Effect of alkali metal enrichment on microstructure of coke
SHI Chunlei1, CHENG Huan1, XIAO Luying2, HOU Jian3, HAN Yanwei1, SUN Zhang1
1. College of Chemical Engineering, North China University of Science and Technology, Tangshan 063210, Hebei, China; 2. College of Science, North China University of Science and Technology, Tangshan 063210, Hebei, China; 3. Manufacturing Department of Hansteel, HBIS Group Co., Ltd., Handan 056009, Hebei, China
Abstract:Alkali metals are cyclically enriched in blast furnace, and the erosion of coke microstructure is one of the important factors leading to decrease of coke strength. In order to comprehensively elucidate the effect of alkali metal enrichment on the microstructure of coke, the adsorption experiments of pure K, pure Na and K-Na combined with 5% alkali vapor content were carried out on Coke A using monolayer evaporation alkali method. The microstructure of coke samples before and after alkali metal enrichment was characterized by combination of various means. The results show that, under the same amount of alkali vapor, the adsorption capacity of Na by Coke A is higher than that of K. K enrichment has obvious destructive effect on the macroscopic morphology of coke, and the SEM images show that K enrichment produces pore expansion and obvious cracks in the organization. The concentration of alkali metal enrichment decreases from outside to inside, and the erosion effect is gradually weakened. Alkali metal enrichment has obvious effect on the pore expansion of micron pores, while K and Na have the opposite effect on nanopores. Alkali metal enrichment significantly reduces the content of coarse mosaic texture, which may be an important factor leading to the reduction of coke macroscopic properties. K has greater impact on coke macrostructure, which may be related to its greater destruction on microcrystalline structure. This study lays an important foundation for in-depth understanding of the erosion effect of alkali metal enrichment on coke microstructure.
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