Method of hot metal dephosphorization treatment

A treatment method and molten iron technology, applied in the manufacture of converters, etc., can solve problems such as heavy burden

Active Publication Date: 2008-11-12
JFE STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the burden of cooling it to an appropriate temperature is large, and a method for improving dephosphorization efficiency more effectively is required

Method used

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  • Method of hot metal dephosphorization treatment
  • Method of hot metal dephosphorization treatment
  • Method of hot metal dephosphorization treatment

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0052] The molten iron tapped from the blast furnace was desiliconized in a blast furnace casthouse, and then transported to a converter with a capacity of 300 tons, where dephosphorization was performed a total of four times (Examples 1 to 4 of the present invention). The phosphorus concentration of the molten iron before the dephosphorization treatment was uniformly 0.12% by mass, and the phosphorus concentration of the molten iron after the dephosphorization treatment was 0.020% by mass or less, and the iron yield was set at 98% or more. The yield of iron (η) is the total mass (Wo+Ws) of the mass (W) of molten iron that is tapped after dephosphorization relative to the mass (Wo) of molten iron charged into the converter and the mass (Ws) of scrap metal Calculated by expressing (η=100W / (Wo+Ws)) in percentage.

[0053] The dephosphorization treatment is carried out using a top blowing oxygen blowing pipe, and the top blowing oxygen blowing pipe has two separate supply systems...

Embodiment 2

[0064] The molten iron tapped from the blast furnace was desiliconized using a blast furnace sand bed, and then transported to a converter with a capacity of 300 t, where a total of 15 dephosphorization treatments were performed (Examples 11 to 25 of the present invention). The dephosphorization treatment was carried out in the same manner as in Example 1, and the phosphorus concentration of the molten iron after the dephosphorization treatment was 0.020% by mass or less, and the iron yield was 98% or more as targets.

[0065] As iron oxide, iron ore with an average particle size of 100 μm was used. The iron oxide is supplied from the top-blown oxygen blowing pipe based on the transport gas and fed from the top of the hopper on the furnace.

[0066] As the dephosphorization refining agent, quicklime powder (average particle size less than 1 mm) supplied from the supply system of the gaseous oxygen source and lump lime (average particle size about 10 mm) fed from the upper side...

Embodiment 3

[0074] The molten iron tapped from the blast furnace was desiliconized using a blast furnace sand bed, and then transported to a converter with a capacity of 300 t, where dephosphorization treatment was performed twice in total (Examples 31 to 32 of the present invention). As the bottom blowing gas, the inner tube of the tuyere of the double tube structure at the bottom of the converter is used as the stirring gas to correspond to about 0.8Nm per 1 ton of molten iron 3 Oxygen is blown in at a flow rate of / min. Dephosphorization treatment was performed in the same manner as in Example 1, except that propane gas for cooling the tuyeres was blown in from the outer pipe. As iron oxide, rolled scale with an average particle size of 500 μm was used. The phosphorus concentration of the molten iron after the dephosphorization treatment is 0.020% by mass or less, and the iron yield is 98% or more as targets.

[0075] Table 3 shows the molten iron components and operating conditions ...

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Abstract

A method of hot metal dephosphorization treatment, comprising adding a dephosphorization refining agent composed mainly of CaO and reducing the added dephosphorization refining agent composed mainly of CaO to slags to thereby accomplish dephosphorization of the hot metal, wherein a gaseous oxygen source is fed from one supply system to a surface of hot metal bath and a solid oxygen source is fed from another supply system to a surface of hot metal bath in the vicinity of the site where the gaseous oxygen source is fed by the use of carrier gas. Thus, without the use of any medium solvent containing fluorine, there can be accomplished dephosphorization treatment with dephosphorization efficiency and iron yield equal to or higher than those of the prior art.

Description

technical field [0001] The invention relates to a dephosphorization treatment method of molten iron, in particular to a method capable of effectively dephosphorizing molten iron with a high iron yield without using a fluorine source as a cosolvent. Background technique [0002] In the steelmaking process using blast furnace molten iron, before decarburization and blowing in the converter, the molten iron is usually dephosphorized by using oxygen and solid iron oxide to oxidize and remove most of the Si and P contained in the molten iron, or by using a desulfurizer. So-called molten iron pretreatment such as molten iron desulfurization treatment in which S contained in molten iron is removed in a reducing atmosphere. [0003] In recent years, the quality requirements required for iron and steel products have increased and become stricter than before, and the reduction of phosphorus concentration has been required to be higher than the previous level. In order to meet this qu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C1/02C21C5/32
CPCC21C1/02C21C1/025C21C7/064C21C7/0645C21C7/072
Inventor 内田祐一鹫尾胜井上明彦村木靖德岸本康夫藤城正太郎
Owner JFE STEEL CORP
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