JPS5912620B2 - Blast furnace tap hole blocking material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a material for plugging a blast furnace tap hole (hereinafter referred to as a plugging material).

), the purpose of which is to provide a plugging material with improved workability, hardening and sintering properties, and corrosion resistance.

The plugging material for the blast furnace is required to have the following properties in terms of workability, hardening and sintering properties, corrosion resistance, etc.

(a) In terms of workability, the material must have enough plasticity to allow easy filling of the plugging material into the blast furnace tap hole with a mud gun, making it easy to open the tap hole, and (b) hardening. Sinterability is determined by the completion of hardening and sintering to maintain the plugging after the plugging material is filled into the blast furnace tap hole until the next opening. (c) Corrosion resistance is determined by the extraction of hot metal and slag. (a) In addition, the plugging material is deposited in the furnace with a good yield after being filled into the taphole. Hot metal is sintered and released from deep inside the furnace.
The taphole should have a deep part from which slag can be extracted.

High-pressure operation is common in recent large blast furnaces, production capacity has increased, and the amount of iron tapped per cycle and the rate of tapping have increased significantly.Therefore, corrosion resistance as a plugging material is important and stable blast furnaces. Affects operations.

Large blast furnaces usually have a plurality of tap holes, which are generally used alternately, and therefore the plugging material is usually used in a sufficiently sintered state.

However, due to problems with tapping and problems with the mud gun opening machine, it is often necessary to perform the next tap without giving enough time to sinter the plugging material from the same tap hole, resulting in stable operation of the blast furnace. Therefore, the so-called early strength, which means that the hardening and sintering time of the plugging material is short, is also an important element of the plugging material.

In addition, it is important to ensure the depth of the tap hole by using plugging materials in order to protect the bottom bricks of blast furnaces and to stabilize operations (reducing wind pressure fluctuations due to the reduction of pig iron slag).

Conventional plugging materials include refractory aggregates such as chamotte, alumina, Rouseki, and zircon silicon carbide, while clay and Rouseki powder are used as sintering materials, and tar, pitch, and heavy oil-based binders take about 60 minutes or more to develop strength. Therefore, it was necessary to use a large amount of clay and Rouseki powder for the purpose of imparting sinterability.

Even so, the early strength of the plugging material was not sufficient, and stable operation in front of the furnace was often threatened by green blowing due to insufficient hardening and sintering of the plugging material.

In addition, to improve the corrosion resistance of the plugging material, high-grade refractory materials such as alumina and silicon carbide are used as aggregates, but as mentioned above, many low-melting products such as clay and Rouseki powder are added, so these clay Rouseki powders are added. Due to selective erosion of powder, etc., it has not been able to fully demonstrate the characteristics of other high-grade refractory materials.

Tar-based binders have the disadvantage that they do not develop strength quickly after being filled with plugging material in the tap hole, as well as problems with the working environment due to the large amount of black smoke generated from tar when plugging, and harmful substances contained in the coolant. There were safety and health issues during work.

Therefore, various resins such as phenol resins have been tried to solve these problems.

It was thought that the early strength of this resin could be significantly shortened compared to that of cool resin, depending on the amount of curing agent added.

However, when the plugging material is filled into the mud gun, the resin may harden in the mud gun due to the radiant heat of the blast furnace, and during filling, it may cause seizure between the plugging material and the taphole lining in the taphole. There were many problems such as the mud gun's suppression becoming overloaded and making smooth filling difficult.

Therefore, in order to reduce the hardening agent and impart sinterability similar to a tar-based binder, and furthermore to develop plasticity as a plugging material, it is necessary to add a large amount of clay and Rouseki powder. It was also the cause of a decrease in corrosion resistance.

Furthermore, no proposals have been made regarding plugging materials for the purpose of increasing the depth of the tap hole.

In view of the above-mentioned circumstances, the present invention has conducted various studies and examinations on the various drawbacks of conventional plugging materials, and has discovered the application of ultrafine amorphous silica powder, which will be detailed below, and has developed a new method for plugging materials that improves the tap hole depth characteristics and improves blast furnace depth characteristics. The workability, sinterability, and corrosion resistance of the tap hole plug material were advantageously solved.

