JP2968258B1 - High spalling resistant carbon-containing refractory and method for producing the same - Google Patents

Abstract

[PROBLEMS] By using a binder having a low residual ratio and a refractory raw material having a fixed particle size in combination, high filling,
To provide a carbon-containing refractory which can obtain a high-density refractory structure and maintain a low carbon bond strength, and is excellent in damage resistance and corrosion resistance. SOLUTION: In a carbon-containing refractory material containing a refractory raw material, a carbon raw material, and a binder, the refractory raw material includes particles of 0.3 mm or less in an amount of 30% by weight based on 100% by weight of the entire refractory raw material. A carbon-containing refractory comprising 20 to 90% by weight of particles having a particle size of 1 mm or more and a binder content of 30% by weight or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a carbon-containing refractory and a method for producing the same, and more particularly, to a carbon-containing refractory having excellent spalling resistance and corrosion resistance and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, refractories containing a carbon material such as graphite exhibit high durability due to the properties of carbon, such as high thermal conductivity and the property of being hardly wetted by molten slag. Widely used. However, in recent years, the use conditions of this type of refractory have become more severe with the sophistication of metal products represented by higher performance of steel products.
It is desired to further improve the durability of carbon-containing refractories. The refractory properties required for improving the durability of the carbon-containing refractory include spalling resistance, corrosion resistance, oxidation resistance, abrasion resistance and the like.

[0003] Among these refractory properties, spalling damage is regarded as a problem to be solved most as a phenomenon that seriously reduces the serviceability of the refractory. In considering the spalling damage, that is, the refractory peeling phenomenon due to crack generation and extension, mechanical properties derived from the connective structure of the refractory are important.

[0004] With respect to the formation of the refractory connective structure, the technique of using the binder is very important. In the case of a carbon-containing refractory, no chemical bond is formed between the refractory aggregate and the carbon raw material. Therefore, a binder is indispensable for forming a refractory structure, and an organic binder such as a phenol resin or pitch is generally used. These organic binders are added in a liquid state in a mixing or kneading operation, are coated on the surface of the refractory raw material, and form the refractory structure by bonding the refractory raw materials through molding and drying operations.

The organic binder present in the carbon-containing refractory structure has a fixed carbon content remaining as carbon when the refractory is heated, and thereafter forms a refractory structure as a carbon bond to greatly enhance the characteristics of the refractory. Will rule. Until now, application of various organic binders has been studied mainly for the purpose of improving spalling resistance. For example, Japanese Unexamined Patent Publication No. 5-301759 discloses a method of using a resin binder having a high residual carbon ratio or a residual ratio (hereinafter, simply referred to as “residual ratio”) for refractories. It has been shown that high strength can be obtained.

Attempts have also been made to improve the spalling resistance by introducing pitch-derived crystalline carbon having excellent spalling resistance into the refractory structure by adding pitch powder having a high residual ratio. I have. For example, Japanese Patent Publication No. 57-27867 and Japanese Patent Application Laid-Open No. 2-268953 disclose a technique for improving the intermediate strength by adding a high softening point pitch having a high residual ratio to a carbon-containing refractory or a pitch treated at a high temperature. It has been disclosed. In addition, JP-A-5-270889 and JP-A-2592219 disclose a carbon bond by adding a mesophase pitch having a high residual ratio to a carbon-containing refractory or a highly dispersible pitch having a softening temperature in a certain range. Methods for enhancing are disclosed.

[0007] These current techniques are intended to improve the spalling resistance of a refractory by forming a carbon bond having more excellent spalling resistance, but the basis of the idea is as follows. A high-strength refractory is obtained by bonding the refractory aggregate and the carbon raw material with a carbon bond as dense as possible using an organic binder with the highest possible residual ratio, and the bonded carbon is crystalline with superior spalling resistance It is intended to improve the spalling resistance of the refractory by being formed of carbon.

[0008] However, looking at the relationship between spalling damage and the mechanical properties of the refractory, increasing the strength of the refractory may not necessarily improve spalling resistance. As for the relationship between spalling damage and mechanical properties of a material, it is known that a certain relational expression holds for crack initiation and extension by thermal shock, and thermal shock fracture resistance coefficient ( R, R ', R'') and thermal shock damage resistance coefficients (R''', R '''') have been theoretically derived (Ceramics, 12, No. 2, 150-55 ( 1977)).

