JPH0529631B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a refractory for pouring construction suitable as a lining material for blast furnace gutters, ladles, tundishes, and the like. [Prior Art] Pouring construction is widely used for lining various types of heavy furnaces due to its simplicity, such as lower equipment costs and no need for advanced construction techniques compared to stamp construction. As a refractory material for pouring construction (hereinafter referred to as pouring material), for example, in Japanese Patent Publication No. 59-33549, fireclay, peptizer, coagulant, and metal aluminum powder are added to refractory aggregate. This material has been proposed, and this material has become the mainstream in actual use. Further, Japanese Patent Publication No. 60-9983 proposes a material consisting of alumina cement, an acidic dispersant with a pH of 4 or less, an active dispersant, and a refractory fine powder for the refractory aggregate. [Conventional Problems] However, the material disclosed in Japanese Patent Publication No. 59-33549 usually has 3 to 12% by weight of fireclay added to give it fluidity during construction, but after lining,
After long-term use, the strength decreases significantly. When the present inventors investigated the cause, it was found that many fine cracks were generated inside the refractory structure due to shrinkage of the fireclay. In addition, fireclay has the drawbacks of relatively low refractoriness and the tendency to generate low-melting substances when reacting with slag. Conventional materials in which a large amount of fireclay is added are concerned about problems such as leakage of molten metal containers lined with these materials due to local melting damage depending on the conditions of use. On the other hand, the material disclosed in Japanese Patent Publication No. 60-9983 maintains the dispersion of refractory fine powder and alumina cement by adding an acidic dispersant with a pH of 4 or less, prolongs the pot life during construction, and allows for dense construction. You get a body. On the other hand, however, because it is dense, water evaporates smoothly during drying, and so-called dry explosions tend to occur. Although explosions can be prevented by lowering the drying temperature, the drying time becomes longer, which in turn reduces the operating rate of the furnace to be repaired. The object of the present invention is to provide a pouring material that solves the drawbacks of the conventional materials mentioned above. [Means for Solving the Problems] The present inventors sought a material that has high fluidity during construction without the addition of fireclay, the resulting constructed body is dense, and does not have the problem of dry explosion. I've done a lot of research. As a result, they discovered that good results can be obtained by adding metal aluminum powder and/or metal aluminum alloy powder in the presence of an acidic dispersant with a pH value of 5 or less, leading to the completion of the present invention. . i.e., in weight percentage, refractory aggregate
Particles with a particle size of 10 μm or less are 70% by weight
1 to 20 parts by weight of refractory fine powder, 0.01 to 4 parts by weight of metal aluminum powder and/or metal aluminum alloy powder, measured with 1% aqueous solution.
0.01 to 0.8% by weight of an acidic dispersant with a pH value of 5 or less,
A refractory for pouring construction consisting of 0.3 to 15% by weight of alumina cement. [Function] The refractory aggregate and additives used in the present invention are already known as refractory materials. However, the composition of the present invention as a pouring material is not only novel, but also provides effects that could not be expected from conventionally known techniques. The pouring material of the present invention exhibits good fluidity and suitable pot life during construction by using refractory fine powder in which particles with a particle size of 10 μm or less account for 70% by weight or more and an acidic dispersant with a pH of 5 or less. A dense construction body can be obtained. By not adding fireclay or by reducing its addition ratio, it is possible to prevent the occurrence of slight cracks and a decrease in corrosion resistance due to the addition of fireclay. Metallic aluminum powder reacts with construction moisture to generate reaction heat and _H2 gas at the same time. The heat of reaction promotes water evaporation and has the effect of hardening the construction body. The generation of _H2 gas forms degassing holes that serve as escape routes for water vapor,
Prevent dry explosion. Effects greater than those of metallic aluminum powder are known in materials to which fireclay is added. However, materials that do not contain fireclay or have a reduced amount of fireclay added do not exhibit sufficient fluidity during construction, and the _H2 gas generated by the reaction of the metal aluminum powder gets trapped inside, causing the construction body to swell. There is a phenomenon that occurs. In addition, there are fewer degassing holes formed. In contrast, in the present invention, by using an acidic dispersant with a pH of 5 or less, sufficient fluidity can be obtained without relying on fireclay. form. The specific materials that can be used as the refractory aggregate are the same as conventional pouring materials, and are not particularly limited. For example, coarse, medium, and fine particles include fused alumina, sintered alumina, calcined alumina, andalusite, bauxite, sillimanite, mullite, siyamoto, waxite, silica, zircon, chromite, magnesia alumina, and spinel. , magnesia, silicon carbide, silicon nitrogen, graphite, amorphous carbon, and the like can be used. The maximum particle size in this case is, for example, 3 to 30 mm. The refractory fine powder in which particles with a particle size of 10 μm or less account for 70% by weight or more is one or two types selected from, for example, alumina, hydrated amorphous silica, anhydrous amorphous silica, zircon, silicon carbide, chromium oxide, titanium oxide, activated carbon, etc. It is. During construction, this fine refractory powder is dispersed with a dispersant and then aggregated by the action of Ca ⁺⁺ and Al ⁺⁺⁺ ions eluted from alumina cement, creating a dense and high-strength structure in the constructed structure. . If the amount of refractory fine powder added is less than 1% by weight of the above-mentioned refractory aggregate with respect to 100% by weight, the addition has no effect, and if it exceeds 20% by weight, the compactness becomes excessive and the fire-resistant boring property is reduced. . A more preferable range is 3 to 15% by weight. Metal aluminum powder generates reaction heat and H ₂ gas when it reacts with construction moisture, and has the effect of evaporating moisture due to the reaction heat and forming degassing pores due to the H ₂ gas. In the present invention, not only metal aluminum powder but also
