Effects of circulated flue gas components on iron ore sintering

Abstract

Sulfur dioxide is one of the precursors of acid rain and desulfurization of the exhaust gases in iron ore sintering plants is essential. For the purpose of reducing SO2 emissions of iron ore sintering, flue gas circulation sintering (FGCS) process was employed to enrich SO2 content in off-gas in this work. Effects of simulated flue gas components involving O 2, CO, SO2 and H2O(g) content and temperature on iron ore sintering properties were investigated in a laboratory scale sinter pot. Experimental results show that, compared with the conventional sintering process, the sinter quality became obviously worse when the O2 content in inlet gas was less than 18%. The presence of CO in inlet gas improved the sintering properties, so did the sensible heat of the heated inlet gas. However, either an excessive SO2 content of more than 1 000 ppm or H2O content of more than 5% in inlet gas would be detrimental for sintering and results in the sulfur retention in finished sinter. Thus, in the practice of FGCS, it is necessary to add O2 content up to no less than 18%, and keep H2O content less than 5% in the circulated flue gas. Beside, FGCS process is capable of enriching SO2 in off-gas with a peak value of 2 006 ppm when the SO2 content of inlet gas was 500 ppm, while the maximum SO2 content was 1 256 ppm in the conventional sintering process. SO2 concentrated in off-gas is more readily to be captured by the current flue gas desulfurization (FGD) technologies. © 2012 ISIJ.