JP2003201183A - Refractory for pouring - Google Patents

Abstract

(57) [Problem] To improve workability and durability of a material using an aluminum lactate compound as a binder or a cast material obtained by adding an organic short fiber to the material. SOLUTION: In terms of mass ratio, magnesia 0.1 ~
A refractory for casting, comprising a 100% refractory raw material composition containing 30%, an aluminum lactate compound, 0.01 to 2%, and a carboxyl group-containing polyether-based compound added as a dispersant. The aluminum lactate compound is one or more selected from aluminum glycolate lactate, aluminum lactate, aluminum citrate lactate, and basic aluminum lactate.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory for casting (hereinafter, referred to as refractory for lining used as a refractory for lining refractory such as a molten metal container and a molten metal processing apparatus).
It is called "casting material". ) Is related to.

2. Description of the Related Art As casting materials, various materials have been proposed in the past. For example, the alumina-magnesia material disclosed in Japanese Patent Application Laid-Open No. 6-137542 has particularly good durability. This alumina-magnesia material has the volume stability of alumina, the corrosion resistance of magnesia,
Furthermore, the slag resistance of the Al ₂ O ₃ .MgO spinel, which is generated by the reaction between alumina and magnesia during use, is combined with it to exhibit excellent durability. However, in recent iron making processes, various molten iron and molten steel treatments have been carried out for the purpose of improving the quality of steel products, and as a result, the conditions of use of refractories have become more severe, and there is a strong demand for refractory materials with even higher durability. There is. Alumina cement is generally used as a binder for the casting material. Alumina cement develops the curing strength of the casting material construction body by the hydration reaction with construction water. However, CaO in the component reacts with the refractory aggregate component to form a low melting point substance, which causes deterioration of corrosion resistance or peeling damage due to oversintering. Therefore, as a curing system excluding alumina cement, Japanese Patent Laid-Open No. 10-
In 194853, a casting material using basic aluminum lactate as a binder is proposed. This material is excellent in corrosion resistance and peeling damage resistance because it does not contain alumina cement, which causes generation of low melting point substances.

The casting material is added with a dispersant (sometimes referred to as a peptizer) for the purpose of ensuring workability. However, a casting material using an aluminum lactate compound as a binder has poor fluidity as compared with a combination of alumina cement and a dispersant, probably because of poor compatibility with the dispersant. As a result, the casting material impairs the workability and the densification of the structure of the construction body, and the effects of corrosion resistance and peeling damage resistance due to the removal of the alumina cement are not sufficiently exhibited. Further, organic short fibers are added to the casting material in order to accelerate the drying of the workability. The organic short fibers disappear or shrink when dried and form fine air passages in the tissue of the construction body, which serve as passages for water vapor generated from the construction moisture during drying, and accelerate the drying of the casting material construction body. If the material containing no organic short fibers is subjected to rapid heating and drying, it causes blistering or explosion of the construction body due to water vapor pressure. Various types of organic short fibers used here are known. Among them, unlike other types of fibers, polyvinyl alcohol short fibers dissolve in the construction water heated at the time of drying and thus disappear relatively early, and are particularly excellent in the effect of preventing blisters or explosions of the construction body. However, polyvinyl alcohol short fibers have a problem that the fluidity at the time of construction of a pouring material is lowered. Regardless of the type of organic short fibers, there is a tendency to reduce the fluidity of the casting material, but this tendency is particularly remarkable because of the high hydrophilicity of polyvinyl alcohol short fibers.
In the case of a casting material using an aluminum lactate compound as a binder, in addition to its poor fluidity, the addition of polyvinyl alcohol short fibers further lowers the fluidity. The casting material of the present invention, in a material using an aluminum lactate compound as a binder, or in a material obtained by adding organic short fibers to the binder, improves the above-mentioned problems, and aims to improve the workability and durability. And

