Comparative investigation on the reduction behavior of blast furnace dust particles during in-flight process in hydrogen-rich and carbon monoxide atmospheres

Blast furnace (BF) dust is a typical fine-grained solid waste generated as by-product during the ironmaking process. A novel in-flight reduction technology has been developed to recovery the fine iron-bearing dusts efficiently and cleanly to bypass the sintering/pelletization steps. In this work, the reduction behavior of BF dust particle during in-flight process in H2-rich and CO atmosphere were investigated comparatively. A maximum reduction degree of 93.4% is obtained in H2-rich atmosphere at temperature of 1573 K within 1.6 s of reduction time. Morphological observations reveal that dust particles reduced in H2-rich atmosphere is more coarse and porous than in CO. The carbon contained in dust is confirmed to participate in the reduction process in the form of gasification. The heat and mass transfer characteristics between dust particle and reducing gas during in-flight process are also analyzed, which provide fundamental knowledge for effective utilization of BF dust with in-flight reduction technology. [Display omitted] •H2-rich in-flight reduction is an efficient iron-bearing dust recycling technology.•A maximum reduction degree of 93.4% of BF dust is achieved during in-flight process.•Morphology and microstructure evolutions of reduced BF dust particle are revealed.•Heat and mass transfer characteristic between particle and reducing gas is analyzed.