In response to the negative impact of high-aluminum iron ore smelting, Nippon Steel has made the following progress in the study of charge structure and slag group control:
(1) Improve the FeO content in the sintered ore. The FeO content of iron ore integrated into the furnace is about 8% to 10%, which is much higher than that of the industry. In particular, the FeO of the acid sinter is controlled at 12% to 14%. The content of FeO in the sinter is increased. Although the sintering temperature is increased and the fuel consumption of the blast furnace is increased, the low-temperature reduction pulverization rate of the sinter can be effectively controlled. Production practices show that for every 5% increase in RDI, the fuel ratio increases by 1% and production decreases by 1.5%. Therefore, the Nippon Steel blast furnace has considered the comprehensive indicators and achieved very good results.
(2) adjusting the slag magnesium oxide (MgO) content, the control slag MgO: Al2O3 = 0.65 ~ 0.80, three yuan alkalinity R3 = 1.50 + 0.05, four yuan alkalinity R4 = 0.95 + 0.05, a reasonable slag phase composition, Improve slag fluidity. At the same time, improve the desulfurization capacity of the slag.
(3) Improve the physical heat of molten iron. As the content of Al2O3 in the slag increases, the melting temperature of the slag rises remarkably, which is beneficial to the heat storage of the blast furnace hearth. The physical heat of the molten iron is guaranteed to be T=1500±20°C during operation to improve the fluidity of the slag iron.
(4) Properly increase the amount of smelting slag and control the Al2O3/SiO2 ratio of the sintered ore. To improve the content of Al2O3 in the sinter, consider increasing the SiO2 content and increasing the stability of the slag. General blast furnace smelting high alumina iron ore experience, control Al2O3 / SiO2 ratio of 0.1 ~ 0.35, to ensure the quality of sinter, as the Al2O3 / SiO2 ratio increases, Al2O3 content increases, the vitreous is easy to form vitreous, sinter strength linear decrease. In the blast furnace smelting of Nippon Steel, the Al2O3/SiO2 ratio of slag has been mentioned to 0.5-0.6, which can still meet the blast furnace operation and obtain better benefits.
(5) Exploring the appropriate process measures under different Al2O3 content slag, laying the foundation for low-cost smelting: ω(Al2O3)=15%～17%, controlling slag binary alkalinity 1.05～1.15, ternary alkalinity 1.50 The quaternary alkalinity is about 0.97, the MgO/Al2O3 ratio is 0.65~0.70, and the furnace temperature control ω[Si]<0.40% can ensure that the physical heat reaches above 1480 °C, and the smelting is smooth.
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