JPH11349385A - Closing material for tap hole of metal melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a closing material for a tap hole like a blast furnace mud material, having the same workability in production and force filling into a furnace as a conventional closing material, capable of stably securing hole depth and extremely prolonging a tapping time. SOLUTION: This closing material for a tap hole is obtained by adding 0.1-10 wt.% of an expandable graphite having properties of expanding its volume by tens to several hundreds times by heating and a tar and/or a phenolic resin as a binder during the blending of refractory raw materials. The closing material for a tap hole has functions of closing and restoring the occurrence of a gas blowing during tapping and a pheonomenon called a tunnel of extremely shortening a tapping time by an expansion pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plug material for a tap hole of a metal melting furnace such as an electric furnace or a blast furnace.

[0002]

2. Description of the Related Art The tapping material of a tap hole of a metal melting furnace, especially a tapping port of a blast furnace, becomes severer due to an increase in the size of the blast furnace and an increase in the amount of tapping by high-pressure operation. The required characteristics of the plugging material are not only conventional corrosion resistance and workability but also how to keep the hole depth of the tap hole deep and to supply the tap water for a long time.

[0003] Many studies have been made on improvement measures from this point. For example, Japanese Patent No. 2580204 and Japanese Patent No. 259222 disclose improvement measures.
As disclosed in Japanese Unexamined Patent Publication No. 4 and JP-A-10-36177, most of the approaches are based on combinations of chemical compositions.

On the other hand, as a measure for improving the structure of a tapping material for a taphole from the physical aspect, for example, Japanese Patent No. 2610280 discloses a technique for improving densification and corrosion resistance by utilizing a reaction between silicon iron nitride and clay. It has also been proposed to do this. But,
This is a densification using a sintering reaction, and the degree of improvement is only about 1 to 2%, which is not a test result in a confined space in an actual furnace, but rather the effect. Is not certain.

Furthermore, Japanese Patent Publication No. 7-115957 proposes to use a large amount of coarse aggregate of 5 to 10 mm and reduce the amount of binder to achieve densification. However, the structure at the time of filling and the structure of the hardened body formed thereafter do not always match, and it is important how the structure after filling is densified, which greatly affects the extension of tapping time. Will come.

Normally, a tapping material such as a mud material is used in an amount of 15 to 20% by weight in order to obtain the softness required for press-fitting.
Add about or more binders. Originally, a fine structure should be aimed at with a small amount of binder, but unavoidably, the workability is secured by increasing the amount of binder such as tar. The low-boiling substance is effective in lowering the viscosity of the tapping material for the tap hole, and facilitates the kneading operation in a low temperature range of room temperature to about 80 ° C., and at the same time, secures the press-in workability when using the actual furnace. As a result, a large amount of low-boiling components is used, resulting in the mud material becoming porous. Even if a mud material having a fine structure is ideal, the present situation is that it contains a considerable amount of a low boiling point component from the viewpoint of ensuring workability.

[0007] Most of the low-boiling-point liquid substances volatilize without remaining as carbon, so that the mud material is made porous, lowering the corrosion resistance and lowering the strength of the hot metal and molten slag. It suffers from erosion and abrasion, and consequently has a drawback that the durability is significantly reduced.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to ensure the softness, the fineness of the structure after filling and the stable securing of the hole depth, while maintaining the softness without impairing the workability at the time of manufacturing and filling. It is an object of the present invention to provide a tapping material for a tap hole which enables a drastic extension of time and has improved durability.

[0009]

The tapping material for a taphole according to the present invention contains 0.1 to 10% by weight of expanded graphite in a refractory raw material mixture, and tar and / or phenol resin is added as a binder. It is characterized by the following.

The expanded graphite used in the present invention is widely known as a raw material for producing graphite films and graphite sheets. Generally, it is produced by subjecting natural scale graphite to a wet oxidation treatment with sulfuric acid and nitric acid or halogen peroxide, etc. In addition, it is also introduced in Japanese Patent Publication No. 1-49641. However, the production method is not particularly limited, and it is a graphite material having a property that its volume expands by several tens to several hundreds by heating.

This expanded graphite has a great feature in that it begins to expand at about 200 ° C. The amount used is 0.1
If the amount is less than 10% by weight, a densification effect due to the expansion of graphite cannot be obtained. If the amount exceeds 10% by weight, a large amount of a binder is required in order to secure workability, and the corrosion resistance is deteriorated.

