-P $$ | (6) |
$$ {E}_{\mathrm{I}}=\frac{\sum _{i=1}^{m}{M}_{i}\times {\mathrm{E}\mathrm{F}}_{i}}{\sum _{i=1}^{m}{M}_{i}-\sum _{j=1}^{n}{M}_{j}} $$ | (7) |
$$ {E}_{\mathrm{O}}=\frac{\sum _{j=1}^{n}{M}_{j}\times {\mathrm{E}\mathrm{F}}_{j}}{\sum _{i=1}^{m}{M}_{i}-\sum _{j=1}^{n}{M}_{j}} $$ | (8) |
$$ F=\frac{{M}_{f}\times {\mathrm{E}\mathrm{F}}_{f}}{\sum _{i=1}^{m}{M}_{i}-\sum _{j=1}^{n}{M}_{j}} $$ | (9) |
$$ P=\frac{\sum _{k=1}^{p}{M}_{k}\times {\mathrm{E}\mathrm{F}}_{k}}{\sum _{i=1}^{m}{M}_{i}-\sum _{j=1}^{n}{M}_{j}} $$ | (10) |
where PGEF refers to the CO2 general emission factor, t∙GJ−1; E refers to the corresponding energy consumption, GJ; Mi, Mj, Mf, and Mk refer to the amounts of energy input i (GJ), energy output j (GJ), non-energy input f (t), and non-energy output k (t), respectively; EFi, EFj, EFf, and EFk refer to the CO2 emission factors of i (t∙GJ−1), j (t∙GJ−1), f (t∙t−1), and k (t∙t−1), respectively; m, n, and p refer to the number of i, j, and k, respectively; and EI, EO, F, and P refer to the impact of the items of the energy input, energy output, non-energy input, and non-energy output on the PGEF, respectively.
The non-energy input (F) is mainly in the form of limestone used as a flux for the sintering and steelmaking processes, and the main non-energy output (P) is the steel product. In most cases, ignoring the impacts of these two items, F and P, is reasonable in the calculation of PGEF. For example, in the case of plant A, the CO2 emissions due to the flux and products are only approximately 1% and 2% of the total CO2 emissions, respectively. With F and P ignored, PGEF is calculated as follows by combining EI and EO:
$$ \mathrm{P}\mathrm{G}\mathrm{E}\mathrm{F}={E}_{\mathrm{I}}-{E}_{\mathrm{O}}=\sum _{{\textit z}=1}^{m+n}{\mathrm{E}\mathrm{F}}_{\mathrm{E,{{\textit z}}}}\times \left(\frac{{{M}}_{\mathrm{E},{\textit z}}}{{\sum }_{{\textit z}=1}^{m+n}{M}_{\mathrm{E},{\textit z}}}\right)=\sum _{{\textit z}=1}^{m+n}{\mathrm{E}\mathrm{F}}_{\mathrm{E},{\textit z}}\times {X}_{\mathrm{E},{\textit z}} $$ | (11) |
where EFE,z refers to the CO2 emission factor of the specific energy z, t∙GJ−1; ME,z refers to the amount of the specific energy z (output energy is set as negative and input as positive); XE,z refers to the ratio of the specific energy z, in the total energy consumption. Thus, PGEF is transformed to be a function of the energy structure and the CO2 emission factors of the various energy sources if the total ironmaking–steelmaking process is considered.
With the introduction of PGEF, the CO2 emission intensity of the terminal products of ironmaking–steelmaking process (crude steel or the rolling mill products, in certain cases) is calculated as follows:
$$ {E}_{{\mathrm{C}\mathrm{O}}_{2},\mathrm{ }\mathrm{ }\mathrm{ }\mathrm{ }\mathrm{ }\mathrm{ }\mathrm{i}\mathrm{n}\mathrm{t}}=\sum _{i=1}^{X}{E}_{{\mathrm{C}\mathrm{O}}_{2},i}=\sum _{i=1}^{X}{Y}_{i}\cdot {\mathrm{P}\mathrm{G}\mathrm{E}\mathrm{F}}_{i}\cdot {Q}_{i} $$ | (12) |
where
Thus, the CO2 emission intensity of the terminal products depends on three factors: Yi, PGEFi, and Qi. The variable Yi indicates the resource utilization efficiency or production efficiency. For example, reducing iron losses during ironmaking and steelmaking, such as reducing in-house scrap generation or decreasing the iron content of slag or dust, would benefit carbon reduction. Reducing the Yi of pig iron in the steelmaking process by applying steel scrap as a replacement could also significantly decrease CO2 emissions because much of the total CO2 emissions are emitted from the production of pig iron by the BF [52]. The variable Qi indicates the energy utilization efficiency of each sub-process. Conventionally, the application of energy-saving technologies can significantly improve the effectiveness of Qi, which was discussed in detail in previous studies [10,47–49]. PGEFi reflects the content of the consumed energy, namely, the energy structure or energy cleanliness. The optimization of the energy structure by using low-carbon or carbon-free energy in novel processes would be effective for carbon reduction, which will be discussed in detail in Section 4. Thus, decarbonization of the ironmaking–steelmaking process depends on the optimization of the resource utilization efficiency (Y), energy utilization efficiency (Q), and energy cleanliness (PGEF).
As a case study, the PGEF of the integrated process in plants A and B were calculated, and the results are shown in Fig. 5. The PGEF in plants A and B are not constant, which indicates that the CO2 emissions might vary even with equivalent levels of energy consumption. This PGEF variability can be attributed to the energy structure fluctuation. The primary energy consumed in plant A includes coke, anthracite, and washed coal, all of which have higher overall impact factors (defined as the amounts of CO2 emissions per unit of energy by mass) than those of the energy consumed in Plant B. The higher overall impact factors cause the average PGEF of plant A to be higher than that of plant B. Meanwhile, coke and washed coal are the energy types with the highest overall impact factor in plants A and B, respectively, and their proportions in the energy structure of each plant are shown in Fig. 5. The fluctuation of PGEF is similar to that of the proportion of coke in plant A and washed coal in plant B.
According to Eq. (11), the energy structure indicated by XE should be optimized to reduce the PGEF. First, reducing the proportion of energy with a high overall impact factor is important. Thus, increasing the ratio of electricity or hydrogen-based energy would be greatly beneficial for PGEF reduction and subsequent CO2 emission reduction. Second, the proper reuse and treatment of social wastes, such as junked tires and waste plastics, would not only directly reduce their environmental pollution but also reduce the PGEF of ironmaking and steelmaking by reducing EI because of the much lower carbon content of these wastes [31,41]. Third, a large amount of secondary energy, such as BFG, BOFG, COG, electricity, and waste heat generated from the ironmaking and steelmaking processes, should be recycled and applied efficiently [15–16]. In this way, as EO increases, the CO2 emissions in steel works could be reduced. The utilization of these secondary energy outputs by other industrial or social users, instead of only consumption by the steel industry, is also encouraged as a type of industrial symbiosis practice that could reduce carbon emissions [53–54]. Thus, developing eco-industrial parks around ironmaking and steelmaking works is crucial to fully activate the energy transformation functions of the ironmaking–steelmaking process in terms of CO2 emission reduction [53].
