Study on sticking mechanism of pellets under low H2/CO conditions

Abstract

In order to examine the sticking behavior of the pellets in the gas-based reduction shaft furnace under low H2/CO conditions and determine its influencing factors, the sticking behavior of pellets under different temperatures and H2/CO ratios was studied by SEM, EDS and reduction kinetics. The results indicated that when the temperature is raised from 800 °C to 980 °C, the sticking index of pellets increased from 5% to 78.82%. Different H2/CO ratios under low H2/CO conditions caused a variance in the sticking index. The sticking index of pellets was 57.61% under H2/CO = 1.8. The sticking phase between the adjacent pellets is mainly metallic iron phase. The mechanism of the sticking during the reduction process was the growth of newly formed fibrous metallic iron between the adjacent pellets. Further, fibrous metallic irons were hooked together to gather and thicken until being metal iron phase agglomerates.