New technological solutions to protect the lining of blast-furnace hearths

The use of schungite as a partial replacement for coke is practiced in Russia at a number of metallurgical plants, both in the production of foundry iron (its primary use) and in making conversion pig iron. The largest amount of coke is replaced when foundry iron is being made, the replacement coefficient in this case having a value within the range 0.8–1.3. Studies that included continuous monitoring of the temperature of the carbon blocks in blast furnaces with volumes of 1719, 3200, and 5580 m³ unambiguously demonstrate that the thickness of the slag crust in blast furnaces increases with the use of schungite. Protecting the lining of the hearth through the use of schungite is also accompanied by a decrease in coke consumption. __________ Translated from Metallurg, No. 8, pp. 53–57, August, 2007.     

Effect of coke quality on blast-furnace performance indices

The quality of coke has a strong effect on the performance indices of a blast furnace. For a furnace to operate with high productivity and a low coke rate, it is necessary to use coke with high strength characteristics. The Novolipetsk Metallurgical Combine has conducted studies of the effect of coke quality on the operation of blast furnaces of different sizes. The quality of the coke was evaluated on the basis of the following indices: CSR, CRL, the cold-strength indices M₁₀ and M₂₅, and the integral coke-quality index I_g.c used by the Sidmar company. Furnace productivity, coke rate, and the totterman index (DMI) were also used for the sake of comparison.     

A study of the phase composition of iron-ore briquets to assess their behavior in a blast furnace

We study a mechanism for maintaining the strength of cement-bonded iron-oxide-bearing briquets when heated under reducing conditions. These briquets retain their strength when heated in a reducing atmosphere: up to 700–750°C, strength retention is due to the cement stone; strength retention under further heating is due to the continuous metal shell formed on the surface of the briquet as the iron oxide in the surface layer of the briquet is reduced to iron. Fabrication and usage of briquets of iron-ore concentrate can be recommended as a wash material for blast furnaces. Disperse materials containing SiO₂ and MgO should be added to the charge during fabrication of the briquets in order to improve the washing properties of briquet slag.     

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Translated from Metallurg, No. 4, pp. 26–27, April, 1996.     

Effect of enriching the blast with oxygen on the production cost of pig iron

Conclusion By mathematically modeling the blast-furnace smelting of conversion pig iron with a change in the oxygen content of the blast from 21 to 30% and a change in blast temperature from 800 to 1400°C, it was possible to determine how blast temperature affects the increases that occur in furnace productivity, coke rate, and pig-iron cost when blast oxygen content is increased by 1% within the ranges from 21 to 25% and from 25 to 30%. Under the furnace operating conditions that were examined, the savings in coke realized when the blast is enriched with oxygen decrease as blast temperature increases. In fact, coke rate increases at blast temperatures above 1100°C when the blast is enriched with oxygen in the range 25–30%. The effect of oxygen enrichment on pig-iron cost within this concentration range is negative throughout the range of blast temperatures examined. Adding more oxygen to the blast reduces the production cost of the pig iron only when blast oxygen content is within the range 21–25% and blast temperature is no greater than 1000–1100°C. At higher temperatures, adding more oxygen to the blast is economically inexpedient even within the lower ranges of oxygen content. Moscow State Institute of Steel and Alloys. Translated from Metallurg, No. 5, pp. 43–44, May, 1999.