To show the importance of the introduction of PGEF into the comprehensive management of CO2 emissions in steel works, the CO2 emissions and the PGEF of the specific sub-processes in the typical integrated process (plant A), including the processes of coking, sintering or pelletizing, BF ironmaking, BOF steelmaking, rolling, and the additional flux calcination to prepare flux (primarily in the form of lime) for the sintering and the BOF processes, during 2006–2009 were calculated as a case study. The results are shown in Table 1. The order of the processes from the highest to lowest CO2 emissions is BF, coking, sintering, rolling, BOF, flux calcination, and pellet processes. The CO2 emissions of the BF process account for the majority (averaged at 58.83%) of the total for plant A. The coking and sintering processes, following the BF process, account for 11.25% and 8.44% of the total emissions, respectively. Overall, the considered seven processes account for approximately 95% of the total emissions.
Process | CO2 emissions / Mt | Ratio of CO2 emissions to total / % | PGEF / (t∙GJ−1) | ||||||||||||||
2006 | 2007 | 2008 | 2009 | Average | 2006 | 2007 | 2008 | 2009 | Average | 2006 | 2007 | 2008 | 2009 | Average | |||
Coking | 1.76 | 1.72 | 1.65 | 1.39 | 1.63 | 11.8 | 11.0 | 11.0 | 10.7 | 11.2 | 0.16 | 0.18 | 0.18 | 0.2 | 0.18 | ||
Sintering | 1.10 | 1.24 | 1.33 | 1.09 | 1.19 | 7.4 | 7.9 | 8.9 | 8.4 | 8.1 | 0.10 | 0.10 | 0.10 | 0.09 | 0.09 | ||
Pellets | 0.50 | 0.48 | 0.42 | 0.11 | 0.38 | 3.4 | 3.1 | 2.8 | 0.9 | 2.6 | 0.14 | 0.14 | 0.14 | 0.13 | 0.15 | ||
BF | 8.11 | 9.08 | 9.03 | 8.64 | 8.72 | 54.3 | 58.1 | 60.4 | 66.8 | 59.7 | 0.10 | 0.1 | 0.11 | 0.11 | 0.11 | ||
BOF | 0.64 | 0.45 | 0.47 | 0.49 | 0.51 | 4.3 | 2.9 | 3.2 | 3.8 | 3.5 | 0.06 | 0.04 | 0.04 | 0.05 | 0.05 | ||
Rolling | 0.82 | 0.95 | 0.90 | 0.80 | 0.87 | 5.5 | 6.1 | 6.0 | 6.2 | 6.0 | 0.09 | 0.07 | 0.08 | 0.08 | 0.08 | ||
Flux calcination | 0.48 | 0.42 | 0.46 | 0.41 | 0.44 | 3.2 | 2.7 | 3.1 | 3.2 | 3.0 | 0.32 | 0.33 | 0.35 | 0.33 | 0.33 | ||
Others | 1.51 | 1.26 | 0.67 | 0.01 | 0.86 | 10.1 | 8.1 | 4.5 | 0.1 | 5.9 | |||||||
Total | 14.93 | 15.62 | 14.94 | 12.94 | 14.61 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.10 | 0.11 | 0.11 | 0.11 | 0.11 |
A systematic analysis of the CO2 emissions of each sub-process in the typical integrated process is shown in Fig. 6, with PGEFi, Yi, and Qi taken into consideration. From Eq. (12), the CO2 emission intensity of each process is the volume of a three-dimensional emission box, with Yi, PGEFi, and Qi as its length, width, and height, respectively. The consumed amounts of the coke, sintered ore, flux, and pig iron per ton of crude steel were selected based on the typical values for iron and steel works in China.
Lower CO2 emissions would depend on the reduction of PGEFi, Yi, and Qi. Obviously, BF, coking, and flux calcination processes are energy-intensive, with a high value of Qi. Thus, promoting energy utilization efficiency is critical for these processes. Except for the BOF steelmaking process, where Yi remains at unity, reducing Yi for other processes, including sintering, BF, coking, and flux calcination, is important. Such reduction can be achieved by reducing iron losses, such as reducing in-house scrap generation, reducing the iron content of slag or dust, and reducing coke consumption. The Yi of the BF process is lower than unity because scrap is also used as an alternative iron source in the BOF process. Increasing the ratio of scrap as the iron source in the BOF process can thus significantly reduce the CO2 emissions of the integrated process by reducing the Y of the BF process. As to the process with high PGEFi, such as flux calcination, coking, and BF processes, substitution with an energy type that has a lower carbon content or substituting with a new process that uses low-carbon energy is a greatly encouraging approach aside from energy conservation. The effect of PGEFi on each process will be discussed in detail. With the use of this method, options for reducing the CO2 emissions of the ironmaking and steelmaking processes can be comprehensively evaluated and compared.
In terms of the PGEF, the order from highest to lowest of the processes is flux calcination, coking, BOF, pellets, BF, sintering, and rolling; this order differs from that for CO2 emissions. Although the CO2 emission proportion of the flux calcination process is low (approximately 3.0% of the total CO2 emissions), the PGEF for this process is highest because of the CO2 emission sources, which include two parts: one from energy consumption to provide the heat required for calcination and the other from the decomposition of the limestone [55]. The second CO2 source of the flux calcination process has no relationship with the energy consumption and thus greatly increases the PGEF of the flux calcination process. Therefore, reducing CO2 emissions only through energy saving in the flux calcination process is insufficient; process optimization, such as changing the flux form used in the sintering and BOF processes and reducing the flux consumption, is a much more critical approach [56].
For the coking process, the CO2 emissions also include two parts: the CO2 emissions from fuel combustion in the combustion chamber and the coal carbonization in the carbonization chamber. The second part, which has little relation to energy consumption, results in a comparatively high PGEF of the coking process depending on the definition of PGEF. Therefore, reducing the CO2 emissions of the coking process should depend on PGEF reduction by increasing the coking efficiency, thereby the coal composition adjustment and tar recovery, other than energy conservation. In the BOF process, the CO2 emissions due to the consumption of the carbon contained in the pig iron are also classified as CO2 emissions without direct relation to the energy consumption. The energy consumption of the sintering process is approximately one-third higher than that of the pelleting process, which is why substituting the sintering process with the use of pellets is always encouraged from the energy conservation perspective. However, the PGEF of the pelleting process is approximately two-thirds higher than that of the sintering process because of the large amount of electricity consumed by the exhaust blower in the sintering process. Thus, the substitution of the sintering process with pellets could benefit the energy conservation and utilization of low-grade ores. However, this approach would not necessarily result in CO2 emission reduction. From the carbon reduction perspective, the sintering process also shows potential advantages if the indirect CO2 emissions of electricity generation decrease.
