Monolithic refractory

Abstract

To provide a monolithic refractory capable of securing usable life by suppressing quick setting and small in strength deterioration in a medium temperature region.SOLUTION: A monolithic refractory contains a basic aggregate, phosphoric acid as a binder, and polyacrylic acid and citric acid as additives, and may contain calcined alumina and / or basic aluminum lactate as additives, and the contents of phosphoric acid, polyacrylic acid, and citric acid relative to 100 pts.mass of the total content of the basic aggregate, calcined alumina, and basic aluminum lactate are 3.0 to 11.0 pts.mass, 0.1 to 1.0 pt.mass, and 0.5 to 2.0 pts.mass, respectively.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to a castable refractory material comprising a basic aggregate and phosphoric acid as a binder. [Background technology]

[0002] Various binders for monolithic refractories are known, including cement bonds such as alumina cement, chemical bonds such as phosphoric acid, phosphates, and silicates, resin bonds, pitch bonds, clay bonds, etc. Among these, monolithic refractories containing phosphoric acid or phosphates have a small decrease in strength in the medium to low temperature range. In particular, phosphoric acid has a greater effect than phosphates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 118677 / 1983 [Patent Document 2] Japanese Patent Application Publication No. 57-067070 Summary of the Invention [Problem to be solved by the invention]

[0004] However, castable refractories containing basic aggregates such as magnesia raw materials may be prone to rapid setting if they contain phosphoric acid as a binder (Patent Document 1). For this reason, monolithic refractories containing phosphoric acid as a binder are limited to those that mainly contain alumina raw materials as aggregates (Patent Document 2).

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and its purpose is to provide an unshaped refractory material that can suppress rapid setting, ensure a usable time, and has little reduction in strength in the medium to low temperature range. [Means for solving the problem]

[0006] One aspect of the present disclosure is The composition includes a basic aggregate, phosphoric acid as a binder, and polyacrylic acid and citric acid as additives. The additive may include calcined alumina and / or basic aluminum lactate, The present invention relates to a monolithic refractory material, characterized in that the contents of the phosphoric acid, the polyacrylic acid and the citric acid relative to 100 parts by mass of the total content of the basic aggregate, the calcined alumina and the basic aluminum lactate are 3.0 to 11.0 parts by mass, 0.1 to 1.0 parts by mass and 0.5 to 2.0 parts by mass, respectively.

[0007] As a result, even if the monolithic refractory containing basic aggregate such as magnesia raw material contains phosphoric acid as a binder, rapid setting is suppressed, the usable time can be secured, and the phosphoric acid exhibits the effect of reducing the decrease in strength in the medium and low temperature range. Although the reason for this is not entirely clear, it is thought that polyacrylic acid and citric acid have a pH buffering effect.

[0008] In one aspect of the present disclosure, The additive further comprises boric acid, The content of the boric acid is preferably 2.0 parts by mass or less (excluding 0 part by mass) relative to 100 parts by mass of the total content, which enables the pot life to be extended. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] A preferred embodiment of the present disclosure will be described in detail below. Note that the embodiment described below does not unduly limit the contents of the present disclosure described in the claims, and all of the configurations described in the embodiment are not necessarily essential as a means for solving the problems of the present disclosure.

[0010] The monolithic refractory of this embodiment contains a basic aggregate, phosphoric acid as a binder, polyacrylic acid and citric acid as additives, and may contain calcined alumina and / or basic aluminum lactate as additives, and the contents of phosphoric acid, polyacrylic acid and citric acid relative to 100 parts by mass of the total content of the basic aggregate, calcined alumina and basic aluminum lactate are 3.0 to 11.0 parts by mass, 0.1 to 1.0 parts by mass and 0.5 to 2.0 parts by mass, respectively. This prevents rapid setting of the monolithic refractory containing a basic aggregate such as magnesia raw material even if it contains phosphoric acid as a binder, ensures a pot life, and exhibits the effect of small strength reduction in the medium and low temperature range of phosphoric acid.

[0011] <Basic aggregate> The monolithic refractory of this embodiment includes a basic aggregate. The basic aggregate is not particularly limited as long as it is generally used in monolithic refractories, and examples thereof include magnesia raw material, spinel raw material, calcia raw material, and dolomite raw material. In this specification, typical magnesia raw material and spinel raw material are used as basic aggregate. The magnesia raw material is not particularly limited as long as it is generally used in monolithic refractories, and examples thereof include electrofused magnesia, seawater magnesia, natural magnesia, electrofused magnesia chrome, and sintered magnesia chrome. The spinel raw material is not particularly limited as long as it is generally used in monolithic refractories, and examples thereof include electrofused spinel and sintered spinel. The grain size of the basic aggregate can be appropriately adjusted depending on the application.

