Popular science | A detailed explanation of hydrogen metallurgy

In the past few days, Hesteel's world's first 1.2 million-ton hydrogen metallurgy demonstration project has achieved safe and smooth continuous production of green DRI products. At present, the metallization rate of DRI products has reached 94%, and the key indicators have fully met the qualified product standards. They can be used as high-end materials to manufacture high-quality clean raw materials, and are important raw materials to replace electric furnace scrap, especially high-quality scrap. This marks the complete success of the first phase of HBIS's hydrogen metallurgy demonstration project. This project is the first example of the application of hydrogen as an energy source for large-scale industrial production. An important milestone in the transformation.

With "carbon peaking and carbon neutrality" becoming the main theme of global industrial development, the steel industry, which ranks second in carbon emissions, needs to undergo in-depth reforms. Due to its huge emission reduction potential, hydrogen metallurgy has become the commanding height that leading steel companies are determined to win. Many domestic and foreign steel companies are vigorously deploying projects such as hydrogen energy metallurgy, green hydrogen preparation, and hydrogen energy supply. From "carbon metallurgy" to "hydrogen metallurgy", the iron and steel industry is expected to remove the hats of high carbon emissions, high pollution, and high energy consumption.

Reduction reaction with substitution of hydrogen for carbon

Hydrogen metallurgy uses hydrogen instead of carbon as a reducing agent and energy source for ironmaking. The reduction product is water, which can achieve zero carbon emissions (the basic reaction formula is Fe2O3+3H2=2Fe+3H2O, the reducing agent is hydrogen, and the products are iron and water) .

01

Blast Furnace Hydrogen Rich Reduction

That is, hydrogen-rich gases such as natural gas and coke oven gas are injected to participate in the ironmaking process. Relevant experiments have shown that hydrogen-enriched reduction ironmaking in blast furnaces can reduce carbon emissions to a certain extent by accelerating the reduction of charge, but because the process is based on traditional blast furnaces, the skeleton effect of coke cannot be completely replaced, and the amount of hydrogen injection has a limit value , it is generally believed that the carbon emission reduction rate of blast furnace hydrogen-rich reduction can reach 10%-20%, and the effect is not significant enough.

02

Gas-based direct reduction shaft furnace

That is, by using a mixture of hydrogen and carbon monoxide as a reducing agent, iron ore is converted into direct reduced iron, which is then put into an electric furnace for further smelting. The addition of hydrogen as a reducing agent effectively controls carbon emissions. Compared with the hydrogen-rich reduction blast furnace, the emission of carbon dioxide per ton can be reduced by more than 50%. This method is more suitable for hydrogen metallurgy.

The carbon reduction rate of blast furnace hydrogen enrichment is 10%-20%, and the effect is limited. The gas-based direct reduction shaft furnace process is a direct reduction technology that does not require coking, sintering, ironmaking, etc., and can control carbon emissions from the source. Compared with blast furnace hydrogen-rich reduction, the carbon reduction rate can reach more than 50%, and the emission reduction potential is relatively low. It is an effective way to rapidly expand the production of direct reduced iron. However, the gas-based shaft furnace has many problems such as strong heat absorption effect, increased H2 gas volume into the furnace, increased production cost, decreased H2 reduction rate, high product activity, and difficulty in passivation and transportation. Whether it is blast furnace ironmaking or gas-based shaft furnace direct reduction of iron, the use of hydrogen metallurgy has a significant carbon reduction effect.

Multinational release of hydrogen metallurgy technology roadmap

In recent years, the global iron and steel industry is actively carrying out the practice of hydrogen energy metallurgy. Steel companies in Europe, Japan, South Korea and other countries and regions have formulated low-carbon metallurgy technology roadmaps including hydrogen energy metallurgy, accelerated research and development, testing and application, and sought technological breakthroughs to achieve carbon neutrality.

At present, there are already some cases of hydrogen metallurgy technology in the world, such as the Swedish anhydride iron HYBRIT project, the Salzgitter SALCOS project, the VAI H2Future project, and the ThyssenKrupp Carbon2Chem project in Germany.

