Hydrogen metallurgy process under the background of carbon neutrality may be popular

For a long time, the hydrogen metallurgy process has been concerned by the industry because of its low carbon and low energy consumption characteristics, and the exploration of the process in the industry has been hot. The existing research on hydrogen metallurgy technology is gradually moving in the direction of diversification: hydrogen-carbon monoxide mixture iron, pure hydrogen iron making and other technologies are gradually unlocked, which is of great significance for the smooth realization of China's carbon peak carbon neutral goal. In addition to the research of hydrogen metallurgy process, the main factor restricting the effective practice of the process - hydrogen source also ushered in a new development opportunity. Hydrogen production by electrolytic water will provide a strong driving force for the development of hydrogen production industry with the compression of production costs. We have reason to believe that under the background of carbon neutrality, China's hydrogen metallurgy process will achieve great development in a real sense.

Carbon neutrality goal: China's steel industry will face new challenges

The Chinese government's emphasis on environmental protection and its determination to achieve carbon neutrality by 2020 are once again confirmed. China will adopt more powerful policies and measures to achieve the peak of carbon dioxide emissions by 2030 and strive to achieve carbon neutrality by 2060.

According to the PBL Norwegian Environmental Assessment Agency, total greenhouse gas emissions in 2018 were about 55.6 billion tonnes of CO2 equivalent, an increase of 2%, with the top five carbon emitting countries accounting for 62% of all greenhouse gas emissions, followed by China (26%), the United States (13%), the EU27 (8%), India (7%) and Russia (5%). As a major carbon emitter, China's proposal of carbon neutrality this time is of great significance to the world's carbon emission control and global sustainable development.

Specific to the steel industry, China is the world's steel consumption country, steel manufacturing is also in the forefront of the world. The rising steel production capacity means that it will take some time for China to reach the peak of steel production capacity in the real sense, and it is conservatively estimated that China's steel production will still maintain a good momentum of development in the next ten years, which seems to be different from the above mentioned China to strive to reach the carbon peak before 2030. Therefore, whether the steel industry can achieve effective control of carbon dioxide emissions in the industry through technological innovation and industrial upgrading in the next period of time will directly affect the effective realization of China's carbon peak.

Since the beginning of this century, China's crude steel production has ushered in a rapid rise, and the carbon dioxide emissions of the steel industry have also shown an increasing trend year by year. According to statistics, China's current ton of steel carbon dioxide emissions of about 2 tons, compared with 2000, down 33.2%. Obviously, in the past 20 years, China's steel industry energy conservation and emission reduction work has made more remarkable achievements, but measured by this progress, the carbon peak of the steel industry by 2030 is still not guaranteed to be effectively achieved, which also means that, China's iron and steel industry must adopt more effective energy saving and emission reduction technologies and means, through smelting technology innovation to ensure that the entire industry's carbon emissions are effectively controlled.

Hydrogen metallurgy may provide a solution for carbon reduction in the steel industry

China's existing steelmaking technology mainly has two categories, namely long process and short process, in which the long process involves the use of a large number of carbon-containing raw materials, obviously, carbon dioxide emissions are inevitable; Due to the need for a large amount of electricity in the short process, in view of the fact that China still mainly relies on fire power generation, the large-scale use of electric furnaces will also indirectly cause a large amount of carbon emissions.

Based on this, the steel industry has generally shifted the focus of research from improving existing iron-making equipment to introducing clean raw materials. Among many new iron-making technologies, hydrogen iron-making technology has become the first choice for many new iron-making technologies because of its natural environmental friendliness, and its specific implementation methods and effects are widely favored by the industry.

In the existing hydrogen metallurgy technology in China, the development of hydrogen rich reduction blast furnace and gas base direct reduction shaft furnace is gradually recognized by the industry. The hydrogen-rich reduction blast furnace is involved in the iron-making process by injecting hydrogen, natural gas, coke oven gas and other hydrogen-containing media. Relevant experiments have shown that hydrogen-rich blast furnace reduction iron making can effectively promote the production of pig iron to a certain extent, but because this process is based on traditional blast furnaces, the skeleton effect of coke cannot be completely replaced, that is, there is a limit value of hydrogen injection, and the carbon emission reduction under this process is limited. It is generally believed that the carbon emission reduction range of hydrogen rich blast furnace reduction can reach 10%-20%. This does not seem to mean much to meet our 2030 carbon peak target.