[0012] <Binder> The monolithic refractory material of this embodiment contains phosphoric acid as a binder. For example, a 75% by mass phosphoric acid solution may be used as the phosphoric acid, and the phosphoric acid concentration may be appropriately changed. The content of phosphoric acid relative to the total content of the basic aggregate, calcined alumina, and basic aluminum lactate of 100 parts by mass is preferably 3.0 to 11.0 parts by mass, more preferably 4.0 to 6.5 parts by mass. If it is less than 3.0 parts by mass, the strength decreases, and if it exceeds 11.0 parts by mass, the viscosity of the kneaded product increases, which is not preferable. In this specification, the content of phosphoric acid is calculated using the mass including components other than phosphoric acid (in the case of a 75% by mass phosphoric acid solution, the mass of the entire phosphoric acid solution including 25% by mass of components other than phosphoric acid) (the same applies to other raw materials).

[0013] <Polyacrylic acid> The monolithic refractory of this embodiment contains polyacrylic acid as an additive. The content of polyacrylic acid is preferably 0.1 to 1.0 part by mass, more preferably 0.25 to 0.5 part by mass, based on 100 parts by mass of the total content of the basic aggregate, the calcined alumina, and the basic aluminum lactate.

[0014] <Citric acid> The monolithic refractory material of this embodiment contains citric acid as an additive. The content of citric acid per 100 parts by mass of the total content of the basic aggregate, calcined alumina, and basic aluminum lactate is preferably 0.5 to 2.0 parts by mass, and more preferably 1.0 to 1.5 parts by mass. In this specification, there is no distinction between anhydrous citric acid and monohydrate.

[0015] By setting the polyacrylic acid and citric acid in the above ranges, rapid setting is suppressed even when the monolithic refractory containing basic aggregate contains phosphoric acid as a binder, and the pot life can be secured, and the effect of reducing the decrease in strength of phosphoric acid in the medium and low temperature range can be exhibited. Although the reason for this is not entirely clear, it is thought that polyacrylic acid and citric acid have a pH buffering effect.

[0016] <Boric acid> The monolithic refractory of this embodiment may further contain boric acid as an additive. The content of boric acid relative to 100 parts by mass of the total content of the basic aggregate, calcined alumina, and basic aluminum lactate is preferably 2.0 parts by mass or less (excluding 0 part by mass), more preferably 0.5 to 1.5 parts by mass. This promotes the effect of extending the pot life.

[0017] <Fine powder raw materials> The monolithic refractory of this embodiment may further contain a fine powder raw material as an additive. The fine powder raw material is not particularly limited as long as it is generally used for monolithic refractories, and examples thereof include silica fume, calcined alumina, magnesia fine powder, spinel fine powder, etc. Examples of the calcined alumina include alumina fine powder having an average particle diameter of 10 μm or less, and the content thereof is preferably 10.0 parts by mass or less, more preferably 3 to 8 parts by mass, relative to 100 parts by mass of the total content of the basic aggregate, the calcined alumina, and the basic aluminum lactate. This makes the viscosity of the kneaded material appropriate and has excellent fluidity, thereby improving the freedom of the shape of the monolithic refractory.

[0018] <Other additives> The monolithic refractory of this embodiment may further contain basic aluminum lactate as another additive. The content of basic aluminum lactate is preferably 0.2 to 5 parts by mass, more preferably 2 to 4 parts by mass, based on 100 parts by mass of the total content of basic aggregate, calcined alumina, and basic aluminum lactate. This makes it possible to suppress digestion (disintegration due to hydration) of the basic aggregate. The monolithic refractory of this embodiment may further contain a known dispersant, organic fiber, metal fiber, etc., depending on the purpose. EXAMPLES

[0019] Hereinafter, embodiments of the present disclosure will be described in detail.

[0020] <Sample preparation> The following raw materials were used in the examples of the present disclosure. That is, as the basic aggregate, fused magnesia containing 98% by mass of MgO as a magnesia raw material, and fused spinel containing 25% by mass of MgO and 75% by mass of Al2O3 as a spinel raw material were used. As the phosphate binder, a 75% by mass phosphoric acid solution was used, and as a comparative binder, a dialuminum phosphate solution was used. As the polyacrylic acid, a commercially available industrial chemical was used, and as the citric acid and boric acid, commercially available reagents were used. As the calcined alumina, alumina fine powder with an average particle size of 10 μm or less was used. As the basic aluminum lactate, 35% by mass of Al2O3 and 48% by mass of lactic acid were used.

[0021] The composition of the monolithic refractory raw materials is shown in Table 1. The content of each raw material was calculated using the mass of the entire raw material including impurities (for example, in the case of a 75% by mass phosphoric acid solution, the mass of the entire phosphoric acid solution including 25% by mass of components other than phosphoric acid). [Table 1]

[0022] The amount of water shown in Table 1 was added to the monolithic refractory raw material, and the mixture was kneaded to obtain a kneaded product. The obtained kneaded product was evaluated for fluidity and bending strength as follows.

