JP2003020268A - Magnesia-cobalt oxide-titania-alumina based clinker and refractory obtained by using the clinker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a basic refractory raw material which essentially consists of magnesia, and has excellent corrosion resistance, slag resistance, spalling resistance and slaking resistance, i.e., a magnesia-cobalt oxide-titania-alumina based clinker, and to provide refractories obtained by using the clinker. SOLUTION: A chemical composition consisting of, by weight, 50 to 95% magnesia, 0.2 to 20% cobalt oxide, 2 to 35% titania and 2.8 to 40% alumina is burned, or the one obtained by further blending glass components and/or a B2 O3 source material in a ration of 0.2 to 3 pts.wt. per 100 pts.wt. of the same composition is burned, so that the objective clinker is obtained.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a magnesia-cobalt oxide-titania-alumina clinker and a refractory material obtained by using the clinker, and in particular, a container for molten steel, a container for refining furnace, or cement, lime, etc. in the ironmaking industry. The present invention relates to a refractory material for a lining in a kiln or the like, an amorphous refractory material such as castable or spraying material, and a raw material for a basic refractory material used as a repair material.

[0002]

BACKGROUND ART Conventionally, in the field of steelmaking and non-ironmaking,
Metal oxides such as alumina, spinel, magnesia, zirconia, and silica have been widely used as refractory materials. Among them, magnesia is used as a main raw material for basic refractory materials because of its excellent corrosion resistance. Has been done.

However, although such a magnesia-based refractory material has excellent corrosion resistance, it has the disadvantages of large thermal expansion, poor spalling resistance, significant slag wetting, and easy digestion. Since it is inherent, magnesia refractory materials have the problem of life shortening due to spalling due to thermal stress and structural spalling due to slag wetting. However, there is a drawback that it is difficult to use in places where

However, the spalling due to the thermal stress and the structural spalling due to the slag wetting have been solved by a combination of magnesia and carbon, which is used as a magnesia-carbon brick in a converter, a molten steel ladle and the like. ing. However, this magnesia-carbon brick emits carbon dioxide, which is a source of global warming, during its use, and therefore, as a refractory in the future considering the environment, the brick contains a big problem. I have to say that.

Further, in order to improve the digestion resistance of magnesia, it is possible to add silica such as silica flour, which is widely adopted. However, the addition of such silica forms a low melting point compound. However, since the corrosion resistance is deteriorated, the amount added is limited, and there is a problem that the improvement of digestion resistance is also limited.

In addition to the above, a basic refractory in which titania or the like is added to magnesia has been reported. For example, in JP-A-9-2055, a magnesia-calcia-titania basic refractory is clarified. In addition, Japanese Patent Laid-Open No. 58-1593 discloses a sintered body in which aluminum titanate is added to spinel. Further, Japanese Patent Laid-Open No. 49-6008 discloses magnesia-titania-
Alumina-zirconia refractories have been proposed.

However, the method of adding titania or alumina to magnesia is considered to be an effective means because it has the function of improving the spalling property due to thermal stress by forming a solid solution of magnesia-alumina spinel and magnesium titanate. However, when used as a refractory, there is a drawback that titania reacts with iron oxide or silica on the working surface, which is the surface that comes into contact with the molten metal or slag, to lower the corrosion resistance.

Further, in particular, calcia contained as an impurity in magnesia reacts with the added titania,
Although it is expected to generate perovskite and thereby improve digestion resistance, since the content of calcia as an impurity is low, less perovskite is produced, and therefore improvement in digestion resistance can be sufficiently satisfied. It wasn't something.

[0009] In addition, the calcia in the slag reacts with the added titania to form the above-mentioned perovskite and forms a dense layer on the operating surface to improve the slag resistance. As mentioned above, from the point of reacting with silica and iron oxide over time,
There is an inherent problem that causes a reduction in corrosion resistance.

[0010]

The present invention has been made in view of such circumstances, and the problem to be solved is to have excellent corrosion resistance, slag resistance, and spalling resistance. To provide a basic refractory raw material containing magnesia as a main component, that is, magnesia-cobalt oxide-titania-alumina clinker, and a refractory obtained using the same. is there.

[0011]

In order to solve such a problem, the present invention solves the problem by magnesia: 50 to 95% by weight, cobalt oxide:
Magnesia characterized by comprising a fired product obtained by firing a composition giving a chemical composition of 0.2 to 20% by weight, titania: 2 to 35% by weight, and alumina: 2.8 to 40% by weight. -Cobalt oxide-titania-alumina clinker is the subject.