In general, when dealing with the problem of thermal stress destruction of a refractory, it is considered that the generated thermal stress when subjected to a thermal shock is determined by the ambient temperature conditions, the heat transfer conditions of the refractory, and the mechanical property values. The existence of cracks will be discussed depending on whether the internal thermal stress exceeds the fracture strength of the refractory. What is being discussed in this case is the "generation" of cracks, and the thermal shock fracture resistance (hereinafter, simply referred to as "fracture resistance") coefficient among the theoretical resistance coefficients is an index indicating the resistance. Have been. That is, the fracture resistance coefficient is an index indicating the resistance to crack generation, and the larger the value, the more difficult the crack generation.

When the strength of a material is S and the elastic modulus is E, it is known that the fracture resistance coefficient is proportional to S / E. By increasing the strength of the refractory, the fracture resistance of the refractory is improved. An approach is taken. The above-mentioned use of a high-residual binder and strengthening of a refractory by carbon bond reinforcement are all carried out for the purpose of improving this fracture resistance, that is, the resistance to the occurrence of cracks.

On the other hand, the spalling damage of a refractory may be determined by the extent to which the generated crack itself does not lead to catastrophic damage, but rather to the extent to which the generated crack extends. A thermal shock damage resistance (hereinafter, simply referred to as “damage resistance”) coefficient is known as an index indicating resistance to the extension of the crack. That is, the damage resistance coefficient is an index indicating the resistance to crack extension, and the larger the value, the more difficult it is for crack extension to occur.

Since the damage resistance coefficient is proportional to E / S ² ,
By increasing the strength of the refractory, the damage resistance is reduced. Change in mar resistance becomes a reducing in S ² with respect to the increase in the material strength S, it is clear that exponentially decreases significantly.

As described above, spalling damage usually referred to includes two phenomena of crack initiation and crack extension. When the mechanical properties of the refractory are changed, the fracture resistance and the damage resistance show opposite trends. Therefore, the above-described carbon bond strengthening technique has resulted in reducing damage resistance while improving fracture resistance.

[0014] The spalling damage that occurs in the carbon-containing refractory actually used in the actual machine is observed as an exfoliation phenomenon of the refractory, but cracking and extension occur until the spallation occurs. It has gone through both stages. When the fracture resistance is improved, cracks are less likely to occur, but on the other hand, the damage resistance is reduced and the cracks once formed become easier to spread, so the spalling resistance as a whole is not much improved, and in some cases the durability is poor. Sometimes it gets worse. Therefore, in order to reduce spalling damage in actual use, it is necessary to improve both the fracture resistance and the damage resistance, and it is particularly important to increase the damage resistance.

[0015] In addition, several application examples have been disclosed as techniques for using an organic substance having a low residual ratio as a binder for a carbon-containing refractory. For example, Japanese Patent Application Laid-Open No. 52-32912 discloses a method of using a hexavalent polyol such as sorbitol, mannitol, polysorbitol and the like. A method of uniformly mixing with an aqueous solution or suspension of a non-aromatic organic polymer compound such as acrylolate, polyvinyl, polyalcohol, methylcellulose and the like is disclosed.

However, these methods do not provide sufficient moldability and require two-stage molding or have a problem that the obtained refractory is inferior in corrosion resistance. Not enough technology. In addition, JP-A-9
Japanese Patent No. 221370 discloses a method in which a saccharified starch or a reduced saccharified starch is used as a binder together with a solvent. According to this method, there is no problem in moldability, and it is shown that high corrosion resistance can be obtained.

However, in this method, since the residual ratio of the binder is low, the contact between the refractory aggregates increases at a high temperature, and sintering of the refractory aggregates occurs due to long-time heating at a high temperature, and the bonding point is reduced. Increase. As a result, the strength and the elastic modulus increase and the damage resistance decreases, and there is a problem in spalling resistance assuming use of an actual machine.

On the other hand, the low-residual organic binder used in the present invention can impart sufficient lubricity to the raw material in the cover soil by appropriate viscosity adjustment, while the conventional high-residual resin is used. Since the adhesiveness is inferior to the binder, the springback at the time of molding tends to be large and the filling property tends to be reduced. Therefore, only by using a binder having a low residual ratio such that the residual ratio of the binder is 30% by weight or less, the filling property of the obtained carbon-containing refractory becomes low, and it is difficult to obtain a dense structure. There is a problem that the corrosion resistance is reduced as in the case of the technology.

[0019]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a carbon-containing refractory which is excellent in spalling resistance and corrosion resistance. It is to provide a manufacturing method thereof.

[0020]

SUMMARY OF THE INVENTION As described above, the present inventors have found that the conventional technique of increasing the strength of a refractory by carbon bond reinforcement does not necessarily lead to an improvement in spalling resistance. Focusing on blind spots anew, and research on prevention methods for corrosion resistance deterioration, which is a problem when using a binder with a low residual ratio, or reduction in damage resistance when exposed to high temperatures for a long time. Was done. In addition, the refractory raw material usually used for carbon-containing refractories has a particle size ranging from extremely fine particles of about 0.01 mm to coarse particles of about 10 mm, and carbon-containing materials for suppressing joint damage and improving spalling resistance. Focusing on the fact that aggregates of a specific grain size are used according to the characteristics required for refractories (JP-B 5-155655, JP-B 7-17758, etc.), binders and fire-resistant materials are used. A survey was also conducted on the relationship with the particle size of raw materials. Based on the above research, the present inventors have obtained a high-fill, high-density refractory structure by using a binder having a low residual ratio and a refractory raw material having a constant particle size, and They have found that the carbon bond strength can be kept low, and have developed a carbon-containing refractory which is excellent in damage resistance and corrosion resistance.

The particle size of the refractory raw material referred to herein is
Generally determined or measured by a standard sieve used for classification of refractory raw materials, in the case of manufactured carbon-containing refractories, for example, the refractory raw material particles observed on the cut surface A biaxial average diameter or the like can be used.

That is, the carbon-containing refractory according to the present invention comprises:
"Refractory raw material, carbon raw material, raw material distribution containing binder
In a carbon-containing refractory made of a compound, the refractory raw material is 0.3% by weight when the entire refractory raw material is 100% by weight.
mm and less than 30% by weight and 1mm and more
A carbon-containing refractory containing 20 to 90% by weight, wherein the binder has a residual ratio of the binder of 30% by weight or less. (Claim 1) as a gist (items specifying the invention). In particular, the viscosity of the binder is 100 poise or less (Claim 2), so that the surface of the constituent material is sufficiently uniformly coated in the kneading operation. The lubricating properties of the raw materials are sufficiently ensured during the molding, and a dense molded body can be obtained. ・ The refractory raw material has at least a part of alumina and silicon carbide. Containing at least one refractory raw material selected from the group consisting of magnesium, magnesia and spinel (claim 3),
The carbon raw material contains graphite at least in part (claim 4), whereby the carbon raw material has an effect of being excellent in oxidation resistance and corrosion resistance. is there.

Further, the carbon-containing refractory according to the present invention comprises:
Claims containing refractory raw materials, carbon raw materials, and binders
A carbon-containing refractory comprising the raw material blend according to 1, wherein after firing, a ratio E / E between a flexural strength S (Pa) and an elastic modulus E (Pa) is obtained.
A carbon-containing refractory, wherein S ² is 2.7 × 10 ⁻⁴ (Pa) ⁻¹ or more. A "(claim 5).

Further, the method for producing a carbon-containing refractory according to the present invention comprises the steps of: "mixing, shaping, drying, and, if necessary, firing a raw material mixture containing a refractory raw material, a carbon raw material, and a binder. In a method of manufacturing a refractory,
When the total weight of the refractory raw material is 100% by weight, particles of 0.3 mm or less are reduced to 30% by weight or less and 1 m
m or more containing 20 to 90% by weight of the binder,
A method for producing a carbon-containing refractory, comprising using a raw material blend that is a binder having a binder residual ratio of 30% by weight or less. (Claim 6) as the gist (items specifying the invention).

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is an invention of a carbon-containing refractory excellent in spalling resistance and corrosion resistance by using a specific binder and a specific refractory raw material, and a method for producing the same. .

That is, the present invention is characterized by the fact that a binder having a low residual ratio, which has never been considered as a binder for use in a refractory material containing carbon for high durability, is positively used for improving the properties. The present invention goes beyond the conventional common sense and provides a completely new idea to the technical field of the carbon-containing refractory. At the same time, in the present invention, the use amount of the refractory raw material in the fine powder region of 0.3 mm or less and the coarse particle region of 1 mm or more is limited to obtain the desired carbon-containing refractory. .

