Double-smelting dephosphorization process for high-phosphorus molten iron

Abstract

The invention discloses a double-smelting dephosphorization process for high-phosphorus molten iron. The double-smelting dephosphorization process comprises a pre-dephosphorization process and a converter smelting process. The pre-dephosphorization process comprises the steps that pre-dephosphorization is performed by the adoption of a pre-dephosphorization furnace; a desiliconization slagging material is added to the high-phosphorus molten iron, and oxygen injection is performed for desiliconization slagging; the desiliconization slagging material is put into the furnace after desiliconization slagging, a solid oxygen agent is put into the furnace after dephosphorization slagging, meanwhile dephosphorization agent injection is performed, and inert gas bottom-blowing is performed so that mixing can be strengthened; and the pre-dephosphorized molten iron passes iron-slag separation equipment and then enters the converter smelting process. The dephosphorization process has the beneficialeffects of being stable, low in temperature, large in treatment capacity and the like, and the problem about high-phosphorus ultrahigh-phosphorus molten iron dephosphorization is solved thoroughly. The double-smelting dephosphorization process is suitable for high-phosphorus molten iron and ultrahigh-phosphorus molten iron, and the dephosphorization rate of pre-dephosphorization can reach 64-71%.According to the process, the molten iron pre-dephosphorization furnace and converter double-smelting are adopted, the high-phosphorus ultrahigh-phosphorus molten iron smelting operation can be achieved, the converter steelmaking load is lowered greatly, steelmaking is more efficient, and the smoothness and stability of the production procedures are guaranteed.

Description

technical field [0001] The invention relates to a method for dephosphorizing molten iron, in particular to a double-smelting dephosphorization process for high-phosphorus molten iron. Background technique [0002] Phosphorus in steel is [Fe 2 P] exists in the form and can also be represented by [P]. Phosphorus can improve the strength of steel, but with the increase of phosphorus content, the plasticity and toughness of steel decrease (especially the decrease of low temperature impact toughness), even if the brittleness of steel increases, it is usually called "cold brittleness". As the content of C, N, and O increases, the harmful effect of phosphorus intensifies, so it becomes one of the main removal elements in steel. [0003] At present, the commonly used dephosphorization methods in industrial production are mainly: powder spraying dephosphorization on ladles and torpedo tank cars, converter dephosphorization and electric furnace dephosphorization. The hot metal ladl...

AI Technical Summary

Problems solved by technology

Converter dephosphorization process uses massive lime and ore, and the phosphorus in hot metal is generally required to be less than 0.15%. Under the condition of hot metal pretreatment temperature, the slag alkalinity of lime and ore slagging mode is low, and [P] can be stably controlled after processing low phosphorus hot metal At 0.020-0.040%, it is impossible to process high-phosphorus molten iron

[0005] At present, the traditional electric furnace dephosphorization has problems such as slow slag melting speed in the process of slag making and dephosphorization, insufficient stirring strength of molten pool, slow mass transfer between slag and steel and slow dephosphorization reaction speed, etc. The amount of slag is large and the amount of decarburization is large. The dephosphorization effect is poor, and it is difficult to meet the requirements of efficient dephosphorization in the smelting process

[0006] In recent years, with the rapid development of the iron and steel industry, low-phosphorus iron ore is on the verge of depletion worldwide, and the mining and smelting of high-phosphorus iron ore has gradually been put on the agenda. The use of high-phosphorus ore in blast furnaces has resulted in high phosphorus content in molten iron. The traditional smelting method cannot meet the production needs, and it is easy to cause high phosphorus in some molten steel, which has a serious impact on the quality and cost of molten steel

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