In contrast, the gas-based direct reduction shaft furnace process plays an important role in controlling the input of carbon-containing raw materials from the source and the final output of carbon dioxide. A gas-based direct reduction shaft furnace converts iron ore to direct reduced iron (DRI) by using a mixture of hydrogen and carbon monoxide instead of carbon monoxide as a reducing agent, which is then fed into an electric furnace for further smelting. Obviously, because hydrogen is the main reducing agent, its final product, carbon dioxide emissions will be effectively controlled. Compared with the hydrogen rich reduction blast furnace, the carbon dioxide emission per ton of iron ore smelting using the gas base direct reduction shaft furnace process is reduced by more than 50%. Taking the existing traditional long process iron making technology as an example, carbon dioxide emissions per ton of steel have dropped from the existing nearly 2 tons to less than 1 ton, which undoubtedly brings new possibilities for China to achieve carbon peak and carbon neutrality goals.

In addition to the existing use of hydrogen-carbon monoxide mixture for iron ore smelting, the exploration of pure hydrogen iron making in the industry has also been actively promoted. This process will reduce CO2 emissions by 98% compared to the long process, once again creating new possibilities for cleaner production in the steel industry. Of course, under the existing conditions, due to the strong endothermic effect of hydrogen reduction, the gas volume of the full hydrogen shaft furnace will increase significantly, the reduction rate will also be affected, and the full hydrogen has high requirements for equipment and operation, etc., and the full hydrogen metallurgy technology can not be promoted and applied in a large area in a real sense.

In summary, under the background of carbon peaking and carbon neutrality, the gas-based direct reduction shaft furnace process will be the mainstream hydrogen metallurgy technology means in China in the short term, and the further maturity of the process will also be the main exploration direction of the industry.

Analysis of important factors restricting the development of hydrogen metallurgy process

Gas-based direct reduction shaft furnace process undoubtedly brings a new idea for carbon control and emission reduction in China, but there are many problems in front of us. In addition to the equipment line production of the process, operator training and other factors, the source of hydrogen has a direct impact on the actual promotion and application of this technology.

The existing hydrogen production process is mainly divided into three categories: hydrogen production from fossil energy, industrial by-product hydrogen, and hydrogen production from electrolytic water. Fossil energy hydrogen production mainly includes coal hydrogen production and natural gas hydrogen production, of which the former as a low cost hydrogen production technology in the domestic development is more mature, it is estimated that in the case of raw coal (carbon content of more than 80%) 600 yuan/ton, the production cost is 8.85 yuan /kg, of which the raw material cost accounts for only 15%-20%. Compared with the 70% raw material cost ratio of natural gas hydrogen production, the cost of coal hydrogen production technology is more controllable. However, because the process of coal to hydrogen will extend more carbon footprint, this feature is contrary to low-carbon goals such as energy conservation and emission reduction. In recent years, coke oven gas hydrogen production, light cracking hydrogen production, chlor-alkali by-product hydrogen production as the main industrial by-product technology has been developed. These three hydrogen production processes theoretically produce high purity hydrogen, but the key to restricting its development is whether its raw materials are in sufficient supply. In the existing relatively mature electrolytic cell technology, proton exchange membrane (PEM) and alkaline electrolytic cell (AE) although the technology is not a problem, but due to the high cost of electricity, it has not been widely used. According to market electricity price estimates, the cost of hydrogen production by electrolytic water is about 30-40 yuan /kg.

In the above three hydrogen production processes, the purity of the finished hydrogen obtained by electrolytic water hydrogen production can be as high as 99% in theory, compared with other ways, electrolytic water hydrogen production undoubtedly has an absolute advantage in the key indicator of hydrogen purity. Of course, with the existing power supply situation, it is obviously impossible to popularize electrolytic water hydrogen production in a large area, but considering the development of clean energy power generation in China, the future use of such as biological energy, nuclear energy as a source of electrolytic water hydrogen production power may bring more possibilities for the further development of the process.

Sum up

For a long time, China's hydrogen metallurgy process has not ushered in rapid development due to technical, cost and other factors. However, in the new situation of carbon neutrality, the development of hydrogen metallurgy process has once again gained new momentum. At the same time, with the maturity of the relevant hydrogen production process and the reduction of the cost of hydrogen production brought about by the development of the new energy industry, it will also provide a strong guarantee for the development of hydrogen metallurgy process in China.

China's iron and steel industry has never stopped the exploration and practice of hydrogen metallurgy process. As early as the 1970s, China began to design and build a gas-based shaft furnace for the treatment of vanadium titanium magnetite pellets. In the 1980s, Baosteel carried out the semi-industrial test research on the production of direct reduced iron by BL coal-to-gas process and shaft furnace. Entering the new century, Taihang built a coke oven gas-shaft furnace direct reduction project with an annual output of 300,000 tons DRI; More recently, Hesteel Group and Italy's tenova Group officially signed an agreement to build a demonstration hydrogen energy development and utilization project, including an annual output of 600,000 tons of ENERGIRON direct reduction plant, which is scheduled to be put into production by the end of 2021. It is believed that in the near future, China's hydrogen metallurgy process will continue to mature, and gradually become the main force of ore smelting, leading the updated trend of industrial cleaner production.