Mechanism study on gas-based reduction swelling behavior of ultra-high grade pellets

作者：Jie Lei, Chen Zhang, Jingshu An, Yu-qi Kong, Shengping He, Hongming Long, Ting Wu · 发表于：Journal of Materials Research and Technology · 年份：2023 · DOI：10.1016/j.jmrt.2023.07.183 · 被引用次数：20 · 研究领域：Iron and Steelmaking Processes、Metal Extraction and Bioleaching、Mineral Processing and Grinding

Utilizing super-concentrate for direct hydrogen reduction in pelletizing which decrease energy consumption and improve smelting quality are critical steps towards achieving the dual carbon goal. The reduction swelling behavior and its corresponding mechanism of ultra-high-grade pellets were studied from multi-dimensions combing visualization detection, micromorphological analysis, and first-principles molecular dynamics simulation in present work. The results showed that for the reduction no matter in CO or H2 atmosphere, the ultra-high grade pellets expand abnormally. Whereas the increase of SiO2 content and the selection of H2 atmosphere can effectively inhibited the reduction swelling behavior of pellets, while Al2O3 content had only a slight effect. The cause of catastrophic expansion was related to the various formation of new-born iron that it exhibited angular during CO reduction while became flatter with SiO2 addition or by H2 reduction. The simulation results were validated the accuracy since the structure and energy changes during iron oxide reduction were corresponding to the experimental observations. C and Fe mainly formed chemical bonds while H and Fe primary produced physical adsorption during FexO reduction. Combing the comprehensive effect of adsorption energy, electrostatic force, and energy change, it was tended to create iron whiskers by CO reduction contrary to H2 reduction. It was conductive to generate iron whisker after Si doped in FexO. However, the d...