For the other processes, CO2 emissions have a strong relationship with energy consumption, and the energy savings will be sufficient in reducing CO2 emissions. Meanwhile, optimizing the energy structure by increasing the utilization of low-carbon content energy sources will be beneficial to carbon reduction by reducing the PGEF. For example, in the BF process, increasing the injection of coal instead of using a part of coke is useful in reducing CO2 emissions because of its lower CO2 emission factor. However, technology restrictions limit the further reduction potential of CO2 emissions if only within the framework of the integrated process. For the decarbonization of the iron and steel industry in China, more innovative strategies should be designed and explored beyond the ore-based integrated process, such as process substitution with alternative iron resources, e.g., steel scrap or DRI, and the use of novel reduction agents such as hydrogen or natural gas.
Aside from the ore-based integrated process, the PGEF of the non-BF processes, including EAF, DR, and SR, were investigated. Over the past 20 years, the share of crude steel produced from scrap and DRI has steadily increased worldwide. SRI is another potential iron resource for steelmaking. Presently, crude steel production based on pig iron from BF accounts for approximately two-thirds of all production, while the rest of crude steel produced from scrap and DRI account for approximately 34% and 4%, respectively [6]. For typical industrial DRI technology, such as the MIDREX and HYL III processes, iron ore is reduced by a gas mixture (syngas) of CO and H2 obtained from natural gas reforming [34]. Meanwhile, the COREX process is the only industrial technology that has been applied to produce SRI [57]. The scrap-based EAF process and non-blast-furnace ironmaking processes, including MIDREX [58] and COREX [59–60], were selected to analyze the influence of process substitution on the decarbonization of China’s iron and steel sector.
The calculation method for the CO2 emissions of the three alternative processes is similar to that of the integrated process. The CO2 emissions of the typical EAF process were calculated already by the authors [32]. The raw material of the EAF process was assumed to be steel scrap without molten pig iron. The electrode, which contains 90% of the carbon consumed per ton of crude steel, was set as 1.2 kg based on the data for advanced EAF technology or ULTIMATE EAF. The carbon content of crude steel produced by the EAF process was set as 0.1wt%. Consequently, the energy consumption, CO2 emission intensity, and PGEF of the EAF process were calculated as 1.22 GJ∙t−1, 2.93 × 10−4 t∙t−1, and 2.40 × 10−4 t∙GJ−1, respectively.
The CO2 emissions of the DR process are based on data from the typical MIDREX process in South Africa. On the basis of the average production data from 2004 to 2005, the energy consumption intensity and CO2 emission factors of the input reducing gas and output exhaust gas were calculated as 18.98 GJ∙t−1, 1.2 × 10−3 t∙m−3, and 8.4 × 10−4 t∙m−3, respectively [58]. The carbon content of the DRI product from MIDREX was set as 2.0wt% based on the average worldwide carbon content range. In the carbon input items, the carbon contents of the air and raw iron ore were set as zero, and the indirect CO2 emissions from electricity consumption were not included. Thus, the CO2 emissions per ton DRI were calculated as 0.87 t∙t−1, and the PGEF of this DR process was calculated as 0.046 t∙GJ−1.
The CO2 emissions of the SR process were based on data from the typical COREX process. Three types of COREX processes with different productivities had been attempted at an industrial operation scale since the first industrial pilot went into production in South Africa in 1989. Presently, only the C-2000 process is still in the works. The production data of the four COREX C-2000 processes in South Korea, South Africa, and India can be referred to in Wang et al. (2006) [61]. During the calculation, the rare carbon contents in the air and raw ore were set as zero. The average carbon content of the typical coal applied in the C-2000 process was calculated as 62.5%, with a calorific value of 30.96 MJ∙kg−1 [60]. The carbon content in the slag was set as zero, while the CO2 emission factors of the SRI and output exhaust gasses were calculated as 0.04 t∙t−1 and 7.27 t∙(104∙m3)−1, respectively [59]. Consequently, the energy consumption and the CO2 emissions per ton production of SRI by the COREX process were calculated as 15.67 GJ∙t−1 and 1.24 t∙t−1, and the PGEF of this SR process was calculated as 0.079 t∙GJ−1.
The comparison of the different processes is shown in Table 2. In the EAF process, steel scrap is used as the iron source instead of pig iron, DRI, or SRI. All the processes of making iron from raw iron ore, such as coking, sintering, and BF operation, are unnecessary. Compared with the BF process, the DR process emits much less CO2, whereas the SR process emits slightly more CO2. Our results agree well with the research results from previous literature [25]. They showed that 1.21 t∙t−1 is emitted per ton of SRI production and the SRI process contributes very little to CO2 emission reduction if it is only compared with the 1.22 t∙t−1 emissions of the BF process. However, the SR and DR processes do not use coke and sintered iron ore, and they could replace all the coking, sintering, and BF processes. Therefore, a carbon reduction potential still exists if the integrated process is improved by substituting the DR or SR process for the BF ironmaking system.
Process | Item | Production | Energy intensity / (GJ∙t−1) | CO2 emission intensity / (t∙t−1) | PGEF / (t∙GJ−1) |
Ironmaking process | DR | DRI | 18.98 | 0.87 | 0.046 |
SR | SRI | 15.67 | 1.24 | 0.079 | |
BF (Plant A) | Pig iron | 11.40 | 1.18 | 0.105 | |
Steelmaking process | EAF | Crude steel | 1.22 | 2.93 × 10−4 | 2.40 × 10−4 |
BOF (Plant A) | Crude steel | 1.38 | 0.062 | 0.047 |
Fig. 7 shows the matrix of the ironmaking and steelmaking processes considering the BF–BOF integrated process, scrap-based EAF process, DRI-based EAF process, and SRI-based BOF process. For comparison purposes, the pig iron produced from the BF and the SRI from the COREX process was assumed to be used for the BOF steelmaking process, while scrap and DRI from MIDREX were used for the EAF steelmaking process. The consumed amounts of coke, sintered ore, flux, pig iron or SRI, and scrap or DRI per ton of crude steel were selected based on the typical value for iron and steel works in China. During the calculation, the ratios of SRI and DRI to the crude steel were assumed to be the same as the ratio of pig iron to crude steel in the integrated process with a value of 0.92, while the other iron source was assumed to be steel scrap.
On the basis of the results of specific processes shown in Table 2, the CO2 emissions of the EAF process, DR–EAF process, and SR–BOF process shown in Fig. 7 were calculated using Eq. (12), and the results were compared with that of the integrated process (same as that in Fig. 6) in Fig. 8. Fig. 8(a) shows that the CO2 emission intensity per ton of crude steel in the integrated process is as high as 1.82 t∙t−1, while the CO2 emission intensity of the ironmaking–steelmaking process reaches its lowest level of 0.10 t∙t−1 with the use of the scrap-based EAF process. The DRI provides an alternative option for scrap substitution, and the CO2 emission intensity could be reduced to 0.97 t∙t−1 in the DR–EAF process. SRI production based on low-grade coal could be another choice for steelmaking. In this case, the CO2 emission intensity of ironmaking–steelmaking process by SR–BOF could be reduced to 1.31 t∙t−1, which is approximately 30% lower than that of the integrated process. For the total processes considered, the PGEF of the EAF process is the lowest, and the PGEF of both the SR–BOF and DR–EAF processes are lower than that of the integrated process.
The CO2 emissions of the integrated process, the scrap-based EAF process, the DR–EAF process, and the SR–BOF process based on the low-carbon analysis are shown in detail in Fig. 8(b). Compared with the integrated process, the lowest CO2 emission intensity of the EAF process is achieved by energy conservation and the PGEF reduction. The EAF process shortens the ironmaking–steelmaking process and omits the energy consumption for the coking, sintering, and BF ironmaking process. Meanwhile, the PGEF of the EAF process is reduced primarily because of the dominant proportion of low-carbon or carbon-free energy sources, such as electric power, in the entire energy structure instead of coke and coal in the integrated process. The SR–BOF process reduce the CO2 emissions mainly because of its slightly lower energy consumption compared with that of the integrated process, while the PGEFs are almost at the same level because coal is also used dominantly in the SR–BOF process. The CO2 emissions of the DR–EAF process are approximately half those in the integrated process. The dominant contribution is the lower PGEF of the DR–EAF process because of the utilization of natural gas, given the even higher energy intensity of the DR–EAF process.
Thus, promoting the non-BF ironmaking processes and the EAF process would play a significant role in the decarbonization strategy of the iron and steel industry through their comprehensive influence on the Yi, Qi, and PGEFi. The scrap-based EAF process is the best choice for the entire steelmaking industry from the viewpoint of CO2 emission reduction. The scrap-based EAF process can further reduce CO2 emissions released from the mining of iron ore or coal [62]. However, unlike in the conventional BF–BOF process, variable scrap supply in terms of quantity and quality and the lower quality of EAF steel are two important issues in the scrap-based EAF process. To increase the contribution of the scrap-based EAF process to the decarbonization of the Chinese iron and steel industry, two efforts should be enhanced: (1) promoting the scrap collection rate and sorting efficiency and (2) developing advanced refining technology to produce high-quality steel from scrap. The current scrap volumes are not sufficient to supply the entire steelmaking industry. In China, plenty of steel is still in use; however, the scrap amount will increase significantly in the near future, considering the experience of the US, Japan, and Europe. Comprehensive efforts are required to promote scrap-based EAF process development, such as the optimization of a lifetime evaluation system for steel production, enhancement of scrap recycling channels, the improvement of collection and sorting of new/old scrap, and the development of advanced EAF technology to treat complex scrap types [63].
Moreover, innovating alternative and novel ironmaking and steelmaking processes is critical for the decarbonization strategy [22,27]. For example, aside from COREX discussed above, another smelting reduction process called FINEX has been developed as an alternative BF process [27]. Unlike COREX, FINEX can directly use fine iron ore without agglomeration. Without the pelletizing, sintering, or agglomeration of iron ores, the resource utilization (Yi) is further improved; the reduction and the heat supply materials are CO and H2 mixture gas from coal gasification, instead of coal or coke, thereby improving the energy cleanliness (PGEFi) greatly compared with the BF process [22]. With the emergence of much more novel processes, electrorefining of molten iron [40] and hydrogen ironmaking and steelmaking [20,23,64–65] will usher in a new age for the iron and steel industry with low carbon emissions or zero carbon emissions. A constant supply of clean energy sources, such as electricity or hydrogen gas, is critical for such novel processes. The decarbonization potential and effects of these processes on the entire iron and steel industry can be systematically investigated and evaluated from the aspects of resource utilization efficiency, energy utilization efficiency, and energy cleanliness based on a systematic low-carbon analysis method, namely, the analysis of the emission box.
This study systematically discussed the decarbonization options for ironmaking and steelmaking processes in China from the aspects of energy utilization, resource utilization, and energy cleanliness by using a systematic low-carbon analysis method or emission box analysis. This low-carbon analysis method can be easily used to investigate the decarbonization options for other processes or industries with large energy-related CO2 emissions. The main conclusions are shown below.
(1) The CO2 emissions of the ironmaking and steelmaking processes depend on PGEFi (the energy cleanliness or energy structure), Yi (resource utilization efficiency), and Qi (energy utilization efficiency). To reduce the CO2 emissions of the ironmaking and steelmaking processes, technologies that not only promote energy conservation but also optimize energy structure and improve resource utilization efficiency should be developed.
(2) Within the framework of the integrated process, promoting energy conservation (Qi) is critical for the BF, coking, and flux calcination processes. Policies to promote scrap utilization and technologies to reduce iron losses, such as reducing in-house scrap generation and decreasing the iron content in slag or dust, are important for CO2 emission reduction by increasing the resource utilization efficiency (Yi). Meanwhile, substitution with energy that has a lower carbon content or a new process that uses low carbon energy is important for processes with high PGEFi, such as flux calcination, coking, and the BF.
(3) Process substitution is encouraged to further reduce CO2 emissions. The CO2 emission per ton of crude steel in the integrated process (1.82 t) can be reduced based on the process substitution by the scrap-based EAF process (0.10 t), DR-based EAF process (0.97 t), or SR-based BOF process (1.31 t) through the comprehensive influence on the PGEFi, Yi, and Qi. Compared with the integrated process, the lowest CO2 emission intensity of the EAF process is achieved by energy conservation and energy restructuring. The SR–BOF process benefits CO2 emissions mainly because of its slightly lower energy consumption. With regard to the DR–EAF process, the dominant contribution is the lower PGEF, while the energy intensity of the DR–EAF process is even higher.
(4) Currently, scrap-based EAF is the best choice for the entire steelmaking industry from the viewpoint of CO2 emission reduction. To promote the development of scrap-based EAF, comprehensive efforts for policymakers are required, such as the improvement of the collection and sorting of steel scrap and promoting EAF technology to treat steel scrap that has complicated compositions.
This research was financially supported by the State Key Laboratory of Advanced Metallurgy, China (Project Code: 41603006). Mr. Hongfu Li from JIGANG Group Co., Ltd., China is gratefully acknowledged for his helpful comments and discussion.
The authors declare no conflict of interest.
[1] |
H. Wang, X. Lu, Y. Deng, et al., China’s CO2 peak before 2030 implied from characteristics and growth of cities, Nat. Sustainability, 2(2019), No. 8, p. 748. doi: 10.1038/s41893-019-0339-6
|
[2] |
Z. Liu, D.B. Guan, S. Moore, H. Lee, J. Su, and Q. Zhang, Climate policy: Steps to China’s carbon peak, Nature, 522(2015), No. 7556, p. 279. doi: 10.1038/522279a
|
[3] |
D.B. Guan, Y.L. Shan, Z. Liu, and K.B. He, Performance assessment and outlook of China’s emission-trading scheme, Engineering, 2(2016), No. 4, p. 398. doi: 10.1016/J.ENG.2016.04.016
|
[4] |
K. Daehn, R. Basuhi, J. Gregory, M. Berlinger, V. Somjit, and E.A. Olivetti, Innovations to decarbonize materials industries, Nat. Rev. Mater., 7(2022), No. 4, p. 275. doi: 10.1038/s41578-021-00376-y
|
[5] |
D. Raabe, C.C. Tasan, and E.A. Olivetti, Strategies for improving the sustainability of structural metals, Nature, 575(2019), No. 7781, p. 64. doi: 10.1038/s41586-019-1702-5
|
[6] |
World Steel Association, Steel Statistical Yearbook 2021, Brussels, Belgium, 2021 [February 2, 2022]. http://www.worldsteel.org
|
[7] |
Z.C. Guo and Z.X. Fu, Current situation of energy consumption and measures taken for energy saving in the iron and steel industry in China, Energy, 35(2010), No. 11, p. 4356. doi: 10.1016/j.energy.2009.04.008
|
[8] |
W.Q. Wu, Y.J. Li, T.Y. Zhu, and W.J. Cao, CO2 emission in iron and steel making industry and its reduction prospect, Chin. J. Process Eng., 13(2013), p. 175.
|
[9] |
J.C. Brunke and M. Blesl, A plant-specific bottom-up approach for assessing the cost-effective energy conservation potential and its ability to compensate rising energy-related costs in the German iron and steel industry, Energy Policy, 67(2014), p. 431. doi: 10.1016/j.enpol.2013.12.024
|
[10] |
N. Karali, T.F. Xu, and J. Sathaye, Reducing energy consumption and CO2 emissions by energy efficiency measures and international trading: A bottom-up modeling for the U.S. iron and steel sector, Appl. Energy, 120(2014), p. 133. doi: 10.1016/j.apenergy.2014.01.055
|
[11] |
L. Price, J. Sinton, E. Worrell, D. Phylipsen, H. Xiulian, and L. Ji, Energy use and carbon dioxide emissions from steel production in China, Energy, 27(2002), No. 5, p. 429. doi: 10.1016/S0360-5442(01)00095-0
|
[12] |
S. Siitonen, M. Tuomaala, and P. Ahtila, Variables affecting energy efficiency and CO2 emissions in the steel industry, Energy Policy, 38(2010), No. 5, p. 2477. doi: 10.1016/j.enpol.2009.12.042
|
[13] |
K. Tanaka, A comparison study of EU and Japan methods to assess CO2 emission reduction and energy saving in the iron and steel industry, Energy Policy, 51(2012), p. 578. doi: 10.1016/j.enpol.2012.08.075
|
[14] |
X.L. Wang and B.Q. Lin, How to reduce CO2 emissions in China’s iron and steel industry, Renewable Sustainable Energy Rev., 57(2016), p. 1496. doi: 10.1016/j.rser.2015.12.131
|
[15] |
X.C. Zhao, H. Bai, X. Lu, Q. Shi, and J.H. Han, A MILP model concerning the optimisation of penalty factors for the short-term distribution of byproduct gases produced in the iron and steel making process, Appl. Energy, 148(2015), p. 142. doi: 10.1016/j.apenergy.2015.03.046
|
[16] |
X.C. Zhao, H. Bai, Q. Shi, X. Lu, and Z.H. Zhang, Optimal scheduling of a byproduct gas system in a steel plant considering time-of-use electricity pricing, Appl. Energy, 195(2017), p. 100. doi: 10.1016/j.apenergy.2017.03.037
|
[17] |
H.M. Na, J.C. Sun, Z.Y. Qiu, et al., A novel evaluation method for energy efficiency of process industry—A case study of typical iron and steel manufacturing process, Energy, 233(2021), art. No. 121081. doi: 10.1016/j.energy.2021.121081
|
[18] |
W.Q. Long, S.S. Wang, C.Y. Lu, et al., Quantitative assessment of energy conservation potential and environmental benefits of an iron and steel plant in China, J. Cleaner Prod., 273(2020), art. No. 123163. doi: 10.1016/j.jclepro.2020.123163
|
[19] |
J.L. Suer, M. Traverso, and F. Ahrenhold, Carbon footprint of scenarios towards climate-neutral steel according to ISO 14067, J. Cleaner Prod., 318(2021), art. No. 128588. doi: 10.1016/j.jclepro.2021.128588
|
[20] |
K.H. Ma, J.Y. Deng, G. Wang, Q. Zhou, and J. Xu, Utilization and impacts of hydrogen in the ironmaking processes: A review from lab-scale basics to industrial practices, Int. J. Hydrogen Energy, 46(2021), No. 52, p. 26646. doi: 10.1016/j.ijhydene.2021.05.095
|
[21] |
J.C. Sun, H.M. Na, T.Y. Yan, et al., A comprehensive assessment on material, exergy and emission networks for the integrated iron and steel industry, Energy, 235(2021), art. No. 121429. doi: 10.1016/j.energy.2021.121429
|
[22] |
X.Y. Zhang, K.X. Jiao, J.L. Zhang, and Z.Y. Guo, A review on low carbon emissions projects of steel industry in the World, J. Cleaner Prod., 306(2021), art. No. 127259. doi: 10.1016/j.jclepro.2021.127259
|
[23] |
J. Tang, M.S. Chu, F. Li, C. Feng, Z.G. Liu, and Y.S. Zhou, Development and progress on hydrogen metallurgy, Int. J. Miner. Metall. Mater., 27(2020), No. 6, p. 713. doi: 10.1007/s12613-020-2021-4
|
[24] |
M. Fischedick, J. Marzinkowski, P. Winzer, and M. Weigel, Techno-economic evaluation of innovative steel production technologies, J. Cleaner Prod., 84(2014), p. 563. doi: 10.1016/j.jclepro.2014.05.063
|
[25] |
C.Q. Hu, X.W. Han, Z.H. Li, and C.X. Zhang, Comparison of CO2 emission between COREX and blast furnace iron-making system, J. Environ. Sci., 21(2009), p. S116. doi: 10.1016/S1001-0742(09)60052-8
|
[26] |