That is, the present invention adds a carbonaceous raw material to one or more refractory raw materials such as chamotte, alumina, Rouseki, zircon, and silicon carbide, and adds 1 to 10 parts by weight of ultrafine amorphous silica powder with an average particle size of 3 μ or less. It is a plugging material for blast furnace tap holes made by adding and kneading an organic binder.

As the refractory raw material used in the present invention, one or a mixture of two or more of ordinary chamotte, alumina, Rouseki, zircon, silicon carbide, etc. is used.

Carbonaceous raw materials are added to this to prevent the intrusion of hot metal and slag.

The carbonaceous raw materials include scaly graphite, earthy graphite, electrode scraps, coke, pinch, carbon black, carbon fiber, etc. The amount used is not particularly limited, but is 5 to 30 parts by weight based on the refractory raw material. The range of is optimal.

If the amount is less than 5 parts by weight, the effect of preventing intrusion of hot metal and slag is insufficient, and if it is more than 30 parts by weight, the intrusion prevention is sufficient, but workability and sinterability are reduced.

The reason for this is that carbonaceous raw materials originally have poor wettability and sinterability.

Furthermore, the amorphous silica ultrafine powder used in the present invention is a by-product during the production of white carbon, metal silicon, or silicon alloy, and is collected dust known as silica flour or amorphous silica ultrafine powder. The main component is amorphous silica, and its basic particles are 0.5 mm according to a scanning electron microscope. It is an ultrafine powder of ~0.01μ and has a high surface energy, and when actually used, the amorphous silica ultrafine powder has a certain degree of agglomeration and appears to be particles, that is, secondary particles are considerably larger than the basic particles. .

This ultrafine amorphous silica powder has a spherical shape and an extremely small particle size.

Among them, those with an average particle size of 3μ or less in the rosin lambda diagram are extremely effective in expressing the plasticity, also expressed as the so-called stiffness, characteristic of occluding materials when used within a certain range as occluding materials. The workability of the tap hole has been significantly improved, and the depth of the tap hole into the furnace has been significantly improved.

If the depth of the tap hole is shallow, the flow of hot metal slag in the tap hole during tapping will be turbulent, and the lowering of the liquid level in the furnace due to tapping will accelerate gas entrainment and cause physical blockage. This is a major cause of shortening the service life of the metal, and it also leaves behind pig iron slag inside the furnace, which causes wind pressure fluctuations and makes the furnace condition unstable, and ultimately accelerates the wear and tear of the furnace bottom bricks.

When the plugging material is filled into the tap hole, the plasticity caused by the addition of the ultrafine powder improves the adhesion to the old plug and the upper part of the furnace, making it possible to extend the depth of the tap hole.

As described above, the inventors were able to achieve a number of improvements by applying ultrafine silica powder with an average particle size of 3 μm or less as a plugging material for blast furnace tap holes.

That is, when observing the properties of the above-mentioned ultrafine silica powder at high temperatures using a sample after firing, the powder maintains its spherical shape and remains amorphous silica at temperatures below 600°C.

On the other hand, at a temperature of 600°C or higher, the secondary particles exhibit sintering and a network structure in terms of microstructure.

Adding the ultrafine powder to the occluding material promotes densification of the tissue due to its ultrafine powder properties, and also densely fills the matrix portion of the occluding material.

The ultrafine powder improves the sinterability of the plugging material by bonding the aggregates through mesh sintering as described above from the temperature reached at around 600° C. immediately after the plugging material is filled into the tap hole.

12
Ultrafine silica powder reacts with carbon from the carbonaceous raw material and binder in the temperature range from 00℃ to approximately 1500℃, the temperature during iron tapping, to generate β-8iC in the matrix, and strengthen the matrix by β-8iC bonds. That's what I do.

