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What are the main difficulties in blast furnace smelting of vanadium titanium magnetite?

Posted by: steel world 2023-11-01 Comments Off on What are the main difficulties in blast furnace smelting of vanadium titanium magnetite?

1. In terms of raw materials, the strength of vanadium-titanium sinter is generally lower than that of ordinary sinter. Its drum index is generally 81 to 82%, while the drum index of ordinary sinter can reach 83 to 85%. The drum index of vanadium-titanium sinter after cooling is 6 to 7% higher than before cooling, indicating that vanadium-titanium sinter is more brittle in the hot state and its strength is not as good as ordinary sinter. At the same time, the low-temperature reduction powdering rate of vanadium-titanium sinter is much higher than that of ordinary sinter, generally greater than 60%, and as high as 80-85%.
2. Characteristics of slag. The main component of slag smelted in blast furnaces comes from the gangue component brought in by the raw fuel. The smelting of ordinary ore forms a quaternary (CaO-MgO-SiO2-Al2O3) slag system; while the smelting of vanadium-titanium ore forms a quintuple (CaO-MgO-SiO2-Al2O3-TiO2) slag system. Compared with quaternary slag, the biggest characteristics of five-element slag are: increased slag melting temperature, formation of foamy slag, thickening of slag, and low slag desulfurization ability. Among them, the melting temperature of low-titanium slag is different from that of ordinary quaternary slag. The slag systems are similar, and the formation of foamed slag is more obvious in the smelting of high titanium type slag. The thickening of the slag is due to the progress of the reduction process in the blast furnace, and part of the TiO2 in the slag is reduced to form titanium carbon and nitrogen compounds. The melting point of TiC is 3140±90℃, and the melting point of TiN is 2950±50℃, which is much higher than the maximum temperature in the furnace. The desulfurization ability of high-titanium slag is much lower than that of ordinary blast furnace slag, with Ls only 5 to 9.
3. In terms of molten iron, the viscous contents of the vanadium-titanium molten iron contain oxides of vanadium and titanium, which have a very high melting point and are higher than the tapping temperature. They cannot be melted the next time the iron is tapped. The volume decreases rapidly, and the hot metal tank can only be used dozens of times, which seriously affects the normal use and turnover of the hot metal tank, and brings difficulties to the planning and arrangement of normal tapping of the blast furnace.

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