JP3638081B2 - Refractory material containing low carbonaceous carbon and method for producing the same - Google Patents

Description

【００８０】
（実施例，参考例、比較例の試料 No. １〜１８）
次の表２に示す"原料の配合比率(重量％)"にしたがって各種原料を混合し混練した後、150MPaの圧力で230×114×65ｍｍの寸法に加圧成形した。次に、この成形体を200℃でベーキングしてれんが試料No. １〜１８を作成した。
【００８１】
得られた試料の“気孔率(べ−キング後の見掛け気孔率)”を表２に示す。また、得られた試料に対し、1500℃で20時間という長時間にわたる還元焼成を施した後の“弾性率(打撃法による動弾性率)”を測定し、その結果を表２に示した。
さらに、1400℃で10時間加熱して完全に酸化させた後の“圧縮強さ(MPa)”および“耐スポーリング性指数”を同じく表２に示す。
【００８２】
表２に示す“耐スポーリング性指数”は、試料を1600℃の溶銑に浸漬した時に発生する亀裂の本数(熱衝撃テスト後の発生亀裂数)と損傷度合いを一定の規則にしたがって数値化する方法で評価(→耐火物，44[2](1992)，P75〜82参照)した後に指数化したものであり、この数値が大きいほど“耐スポーリング性に優れている”ことを意味している。
【００８３】
表２に示す試料 No. ４，８，９，１２は本発明の実施例であり、試料 No. １〜３，５〜７，１０，１１は参考例である。また、試料 No. １３〜１８は比較例である。
なお、表２を参照して、比較例である試料 No. １３〜１８について説明すると、試料 No. １３，１４は、試料 No. １，２（参考例）に対する比較例であり、試料 No. １５，１６は、試料 No. ３（参考例 ) ，４（実施例）に対する比較例である。
【００８４】
さらに、試料 No. １７は、試料 No. ６（参考例）に対する比較例であり、また、試料 No. １８は、本発明の低カーボン質炭素含有耐火物(固定炭素分：0.2〜5重量％)に対する比較例である。
【００８５】
【表２】

【００８６】
表２から明らかなように、比較例である試料 No. １３〜１８に対して本発明の低カーボン質炭素含有耐火物（試料 No. ４，８，９，１２）は、ベーキング後の気孔率が低く緻密なものが得られており、かつ高温下で長時間還元焼成した後においても強度が低く保持されて耐スポーリング性に優れており、しかも1400℃で完全に酸化させた後の強度が高く、酸化後にも高耐用の耐火物として耐用することのできる優れた特性を有していることが理解できる。
【００８７】
即ち、本発明の低カーボン質炭素含有耐火物（試料 No. ４，８，９，１２）は、従来のものに比べて長時間加熱された場合の耐スポーリング性が大幅に向上しており、かつ緻密質であって酸化後の強度も高いことから、カーボン量の少ないことが求められる用途、例えば製鉄用容器の内張り材等として使用した場合、溶鋼へのカーボンピックアップが少なく、かつ高耐用が得られることは明らかである。
また、表２から明らかなように、本発明の低カーボン質炭素含有耐火物（試料 No. ４，８，９，１２）は、参考例（試料 No. １〜３，５〜７，１０，１１）に比し、特に耐スポーリング性が向上していることがわかる。
【００８８】
【発明の効果】
本発明は、以上詳記したとおり、耐火性原料と炭素を含有する炭素質原料とを含む原料配合物において、原料配合物の熱間残留分100重量％に対して炭素質原料の固定炭素分が0.2〜5重量％であって、しかも前記（ａ）〜（ｄ）を特徴とし、これにより、緻密な組織を有していながら高温下で長時間使用した場合にも過度の焼結が進行せず、良好な耐スポーリング性を維持できる"高耐スポーリング性，高耐食性で、かつ溶鋼へのカーボンピックアップを極力防止することのできる低カーボン質の炭素含有耐火物"を提供することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a carbon-containing refractory having a low carbon content and a method for producing the same, and more particularly to a low-carbon carbon-containing refractory excellent in spalling resistance and oxidation damage resistance and a method for producing the same.
[0002]
[Prior art]
[Description of the background for the requirement of low-carbon carbon-containing refractories]
Refractories containing carbon raw materials such as graphite are widely used as various metallurgical refractories because they exhibit high durability due to the properties of carbon such as high thermal conductivity and resistance to wetness with molten slag. In recent years, the use of high-resistance carbon-containing refractories has been spreading with the upgrading of steel products.
However, the conventional carbon-containing refractory contains a relatively large amount of carbon in order to sufficiently exhibit the above-described characteristics of carbon.
[0003]
On the other hand, as the use range of carbon-containing refractories expands, the dissolution of carbon contained in refractories into molten steel (carbon pickup) has become a problem, and refractories with a lower carbon content are required. ing.
In addition, against the backdrop of further improvement in steel quality, demands for lowering the carbon of steel have become more and more strict, and refractories containing a large amount of carbon contaminate molten steel with carbon pickup, so refractories with less carbon content. In particular, a total carbon amount of “5% or less” is desired.
[0004]
Furthermore, since the use conditions of the refractory used for the treatment of ultra-low carbon steel become more severe, damage to the refractory increases due to this severe use condition, and carbon from the refractory to the molten steel is increased. The amount of dissolution also increases. Therefore, also from this point, a refractory with a smaller amount of carbon is required.
