JP4855339B2 - Amorphous refractories and methods for producing refractories - Google Patents

Description

  The present invention is an amorphous refractory capable of increasing the heat spalling resistance and peeling resistance of a refractory such as an irregular refractory and a refractory brick and extending the life of the refractory, and manufactured from the irregular refractory. The present invention relates to a method for producing a high strength refractory.

Conventionally, for firewood, refining furnace or secondary refining furnace, ladle, continuous casting tundish, etc. Refractories such as bricks are lined.
These refractories are subject to thermal changes due to heating and cooling during use, causing thermal spalling, etc., causing local or entire wear and tearing or cracking due to mechanical shock when removing deposits To do. As a result, the life of the smelting furnace and the refractory for casting is shortened, the productivity is lowered, and the cost for repairing the refractory is also increased.

Therefore, we are working to extend the life of refractories and furnaces by repairing the worn parts by spraying, glazing, etc., selecting refractory materials, and improving repair methods.
However, the use conditions of smelting furnaces and the like are becoming more severe and the quality of refractories is further improved, and there is a demand for refractories with sufficient characteristics against spalling and melting. As a countermeasure, a method of reinforcing the strength by adding a large amount of metal fiber has been proposed.

For example, Patent Document 1 includes a long metal fiber having a maximum cross-sectional diameter of 0.2 to 1.5 mm and a length of 20 to 50 mm, and a maximum cross-sectional diameter of 0.2 to 1.5 mm and a length of 1 to 20 mm. Combining short metal fibers with a total amount of 35% by mass or less (expressed in the literature is% by weight) and adding them to the amorphous refractory, the toughness of the refractory while maintaining high workability It has been proposed to improve cracking and prevent cracking and growth due to thermal and structural spalling.
Patent Document 2 discloses that the surface of a metal fiber having a diameter of 0.1 to 0.6 mm and a length of 20 to 80 mm is coated with an organic substance of 0.1 to 10 μm, and 5 to 20% by mass (expression in the document). Has been proposed as a means for improving the flowability of the cast refractory material to be added at a ratio of% by weight.
Further, Patent Document 3 also proposes a means for achieving high thermal conductivity by adding a large amount of metal.

JP-A-8-268767 JP 2006-89321 A JP 2004-315348 A

  However, in the said patent document 1, although the improvement of kneading | mixing property and fluidity | liquidity is proposed by using metal fiber from which length differs in metal fiber, since the maximum diameter is using the refractory particle of 1-10 mm, When a large amount of metal fiber is added, the metal fibers overlap in the casting work and the distribution of the metal fiber becomes high. There was a problem that particles were not filled and remained as voids.

  In Patent Document 2, to improve the fluidity, a coated metal fiber having an organic coating of 0.1 to 10 μm is added to a linear metal fiber having a substantially circular cross section and a smooth surface. However, the particle size of the refractory material to be applied is not described, and the portion where the distribution of the metal fiber is high is not filled with coarse particles, and the refractory material depends on the distribution state of the metal fiber. Grain segregation occurs and there is great variation as a construction body, and the original function cannot be exhibited. The same applies to Patent Document 3.

  In the present invention, for such problems, an unshaped refractory that can achieve the high-strength reinforcing effect of the metal fiber and the uniformity of the construction body by suppressing the generation of voids during construction work, and It aims at providing the manufacturing method of the refractory formed using this amorphous refractory.

The present invention proposes the following (1) to (7) as means for suppressing the generation of voids or unfilled sites in the construction work and obtaining the uniformity of the construction body.
(1) From 20 parts by mass to 60 parts by mass of a dendritic metal aggregate, and 40 parts by mass to 80 parts by mass and a refractory aggregate having a maximum particle size of 0.85 mm or less Furthermore, 10 mass parts or less of moisture is added to the aggregate of the fire-resistant aggregate, and the dendritic metal aggregate is composed of a plurality of wires in the form of wires. The tip is branched into a plurality of shapes such as capillaries manufactured by shearing, and the cross-sectional area of one branch is 0.05 mm ² or more and 1 mm ² or less. Standard refractory.
(2) The refractory aggregate is alumina, magnesia, siliceous, silica-alumina, alumina-magnesia, alumina-spinel, alumina-spinel-magnesia, clay, chrome, waxy, zircon One or two of zirconia, carbon, silicon carbide, magnesia, magnesia-carbon, alumina-carbon, alumina-silicon carbide-carbon, alumina-magnesia-carbon, or zirconia-carbon The amorphous refractory according to (1), which is as described above.