As described above, the basic refractory raw material clinker according to the present invention is mainly composed of magnesia which is excellent in corrosion resistance, and is composed of cobalt oxide together with titania and alumina. , In particular, by using cobalt oxide together, it forms a high melting point spinel with alumina and a high melting point solid solution with magnesia, which contributes to the improvement of corrosion resistance and, with respect to titania, its chemical By improving the stability, it was possible to make a great contribution to the improvement of properties such as corrosion resistance, digestion resistance, spalling resistance, and slag resistance.

In the magnesia-cobalt oxide-titania-alumina clinker according to the present invention, the glass component is preferably 0.2 to 3 parts by weight based on 100 parts by weight of the composition. It will be further compounded. By further blending such glass components, it is possible to advantageously contribute to the improvement of digestion resistance.

According to another preferred embodiment of the present invention, the B ₂ O ₃ source material is further added in an amount of 0.2 to 3 parts by weight based on 100 parts by weight of the composition. In this case, the digestion resistance can be further improved.

Further, the present invention provides a clinker according to the above-mentioned present invention, that is, a composition which gives a predetermined chemical composition of magnesia, cobalt oxide, titania and alumina, or a predetermined proportion of glass component and / or B ₂ O. A refractory characterized by using a magnesia-cobalt oxide-titania-alumina clinker consisting of a fired product obtained by firing a mixture of _three- source materials as a refractory material, and its summary It is what

Even in such a refractory material according to the present invention, the above-mentioned characteristics of the clinker according to the present invention can be directly exerted.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the magnesia-cobalt oxide-titania-alumina clinker according to the present invention, magnesia must be contained in a proportion of 50 to 95% by weight. This is because if the content of magnesia is less than 50% by weight, the effect of imparting high melting point and corrosion resistance by magnesia cannot be sufficiently exerted, and if it exceeds 95% by weight, other components (cobalt oxide, This is because the content ratio of titania and alumina) is reduced, and it becomes difficult to obtain a clinker having the desired characteristics.

Further, titania and alumina to be combined with such magnesia must have chemical compositions of 2 to 35% by weight and 2.8 to 40% by weight, respectively, but the effect of adding these components is sufficient. 2% by weight of titania and 2.8% by weight of alumina
It is necessary to set the above content. In addition, a part of titania reacts with magnesia to form magnesium titanate, while alumina reacts with magnesia, resulting in magnesia.
Produces alumina spinel. Then, the spinel thus formed forms a solid solution with magnesium titanate, but in this case, if the amount of titania is too much, the magnesium titanate that is a low melting point increases, and the solid solution with spinel is also biased to magnesium titanate. It becomes a composition, and the corrosion resistance comes to deteriorate. Therefore, the upper limit of the titania content is preferably 35% by weight, and the alumina content is 40% by weight corresponding to the titania content.
The following is desirable.

Further, cobalt oxide which constitutes the clinker according to the present invention together with magnesia, titania and alumina forms a spinel having a melting point of 1900 ° C. or higher with alumina, and has a melting point of 180 with magnesia.
It forms a solid solution at 0 ° C. or higher, which contributes to the improvement of corrosion resistance and, in addition to titania, imparts excellent chemical stability according to the behavior assumed below.

That is, titania is a non-stoichiometric substance, and the ratio of cation to anion is not exactly 1: 2 as represented by the composition formula: TiO ₂ . In titania, the titanium atom, which is a cation, is present in excess, and the titanium atom originally invades into a place other than the position of the titanium atom. Also, the amount of excess titanium atoms has the property of decreasing with increasing oxygen pressure and increasing with decreasing oxygen pressure.

On the other hand, cobalt oxide is also a non-stoichiometric substance like titania, and its properties are exactly the opposite of those of titania, and it is in the form of lacking cations. The degree of atomic deficit increases with increasing oxygen pressure and decreases with decreasing oxygen pressure.

Therefore, by utilizing the properties of the titania and cobalt oxide, by combining the titania and cobalt oxide, the exchange of oxygen as an anion is carried out between the titania and cobalt oxide by the following formula: TiO _{2 -α} + 2CoO _{1 + β} = 2CoO · TiO ₂ + O
It is thought that this is caused in the form shown by _β-α , and thus stable titania and cobalt oxide are realized regardless of the surrounding oxidizing or reducing atmosphere.