The casting material of the present invention comprises:
In a mass ratio, a refractory raw material composition containing 0.1 to 30% magnesia is added to an aluminum lactate compound in an amount of 0.01 to 2%, and a carboxyl group-containing polyether compound is added as a dispersant. Characterize. In the present invention, the aluminum lactate compound functions as a binder that gels upon reaction with construction water and hardens the casting material. Unlike the brickwork, the construction material of the pouring material is easy to crack because it has no joints, but a microcrack is formed in the construction body structure due to curing shrinkage due to the gelation, and this microcrack absorbs thermal stress during drying. Preventing damage to the construction body by mitigating. The pouring material using alumina cement as a binder has the effect of imparting fluidity by adsorbing Ca ions eluted from the alumina cement by the dispersant and providing electrical repulsion between the particles of the refractory aggregate. On the other hand, in the casting material of the present invention using the aluminum lactate compound as a binder, since there is no Ca elution source, it is not possible to obtain the effect of imparting fluidity by adsorbing Ca ions of the dispersant. The present invention uses a carboxyl group-containing polyether compound as a dispersant. The carboxyl group-containing polyether compound is already known as a kind of dispersant for casting materials. Although it has the same adsorptivity to Ca ions as other dispersants, it also has the property of adsorbing Mg ions. The adsorption capacity for this Mg ion is a phenomenon that cannot be seen with other dispersants. And
The casting material of the present invention is an aluminum lactate compound in which a carboxyl group-containing polyether compound is adsorbed on Mg ions eluted from magnesia by using magnesia as a part of the aggregate, and a binder does not elute Ca ions. Even if it exists, it exhibits excellent fluidity. In addition to the above composition, the present invention further improves the corrosion resistance by adding calcium lactate. This is because CaO from calcium lactate reacts with Al ₂ O ₃ and SiO ₂ components of the aggregate component to generate a CaO-based low melting point substance, absorbs the thermal expansion of the construction body, and the refractory structure due to the thermal expansion. By preventing buckling damage. Calcium lactate not only produces CaO-based low melting point substances, but also lactic acid causes fine cracks in the structure of the construction body,
It has the function of absorbing thermal expansion due to microcracks. Other sources of CaO include alumina cement and slaked lime, but they do not have the effect of causing microcracks, and therefore cannot exert the remarkable effect of calcium lactate in thermal expansion absorption. Further, the present invention can secure sufficient fluidity even when polyvinyl alcohol short fibers are used as the organic short fibers. This is because, in addition to the carboxyl group-containing polyether compound fully exerting its function as a dispersant, the carboxyl group-containing polyether compound gels hydrophilic polyvinyl alcohol short fibers and aluminum lactate compound. This is probably because it acts to prevent integration with the organization.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. In addition, all% shown below are mass%. The refractory raw material composition of the present invention contains 0.1 to 30% magnesia. Others are, for example, alumina or alumina-silica,
The main material is silicon carbide, MgO.Al ₂ O ₃ based spinel (hereinafter referred to as “spinel”), etc., and if necessary, carbon, zircon, zirconia, spinel, etc. are combined.
These refractory raw materials may be either sintered products or electromelted products. The particle size of the refractory raw material is the same as conventional materials, such as coarse particles, medium particles,
Adjust appropriately to fine particles. Considering the fluidity at the time of construction and the filling property of the construction body, the refractory ultrafine powder with an average particle diameter of 10 μm or less is 1-2.
It is preferable to adjust the content to be 0% by weight. The refractory ultrafine powder is, for example, silica ultrafine powder, clay, alumina ultrafine powder, spinel ultrafine powder, or the like. A specific example of the ultrafine silica powder is preferably volatile silica. Specific examples of the ultrafine alumina powder and the ultrafine spinel powder are preferably calcined alumina and calcined spinel, respectively. If the proportion of magnesia in the refractory raw material composition is less than the range defined by the present invention, the Mg ion source decreases,
Poor in effect of imparting liquidity. If the amount is large, the spalling resistance is deteriorated. The proportion of magnesia in the refractory raw material composition is 0.
If it is less than 1%, it is not effective in imparting fluidity, and the effects of magnesia on corrosion resistance and slag penetration resistance cannot be exhibited. If it exceeds 30%, the spalling resistance is poor. If the particle size of magnesia is small, the specific surface area becomes large, and the elution of Mg ions is activated, and the effect of imparting fluidity is further improved. It is preferably adjusted to 25%.
It is more preferably adjusted to 0.5 to 15%. The magnesia particle size of 1 mm or less as used herein may be, for example, 0.075 mm or less, and finer light burned magnesia or the like as long as it is 1 mm or less. To specify the particle size, a JIS sieve opening is used, and for ultrafine particles, a laser type particle size distribution measuring device is used. Specific examples of the aluminum lactate compound include aluminum lactate glycolate, aluminum lactate, aluminum lactate citrate, and basic aluminum lactate. The chemical composition must contain 13% or more of Al ₂ O _{3 and} 10% or more of lactic acid. For example, aluminum lactate having Al ₂ O ₃ of 30 to 60% and lactic acid of 40 to 70% is preferable. Aluminum glycol lactate is, for example, 20 to 50% glycolic acid and 20 to 40 Al ₂ O ₃ .
% And lactic acid of 10 to 60% are preferable. The proportion of the aluminum lactate compound is preferably 0.01 to 2%, and more preferably 0.1 to 1.5%, as an external ratio to 100% of the refractory raw material composition. If the amount is too small, the effect of expansion and absorption is not obtained, and the spalling resistance is poor. If too many, curing shrinkage cracks become excessive and the corrosion resistance deteriorates. During production of the casting material, the aluminum lactate compound is added to the refractory raw material in the form of powder or dissolved in water beforehand. The aluminum lactate compound can be obtained from commercial products such as TAXELAM AS-800 and M-160P manufactured by Taki Chemical Co., Ltd. The carboxyl group-containing polyether compound as a dispersant has a structure containing a carboxyl group at the terminal or intermediate position of a polyether chain such as polyethylene glycol or polypropylene glycol. For example, product name Tight Lock or Mighty 2 manufactured by Kao Corporation
It is available from commercial products such as 1. It may be used in the form of powder or liquid. The liquid is, for example, one dispersed or dissolved in water or the like. The amount of the carboxyl group-containing polyether compound added is not particularly different from that of the dispersant in the conventional material, and is, for example, about 0.03 to 0.5%, more preferably 100% of the refractory raw material composition. 0.0
It is 5 to 0.3%. When used in liquid form, this ratio corresponds to the solid content conversion value. If the added amount is too small, the effect of imparting fluidity becomes insufficient, and if the added amount is too large, workability deteriorates due to retardation of curing. In addition to the above composition, the present invention further improves the corrosion resistance by adding calcium lactate. If the refractory structure is constrained in the circumferential direction like the lining of molten steel ladle, or if it is long like the lance or blast furnace gutter, the structure of the structure tends to buckle due to thermal expansion. Thermal expansion and contraction due to the addition of calcium lactate prevents the decrease in corrosion resistance caused by this. Calcium lactate is a compound of lactic acid and calcium, and its typical chemical formula is C ₆ H10O.
It is a ₆ Ca · _{0~5H 2} O. A common application is food additives such as calcium agents for nutritional enhancement. The production method is obtained, for example, by purifying crude calcium lactate obtained by adding calcium carbonate as a neutralizing agent during lactic acid fermentation. It can also be obtained by evaporating a solution obtained by neutralizing dilute lactic acid with calcium carbonate. The amount of calcium lactate added is 2% or less, which is an external weight of 100% of the refractory raw material composition. More preferably, it is 0.3 to 1.5%. If it is too large, the corrosion resistance will decrease. If the amount is small, the effect of adding calcium lactate will not be exhibited. Organic short fibers prevent blisters and explosions when the construction body is heated and dried. Specific examples thereof include natural fibers such as pulp, hemp and cotton, and synthetic fibers such as nylon, vinylon, polyvinyl alcohol, polypropylene, polyester, vinyl chloride, acrylic and aramid. Of these, use of polyvinyl alcohol short fibers is preferable. The polyvinyl alcohol short fibers disappear from a relatively low temperature range when the casting material is heated and dried, and a ventilation path for water vapor dissipation is formed at an early stage. The casting material of the present invention has excellent fluidity even when using polyvinyl alcohol short fibers. The size and amount of the organic short fibers are the same as those used in the conventional casting material. For example, the additive amount is 100% refractory raw material composition.
On the other hand, the outer coating is 0.5% or less, more preferably 0.01
~ 0.3%. If the amount is small, the effect of addition cannot be obtained, and if the amount is large, the corrosion resistance is lowered. In the present invention, other known additives for casting materials, such as coarse refractory particles, hardening modifier, short metal fibers (for example, stainless steel fiber), glass powder, carbon powder, pitch powder, ceramic fiber, foaming agent, etc. May be added. Further, a part of the refractory raw material composition may be aluminum hydroxide and / or magnesite in a range of, for example, 7% or less. The coarse refractory particles have an effect of preventing peeling damage by disrupting the development of cracks generated in the refractory structure. Specific examples thereof include alumina, spinel, mullite, magnesia and the like. Further, it may be a brick scrap mainly made of alumina or spinel, a refractory-used product, or the like. The particle size of the refractory coarse particles has a trade-off with the maximum particle size of the refractory aggregate, but
50 mm is preferable. Moreover, the ratio is 100 refractory aggregates.
It is preferably 35% or less, and more preferably 5 to 30%, as an external percentage. If it exceeds 35%, the strength of the construction body is deteriorated due to the poor balance of the grain size composition, and the corrosion resistance is deteriorated. Construction of the casting material of the present invention is carried out in the usual manner by adding 4 to 8% of construction water to the whole of the above-mentioned compounded composition and pouring it using a mold such as a core. In addition, the filling rate is improved by applying vibration during pouring.

