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 O2, 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.

Behavior of SO2 in the Process of Flue Gas Circulation Sintering (FGCS) for Iron Ores

“…The proportion of O2 content and water vapor was chosen according to a former research which suggested that sintering process carried out under these conditions possessed good sintering indexes. 19) The inlet gas was taken into sintering pot after heated by a vertical resistance furnace to appropriate temperature. The schematic diagram of sintering apparatus is shown in Fig.…”

“…In addition, during the FGCS process, SO2 content in the flue gases obviously increases, which exerts positive effect on the subsequent flue gas desulphurization. 19) However, there is lack of researches on behaviors of SO2 during this process. The purpose of this study is to reveal the behavior of SO2 in different zones of sintering bed for FGCS process and its effects on the production and quality to fin-ISIJ International, Vol.…”

Effect of CO and CO2 Content in Suction Gas on Sintering Process for Iron Ores

“…The author's group have been investigating on the flue gas circulating sintering from fundamental point of view: a simulation study was first carried out for systematic understanding the emission rule of O2, SO2, NOx and COx in the outlet flue gas by the FGCS process; 1) effect of circulating gas components (SO2, O2, CO, water vapor) on the sintering indexes were then examined, 2) and the SO2 behavior in different sintering zones (sinter zone, drying and preheating zone, moisture condensation zone and sinter mixture zone) was also found out. 3) Some of the previous works 2,4,5) showed the effect of suction gas components (O2, CO, humidity) only on the quality and property of the sinter ores, however, the underlying reasons for the changing rule of the sintering indexes were not determined.…”

“…3) Some of the previous works 2,4,5) showed the effect of suction gas components (O2, CO, humidity) only on the quality and property of the sinter ores, however, the underlying reasons for the changing rule of the sintering indexes were not determined. This note will add them several findings obtained thereafter to clarify the influence of CO and CO2 content in suction gas.…”

Crystalline Phase Quantitation of Sintered Ore with Powder X-ray Diffractometry with Rietveld Refinement

“…On the basis of these results, the sintering conditions for the three samples may be different. However, it is difficult to consider the difference in detail because the sintering conditions depend on many factors, including basicity, 7,8) reducing gas, 17,36,37) and impurities, 3,8) which affect the quality of the sintered ore.…”