[0023] Cobalt oxide having such characteristics has a content of at least 0, because if its content is too small, the effect of its addition cannot be fully exhibited.
It is necessary to contain 2% by weight or more. However, increasing the addition amount (content) of such cobalt oxide is
Since cobalt oxide itself is a very expensive substance, it is not a good idea in terms of cost efficiency.
It is contained in an amount of not more than 10% by weight, preferably not more than 10% by weight.

By the way, in the clinker according to the present invention, after magnesia, cobalt oxide, titania, and alumina are provided in the chemical compositions as described above, the raw materials of the respective components are blended to prepare a composition. Although it can be obtained by firing, various known materials can be used as the raw material of each component for preparing such a composition. For example, as the magnesia source material, natural magnesia, seawater magnesia, magnesia clinker and magnesium hydroxide produced by various known manufacturing methods, electro-dissolved magnesia, etc. may be used,
Further, as the cobalt oxide source material, cobalt monoxide,
Cobalt trioxide, cobalt tetraoxide, cobalt oxalate hydrate, cobalt stearate, cobalt sulfate, cobalt sulfide and the like can be used. Further, rutile type or anatase type titania can be used as the titania source material, and calcined alumina or sintered alumina can be used as the alumina source material.

In addition, in the composition (magnesia + cobalt oxide + titania + alumina) which gives the chemical composition according to the present invention, a predetermined glass component is preferably added in an amount of 0.1% by weight to 100 parts by weight of the composition. It will be further compounded in the proportion of 2 to 3 parts by weight. The compounding of such a glass component is to form a glass phase in magnesia by firing and coat the surface of periclase to enhance digestibility. If the blending amount of the glass component is less than 0.2% by weight, the effect is not obtained, and 3% by weight
If it exceeds, the glass phase will increase and the corrosion resistance will decrease. Also, as this glass component,
Specifically, known materials such as silicate glass, borate glass, and phosphate glass can be appropriately used.

A B ₂ O ₃ source material may also be used in combination with the glass component, or in place of the glass component, in the composition.
In a ratio of 0.2 to 3 parts by weight with respect to 00 parts by weight,
It will be further compounded. B ₂ O ₃ like this
The source material is that provided by boric acid, borax, etc., which reacts with magnesia to produce 3MgO.B.
_It forms ₂ O ₃ and contributes to the improvement of digestion resistance.
If the blending amount is less than 0.2% by weight, there is no effect. On the contrary, if the blending amount exceeds 3% by weight, the B ₂ O ₃ source material is also a glass component, resulting in deterioration of corrosion resistance. For this reason, it is desirable to mix the compound within the range of 0.2 to 3% by weight.

In producing the magnesia-cobalt oxide-titania-alumina clinker according to the present invention, first, a composition giving the above-mentioned chemical composition, or a glass component and / or a B ₂ O ₃ source material is added thereto. Is prepared, and then water is added thereto to form a slurry, which is then dehydrated and extruded, or a binder is added to the above-mentioned preparation and kneaded, followed by molding with a briquette machine. After that, according to the normal firing operation,
By firing at a temperature of about 1500 to 2000 ° C., the target clinker can be obtained as a fired product.

As the binder used in the production of such clinker, various known binders can be mentioned, for example, lignins, starches, polyvinyl alcohol, methyl celluloses, various phenol resins, molasses, etc. Used in proportions, it will be advantageously shaped into the desired shape.

In the refractory material according to the present invention, the clinker as described above is used as a refractory material, and it is advantageously formed by the following method.

That is, first, the clinker according to the present invention described above is pulverized and sized according to a conventional method to obtain a refractory material consisting of powder or granules of the clinker, and then obtaining the refractory material. A molded refractory material such as bricks is obtained by molding the obtained refractory material into a predetermined shape by a conventionally known method, and then heating and sintering it as required.

As another method, various cements, binders, and the like are mixed with the refractory material of the clinker according to the present invention obtained as described above, and the powder or the kneaded clay indefinite shape is mixed. There are ways to obtain refractories. In addition, in this amorphous refractory, as is well known,
After that, water is added and a molding operation such as a stamp molding method or a vibration molding method is carried out, whereby a refractory product having a desired shape is formed.

