JP2010222660A - Method for refining molten steel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for refining molten steel with which in the case of charging the molten iron, it can be restrained that combustibles in iron-scrap are ignited and flame or black smoke caused by the ignition of the combustibles, is spouted from the furnace opening hole of a converter without needing much facility cost. <P>SOLUTION: When the molten iron 10 is charged into the converter 1 after charging the iron-scrap 8 containing the combustibles into the converter 1, the converter 1 is returned back to the erected state after charging the iron-scrap 8 into the converter 1, and the molten iron 10 is charged into the converter 1 after igniting the combustibles in the iron-scrap 8 by blowing oxygen-gas 9 into the converter 1 in the returned state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for refining molten steel, and more particularly, to a method for refining molten steel using iron scrap containing combustible materials as a cold iron source for molten steel refined in a converter.

Generally, when refining molten steel in the converter, hot metal is charged into the converter as an iron source for the molten steel. However, if the amount of molten iron in the converter is small, the shortage of molten iron is compensated. Therefore, iron scraps such as used automobiles and waste belt materials are charged into the converter as a cold iron source of molten steel (see, for example, Patent Document 1). In this case, if combustible materials such as resin and oil are contained in the iron scrap, the combustible material contained in the iron scrap is ignited when the hot metal is charged into the converter after the iron scrap is charged in the converter. However, there is a problem that flames and black smoke are ejected from the furnace port of the converter due to the ignition of the combustible material.
Therefore, in order to solve such problems, when iron scrap is charged into the converter containing hot metal, the converter is sprayed in a mist from the upper part of the converter opening toward the furnace opening. A method of charging iron scrap inside is proposed (see Patent Document 2).

JP 2001-59110 A Japanese Patent Laid-Open No. 2005-87992

According to the above-described method, when iron scrap is charged into a converter containing molten iron, combustibles contained in the iron scrap are ignited and flame and black smoke are prevented from being ejected from the furnace port of the converter. It is possible. However, since it is necessary to newly install watering equipment for spraying the cooling water in a mist form from the upper part of the converter opening to the furnace opening, there is a problem that a great equipment cost is required. In addition, if the cooling water sprayed from the upper part of the converter entrance to the furnace entrance enters the converter, a steam explosion may occur when the hot metal is charged into the converter, or it may be lined in the converter. There was also a possibility that the firebrick was damaged.
The present invention has been made in view of the above-mentioned problems, and it is a great deal of fire that combustible materials of iron scrap are ignited when hot metal is charged, and that flames and black smoke are ejected from the furnace port of the converter due to the ignition of combustible materials. An object of the present invention is to provide a method for refining molten steel that can be suppressed without requiring any equipment cost.

To solve the above problems, refining method of molten steel according to the present invention, after the iron scrap containing combustible materials were charged to the converter in a cold iron source of the molten steel being refined in a converter furnace, the converter A molten steel refining method for refining molten steel by charging molten iron in the furnace, wherein after the iron scrap is charged into the converter, the converter is returned to an upright state, and in this state the inside of the converter After the oxygen gas is blown into the flammable material to burn the combustible material, the hot metal is charged into the converter.
In the molten steel refining method according to the present invention, the amount of iron scrap charged into the converter is preferably 3% to 10% of the total amount of molten iron and iron scrap.

  According to the method for refining molten steel according to the present invention, the combustible material of iron scrap is ignited at the time of molten metal charging, and the flame and black smoke are ejected from the furnace port of the converter due to the ignition of the combustible material. It can suppress without requiring.

It is a figure which shows an example of the converter equipment used for the refining method of the molten steel which concerns on this invention. It is a figure which shows one Embodiment of the refining method of the molten steel which concerns on this invention.

Hereinafter, a method for refining molten steel according to the present invention will be described with reference to the drawings.
An example of converter equipment used in the method for refining molten steel according to the present invention is shown in FIG. The converter equipment shown in FIG. 1 includes a converter 1 that can tilt in the left-right direction in the figure around a trunnion shaft (not shown), and oxygen gas is blown into the converter 1 above the converter 1. An upper blowing lance 2 is provided so as to be movable up and down, and an exhaust gas hood 3 for collecting exhaust gas discharged from the converter 1 is provided. 1 includes a gantry 6 on which the hot metal ladle 4 and the scrap chute 5 are placed. Above the gantry 6, the hot metal and scrap chute 5 contained in the hot ladle 4 are provided. A crane 7 is provided for charging the iron scrap loaded into the converter 1 into the converter 1.
In the case of refining molten steel by charging iron scrap and hot metal containing combustible material into the converter 1 of the converter facility shown in FIG. 5, iron scrap 8 is charged into converter 1 within a range of 3% to 10% of the total amount of molten iron and iron scrap (see FIG. 2A).