EXAMPLES Examples of the present invention and comparative examples will be shown below. At the same time, the test results are shown. In each example, 6% of the work water was added to the pouring material composition shown in the table, and after kneading, the work was poured into the formwork. Further, after curing, it was dried at 110 ° C. for 24 hours to obtain a test piece. Flowability: at the point after the kneading (kneading for 3 minutes), J
The tap flow value (mm) was measured according to IS-R5201. The larger the value, the better the fluidity. Corrosion resistance; Steel piece by mass ratio: Converter slag (FeO content: 2
0%) = 50:50 as erosion agent, 1 for each test piece
A rotary erosion test was performed at 700 ° C. for 5 hours, and the erosion size was measured. Slag penetration resistance: After performing a rotary erosion test under the above conditions, the slag penetration size was measured. A dense construction body without buckling damage is more excellent in corrosion resistance and slag penetration resistance. Spalling resistance: It was performed using a rotary erosion tester. Mass ratio of steel piece: converter slag (FeO content; 20 mass%) = 50:50 as an erosion agent, heating at 1700 ° C. for 30 minutes, air cooling for 30 minutes, repeating this 6 times, and crack occurrence Was observed. ∘: No crack, ◯: Fine crack, Δ: Small crack, ×: Large crack. In this test, the degree of chipping damage resistance can be confirmed. Actual machine test: Pour into a 270 ton molten steel ladle using a core, cure, heat and dry at about 1000 ° C before use,
used. The rate of erosion (mm / charge) and the extent of structural spalling after use was confirmed.