[0005]
[Explanation of “Examination Examples in Prior Art” for low-carbon carbon-containing refractories Part 1]
Conventional carbon-containing refractories have a problem that the spalling resistance decreases when the amount of carbon is reduced [Reference: Refractories, 44 [2] (1992), P75-82].
In order to solve this problem, studies have been conducted for the purpose of improving the spalling resistance in a low carbon composition.
[0006]
For example, in the stage of forming a refractory, there are cases where the filling property is lowered to increase the porosity, and the elastic modulus is reduced to increase the spalling resistance.
However, in this case, since the denseness of the refractory structure is lost and the corrosion resistance, wear resistance, oxidation resistance and the like are remarkably lowered, it is not widely performed.
[0007]
Further, for example, “Refractories, 44 [11] (1992), P640” and Japanese Patent Laid-Open No. 5-24911 disclose low carbonaceous MgO— with improved spalling resistance by using expanded graphite. C-based refractories have been proposed.
However, if expanded graphite is used extensively, the filling property of the structure is lowered, so that oxidation resistance, wear resistance, corrosion resistance, and the like are lowered, which is not preferable. In addition, it is known that the effect of improving the spalling resistance of expanded graphite is hardly obtained in the region where the amount of graphite is 5% by weight or less [J. Ceram. Soc. Japan, 102 [1] (1994). ), See pages 23 to 28], which is not a technique that can improve the spalling resistance of low-carbon materials.
[0008]
On the other hand, “Shinagawa Technical Report, Vol.38 (1995), P23-32” is a technology for reducing carbon while maintaining spalling resistance, and reducing the amount of metal added and coarsening magnesia. "MgO-C brick for converter steel outlet sleeve" having a carbon content of 8% by weight or 6% by weight has been proposed. This material shows high durability when used in a converter steel outlet sleeve, and is shown to be effective.
However, the low carbonaceous MgO-C brick for the steel outlet sleeve of the converter contains 6% by weight of carbon even if it is the smallest, and from the viewpoint of preventing carbon pickup to the molten steel, it should be as low as possible. The desired carbon-containing refractory cannot be an optimal material.
[0009]
Similarly, as a technology for reducing carbon while maintaining spalling resistance, “Materials and Processes, CAMP-ISIJ, VoL.4 (1991), P1225” includes coarse magnesia and a high softening point pitch. "Low-graphite MgO-C bricks for ladle slag lines" having a carbon content of 7% by weight, which is added and refined into graphite, has also been proposed. This low-graphite MgO-C brick for ladle slag lines shows high durability when used in a ladle slag line part and is shown to be effective.
However, the low-graphite MgO-C brick for ladle slag lines contains 7% by weight of graphite even if it is said to be low-graphite, and has as little carbon as possible from the viewpoint of preventing carbon pickup into molten steel. The carbon-containing refractory that is desired to be used is not an optimum material like the above-mentioned “MgO—C brick for converter outlet sleeve”.
[0010]
On the other hand, among the techniques already disclosed, as described in, for example, JP-A-56-26766, JP-A-7-17758, etc., the composition range (blending amount) of carbon or graphite raw material Many are known to have 5% by weight or more.
However, since these contain at least 5% by weight of carbon, they cannot be said to be a technology that can provide a carbon-containing refractory that is desired to have as little carbon as possible from the viewpoint of preventing carbon pickup in molten steel.
[0011]
Further, among the techniques already disclosed, as described in, for example, JP-A-4-288469, JP-A-5-330904, JP-A-6-235557, etc., carbon or graphite raw material In which the composition range (blending amount) is 3% by weight or more, or as described in, for example, JP-A Nos. 7-118057 and 7-126060, etc. Are known.
However, none of these examples show an example in which the carbon raw material is less than 5% by weight, and no specific examples relating to a region having a particularly small amount of carbon, so that it is possible to provide an optimal low carbon material. Is not disclosed.
[0012]
[Explanation 2 of "Examination in prior art" for low-carbon carbon-containing refractories Part 2]
As described above, in order to prevent carbon pickup from molten steel, the amount of carbon in the refractory must be 5% by weight or less, more preferably low carbon.
[0013]
What is meant by “carbon amount” in this case is the “amount of fixed carbon” contained in the refractory when it is used in the hot state. Carbon will also be included.
Therefore, when an organic binder is used, for example, in a “refractory having a carbon amount of 5% by weight”, as a matter of course, the solid carbon raw material is less than 5 wt. It will constitute part of the carbon in the refractory.
[0014]
In the present invention described in detail later, in order to clarify this point, the solid carbon raw material and the organic binder (or pitch, carbon black) are combined into a “carbonaceous raw material”, and the total fixed carbon content thereof, It defines the carbon content of refractories. In view of this, when a “refractory having a carbon amount of 5% by weight or less” is required, the blending ratio of the solid carbon raw material is necessarily less than 5% by weight.
[0015]
As described above, most of the prior art relates to a material having a relatively large amount of carbon. On the other hand, studies on refractories having a carbon amount of 5% by weight or less are also being conducted. For example, in JP-A-9-309762, in a refractory containing 1 to 5% by weight of a carbon raw material, the metal and boride contents are limited to a certain level or a specific pitch is added. A “carbon-containing refractory for a vacuum degassing furnace” is disclosed which has improved spalling resistance while using low-granular MgO.
