JPH02205608A - Method for protecting furnace bottom part in blast furnace - Google Patents

Abstract

PURPOSE:To quickly and efficiently protect locally damaged part by blowing mixed powder material of powdery TiO2-containing material and powdery iron-containing material from a tuyere at near this damaged part position under the specific condition at the time of detecting the local damage in furnace bottom. CONSTITUTION:At the time of detecting the locally damaged part at the furnace bottom with measured value by a thermometer embedded in the bottom part of a blast furnace, the mixed powder material of the powdery TiO2-containing material and the powdery iron-containing material is blown from the tuyere at near the detected damaged part position. Then, in the case of using T.Ti and T.Fe for Ti and Fe concns. (wt.%) in the mixed powder material, respectively, the mixed powder material is blended under the condition satisfying the inequality 6>=T.Ti/(T.Ti+T.Fe)X100>=0.3. By this method, TiC and TiN stuck to coke is reduced and a large quantity of the mixed powder material can be blown into and also Ti reaching the furnace bottom is increased and the local damaged part in the furnace bottom is quickly and efficiently protected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for quickly and efficiently protecting a localized horizontally damaged portion of a blast furnace bottom.

[Conventional technology]

The biggest factor that determines the lifespan of a blast furnace is damage to the bottom of the furnace. For this purpose, sintered ore has traditionally been produced by adding a TiO2 source such as iron sand to the sintering raw material.

A measure to protect the furnace bottom was to charge the sintered ore into a blast furnace and form titanium bears at the bottom of the furnace.

However, in this method, it is necessary to form titanium bears over the entire area of the hearth bottom, even for a locally damaged part 1 of the hearth bottom as schematically shown in FIG. Because a large amount of slag is charged into the blast furnace, operational problems such as poor air permeability and poor slag discharge often occur. In addition, in FIG. 2, 2 shows the hearth bottom brick part, and 3 shows the hearth bottom profile at the time of furnace construction.

To solve such problems, 2 For example, JP-A-60-5
The method of injecting powdered titanium iron ore into the grains near the localized damage position proposed in Japanese Patent Application No. 6004 and Japanese Patent Application Laid-Open No. 60-228611 is effective.

[Problem to be solved by the invention]

The present invention further improves the method proposed in JP-A No. 60-56004 and JP-A No. 60-228611, and effectively allows the Ti source injected from one tuyere to drip onto the bottom of the furnace. The present invention aims to provide a method for quickly and efficiently protecting local horizontal damage at the bottom of a blast furnace.

[Means to solve the problem]

Local damage to the bottom of the blast furnace is detected based on the temperature measured by a thermometer buried at the bottom of the blast furnace, and a powdered TiO2 source is injected from the tuyere near the detected local damage location to protect the horizontally damaged area. In the method 2 of the present invention, powdered TiO2
The method is characterized in that a mixed powder obtained by blending a containing substance and a powdered iron-containing substance under conditions that satisfy the following formula (1) is blown into the pores.

6≧T, Ti/(T, Ti+T, Fe)X100≧0.
3--(1) Here, T, Ti, T, and Fe are the concentrations (wt%) of Ti and Fe in the mixed powder, respectively.
It is.

[Effect]

The present inventors obtained the following findings from repeated experimental studies. That is, as shown in FIG. 3, when a TiO□ source 5 such as powdered titanium iron ore is blown along with hot air 4 from the tuyere 6 of an experimental furnace filled with coke, such as a blast furnace, the coke is TiO in raceway 7, which is the combustion area.
The □ source is melted, and the melt 8 reacts with coke to reduce iron oxide and TiO□. At this time, TiC and TiN are produced, and Ti is also dissolved in the molten iron produced by reducing iron oxide. The generated TiC and TiN all adhere to the coke, and as a result, do not drip to the lower part of the furnace.

The Ti dissolved in the molten iron drips into the lower part of the furnace, and the - portion becomes TiC'PTiN during the dripping process and adheres to the coke. In Figure 3, 9 is a T with coke attached.
ic, which schematically shows TiN. In this way, only a portion of the Ti source injected from the two tuyeres drips onto the bottom of the furnace.

The dropping Ti carrier is molten iron. In addition, in FIG. 3, 10 is molten iron in which Ti is dissolved.

