The ‘New Sintering High-temperature Flue Gas Circulation Technology of the Shougang Group’ jointly developed by the Shougang Research Institute of Technology, Beijing Shougang Co., Ltd. and University of Science and Technology Beijing recently passed its results evaluation and acceptance of the Chinese Society for Metals. The project not only creates annual direct economic benefits of more than RMB 20 million, but is also significant for the quality improvement, energy consumption reduction and emissions reduction of sintered ore. The project has been evaluated by experts to reach the international advanced level.

The energy consumption of the iron and steel industry accounts for about 15% of the total energy consumption of China's national economy, and the energy consumption of blast furnace ironmaking accounts for more than 70% of the energy consumption of the iron and steel industry. Blast furnace ironmaking is known to be based on ‘70% raw materials and 30% operation’. Beneficiated burden material is the basis of blast furnace ironmaking. Currenly, about 70% of China's blast furnace charge structure is sintered ore. As such, enhancing the quality of sintered ore is the top priority of the energy-saving and emissions reduction work in China's iron and steel industry. In addition, the sintering process is also an important source of energy consumption and pollution in the iron and steel industry, with the energy consumption of the process accounting for about 12% of the total energy consumption of the iron and steel industry, and the sintering flue gas emissions accounting for about 40% of the total flue gas produced by the industry.

For energy conservation, Europe has developed EOS, eposint, LEEP and other flue gas circulation sintering technologies. However, they are all applied in small sintering machines, and a high proportion of pellets are fed into the furnaces in Europe. Therefore, the sintering process focuses more on processing solid waste and charge mixture, without high requirements for sintered ore quality. The current situation in China is different, with sintered ore making up 60%-70% of the main raw material fed into the furnace, so such technologies are not suitable for direct introduction and application in China. To achieve quality improvement, energy conservation and emissions reduction, the sintering process faces such major problems as the lack of a relevant basic theory, lack of a design system and core equipment gaps, which seriously restrict the progress and development of sintering technology.

Since 2011, through more than five years of industry-university-research cooperation, the ‘New Sintering High-temperature Flue Gas Circulation Technology of the Shougang Group’ has overcome a series of major technical difficulties such as the technological theory of flue gas circulation in the sintering process, flue gas circulation system design and core equipment and technologies, and formed a set of key technologies for sintering quality improvement, energy conservation and emissions reduction. Through production tracking, research and improvement, it has gone through the test of production practice and made a major breakthrough in sintering technology. After the project was put into use, good effects were achieved: the average particle size of sintered ore has increased by 12%; the comprehensive return rate of sintering has decreased by 6.6%; the solid fuel consumption of sintering has been reduced by 3.39 kg/t; the blast furnace gas utilization rate has increased by 1%; blast furnace fuel consumption has been reduced by 2.7 kg/t; sintered dust emissions have been reduced by 27.81%; SO₂ emissions have been reduced by 15.89%; and NO_x emissions have been reduced by 23.41%. The annual direct economic benefits exceed RMB 20 million.

According to industry experts, there are currently more than 1,000 sintering machines in China, with sintered ore productivity of 900 million tons. The promotion of this project is significant for sintering quality improvement, consumption reduction and emissions reduction.