JP6599574B1 - Curing accelerator, cement composition, and amorphous refractory - Google Patents

Abstract

A novel curing accelerator, cement composition, and amorphous refractory are provided. A cement hardening accelerator includes strontium hydroxide and / or a hydrate thereof. The strontium hydroxide and / or hydrate thereof may be strontium hydroxide octahydrate. The cement may be an alumina cement. [Selection figure] None

Description

  The present invention relates to a curing accelerator, a cement composition, and an amorphous refractory.

  Unshaped refractories including refractory aggregate and cement as binder are used in the form of casting material, iron coating material, spraying material, etc. It functions as a thing. In order to retain the shape as a refractory structure, it is necessary that the cement and moisture be cured by a hydration reaction.

  This curing reaction depends on the temperature. Generally, the curing reaction occurs early when the temperature is high, and the curing reaction is delayed when the temperature is low. For this reason, in actual use situations, when an irregular refractory is used in winter, problems such as a long curing time and a long construction period are likely to occur.

  In order to prevent this curing delay, sodium aluminate is used as a curing accelerator. However, due to the fact that sodium aluminate was designated as a deleterious substance by the revision of the Industrial Safety and Health Law, the manufacturer was restricted from using sodium aluminate, and the use side was not allowed to use deleterious substances mixed with sodium aluminate. Not recommended (for example, Non-Patent Document 1).

Sodium aluminate safety data sheet (SDS) [Internet <URL: http://www.st.rim.or.jp/~shw/MSDS/19233250.pdf>]

  An object of this invention is to provide a novel hardening accelerator, a cement composition, and an amorphous refractory.

  As a result of intensive studies in view of the above problems, the present inventors have found that strontium hydroxide and / or its hydrate (hereinafter referred to as “strontium hydroxide-based active ingredient”), which is a non- deleterious substance, is aluminate. The inventors found that cement hardening can be promoted in the same manner as soda, and further studies were made based on this finding, thereby completing the present invention.

That is, the present invention includes the following aspects.
Item 1. A cement hardening accelerator comprising strontium hydroxide and / or a hydrate thereof.
Item 2. Item 2. The curing accelerator according to Item 1, wherein the strontium hydroxide and / or hydrate thereof is strontium hydroxide octahydrate.
Item 3. Item 3. The curing accelerator according to Item 1 or 2, wherein the cement is alumina cement.
Item 4. A cement composition comprising cement and the curing accelerator according to Item 1 or 2.
Item 5. An amorphous refractory comprising a fireproof aggregate, cement, and the curing accelerator according to Item 1 or 2.
Item 6. Item 6. The amorphous refractory according to Item 5, wherein the content of the curing accelerator is 0.001 to 1 part by mass with respect to 100 parts by mass of the refractory aggregate.

  The curing accelerator of the present invention can promote the curing of cement. Moreover, since the hardening accelerator of this invention contains the strontium hydroxide type | system | group active ingredient which is a non- deleterious substance, it is excellent in safety.

  Hereinafter, the hardening accelerator, cement composition, and amorphous refractory of the present invention will be described in detail.

