JPH05279721A - Method for removing slag in converter - Google Patents

Abstract

PURPOSE:To quicken removal of slag, to reduce remained quantity of the slag and to improve the yield of molten steel by blowing oxidizing gas generated in a converter on the slag and foaming so as to make it foam. CONSTITUTION:The converter 1 completed of pre-dephosphorizing treatment and desulfurizing treatment in molten iron is tilted and the oxidizing gas is blown from gas blowing holes 4-1, 4-2 arranged at the interface of the slag 2 and the metal 3. Or, the oxidized gas is blown on the slag 2 surface from the gas blowing holes arranged at the furnace belly part. Then the slag is foamed so as to discharge the slag even at the slight tilting angle.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a converter slag method.

[0002]

2. Description of the Related Art In the hot metal pretreatment step, the slag remaining in the hot metal container induces a decrease in the treatment rate in the next step and a deterioration in the quality of molten steel. Therefore, the slag discharge work requires more complete discharge from the viewpoint of improving the treatment efficiency in the hot metal pretreatment process and ensuring the quality of molten steel.

Conventionally, regarding a method for removing slag in a container,
For example, Japanese Patent Laid-Open No. 59-13009 proposes to insert a rod provided with a slag plate into a furnace and scrape out slag by back and forth movement. Further, Japanese Patent Application Laid-Open No. 52-150309 proposes to insert a slag discharge pipe connected to a vacuum pump into a slag layer and suck the slag layer. Further, JP-A-63-7312
In the gazette, the converter is tilted during the smelting reduction refining of Cr ore, Mn ore, etc. in the converter so that the bottom blown tuyere is converted into slag with N ₂
There is a proposal for a waste treatment method that blows in air.

Further, the applicant of the present invention, in Japanese Patent Application No. 3-124059, discloses a method of discharging metal when smelting metal using a reaction vessel having a plurality of gas injection nozzles in the abdomen. By periodically changing the gas flow rate of
It was proposed that the slag should be undulated to remove the slag.

[0005]

SUMMARY OF THE INVENTION The present invention proposes a converter slag method in which the residual amount of slag is small and the yield of molten steel is excellent.

[0006]

The present invention is a converter slag method for discharging slag generated during preliminary dephosphorization / desulfurization treatment of hot metal in a converter in a formed state. -Forming is performed by blowing an oxidizing gas on the metal interface or by blowing an oxidizing gas on the slag surface.

The present invention will be described below with reference to the drawings. Figure 1
In the above, the converter 1 is tiltable about the tilting central shaft 6 and provided with gas blowing holes 4-1 and 4-2. Gas injection hole 4
The mounting position of is determined by the amount of metal so that it comes to the interface between the molten slag 2 and the molten metal 3.

The converter 1 is tilted, and oxidizing gas is blown through the gas blowing holes 4-1 and 4-2 arranged at the interface between the molten slag 2 and the molten metal 3. At this time the slag is forming,
Slag can be discharged with a slight tilting angle. It should be noted that this blowing can also be performed with a pipe or the like inserted from the furnace opening to the interface. Further, by blowing the gas whose flow rate is changed periodically from the blowing tuyere 5, the waste can be discharged in a shorter time.

FIG. 2 shows another example of the present invention, in which gas injection holes 41-1 and 41-2 are provided in the furnace side. The mounting position of the gas blowing hole 41 is determined by the amount of hot metal and the amount of slag.
After the tilting of the converter 1 is started, the oxidizing gas is blown to the molten slag 2 through the gas blowing hole 41 provided in the abdomen. At this time, the slag begins to form, and slag can be discharged with a slight tilting angle. Further, by blowing the gas whose flow rate is periodically changed from the blowing tuyere 5, the waste can be discharged in a shorter time.

The oxidizing gas in the present invention forms the slag to form a state in which the bulk volume of the slag is increased, and O ₂ and O ₂ —Ar are preferably used. The applicant previously proposed, in Japanese Patent Application No. 2-181989, a molten steel production method in which a hot metal pretreatment step and a decarburization step are integrated.

That is, as shown in FIG. 3, when refining the hot metal to produce molten steel, the first step is to load the hot metal into the converter, and the second step is to add flux and blow oxygen. Then, the P and S refining is performed to reduce the P content and the S content to a predetermined level. As a third step, the converter is tilted to remove the slag produced in the second step, As a 4th step, decarburization to a predetermined C content was performed by adding flux and O ₂ blowing, and as a 5th step, the slag produced in the 4th step was tapped while being left in the converter, and then again. Returning to the first step, the steps up to the fifth step are repeated.

In the third step, however, the oxidizing gas is supplied into the furnace at the same time as the blowing of the inert gas such as N ₂ gas or Ar gas from a plurality of tuyere provided on the slag side of the furnace. By forming the slag foaming, the waste can be discharged more efficiently (hereinafter referred to as Example 3 of the present invention).

[0013]

[Examples] A slag experiment was conducted using a 5t converter, and the results of comparison with the conventional method are shown in Table 1. According to the present invention, the slag ratio could be significantly improved without lowering the yield of molten metal.

[0014]

[Table 1] (Note) Inventive Example 1 is the method of FIG. 1, Inventive Example 2 is the method of FIG. 2, Inventive Example 3 is the method of FIG. 1 and Japanese Patent Application No. 2-181989.
It was decided to use the method of combining the issues.

[0015]

EFFECTS OF THE INVENTION By carrying out the present invention, slag can be swiftly discharged as compared with the conventional slag method, and the residual amount of slag is small, so that the improvement of molten steel yield and the improvement of molten steel quality can be achieved. Is very effective.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is an explanatory diagram of another example of the present invention.

FIG. 3 is an explanatory diagram of still another example of the present invention.

Claims (3)

[Claims] 1. A converter slag method in which slag generated during preliminary dephosphorization / desulfurization treatment of hot metal in a converter is discharged in a formed state. 2. The converter waste slag method according to claim 1, wherein an oxidizing gas is blown into the slag-metal interface to perform forming. 3. The converter waste slag method according to claim 1, wherein an oxidizing gas is blown onto the surface of the slag for forming.