Influence mechanism of zinc on the solution loss reaction of coke used in blast furnace

Abstract

The influence mechanism of zinc on the solution loss reaction of coke at high temperature was studied using the method of liquid phase adsorption. The microcrystalline structure, pore structure, micro morphology and optical texture of coke were analyzed by X-Ray diffraction (XRD), BET, scanning electron microscopy (SEM) and optical microscopy in present research. The results show that zinc can increase the coke reactivity index (CRI) and decrease the coke strength after reaction (CSR). Furthermore, the CRI is the highest, as well as the CSR is lowest and the coke structure is severely damaged when the enriched zinc content in coke reaches to 1.17%. The results of XRD and polarizing microscopy show that the zinc catalysis on the solution loss reaction of anisotropic texture with higher degree of graphitization is larger than that of the isotropic texture. Combined with BET and optical panorama, it can be reveals that zinc can promote the generation and combination of coke pores during its catalysis process on gasification reaction, resulting in the increase of specific surface area and volume of micropores, which in turn provides favorable conditions for the permeation of zinc vapor and the kinetics condition of gasification reaction, thereby the reaction is further intensified. Meanwhile, large connected pores and honeycomb cavern caused by catalysis reduce the coke strength greatly. A compound phase containing zinc was not found in the reacted Zn-enrich coke after careful inspection through SEM/EDS and XRD, which reveals that the catalysis is derived from zinc. The zinc catalysis on the solution loss reaction of coke is mainly attributed to accelerating the decomposition of the ketone group, promoting the formation of CO gas.