As described above, the refractory material according to the present invention can be advantageously manufactured as a regular refractory material or an irregular refractory material in any shape, and moreover, such refractory material can be manufactured. As described above, it has excellent corrosion resistance, slag resistance, spalling resistance, and digestion resistance.

[0033]

EXAMPLES Some experimental examples including typical examples of the present invention will be shown below to clarify the present invention in more detail. However, the present invention is not limited to such experimental examples. It goes without saying that the description does not impose any restrictions. In addition to the following embodiments, the present invention further includes various changes and modifications based on the knowledge of those skilled in the art, in addition to the above specific description, without departing from the spirit of the present invention. It should be understood that improvements and the like can be added.

Experimental Example 1 As a raw material, magnesium hydroxide was used as a magnesia source material, and cobalt oxide, titania (rutile flower), and calcined alumina were further used.
In various proportions shown in (however, magnesium hydroxide is converted to magnesia), after adding polyvinyl alcohol as a binder together with water, and kneading, and then molded in a briquette machine, The obtained molded product is heated at a temperature of 150 ° C. for 10 minutes.
Allow to dry for a while, then 1 in a rotary kiln
Various clinker (baked products) were obtained by baking at a temperature of 600 ° C. Then, with respect to various clinker made of the obtained fired product, respective properties, that is, apparent porosity, digestion resistance, spalling resistance and slag resistance were examined, and the results are also shown in Table 1 below. .

The porosity in the characteristic evaluation of the clinker is as follows.
The physical properties of the particles sieved to 3.36 to 2.38 mm, measured according to JIS-R-2205,
Digestion resistance was obtained by using particles of 1 mm or less in water vapor under a pressure of 3 atm.
Shown as weight gain after autoclaving at a temperature of 1 ° C. for 3 hours, and the spalling resistance is 1000, with particles of 3.36-2.38 mm.
This is shown as the generation rate (pulverization rate) of powders of 2.38 mm or less when the operation of heating in water at 30 ° C. for 30 minutes and then throwing in water is repeated three times.

The slag resistance is 60% by weight of the particles of 1 mm or less of each clinker, and the mill powder (325
40% by weight of a clinker powder having a particle size of less than or equal to μm is kneaded with an aqueous solution of polyvinyl alcohol, and then molded into a predetermined shape, which is obtained by firing at a temperature of 1650 ° C. On the fired product of such a molded body, a slag having a composition of iron: 60% by weight, lime: 30% by weight, and silica: 10% by weight is placed,
It is shown as a result of evaluation by the slag penetration depth (mm) obtained by conducting a slag penetration experiment under the condition of 1600 ° C. × 2 hours.

[0037]

[Table 1]

As is clear from the results of Table 1, N
o. In the experiment of No. 1, since the raw material composition containing no cobalt oxide was adopted, the clinker obtained had poor digestion resistance. On the other hand, No. In the experiments of 2 or less, the improvement of the digestion resistance of the obtained clinker is recognized due to the inclusion of cobalt oxide. In addition, No. 1 containing a large amount of cobalt oxide was added. In the experiment of No. 6, the porosity was high, and as a result, the degradation of digestion resistance was observed. In the experiment of No. 7, the production of magnesium titanate increased, and the spalling resistance decreased. In addition, no. In the experiment of 8, the spinel production increased, the porosity increased, and
It is recognized that the slag resistance and spalling resistance are reduced.

Further, using various clinker shown in Table 1 above, each crushed, molded and fired according to a conventional method to produce various bricks, and the physical properties of each brick were evaluated. Results similar to 1 were obtained.

Experimental Example 2 In addition to the four raw material components in Experimental Example 1, phosphate glass was further used as a glass component in various compounding compositions shown in Table 2 below (however, the glass component is four raw materials). Calcination was carried out in the same manner as in Experimental Example 1 to obtain the desired clinker. The phosphate glass is silica: 0.7% by weight, alumina: 18.8% by weight, lithium oxide: 7.9.
% By weight, sodium oxide: 20.8% by weight, boric acid: 9
It had a composition of wt% and phosphoric acid: 34 wt%. And about this various clinker obtained,
In the same manner as in Experimental Example 1, the apparent porosity, digestion resistance, spalling resistance and slag resistance were evaluated. The results are also shown in Table 2 below.