[0016]
Although this low-carbon, carbon-containing refractory has better spalling resistance than conventional low-carbon materials, it can be fired by contact between refractory raw material aggregates due to long-term heat in actual use. In some cases, the kneading progresses excessively to increase the elastic modulus, and conversely, the spalling resistance may decrease, and it is not possible to provide a low carbon material having stable spalling resistance over a long period of time.
[0017]
Further, for example, Japanese Patent Publication No. 7-108805 and Japanese Patent Application Laid-Open No. 5-4861 disclose magnesia carbon bricks having improved spalling resistance by adding mesophase-containing pitch powder.
[0018]
However, these were studied and developed for materials with a relatively large amount of carbon based on the contents, and an optimal method for improving the spalling resistance particularly in a region with a small amount of carbon was disclosed. It ’s hard to say.
Also, in these examples, examples where the blending amount of graphite is “0% by weight, 1% by weight, 3% by weight, 4% by weight”, etc. are shown, but all contain a large amount of metal additives. Therefore, a high elastic modulus cannot be avoided in a high temperature range, and the spalling resistance is low. Therefore, even from this point of view, it is difficult to say that a technique capable of providing a low-carbon material that is excellent in spalling resistance and melt resistance is shown.
[0019]
For example, JP-A-4-367556 discloses a method for improving the spalling resistance by using pitch and / or tar and a pitch-soluble phenol resin.
[0020]
However, this was also studied and developed for materials with a relatively large amount of carbon based on the content, and an optimal method for improving the spalling resistance particularly in a region with a small amount of carbon was disclosed. It ’s hard to say.
Also, in this example, there are examples in which the blending amount of graphite is “0 wt%, 3 wt%, 5 wt%”, etc., but since the added amount of pitch or tar is large, The porosity increases and the compactness decreases, or since a certain amount of metal is contained, a high elastic modulus cannot be avoided at high temperatures, and the spalling resistance is low. Therefore, in this case as well, it is difficult to say that a technique capable of providing a low carbon material that is excellent in spalling resistance and melt resistance is shown.
[0021]
Further, for example, in the above-mentioned JP-A-7-1206060, a method for providing a carbon-containing refractory having excellent spalling resistance, wear resistance, and corrosion resistance by adding pitch powder having a relatively low softening temperature. Is disclosed.
[0022]
However, this was also studied and developed for a material with a relatively large amount of carbon based on the content, and an optimal method for improving the spalling resistance particularly in a region with a small amount of carbon was disclosed. It is hard to say that it has been done.
Also, in this example, an example in which the blending amount of graphite is “5% by weight” is shown. However, since the amount of pitch added is large, the porosity after baking and hot increases. Denseness tends to decrease. Therefore, it is difficult to say that this also shows a technique that can provide a low carbon material that is excellent in both spalling resistance and melting resistance.
[0023]
Furthermore, for example, JP-A-8-295555 provides a low-carbon, carbon-containing refractory that is excellent in spalling resistance, slag infiltration resistance, and corrosion resistance by using elastic artificial graphite. A method is disclosed.
[0024]
However, even when this method is used, sintering due to contact between refractory raw material aggregates progresses excessively due to long-term heat in actual use, resulting in high elastic modulus and conversely reduced spalling resistance. There is a problem that it is difficult to obtain a low carbon material having stable spalling resistance over a long period of time.
Further, since artificial graphite having elasticity is used, it is difficult to obtain a dense molded body, and the porosity tends to be high. Furthermore, in the examples, a total carbon amount of “1 to 4% by weight” is shown, but since many of them contain a certain amount of metal additives, a high elastic modulus is obtained in a high temperature range. Therefore, it is difficult to obtain sufficient spalling resistance.
For these reasons, it is difficult to say that a technique capable of providing a low-carbon material that is excellent in both spalling resistance and melting resistance is also shown in this case.
[0025]
Also, for example, in JP-A-9-87007, by adding aluminum together with a resin binder to generate spinel in the refractory structure, it is excellent in slag infiltration resistance, “magnesia unfired without carbon material addition A method of providing a “brick” is disclosed.
However, when this method is used, the added aluminum forms carbides, and in the reaction process that changes into spinel, it is inevitable that the refractory has a high elastic modulus, and the spalling resistance is reduced. There is a problem of doing.
[0026]
This technology also attempts to suppress oversintering of aggregates by generating spinel on the surface of magnesia particles, but in the region where the amount of carbon is very small, the contact frequency between aggregates is very high. Therefore, it is not sufficient that this technology alone is sufficient to prevent the sintering, and there is a case where the elastic modulus is increased due to long-time heat application in actual equipment, and the spalling resistance may be lowered. In addition, if the amount of aluminum added is increased in order to obtain a sufficient amount of spinel, the increase in elastic modulus in the reaction process becomes remarkable, and there is a limit to further promote spalling.
Therefore, it is not sufficient to obtain a low carbon material having stable spalling resistance over a long period of time.
[0027]
Furthermore, since the dispersion of carbon in the refractory structure depends only on the resin binder, depending on the selection of the resin, the carbon dispersion is not uniform, and it promotes oversintering of the aggregates at high temperatures. Alternatively, if the resin binder is not sufficiently dispersed, a sufficiently dense molded body cannot be obtained, and there is a problem that the porosity is increased.