M.A. Quader, S. Ahmed, R.A.R. Ghazilla, S. Ahmed, and M. Dahari, A comprehensive review on energy efficient CO2 breakthrough technologies for sustainable green iron and steel manufacturing, Renewable Sustainable Energy Rev., 50(2015), p. 594. doi: 10.1016/j.rser.2015.05.026
|
[27] |
A. Hasanbeigi, M. Arens, and L. Price, Alternative emerging ironmaking technologies for energy-efficiency and carbon dioxide emissions reduction: A technical review, Renewable Sustainable Energy Rev., 33(2014), p. 645. doi: 10.1016/j.rser.2014.02.031
|
[28] |
R. Zhu, B.C. Han, K. Dong, and G.S. Wei, A review of carbon dioxide disposal technology in the converter steelmaking process, Int. J. Miner. Metall. Mater., 27(2020), No. 11, p. 1421. doi: 10.1007/s12613-020-2065-5
|
[29] |
V. Strezov, A. Evans, and T. Evans, Defining sustainability indicators of iron and steel production, J. Cleaner Prod., 51(2013), p. 66. doi: 10.1016/j.jclepro.2013.01.016
|
[30] |
S.H. Zhang, E. Worrell, W. Crijns-Graus, F. Wagner, and J. Cofala, Co-benefits of energy efficiency improvement and air pollution abatement in the Chinese iron and steel industry, Energy, 78(2014), p. 333. doi: 10.1016/j.energy.2014.10.018
|
[31] |
T. Ariyama and M. Sato, Optimization of ironmaking process for reducing CO2 emissions in the integrated steel works, ISIJ Int., 46(2006), No. 12, p. 1736. doi: 10.2355/isijinternational.46.1736
|
[32] |
H. Bai, P. Liu, H.X. Li, L.H. Zhao, and D.Q. Cang, Analysis of carbon emission reduction of China’s integrated steelworks, [in] N.R. Neelameggham, C.K. Belt, M. Jolly, R.G. Reddy, and J.A. Yurko, eds., Energy Technology 2011: Carbon Dioxide and Other Greenhouse Gas Reduction Metallurgy and Waste Heat Recovery, John Wiley & Sons, Inc., Hoboken, 2011, p. 253.
|
[33] |
L.M. Germeshuizen and P.W.E. Blom, A techno-economic evaluation of the use of hydrogen in a steel production process, utilizing nuclear process heat, Int. J. Hydrogen Energy, 38(2013), No. 25, p. 10671. doi: 10.1016/j.ijhydene.2013.06.076
|
[34] |
A.R. da Costa, D. Wagner, and F. Patisson, Modelling a new, low CO2 emissions, hydrogen steelmaking process, J. Cleaner Prod., 46(2013), p. 27. doi: 10.1016/j.jclepro.2012.07.045
|
[35] |
M.T. Johansson, Bio-synthetic natural gas as fuel in steel industry reheating furnaces – A case study of economic performance and effects on global CO2 emissions, Energy, 57(2013), p. 699. doi: 10.1016/j.energy.2013.06.010
|
[36] |
D.B. Guo, L.D. Zhu, S. Guo, et al., Direct reduction of oxidized iron ore pellets using biomass syngas as the reducer, Fuel Process. Technol., 148(2016), p. 276. doi: 10.1016/j.fuproc.2016.03.009
|
[37] |
H. Helle, M. Helle, H. Saxén, and F. Pettersson, Mathematical optimization of ironmaking with biomass as auxiliary reductant in the blast furnace, ISIJ Int., 49(2009), No. 9, p. 1316. doi: 10.2355/isijinternational.49.1316
|
[38] |
P. Sodsai and P. Rachdawong, The Current situation on CO2 emissions from the steel industry in Thailand and mitigation options, Int. J. Greenhouse Gas Control, 6(2012), p. 48. doi: 10.1016/j.ijggc.2011.11.018
|
[39] |
H. Suopajärvi, E. Pongrácz, and T. Fabritius, Bioreducer use in Finnish blast furnace ironmaking – Analysis of CO2 emission reduction potential and mitigation cost, Appl. Energy, 124(2014), p. 82. doi: 10.1016/j.apenergy.2014.03.008
|
[40] |
W.D. Judge, J. Paeng, and G. Azimi, Electrorefining for direct decarburization of molten iron, Nat. Mater., 21(2022), 10, p. 1130. doi: 10.1038/s41563-021-01106-z
|
[41] |
M. Asanuma, T. Ariyama, M. Sato, et al., Development of waste plastics injection process in blast furnace, ISIJ Int., 40(2000), No. 3, p. 244. doi: 10.2355/isijinternational.40.244
|
[42] |
A. Ziębik and W. Stanek, Forecasting of the energy effects of injecting plastic wastes into the blast furnace in comparison with other auxiliary fuels, Energy, 26(2001), No. 12, p. 1159. doi: 10.1016/S0360-5442(01)00077-9
|
[43] |
M. Meng, D.X. Niu, and W. Shang, CO2 emissions and economic development: China’s 12th five-year plan, Energy Policy, 42(2012), p. 468. doi: 10.1016/j.enpol.2011.12.013
|
[44] |
R.G.D. Pinto, A.S. Szklo, and R. Rathmann, CO2 emissions mitigation strategy in the Brazilian iron and steel sector – From structural to intensity effects, Energy Policy, 114(2018), p. 380. doi: 10.1016/j.enpol.2017.11.040
|
[45] |
W.Y. Chen, X. Yin, and D. Ma, A bottom-up analysis of China’s iron and steel industrial energy consumption and CO2 emissions, Appl. Energy, 136(2014), p. 1174. doi: 10.1016/j.apenergy.2014.06.002
|
[46] |
A. Hasanbeigi, L. Price, C.X. Zhang, N. Aden, X.P. Li, and F.Q. Shangguan, Comparison of iron and steel production energy use and energy intensity in China and the U.S., J. Cleaner Prod., 65(2014), p. 108. doi: 10.1016/j.jclepro.2013.09.047
|
[47] |
A. Hasanbeigi, W. Morrow, J. Sathaye, E. Masanet, and T.F. Xu, A bottom-up model to estimate the energy efficiency improvement and CO2 emission reduction potentials in the Chinese iron and steel industry, Energy, 50(2013), p. 315. doi: 10.1016/j.energy.2012.10.062
|
[48] |
Y. Li and L. Zhu, Cost of energy saving and CO2 emissions reduction in China’s iron and steel sector, Appl. Energy, 130(2014), p. 603. doi: 10.1016/j.apenergy.2014.04.014
|
[49] |
E. Worrell, L. Price, and N. Martin, Energy efficiency and carbon dioxide emissions reduction opportunities in the US iron and steel sector, Energy, 26(2001), No. 5, p. 513. doi: 10.1016/S0360-5442(01)00017-2
|
[50] |
H. Bai, X. Lu, H.X. Li, et al., The relationship between energy consumption and CO2 Emissions in iron and steel making, [in] M.D. Salazar-Villalpando, N.R. Neelameggham, D.P. Guillen, S. Pati, and G.K. Krumdick, eds., Energy Technology 2012: Carbon Dioxide Management and Other Technologies, John Wiley & Sons, Inc., Hoboken, 2012, p. 125.
