JPS58199810A - Operating method of converter - Google Patents

Abstract

PURPOSE:To add effective components inexpensively to molten iron in a high yield by charging the molten iron which is subjected to pretreatments including desiliconization, charging raw material ore thereto for the purpose of controlling the components, and supplying gaseous O2 for combustion in addition to gaseous O2 for blowing. CONSTITUTION:Molten iron which is tapped from a blast furnace is subjected to molten iron pretreatments including at least desiliconization, and said molten iron 3 is charged into a converter 1. Gaseous O2 4a for blowing is blown through the main nozzle 2a of a lance 2 and the molten iron is subjected to converter blowing. Gaseous Ar for stirring is blown according to need through bottom nozzles 1a, 1b- to effect composite blowing. On the otherhand, mainly Fe ore, Cr ore or Ni oxide is charged for the purpose of controlling components into the converter 1 through a chute 5 in the middle period of blowing. Gaseous O2 4b for combustion from the sub nozzle 2b provided around the nozzle 2a in order to supply the heat required for reduction melting of the raw material ore is blown to the surface of the molten iron 3 to burn the converter generated gas consisting essentially of Co generated during the blowing.

Description

[Detailed description of the invention] The present invention applies to various ferroalloys used to adjust the concentration of components such as F, Or, Ni, etc. when melting molten steel containing Or or N1 in a converter blower. Change, νe
This paper proposes a converter operating method that can add raw materials containing ore, (3r ore, or N1 oxide) and maintain a high yield of its active ingredients.

When melting molten steel containing Or or N1 by converter blowing,
Add ferroalloy appropriately into the converter to add Fe.

Conventionally, adjustment of the concentration of components such as Or and N1 has been carried out, but since various ferroalloys are expensive, it is desired to develop other methods for adjusting the concentration of components.On the other hand, these raw material ores (% It is also practiced to add Fe ore to the converter, but this is mainly done to cool the hot metal tapped from the blast furnace or the hot metal that has been subjected to bath iron pretreatment. It is added as part of the various coolants introduced into the furnace, and cannot be used as an alternative to adding ferroalloy. This is because the amount of raw material that can be reduced and melted is determined, and there is a natural limit to the amount of raw material added. on the other hand,
When blowing is performed to produce a large amount of slag, even if a large amount of raw material is added, the yield of the effective ingredients that will be reduced and melted into the molten iron will be low. Therefore, in practice, adding large amounts of each raw material is rarely done.

The present invention aims to adjust the components of IFe, Or, Ni, etc. in finished steel by introducing a large amount of raw material ore into molten iron without using expensive ferroalloy at the time of steel tapping in a converter, and by increasing the yield of the effective components. The purpose is to provide a converter operating method that allows the addition of gas to the converter, and for this purpose, in order to supply the heat for reducing and melting each raw material from another source, in addition to the blowing Os gas, O gas for combustion is introduced into the converter. The gas generated in the converter will be combusted in the converter.

That is, in the converter operating method according to the present invention, when melting molten steel by converter blowing, hot metal that has been subjected to desiliconization and/or dephosphorization master bath pig iron pretreatment is charged into the converter, Fe for component adjustment
Raw material ore such as ore, Cr ore, or N1 oxide is charged and heated to 0.00 mm for blowing. It is characterized by supplying combustion O and gas into the converter together with the gas for burning combustible gas generated during blowing.

Furthermore, if necessary, as mentioned above, 0. While gas is supplied into the converter, stirring gas is introduced into the molten iron through the tuyere at the bottom of the converter or the lower part of the furnace wall.