[0028]
[Problems to be solved by the invention]
As seen in the prior art described above, in a region where the amount of carbon is very small, it cannot be said that sufficient studies have been made to obtain high spalling resistance and fusing resistance, and a low-carbon refractory material. A low-carbon, carbon-containing refractory having excellent characteristics sufficient to meet the demand for the above has not yet been obtained.
[0029]
By the way, in the “low carbonaceous carbon-containing refractory that can prevent carbon pickup to molten steel as much as possible” intended by the present invention, since the amount of carbon is small, the contact frequency between aggregates made of refractory raw materials is very high. Has the essential organizational characteristic of becoming higher.
[0030]
When considering the spalling resistance of low carbon materials, it is an important issue that the heat spalling resistance decreases due to the decrease in thermal conductivity and the increase in thermal expansion coefficient due to the low amount of carbon. However, since there is much contact between aggregates, when it is used for a long time at high temperature, sintering proceeds excessively and the refractory has a high elastic modulus, which causes thermal or structural It has become recognized that the problem of spalling is an important problem, and that the latter is more necessary to develop low carbon materials.
[0031]
If the amount of carbon is reduced, it is unavoidable that the aggregates can easily come into contact with each other. However, to reduce the direct contact as much as possible, low carbon materials can be used stably at high temperatures for a long time. This is an important issue.
In order to reduce the contact frequency between aggregates, it is possible to reduce the filling density of the refractory slightly and suppress the oversintering progress at high temperature, but when considering the durability of the refractory The direction of sacrificing its denseness does not seem preferable.
[0032]
As a means for solving these problems, the present inventors intend to develop a “low carbonaceous carbon-containing refractory material having a high density as well as a spalling resistance” when used for a long time at a high temperature. As a result of extensive research, the present invention has been completed.
[0033]
In other words, the object of the present invention is that “high resistance to high spalling” can be maintained without excessive sintering even when used at a high temperature for a long time while having a dense structure. An object of the present invention is to provide a low-carbon, carbon-containing refractory material that has a spalling property and a high corrosion resistance and that can prevent carbon pick-up to molten steel as much as possible, and a method for producing the same.
[0034]
[Means for Solving the Problems]
  The low carbonaceous carbon-containing refractory according to the present invention includes a refractory raw material and a carbonaceous raw material containing carbon.
-The fixed carbon content of the carbonaceous raw material is 0.2-5 wt% with respect to 100 wt% of the hot residue of the raw material blend,
(A) At least a part of the carbonaceous raw material, SolidMore than 25% by weight of constant carbonBigViscosity is less than 200 poiseAn organic binder and a pitch having a β-resin content of 10% by weight or more;(Claim 1))
(B)Carbon black was further used for at least part of the carbonaceous raw material (claims)2)
(C)Use of magnesia, alumina, and spinel as at least part of the refractory raw material (claims)3), [For example, using magnesia, magnesia and alumina, spinel, magnesia and spinel]
(D)The content of the metal additive is 4% by weight or less (claim)4)
(E)The apparent porosity after baking is 4% or less (claims)5)
(F)The compressive strength after complete oxidation by heating at 1400 ° C. for 10 hours is 25 MPa or more.6)
Is a feature (matter specifying the invention), thereby achieving the object.
[0035]
  Moreover, the method for producing a low carbonaceous carbon-containing refractory according to the present invention comprises the above claims 1 to 3.6A method for producing a low-carbon, carbon-containing refractory according to any one of
-The amount of fixed carbon of the carbonaceous raw material does not exceed 0.2 to 5% by weight with respect to 100% by weight of the hot residue of the raw material refractory including the refractory raw material and the carbonaceous raw material containing carbon. Mixing carbonaceous raw materials (claims)7)
Is a feature (matter specifying the invention).
[0036]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, the present invention will be described in detail. First, the organic binder used in the present invention [→ see (a) above], pitch [→ said above(A)Reference], carbon black [→ above(B)Reference], refractory raw material [→ above(C)See], metal additives [→ above(D)Each function and effect of [Ref] will be described.
[0037]
[Explanation of effects of “organic binder” used in the present invention]
・ First function of organic binder
The “organic binder” that can be used in the present invention is, first of all, as a basic function of the binder, to ensure moldability by giving an appropriate liquid to the clay.
[0038]
Molding is generally performed by applying pressure to fill the constituent raw materials at a high density, but a liquid component is required to reduce the frictional resistance between the raw materials, and mixing or kneading is performed as an operation for dispersing the liquid component on the particle surface of the constituent raw material. Is done.
In the case of a low carbon material, since there are few carbon raw materials, such as graphite, which give slipperiness to a clay at the time of molding, and friction between raw material aggregates increases, the dispersibility of this binder becomes more important.
[0039]
Therefore, the “organic binder” used in the present invention needs to be easily wetted by the refractory raw material and the carbon raw material and coat the surface of the constituent raw material sufficiently uniformly in the mixing and kneading operations. In the mixing and kneading operations, if the organic binder can sufficiently cover the surface of the raw material, sufficient lubricity can be obtained even when the aggregates are in contact with each other during molding, and a dense molded body can be obtained.
Therefore, the viscosity of the organic binder used in the present invention is desirably lower than a certain level, preferably 200 poise or less, more preferably 100 poise or less.
