Influence of Lime Coating Coke on NOx Concentration in Sintering Process

Abstract

Decreasing NOx emission in sintering process is a key issue in steel industry. NOx emission in sintering process is decreased by coke combustion under high temperature. It has been investigated that coating layer of CaO–Fe₂O₃ composition on coke surface (CF coating method) is effective for decreasing NOx. It has been considered that CaO–Fe₂O₃ coating layer promotes high temperature combustion and functions as catalyst for reduction of nitrogen oxide.

In this study, CaO coating of coke (Lime coating coke: LCC) has been studied as simple technology for decreasing NOx. As the results, LCC has been effective like a CF coating method and it has been understood that CF melt formation on coke surface is important for decreasing NOx. About coating CaO ratio, 10% was preferable. And decrease in mixing time of LCC with iron ores (Post-mixing) was also effective. By LCC post-mixing, 17.6% NOx decreased and sinter productivity increased.