Next, after the converter 1 is returned to an upright state so that the furnace port of the converter 1 faces directly above, oxygen gas 9 is blown into the converter 1 from the top blowing lance 2 (see FIG. 2B). ). At this time, the combustible material of the iron scrap 8 charged in the converter 1 burns together with the oxygen gas 9 blown into the converter 1. Further, black smoke and dust generated by the combustion of combustible material flow into the exhaust gas hood 3 and pass through the exhaust gas hood 3 and are collected by a dust collector (not shown).
If the combustible material of the iron scrap 8 is burned out by the oxygen gas 9 blown into the converter 1 from the top blowing lance 2 in this way, the converter 1 is inclined again and then the converter from the hot metal ladle 4 1 is charged with hot metal 10 (see FIG. 2C). At this time, the iron scrap 8 in the converter 1 is melted by the hot metal 10 charged in the converter 1 and becomes molten steel together with the hot metal 10.

  As described above, the iron scrap 8 containing combustible material is charged into the converter 1, and then the molten steel 10 is charged into the converter 1 to refine the molten steel. After the converter 1 is charged, the converter 1 is returned to an upright state, and in this state, the oxygen gas 9 is blown into the converter 1 from the top blowing lance 2 to burn the combustibles of the iron scrap 8, and then the converter 1 When the hot metal 10 is charged into the hot metal 10, the combustible material of the iron scrap 8 is ignited when the hot metal 10 is charged, and flame and black smoke are prevented from being ejected from the furnace port of the converter 1 due to the ignition of the combustible material. Further, unlike the one disclosed in Patent Document 2, it is not necessary to newly install a watering facility for spraying cooling water in a mist form from the upper part of the converter to the furnace opening.

Therefore, the combustible material of the iron scrap 8 is ignited when the hot metal 10 is charged, and flames and black smoke are prevented from being ejected from the furnace port of the converter 1 by igniting the combustible material without requiring a large facility cost. Can do.
Using H2 scrap graded by the Japan Iron Source Association as iron scrap charged into the converter, the ratio of H2 scrap to the total charge of hot metal and iron scrap is 0%, 3%, 5 Table 1 shows the results of investigating the occurrence of flame and black smoke generated in the converter when the ratio is 10% and 10%.

In Table 1, “Minor”, “Medium” and “Large” represent the degree of generation of flame and black smoke in the converter.
As shown in Table 1, when oxygen gas was blown into the converter into which iron scrap was charged and the combustibles of iron scrap were not burned in advance, flame and black smoke increased as the proportion of H2 scrap increased. When the rate of occurrence increases, when oxygen gas is blown into the converter into which iron scrap is charged and the combustibles of iron scrap are burned in advance, even if the proportion of H2 scrap is 3% to 10%, flame It can be seen that the incidence of black smoke is low.
Therefore, it is possible to suppress the combustible material of iron scrap from being ignited when the hot metal is charged, and to prevent the flame and black smoke from being ejected from the furnace port of the converter due to the ignition of the combustible material without requiring a large facility cost.

Also, when the blowing amount of oxygen gas blown into the converter prior to charging the molten iron to H2 scrap per ton of 20 to 70 nm ^3, the table can be suppressed the occurrence of fire and smoke in the "minor" 1 It can be seen from the experimental results shown in. Therefore, it is preferable that the amount of oxygen gas blown into the converter prior to charging the hot metal is 20 to 70 Nm ³ / H 2 -t.
In the above-described embodiment of the present invention, the oxygen gas 9 is blown from the top blowing lance 2 into the converter 1 in which the iron scrap 8 is charged, and the combustible material of the iron scrap 8 is burned. In the case of a bottom blown converter, oxygen gas 9 may be blown from the bottom of the converter to burn the combustible material of the iron scrap 8.
Further, oxygen gas may be blown into the converter from the tuyere formed at the bottom of the converter, or oxygen gas may be blown into the converter from both the upper blowing lance and tuyere.

  DESCRIPTION OF SYMBOLS 1 ... Converter, 2 ... Top blowing lance, 3 ... Exhaust gas hood, 4 ... Hot metal ladle, 5 ... Scrap chute, 6 ... Mount, 7 ... Crane, 8 ... Iron scrap, 9 ... Oxygen gas, 10 ... Hot metal.

Claims (2)

In a method for refining molten steel, iron scrap containing combustible materials as a cold iron source for molten steel refined in a converter is charged into the converter, and then molten iron is charged into the converter to refine the molten steel. There,
After charging the iron scrap into the converter, the converter is returned to an upright state. In this state, oxygen gas is blown into the converter to burn the combustible material, and then the converter is put into the converter. A method for refining molten steel, characterized by charging molten iron.   The method for refining molten steel according to claim 1, wherein the amount of iron scrap charged into the converter is 3% to 10% of the total amount of molten iron and iron scrap.

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