[0040]
By using these highly dispersible organic binders, the low carbonaceous carbon-containing refractory material of the present invention has a high filling property by a molding operation, and is a non-fired refractory material having a low porosity. Can be obtained.
As a result, even when subjected to slag, hot metal, or molten steel attack, it can exhibit high durability, and since the refractory raw material is densely packed, it is subject to oxidative damage at high temperatures such as 1400 ° C. Even when the carbon in the refractory has completely disappeared, it can have a certain strength or more and can be used as a refractory having high corrosion resistance even after oxidation.
[0041]
・ Organic bindersecondAbout functions
  "Organic binder" that can be used in the present inventionsecondThe function is that, even when the refractory is exposed to a high temperature for a long time, excessive sintering of the refractory raw materials is suppressed to suppress an increase in elastic modulus.
[0042]
The organic binder uniformly dispersed in the refractory structure by mixing and kneading operations is carbonized to carbon when the refractory is exposed to a high temperature. At this time, when the organic binder has a certain amount of fixed carbon or more, a thin and uniform carbon film is formed on the particle surface of the refractory raw material aggregate.
And since the carbon film formed on the particle surface of the refractory raw material can exist stably even at a high temperature, the direct contact between the refractory raw materials is blocked for a long time as long as it does not disappear by oxidation. be able to. As a result, excessive sintering does not proceed even when the refractory is used at a high temperature for a long period of time, generating factors that promote spalling, such as an abnormal increase in elastic modulus and formation of a structural gap near the working surface. Can be prevented.
[0043]
The effect of the carbon film derived from the organic binder is much more effective than the effect of suppressing oversintering by, for example, reducing the particle size of the graphite raw material and dispersing it uniformly. It is an important component in “low-carbon, carbon-containing refractories”.
Therefore, in order to sufficiently obtain this effect, the fixed carbon of the binder is desirably higher than a certain level, preferably 25% by weight or more, more preferably 35% by weight or more.
[0044]
[Description of the effect of the “pitch” used in the present invention]
Since the above-mentioned organic binder needs to have a high fixed carbon, it is common to use organic polymers having a large molecular weight as the main component, or to polymerize using a polymerization reaction. Typical examples are tar and thermosetting resin.
[0045]
Pitch is also considered to be included in the organic binder in a broad sense, but in the present invention, its effect is not the same as that of the organic binder described above, and is therefore considered as a different component.
The most important effect of the pitch is the effect that the pitch dispersed in the structure melts and softens and expands into the surrounding structure in the process of being heated by the refractory, and penetrates into fine voids.
[0046]
If the entire surface of the refractory raw material aggregate is sufficiently covered with organic binder, the aggregate particle surface can be blocked with a carbon coating at high temperatures to prevent oversintering. Even when an organic binder having a high viscosity is used, sufficient dispersion and coating may not be achieved depending on the mixing and kneading conditions.
Even in such a case, by dispersing the pitch in the structure, the pitch is melted and softened in the process of heat treatment of the refractory, and diffused between the aggregate particle surface and the aggregate particle not sufficiently covered with the organic binder. , Penetrate to form a pitch film.
[0047]
The pitch that diffuses and penetrates between the surface of the aggregate particles and between the aggregate particles is carbonized when the refractory is exposed to a higher temperature, and the stable contact that blocks the direct contact between the aggregate particles over a long period of time even at high temperatures. A carbon film is formed.
Therefore, the purpose of use of the pitch used in the present invention is to form a carbon film between the particles of the refractory raw material and between the particles to suppress oversintering at a high temperature. The purpose of use is different from “enhancement of tissue strength by strengthening carbon bonds”, which was intended for use.
[0048]
On the other hand, even if it is generally called a pitch, there are various contents. Usually, pitch consists of an organic polymer containing a benzene ring, and its molecular weight ranges widely from a relatively low molecular weight to a very high molecular weight. In a raw material called “pitch”, these molecular weights Contains a variety of different organic polymers.
[0049]
The present inventors have examined various pitches, and among these pitches having a wide molecular weight distribution, a pitch containing a large amount of an intermediate molecular weight called “β-resin (QI-TI)” is particularly preferable. I found it suitable.
By containing a large amount of β-resin, the pitch has sufficient diffusibility at the time of melt softening, and the fixed carbon becomes high, so that a dense carbon film can be effectively formed in the refractory structure.
[0050]
β-resin decreases when the molecular weight of the entire pitch is small, and also decreases when the molecular weight of the entire pitch is very large.
When the overall molecular weight of the pitch is small and the amount of β-resin is small, the diffusibility is obtained, but the fixed carbon is low, and an effective carbon film is difficult to be formed. Further, when the molecular weight of the entire pitch is large and the β-resin content is small, although the fixed carbon is high, sufficient diffusivity cannot be obtained, and therefore an effective carbon film is difficult to be formed.
[0051]
Therefore, in order to sufficiently obtain the carbon film forming effect by the pitch, the content of β-resin in the pitch is desirably higher than a certain level, preferably 10% by weight, more preferably 20% by weight or more. Is preferred.
[0052]
[Description of the effects of “carbon black” used in the present invention]
In the present invention, carbon black can also be used as a means for suppressing oversintering between refractory material aggregates.
As described above, in order to effectively block the contact between aggregate particles with a small amount of carbon, it is most effective to use an organic substance having a high fixed carbon content and excellent dispersibility. Since the particle diameter is very fine, it can be uniformly dispersed in the refractory structure, and therefore, an effective oversintering suppression effect can be exhibited.
[0053]
Normally, carbon black has a very small particle size of around 0.1 μm, and therefore has a feature that the degree of dispersion in the refractory structure is significantly higher than other carbon materials such as graphite and coke. ing.
That is, by adding carbon black, the surface of the aggregate particles is coated with very fine carbon particles. Moreover, since carbon black has a high fixed carbon, the contact between aggregate particles is blocked for a long time even at a high temperature, and an effect of suppressing oversintering is obtained.
[0054]
[Explanation of the effect of "refractory raw materials (magnesia, alumina, spinel)" used in the present invention]
In the present invention, “magnesia, alumina, spinel” can be used as a means for suppressing oversintering between refractory raw material aggregates. For example, magnesia, magnesia and alumina, spinel, magnesia and spinel can be used.
[0055]
As mentioned above, in order to prevent oversintering of aggregates in a region with a small amount of carbon, it is effective to use a carbonaceous raw material having a high fixed carbon content and excellent dispersibility. It is also effective to suppress oversintering by using a specific material as the raw material aggregate.
[0056]
In general, since refractories used for iron making or steel making are used at high temperatures under the presence of slag, alumina or magnesia having high corrosion resistance is used as the main constituent material.
The same applies to refractories containing carbon, and “magnesia-carbon bricks” mainly composed of magnesia and “alumina-carbon bricks” mainly composed of alumina are widely used.
[0057]
However, in the “low carbonaceous refractory material containing carbon” intended by the present invention, as described above, oversintering between refractory raw material aggregates becomes a problem, and prevention thereof is a problem.
Here, when the refractory raw material aggregate is composed of “magnesia only” or “alumina only”, sintering due to contact between the aggregates is relatively easy to proceed, resulting in a long time at a high temperature. When used, it tends to cause oversintering.
[0058]
In the present invention, in order to suppress this, spinel (magnesia-alumina spinel) can be used as the refractory raw material aggregate, or a combination of magnesia and alumina can be used.
Spinel has a lower sinterability at high temperatures than magnesia or alumina, and it can be used at least as part of a refractory aggregate to prevent over-sintering of low-carbon materials and high elastic modulus. It is particularly effective. In addition, the use of a combination of magnesia and alumina in at least a part of the refractory aggregate also produces an effect of suppressing spin sintering by generating spinel in the refractory structure at a high temperature.
[0059]
[Explanation on “Restriction of Content of Metal Additives” in the Present Invention]
In the present invention, the amount of metal added is limited to a certain level or less in order to prevent a high elastic modulus when heated at high temperatures.
[0060]
It is known that when a metal additive is added to a carbon-containing refractory, it reacts with carbon and the like at high temperatures to increase strength and elastic modulus.
This tendency, especially the increase in elastic modulus, has a great influence on the hot spalling resistance of low carbon materials. If the amount of metal added is too large, the increase in elastic modulus becomes remarkable and the spalling resistance is reduced. Decrease significantly.
[0061]
In addition, the metal reacts with the carbon in the refractory while hot to produce carbide, so that the carbon that is uniformly dispersed in the structure is consumed and lost, and after that, it is used for a long time at high temperatures thereafter. The problem which reduces the oversintering suppression effect at the time of use arises.
Therefore, it is desirable that the amount of metal added is not more than a certain level, preferably less than 4% by weight, more preferably less than 2% by weight.
[0062]
[Summary of each action and effect]
The above-described oversintering suppression and high modulus prevention means are naturally combined with each other, and the effect is further doubled, and the excellent “low carbonaceous carbon content is more stable due to the synergistic effect. Refractory "can be obtained.
[0063]
  As detailed above, the present invention provides:
・ Especially, pay attention to the systematic feature that the contact frequency of refractory raw materials made of low carbon materials becomes very high, and the "superfiring under high temperature" caused by the systematic feature. It provides an effective means to solve the problem of “adhesion progress and high elastic modulus”
-Different from the conventional technology accumulated in conventional high carbon materials, that is, different in technical idea,
・ In particular, it provides new organization control technology for materials in the low carbon region.
-And as a matter specifying the present invention, as at least a part of the carbonaceous raw material, an organic binder (fixed carbon content of 25 wt% or more and further having a viscosity of 200 poise or less, provided that it is outside this limited range Combination of organic binder is also included in the present invention), pitch (β-resin content is 10% by weight or more)) TheIt is characterized by being used in combination.
[0064]
[Description of raw materials that can be used in the present invention]
Next, the refractory raw material, carbonaceous raw material (including organic binder, pitch, and carbon black) and metal that can be used in the present invention will be specifically described.
[0065]
As the refractory raw material that can be used in the present invention, in addition to the above-mentioned magnesia, alumina, spinel, oxides such as calcia, dolomite, silica, chromia, zirconia, titania, and complex oxides thereof, or their coexisting raw materials Alternatively, generally used refractory raw materials such as electromelting raw materials, silicon carbide, silicon nitride, silicon oxynitride, boron nitride, boron carbide, zirconium boride, etc. can be arbitrarily used, all of which are included in the present invention. Is.
[0066]
The carbonaceous raw material used in the present invention includes “carbon raw material” and “organic raw material (organic binder, pitch, carbon black)” as described above.
[0067]
The carbon raw material that can be used in the present invention is not particularly limited, but is preferably one having a high fixed carbon content in order to maintain a high-temperature structure, that is, to ensure corrosion resistance, and natural graphite such as scaly graphite and earthy graphite is generally used. And artificial graphite such as coke, electrode scrap, carbon fiber, pyrolytic carbon, and the like.
[0068]
From the standpoint of preventing carbon pickup in the molten steel intended by the present invention, the blending ratio of the carbon raw material is the sum of the “fixed carbon content of the carbon raw material” and the “fixed carbon content of the organic raw material” and the refractory raw material. It is necessary to be “0.2-5% by weight” with respect to 100% by weight of the residual amount in the hotter than red heat of the total amount of carbonaceous raw material (meaning the total amount of refractory raw material components and fixed carbon). is there.
If it is less than 0.2% by weight, the effect of suppressing oversintering between refractory raw materials at high temperatures and the effect of suppressing slag infiltration cannot be sufficiently obtained. On the other hand, if it exceeds 5% by weight, carbon pick-up to molten steel becomes a problem. Therefore, it is not preferable.
[0069]
The organic binder used in the present invention is a liquid at room temperature.
Conventionally known resins such as phenol resins and furan resins can be used as the organic substance serving as the binder component. In addition, an aromatic organic polymer compound such as tar can be used, and is not particularly limited as long as it is sufficient to exert the effects of the present invention. Other natural or synthetic compounds Organic materials can also be used.
[0070]
The amount of the organic binder used in the present invention varies depending on the type of the refractory raw material, the type and amount of the carbon raw material, the purpose of use of the carbon-containing refractory of the present invention, and is not particularly limited. In the range not exceeding the fixed carbon content of “0.2 to 5% by weight”, generally from the viewpoint of the covering property to the constituent raw materials and the denseness of the hot structure, “1” with respect to 100% by weight of the solid raw material composition. ˜7 wt% ”is suitable.
[0071]
The pitch used in the present invention is not particularly limited, and for example, coal tar pitch, petroleum pitch, charcoal pitch, synthetic pitch, and the like can be used.
The amount of pitch used in the present invention varies depending on the type of refractory raw material, the type and amount of the carbon raw material, and the purpose of use of the carbon-containing refractory of the present invention, and is not particularly limited. In the range not exceeding “0.2 to 5% by weight”, from the viewpoint of diffusibility to the constituent raw materials and denseness of the hot structure, generally “0.1 to 7% by weight with respect to 100% by weight of the solid raw material composition % ”Is appropriate.
[0072]
The carbon black used in the present invention is not particularly limited. For example, any carbon black such as furnace black, channel black, lamp black, thermal black, and acetylene black can be used.
The amount of carbon black used in the present invention varies depending on the type of refractory raw material, the type and amount of the carbon raw material, and the purpose of use of the carbon-containing refractory of the present invention, and is not particularly limited. Within the range not exceeding "0.2 to 5% by weight", generally from the viewpoint of diffusibility to the constituent raw materials and filling properties during molding, "0.1 to 5% by weight with respect to 100% by weight of the solid raw material formulation % ”Is appropriate.
[0073]
Examples of the metal used in the present invention include silicon, aluminum, magnesium, titanium, chromium, calcium, and zirconium, or alloys and mixtures thereof.
As described above, the addition amount of the metal is desirably 4% by weight or less, preferably less than 4% by weight, and more preferably less than 2% by weight.
[0074]
[Description of the method for producing a low carbonaceous carbon-containing refractory of the present invention]
Next, the “method for producing a low-carbon carbon-containing refractory” according to the present invention will be described.
[0075]
In the present invention, first, a liquid binder and, if necessary, a metal or the like are further added to a raw material composition comprising the refractory raw material and the carbonaceous raw material (including a carbonaceous raw material that is solid at room temperature), and kneaded. Get the goblet.
At this time, carbonaceous raw material in an amount not exceeding 0.2 to 5% by weight of the fixed carbon content of the carbonaceous raw material with respect to 100% by weight of the hot residue of the raw material refractory including the refractory raw material and the carbonaceous raw material It is necessary to mix.
[0076]
Next, after the obtained clay is formed, it is baked at 120 to 400 ° C. to produce an “unfired carbon-containing refractory”. Moreover, operation for secondary raw material adjustments, such as granulation, coating, temporary forming, and crushing, can also be performed between these operations as needed.
The low carbonaceous refractory material obtained as described above can be baked in a reducing or non-oxidizing atmosphere of about 500 to 1500 ° C. to produce a “baked product”. It is included in the present invention.
[0077]
【Example】
  Next, an embodiment of the present inventionReference examples andThe low carbonaceous carbon-containing refractory and the method for producing the same according to the present invention will be described in more detail with reference to comparative examples.
[0078]
  Sample shown in Table 2 No. 1-18As for magnesia, alumina, and spinel (see Table 2 below), “mixture of electromelting raw material and sintered raw material” was used (grain size of “5 mm or less” was used). Further, scaly graphite (see Table 2 below) was used having a purity of 95% and a particle size of 0.1 mm or less. on the other hand,sample No. 1-18Table 1 shows the “organic binder, pitch” used in Table 1.