A similar effect can be obtained with metal aluminum alloy powder. As the metal aluminum alloy powder, Al-
Mg, Al−Si−, Al−Mn, Al−Cn, Al−Mg−
Although effects were confirmed for all materials including Si, Al--Mg and Al--Si are preferred from an economical point of view as they are relatively inexpensive. If the external ratio of metallic aluminum powder and/or metallic aluminum alloy powder to 100% by weight of the refractory aggregate is less than 0.01% by weight, the addition will have no effect, and if it exceeds 4% by weight, a large amount of metal powder, which is a low melting point substance, will be added. Since it is added, corrosion resistance decreases. More preferably, it is 0.05 to 1% by weight. In order to obtain sufficient reactivity, the particle size is determined by e.g.
Use one with a diameter of 0.3 mm or less. Various types of dispersants are known for use in pouring materials, but in the present invention, acidic dispersants having a pH value of 5 or less are particularly used. If the PH value exceeds 5, the fluidity during construction is reduced, and H ₂ gas generated from the metal aluminum powder and/or the metal aluminum alloy powder is trapped in the construction body, causing a swelling phenomenon. Note that the PH value here refers to a value measured using a 1% aqueous solution. Examples of dispersants with a pH value of 5 or less include polyacrylic acid (PH2), acidic polyphosphate (PH4 to
5), one or more selected from ultra polyphosphates (PH 1 to 2). refractory aggregate
If the outer coating ratio is less than 0.01% by weight with respect to 100% by weight, there will be no effect of imparting fluidity, and if it exceeds 0.8% by weight, the curing time will be too long and the workability will deteriorate. More preferably, it is 0.03 to 0.3% by weight. As the alumina cement, it is preferable to use a product equivalent to Class 1 or Class 2 of the JIS standard, or a super class product with a small amount of CaO. Refractory aggregate 100
If the outer weight is less than 0.3% by weight, it has no effect as a binder. If it exceeds 15% by weight, curing will be too rapid and the pot life will not be sufficient, and low melting point substances will be produced in large quantities, reducing hot strength and slag resistance. Preferably it is 1 to 10% by weight. In addition to the above-mentioned formulations, the present invention also uses additives known as additives for conventional pouring materials, such as Si, Fe, and Fe.
A reaction inhibitor such as ammonium borate for metal powder such as -Si, fibers such as ceramic fiber, organic fiber, and metal fiber, and metal aluminum powder may be added as appropriate. [Examples] Tables 1 and 2 show examples of the present invention and comparative examples thereof. The test methods for the various tests shown in the table are as follows. The curing time was unified to 24 hours for each row. Pot life: This is the time during which fluidity is maintained; if it is short, the filling properties during construction will decrease. If it is too long, curing will not be completed forever and construction efficiency will be poor. Preferred is generally 20 to 120 minutes. Curing time: The time required for complete curing after kneading with water. Once this curing is completed, subsequent demolding, heat drying, etc. can be performed. Swelling test: A test piece poured into a cylindrical shape of φ50 x 150 mm was cured, and during the curing, 0.5
A swelling of more than mm was marked with an x, and a swelling of less than 0.5 mm was marked with an ○. Dry explosion test: □After being poured into a cube shape of 60 x 60 mm and cured, it was placed in an electric furnace at a temperature of 500℃. At that time, those whose tissues were destroyed by water vapor pressure were marked with an "x", and those whose tissues were not destroyed were marked with an "○". Powdering rate after firing: □Pour into a 40 x 40 mm cube shape, heat dry at 110℃ x 24 hours after curing, put the obtained test piece in a pod, fill the gap with coke breeze, In this state, it is fired in an electric furnace at 1100°C for 2 hours. Next, after performing this cycle of firing and cooling after firing once, 10 times, and 20 times, the test piece was placed in a washer, and a 5.4 kg weight was dropped from a height of 210 mm. This was repeated 10 times, and the amount powdered to 2 mm or less was expressed as a percentage of the weight of the entire test piece before powdering. This pulverization rate after firing was determined as a method for evaluating strength deterioration during long-term use of poured materials. The smaller the value, the lower the powdering rate, and therefore the less strength deterioration occurs even after long-term use. Spalling resistance: A test piece was prepared by casting into a shape of 120 x 60 x 50 mm, curing, and then heating and drying at 110°C for 24 hours. One side is inserted into an electric furnace at 1200℃, heated for 30 minutes, then taken out and cooled in the air, and when it has cooled to 300℃, it is inserted into the electric furnace again for 30 minutes, and the process is repeated 10 times. The situation was observed. ○...Almost no sharpness. △...A sharpness is observed, but not much. ×...I get angry a lot. Corrosion resistance: The erosion index was determined by a rotating drum type erosion test. The cross section perpendicular to the length direction is 65mm on the top side x bottom side
After curing, a trapezoid of 130 mm x 50 mm height is cast into a trapezoid column shape with a length of 120 mm.
It was heated and dried at 110°C for 24 hours to obtain a test piece. The test pieces were laminated in a drum and heated at 1570°C for 1 hour using an oxygen-propane heat source six times. For each example shown in Table 1, blast furnace slag was used as the erosion agent. On the other hand, the second
Steel was used as the eroding agent in each of the examples shown in the table. The index is the value when the erosion dimension of Comparative Example 1 and Comparative Example 9 in Tables 1 and 2 is set as 100, respectively, and the smaller the value, the better the corrosion resistance. Compressive strength: A test piece was prepared by pouring it into a 40 x 40 x 160 mm shape, curing it, and then heating and drying it at 110°C for 24 hours.

