Evaluating the effectiveness of using coke breeze in blast-furnace smelting
| Autor: | V. A. Gostenin, S. N. Pishnograev, A. V. Chevychelov, V. P. Gridasov, G. N. Logachov |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | Metallurgist. 56:87-90 |
| ISSN: | 1573-8892 0026-0894 |
| DOI: | 10.1007/s11015-012-9540-9 |
| Popis: | The expediency of using various amounts of nut coke in blast-furnace smelting is evaluated in relation to the quality of the skip coke. Data from blast-furnace operation are analyzed to obtain relations expressing the dependence of the consumption of nut coke on the unit consumption of skip coke and its abradability index M 10 . A blast furnace can run smoothly with the use of nut coke if its concentration in the charge does not exceed 20 kg/ton pig iron and the abradability index of the skip coke is satisfactory (M 10 ≤ 9.0%). The average value of the coke-substitution equivalent was determined to be 0.67 kg/kg nut coke. This interest stems from the possibility of reducing unproductive losses of coke, optimizing the gasdynamic regime in the smelting operation, and improving its technical-economic indices. Analytical studies (1) show that mixing nut coke with the iron-ore-bearing part of the blast-furnace charge improves the charge's gas permeability. The optimum dimensions of nut coke used for this purpose range from 10-15 mm to 35-40 mm. The gas permeability of the charge is most favorably affected by charging nut coke in such a way that it comprises 20-30% of the initial portion of the coke charge. Such an approach improves the charge's gas permeability by 11.5-13.5%. An analysis of the performance of blast furnaces at European plants operated with a low (down to 300 kg/ton pig iron) consumption of coke showed that lowering coke consumption from 350 to 270-290 kg/ton pig leads to a small (10%) increase in the thickness of the ore lenses and a significant decrease in the thickness of the layers of coke - from 48 to 34 cm. Nut coke is mixed with ore and charged into the peripheral zone of the furnace to keep it from descending into the lower layers of the cohesion zone (2). Due to an acute shortage of coke for the blast furnaces at the West Siberian Metallurgical Combine (ZSMK), the combine conducted commercial heats with the use of fine fractions of coke (36-25 mm) in the charge (3). Pig-iron output decreased 1.0-6.6% when such fines were used to make up as much as 22% of the charge, with the exact fines content of the charge depending on the smelting conditions. A decrease in iron output of this magnitude is equivalent to a 0.2-0.4% decrease in the production of pig iron for each 1% content of fines. Unit coke consumption increased 0.8-1.0%, or by 0.19-0.17% for each 1% content of fines. The use of coke breeze at the above-indicated rates also adversely affected the drainage capacity of the hearth. The technical-economic indices obtained on a furnace equipped with a rotary charge distributor showed that it is possible to maintain forced operation of the furnace when the content of the 36-25 mm of coke ranges up to 25%. The inclu- sion of more than 30% coke breeze reduces smelting rate and aggravates the operation of the hearth. Data obtained by the central test laboratory of the combine were used to analyze the use of nut coke as a substitute for regular metallurgical coke at plants in Germany, France, Belgium, the Netherlands, Russia, and Ukraine. The relationships |
| Databáze: | OpenAIRE |
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