Reduction of NO_x emission based on optimizing the proportions of mill scale and coke breeze during sintering process

How to cost-effectively reduce NO_x emission of iron ore sintering process is a new challenge for iron and steel industry at present. The effects of proportion of mill scale and coke breeze on the NO_x emission, strength of sinter and sinter indexes were studied by combustion tests and sinter pot tests. Results showed that the fuel-N’s conversion rate decreased with increasing of the proportions of mill scale. Because NO was reduced to N₂ by Fe₃O₄, FeO and Fe in mill scale. The strength of sinter reached a highest value at 8.0 wt% mill scale due to the formation of low melting point minerals. Meanwhile, the fuel-N’s conversion rate slightly increased and total NO_x emission significantly decreased with the proportions of coke breeze increased. Because CO formation and contents of N element in sintered mixture decreased. However, the strength of sinter was also decreased since the decreasing of the melting minerals. In addition, results of sinter pot tests indicated that NO_x emission obviousely decreased and sinter indexes have good performances when the proportions of mill scale and coke breeze were 8.0 wt% and 3.70 wt% in sintered mixture.