Insight into a novel technique to regulate the emission profile of hazardous PM2.5 during iron ore sintering process

•Emission profile of PM2.5 throughout sintering process was revealed.•Distribution area of materials high in hazards impacts PM2.5 emission is revealed.•A novel method based on separate granulation is developed to adjust PM2.5 emission. Iron ore sintering is an important emission source of PM2.5, the efficient control of which benefits green iron & steel manufacturing. The emission profile of PM2.5 and hazardous elements was investigated and the relationship between them was revealed, and then a novel method was developed to regulate PM2.5 emissions. Results showed that both PM2.5 and hazardous elements K, Na, Pb and Cl presented high-concentration emission at later sintering stages, during which hazardous elements were the main components of PM2.5. This phenomenon implied that the emission of PM2.5 throughout sintering process was accompanied by hazardous elements. Based on this property, a novel method based on regulating the removal and conversion area of hazards was developed to adjust PM2.5 emission profile, through controlling the distribution of special iron ores with higher contents of hazards in sintering bed. Distributing special iron ores in bottom sintering layer realized the high-concentration intensive emission of PM2.5 within a narrow area during the later sintering stages, where the emitted mass proportion of PM2.5 increased from 47.9% to 77.6%. The changed emission profile of PM2.5 make it possible to achieve the efficient and economic emission reduction as the part of flue gas needing deep purification was considerably decreased.