JP2019137561A - Monolithic refractory composition - Google Patents

Abstract

To provide a monolithic refractory composition that can be rapidly heated, is easily disassembled, and is useful for forming a monolithic refractory excellent in impact resistance.SOLUTION: One embodiment of this invention comprises a monolithic refractory composition containing aggregate, binder, alumina fine powder, organic fiber, and boron-based antioxidant. Another embodiment of this invention comprises a monolithic refractory composition containing aggregate, binder, alumina fine powder, colloidal silica, and boron-based antioxidant. As described above, a monolithic refractory composition having desired characteristics can be obtained by containing a predetermined combination of components such as organic fiber and boron-based antioxidant or colloidal silica and boron-based antioxidant.SELECTED DRAWING: None

Description

  The present invention relates to an amorphous refractory composition, and more particularly, to an amorphous refractory composition suitable for forming a refractory having resistance to rapid temperature rise and having good dismantling and impact resistance.

  The amorphous refractory is a refractory that is formed by on-site construction, but is generally mixed with alumina cent for hardening. However, although alumina cent has high heat resistance in cement, it has lower heat resistance than other refractory aggregates. In addition, alumina cement has high reactivity with slag and other processed materials in the furnace, and has been a cause of lowering the corrosion resistance of the refractory.

  In order to reduce the influence of such problems, low cement type amorphous refractories that reduce the content of alumina cement and promote agglomeration of ultrafine powder through a small amount of alumina cement are known (for example, patents) Reference 1).

  In addition, an amorphous refractory that does not use any alumina cement has also been studied. For example, an amorphous refractory composition in which active magnesia (MgO) is blended without using alumina cement as a curing agent in an amorphous refractory composition. It is known (see Patent Documents 2 to 4).

  Furthermore, the powder composition for amorphous refractories that can form refractories with excellent stability without using alumina cement, while using aggregates with relatively high stability and corrosion resistance A thing is also known (for example, refer patent document 5).

JP 11-199334 A Japanese Examined Patent Publication No. 6-33179 JP-A-7-223874 JP-A-9-263457 JP 2011-47563 A

  By the way, when it is used as a lining material for a melting furnace (especially a melting furnace used for melting aluminum or aluminum alloys), it can be rapidly heated, easily disassembled, and has good impact resistance. However, conventionally, there is no known amorphous refractory material that satisfies all of these characteristics.

  Therefore, the present invention aims to solve the above-mentioned problems, and to provide an amorphous refractory composition that can form an amorphous refractory that can be rapidly heated, has easy disassembly, and has excellent impact resistance. To do.

  The amorphous refractory composition of the present invention comprises an aggregate, a binder, fine alumina powder, organic fibers, and a boron-based antioxidant.

  Another amorphous refractory composition of the present invention is characterized by containing an aggregate, a binder, fine alumina powder, colloidal silica, and a boron-based antioxidant.

  According to the amorphous refractory composition of the present invention, it is possible to form an amorphous refractory that can be rapidly heated, easily disassembled, and excellent in impact resistance. Thereby, the start-up time of the melting furnace can be increased by shortening the drying time, blackening of the refractory when aluminum or aluminum alloy is melted can be suppressed, and a refractory with good compressive strength can be obtained.

Hereinafter, the present invention will be described in detail with reference to an embodiment.
[First Embodiment]
As described above, the amorphous refractory composition of the present embodiment includes aggregate, binder, fine alumina powder, organic fiber, and boron-based antioxidant.
(aggregate)
Aggregate used in the present embodiment, if the aggregate which has been used in the manufacture of conventional monolithic refractories can be used without particular limitation, for example, alumina (Al 2 O _3), zirconia (ZrO ₂ ), Zircon (ZrO ₂ · SiO ₂ ) and the like. Alumina is preferably used because the refractory has excellent hot stability and corrosion resistance.

As alumina used here, chamotte (Al ₂ O ₃ : 40 to 50% by mass), mullite (Al ₂ O ₃ : around 60% by mass), bauxite (Al ₂ O ₃ : 80 to 89% by mass), high purity alumina _{(Al 2} O 3: 90 wt% or higher), and the like. It is preferable to use high-purity alumina because the higher the alumina content in the aggregate, the better the corrosion resistance.

