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

A converter smelting and control method technology, applied in the direction of manufacturing converters, improving process efficiency, etc., can solve the problem that it is difficult to reach the molten steel at the end of smelting, and achieve the effect of ensuring the fluctuation range

Inactive Publication Date: 2013-05-15
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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. T

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Weigh 72.2kg / t of primary slag according to the amount of each ton of steel material (hot metal + scrap), of which active lime is 45.7kg / t, lightly burned dolomite is 11.4kg / t, and lightly burned magnesium balls are 6.2kg / t, sintering return ore is 4.2kg / t, slagging agent is 2.4kg / t, miscellaneous ash is 2.4kg / t; and the secondary total slag material with an amount of 44.6kg / t per ton of steel material, of which active lime is 27.5kg / t, 2.7kg / t for lightly burned dolomite, and 14.4kg / t for sintering and returning ore. In order to ensure the phosphorus content of the end point molten steel, the phosphorus content in the active lime is 0.005%, the phosphorus content of light-burned dolomite and light-burned magnesium ball slag is 0.027%, the phosphorus content in sintering and returning ore is 0.043%, slagging agent and The phosphorus content in miscellaneous ash is 0.030%.

[0022] Then proceed as follows:

[0023] (1) Low-phosphorus steel with a phosphorus content of...

Embodiment 2

[0033] Compared with Example 1, this example differs in that 30% of the oxidized slag remains in the furnace after tapping, the amount of smelting slag added, the primary slag pouring temperature, and the carbon content at the end point. In this example, 74.9kg / t of primary slag is added according to the amount of each ton of iron and steel material (hot metal + scrap steel), of which active lime is 35.1kg / t, lightly burned dolomite is 20.2kg / t, and lightly burned magnesium balls are 6.4kg / t, 13.2kg / tt for sintering and returning to ore; Return ore is 12.3kg / t. In this embodiment, the primary slagging temperature is controlled to be 1403° C., the carbon content of the molten steel at the end point of the converter is 0.04%, and the phosphorus content of the molten steel at the end point is 0.0028%.

Embodiment 3

[0035] Compared with Examples 1 and 2, this example differs in that 35% of the oxidized slag remains in the furnace after tapping, the amount of smelting slag added and the carbon content at the end point. In this example, 68.4kg / t of primary slag is weighed according to the amount of each ton of steel material (hot metal + scrap steel), of which active lime is 39.4kg / t, lightly burned dolomite is 13.2kg / t, and lightly burned magnesium balls are 6.3kg / t, sintering and returning 9.5kg / tt; and 66.5kg / t secondary total slag material per ton of steel material, of which active lime is 26.1kg / t and lightly burned dolomite is 11.3kg / t , 2.4kg / t for lightly burned magnesium balls, and 26.6kg / t for sintered ore return. In this embodiment, the temperature at the end point of the converter is 1640°C, the carbon content at the end point of the converter is 0.05%, and the phosphorus content in the molten steel at the end point is 0.0018%.

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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...

Claims

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Application Information

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IPC IPC(8): C21C5/28C21C5/36
CPCY02P10/20
Inventor 李晶姚永宽蔡可森武贺吴国平曹余良李翔周朝钢樊攀
Owner UNIV OF SCI & TECH BEIJING
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