As described above, along with the matrix reinforcement of the reaction product of ultrafine silica powder, the reaction product is generated in the pores of the plugging material,
By promoting the formation of fine pores, it is possible to create a plugging material that is resistant to the intrusion of hot metal slag and erosion.

The reason why the average particle size of the ultrafine silica powder is limited to 3μ or less is that if it is larger than that, the ultrafine silica powder will not be sufficiently dispersed between the aggregates, the plasticity development effect will be small, and the workability will not be improved much and the sintering will be difficult. The resultant effect is also insufficient.

In addition, at high temperatures, unreacted ultrafine silica powder remains, making it difficult to expect much improvement in corrosion resistance.

Furthermore, if the amount of ultrafine silica powder added is less than 1 part by weight, the dispersion in the matrix will be insufficient and the characteristics of the plugging material, ie, workability, sinterability, and corrosion resistance will not be improved.

On the other hand, if the amount of ultrafine silica powder exceeds 10 parts by weight, the amount of binder increases due to its fine powder nature, causing the structure to become porous at high temperatures, and the amount of unreacted ultrafine silica powder remaining increases, resulting in a decrease in corrosion resistance. Because it guides you.

The organic binder used is coal tar, pitch, tall oil, phenol resin, furan resin, etc.

Examples will be described below.

Example 1 The tar-bonded plugging material added and kneaded in the proportions shown in Table 1 was reduced and fired, and its temperature and bending strength were measured. As is clear from Figure 1, 3 parts by weight of ultrafine silica powder and Products A-2 and A-3 of the present invention containing 7 parts by weight have a temperature of 500 to 600'C due to the network structure of the ultrafine silica powder.
The strength suddenly improves, reaching β-8iC at around 1,200℃.
This produced higher strength than conventional product A and Hieda products A-1 and A-4.

Conventional product A to which ultrafine silica powder was not added did not show much improvement in strength over the entire temperature range.

Further, comparative product A-1, in which the amount of ultrafine silica powder added deviated from the ratio of the present invention, was not significantly different from conventional product A, while comparative product A-4 showed a significant decrease in strength from around 1200'C.

Furthermore, when the plugging material described above was filled into the tap hole, as shown in Table 3, products A-2 and A-3 of the present invention had particularly good workability, and were quickly hardened and sintered after filling. , the corrosion resistance is good, and the tapping depth is increased, and the expansion of the tap hole is small from the initial stage to the final stage, making it possible to increase the amount of tapped iron and achieve stable tapping.

Example 1 Example 2 Resin-bonded plugging materials having the compounding ratios shown in Table 2 were measured in the same manner as in Example 1. As shown in Figure 2, 4 parts by weight and 7 parts by weight of ultrafine silica powder were added. Invention products B-2 and B-3 also have a 500 to 6
The strength improved from 00°C and had high strength even at 1200''C.

Conventional product B to which ultrafine silica powder was not added showed no improvement in strength over the entire temperature range.

Comparative product B-1, in which the amount of ultrafine silica powder added deviates from the range of the present invention, is the same as conventional product B, and comparative product B-4 has a content of 1200.
The strength decreased rapidly from around ℃.

When the plugging material was filled into the tap hole, as shown in Table 3, the present invention products B-2 and B-3 had the conventional product B1 gravity B-1,
Compared to B-4, it has better workability, hardens and sinters quickly after filling, and has a larger tapping depth, with no expansion of the tap hole from the beginning to the end of tapping, and the amount of tapped iron is increased. This resulted in an increase in the amount of iron and stable tapping.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the hot bending strength of the plugging material and temperature at the mixing ratio of Example 1, and Figure 2 is a diagram showing the relationship between the hot bending strength of the plugging material and temperature at the mixing ratio of Example 2. be.

Claims (1)

[Claims] 1 Add a carbonaceous raw material to one or more refractory raw materials such as chamotte, alumina, Rouseki, zircon, and silicon carbide, and add ultrafine amorphous silica powder with an average particle size of 3 μ or less 1
A plugging material for a blast furnace tap hole, which is obtained by adding and kneading ~10 parts by weight and an organic binder.