The method of the present invention will be explained below based on the drawings showing its implementation state. FIG. 1 is a schematic diagram showing the initial state of blowing when melting molten steel containing Or by the method of the present invention.
l is a converter with a capacity of 250), and a plurality of tuyeres, that is, bottom blowing nozzles, are used to blow stirring gas into the bottom surface.
It is equipped with a, la...la. Then, 3 tons of hot metal was subjected to bath metal pretreatment on the hot metal tapped from the blast furnace.
It is charged into the converter I for decarburization and temperature raising. The pretreatment of the bath pig iron is carried out, for example, by injecting Mn ore into a tilting gutter installed to drop and inject the hot metal from the blast furnace taphole through the tap gutter, separating it from the slag, into the pig iron mixing car. This is carried out by desiliconization, followed by desulfurization and dephosphorization by adding soda ash inside the pig iron mixing car. It goes without saying that dephosphorization is not necessary for low-phosphorus hot metal. Then, approximately 40 to 50 Nv// is applied to the hot metal 3 from the main nozzle 2a of the lance 2 inserted into the converter from the furnace mouth 1b.
) for blowing with the supply amount of 0. Gas 4a't-blow;
Performs converter blowing. In addition, if necessary, the bottom nozzle la
, la .

During blowing, the tip of a chute 5 is positioned above the furnace mouth 1b of the converter l, and C is passed through the chute 51.
R ore is mainly charged into the converter l during the middle stage of blowing, but the C
In order to supply the heat required for reduction and melting of r ore, combustion O gas is supplied from sub nozzles 2b provided around the main nozzle 2a in an amount corresponding to the amount of Cr ore required for molten iron (see Figure 2). ) for blowing 0. In addition to the gas, it is blown onto the surface of the bath pig iron 3, and the converter generated gas, which is mainly composed of Co gas generated during blowing, is combusted. The waste gas produced by the combustion of the converter gas is treated by a waste gas treatment facility (not shown) connected above the furnace port 1b.

When producing molten steel containing Or as described above, the bath pig iron 3 charged into the converter 1 is subjected to a pre-bath pig iron treatment, and desulfurization, desiliconization and dephosphorization have already been carried out. Since the process is carried out in the converter, decarburization and temperature raising only need to be carried out in the converter l, making it possible to perform refining that hardly forms slag (slag minimum refining).
Therefore, since the combustion heat of the gas generated in the converter is transferred to the molten iron in a state where slag, which has a lower heat conduction efficiency than molten iron, is hardly formed, the heat transfer efficiency is significantly improved, and the Cr ore is transferred into the molten iron. The amount reduced and melted increases. Therefore, when introducing Cr ore into molten iron, it is possible to significantly improve the Cr yield.

Furthermore, when carrying out composite blowing* in which oxygen top blowing is performed while bottom blowing stirring is performed by blowing stirring gas from bottom blowing nozzles la, la...la, the molten iron is sufficiently stirred and as described above. Since almost no slag is formed, the heat transfer area of the combustion heat of the slag generated in the converter increases, the heat transfer efficiency further improves, and the amount of Cr ore reduced and melted into molten iron increases.

Therefore, when introducing Cr ore into molten iron, its Or
It becomes possible to further improve the yield.

In the above embodiment, the lance 2 for blowing gas into the blowing
from the sub-nozzle 2b for combustion. Although we decided to blow gas into the converter 1, it is also possible to insert a separate lance into the converter 1 from the lance for blowing gas into the blowing furnace, and blow gas for combustion from that lance. When blowing 0.2 gas, use 0.0 for blowing. The height of the lance relative to the molten iron is set higher than when blowing gas. The CO gas may be burned before the gas jet reaches the molten iron.

Hiko: In the above-mentioned embodiment, the stirring gas is supplied through the bottom blowing nozzles la and l.
Although it was decided to blow from a...1a, the same effect could be obtained by blowing from the siding at the bottom of the converter wall.n
It goes without saying that

Next, the method of the present invention will be explained in detail based on drawings showing its effects. Figure 2 shows the method for combustion. With respect to the gas supply amount, the corresponding molten iron rise temperature and Cr ore content t
This is a graph showing the results of a trial calculation. In the figure, the solid line, the broken line, and the dotted chain Im indicate the cases where the heat transfer efficiency of the combustion heat of the converter generated gas to the molten iron is 50%, 15%, and 100%, respectively. Note that this estimate is based on CO gas being combusted and CO
, combustion heat when it becomes gas t-30kca/ /Np1
l (30, specific heat of molten iron is 200kaa//t
on m C, and the step wb for ar ore Cr is 5
As is clear from the figure 0, which is taken as 0%, it can be seen that the heat transfer efficiency greatly affects the temperature rise of molten iron, that is, the amount of Cr ore that can be added. That is, if the heat transfer efficiency is high, the amount of Cr ore that can be added can be increased. Therefore, in the present invention, in order to improve the latent heat efficiency,
After performing hot metal preliminary treatment on the hot metal before charging into the converter, blowing (combined blowing as necessary) was performed on the bath pig iron.

