Effect of Heat Supply on the CO and NO Formation in the Sintering Process of Iron Ores

Abstract

Combustion of coke particles in the fixed bed with mixed small alumina balls was investigated. NO decreased and CO was actively formed with increasing the heat supply. When exothermic material was used instead of the alumina ball NO decreased remarkably.
According to the results of sintering pot tests, it was showed that the retardation effect for NO formation by increasing the heat supply with increasing the coke content in the raw mix and the fuel gas amount for ignition was smaller than that by using an ore containing less amount of combined water and an exothermic material. The NO conversion ratio in the former case was 0.07 and in the latter 0.24%/kcal/kg-raw mix. These values were almost similar to those obtained from the sintering machine operation investigated after these sintering tests.
As a result of investigations on NO reduction in the sintering bed, the degree of NO reduction with CO in the bulk gas and coke particles was indicated to be smaller than 5-15%. The main effect for retardation of NO formation by the heat supply was proved to depend on the increase of CO/O₂ around the burning coke particles.