Research On Behavior Of Alkali Metals In The Blast Furnace

With the development of iron and steel industry and the advancement of blast furnace smelting technology, the harmful defects of alkali metals in the blast furnace has been concerned more and more. Through the theoretical analysis on the behavior of alkali metals in the blast furnace, the author finds that alkali metals are introduced in the blast furnace chiefly from the iron ore and the coke, and are discharged mainly from slag. If the alkali metals in the blast furnace are not discharged effectively, the residual alkali metals must be circulated and accumulated constantly in the blast furnace. Alkali metals have a adversely influence on the blast furnace: increase coke consumption and decrease coke granularity and strength; increase mid-temperature pulverization ratio of the sinter and cause swelling of the ore pellets; the circulated alkali metals attack the refractory lining in the blast furnace and reduce the lining life of the blast furnace; have a detrimental effect on gas permeability , reducing the smelting intensity and causing having scaffold formation on the furnace wall.According to the influence of alkali metals on the smelting of blast furnace, the author combines this thesis with the data of Xiangtan Iron and Steel Company, and puts forward suggestions to prevent the harmful defects of alkali metals through the theoretical analysis, the calculation and the experiences of preventing the harmful defects of alkali metals of the other steel plants. The preventive measures for the harmful defects of alkali metals are as follows: 1), reducing the alkali metals content in the raw materials; 2), increasing the MgO content of the sinter , decreasing the basicity of slag , decreasing the Si content of the pig iron, increasing relative slag volume; 3) , introducing prereduced ore pellets or partly reducted sinter; 4)increasing the ability of coke resisting alkali metals; 5), using refractories that have the ability of resisting corrasion of alkali metals; 6) , cleaning the blast furnace periodically. The above recommendations are necessary for decreasing the circulation and accumulation of alkali metals effectively in blast furnace, reducing the harmful influence of alkali metals on blast furnace, increasing the smelting intensity, decreasing the coke rate, improving the gas permeability.