<Curing accelerator>
A hardening accelerator is for accelerating hardening of cement. Moreover, since the hardening rate of a cement changes according to temperature etc., a hardening accelerator is used in order to adjust the hardening rate of a cement. From such a point, the curing accelerator can also be referred to as a curing regulator.
The cement is not particularly limited, and examples thereof include Portland cement (eg, ordinary Portland cement, early-strength Portland cement), mixed cement (eg, blast furnace cement, fly ash cement, silica cement), alumina cement, and combinations thereof. It is done. Of these, alumina cement is preferred.
Alumina cement refers to cement containing alumina (Al ₂ O ₃ ).
Alumina cement usually contains aluminate lime salt (a two-component compound of CaO and Al ₂ O ₃ ). The calcium aluminate, for _{example, 3CaO · Al 2 O 3,} 2CaO · Al 2 O 3, CaO · Al 2 O 3, CaO · 2Al 2 O 3, CaO · 6Al 2 O 3, 12CaO · 7Al 2 O 3 And combinations thereof.
The curing accelerator contains a strontium hydroxide-based active ingredient. The strontium hydroxide active ingredient is preferably strontium hydroxide hydrate, more preferably strontium hydroxide octahydrate.
The content of the strontium hydroxide-based active ingredient is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, and further preferably 95% by mass or more, based on the total mass of the curing accelerator. And even more preferably 99% by mass or more.
The curing accelerator may further contain other components. Other components include inorganic components [eg, chloride (eg, NaCl, CaCl ₂ , KCl), nitrite (eg: Ca (NO ₂ ) ₂ , NaNO ₂ , KNO ₂ ), nitrate (eg, Ca ( NO ₃ ) ₂ , NaNO ₃ , KNO ₃ ), sulfate (eg CaSO ₄ , Na ₂ SO ₄ , K ₂ SO ₄ ), thiocyanate (eg NaSCN), carbonate (eg Li ₂ CO ₃ , Na ₂ CO ₃ , K ₂ CO ₃ ), sodium silicate, aluminas (eg, Al (OH) ₃ , Al ₂ O ₃ )], organic components [eg, amines, organic acid Ca salts, maleic anhydride] Can be mentioned. These can be used alone or in combination of two or more. In addition, in these, the component (Example: Sodium silicate) which has a function as a dispersing agent is also contained, The said component can also be used as a dispersing agent.
It is preferable that a hardening accelerator does not contain the component (For example: sodium aluminate) designated as a poisonous substance or a deleterious substance from a safety point.

<Cement composition>
The cement composition, in one embodiment, includes cement and a set accelerator.
The blending amount of the curing accelerator is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, more preferably 0.1 parts by mass or more with respect to 100 parts by mass of the cement from the viewpoint of promoting the curing reaction at a low temperature or the like. 5 parts by mass or more is particularly preferable. In addition, the blending amount of the curing accelerator is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less with respect to 100 parts by mass of cement from the viewpoint of handleability and workability.
In another embodiment, the cement composition includes cement and a strontium hydroxide-based active ingredient. The compounding amount of the strontium hydroxide-based active ingredient can be the same as the compounding amount of the curing accelerator in the above embodiment.
As the cement and the strontium hydroxide-based active ingredient, the same ingredients as those exemplified in the section of “curing accelerator” can be used, and preferred ingredients are also the same.

  The cement composition may further contain an additive. Examples of the additive include a refractory powder, a dispersant, an explosion prevention agent, a thickener, and a combination thereof.

  Although it does not restrict | limit especially as a refractory powder, For example, an alumina raw material (Example: High alumina raw materials, such as a fused alumina, sintered alumina, calcined alumina), an alumina-silica raw material (Example: calcined bauxite, mullite, sillimanite) , Kayanite, andalusite), silica-alumina raw materials (eg, rholite, chamotte, clay), siliceous raw materials (eg, silica, silica sand, silica, fused quartz), spinel raw materials (eg, chromite, sintered spinel) , Electrofused spinel, magcro), basic materials (eg, magnesia clinker, forsterite, dolomite clinker, calcia), carbide materials (eg, zircon material, zirconia material, silicon carbide, zirconium carbide, aluminum carbide, carbonized) Boron), nitride materials (eg silicon nitride, zirconium nitride, boron nitride, aluminum nitride) Ion), a carbonaceous material (e.g. coke, natural graphite, artificial graphite, anthracite, carbon black, carbon brick scraps, electrode chips), sodium silicate mass, silicon, chromium oxide and the like. These can be used alone or in combination of two or more.

Examples of the dispersant include metaphosphate (eg, NaPO ₃ ), polymetaphosphate (eg, sodium trimetaphosphate, sodium hexametaphosphate), pyrophosphate (eg: sodium pyrophosphate), carboxylate (eg, citrate). Acid soda, sodium tartrate), polycarboxylate-based polymers (eg, sodium polyacrylate), organic sulfonates (eg, sodium naphthalene sulfonate), and combinations thereof. In addition, in these, the component (Example: metaphosphate, polymetaphosphate) which has a function as a hardening accelerator is also contained, and the said component can also be used as a hardening accelerator.