( 3 ) A method for producing a refractory, characterized in that the metal aggregate, the refractory aggregate, and water described in (1) or (2) are kneaded, poured into a mold, and cured and dried.
( 4 ) The desired amount of the metal aggregate filling the construction space, the refractory aggregate and water are kneaded, then poured into a formwork and cured and dried. ( 3 ) Manufacturing method.
( 5 ) After putting the metal aggregate as described in (1) or (2) into the mold in advance and filling the construction space with the metal aggregate, the fireproof aggregate as described in (1) or (2) And a slurry in which water is kneaded is poured into the mold and dried by curing.

  According to the present invention, the strength of the refractory can be greatly improved, and the spalling resistance can be improved. Further, the functional life of the casting nozzle, the furnace life of the refining furnace, the secondary refining furnace, and the like can be extended, and the productivity can be improved, the refractory cost can be reduced, and cracking troubles can be reduced.

  When the present inventors reinforce strength by containing a large amount of metal aggregate in the refractory aggregate, the particle size segregation of the refractory aggregate is present in the portion where the distribution of the metal aggregate is high. In response to the problem of large variations in the construction body, the size of the refractory aggregate is considered to be due to particle size segregation of the refractory aggregate. ,Study was carried out. As a result, if the maximum diameter of the refractory aggregate is smaller than the predetermined size, the occurrence of particle size segregation of the refractory aggregate can be suppressed, the uniformity of the construction body can be secured, and the strength reinforcement of the metal aggregate is also combined It was newly found that the strength of the refractory can be greatly improved and the cracking of the refractory can be suppressed. This will be described in detail below.

When a large amount of metal aggregate was included in the refractory aggregate, a fillability test was conducted by changing the maximum diameter of the refractory aggregate in order to determine the limit value of the fillability of the refractory aggregate. .
Specifically, after a mold with an inner diameter of 200 mmφ x height of 300 mm is mounted and fixed on a vibration mount on which a Eurus motor is installed, a metal fiber of SUS310 with a diameter of 0.5 mm and a maximum length of 25 mm is hung on the mold. 35% by weight was pre-filled. Subsequently, with respect to 100 parts by mass of the alumina-magnesia refractory powder having a maximum particle size of 3.35 mm, 2.0 mm, 1.0 mm, 0.85 mm, 0.6 mm, 0.3 mm, and 0.106 mm, the outer coating is applied. Was kneaded with 8.5 parts by mass of added water to obtain a slurry. After that, after kneading slurry was cast into the mold pre-filled with metal fibers while pouring kneaded slurry, the mold was removed from the vibration mount, air-cured for 10 hours, and then dried at 110 ° C. The sample was dried for 15 hours and unframed, and the apparent porosity of the molded body was measured and the presence or absence of unfilled sites was investigated.

As a result, as shown in FIG. 2, it was found that when the maximum diameter of the refractory aggregate is 0.85 mm or less, the apparent porosity can be significantly reduced. It can be seen that this confirms that the number of unfilled portions of the refractory aggregate is drastically reduced and the generation of voids in construction work can be avoided.
The amorphous refractory of the present invention is characterized in that it contains a large amount of metal aggregate, but, as described in the production method described later, the addition of an amount that does not precipitate and separate the metal aggregate during curing and curing. In order to do this, an amount of metal aggregate that can fill the original construction space is required.

In the present invention, in order to obtain high strength, it is necessary to fill the entire volume of the refractory with the metal aggregate. For this purpose, the content of the metal aggregate is set to 20% by mass or more. It is preferably 30% by mass or more, and more preferably 40% by mass or more.
On the other hand, in order for the amorphous refractory to be sufficiently filled in the metal aggregate and to exhibit fire resistance, the content of the metal aggregate is required to be 60% by mass or less.
The shape of the metal aggregate is not particularly specified, and may be any of a dendritic shape, a flake shape, or a fiber shape, which will be described later.
Incidentally, the metal used for the metal aggregate is not particularly limited as long as it is a metal having a high melting point and a high tensile strength up to a high temperature because it is applied to a high-temperature molten metal. For example, iron, stainless steel, tungsten, molybdenum, etc. Are preferably used.

On the other hand, the type of the refractory aggregate is not particularly limited, and it has been confirmed that the effect of the present invention can be obtained by setting the maximum particle diameter to 0.85 mm or less. Also, regardless of the type and shape of the metal aggregate, similarly, by setting the maximum particle diameter to 0.85 mm or less, the effect of the present invention that the apparent porosity of the construction body can be reduced as shown in FIG. Make sure you can get.
In addition, a slurry-like kneaded material can be easily obtained by setting the maximum particle size of the refractory aggregate to 0.85 mm or less, which is also preferable from this viewpoint.
Incidentally, the lower limit value of the maximum particle diameter of the refractory aggregate is not particularly specified, but it is preferably 0.31 mm or more in consideration of the pulverization cost and the like.
On the other hand, when the maximum particle size exceeds 0.85 mm, it becomes difficult to fill the space of the metal aggregate with the refractory aggregate, and it remains as a post-construction space, the apparent porosity of the construction body increases, and high strength is obtained. It becomes difficult to be.