  The most preferred aggregate is high-purity alumina having an alumina content of 90% by mass or more. This high-purity alumina can be produced by electromelting or sintering alumina. Among them, high-purity alumina having an alumina content of 99% by mass or more is most preferable as a refractory.

  This aggregate preferably has a particle size of 45 μm to 5 mm. If the particle size is larger than 5 mm, the kneaded soil may not be well-organized and a lump may not be formed. When it becomes larger, the flow becomes worse and the workability is lowered.

  Also in the above range, it is preferable to use aggregates having different sizes in combination. For example, it can be divided into categories having different sizes such as 3 mm or more and less than 5 mm, 1 mm or more and less than 3 mm, 45 μm or more and less than 1 mm, and less than 45 μm, and these can be used in appropriate combinations. As a preferable combination, when all aggregates are 100% by mass, aggregates of 3 mm or more and less than 5 mm are 15 to 30% by mass, aggregates of 1 mm or more and less than 3 mm are 15 to 30% by mass, 45 μm or more and less than 1 mm. In terms of filling clay, it is preferable to set the aggregate to 15 to 30% by mass and the aggregate of less than 45 μm to 15 to 30% by mass. In addition, in this specification, a particle size says the value measured according to JISR2552.

  The mixing ratio of the aggregate is 72 to 97% by mass, preferably 75 to 95% by mass in the amorphous refractory composition. When the proportion of the aggregate is less than 72% by mass, the strength and corrosion resistance of the obtained refractory cannot be sufficiently obtained. Conversely, when it exceeds 97% by mass, sufficient fluidity necessary for construction is obtained. Absent.

(Binder)
As the binder used in the present embodiment, a known binder can be used as long as the binder is a low cement, and aggregates are bonded to each other by the action of these components to form a dense structure. Examples of the binder include a combination of high alumina cement, active magnesia, low-reactivity alkaline earth metal oxide, and water-soluble organic acid salt or inorganic acid salt.

  This binder is preferably a fine powder having an average particle size of less than 40 μm, and more preferably less than 5 μm. The average particle size of the binder is particularly preferably 1 μm or less in terms of compressive strength during curing. Moreover, in this specification, an average particle diameter means what was computed by the laser diffraction type particle size distribution measuring method.

  The blending ratio of the binder is 1 to 11% by mass, preferably 2 to 10% by mass in the amorphous refractory composition. When the blending ratio of the binder is less than 1% by mass, the aggregates are not sufficiently bonded to each other, and the strength and corrosion resistance of the refractory cannot be sufficiently obtained. Conversely, when it exceeds 11% by mass, the structure is dense. It becomes too much and breakage such as explosion tends to occur at the time of rapid temperature rise.

(Alumina fine powder)
The alumina fine powder used in the present embodiment may be any alumina fine powder conventionally used in an amorphous refractory composition, and its own cohesive strength is strong. When the amorphous refractory composition is used as a refractory, it is hardened. It has a promoting action. At this time, the alumina fine powder having an average particle size of less than 10 μm can be used from the viewpoint of accelerating the hardening of the refractory due to aggregation thereof, and is preferably less than 5 μm.

  Silica fine powder can also be added to these components. At this time, silica fine powder should just be silica fine powder conventionally used for the amorphous refractory composition, and hardening of a powder composition can be accelerated | stimulated more by using together alumina fine powder and silica fine powder. . The silica fine powder preferably has an average particle size of less than 10 μm, and more preferably less than 1 μm.

  The mixing ratio of the alumina fine powder is 1 to 11% by mass, preferably 2 to 10% by mass in the amorphous refractory composition. If the blending ratio of the alumina fine powder is less than 1% by mass, the aggregates are not sufficiently bonded to each other, and the strength and corrosion resistance of the refractory cannot be sufficiently obtained. Conversely, if it exceeds 11% by mass, the structure is dense. It becomes too much and breakage such as explosion tends to occur at the time of rapid temperature rise.

  Further, when silica fine powder is blended, the blending amount of the fine alumina powder and the fine silica powder is preferably in the range of the fine alumina powder.

(Organic fiber)
As the organic fiber used here, polypropylene fiber, polyethylene fiber, polyester fiber, polyvinyl alcohol fiber, cellulose fiber and the like can be used. By containing this organic fiber, when the refractory obtained from the amorphous refractory composition is rapidly heated, moisture and the like inside the refractory can escape and damage such as explosion can be prevented.

