Enhancing low-oxygen combustion reactivity in sintering fuels using CaO-coated coke: Insights from quasi-particle TGA and sintering pot experiment

Abstract

High proportion flue gas recirculation reduces oxygen content, affecting sintering production. To address combustion inhibition under low oxygen conditions, this study examines the impact of quasi-particle structure on combustion characteristics in hypoxic environments. The combustion characteristics of one-dimensional quasi-particles were quantitatively analyzed using non-isothermal and isothermal thermogravimetric experiments. The reactivity index and reaction rate constant of CaO-coated coke increased by 26.6 % and 15 %, respectively, compared to pure coke under 15 % O₂ conditions. Subsequent studies have shown that CaO-coating increases the number of active sites and extends the diffusion path of combustion products, significantly enhancing the catalytic combustion effect. These findings were used to propose a CaO premixed low-oxygen sintering scheme. The effect of low-oxygen sintering of two-dimensional discrete fuels on production indexes was investigated by sintering pot experiments. Experimental results indicate that CaO premixing increases vertical sintering speed by 6.33 %, enhancing productivity by 5.45 %. Furthermore, the melting time of the surface layer is prolonged by 50 %, leading to a 12.6 % yield increase and a 1.9 % improvement in drum strength. This study confirms that CaO premixing meets production requirements at 15 % O₂, thus providing data basis for improvements in the sinter flue gas recirculation rate.