At present, blast furnace-to-converter long process steelmaking still occupies a dominant position among steelmaking enterprises in my country. Generally speaking, the traditional blast furnace process requires 350 kg of coke and 150 kg of pulverized coal to produce 1 ton of pig iron. Due to the use of fossil energy, large amounts of carbon dioxide and carbon monoxide are emitted during the process of ironmaking and steelmaking. Therefore, low-carbon metallurgical technology is considered to be an important starting point for carbon emission reduction in the steel industry in the future.

At present, low-carbon metallurgical projects considered to be more promising include Japan’s COURSE50 plan, Sweden’s SSAB’s breakthrough hydrogen ironmaking technology (HYBRIT) project, the European ultra-low carbon dioxide emission steelmaking process ULCOS project, and the German Carbon2Chem project. Low-carbon ironmaking is the core, exploring the path of low-carbon ironmaking industrialization, and realizing energy saving, emission reduction, and efficient green development.

The COURSE50 project in Japan focuses on blast furnace carbon reduction, and has developed a hydrogen reduction ironmaking method that partially uses hydrogen instead of coke as a reducing agent. It is expected that the carbon reduction target achieved through the development and application of this technology is 10%. The small-scale experimental blast furnace built at Nippon Steel's Sumikin Junjin Plant in 2015 was used to carry out blast furnace gas upgrading hydrogen-rich coke and blast furnace tuyere injection tests, and then the furnace body disassembly study was conducted to confirm partial hydrogen reduction using hydrogen as a reducing agent The ironmaking method can make the carbon dioxide emission value close to the desired emission reduction target.

The European ULCOS project has studied the top gas circulation process (TGR-BF) in the low-carbon blast furnace ironmaking technology. The process has three main features: one is to use pure oxygen instead of traditional preheated air (ie full oxygen injection); the second is to separate, capture and store carbon dioxide; the third is to use recycled carbon monoxide as a reducing agent to reduce coke Usage amount. The test results show that the TGR-BF process has the characteristics of easy operation, good safety, high efficiency and strong stability. Among them, part of the top gas after carbon dioxide is heated to 1200 degrees Celsius, oxygen and pulverized coal are mixed and injected into the furnace through the hearth tuyere, and the top gas after carbon dioxide is heated to 900 degrees Celsius from the appropriate position of the furnace body. Injection has the best emission reduction effect and can reduce carbon dioxide emissions by 26%. It has been determined as the first choice for the next industrial-scale blast furnace test.

Based on the ULCOS project, the HYBRIT project will study the direct reduction process using hydrogen, which is produced using non-fossil energy. Hydrogen reacts with pellets to produce direct reduced iron (DRI), which is charged into an electric furnace with scrap steel, or made into hot briquette iron for storage or sale. The core of the HYBRIT project is to upgrade technology and reduce costs, so that hydrogen smelting steel is economically competitive with traditional coke iron smelting. Both coke and hydrogen can be used as reducing agents to remove impurities in iron ore. Carbon dioxide emissions in traditional steel smelting processes account for 90% of the industry. For example, if hydrogen is used to replace coke, hydrogen will react with oxygen in iron ore to generate water vapor, realizing zero carbon emissions.

Different from the above technologies to reduce carbon emissions, the Carbon2Chem project uses chemical raw materials contained in the exhaust gas of steel mills, such as carbon, nitrogen and hydrogen in the form of carbon monoxide and carbon dioxide, to produce synthetic gas containing carbon and hydrogen, and then It is used in the production of various primary chemical products such as ammonia, methanol, polymers and higher alcohols to replace the current fossil raw materials such as natural gas and coal. Therefore, Carbon2Chem can not only convert the carbon dioxide in the exhaust gas of steel mills, but also save the use of carbon resources in the production of such synthetic gas. In September 2018, ThyssenKrupp's Car-bon2Chem project successfully converted steel mill exhaust gas into synthetic fuel and produced the first batch of methanol. In January 2019, ThyssenKrupp successfully used steel mill exhaust gas to produce ammonia, which was the first time in the world. ThyssenKrupp announced that there are currently about 50 steel plants in the world that meet the conditions for the introduction of the Carbon2Chem project, and have begun to establish contacts with interested parties around the world to discuss the application of the technology to other carbon dioxide-intensive industries.

In addition, Chinese steel companies are also actively exploring low-carbon metallurgical technologies. For example, the HBIS Group and the Italian Tenova Group signed a memorandum of understanding (MOU), agreeing to carry out in-depth cooperation in hydrogen metallurgy technology, using the world’s most advanced hydrogen production and hydrogen reduction technology, and jointly developing and developing joint ventures with Jingcheng. Construct the world's first 1.2 million tons of hydrogen metallurgical demonstration project, which will be used in the transformation and upgrading project of HBIS Xuangang. Jinghua Risteel Holding Group Co., Ltd. and China Iron and Steel Research Institute Technology Group Co., Ltd. signed the "Agreement for Cooperation on Hydrogen Metallurgy and High-end Steel Manufacturing Project with an Annual Production of 500,000 Tons. The project aims at the new technology-equipment-variety-user application of hydrogen metallurgy, carries out systematic and full-chain innovative development, and builds the first (set) with China’s independent intellectual property rights through a modern industrial and metallurgical joint production cycle ) A production line with an annual output of 500,000 tons of hydrogen metallurgy and high-end steel. China Baowu, China National Nuclear Corporation and Tsinghua University have launched a joint study on how nuclear energy technology and metallurgical manufacturing technology can work together and the feasibility of innovative technology chain and industrial chain. Compared with the traditional iron coking process, the coal-based hydrogen metallurgical process has the characteristics of short process, fewer monitoring points, small scale of water circulation and water treatment facilities, fewer flue gas emissions and small quantities, and can reduce energy consumption by more than 50%.