JP2006176363A - Monolithic refractory for blast furnace main trough metal line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a monolithic refractory for a blast furnace main trough metal line which can be used over a long period of time even if it is applied to a metal line part of a blast furnace main trough that is installed on a cast house of a blast furnace, which contains graphite, and which is excellent in corrosion resistance to slag and spalling resistance. <P>SOLUTION: Above problem can be solved by a monolithic refractory for a blast furnace main trough metal line in which the monolithic refractory is composed of Al<SB>2</SB>O<SB>3</SB>-MgO-SiC-a carbonaceous material, and into which pre-molded granules that contain Al<SB>2</SB>O<SB>3</SB>, MgO and graphite are added as aggregate. Wherein it is preferable that in the composition of the granule, the mass ratio of MgO/Al<SB>2</SB>O<SB>3</SB>is set in a range of 0.2-0.7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an irregular refractory material suitable for a metal line part of a blast furnace main body, which is a flow path of hot metal produced from the blast furnace and discharged from the blast furnace, and more specifically, has excellent spall resistance and cracks during use. It relates to irregular refractories that are rarely generated.

  In recent years, among the refractories used in the steel industry, many of the regular refractories used in particularly high-temperature facilities contain graphite. This is because high durability can be expected by utilizing the properties of graphite itself, such as heat resistance, corrosion resistance to slag, volume stability due to low thermal expansion, and excellent spall resistance. However, in an irregular refractory, the amount of water required for kneading increases due to the water repellency that is a characteristic of graphite, and a dense construction body cannot be obtained. It is difficult to use and is not used as well as regular refractories.

However, techniques for overcoming this water repellency have also been proposed. For example, Patent Document 1 discloses a pellet in which scaly graphite and / or carbonaceous fibers and a refractory aggregate are pressure-molded using a resin in an amorphous refractory composed of a refractory powder part and a resin liquid part. Has been disclosed as a part of the refractory powder part. In this method, the water repellency of graphite is reduced by the fireproof aggregate, and even a carbon material having a large aspect ratio such as scaly graphite and carbon fiber can be used without hindering kneading, There is a feature that a dense construction body can be obtained. Patent Document 2 discloses that Al ₂ O ₃ and graphite are granulated by a pelletizer using a resin as a refractory used in an electric steel slag, and this granulated body is used as an aggregate. _{A 2} O ₃ —SiC—carbonaceous castable is disclosed.

However, these amorphous refractories have little effect on improving the durability against hot metal, and are used as refractories for main blast furnaces for flowing hot metal, especially for refractory metal lines. It was impossible to use for a long time.
JP-A-6-287072 JP-A-11-236273

  The present invention has been made in view of the above circumstances, and the object of the present invention can be used over a long period of time even if it is constructed on the metal line part of the blast furnace main shaft installed in the blast furnace casting floor, An object is to provide an amorphous refractory for a blast furnace main metal line containing graphite and having excellent corrosion resistance and spall resistance to slag.

An amorphous refractory for a blast furnace main metal line according to the first invention for solving the above-mentioned problem is an amorphous refractory for a blast furnace main metal line of Al ₂ O ