Method for reducing alkali metal enrichment in blast furnace

Abstract

The invention relates to a method for reducing alkali metal enrichment in a blast furnace. When loads of in-furnace alkali metal oxides are 2.8 to 3.0 kg/t, the blast furnace carries out alkali removing once in each quarter, and the alkali removing period ranges from 15 days to 20 days; in the alkali removing period, the MgO content in slag of the blast furnace is controlled to be 7% to 8%, and the binary basicity of the slag of the blast furnace is controlled not to be larger than 1.15; in the alkali removing period, the temperature of molten iron in the blast furnace is controlled to be 1490 DEG C to 1500 DEG C; the Si content in the molten iron is controlled to be 0.3 percent to 0.35 percent; the Ti content in the molten iron of the blast furnace is controlled to be 0.1 percent to 0.15 percent. The basicity of the slag of the blast furnace is controlled, components and the temperature of the molten iron of the blast furnace are adjusted cooperatively, the discharge rate of the alkali metal is improved, and the alkali metal enrichment is reduced.

Description

technical field [0001] The invention relates to the field of blast furnace ironmaking, in particular to a method for reducing the enrichment of alkali metals in a blast furnace. Background technique [0002] In the blast furnace ironmaking process, alkali metal minerals mainly exist in the form of aluminosilicate and silicate. These alkali metal minerals have a very low melting point and can be melted between 800 and 1000 ° C. When entering the high temperature zone, a part of them enters the slag , part of which is reduced by C to K and Na elements. Since the boiling points of metal K and Na are only 799°C and 822°C, they are immediately gasified and rise with the gas after reduction, and react with other substances under different temperature conditions to convert into cyanide, fluoride and silicate, etc. mostly CO 2 oxidized to carbonate. In the upper middle and low temperature zone of the blast furnace, K and Na are circulated and enriched in the form of metal and car...

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Problems solved by technology

[0003] Alkali metals can reduce the softening temperature of ore, causing the ore to melt and drip before being fully reduced, increasing the heat consumption of direct reduction in the lower part of the blast furnace; it can cause abnormal expansion of pellets and cause serious pulverization; it can strengthen the gasification of coke Reaction ability, so that the strength after the reaction is sharply reduced and pulverized; the air permeability of the material column is seriously deteriorated, which endangers the production and smelting process; Destroys the brick lining and therefore poses a great hazard to blast furnace ironmaking

[0004] Although in the prior art, alkali metal enrichment is often alleviated by reducing the alkali metal content of raw materials and fuels, but the blast furnace will still cause serious alkali metal enrichment after long-term use

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