The castable refractory according to the present invention is different from concrete in order to prevent explosion when used in a high temperature environment. . The amount is preferably 9 parts by mass or less, and more preferably 8 parts by mass or less.
In order to control the water content to 10 parts by mass or less, it can be appropriately carried out by curing and drying, which are known means described later.

Refractory aggregates include alumina, magnesia, siliceous, silica-alumina, alumina-magnesia, alumina-spinel, alumina-spinel-magnesia, clay, chrome, waxy, zircon, zirconia 1 type or 2 types or more of carbonaceous, carbonaceous, silicon carbide, magnesia, magnesia-carbon, alumina-carbon, alumina-silicon carbide-carbon, alumina-magnesia-carbon, zirconia-carbon Can be selected and used.
That is, a high-strength refractory can be obtained by using any one of these refractory aggregates according to the use environment.

As the shape of the metal aggregate, a dendritic shape, a flake shape, a fiber (metal piece) shape or the like is recommended.
The dendritic shape means a shape in which the tip branches into a plurality of like a capillary, and is very effective for castable reinforcement by a metal branch stretched in three dimensions. In the case of a dendritic shape, the cross-sectional area of one branch is preferably 0.05 mm ² or more and 1 mm ² or less, and the maximum diameter of the aggregate is 1.0 mm or more and 50 mm or less from the filling property of the metal aggregate. It is preferable that
Incidentally, the dendritic metal aggregate can be produced by, for example, shearing a plurality of commercially available wires in a wire shape.

In the case of flakes, the maximum length is preferably 1.0 mm or more and 50 mm or less, and the cross-sectional area is 0.5 mm ² or more and 10 mm ² or less. If the cross-sectional area and length exceed the above range, uniform dense filling of the metal aggregate becomes difficult and high strength is difficult to obtain, so the above range is preferable.
On the other hand, when the maximum length and the length are less than the above range, it is difficult to contribute to the cross-linking of the refractory particles and the reinforcing effect is hardly exhibited. Therefore, it is preferable that the size be equal to or greater than the size that satisfies the filling property and exhibits the reinforcing effect.
Incidentally, the flaky metal aggregate can be produced by cutting a metal foil rolled with a cross-sectional area of 0.5 mm ² or more and 10 mm ² or less into a length of 1.0 mm or more and 50 mm or less.

Alternatively, the shape of the metal aggregate may be a shape produced by cutting the metal base material. Here, the shape of the metal aggregate formed by cutting the metal base material is generally expressed in this way because it is difficult to define the shape.
Examples of the method for cutting the metal base material include a case where a hole is made in the metal base material, a case where the metal base material is cut, and a case where a part of the metal base material is scraped off. Here, the shape of the metal aggregate includes all the shapes produced in the above cases (may be described as chips).
In addition, the size of the chopped metal aggregate is preferably, for example, from a cross-sectional area of 0.5 mm ² to 10 mm ² and a length of 0.5 mm to 30 mm. If the cross-sectional area or length exceeds the above range, uniform dense filling of the metal aggregate becomes difficult and high strength is difficult to obtain, so the above range is preferable.

In the case of a fiber shape, the cross-sectional area is preferably 0.05 mm ² or more and 1 mm ² or less, and the length is preferably 1.0 mm or more and 50 mm or less. If the cross-sectional area or length exceeds the above range, uniform dense filling of the metal aggregate becomes difficult and high strength is difficult to obtain, so the above range is preferable.
Incidentally, the fiber-like metal aggregate can be produced, for example, by shearing a commercially available wire to the above length.

Next, the manufacturing method of the refractory formed using the amorphous refractory of this invention is demonstrated.
The present invention is characterized in that after a metal aggregate, a refractory aggregate and water are kneaded, they are poured into a mold and cured and dried. In particular, when the metal aggregate is in the form of flakes or fibers, the metal aggregate without voids is uniformly distributed in the space by pouring it into the mold as a slurry in which the metal aggregate, the refractory aggregate and moisture are mixed in advance. A densely packed amorphous refractory can be easily constructed, which is preferable.
By the way, according to the degree of strength of the irregular refractory required in the planned construction space, the desired amount of metal aggregate to be filled is set appropriately, and according to the amount of this desired metal aggregate Thus, it is preferable to mix the refractory aggregate and water, pour them into a mold after kneading, and dry them by curing.