[0023] <Liquidity> The flow test method of JIS R 2521 was applied, and the mixture filled in the flow cone was placed on a vibration table, the flow cone was removed, and the mixture was vibrated for 60 seconds with a vibration acceleration of 1.3G to measure the vibration flow value. The fluidity of the mixture was evaluated based on three items: (1) workability: whether the properties of the mixture are good and suitable for work, (2) pot life: whether the pot life required for pouring can be secured, and (3) fluidity. If all three items were excellent, they were rated as excellent (◎), if they were slightly inferior to excellent (◎) but good, they were rated as good (○), if they were slightly inferior to good (○) but usable, they were rated as acceptable (△), and if there was a problem with even one item and it was unusable, they were rated as unacceptable (×). If it was not possible to measure due to aggregation or hardening (rapid setting), they were rated as "N / A."

[0024] <Bending strength> The kneaded material was poured into a 40mm x 40mm x 160mm mold, cured at 50℃ for 24 hours, and heated at 200℃ for 24 hours to obtain monolithic refractories. The bending strength of the monolithic refractories was measured according to JIS R2553. Those that could not be poured into the mold due to aggregation or hardening (rapid setting) were marked as "N / A."

[0025] <Evaluation Results> The evaluation results are shown in Table 1.

[0026] The results of the examples were excellent in both fluidity and bending strength. The fluidity of examples 3 and 5 was evaluated as fair (△), but was not problematic enough for use. On the other hand, the comparative examples had problems in both fluidity and bending strength.

[0027] The content of phosphoric acid relative to 100 parts by mass of the total content of the basic aggregate, the calcined alumina, and the basic aluminum lactate was preferably 3.0 to 11.0 parts by mass, more preferably 4.0 to 6.5 parts by mass, which improved the bending strength and made the viscosity of the kneaded material appropriate, thereby enabling the production of a monolithic refractory material with excellent fluidity.

[0028] The content of polyacrylic acid relative to 100 parts by mass of the total content of basic aggregate, calcined alumina and basic aluminum lactate is preferably 0.1 to 1.0 parts by mass, more preferably 0.25 to 0.5 parts by mass. The content of citric acid relative to 100 parts by mass of the total content of basic aggregate, calcined alumina and basic aluminum lactate is preferably 0.5 to 2.0 parts by mass, more preferably 1.0 to 1.5 parts by mass. As a result, even if the monolithic refractory material containing basic aggregate contains phosphoric acid as a binder, quick setting is suppressed, the usable time can be secured, and the effect of phosphoric acid that the strength decrease in the medium and low temperature range is small can be exhibited. The reason is not necessarily clear, but it is considered that polyacrylic acid and citric acid have a pH buffering effect.

[0029] The content of boric acid relative to 100 parts by mass of the total content of the basic aggregate, the calcined alumina, and the basic aluminum lactate was preferably 2.0 parts by mass or less (excluding 0 parts by mass), more preferably 0.5 to 1.5 parts by mass. This promoted the effect of extending the pot life. The content of calcined alumina relative to 100 parts by mass of the total content of the basic aggregate, the calcined alumina, and the basic aluminum lactate was preferably 10.0 parts by mass or less, more preferably 3 to 8 parts by mass. This made it possible to obtain an amorphous refractory material with an appropriate viscosity and excellent fluidity. The content of basic aluminum lactate relative to 100 parts by mass of the total content of the basic aggregate, the calcined alumina, and the basic aluminum lactate was preferably 0.2 to 5 parts by mass, more preferably 2 to 4 parts by mass. This allowed the digestion of the basic aggregate (disintegration due to hydration) to be suppressed.

[0030] Although the present embodiment has been described in detail as above, it will be easily understood by those skilled in the art that many modifications are possible without substantially departing from the novel matters and effects of the present disclosure. Therefore, all such modifications are included in the scope of the present disclosure. For example, a term described at least once in the specification together with a different term having a broader meaning or the same meaning may be replaced with that different term anywhere in the specification. In addition, the configuration and operation of the manufacturing apparatus, etc. of the present embodiment are not limited to those described in the present embodiment, and various modifications are possible.

Claims

1. The composition includes a basic aggregate, phosphoric acid as a binder, and polyacrylic acid and citric acid as additives. The additive may include calcined alumina and / or basic aluminum lactate, The content of the phosphoric acid, the polyacrylic acid and the citric acid relative to a total content of the basic aggregate, the calcined alumina and the basic aluminum lactate is 2.25 to 8.25 parts by mass, 0.1 to 1.0 parts by mass and 0.5 to 2.0 parts by mass, respectively.

2. The monolithic refractory material according to claim 1, The additive further comprises boric acid, An amorphous refractory material characterized in that the content of boric acid per 100 parts by mass of the total content is 2.0 parts by mass or less (excluding 0 parts by mass).

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