China has a long way to go to realize "green hydrogen metallurgy"

At present, some domestic iron and steel enterprises have released plans for hydrogen metallurgy, built demonstration projects and put them into operation, and achieved certain innovative breakthroughs. However, the demonstration projects are still in the stage of industrial testing, and there are still imperfect infrastructure, blank relevant standards, high costs, and safety issues. Hydrogen and other issues, and considering factors such as gas source, preparation, storage and transportation, and cost at this stage, most of the hydrogen used is still "grey hydrogen", and there is still a long way to go before realizing "green hydrogen metallurgy".

The main utilization methods of hydrogen metallurgy in China's iron and steel industry include: blast furnace hydrogen-rich smelting technology, hydrogen shaft furnace direct reduction technology, hydrogen-based smelting reduction ironmaking technology, etc. Judging from the application progress of Chinese iron and steel enterprises, hydrogen metallurgy technology can help significantly reduce carbon emissions, promote the utilization of carbon resources, promote the development of new green short-process processes, realize fossil-free smelting, and open up steel-chemical-hydrogen energy coupling to reduce carbon route. In addition, hydrogen energy has also achieved good results in energy conservation and environmental protection in the field of logistics and transportation of Chinese iron and steel enterprises.

If China wants to realize green hydrogen metallurgy, it needs to study key technologies in the fields of distributed green energy utilization, hydrogen production and storage, hydrogen metallurgy, and CO2 removal in the future, and form a new iron and steel metallurgical production process with hydrogen energy as the core.

The future of hydrogen metallurgy is not far away

The research on global hydrogen metallurgy projects is mainly divided into three steps: (1) before 2025, establish a pilot demonstration project to verify the feasibility of large-scale hydrogen metallurgy; (2) by 2030, use hydrogen from coke oven gas and other by-products for hydrogen metallurgy (3) By 2050, the replacement of gray hydrogen by green hydrogen will be realized, and industrial production of hydrogen metallurgy will be carried out.

At present, the cooperation between hydrogen energy and the steel industry is a win-win result: hydrogen metallurgy is conducive to energy conservation and emission reduction for steel companies and the completion of low-carbon transformation; steel companies provide more practical applications for hydrogen energy, enriching the downstream industrial chain of hydrogen energy . Hydrogen energy and the steel industry complement each other. Conducive to the development of new energy.

The application of hydrogen metallurgy in the iron and steel industry still faces a series of severe challenges, such as the economy of green hydrogen still needs to be improved, the lack of experience in technology application, the high cost of hydrogen energy storage and transportation, and the lack of downstream market demand for hydrogen-based direct reduced iron products.

For the future development and application of hydrogen metallurgy in the iron and steel industry, three suggestions are put forward:

One is system advancement. The utilization of hydrogen energy should be promoted from the whole industrial chain system such as hydrogen production, hydrogen storage, hydrogen transportation, and hydrogen use. In particular, the actual application scenarios of steel production should be coordinated, and the deep integration of "production, education, research and gold use" should be systematically promoted.

The second is to play a market-oriented mechanism. At this stage, the cost of hydrogen smelting process is still much higher than that of traditional production process. It is necessary to give full play to the role of market mechanism in technological innovation and other fields, and further optimize the allocation of resources such as finance and talents.

The third is to strengthen international cooperation. We should further focus on specific breakthrough links, strengthen international exchanges including concepts, scientific research, technologies, paths, and management methods, and promote in-depth international cooperation.

Yu Yong, Chairman of the World Steel Association, President of the World Steel Development Research Institute, Secretary of the Party Committee and Chairman of the Hegang Group, introduced that in the past 30 years, the global steel industry has improved energy efficiency and promoted the application of new processes and new technologies for recycling, and the comprehensive energy per ton of steel has increased. Consumption has been reduced by 50%. At present, the global steel industry accounts for about 8% of the world's energy consumption and 7% of the world's carbon emissions. Facing the future, the iron and steel industry is the best way to achieve low-carbon or even "zero-carbon" emissions, whether it is energy structure innovation, process structure innovation, or hydrogen energy application. In particular, the innovation and application of hydrogen metallurgy technology will bring about a revolutionary change in traditional iron and steel metallurgy technology, freeing iron and steel production from the absolute dependence on fossil energy and solving the problem of carbon emissions from the source.

Although limited by various factors such as the environment and cost, the iron and steel industry has not yet achieved "one hydrogen to the end", but the development of clean energy is the direction and mission, and the potential of "hydrogen metallurgy" is unlimited.