|
[51] |
X. Lu, H. Bai, L.H. Zhao, X.T. Liu, and D.Q. Cang, Relationship between energy consumption and CO2 emission of iron and steel plant, J. Univ. Sci. Technol. Beijing, 34(2012), p. 1445.
|
[52] |
R.L. Milford, S. Pauliuk, J.M. Allwood, and D.B. Müller, The roles of energy and material efficiency in meeting steel industry CO2 targets, Environ. Sci. Technol., 47(2013), No. 7, p. 3455. doi: 10.1021/es3031424
|
[53] |
B. Yu, X. Li, L. Shi, and Y. Qian, Quantifying CO2 emission reduction from industrial symbiosis in integrated steel Mills in China, J. Cleaner Prod., 103(2015), p. 801. doi: 10.1016/j.jclepro.2014.08.015
|
[54] |
H. Zhang, L. Dong, H.Q. Li, T. Fujita, S. Ohnishi, and Q. Tang, Analysis of low-carbon industrial symbiosis technology for carbon mitigation in a Chinese iron/steel industrial park: A case study with carbon flow analysis, Energy Policy, 61(2013), p. 1400. doi: 10.1016/j.enpol.2013.05.066
|
[55] |
Y.L. Shan, Z. Liu, and D.B. Guan, CO2 emissions from China’s lime industry, Appl. Energy, 166(2016), p. 245. doi: 10.1016/j.apenergy.2015.04.091
|
[56] |
H. Li, L.F. Guo, Z.Q. Li, W.C. Song, and Y.Q. Li, Research of low-carbon mode and on limestone addition instead of lime in the BOF steelmaking, J. Iron Steel Res. Int., 17(2010), Suppl.2, p. 23.
|
[57] |
A. Ziebik, K. Lampert, and M. Szega, Energy analysis of a blast-furnace system operating with the COREX process and CO2 removal, Energy, 33(2008), No. 2, p. 199. doi: 10.1016/j.energy.2007.09.003
|
[58] |
H. Xu, H. Qian, Y.S. Zhou, and Z.Y. Li, MIDREX shaft technology in COREX–DR combined process at SALDANHA steel, World Iron Steel, 10(2010), No. 2, p. 6.
|
[59] |
X.D. Jin, Choice of non-coking ironmaking process, Iron Steel, 33(1998), No. 4, p. 11.
|
[60] |
Z.H. Kuang, J.J. Lin, and X.Q. Li, Performance of Coal used in COREX Technological Process, Ironmaking, 27(2008), No. 4, p. 60.
|
[61] |
L. Wang, L.H. Chen, H.O. Lv, Development situation of COREX smelting reduction process, J. Shenyang Inst. Eng. Nat. Sci., 2(2006), p. 373.
|
[62] |
L.Y. Liu, H.G. Ji, X.F. Lü, et al., Mitigation of greenhouse gases released from mining activities: A review, Int. J. Miner. Metall. Mater., 28(2021), No. 4, p. 513. doi: 10.1007/s12613-020-2155-4
|
[63] |
S. Pauliuk, R.L. Milford, D.B. Müller, and J.M. Allwood, The steel scrap age, Environ. Sci. Technol., 47(2013), No. 7, p. 3448. doi: 10.1021/es303149z
|
[64] |
D. Kushnir, T. Hansen, V. Vogl, and M. Åhman, Adopting hydrogen direct reduction for the Swedish steel industry: A technological innovation system (TIS) study, J. Cleaner Prod., 242(2020), art. No. 118185. doi: 10.1016/j.jclepro.2019.118185
|
[65] |
V. Vogl, M. Åhman, and L.J. Nilsson, Assessment of hydrogen direct reduction for fossil-free steelmaking, J. Cleaner Prod., 203(2018), p. 736. doi: 10.1016/j.jclepro.2018.08.279
|
电解固态Bi2O3制备具有高CO2电还原活性及高甲酸选择性的纳米金属铋催化剂
Int. J. Miner. Metall. Mater., 2024, 31 (4) : 803-811
Xiaoyan Wang, Safeer Jan, Zhiyong Wang, Xianbo Jin. Solid Bi2O3-derived nanostructured metallic bismuth with high formate selectivity for the electrocatalytic reduction of CO2[J]. International Journal of Minerals, Metallurgy and Materials, 2024, 31(4): 803-811. doi: 10.1007/s12613-023-2770-y
Int. J. Miner. Metall. Mater., 2024, 31 (6) : 1208-1227
Chenguang Qian, Chunquan Li, Peng Huang, Jialin Liang, Xin Zhang, Jifa Wang, Jianbing Wang, Zhiming Sun. Research progress of CO2 capture and mineralization based on natural minerals[J]. International Journal of Minerals, Metallurgy and Materials, 2024, 31(6): 1208-1227. doi: 10.1007/s12613-023-2785-4
CO–CO2–N2气氛下硼镁铁矿钠化焙烧制备硼砂及磁铁精矿的工艺研究
Int. J. Miner. Metall. Mater., 2023, 30 (11) : 2169-2181
Jinxiang You, Jing Wang, Mingjun Rao, Xin Zhang, Jun Luo, Zhiwei Peng, Guanghui Li. An integrated and efficient process for borax preparation and magnetite recovery from soda-ash roasted ludwigite ore under CO–CO2–N2 atmosphere[J]. International Journal of Minerals, Metallurgy and Materials, 2023, 30(11): 2169-2181. doi: 10.1007/s12613-023-2643-4