[0041]

[Table 2]

As is clear from the results of Table 2, in addition to the essential four components of magnesia, cobalt oxide, titania and sintered alumina, a predetermined amount of phosphate glass should be added and contained as a glass component. It can be acknowledged that the effect of further improving the digestion resistance can be exhibited. However, if the added amount increases, N
o. As shown in the experiment of No. 13, it is recognized that the slag resistance is lowered.

Experimental Example 3 As the clinker raw material, the same magnesia, cobalt oxide, titania, and calcined alumina as in Experimental Example 1 were used, and further boric acid was used as the B ₂ O ₃ source material.
Firing was carried out in the same manner as in Experimental Example 1 at various blending ratios with different boric acid blending amounts shown in Table 3 below (however, boric acid is used by externally applying to four raw material components). , Various kinds of clinker were obtained. Then, for each of the obtained clinker, in the same manner as in Experimental Example 1,
Apparent porosity, digestion resistance, spalling resistance, and slag resistance were evaluated, and the results are also shown in Table 3 below.

[0044]

[Table 3]

From the results shown in Table 3, it is recognized that the digestion resistance improves as the amount of boric acid added increases. However, no. From the results of the 18 experiments, it is recognized that the slag resistance is lowered when the addition amount of boric acid is increased.

Experimental Example 4 A rotary kiln was used for firing in the same manner as in Experimental Example 1 except that a raw material composition having the composition shown in Table 4 below was used and the firing temperature was changed as shown in Table 4 below. The desired clinker was obtained. Then, the obtained clinker was evaluated for apparent porosity, digestion resistance, spalling resistance, and slag resistance in the same manner as in Experimental Example 1.
The results are also shown in Table 4 below.

[0047]

[Table 4]

From the results shown in Table 4, it is recognized that by increasing the firing temperature, the apparent porosity of the clinker, which is a fired product, is lowered, and the digestion resistance can be improved. However, if the firing temperature becomes too high,
No. As shown in the experiment of No. 22, the spalling resistance is deteriorated.

[0049]

As is apparent from the above description, the magnesia-cobalt oxide-titania-alumina clinker according to the present invention contains magnesia, which is excellent in corrosion resistance, as a main component, and cobalt oxide, titania and alumina are added to the main component. In particular, cobalt oxide is used to improve the chemical stability of titania by using it together, which makes it excellent in corrosion resistance, slag resistance, and spalling resistance. A basic refractory raw material having excellent properties and excellent digestion resistance could be realized.

Further, even a refractory obtained by using such a clinker inherits the characteristics of the clinker as a raw material as it is, and therefore has excellent characteristics not only in corrosion resistance but also in slag resistance, spalling resistance and digestion resistance. As a refractory for various applications, for example, a molten steel container, a refining furnace container, a refractory for lining such as baked giraffe, or an amorphous refractory such as castable or spraying material, repair It can be advantageously used as a basic refractory used for materials and the like.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toyoyasu Obana             4 Itochu, 11 Shiogusa-cho, Seto City, Aichi Prefecture             Within LATEC Co., Ltd. (72) Inventor Hiroshi Makino             4 Itochu, 11 Shiogusa-cho, Seto City, Aichi Prefecture             Within LATEC Co., Ltd. (72) Inventor Masato Mori             4 Itochu, 11 Shiogusa-cho, Seto City, Aichi Prefecture             Within LATEC Co., Ltd. F-term (reference) 4G030 AA07 AA16 AA28 AA35 AA36                       BA23 BA25                 4G033 AA03

Claims (4)

[Claims] 1. A composition giving a chemical composition of magnesia: 50-95% by weight, cobalt oxide: 0.2-20% by weight, titania: 2-35% by weight, and alumina: 2.8-40% by weight. A magnesia-cobalt oxide-titania-alumina clinker comprising a fired product obtained by firing. 2. The magnesia-cobalt oxide-titania-alumina according to claim 1, wherein the glass component is further compounded in a ratio of 0.2 to 3 parts by weight with respect to 100 parts by weight of the composition. System clinker. 3. A B ₂ O ₃ source material is 100% of said composition.
The magnesia-cobalt oxide-titania-alumina clinker according to claim 1 or 2, which is further compounded in a proportion of 0.2 to 3 parts by weight relative to parts by weight. 4. A refractory material comprising the magnesia-cobalt oxide-titania-alumina clinker according to any one of claims 1 to 3 as a refractory material.