Optimum technologies for the blow-in of blast furnaces

Duration of blast furnace blow-in period and the rate of approach to normal smelting conditions varies from furnace to furnace and is not closely regulated, since it deals with transient conditions (compared to the relatively more stable regime of normal smelting) as is described and discussed in de...

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Bibliographic Details
Published in:Metallurgist (New York) 1999-01, Vol.42 (5-6), p.212-215
Main Authors: Rostovskii, A V, Paren'kov, A E, Loginov, V N, Gavrilyuk, G G, Al'ter, M A
Format: Article
Language:English
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Summary:Duration of blast furnace blow-in period and the rate of approach to normal smelting conditions varies from furnace to furnace and is not closely regulated, since it deals with transient conditions (compared to the relatively more stable regime of normal smelting) as is described and discussed in detail in this article. Faulty blow-in can adversely affect furnace and refractory lining life as well as generating large amounts of scrap and excessive noxious emissions. Introduction of new blow-in methods makes it possible to achieve steady state smelting much sooner. Among these techniques are natural gas injection (every 9.5 hrs) which achieved normal smelting parameters in three days. Nitrogen injection improves heating of the stock and the ore burden by increasing the volume of hearth gases (which resulted in one blow-in time being reduced threefold). In another instance oxygen injection into the central part of the hearth increased productivity by 40% during the blow-in period. Blow-in indices for 7 blast furnaces are listed in table 1. along with a discussion of the changes in chemistry as the blow- in process proceeds. The parameters of the blast and tuyeres should provide for blast velocities up to 200 m/sec. It is recommended that different blast additions (oxygen, natural gas, coke-oven gas, steam) be employed at the beginning of blow-in to activate the central zone of the furnace. Blast parameters must be chosen to keep the theoretical combustion temperature during the initial blow-in below 1800 deg C to avoid formation of volatile silicon monoxide. Charge materials should ensure optimum slag composition to balance lining protection (high viscosity) with suitably fluid slagging to extract undesired ingredients (S, P, etc.,) from the molten metal.
ISSN:0026-0894