【table】

[Table] This is the percentage of external costs.

【table】

[Table] This is the ratio of external charges to %.
*(2) Corrosion resistance of Examples 9 to 12 was not measured.
Comparative Example 1 and Comparative Example 9 are the most commonly used materials to which fireclay is added.
Due to the large proportion of fireclay that imparts fluidity, fine cracks occur due to drying shrinkage, and because it is a low melting point material, it has poor powdering rate, corrosion resistance, and compressive strength after firing. In Comparative Example 2 and Comparative Example 10, the pot life was insufficient due to the use of a dispersant having a pH of over 5, and furthermore, swelling was observed. Comparative Example 8 and Comparative Example 11 had good fluidity and good pot life without adding fireclay by using an acidic dispersant with a pH of 5 or less, but when metal aluminum powder or metal aluminum alloy powder was added. Therefore, no deaeration holes were formed and dry explosion occurred. Other comparative examples outside the scope of the present invention were also unsuitable as pouring materials, as shown in the test results shown in the table. On the other hand, all of the examples of the present invention obtained good results, and although not shown in the table, they could be used without problems even in tests in which they were actually lined in a furnace. [Effects] According to the present invention, since it is not necessarily necessary to add fireclay, which is indispensable in conventional pouring materials, it is possible to avoid the problems of fireclay, such as the occurrence of slight cracks and a decrease in corrosion resistance. Although materials using refractory fine powder have excellent densities, they have shortcomings such as a short pot life and a tendency to explode when heated and dried. By adding a dispersant in combination, as shown in the results of the Examples, it was possible to obtain an extremely useful effect as a pourable material, with a suitable pot life and no swelling or explosion.

Claims (1)

[Claims] 1 In terms of weight percentage, based on 100% by weight of fire-resistant aggregate,
1 to 20% by weight of refractory fine powder, in which particles with a particle size of 10 μm or less account for 70% or more, metal aluminum powder and/or metal aluminum alloy powder, 0.01 to 20% by weight
A refractory for pouring construction consisting of 0.01-0.8% by weight of an acidic dispersant and 0.3-15% by weight of an alumina cement having a PH value of 5 or less as measured in a 1% aqueous solution.