Method for controlling phosphorus content of end point molten steel smelted by a top-bottom combined blowing converter to be less than 30 ppm

Abstract

The invention relates to a method for controlling the phosphorus content of the end point molten steel smelted by a top-bottom combined blowing converter to be less than 30 ppm, and belongs to the field of a steel smelting control method. The method is mainly used for controlling the phosphorus content of the end point molten steel of the top-bottom combined blowing converter to be less than 30 ppm. The method comprises the following steps of: tapping low-phosphorus steel which is smelted last time and has the phosphorus content being less than or equal to 100 ppm and remaining 25%-35wt% of oxidizing slag in the converter; controlling the phosphorus content of molten iron added to the converter to be less than or equal to 0.13%, wherein slag content of the molten iron is less than or equal to 5 kg / t, and the temperature of the molten iron added to the converter is stable and higher than 1300 DEG C; controlling the phosphorus content of steel scrap used for the converter to be less than 0.030%, and controlling the scrap ratio to be 12%-13%; adding slag materials to the converter, wherein the use amount of the slag materials is 115-125 kg per ton of steel materials; controlling the bottom-blowing strength of the converter by adopting a double slag method; controlling the end point carbon of the converter to be less than or equal to 0.06%, the end point temperature to be less than or equal to 1640 DEG C and the end point slag basicity to be 4.2-4.5, and controlling the iron oxide content of the slag to be 18%-25%, thus obtaining the molten steel with the phosphorus content being less than 30 ppm. The method disclosed by the invention is easy and convenient to operate and easy to control.

Description

technical field [0001] The invention relates to a smelting control method, in particular to a control method in which the phosphorus content of molten steel at the end point of smelting in a top-bottom combined blowing converter is lower than 30 ppm. technical background [0002] The blast furnace smelting process is a reducing atmosphere, and the phosphorus in the blast furnace materials (iron ore, sinter, pellets, coke, lime, etc.) is reduced into molten iron, so the blast furnace smelting process cannot be dephosphorized. Under the condition of no hot metal dephosphorization pretreatment, the phosphorus in the hot metal is mainly removed by oxidation in the converter. The process of smelting ultra-low and ultra-low phosphorus steel by using converter deep dephosphorization mainly includes double converter method and traditional steelmaking double slag method or double slag leaving slag method. Converter duplex method is an advanced process for producing ultra-low and ext...

AI Technical Summary

Problems solved by technology

However, conventional converter smelting control methods are difficult to achieve the control requirement that the phosphorus content of molten steel at the end of smelting is less than 30ppm. Therefore, it is necessary to develop a control method for combined blowing converter deep dephosphorization smelting that has a phosphorus content of less than 30ppm at the end of the converter.