In the present invention, the term "residual ratio of binder" refers to the weight ratio of the residue measured when a simple measured binder alone is heated to 800 ° C. in an oxygen-free atmosphere, or the actual carbon content. It means the weight ratio of the residue when heated to a temperature higher than the red heat temperature in the state of being present in the refractory structure. Further, in the present invention, the “carbon-containing refractory” includes any one of a fixed shape, an amorphous shape, and a fired or unfired.

Hereinafter, the present invention will be described in detail. First, the basic function of the “binder having a residual ratio of 30% by weight or less” (liquid or suspended), which is a feature of the present invention, will be described. First, the most important function of the binder is to ensure the formability by giving the clay an appropriate liquid component. In general, molding is performed by applying pressure to fill the constituent raw materials with high density, but a liquid component is required to reduce frictional resistance between the raw materials, and mixing or kneading is an operation for dispersing the liquid component on the particle surface of the constituent raw material. Done. Therefore, the binder used in the present invention needs to be easily wettable with a refractory raw material or a carbon raw material and to sufficiently uniformly coat the surface of the constituent raw material in the mixing or kneading operation, similarly to the binder generally used. Therefore, the viscosity is necessarily desirably low to some extent, preferably 100 poise or less, more preferably 60 poise or less at the mixing or kneading temperature.

Second, while obtaining high filling, the strength S
And that the elastic modulus E is kept low. The basic idea of the conventional binder technology for carbon-containing refractories was to use a binder having a high residual ratio as much as possible.However, in the present invention, the use of a binder having a low residual ratio has been changed by changing the idea. Features.

Since the binder used in the present invention has a lower residual ratio than conventional organic binders for carbon-containing refractories, the strength S and elastic modulus E of the refractory are kept low at high temperatures. That is, the binder used in the present invention has a lower residual ratio than the conventionally used binder, and has a low carbon content derived from the binder remaining in the refractory structure in a temperature range higher than the carbonization temperature. The number of bonding points to be performed is reduced.

Since the number of bonding points between the raw materials is reduced, the strength at high temperatures and the elastic modulus can be set to low values. In order to obtain this effect sufficiently, the residual ratio of the binder is preferably 30% by weight or less, more preferably 20% by weight.
The following are further preferred. 30% by weight binder remaining
If it exceeds, the strength and elastic modulus at high temperatures are increased, and the damage resistance coefficient is undesirably reduced.

The lower limit of the residual ratio of the binder is not particularly limited, but if it is extremely low, for example, if the residual ratio is less than 5% by weight, the strength at high temperatures becomes too low, and it becomes difficult to maintain the refractory structure. There are cases. In such a case, it is desirable to adjust the residual ratio within a range of 30% by weight or less so that the binder has a certain residual ratio.

As the binder having a low residual ratio used in the present invention, a binder mainly containing an organic substance is used in a liquid state or a suspension state. Examples of the organic substance used as a binder include: a. Resins such as phenolic resin, furan resin, epoxy resin, b. Aromatic organic polymer compounds such as pitch and tar; c. Glycerides such as stearic acid and palmitic acid; fatty acid derivatives such as waxes, fats and fatty oils; d. Hexavalent polyols such as sorbitol and mannitol,
Sugars such as maltose, trehalose and amylose and hydrolysates thereof, or pastes; e. Industrial waste liquids such as pulp waste liquid and molasses can be mentioned. The low-residual binder used in the present invention is not limited to the above-mentioned binders as long as the residual ratio of the binder is 30% by weight or less, and other synthetic and natural organic compounds may be used. Can be used for

A solvent or the like can be added to the binder having a low residual ratio used in the present invention in order to adjust the viscosity and tackiness. Examples of the solvent include alcohols such as ethanol and methanol, polyhydric alcohols such as ethylene glycol and glycerin, esters such as benzyl acetate and diethyl phthalate, as well as water, xylene, toluene and phenol, which are generally known as solvents. Can be used for The solvent that can be used is not particularly limited as long as it is sufficient to exhibit the effects of the present invention.

The mixing ratio between the solid content of the binder having a low residual ratio and the solvent used in the present invention can be mixed at an arbitrary ratio in order to adjust the desired viscosity and tackiness. However, in the case where the effects of the present invention are sufficiently exhibited, it is also possible to use a form in which solids and solvents are not classified.

The binder having a low residual ratio used in the present invention further includes a binder having a function sufficient for exhibiting the function and effect of the present invention, in addition to the above-mentioned organic substances as solid components. The use thereof is not particularly limited, and arbitrary ones such as a compound containing a metal element and a derivative thereof can be used.