  Examples of explosion prevention agents include foaming agents (eg, metallic aluminum, metallic magnesium), organic fibers (eg, vinylon fibers, polypropylene fibers, vinyl chloride fibers), basic colloids (eg, aluminum lactate), and nitrogen gas generation and decomposition. Examples thereof include fibers and humic acids. These can be used alone or in combination of two or more.

  Examples of the thickener include methyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, and polyacrylamide. These can be used alone or in combination of two or more.

  The blending amount of the additive can be appropriately selected according to the type, use, etc., for example, can be selected from the range of 0.5 to 5000 parts by mass with respect to 100 parts by mass of cement. It may be a smaller amount (e.g., 1 to 80 parts by mass) than the blending amount, or may be the same or more (e.g., 100 to 3000 parts by mass) as the blending amount of cement.

<Unshaped refractories>
The amorphous refractory includes, in one embodiment, refractory aggregate, cement, and a hardening accelerator.
The blending amount of the cement is preferably 0.1 parts by mass or more and more preferably 1 part by mass or more with respect to 100 parts by mass of the refractory aggregate from the viewpoint of bonding with the refractory aggregate. The cement content is preferably 15 parts by mass or less and more preferably 10 parts by mass or less with respect to 100 parts by mass of the refractory aggregate in terms of hardness.
The blending amount of the curing accelerator is 0.001 mass with respect to 100 mass parts of the refractory aggregate (or 100 mass parts of the refractory aggregate and cement in total) from the viewpoint of promoting the curing reaction at a low temperature or the like. Part or more, preferably 0.005 part by weight or more, more preferably 0.01 part by weight or more. Further, the blending amount of the hardening accelerator is preferably 1 part by mass or less with respect to 100 parts by mass of the refractory aggregate (or 100 parts by mass in total of the refractory aggregate and the cement) from the viewpoint of handleability and workability. 0.8 parts by mass or less is more preferable, and 0.5 parts by mass or less is more preferable. In addition, the compounding quantity of the hardening accelerator with respect to 100 mass parts of cement may be the same as the compounding quantity illustrated by the term of the "cement composition".
The amorphous refractory includes, in another embodiment, refractory aggregate, cement, and a strontium hydroxide-based active ingredient.
The blending amount of cement can be the same blending amount as in the above embodiment. Moreover, the compounding quantity of a strontium hydroxide type | system | group active ingredient may be the same as the compounding quantity of the hardening accelerator in the said embodiment.

As the refractory aggregate, the same components as those exemplified as the refractory powder in the section “Cement composition” can be used. The refractory aggregate is preferably at least one selected from alumina raw materials, alumina-silica raw materials, silica-alumina raw materials, and siliceous raw materials, and more preferably at least one selected from alumina, calcined bauxite, and silica. .
The particle size (or particle size) of the refractory aggregate is not particularly limited, but is, for example, 5.0 mm or less, preferably 4.5 mm or less, and more preferably 4.0 mm or less. The particle size (or particle size) of the refractory aggregate is based on, for example, the size of mesh openings used for sieving.
The refractory aggregate may include coarse powder having a particle size of more than 100 μm, fine powder having a particle size of 100 μm or less (including ultrafine powder having a particle size of 50 μm or less), and combinations thereof.
When combining coarse powder and fine powder as a fireproof aggregate, the mass ratio of coarse powder to fine powder is, for example, 60:40 to 99: 1, preferably 70:30 to 95: 5, and more preferably 80:20 to 90:10.
As the cement and the strontium hydroxide-based active ingredient, the same ingredients as those exemplified in the section of “curing accelerator” can be used, and preferred ingredients are also the same.

The amorphous refractory may further contain an additive. Examples of the additive include a dispersant, an explosion preventing agent, a thickener, and a combination thereof.
As the dispersant, the same components as those exemplified in the section “Cement composition” can be used. The blending amount of the dispersant is not particularly limited, but is, for example, 0.001 to 1 part by mass with respect to 100 parts by mass of the refractory aggregate (or a total of 100 parts by mass of the refractory aggregate and cement), 0.01 to 0.5 parts by mass.
As the explosion preventing agent, the same components as those exemplified in the section “Cement composition” can be used. The blending amount of the explosion preventing agent is not particularly limited, but is, for example, 0.001 to 1 part by mass with respect to 100 parts by mass of the refractory aggregate (or 100 parts by mass of the refractory aggregate and cement), Preferably it is 0.01-0.5 mass part.
As the thickener, the same components as those exemplified in the section “Cement composition” can be used. The blending amount of the thickener is not particularly limited, but is, for example, 0.001 to 1 part by mass with respect to 100 parts by mass of the refractory aggregate (or 100 parts by mass of the refractory aggregate and cement), Preferably it is 0.01-0.5 mass part.