In addition, in the present invention, apart from the case where construction is performed after mixing and kneading each of the above-mentioned aggregates and water, only the metal aggregate is put in the mold in advance and the construction space is filled with the metal aggregate, and then fireproofing. It is also possible to pour a slurry obtained by kneading the active aggregate and water into the mold and to dry it.
In the case of this method, it is effective when the specific gravity difference between the metal aggregate and the refractory aggregate is high, and since only the metal aggregate is filled in advance, segregation due to the sinking of the metal aggregate can be prevented.
If casting is performed while applying vibration to the mold, it is preferable because the filling proceeds efficiently. Particularly, when the metal aggregate is in the form of chips or fibers.
Curing and drying may be carried out by a known method, and moisture is adjusted to 10% by mass or less with respect to the mass of the refractory material in order to prevent explosion during use.

A binder may be added to the amorphous refractory according to the present invention as necessary. As the binder, any one or more of a sintering agent, a dispersing agent, a surfactant, a curing agent, a curing regulator and the like may be added. In order to prevent disintegration due to curing shrinkage, the total binder content is preferably 65% by mass or less.
As the sintering agent, ultrafine alumina, ultrafine SiC, ultrafine SiO ₂ or the like can be used.
Dispersants include sodium pyrophosphate, sodium tripolyphosphate, sodium tetrapolyphosphate, sodium hexametaphosphate, sodium humate, sodium carbonate, sodium silicate, organic sodium phosphate, sodium polyacrylate, sodium citrate, sodium tartrate, tannic acid Examples include sodium, sodium β-naphthalene sulfonate, sodium alkyl allyl sulfonate, and the like.

Examples of the surfactant include sodium tripolyphosphate, sodium hexametaphosphate, sodium ultrapolyphosphate, acidic sodium hexametaphosphate, sodium borate, sodium citrate, carboxyl group-containing polyether dispersant, sodium tartrate, sodium polyacrylate, sulfone. 1 type (s) or 2 or more types chosen from sodium acid etc. can be used.
The hardener is most preferably alumina cement, but is not limited thereto, and for example, one or more selected from sodium silicate, silica sol, alumina sol, aluminum phosphate, aluminum lactate and the like can be used.

  In order to obtain a suitable pot life, a curing regulator can be added as necessary, for example, boric acid, oxalic acid, citric acid, gluconic acid, ammonium borate, sodium ultrapolyphosphate, One or more selected from lithium carbonate, slaked lime, lithium salt, oxycarboxylic acid, dicarboxylic acid, monocalcium phosphate, resorcin, and the like can be used.

[ Reference Example 1]
An amorphous refractory obtained by adding moisture to an aggregate consisting of a metal aggregate and a fireproof aggregate was applied to the lower tundish nozzle, tuyere block and tundish cover, and was used in the actual furnace. . The details are described below.
A mold frame 2 (outer diameter 310φ × inner diameter 90φ × height 350 mm) for the tundish lower nozzle shown in FIG. 1A is mounted and fixed on the vibration table 1 on which the Eurus motor is installed, and then the SUS310 is mounted on the mold. Of metal fiber was pre-filled.
Subsequently, 100 parts by mass of alumina-magnesia refractory powder having a maximum particle size of 0.3 mm was kneaded with 8.0 parts by mass of added water to create a slurry.

After that, kneading slurry was cast while applying 0.3 G vibration in a mold pre-filled with metal fibers, and then the mold was removed from the vibration table, and after curing for 10 hours in an air oven at 110 ° C. And dried for 15 hours.
Then, it installed as a lower nozzle of a 60-ton capacity tundish, and after heating up for 1 hour and 30 minutes, 360 tons of molten steel were completely cast in 240 minutes.
Also, the tundish tuyere shown in FIG. 1 (B) is manufactured using the tuyere mold 3 in the same manner as in the case of the above-mentioned tundish lower nozzle, and as a tuyere tuyere tuyere. In the first application, the application was started after heating for 1 hour 30 minutes. After that, 58 heat was used and replaced systematically.

