Research On Behavior Of SO₂/NO_X/CO_X In The Process Of Flue Gas Circulation Sintering Of Iron Ores

Iron ores sintering flue gas includes many kinds of harmful gas and is characterized by considerable quantity, temperature fluctuations, high dust emission, emissions instability. These lead to giant investment of equipment and high operating costs of subsequent treatment processes for sintering flue gas. Flue gas circulation sintering process is one of the most effective technologies of recovering heat from flue gases and reducing the total flue gas emissions.This paper identifies behavior of SO2/NOX/COX and effects on sintering indexes in the process of flue gas circulation sintering of iron ores. Following main conclusions are obtained.Research on behavior of SO2in flue gas circulation sintering process indicates that:In the moisture condensation zone and sinter mixture zone, SO2is absorbed by moisture and humid slaked lime in sinter mixture; in the drying and preheating zone, a small part of SO2is absorbed by dry sinter mixture; in the hot zone, large amount of SO2is generated, while SO2in circulating flue gas is absorbed by new minerals and dissociative CaO of sinters under the cooling process; in sinter zone, part of SO2is absorbed by residual CaO in sinter under the condition of humid circulating flue gas, which results in increase of residual sulfur content in finished sinters.Research on behavior of NOX in flue gas circulation sintering process indicates that:NOX in flue gas mainly comes from Fuel NOX generated by the combustion of fuels; the decrease of O2content and the increase of CO content in circulating gas reduces the quantity of NOX emissions; the increase of NOX content makes the peak value of NOX flow rate increase significantly and reduces the quantity of NOX emissions; CO2affects on the quantity of NOX emissions. In all temperature range of sinter zone, NOX itself does not decompose and CO2, SO2have no evident effect on NOX content changes; CO can reduce NOX content and the range of600℃-800℃is the optimal temperature range of NO reduction by CO; oxidizing atmosphere of the sintering process is the key factor to restrict the reaction of NO reduction by CO. Sinter pot experiments of flue gas circulation indicate that:sinter production and quality indexes are deteriorated by the decrease of O2content and increase of SO2, CO2, water vapor content in circulating gas, but can be improved by the increase of CO content and the adoption of circulating hot gas. And emission rules of SO2/NOX/COX in flue gas are following:The decrease of O2content and increase of CO, CO2content in circulating gas make the peak value of SO2content in flue gas decrease obviously, while the increase of SO2and H2O content make the peak value of SO2content increase to achieve the effect of SO2enrichment. NOX content in flue gas is reduced significantly with the decrease of O2content and increase of CO content. Circulations of SO2, CO2, H2O and hot gas are not obvious to reduce NOX content. CO2and CO contents are decreased with the decrease of O2content, as well as circulations of CO, SO2, H2O and hot gas. Circulation of CO2makes CO2content increase and CO content decrease. Each ratio of combustion rises or falls. There are46figures,32tables and89references in...