The amorphous refractory usually has the property of being cured by water (hydraulic). When adding and hardening water to an amorphous refractory, the addition amount of water is 1-15 mass parts with respect to 100 mass parts of amorphous refractories, Preferably it is 5-10 mass parts.
In addition, it is preferable that the amorphous refractory does not contain water (free water), but water (free water) is added together with a hydration terminator (eg, chelating agent, condensed phosphate, aluminum phosphate, boric acid). It can also be contained.
The curing temperature is not particularly limited, but can be selected from a range of 5 to 40 ° C., for example. In the present invention, even if the curing temperature is low (eg, 5 to 15 ° C.), it can be cured in a short time (eg, 1 to 3 hours).

  The amorphous refractory is used in the form of, for example, a casting material, a trowel coating material, or a spraying material. Moreover, the hardened | cured material of an amorphous refractory can be used as linings, such as a melting furnace, a holding furnace, a ladle, and a bowl, which function with various heat sources.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited to these.

（表１の原料の水酸化ストロンチウムは、水酸化ストロンチウム８水和物である。また、従来例、実施例、及び比較例１〜３の組成は質量部を基準とする。） Each raw material other than the added water was mixed in a 10 L capacity V-shaped mixer in the ratio shown in Table 1 to prepare an amorphous refractory.

(The raw material strontium hydroxide in Table 1 is strontium hydroxide octahydrate. The compositions of the conventional examples, examples, and comparative examples 1 to 3 are based on parts by mass.)

The amorphous refractory and the added water were allowed to stand separately in a thermostat at 10 ° C. for 24 hours. Added water was added to the amorphous refractory after standing, and the mixture was kneaded with a 10 L capacity wing mixer for experiments.
After kneading, the flow value was measured, and after the measurement, the kneaded product was put in a plastic bag, and kept in a 10 ° C. incubator, and the flow value was measured every 1 hour until cured. The flow value was measured according to JIS-R2521.

（表２のフロー値は大きいほど流動性の高いことを示す（１００〜３００の範囲）。フロー値が１２０以下の場合、流動性が低く施工には適さない。） The experimental results are shown in Table 2.

(The larger the flow value in Table 2, the higher the fluidity (in the range of 100 to 300). When the flow value is 120 or less, the fluidity is low and not suitable for construction.)

In the conventional example and the example, the change in the flow value immediately after the kneading is almost the same, and is cured in the same time.
Since Comparative Example 1 did not add a curing accelerator, it was not cured even after 10 hours. In Comparative Example 2, magnesium hydroxide which is common to strontium hydroxide in terms of metal hydroxide is added, but it is not cured after 10 hours as in Comparative Example 1. In the comparative example 3, although calcium hydroxide is added, it turns out that fluidity | liquidity (workability | operativity) is inhibited.

  As is apparent from the above, strontium hydroxide exhibits the same curing behavior as sodium aluminate, unlike other metal hydroxides. Strontium hydroxide, which is a non- deleterious substance, can be used as a substitute for sodium aluminate, which is designated as a deleterious substance, and can cure an amorphous refractory with an appropriate working time even at low temperatures such as in winter.

Claims (6)

A cement hardening accelerator comprising strontium hydroxide octahydrate . The hardening accelerator according to claim 1, wherein the cement is an alumina cement. And a curing accelerator as claimed in claim 1 with the cement, the cement composition. A refractory aggregate and cement in claim 1 and a curing accelerator described, monolithic refractories. The amorphous refractory according to claim 4, which is used for melting furnace, holding furnace, ladle, or firewood lining. The amorphous refractory according to claim 4 or 5, wherein the content of the curing accelerator is 0.001 to 1 part by mass with respect to 100 parts by mass of the refractory aggregate.