Figure 3 is a graph showing the relationship between the amount of slag and the amount of OR yield. Section IIs shows the case where converter blowing was performed without bottom blowing stirring.

As is clear from the figure, the smaller the slag amount and the bottom blowing agitation, the better the OR yield. We were able to confirm the effectiveness of the method of the present invention, which performs blowing (combined blowing if necessary). Table 1 also shows that hot metal that has been subjected to desiliconization, dephosphorization, and desulfurization has a volume of i1:2.
50) When melting molten steel with an Or concentration of 3 by blowing in a converter of The heat transfer efficiency and CrfP retention t are compared between the two cases.

In addition, in the case of the method of the present invention, the blowing temperature is 0. The amount of gas injected was 3aNIF//)ton, and the amount for combustion was 0. The gas injection rate was 30 Nnf/), and the bottom blowing rate of the stirring gas was 0.8 Ns//).

1. Looking at the surface heat adhesion efficiency, when using the conventional method, it is at most 40
96, whereas when 11 blowings were performed by the method of the present invention, the improvement was 50 to 15%, and the Or
Regarding the yield, when using the conventional method, even when combined blowing is performed, the yield is at most 95%, whereas when combined blowing is performed using the method of the present invention, the yield is 98~100%.
The superior effect of the method of the present invention is t-1m.
I was able to m.

The method of the invention is applicable not only when adding Cr ore when melting the molten steel containing Or mentioned above, but also when adding Cr ore.
Of course, the present invention can also be applied to the case where various raw materials are added depending on the purpose when melting molten steel containing elements other than r. O at Ren
frjI11 containing r or N1! When doing so, w
E ore and ar ore are supplied to the gas tube furnace to convert the gas generated in the converter, in addition to the 0 mushroom gas for blowing, O for combustion, and the gas tube furnace to obtain the heat required for reducing and melting the raw material containing M1 oxide. This method improves the heat transfer efficiency of the combustion heat to the molten iron by combusting it in a furnace. This makes it possible to add a large amount of Fe ore, Or ore, or Ni [compounds] with a high yield of active ingredients, eliminating the need to use large amounts of expensive ferroalloy when tapping steel from a converter as in the past. , its benefits are extremely large.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the implementation state of the method of the present invention, FIG.
FIG. 3 is a graph showing the effect of the method of the present invention. 1... Converter 1a, la... la... Φ bottom blowing nozzle 2... Lance 2a... Main nozzle 2b...
Sub nozzle 3... Hot metal patent applicant Sumitomo Metal Industries Co., Ltd. Agent Patent attorney Noboru Kono Figure 1 Figure 3

Claims (1)

[Claims] 1. When melting molten steel in converter blowing, Pa ore,
In order to promote the reductive melting of raw materials containing C3r ore or N1 oxides, the hot bath pig iron is subjected to preliminary treatment including at least desiliconization, and then charged into the converter and heated to zero for blowing. Converter operating method 02, characterized by supplying combustion O and gas into the converter for burning combustible gas generated during blowing together with the gas;
When melting molten steel in converter blowing, Pa ore, Or
Ore is Nif! ! In order to promote the reduction bath melting of the raw materials containing oxides, bath pig iron that has undergone pre-treatment including at least desiliconization is charged into the converter, and combustibles generated during blowing together with 02 slag for blowing are charged. A converter operating method characterized by supplying 02 gas for burning gas into the converter, and introducing stirring gas into the molten iron from the bottom of the converter or the slats in the lower part of the furnace wall.