  As the organic fiber, one having a fiber length of 10 μm to 20 mm and a fiber diameter of 0.1 to 20 dtex can be used. Here, the fiber length is preferably 100 μm to 10 mm, and the fiber diameter is preferably 0.5 to 15 dtex.

  Moreover, it is preferable to use together 2 or more types of organic fiber from which fiber length differs as an organic fiber. By using two or more kinds of organic fibers in this way, explosion is prevented, and when refractory construction is performed, when the amorphous refractory composition is mixed with water to form clay, the fluidity is good. And can. In order to exhibit such an effect | action well, as an organic fiber, fiber length 3mm-20mm, fiber diameter 0.1-20dtex long fiber, fiber length 10micrometer-3mm, fiber diameter 0.1-20dtex short It is preferable to use a fiber together.

  In addition, when using together the above-described long fiber and short fiber as the organic fiber, the blending ratio (long fiber / short fiber) on a mass basis of the long fiber and the short fiber in the organic fiber is 1/1. It is preferable to set to ~ 1/5.

  The blending ratio of the organic fiber is 0.005 to 0.5 mass%, preferably 0.01 to 0.4 mass% in the amorphous refractory composition. If the blending ratio of the organic fiber is less than 0.005% by mass, sufficient resistance to rapid temperature rise cannot be obtained, and conversely if it exceeds 0.5% by mass, sufficient fluidity required for construction is obtained. I can't.

(Boron-based antioxidant)
Examples of the boron-based antioxidant used in the present embodiment include zirconium boride, boron carbide, calcium boride and the like, and are components that also act as a sintering aid.
By containing these boron-based antioxidants, the sintering of the amorphous refractory is promoted, and when used as a lining material of a melting furnace, for example, at an operating temperature of 700 to 1300 ° C., the strength is improved. Can do. Moreover, a liquid phase oxide film is formed on the surface of the refractory that can exhibit good oxidation resistance, and good oxidation resistance can also be exhibited. Therefore, the effect | action which improves blackening can be provided and it can use favorably also for the fusion | melting of aluminum or aluminum alloy.

  The mixing ratio of the boron-based antioxidant is 0.01 to 10% by mass, preferably 0.05 to 8% by mass in the amorphous refractory composition. When the boron carbide content is less than 0.01% by mass, the amount of the boric acid melt produced by oxidation decreases, and the oxide film has a sufficient thickness on the refractory surface and the inner surface of the open pores of the refractory. Cannot be formed, resulting in inferior oxidation resistance and corrosion resistance. On the other hand, if it exceeds 10% by mass, the amount of the boric acid melt produced by oxidation becomes too large, resulting in poor corrosion resistance.

  Furthermore, in addition to the above-described components, additives such as a dispersant and a digestion inhibitor can be used as appropriate as long as the effects of the present invention are not impaired.

  Examples of the dispersant that can be used here include surfactants and AE agents, and examples of the digestion inhibitor include aluminum lactate and aluminum glycolate.

  In addition, when the dispersant and digestion inhibitor are blended, the blending amount thereof is 100% by mass as the total blending amount of the aggregate, binder, alumina fine powder, organic fiber, and boron-based antioxidant, respectively. In contrast, those containing 0.001 to 10% by mass and 0.01 to 8% by mass on the outside are preferable.

  The amorphous refractory composition of the present embodiment can be produced by sufficiently uniformly mixing the above components. The powder composition thus obtained is kneaded with water to form a clay, and cast and sprayed to form the refractory at a desired location and shape. Can be manufactured.

[Second Embodiment]
As described above, the amorphous refractory composition of the present embodiment includes aggregate, binder, fine alumina powder, colloidal silica, and boron-based antioxidant.
The second embodiment is different from the first embodiment in that organic fiber is not blended as an essential component and colloidal silica is essential. Since the other components are the same as those in the first embodiment, only the differences will be described below.

(Colloidal silica)
The colloidal silica used in the present embodiment is silica on a sol, preferably having a silica solid content concentration of 10% by mass to 50% by mass, and a silica solid content concentration of 20% by mass to 50% by mass. Are more preferred.

