关键词: 被覆型, 准颗粒, 催化燃烧, 燃烧特性, 动力学

Abstract: Iron ore fines sintering, as the main atmospheric pollution source of blast furnace-converter long process steel production, is facing the pressure and challenge of ultra-low emission under the background of carbon peaking and carbon neutrality. Solid fuel exists in the sintering layer of iron ore fines in various forms, and the mass fraction of the coated quasi-particles (S-type) is as high as 70%. Therefore, the S-type quasi-particles were taken as the research object, the influence of adhesion fines composition on coke combustion were analyzed, and the dynamic rate control link was clarified, which provided a theoretical basis for improving combustion efficiency. The coke particles with 2~3 mm particle size were used as the core particles, and Al2O3, SiO2, CaO, MgO, Fe2O3 pure reagents and synthetic CaO-Fe2O3 (CF) were used to replace iron ore fines as adhesion fines. Then, S-type with different composition adhesion layers were prepared respectively. The non-isothermal combustion test and combustion characteristics were studied by thermogravimetric analysis. The most probable mechanism function of combustion reaction was solved by Coats-Redfern method, and the kinetic physical model was established for kinetic analysis. The results showed that the combustion characteristics of quasi-particles were significantly affected by the composition of adhesive layer. CaO, CF and Fe2O3 had strong catalytic combustion effect. The ignition point and combustion temperature of coke particles were significantly reduced, and the combustion efficiency and conversion rate were improved. The catalytic ability of MgO was weak, and the catalytic ability from high to low was CaO>CF>Fe2O3>MgO. The most probable mechanism function of S-type quasi-particles in the rapid combustion stage was R3, the spherically symmetric unreacted shrinking nuclear model of quasi-particle combustion was established and analyzed. In the rapid combustion stage, the carbon-oxygen interface reaction advanced to the core, and the interface reaction rate was smaller than the internal diffusion rate, which was the control link affecting the combustion rate of quasi-particles.

Key words: coated type, quasi-particles, catalytic combustion, combustion characteristics, kinetics