Contribution Oral Presentation
A study on the coal-based direct reduction of high-grade magnetite concentrate pellets
The short process of electric furnace steelmaking with the burden of direct reduced iron (DRI), is an important process to produce high-quality and special steel, which is characteristic of low energy consumption. Meanwhile, coal-based rotary kiln is one of the most competitive processes for DRI production. In this paper, the high-grade magnetite concentrates with an iron grade of up to 68% is used as the iron-containing raw material to prepare the DRI by the coal-based rotary kiln direct reduction process. The results show that under the optimum conditions of the reduction temperature of 1100 ℃ for 120 min with C/Fe mass ratio of 1.5, the metallization rate and iron grade could reach 98.64% and 94.12%, respectively. The metallized pellets obtained from the best conditions have many advantages, such as high iron grade, few impurities, high added value and a wide range of applications, which could be used in the special steel smelting. However, there are also exist several disadvantages, including low compressive strength and high pulverization, resulting in rotary kiln accretion. In view of these problems, this study proposes many measures to improve the pellet strength and avoid the pulverization in the reduction process, which contains oxidation-roasting to improve the strength of oxidized pellets, stepwise reduction and stepwise coal addition.