  1-11 mass% is preferable in an amorphous refractory composition, and, as for the quantity of this silica solid content derived from colloidal silica, 2-10 mass% is more preferable.

Moreover, colloidal silica makes a hardening body by gelatinizing by addition of a hardening | curing agent, and provides sufficient shape retention property and intensity | strength to an amorphous refractory. In this embodiment, the curing agent of colloidal silica, as mentioned in the basic magnesium carbonate _{(xMgCO 3 · yMg (OH)} 2 · zH 2 O), and magnesium carbonate raw material containing MgCO _3.

  The reason for using the magnesium carbonate raw material as the curing agent is as follows. In the case of using a magnesium carbonate raw material, it is considered that the curing proceeds more slowly because magnesium ions are eluted more slowly into the matrix of the amorphous refractory than in the case of using magnesia fine powder. When the curing reaction proceeds rapidly, a strength gap between the cured portion and the uncured portion is generated, and it is considered that shrinkage occurs due to the strength gap. For this reason, it is considered that magnesium ions are gradually eluted into the matrix, so that a strength gap with a portion that is not hardened hardly occurs, and shrinkage due to the strength gap hardly occurs. Therefore, it is considered that the use of a magnesium carbonate-based raw material has an effect of reducing curing shrinkage as compared with magnesia fine powder.

  The amount of the magnesium carbonate raw material added as the curing agent is suitably defined in relation to the amount of silica solids of colloidal silica as the binder. In this embodiment, the mass ratio of the magnesium carbonate raw material to the mass of the silica solid content derived from colloidal silica (magnesium carbonate raw material / silica solid content) was set to 0.001 or more and 4 or less. When this mass ratio is less than 0.001, curing delay occurs and the curing strength cannot be ensured. On the other hand, when this mass ratio is larger than 4, there are problems of instantaneous coupling and swelling. Preferably, it is 0.005 or more and less than 0.5.

  In the present embodiment, a fire-resistant composition capable of forming an amorphous refractory having an easy-to-disassemble property and excellent impact resistance can be obtained by adopting such a configuration.

  As described above, the amorphous refractory composition described in the first and second embodiments can be rapidly heated, is easily disassembled, and is an amorphous refractory excellent in impact resistance. It is useful for forming and is suitable as an amorphous refractory material to be constructed as a lining material for a melting furnace.

  In addition, as a characteristic of the amorphous refractory obtained using the amorphous refractory composition obtained by the above embodiment, it is preferable to satisfy the following conditions.

As the refractory material that can withstand rapid temperature rise, those that do not explode when the rate of temperature rise is 60 ° C./hour or more, preferably 150 ° C./hour or more, more preferably 200 ° C./hour or more are preferred. Whether or not explosion has occurred can be evaluated, for example, by measuring the internal water vapor pressure when the amorphous refractory sample is heated, and the internal water vapor pressure only needs to be 10 kg / cm ² or less.

  The refractory can be easily disassembled (≈difficult to blacken) by, for example, performing an erosion test using molten aluminum and evaluating the spread of blackening. Here, the erosion test can be performed by placing an aluminum alloy in a crucible sample of an irregular refractory, firing at 850 ° C. for a predetermined time, and immersing molten aluminum.

  The impact resistance of the refractory can be evaluated by, for example, compressive strength at 1200 ° C. Here, the compressive strength can be measured for an amorphous refractory sample under heating conditions of 1200 ° C. according to JIS R 2553, preferably 150 MPa or more, and more preferably 170 MPa or more.

  By satisfying all of the above characteristics, it is suitable as an amorphous refractory used as a lining material for a melting furnace of aluminum or aluminum alloy.

Claims (5)

  An amorphous refractory composition comprising an aggregate, a binder, alumina fine powder, organic fibers, and a boron-based antioxidant.   The amorphous refractory composition according to claim 1, wherein the organic fiber has a fiber length of 10 μm to 20 mm and a fiber diameter of 0.1 to 20 dtex.   An amorphous refractory composition comprising an aggregate, a binder, alumina fine powder, colloidal silica, and a boron-based antioxidant.   The amorphous refractory composition according to claim 3, wherein the colloidal silica has a silica solid content of 10% by mass to 50% by mass.   The amorphous refractory composition according to any one of claims 1 to 4, wherein the boron-based antioxidant is a particle having an average particle size of 0.1 to 100 µm.