十月特刊：钢铁行业的去碳化
Decarbonizing the steel industry
卷首语：钢铁行业的绿色发展
Steel underpins modern society but its production generates intensive carbon dioxide emissions. For its sustainable development, the steel industry requires technology and product upgrades, driven by innovation and cooperation.
评论：碳中和引导钢铁行业改革
The steel industry in China has an important role in reducing national and global carbon emissions, demanding integrated actions and efforts across policies, industry and science to achieve the goal of carbon neutrality.
Carbon neutrality orientates the reform of the steel industry
Climate change is a global issue facing all of humanity. The amount of greenhouse gases continues to soar as carbon dioxide is heavily emitted from various sectors in countries across the whole world, posing a serious threat to human health and the environment. In this context, countries across the world jointly strive to reduce greenhouse gas emissions in the form of a global agreement, aiming to achieve the objectives of carbon dioxide peaking and carbon neutrality, a state of net-zero carbon dioxide emissions. To comply with these targets, the socioeconomic, energy and industrial systems, as well as the consumption behaviour of individuals, would be dramatically reconstructed.
Climate change is a global issue facing all of humanity. The amount of greenhouse gases continues to soar as carbon dioxide is heavily emitted from various sectors in countries across the whole world, posing a serious threat to human health and the environment. In this context, countries across the world jointly strive to reduce greenhouse gas emissions in the form of a global agreement, aiming to achieve the objectives of carbon dioxide peaking and carbon neutrality, a state of net-zero carbon dioxide emissions. To comply with these targets, the socioeconomic, energy and industrial systems, as well as the consumption behaviour of individuals, would be dramatically reconstructed.
Recognized as a fundamental sector that provides indispensable raw materials, and with the production output continuing to increase (Fig. 1a), the steel industry has become one of the main battlefields to combat carbon emissions. In 2019, the carbon dioxide emissions of the global steel industry reached 3.64 billion tons, accounting for ~10% of the total global emissions. China is the world’s largest steel producer and consumer, with carbon emissions from its steel sector accounting for >50% of the global steel industry total (Fig. 1b) and >15% of domestic carbon emissions. This highlights the imperative significance of steel industry decarbonization in China, which should be facilitated through technological upgrading in steel production and industrial structure optimization supported by efficient policy implementation.
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Low-carbon steelmaking technological routes based on BF–BOF and EAF processes.
采访：创新筑建绿色
Gang Qian from CITIC Pacific Special Steel, one of the major steelmakers in China, talks to Nature Materials about their experience and perspective on moving towards decarbonization.
Innovation for green
Please tell us about your professional background and CITIC Pacific Special Steel.I obtained a PhD in metallurgy and have been engaged in technical research, product development, factory practice and business management in the area of iron and steel metallurgy for 34 years. I am currently Chairman at CITIC Pacific Special Steel and also serve as Vice President of the China Iron and Steel Association and President of the Special Steel Enterprises Association of China.
The steel industry is now facing the tough task of reducing carbon dioxide emissions, especially in China. As one of the largest steelmakers, what are your strategies to meet the target and requirement of decarbonization?As an international enterprise and a major supplier in this sector, it is our duty to strive for sustainable development and make our contribution to a cleaner world. To realize this goal, we have formulated a low-carbon sustainable development roadmap, committed to empowering ‘green manufacturing’ and contributing to ‘manufacturing green’. We started with the use of low-carbon technologies during the production process for green manufacturing. The development of advanced products that are high strength and lightweight and have a long life is also essential, to promote carbon reduction in the downstream industry and help end users to achieve green manufacturing. Moreover, with deepening cooperation in the industrial chain, we plan to develop more products to satisfy application needs in clean energy sectors to help manufacture green.... ...
研究论文：低氧稀土钢
The variation in the properties of rare earth (RE) steels is shown to stem from the presence of oxygen-based inclusions, and only under very-low-oxygen conditions can RE elements perform a vital role in purifying, modifying and micro-alloying steels.
Low-oxygen rare earth steels
Rare earth (RE) addition to steels to produce RE steels has been widely applied when aiming to improve steel properties. However, RE steels have exhibited extremely variable mechanical performances, which has become a bottleneck in the past few decades for their production, utilization and related study. Here in this work, we discovered that the property variation of RE steels stems from the presence of oxygen-based inclusions. We proposed a dual low-oxygen technology, and keeping low levels of oxygen content in steel melts and particularly in the raw RE materials, which have long been ignored, to achieve impressively stable and favourable RE effects. The fatigue life is greatly improved by only parts-per-million-level RE addition, with a 40-fold improvement for the tension–compression fatigue life and a 40% enhancement of the rolling contact fatigue life. We find that RE appears to act by lowering the carbon diffusion rate and by retarding ferrite nucleation at the austenite grain boundaries. Our study reveals that only under very low-oxygen conditions can RE perform a vital role in purifying, modifying and micro-alloying steels, to improve the performance of RE steels.
研究论文：基于电解精炼的熔铁直接脱碳方法
Application of electromotive force between molten iron–carbon and slag is shown to decarburize iron. Electrorefining decarburizes by direct interfacial electrochemical reaction, resulting in low solubilized oxygen in iron, even at low carbon concentration.
Electrorefining for direct decarburization of molten ironRecycling iron and steel is critical for environmental sustainability and essential to close material loops in circular economics. A major challenge is to produce high-value products and to control impurities like carbon in the face of stringent consumer requirements and volatile markets. Here, we develop an electrorefining process that directly decarburizes molten iron by imposing an electromotive force between it and a slag electrolyte. Upon anodic polarization, oxide anions from the slag discharge directly on carbon dissolved in molten iron, evolving gaseous carbon monoxide. In a striking departure from conventional practice that highly relies on reaction with solubilized oxygen, here electrorefining achieves decarburization by direct interfacial reaction. We demonstrate that this technique produces ultra-low-carbon steels and recovers silicon as a by-product at the cathode, requiring a low energy input and no reagents. We expect this process to be scalable and integrable with secondary steel mills.
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