JPS63210230A - Converter blowing method - Google Patents

Abstract

PURPOSE:To uniformize the in-furnace reaction particularly in the end period of blowing so as to accelerate in-furnace equil. reaction and to prevent sloppy, by blowing an inert gas together with gaseous oxygen into a converter from a lance disposed on the upper part of the converter thereby stirring a steel bath. CONSTITUTION:The inert gas is blown together with the oxygen into the steel bath from the lance 11 made into the construction formed with a flow passage 13 for the inert gas such as Ar on the inside and a flow passage 12 for the oxygen on the outside. The flow rate of the inert gas is afterward increased and the flow rate of the oxygen is decreased when the stirring force in the end period of blowing is needed. The formation amt. of the (FeO) in the slag formed at the fine point is thereby decreased and the stirring power needed in the end period of blowing is assured, by which the compsn. of the slag in the furnace, more particularly the total content of Fe in the slag are uniformized to accelerate the in-furnace equil. reaction and to prevent slopping. Since the inert gas passes the central part in the above-mentioned lance 11., the nonuniformith in the concn. of the (FeO) in the fire point is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a converter blowing method, particularly to a blowing method at the final stage of blowing.

[Prior Art] Generally, in the blowing process of a converter, oxygen is blown into the raw material in the furnace body through a lance, and carbon in the steel bath is combusted to deoxidize the raw material. (Fed) in the slag is thought to be generated at the flash point, and the amount of it generated is particularly large at CT (
It increases rapidly after transition [C]). Conventionally, in order to prevent rapid formation of slag (Fed) at the end of blowing, that is, rapid consumption of iron in the steel bath, the amount of oxygen blown from the lance was increased at the end of blowing to increase the slag stirring power. By this, the slag composition in the furnace is made uniform, and the slag (Fed
) generation is suppressed.

[Problems with the prior art] However, although this method can relatively suppress the increase in the amount of (Fed) produced in the slag, the amount of (Fed) produced at the ignition point is extremely high due to the increased amount of oxygen blown into the slag. This increased the deviation from equilibrium within the reactor and caused sloping.

The present invention was made in view of the above circumstances, and during blowing,
In particular, at the end of blowing, the formation of (Fe○) at the hot point is suppressed, and the slag composition in the furnace, especially the total amount of Fe in the slag, is made uniform, promoting equilibrium reactions in the furnace, preventing slopping, etc. The purpose is to provide a converter blowing method.

[Means and effects for solving conventional problems] The present invention is a converter blowing method in which inert gas is blown in and stirred together with oxygen gas from a lance placed in the upper part of the converter.

According to this method, since the inert gas is mixed with oxygen for blowing, the amount of blowing increases, and even if the amount of oxygen is reduced, especially at the end of blowing, the slag can be sufficiently stirred, and the slag (Fe○ )
This suppresses the formation of slag, homogenizes the composition of slag in the furnace, and promotes the equilibrium reaction in the furnace.

[Example] The present invention will be described below with reference to illustrative embodiments.

In the present invention, an inert gas is simultaneously blown into the steel bath when oxygen is blown into the steel bath from the lance. The structure of the lance 11 is, for example, the first
As shown in the figure, the structure is such that an inert gas flow path 12 is formed inside and an oxygen flow path 13 is formed outside. Examples of the inert gas include Ar, N2, CO1CO2, and a mixed gas thereof.

In the early and middle stages of blowing, the oxygen flow rate is 75 per 300 tons of steel bath.
0 Nm3/min ~900 Nm3. 'man,
The inert gas flow rate is preferably 0 to 5 ONm3/min. Then, from the time when stirring power is required at the end of blowing (after CT), the flow rate of the inert gas is increased and the flow rate of oxygen is decreased.

The inert gas flow rate and oxygen flow rate here are 500 to 70 ONm3/min and 100 ONm3/min, respectively, per 300 tons of steel bath.
-300 Nm37m1n is preferred.

According to this method, since the oxygen flow rate is reduced at the final stage of blowing, the amount of slag (Fed) produced at the fire point can be suppressed. Moreover, since the amount of inert gas blown in from the lance is increased, the stirring power required at the final stage of blowing can be secured. As a result, the slag composition in the furnace, particularly the total amount of Fe in the slag, can be made uniform, the equilibrium reaction in the furnace can be promoted, and slopping can be prevented. In addition, if the lance shown in Figure 1 is used, inert gas passes through the center, so that (F
ed) Non-uniformity of concentration can be eliminated.

Next, when blowing a 300 ton steel bath in a converter, a flow rate of 800 Nm3/min of oxygen and a flow rate of 4ONm were added from a lance.
Inert gas consisting of CO + GO2 was blown into the furnace at a rate of 3/min, and then the oxygen flow rate was 300 Nm3 after CT.
/min and the inert gas flow rate to 600 Nm3/min.
I turned it up to min and blew it. As a result, as shown in FIG. 2, it can be seen that the amount of (Fed) produced at the flash point is significantly suppressed. On the other hand, blowing midstream 1800 Nm3/
Blow oxygen at min (no inert gas), 0
When blowing is carried out with the oxygen flow increased to 900 Nm3/min (without injecting inert gas), as shown in Figure 3, (Fed) at the fire point increases extremely. I can see that

[Effects of the Invention] As explained above, according to the present invention, the amount of (Fed) generated at the flash point is suppressed by reducing the oxygen injection flow at the end of blowing, and the amount of inert gas injection is reduced. Since the stirring power is increased by increasing the flow rate, it is possible to make the reaction in the furnace uniform, promote the equilibrium reaction in the furnace, and prevent slopping.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic diagram of a converter, FIG. 1(b) is a sectional view showing the structure of a nozzle used in the converter blowing method of the present invention, and FIG.
The figure shows the distribution of the (Fed) production amount in the example.
The figure shows the (Fed) distribution in the conventional method, and FIG. 4 shows the changes in [C] and (Fed) in the steel bath with the passage of blowing time. 11...Lance, 12...Inert gas flow path, 13.
...Oxygen flow path. Applicant's agent Patent attorney Takehiko Suzue (a) Figure 2 Figure 3

Claims (1)

[Claims] A converter blowing method in which oxygen gas and inert gas are injected and stirred through a lance placed at the top of the converter.