Danny Ochoa-Correa, Paul Arévalo, Edisson Villa-Ávila, et al. Feasible Solutions for Low-Carbon Thermal Electricity Generation and Utilization in Oil-Rich Developing Countries: A Literature Review. Fire, 2024, 7(10): 344.doi: 10.3390/fire7100344 | |
Chenguang Qian, Chunquan Li, Peng Huang, et al. Research progress of CO2 capture and mineralization based on natural minerals. International Journal of Minerals, Metallurgy and Materials, 2024, 31(6): 1208.doi: 10.1007/s12613-023-2785-4 | |
Qi Zhang, Guanghui Chen, Yuemeng Zhu, et al. Effects of heating temperature and atmosphere on element distribution and microstructure in high-Mn/Al austenitic low-density steel. International Journal of Minerals, Metallurgy and Materials, 2024, 31(12): 2670.doi: 10.1007/s12613-024-2867-y | |
Process | CO2 emissions / Mt | Ratio of CO2 emissions to total / % | PGEF / (t∙GJ−1) | ||||||||||||||
2006 | 2007 | 2008 | 2009 | Average | 2006 | 2007 | 2008 | 2009 | Average | 2006 | 2007 | 2008 | 2009 | Average | |||
Coking | 1.76 | 1.72 | 1.65 | 1.39 | 1.63 | 11.8 | 11.0 | 11.0 | 10.7 | 11.2 | 0.16 | 0.18 | 0.18 | 0.2 | 0.18 | ||
Sintering | 1.10 | 1.24 | 1.33 | 1.09 | 1.19 | 7.4 | 7.9 | 8.9 | 8.4 | 8.1 | 0.10 | 0.10 | 0.10 | 0.09 | 0.09 | ||
Pellets | 0.50 | 0.48 | 0.42 | 0.11 | 0.38 | 3.4 | 3.1 | 2.8 | 0.9 | 2.6 | 0.14 | 0.14 | 0.14 | 0.13 | 0.15 | ||
BF | 8.11 | 9.08 | 9.03 | 8.64 | 8.72 | 54.3 | 58.1 | 60.4 | 66.8 | 59.7 | 0.10 | 0.1 | 0.11 | 0.11 | 0.11 | ||
BOF | 0.64 | 0.45 | 0.47 | 0.49 | 0.51 | 4.3 | 2.9 | 3.2 | 3.8 | 3.5 | 0.06 | 0.04 | 0.04 | 0.05 | 0.05 | ||
Rolling | 0.82 | 0.95 | 0.90 | 0.80 | 0.87 | 5.5 | 6.1 | 6.0 | 6.2 | 6.0 | 0.09 | 0.07 | 0.08 | 0.08 | 0.08 | ||
Flux calcination | 0.48 | 0.42 | 0.46 | 0.41 | 0.44 | 3.2 | 2.7 | 3.1 | 3.2 | 3.0 | 0.32 | 0.33 | 0.35 | 0.33 | 0.33 | ||
Others | 1.51 | 1.26 | 0.67 | 0.01 | 0.86 | 10.1 | 8.1 | 4.5 | 0.1 | 5.9 | |||||||
Total | 14.93 | 15.62 | 14.94 | 12.94 | 14.61 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.10 | 0.11 | 0.11 | 0.11 | 0.11 |
Process | Item | Production | Energy intensity / (GJ∙t−1) | CO2 emission intensity / (t∙t−1) | PGEF / (t∙GJ−1) |
Ironmaking process | DR | DRI | 18.98 | 0.87 | 0.046 |
SR | SRI | 15.67 | 1.24 | 0.079 | |
BF (Plant A) | Pig iron | 11.40 | 1.18 | 0.105 | |
Steelmaking process | EAF | Crude steel | 1.22 | 2.93 × 10−4 | 2.40 × 10−4 |
BOF (Plant A) | Crude steel | 1.38 | 0.062 | 0.047 |
Process | CO2 emissions / Mt | Ratio of CO2 emissions to total / % | PGEF / (t∙GJ−1) | ||||||||||||||
2006 | 2007 | 2008 | 2009 | Average | 2006 | 2007 | 2008 | 2009 | Average | 2006 | 2007 | 2008 | 2009 | Average | |||
Coking | 1.76 | 1.72 | 1.65 | 1.39 | 1.63 | 11.8 | 11.0 | 11.0 | 10.7 | 11.2 | 0.16 | 0.18 | 0.18 | 0.2 | 0.18 | ||
Sintering | 1.10 | 1.24 | 1.33 | 1.09 | 1.19 | 7.4 | 7.9 | 8.9 | 8.4 | 8.1 | 0.10 | 0.10 | 0.10 | 0.09 | 0.09 | ||
Pellets | 0.50 | 0.48 | 0.42 | 0.11 | 0.38 | 3.4 | 3.1 | 2.8 | 0.9 | 2.6 | 0.14 | 0.14 | 0.14 | 0.13 | 0.15 | ||
BF | 8.11 | 9.08 | 9.03 | 8.64 | 8.72 | 54.3 | 58.1 | 60.4 | 66.8 | 59.7 | 0.10 | 0.1 | 0.11 | 0.11 | 0.11 | ||
BOF | 0.64 | 0.45 | 0.47 | 0.49 | 0.51 | 4.3 | 2.9 | 3.2 | 3.8 | 3.5 | 0.06 | 0.04 | 0.04 | 0.05 | 0.05 | ||
Rolling | 0.82 | 0.95 | 0.90 | 0.80 | 0.87 | 5.5 | 6.1 | 6.0 | 6.2 | 6.0 | 0.09 | 0.07 | 0.08 | 0.08 | 0.08 | ||
Flux calcination | 0.48 | 0.42 | 0.46 | 0.41 | 0.44 | 3.2 | 2.7 | 3.1 | 3.2 | 3.0 | 0.32 | 0.33 | 0.35 | 0.33 | 0.33 | ||
Others | 1.51 | 1.26 | 0.67 | 0.01 | 0.86 | 10.1 | 8.1 | 4.5 | 0.1 | 5.9 | |||||||
Total | 14.93 | 15.62 | 14.94 | 12.94 | 14.61 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 0.10 | 0.11 | 0.11 | 0.11 | 0.11 |
Process | Item | Production | Energy intensity / (GJ∙t−1) | CO2 emission intensity / (t∙t−1) | PGEF / (t∙GJ−1) |
Ironmaking process | DR | DRI | 18.98 | 0.87 | 0.046 |
SR | SRI | 15.67 | 1.24 | 0.079 | |
BF (Plant A) | Pig iron | 11.40 | 1.18 | 0.105 | |
Steelmaking process | EAF | Crude steel | 1.22 | 2.93 × 10−4 | 2.40 × 10−4 |
BOF (Plant A) | Crude steel | 1.38 | 0.062 | 0.047 |