On the other hand, SUS304 metal fiber is pre-filled in a rectangular parallelepiped tundish cover having a width of 2000 mm, a length of 3000 mm, and a thickness of 212 mm, and 100 parts by mass of an alumina-silica refractory powder having a maximum particle diameter of 0.5 mm. Then, a refractory powder slurry kneaded with an added moisture of 7.9 parts by mass was cast and molded.
It was pre-dried until the surface temperature reached 600 ° C. and used in an actual furnace. These results are summarized in Table 1.
In addition, as a comparative example, the maximum diameter of the refractory particles is 1.2%, 2.0mm, 5.66mm, and 3.35mm, respectively. Table 2 shows the case of metal fiber together with the results in the actual furnace with the lower nozzle, tuyere and tundish cover that were added by 3% by mass and kneaded at the same time.
For the bulk specific gravity and porosity of the general physical properties in Table 1 and Table 2, the test piece after molding specified in JIS R 2553 is used, and the compressive strength is in accordance with JIS R 2553. Based on each measurement.

[ Reference Example 2, Example 1 ]
In the case of metal aggregates other than metal fibers, they were applied to the nozzle under the tundish and used in an actual furnace. The details are described below.
As in the case of the metal fiber, the mold frame 2 (outer diameter 310φ × inner diameter 90φ × height 350 mm) for the tundish lower nozzle shown in FIG. 1 (A) is mounted and fixed on the vibration table 1 on which the Eurus motor is installed. After that, a wire having 10 pieces of alumina-magnesia refractory powder having a maximum particle size of 0.3 mm, SUS310 flaky cutting powder, and a wire rod having a diameter of 0.5φ was cut into a length of 25 mm. Add 35% by mass of dendritic metal aggregate, and 8.0 parts by mass, 8.3 parts by mass and 8.2 parts by mass, respectively, with respect to 100 parts by mass of refractory powder of alumina-magnesia. Simultaneously kneading with part of the added water.

Then, after casting each kneaded material into the mold 2 while applying 0.3 G vibration, the mold 2 is removed from the vibration table 1 and air-cured for 10 hours, and then dried in a drying furnace at 110 ° C. for 15 hours. To remove the frame.
Thereafter, it was installed as a lower nozzle of a 60-ton capacity tundish, and both were heated for 1 hour and 30 minutes and then used for casting 360 tons of molten steel per heat. These results are shown in Table 3.

As shown in Tables 1 to 3, with the lower nozzle, no cracks were observed on the appearance / cut surface, and good results were obtained. As the form of the metal aggregate, the dendritic shape was the best, followed by high durability in the order of flakes and fibers.
No cracks were observed in the appearance and inside of the tuyere, and all the samples were sintered after use and increased in strength.
On the other hand, in the tundish cover (TD cover), in the comparative example of the prior art, peeling damage around the opening portion occurs at an early stage, but in the product of the present invention, peeling damage does not occur even when the heat frequency is 7 times or more. Life extension could be achieved.

Explanatory drawing which shows the outline | summary at the time of shaping | molding of a tundish lower nozzle and the shaping | molding of a tundish tuyere. Explanatory drawing which shows the relationship between the maximum diameter of a refractory aggregate and the apparent porosity of a construction body.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Vibration table with Eurus motor, 2 ... Lower nozzle form, 3 ... Tuyere form

Claims (5)

An aggregate composed of a dendritic metal aggregate having a shape of 20 parts by mass or more and 60 parts by mass or less, and a refractory aggregate having a maximum particle diameter of 0.85 mm or less and 40 parts by mass or more and 80 parts by mass or less. In addition, 10 parts by mass or less of water is added to 100 parts by mass of the refractory aggregate, and the dendritic metal aggregate is sheared over a plurality of wires. An unshaped refractory having a shape in which the tip is branched into a plurality of like a capillary and having a cross-sectional area of one branch of 0.05 mm ² or more and 1 mm ² or less. .   The refractory aggregate is composed of alumina, magnesia, siliceous, silica-alumina, alumina-magnesia, alumina-spinel, alumina-spinel-magnesia, clay, chrome, waxy, zircon, zirconia One or more of carbonaceous, carbonaceous, silicon carbide, magnesia, magnesia-carbon, alumina-carbon, alumina-silicon carbide-carbon, alumina-magnesia-carbon, or zirconia-carbon The amorphous refractory according to claim 1, wherein the refractory is an amorphous refractory.   A method for producing a refractory, comprising mixing the metal aggregate according to claim 1 or 2, the refractory aggregate, and water, then pouring the mixture into a mold and curing and drying.   The refractory material manufacturing method according to claim 3, wherein after the kneading of the desired amount of the metal aggregate filling the construction space, the refractory aggregate and water, the mixture is poured into a mold and cured and dried. Method.   The metal aggregate according to claim 1 or 2 is put into a mold in advance and the construction space is filled with the metal aggregate, and then a slurry obtained by kneading the refractory aggregate and water according to claim 1 or 2 is used. A method for producing a refractory material, which is poured into the mold and cured and dried.

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