Use of nut coke in blast furnaces equipped with compact chute BLT depending on the conditions of process
Background. One of the ways to reduce the specific consumption of coke is the involvement in the iron production technology the nut coke of size 10-25 mm and coke fractions of size 25-40 mm. Their use may reduce the drainage capacity of the hearth. This is particularly evident on the furnaces equipped with compact chute bell-less top (BLT) charging system, working with the lower limiting zone by force interaction between two streams of charge and gas. In this regard, an urgent task for the production of iron is the development of mode of nut use in furnaces with compact chute charging system, excluding its negative effect on the ability of coke filtering head in the hearth. Materials and/or methods. Influence of nut coke consumption, including compensation of its negative effect on the drainage capacity of the hearth, was examined for blast furnaces No.4,6,9,10 JSC "Magnitogorsk Iron and Steel Works", equipped with compact chute BLT. Furnace worked under the bottom (No.6,10) and upper (No.4,9) limiting zones for force interaction between two streams of charge and gas. Results. In the studies as compensatory measures it was appropriate to use the washing materials (manganese or iron ores by JSC "Mikhailovsky GOK" in the amount of 1.7 and 2.9 kg per 1 kg of nuts, respectively). The use of coke with a higher by 0.14 %abs. hot strength or decreased by 0.05 %abs. abrasion eliminated the negative effect of nut consumption in the amount of 4 kg/t of iron. Conclusion. In the studies, using nut coke in an amount up to 12 kg/t of iron in blast furnaces working with the upper limiting zone by gas dynamics not required to compensate its negative effect on hearth drainage. With further increase of the nut consumption the lower zone became as limiting, thus it was necessary to use the compensatory measures.