Reduction of NOx emission based on optimized proportions of mill scale and coke breeze in sintering process

Reducing NO x emission of iron ore sintering process in a cost effective manner is a challenge for the iron and steel industry at present. Effects of the proportion of mill scale and coke breeze on the NO x emission, strength of sinter, and sinter indexes were studied by combustion and sinter pot tests. Results showed that the peak value of NO concentration, total of NO emission, and fuel-N conversion rate gradually decreased as the proportions of the mill scale increased because NO was reduced to N 2 by Fe 3 O 4 , FeO, and Fe in the mill scale. The strength of sinter reached the highest value at 8.0wt% mill scale due to the formation of minerals with low melting point. The fuel-N conversion rate slightly fluctuated and total NO x emission significantly decreased with the decreased proportions of coke breeze because CO formation and content of N element in the sintered mixture decreased. However, the sinter strength also decreased due to the decrease in the amount of the melting minerals. Furthermore, results of the sinter pot tests indicated that NO x emission decreased. The sinter indexes performed well when the proportions of mill scale and coke breeze were 8.0wt% and 3.70wt% respectively in the sintered mixture.