Prospects for the Development Path of Blast Furnace Ironmaking Technology

 　　one

　　Fully achieve precision materials. Fine materials are not only a problem of high strength and grade of raw materials and fuels, but also include many aspects such as high-temperature metallurgical performance, stability of composition and performance, content of harmful elements, and uniform particle size.

　　two

　　Stabilize blast furnace operation, strive to improve gas utilization rate, increase air temperature, inject rich oxygen, and significantly reduce fuel ratio. At present, the ash content of top loaded coke produced from domestic coal is about 12.5%, S is about 0.7%, M40 is about 78%, CRI is about 28%, and CSR is 56%~60%. The most suitable furnace capacity is within the range of 1000-2000m3 for small and medium-sized blast furnaces. To build larger blast furnaces, necessary measures must be taken to improve the quality of coke. Especially considering that after injecting coal powder, it replaces some of the coke, increases the load, reduces the amount of coke in the material column, prolongs the residence time of coke in the furnace, and experiences greater deterioration. Using blast furnace gas to burn the furnace and provide an air temperature of 1280-1300 ℃ to replace coke with the heat brought by hot air is an important measure to achieve low-carbon and low-cost ironmaking.

　　For most blast furnaces in China at present, an oxygen enrichment rate of 3% to 5% is relatively suitable; If the oxygen price drops to 0.3 yuan/cubic meter, the oxygen enrichment rate of the blast furnace is expected to increase to around 10%. In coastal areas of China, areas with high and fluctuating humidity in the south, and areas with large temperature differences between day and night, air blowing dehumidification technology should be adopted. At present, it is recommended to promote the injection of mixed coal, maintain a coal ratio suitable for smelting conditions at 130 ± 20kg/t HM, and create conditions to gradually increase the injection rate to 150-170kg/t HM. At the same time, it can expand the coal injection resources of the blast furnace, and replace high-quality anthracite with rich semicarbon and improved coal resources in China. Hydrogen rich gas, such as coke oven gas, is also worth further research as a fuel for blast furnace injection.

　　three

　　Emphasize the safety, longevity, and environmental protection of blast furnaces. The main limiting factors of blast furnace longevity technology are erosion of carbon bricks in the hearth, as well as damage to the bosh, waist, and lower cooling walls of the furnace body. By solving these two major issues well, the goal of long blast furnace life can be basically achieved. Adjusting the internal state of the blast furnace by optimizing the operating system and promoting the formation of a stable protective layer on the hot surface of the furnace hearth carbon bricks is the key to extending the service life of the furnace hearth. According to production practice analysis and research, one of the main reasons for the damage of copper cooling staves is the large belly angle of the blast furnace, which makes it difficult to stabilize the slag skin and easy to fall off. Comparing the belly angle of blast furnaces in Europe and China, the belly angle of blast furnaces in Europe is generally between 72 ° to 74 °, while in China it is between 76 ° to 78 °, which is worthy of our careful study. In terms of environmental protection technology, the denitrification of sintering flue gas currently relies more on source reduction and process control. In the future, emphasis should be placed on the development of integrated deep purification technology with high environmental protection, strong process scalability, and integrated collaborative control of desulfurization, denitrification, and dioxin removal, replacing existing single component desulfurization technology, especially the research and development of low-temperature flue gas denitrification technology. In addition, priority should be given to developing technologies for deep water conservation, sulfur resource recovery, and comprehensive utilization of by-products.

　　four

　　Explore intelligent technology for blast furnaces. In the future, with the implementation of the Industry 4.0 plan led by intelligent manufacturing, the construction of a deep learning neural network blast furnace expert system through the Internet of Things, mobile internet, cloud computing platform, and big data, as well as the integrated application of various technologies, will greatly benefit the optimization of blast furnace technology and even the progress of ironmaking process technology throughout the entire cycle.

　　five

　　Pay attention to basic theoretical research and continuously develop new processes and technologies. China is a major steel country, but in the field of ironmaking and even the entire steel metallurgy, there is a lack of technology with independent intellectual property rights, often in a state of keeping up, which greatly restricts the competitiveness of China's steel industry. Therefore, we should be led by enterprises, leverage the technological advantages of universities and research institutes, and combine the practical experience of enterprises to jointly tackle key problems. It is recommended to prioritize the basic research of key ironmaking technologies such as high proportion pellet blast furnace smelting technology, improving coke quality and scientific evaluation technology, blast furnace expert system based on big data, and coordinated emission reduction of flue gas pollutants during sintering process, in order to effectively promote the improvement of China's ironmaking technology level.