Research On Behaviors Of Circulating Flue Gases In The Layers Of Iron Ore Sintering

Flue gas circulation sintering as one of the methods of reducing the emissions of pollutants such as SOx, NOx and COx by process control. Influences of flue gas recirculation on the gases in the zone of sinters、combustion and preheating have been studied by subdividing the sintering process, which is be beneficial to revealing the reduction mechanism of SOx, NOx and COx in flue gas circulation sintering.Influences of flue gas recirculation on the gases in the zone of sinters were studied. Once the circulating gases enter into the zone of sinters, the SO2of the sintering gases would react with the free calcium oxide to generate CaSO4, which is very steady, so that the content of S in sinters would rise. When the temperature of sinter increases from600℃to1000℃, the curing rate of SO2in circulating gases would first rise then fall. While the temperature of sinter is900℃, the curing rate of SO2is the highest. The curing rate of SO2would decline and the free calcium oxide involving in the reaction would add, as the concentration of SO2in circulating gases increases. When the free calcium oxide in sinters was increased from1.0%to3.0%, the curing rate of SO2would be obviously increased.While the temperature of sinter increasing from500℃to900℃,the degradation rate of NOX raises at first, then decreases. The degradation rate of NOX would be six percent at700℃, which is maximized.Effects of flue gas recirculation on the gases in the zone of combustion were studied. If the initial content of O2was lowered, the duration time of combustion would be longer and the generation of NOX would be less. When the initial concentration of O2was decreased from19.0%to11.5%, the reduction rate of NOX would raises from5.05%to23.91%. The increased NOX reaction with HCN would promote NOX generating N2. While the initial concentration of NOX increasing from80ppm to320ppm, the reduction rate of NOX would raise from7.69%to22.50%.Improving the temperture of combustion would be benefit for the emission reduction of NOX.While the temperature of combustion increasing from800℃to1300℃, the reduction rate of NOX raises from0.78%to33.11%. Compared with Fe2O3, the catalytic reduction ability of Fe3O4can be stronger in the reaction between CO and NOx-Compared with hematite, the reduction rate of NOx is more apparent,while the sintering mixture is mainly magnetite.The effects of flue gas recirculation on the gases in the zone of preheating were studied. There are CaO and Ca(OH)2in the zone of preheating, which can be reacted with SO2to generated CaSO3or CaSO4. The reaction rate can be accelerated when the temperature goes up or the SO2content entering into the zone of preheating is enlarged.There are56figures,13tables and78references in this paper.