The amount of the binder used in the present invention is not particularly limited since it varies depending on the type of the refractory raw material, the type and amount of the carbon raw material, and the intended use of the carbon-containing refractory of the present invention. In general, from the viewpoint of coating properties on the surface and the denseness of the hot structure, the amount of
1.5-15% by weight is suitable.

The refractory raw material that can be used in the present invention is not particularly limited, but commonly used refractory materials include oxides such as magnesia, calcia, dolomite, spinel, alumina, silica, chromia, zirconia, titania, and composite oxides thereof. Or coexisting raw materials or molten raw materials thereof, and non-oxides such as silicon carbide, silicon nitride, silicon oxynitride, silicon nitride, silicon carbide, and zirconium shelf.

In the present invention, regarding the particle size of the refractory raw material,
The amount of use is specified for a fine powder area of 0.3 mm or less and a coarse grain area of 1 mm or more. First, the use amount of the fine powder region of 0.3 mm or less and its operation and effect will be described. The refractory raw material in the fine powder region of 0.3 mm or less is uniformly dispersed by kneading and molding to form a matrix together with the carbon raw material. As the amount of the fine powder increases, the frequency of contact between the refractory raw materials in the matrix increases. When the residual ratio of the binder is high, the carbon particles derived from the binder cover the surface of the particles of the refractory raw material. The conclusion does not progress.

However, when the residual ratio of the binder is low, the amount of carbon coating the particle surface of the refractory raw material is reduced. When the amount of fine powder is large, the bonding points are increased by sintering, and the carbon-containing refractory is reduced. Disadvantageously, the strength and modulus of elasticity increase. Therefore, in the present invention, the refractory raw material
The content of particles of 0.3 mm or less is set to 30% by weight or less.

By specifying the use amount of the fine powder region to a certain amount or less, even when a binder having a low residual ratio is used,
It is possible to suppress an increase in bonding between refractory raw materials due to long-time heating at high temperature, that is, an increase in refractory strength and elastic modulus. When the refractory raw material contains more than 30% by weight of a fine powder area of 0.3 mm or less, the refractory strength and elastic modulus increase when heated for a long time at a high temperature, and the damage resistance decreases. It is not preferable. In order to further enhance the above-mentioned effects, the content of the particles of 0.3 mm or less of the refractory raw material is more preferably 25% by weight or less.

Next, the specification of the amount of use in the coarse grain region of 1 mm or more and its operation and effect will be described. The refractory raw material in the coarse-grained region of 1 mm or more firstly promotes the dispersion of the binder having a low residual ratio by the stirring effect in the mixing and kneading operations, and acts to form a uniform binder film on the surface of the raw material particles. At the time of molding, the coarse refractory raw material particles assist the pressure propagation inside the clay, and a high packing density can be obtained up to the center of the refractory. At this time, springback due to insufficient adhesive strength of the binder can be prevented by entanglement (blocking) between the refractory raw material particles, and a dense molded body can be obtained.

If the content of the particles of 1 mm or more of the refractory raw material used in the present invention exceeds 90% by weight, compactability is reduced due to interference between coarse particles, and a dense refractory cannot be obtained. It is not preferable. 1 mm of the refractory raw material
If the content of the above particles is less than 20% by weight, the effect of densification of the refractory due to improvement in moldability cannot be obtained, which is not preferable. The dense refractory structure thus obtained is retained from the subsequent drying or firing operation to the time of actual use, and can exhibit excellent corrosion resistance against erosion by molten metal or molten slag. In order to further enhance this effect, the content of the particles of 1 mm or more of the refractory raw material is more preferably in the range of 35 to 85% by weight.

As described above, the particle size of the refractory raw material used in the present invention is different from that of the prior art relating to the particle size of the raw material. For products, the reduction of thermal shock resistance is suppressed by limiting the fine powder area of 0.3 mm or less to a certain amount or less, and a dense refractory structure is obtained by using a certain amount of coarse grain area of 1 mm or more. A carbon-containing refractory having excellent corrosion resistance can be obtained by forming it, and a special synergistic effect can be obtained by combining with a technique using a binder having a specific residual ratio.