[Table 1]

[Table 2] Each of the examples according to the present invention is excellent in fluidity, and is also excellent in corrosion resistance, slag penetration resistance, and spalling resistance of the construction body. This effect is confirmed in the durability of the actual machine test. In Examples 9 to 11, calcium lactate was further added, and the spalling resistance is particularly excellent. In addition, among the examples, the ones to which the polyvinyl alcohol short fibers are added have no discoloration in fluidity. Although not shown in the test results, the drying property is improved. On the other hand, Comparative Example 1 using alumina cement as a binder and a carboxyl group-containing polyether compound as a dispersant has excellent fluidity, but is inferior in corrosion resistance, slag penetration resistance and spalling resistance. In Comparative Examples 2 and 3, the binder is an aluminum lactate compound, but since a dispersant other than the carboxyl group-containing polyether compound is used, the fluidity is poor and the compactness of the construction product is insufficient, Inferior in corrosion resistance. In Comparative Example 4, the binder is an aluminum lactate compound and the dispersant is a carboxyl group-containing polyether compound, but the fluidity is insufficient because magnesia is not mixed, and the corrosion resistance and slag penetration resistance are also poor. . Comparative Example 5 containing a large amount of the aluminum lactate compound had excessive curing shrinkage cracks and was inferior in corrosion resistance and slag penetration resistance. Comparative Example 6 in which the ratio of the magnesia raw material is large, the spalling resistance, due to the occurrence of tissue destruction and cracks due to expansion,
Inferior in slag penetration resistance. Although the actual machine test was performed on the lining of the molten steel ladle, the casting material of the present invention is not limited to this, and is also used for the lining of molten steel containers such as tundish, vacuum degassing furnace, converter, electric furnace, and molten steel processing container. be able to.

The casting material of the present invention has the flowability, corrosion resistance, slag permeation resistance and spalling resistance required for casting materials as shown by the test results of the above examples. It is possible to exhibit excellent durability even under severe usage conditions in the molten metal container and the molten metal processing apparatus. As a result, it greatly contributes to the improvement of productivity in the iron-making industry, such as improving the operating rate of molten metal containers and molten metal processing equipment, reducing the unit consumption of refractory linings, and reducing the number of repairs for refractory linings.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshihiro Isobe             Kitakyushu City Hachiman Nishi Ward Higashihama 1-1 1-1 Kurosaki Ban             Second Manufacturing Division, Ma Co., Ltd. Yawata Irregular Factory             Within F-term (reference) 4G033 AA02 AA03 AA24 AB02 AB21                       AB27 BA01                 4K051 AA06 BE00 BE03 LC02

Claims (5)

[Claims] 1. The mass ratio of magnesia 0.1 to 0.1.
A refractory for casting construction, which is obtained by adding 0.01 to 2% of an aluminum lactate compound as an external agent and 100% of a carboxyl group-containing polyether compound as a dispersant to 100% of a refractory raw material composition containing 30%. 2. The refractory for casting according to claim 1, wherein the aluminum lactate compound is one or more selected from aluminum glycol lactate, aluminum lactate, aluminum citrate lactate, and basic aluminum lactate. 3. The refractory for pouring construction according to claim 1 or 2, wherein 100% of the refractory raw material composition is further added with calcium lactate of 2% or less. 4. A magnesia having a particle size of 1 mm or less is 0.1 to 2 out of magnesia in proportion to the entire refractory raw material composition.
The refractory for pouring construction according to claim 1, 2 or 3, which is 5%. 5. The refractory for casting according to claim 1, 2, 3 or 4, wherein 0.5% or less of polyvinyl alcohol short fibers are further added to 100% of the refractory raw material composition.