Formation of Nitrogen Mono Oxide (NO) during Iron Ore Sintering Process

Abstract

The effects of mineral phases evolution and atmosphere transition on the transformation of fuel-N during sintering process were studied in this paper. With the temperature increasing, the conversion rate of fuel-N to NO decreased as the coke was burning in the granules, due to the effect of sintering materials. This presented the contrary law compared with the fuel burning alone. As coke burnt at temperature below 1000°C, it was mainly the oxidizing reaction between fuel-N and oxygen. Iron ores and fluxes getting in touch with coke could promote the oxidation of fuel-N that converts to NO. While the temperature increased to higher than 1000°C, the gasification reaction between carbon and CO₂ occurred apparently and generated CO. There was a competition between fuel-N’s oxidation and NO’s reduction. Meanwhile, iron oxide and calcium ferrite (CF) had a catalytic effect on NO–CO reduction reaction. Particularly, the CF generated at high temperature had the most significant catalytic activity. As a consequence, the transformation of fuel-N was inhibited, making NO emission less at higher temperature.