The carbon material that can be used in the present invention is not particularly limited, but those having a high fixed carbon content are preferable for maintaining a high-temperature structure, that is, ensuring corrosion resistance. Examples include natural graphite such as dendritic graphite, artificial graphite, electrode scrap, carbon fiber, and pyrolytic carbon.

The proportion of the carbon raw material varies depending on the type of the refractory raw material and the intended use of the carbon-containing refractory of the present invention, but is preferably in the range of 2 to 40% by weight of the carbon raw material. If the carbon material is less than 2%, the property of being difficult to wet with the slag of the carbon material cannot be sufficiently exhibited, and if it exceeds 40% by weight, the springback at the time of molding becomes large and a dense material cannot be obtained. Absent.

The carbon raw material used is preferably of high purity and crystallinity from the viewpoint of corrosion resistance and oxidation resistance, and it is often preferable to use a graphite raw material such as flake graphite. In addition, when more emphasis is placed on moldability, it may be preferable to use a carbon material having less deformability other than flake graphite.

The present invention can also be applied to carbon-containing refractories to which known additives such as silicon, aluminum, pitch powder, and mesophase pitch are added, if necessary, which are also included in the present invention. It is.

Next, a method for producing the carbon-containing refractory of the present invention will be described. In the present invention, first, a binder and, if necessary, additives are added and kneaded to a raw material mixture composed of a refractory raw material and a carbon raw material to obtain a clay pad. After molding the clay,
By baking at 120 to 500 ° C., an unfired carbon-containing refractory can be produced. In some cases, operations for adjusting the secondary raw materials such as granulation, coating, temporary forming, and crushing can be performed between these operations. Further, the carbon-containing refractory obtained as described above can be fired in a reducing atmosphere or a non-oxidizing atmosphere at about 600 to 1500 ° C. to produce a fired product.

The carbon-containing refractory obtained as described above is a raw material containing a refractory raw material, a carbon raw material, and a binder.
A carbon-containing refractory comprising a blend , wherein after firing, the ratio E / S ^{2 of} the flexural strength S (Pa) to the elastic modulus E (Pa) is 2.7 × 10 ^-4 (Pa)
It is a carbon-containing refractory of ^-1 or more. When the ratio E / S ^{2 of the} flexural strength S (Pa) to the elastic modulus E (Pa) is 2.7 × 10 ⁻⁴ (Pa) ⁻¹ or less, the thermal shock damage resistance is low, so that cracks easily propagate, and It is not preferable because the polling property is lowered.

The term “firing” used herein does not particularly limit the temperature, but generally heating at 600 ° C. or higher is often referred to as firing, and the upper limit of the firing temperature for refractories. Is about 1800 ° C., and in the present invention, the temperature range is defined as the firing temperature. For the elastic modulus,
Although the static elastic modulus and the dynamic elastic modulus are known, usually, when a refractory is measured, the two values often do not match. The "elastic modulus" referred to in the present invention means a dynamic elastic modulus measured by a sound wave method or a striking method.

[0052]

EXAMPLES Next, examples of the present invention will be described together with comparative examples to explain the carbon-containing refractory of the present invention and the method for producing the same in more detail. However, the present invention is limited to the examples described below. Not something. Table 1 shows the binders used in the following Examples and Comparative Examples.

[0053]

[Table 1]

Examples 1 to 8 and Comparative Examples 1 to 6 (Examples and Comparative Examples of Alumina / Carbon) Various raw materials including the binders shown in Table 1 were mixed at a ratio shown in Table 2 and kneaded. 230 × 114 × 65mm at 150MPa pressure
Was molded under pressure. The molded body was baked at 200 ° C. to prepare an unfired carbon-containing refractory. This unfired carbon-containing refractory was reduced and fired at 1500 ° C. for a long time of 20 hours.

The measurement of S / E as an index of the thermal shock fracture resistance coefficient, E / S ^{2 as} the index of the thermal shock damage resistance coefficient, and the corrosion resistance index of Examples 1 to 8 and Comparative Examples 1 to 6 are as follows. The results are shown in Table 2 together with the bulk specific gravity of the unfired carbon-containing refractory, the flexural strength after firing, the elastic modulus (dynamic elastic modulus according to the impact method), and the spalling resistance index. .

○ S / E, which is an index of thermal shock fracture resistance coefficient,
E / S ² is an index of thermal shock damage resistance coefficient. Flexural strength and elastic modulus of the above unfired carbon-containing refractories after reduction firing at 1500 ° C for 20 hours for a long time (dynamic elastic modulus by impact method) ) Was measured, and from the measured bending strength S and elastic modulus E, S / E as an index of thermal shock fracture resistance coefficient and E / S ^{2 as} an index of thermal shock damage resistance coefficient were calculated. .