Usually, a binder for a tap hole is added to a binder of about 15 to 20% by weight or more in order to obtain softness required for press-fitting.

As the binder, a tar or phenol resin having a relatively low boiling point component and a large residual carbon content is used. A tapping material for a taphole using a tar or phenol resin as a binder is usually heated to about 60 to 70 ° C, kneaded and manufactured in a warm state. When it is used in a blast furnace, it is heated to the same degree and press-fitted. Heating and using a little, without the help of low-boiling substances,
This is to reduce the viscosity and secure workability.

[0014] The tapping material of the present invention does not require any change in the press-in operation itself, and does not require any reduction in the amount of the binder, and receives heat after the press-in operation to reduce the expansion pressure of the expanded graphite. Use it to transform into a dense organization.

As the refractory raw material constituting the aggregate and the fine powder portion of the mud material of the present invention, the refractory raw material used in the conventional mud material can be used, and there is no particular limitation. For example, high alumina raw materials such as fused alumina, sintered alumina, and bauxite; siliceous raw materials such as rhoite and clay chamotte; non-oxide raw materials such as silicon carbide, silicon nitride and silicon iron nitride; coke; , Pitch, scale-like graphite, etc., metal powders such as silicon, aluminum, ferrosilicon, etc., and clay-like materials such as kaolin, sericite, bentonite, etc., and these are used in appropriate combination. .

The binder is preferably one having a high residual carbon, but it does not limit the present invention, and any of coal-based or petroleum-based tar can be used. It may be diluted with creosote oil or anthracene oil for viscosity adjustment. The phenolic resin may be either a novolak type or a resol type, and may be used alone or in combination with tar.

After filling and closing the taphole, the mud material gradually hardens and forms a hardened body over time due to heat reception, but the hardening process is complicated. Tar or the like as a binder has thermoplasticity and is further thermally softened once by heat reception, while low-boiling components contained in the tar and the like are
It is considered that it is volatilized by the heat reception, the liquid phase component gradually decreases, and is hardened (solidified). When a phenolic resin is used as a binder, curing is accelerated by the polymerization action of the resin, but basically follows the same solidification process. In this process, and under a constraint such as in the pore, by giving a strong expanding action, it is considered that the tissue is rearranged and densified. This densification makes it possible to extend the tapping time.

Further, the tapping material for a taphole of the present invention also has a function of closing and repairing a phenomenon called a horizontal hole in which gas is blown during tapping or an extremely short tapping time is caused by expansion pressure.

In order to exhibit this function as a tapping material for a taphole, it is not sufficient to simply use a substance that expands. It is most important that the timing of the generation of the expansion pressure matches the thermal softening of the binder. Conversely, the solidification rate and imbalance of the binder promotes porosity and induces large cracks. In this regard, the expanded graphite shows excellent matching with the solidification rate of tar or phenol resin as a binder. Furthermore, this expanded graphite not only generates an expansion pressure but also remains in the tissue and has excellent slag resistance as a graphite substance, and further promotes high durability as a tapping material for tapholes.

The tapping material for tapholes of the present invention contains expanded graphite, and has the same composition and usage as ordinary mud materials and tapping material for tapholes except that tar or phenol resin is used as a binder. And various raw materials can be used. In addition, it can be manufactured according to a known technique.

The addition of expanded graphite has the function of improving the ordinary plugging material for tapholes, and additionally does not impair the original function of the base material due to the effect of densification under constraint. It achieves significant enhancements.

The tapping material for tapholes of the present invention has a remarkable expansion property upon heating, and is filled in a hole and restricted as in the case of being used in tapholes of blast furnaces. It is characterized in that a good tissue is formed only when heated in the above. When heated in an unconstrained state, a remarkable expansion performance exhibits an adverse effect, resulting in an extremely porous body.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to examples in which the present invention is applied to a mud material for a blast furnace taphole.

Table 1 shows the contents of expanded graphite and binder in the tapping material for tapping holes according to the examples of the present invention and the characteristics thereof together with comparative examples. The ordinary mud material shown in comparative example 1 was used as a base. Next, the addition effect was confirmed by adding and replacing the alumina fine powder constituting the fine powder portion with expanded graphite.

