Effects of Adding Calcined Dolomite and Mill Scale to Sinter Mix on the Formation of NO and SO2 in Iron Ore Sintering Process

NO and SO 2 are representative harmful gases generated in steel works, and iron ore sintering process accounts for more than 50 pct of total generation. The current study investigated the effects of adding CaO and FeO, which are the components contained in raw materials to sinter mix on the formation of NO and SO 2 . The addition of CaO to sinter mix promoted the formation of NO due to the catalytic effect of CaO. It also increased the conversion ratio of sulfur to SO 2 by forming CaSO 4 which then released SO 2 as of 1200 °C. The addition of 5 wt pct of FeO significantly reduced the formation of NO and SO 2 , which could be believed that FeO reduced NO and SO 2 by converting them to N 2 and FeS, respectively. As the sources of CaO and FeO, calcined dolomite and mill scale with high potential for use in the steel industry were added to sinter mix to clarify their effects on the formation of NO and SO 2 . The addition of calcined dolomite increased the formation of NO more significantly due to the pores created by calcination and by the catalytic effects of CaO and MgO contained in calcined dolomite. The MgO in calcined dolomite also reacted with SO 2 to form MgSO 4 which was then thermally decomposed to release SO 2 from 1000 °C. The added mill scale increased the formation of NO and SO 2 , which could be believed that the catalytic effect of Fe 2 O 3 and Fe 3 O 4 in mill scale on the formation of NO and SO 2 might be more significant than the inhibiting effect of FeO on their formation.