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.
史春雷, 程欢, 肖璐颖, 侯健, 韩艳伟, 孙章. 碱金属富集对焦炭微观结构的影响[J]. 中国冶金, 2023, 33(6): 21-32.
SHI Chunlei, CHENG Huan, XIAO Luying, HOU Jian, HAN Yanwei, SUN Zhang. Effect of alkali metal enrichment on microstructure of coke[J]. China Metallurgy, 2023, 33(6): 21-32.
CHENG H, LIANG Y H, GUO R, et al. Effects of solution loss degree, reaction temperature, and high temperature heating on the thermal properties of metallurgical cokes[J]. Fuel, 2021, 283: 118936.
GORNOSTAYEV S S, HEIKKINEN E P, HEINO J J. Behavior of alkali-bearing minerals in coking and blast furnace processes[J]. Steel Research International, 2016, 87(9):1144.
ZHONG J B, ZHANG J L, LI K J, et al. Catalytic behavior of potassium vapor on coke gasification reaction[J]. Steel Research International, 2017, 88(3): 88.
[8]
WANG G W, REN S, ZHANG J L, et al. Influence mechanism of alkali metals on CO2 gasification properties of metallurgical coke[J]. Chemical Engineering Journal, 2020,387:124093.
LI K J, ZHANG J L, BARATI M, et al. Influence of alkaline (Na, K) vapors on carbon and mineral behavior in blast furnace cokes[J]. Fuel, 2015, 145: 202.
TAYLOR H S, NEVILLE H A. Catalysis in the interaction of carbon with steam and with carbon dioxide[J]. Journal of the American Chemical Society, 1921, 43(9): 2055.
[13]
FOX D A, WHITE A H. Effect of sodium carbonate upon gasification of carbon and production of producer gas[J]. Industrial and Engineering Chemistry Research, 1931, 23(3):259.
[14]
LONG F J, SYKES K W. The catalysis of the carbon monoxide-steam reaction[J]. Mathematical Physics, 1952, 215:111.
[15]
FRANKE F H, MERAIKIB M. Die katalytische wirkung von alkalien auf die vergasungsreaktion des kohlenstoffs[J]. Carbon, 1970, 8(4): 423.
[16]
WIGMANS T, HOOGLAND A, TROMP P, et al. The influence of potassium carbonate on surface area development and reactivity during gasification of activated carbon by carbon dioxide[J]. Carbon, 1983, 21(1): 13.
ZHONG J, ZHANG J, LI K, et al. The influence of simultaneous adsorption of potassium and sodium vapours on coke structure and performance[J]. Ironmaking and Steelmaking, 2017, 44(1): 36.
[22]
CAI Y D, LIU D M, PAN Z J, et al. Pore structure and its impact on CH4 adsorption capacity and flow capability of bituminous and subbituminous coals from Northeast China[J]. Fuel, 2013, 103: 258.
[23]
WANG G H, JU Y W, YAN Z F, et al. Pore structure characteristics of coal-bearing shale using fluid invasion methods: A case study in the Huainan-Huaibei Coalfield in China[J]. Marine and Petroleum Geology, 2015, 62: 1.
RAJARAO R, MANSURI I, DHUNNA R, et al. Characterisation of gas evolution and char structural change during pyrolysis of waste CDs[J]. Journal of Analytical and Applied Pyrolysis, 2014, 105: 14.
[27]
SADEZKY A, MUCKENHUBER H, GROTHE H, et al. Raman microspectroscopy of soot and related carbonaceous materials: Spectral analysis and structural information[J]. Carbon, 2005, 43(8): 1731.
[28]
GONG X Z, GUO Z C, WANG Z. Variation of char structure during anthracite pyrolysis catalyzed by Fe2O3 and its influence on char combustion reactivity[J]. Energy and Fuels, 2009, 23(9): 4547.
2023, Vol. 33 