11 is a slag layer, 12 is a molten iron layer, and 13 is a titanium bare.

Therefore, like the prior art of the above-mentioned publication.

When titanium iron ore with high T, Ti/(T, Ti+T, Fe) is injected, there is less molten iron that serves as a carrier for Ti, so less Ti reaches the bottom of the furnace, and moreover, a large amount of TiC and TiN adhering to the coke, which obstructs liquid permeability, resulting in a double problem in that the amount of titanium iron ore injected must be limited. On the other hand, when a mixed powder of TiO□-containing ore and iron ore is injected from the tuyere according to the present invention, less TiC and TiN adhere to the coke, and a large amount of the mixed powder can be injected. This is because the amount of Ti that reaches the bottom of the furnace increases.

It has become clear that locally damaged areas at the hearth bottom can be protected efficiently and quickly.

When the mixed powder is actually blown into the blast furnace,
As shown in Figure 1, there was a tendency for the protection of the furnace bottom to be delayed due to the presence of the mixed powder. Therefore, when blowing a powdered TiO□ source from the tuyere near the locally damaged location on the furnace bottom to protect the horizontally damaged area, powdered TiO2-containing ore and iron ore should be mixed under the conditions of equation (1). Simply blow the powder mixed in through the tuyere.

Next, the effects of the method of the present invention will be shown using specific examples.

Example A mixed powder of a TiO2-containing material and an iron-containing material was injected into a 2150 m3 blast furnace having 26 tuyeres under the conditions shown in Table 1 through two adjacent tuyeres 9 to a position directly below the tuyeres. The time T required for the reading of the embedded thermometer to drop by 3°C was measured. As the Ti1t-containing substance, iron sand and high titanium slag having the composition shown in Table 2 were used. The iron-containing material is powdered iron ore (bellet feed). In Examples 1 to 4 and Comparative Example 1, iron sand and iron ore Table 2 Particle size and composition of the injected material As shown in Table 1, T, Ti/(T, Ti+T, Fe
) In Examples 1 to 5 under the condition that X100 is 6 to 0.3.

Mixed powder can be continuously blown at 10kg/T.

Titanium bears were formed at the bottom of the furnace in about one day, and the temperature at the bottom of the furnace immediately below the tuyere decreased by 3°C. In Comparative Example 1, the formation of titanium bears was delayed compared to Examples 1 to 4, and the bottom temperature of the furnace reached 3.5% in 35 hours.
°C decreased. On the other hand, when the iron sand of Comparative Example 2 was blown, a phenomenon in which molten material accumulated in the raceway was observed 20 hours after the start of blowing, so the blowing amount was reduced from 10 to 4 kg/T. As a result, it took a total of 49 hours to lower the furnace bottom temperature by 3°C.

4. Brief explanation of the diagram Figure 1 shows that the furnace bottom temperature directly below the tuyere into which the Ti source is injected is 3°C.
The time T required for the drop to decrease and the Ti source T, Ti/(T, T
A diagram showing the relationship between i+T, Fe)

FIG. 3 is a schematic cross-sectional view schematically showing the reduction behavior of the Ti source blown into the lining.

■... Locally damaged part of the hearth bottom, 2... Hearth bottom bricks 3.
- Hearth bottom profile during furnace construction, 4. Hot air.

5. Ti source, 6. Ume, 7. Racew,
A, 8...Ti source melt, 9...TiC, TiN with coke attached, 10...molten iron with dissolved Ti, 11...slag, 12...molten iron, 13...titanium bear diagram

Claims (1)

[Claims] Local damage at the bottom of the blast furnace is detected based on the temperature measured by a thermometer buried in the bottom of the blast furnace, and a powdered TiO_2 source is injected from the tuyere near the position of the detected local damage. A method for protecting a horizontally damaged part is characterized by blowing a mixed powder formed by blending a powdered TiO_2-containing substance and a powdered iron-containing substance under conditions that satisfy the following formula (1) from the tuyere. A method for protecting the bottom of a blast furnace in which 6≧T. Ti/(T.Ti+T.Fe)×100≧0.
3...(1) Here, T. Ti and T. Fe is the concentration of Ti and Fe in the mixed powder (wt%), respectively.
).