O Corrosion resistance index: Corrosion resistance index is obtained when a steel melted in a crucible formed of the above-mentioned fired carbon-containing refractory in a high-frequency induction furnace and steelmaking slag are added thereto and eroded at a temperature of 1650 ° C. It was calculated from the amount of erosion. (The higher the value, the better the corrosion resistance.)

[0058]

[Table 2]

Examples 9 to 15 and Comparative Examples 7 to 11 (Examples and Comparative Examples of Magnesia Carbon)
The various raw materials including the binder shown in Table 3 were mixed at the ratio shown in Table 3 and kneaded, and then 230 × 114 × 65 m at a pressure of 150 MPa.
m. The molded body was baked at 200 ° C. to prepare an unfired carbon-containing refractory. This unfired carbon-containing refractory was reduced and fired at 1500 ° C. for a long time of 20 hours.

In Examples 9 to 15 and Comparative Examples 7 to 11, the S / E as an index of the thermal shock fracture resistance coefficient, the E / S ^{2 as} the index of the thermal shock damage resistance coefficient, and the corrosion resistance index were measured as described above. The results are shown in Table 3 together with the bulk specific gravity of the unfired carbon-containing refractory, the flexural strength after firing, the elastic modulus (dynamic elastic modulus by the impact method), and the spalling resistance index.

[0061]

[Table 3]

As is clear from Tables 2 and 3, the carbon-containing refractory of the present invention has a bulk specific gravity equal to or higher than that of the baking, exhibits high corrosion resistance, and has a high corrosion resistance at a high temperature. It is clear that the strength is kept low even after the reduction firing for a long time, and the thermal shock damage resistance is excellent. That is, the carbon-containing refractory of the present invention has significantly improved resistance to thermal shock damage as compared to conventional products, and is also excellent in corrosion resistance. It is clear that when used as a lining material, high durability can be obtained.

[0063]

According to the present invention, as described in detail above, as a refractory raw material, when the entire refractory raw material is 100% by weight, particles of 0.3 mm or less are reduced to 30% by weight or less and particles of 1 mm or more. A carbon-containing refractory having excellent spalling resistance and corrosion resistance by using a binder containing 20 to 90% by weight and having a binder residual ratio of 30% by weight or less as a binder. And an excellent effect of being able to provide a method for producing the same.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 9-241067 (JP, A) JP 6-345525 (JP, A) JP 7-33513 (JP, A) JP 3 197346 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 35/00-35/22 C04B 35/622-35/636

Claims (6)

(57) [Claims] 1. A carbon-containing refractory comprising a raw material mixture containing a refractory raw material, a carbon raw material, and a binder, wherein the refractory raw material is 0.3 mm or less when the entire refractory raw material is 100% by weight. The carbon-containing refractory contains 30% by weight or less of particles of the above and 20 to 90% by weight of particles of 1 mm or more, and the binder has a residual ratio of 30% by weight or less. 2. The carbon-containing refractory according to claim 1, wherein the viscosity of the binder is 100 poise or less. 3. The refractory raw material at least partially contains at least one refractory raw material selected from the group consisting of alumina, silicon carbide, magnesia, and spinel. 2. The carbon-containing refractory according to 1. 4. The carbon-containing refractory according to claim 1, wherein the carbon raw material contains graphite at least in part. 5. A carbon-containing refractory comprising the raw material blend according to claim 1, comprising a refractory raw material, a carbon raw material, and a binder, wherein after firing, the bending strength S (Pa) and the elastic modulus E (Pa ) are obtained. )
A carbon-containing refractory having a ratio E / S ² of at least 2.7 × 10 ⁻⁴ (Pa) ⁻¹ . 6. A method for producing a carbon-containing refractory material by mixing, molding, drying and, if necessary, firing a raw material mixture containing a refractory raw material, a carbon raw material, and a binder, wherein the refractory raw material comprises: Assuming that the entire refractory raw material is 100% by weight, particles having a size of 0.3 mm or less are 30% by weight or less and
m or more containing 20 to 90% by weight of the binder,
A method for producing a carbon-containing refractory, comprising using a raw material mixture having a binder residual ratio of 30% by weight or less.