The mud material used as a base (Comparative Example 1)
Is a commonly used raw material composition in which rhoite and bauxite are used as the main aggregate, and the fine powder portion is made of silicon carbide, silicon iron nitride, fused alumina, clay, silicon, carbonaceous raw material and the like.

Although it is difficult to reproduce and accurately evaluate the use condition of the actual furnace using the tapping material for a taphole of the present invention in a laboratory, it is necessary to reproduce the use condition of the actual furnace as follows. An evaluation test was performed.

One end is sealed, inner diameter 120 mm, outer diameter 180
mm, 500mm long alumina-graphite tube,
After filling a predetermined amount of the mud material, an alumina castable was poured as a lid. The castable was dried at 110 ° C. for 24 hours in order to express the strength and firmly close the lid. In order to prevent danger such as explosion during the mud material heating experiment, a vent hole having an inner diameter of 10 mm was provided. As described above, after the mud material was placed in the restrained state, heating was performed at 1200 ° C. for 3 hours (the temperature rising rate was 200 ° C./hr). After cooling to room temperature, the central part was cut, the cross section was observed, and then the porosity of the mud material was measured for the purpose of quantifying the degree of densification of the structure.

[0028]

[Table 1] The Marshall test value is a softness at which a value of 15 to 25 Kg / cm ² can be used for performing a proper filling press-in operation.

In the table, ◎: good without cracks, Δ: fine cracks,
Δ indicates that there are a few cracks or voids (hollows), and X indicates that there are many large cracks or voids (hollows).

The filling press-fit test was conducted by placing a mud material maintained at 60 ° C. into a mold having an inlet diameter of 70 mm and an outlet diameter of 20 mm, and using a marshall tester to pressurize and extrude at a moving speed of 50 mm / min. The maximum load was measured.
The value measured by the Marshall tester is an index of the filling performance. If the value exceeds 25 Kg / cm ² , it becomes too hard and normal press-fit cannot be performed. Conversely, if it is less than 15 kg / cm ^2, it is too soft and drastically sags, impairing the handling properties of the mud material,
A satisfactory cured product cannot be obtained.

As shown in Example 1 of the same table, the expanded graphite exhibited a densifying effect when its amount was 0.1% by weight.
With less than 0.05% by weight (Comparative Example 2), a sufficient effect cannot be obtained. On the other hand, as the amount of expanded graphite is increased, the amount of binder required to obtain proper press-in workability gradually increases, and this is thought to be due to an increase in low-boiling volatile components, but the densification effect is slightly reduced. I do. Therefore, the upper limit of the amount added is 10% by weight. Exceeding this, in Comparative Example 3 in which 15% by weight was added, the amount of binder was remarkably increased and the test was stopped because an appropriate Marshall test value could not be obtained. In response to such laboratory evaluation result of the above, it was carried out practical test at 4000m ^3-class large-scale blast furnace. In this practical test, n = 40 to 50 press-fits were performed for several kinds of materials for about one week for each material.

In the conventional product (Comparative Example 1), the tapping time was 12
Although it was 5 to 160 minutes and the average was 145 minutes, in Example 3, the tapping time was 230 to 275 minutes and the average was 260 minutes, indicating a remarkable improvement effect. Hole depth is 200 more than conventional products
It was stable at a place that is ~ 300 mm longer. Furthermore, no side-hole phenomenon was observed during the test.

In the other examples, as shown in the practical test results, the tapping time was significantly extended,
Excellent results were obtained.

As described above, similar to the results in the laboratory,
When the expanded graphite is blended in the range of 0.1 to 10% by weight, a stable hole depth is secured (100 to 100% more than the comparative example 1 which is a conventional product).
Remarkably long tapping (1.3 to 1.8 mm)
Times).

[0035]

According to the plugging material for a taphole of the present invention, further higher service life can be achieved from a completely different viewpoint from the conventional high service life technology combining various refractory raw materials. That is, densification is achieved by the physical action of expanded graphite,
In the hole filled with press-fitting, it is possible to easily obtain a systematically excellent hardened body, prevent phenomena such as side holes commonly known, and secure a stable hole depth and greatly increase tapping time. Possible extension.

Claims (1)

[Claims] 1. An expanded graphite is added to a refractory raw material in an amount of 0.1%.
-10% by weight, and tar and / or
Or a closing material for a tap hole of a metal melting furnace to which a phenol resin is added.