Changes in thermal performance of coke in blast furnace smelting process of Bayan Obo mine
WANG Yu1,2, FAN Ying-jie1, CHAI Yi-fan1, WANG Yi-ci1, LUO Guo-ping1, AN Sheng-li1
1. School of Materials and Metallurgy(School of Rare Earth), Inner Mongolia University of Science and Technology, Baotou 014010, Nei Mongol, China; 2. Ironmaking Plant, Baotou Steel Union Co., Ltd., Baotou 014010, Nei Mongol, China
Abstract：Metallurgical coke has become one of the necessary raw materials for modern blast furnace ironmaking technology. It is known as the "basic food" of the iron and steel industry, and has important strategic value and economic significance. With the advent of low-carbon era and the application of large-scale coal injection technology, the functions of coke have been gradually replaced. In order to ensure the air permeability and liquid permeability in the furnace, as the "louver" of blast furnace reflow belt, its role as the material column skeleton and channel is more prominent. Therefore, a deep understanding of thermal performance changes of coke in the smelting process of Bayan Obo mine is significantly important to guide its efficient smelting. The feed coke and tuyere coke were taken from No.4 blast furnace in Baotou Steel as the research object. X-ray diffractometer, thermogravimetric vertical furnace, scanning electron microscope, energy spectrometer and other analysis methods were used. The differences in the basic characteristics, main phases of ash, coke reaction index(CRI), coke strength after reaction (CSR), microscopic pore structure, and the content and distribution of alkali metals were compared and analyzed. Finally, the thermal performance of coke in the smelting process of Bayan Obo mine were obtained. The results show that the coke in the blast furnace undergoes a gasification reaction during descending process, ash content increases, volatile matter content decreases, and SiO2 content decreases significantly, but the content of basic oxides such as CaO, K2O, Na2O, and MgO increases. In the early stage of secondary heating, nitrogen adsorption occurs in the coke, and the quality does not decrease but increases. In the later stage, the coke undergoes carbon gasification reaction, and the quality decreases rapidly, reactivity of tuyere coke is improved, and strength after the reaction is reduced. There are honeycomb-like pores on the surface of tuyere coke, and distribution of pore is uneven. In particular, the coke matrix eroded by slag and iron has rough pore walls, and the pores appear to merge. Alkali metals are enriched in tuyere coke, the content of alkaline oxides is increased. The half-width of (002) diffraction peak corresponding to the tuyere coke graphite carbon is sharply reduced, flat peak disappears, and the peak shape is sharp. The crystal structure tends to be ordered, and the degree of graphitization increases.
王宇, 樊莹杰, 柴轶凡, 王艺慈, 罗果萍, 安胜利. 焦炭在白云鄂博矿高炉冶炼中的热态性能变化[J]. 钢铁, 2022, 57(8): 50-59.
WANG Yu, FAN Ying-jie, CHAI Yi-fan, WANG Yi-ci, LUO Guo-ping, AN Sheng-li. Changes in thermal performance of coke in blast furnace smelting process of Bayan Obo mine[J]. Iron and Steel, 2022, 57(8): 50-59.
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2022, Vol. 57 