[0079]
[Table 1]

[0080]
(ExampleSamples for reference and comparative examples No. 1-18)
  Various raw materials were mixed and kneaded according to the “raw material mixture ratio (% by weight)” shown in Table 2 below, and then pressure-molded to a size of 230 × 114 × 65 mm at a pressure of 150 MPa. Next, this compact is baked at 200 ° C to produce a brick sample.No. 1-18It was created.
[0081]
“Porosity (apparent porosity after baking)” of the obtained sample is shown in Table 2. The obtained samples were measured for “elastic modulus (dynamic elastic modulus by impact method)” after reduction firing at 1500 ° C. for 20 hours, and the results are shown in Table 2.
Further, Table 2 shows the “compressive strength (MPa)” and the “spalling resistance index” after complete oxidation by heating at 1400 ° C. for 10 hours.
[0082]
The “Spalling Resistance Index” shown in Table 2 quantifies the number of cracks (number of cracks after thermal shock test) and the degree of damage that occur when a sample is immersed in hot metal at 1600 ° C according to certain rules. It is indexed after evaluation by the method (→ Refractory material, 44 [2] (1992), P75-82). The larger this value, the more it means "Excellent spalling resistance". Yes.
[0083]
  Sample shown in Table 2 No. Reference numerals 4, 8, 9, and 12 are examples of the present invention. No. Reference numerals 1-3, 5-7, 10, 11 are reference examples. Also sample No. 13 to 18 are comparative examples.
  In addition, with reference to Table 2, it is a comparative examplesample No. 13-18To explainsample No. 13 and 14 are samples. No. It is a comparative example for 1 and 2 (reference example), sample No. 15 and 16 are samples No. 3 (reference example ) , 4 (Example) comparative exampleIt is.
[0084]
  further,sample No. 17 is a sample No. 6 (reference example) is a comparative example and sample No. 18These are comparative examples for the low carbonaceous carbon-containing refractory of the present invention (fixed carbon content: 0.2 to 5% by weight).
[0085]
[Table 2]

[0086]
  As is clear from Table 2, it is a comparative examplesample No. 13-18In contrast to the low carbonaceous carbon-containing refractories of the present invention (sample No. 4, 8, 9, 12) Has a low porosity after baking and a dense product is obtained, and after low-temperature firing at a high temperature for a long time, the strength is kept low and excellent in spalling resistance, and at 1400 ° C It can be understood that the strength after complete oxidation is high, and it has excellent characteristics that can be used as a highly durable refractory even after oxidation.
[0087]
  That is, the low carbonaceous carbon-containing refractory of the present invention (sample No. 4, 8, 9, 12) Has significantly improved spalling resistance when heated for a long time compared to conventional products, and is dense and has high strength after oxidation. When it is used as a lining material for a steelmaking container, for example, it is clear that there is little carbon pickup to molten steel and high durability can be obtained.
  Further, as is apparent from Table 2, the low carbonaceous carbon-containing refractory of the present invention (sample No. 4, 8, 9, 12) are reference examples (samples) No. 1 to 3, 5 to 7, 10, and 11), it can be seen that the spalling resistance is particularly improved.
[0088]
【The invention's effect】
  As described in detail above, the present invention, in a raw material composition containing a refractory raw material and a carbonaceous raw material containing carbon, the fixed carbon content of the carbonaceous raw material with respect to 100% by weight of the hot residue of the raw material composition Is 0.2 to 5% by weight, and (a) to(D)This makes it possible to maintain good spalling resistance without excessive sintering even when used at high temperatures for a long time while having a dense structure. “High spalling resistance, It is possible to provide a low-carbon carbon-containing refractory material that has high corrosion resistance and can prevent carbon pickup to molten steel as much as possible.

Claims (7)

In a raw material composition including a refractory raw material and a carbonaceous raw material containing carbon, the carbonaceous raw material has a fixed carbon content of 0.2 to 5% by weight with respect to 100% by weight of the hot residue of the raw material composition. And at least a part of the carbonaceous raw material used was an organic binder having a fixed carbon content of 25% by weight or more and a viscosity of 200 poise or less, and a pitch having a β-resin content of 10% by weight or more. A low-carbon refractory material containing carbon. The low carbonaceous carbon-containing refractory according to claim 1, wherein carbon black is used in combination with at least a part of the carbonaceous raw material. The low carbonaceous carbon-containing refractory according to claim 1 or 2 , wherein magnesia, alumina, or spinel is used as at least a part of the refractory raw material. The low-carbonaceous carbon-containing refractory according to any one of claims 1 to 3 , wherein the raw material mixture contains a metal additive, and the content of the metal additive is 4% by weight or less. The low carbonaceous carbon-containing refractory according to any one of claims 1 to 4 , wherein the apparent porosity after baking is 4% or less. The low carbonaceous carbon-containing refractory of low carbonaceous according to any one of claims 1 to 5 compressive strength after being completely oxidized by heating at 1400 ° C. 10 hours is not less than 25MPa Refractories containing carbon. Carbon whose amount of fixed carbon of the carbonaceous raw material does not exceed 0.2 to 5% by weight with respect to 100% by weight of the hot residue of the raw material refractory including the refractory raw material and the carbonaceous raw material containing carbon A method for producing a low carbonaceous carbon-containing refractory according to any one of claims 1 to 6 , wherein a raw material is blended.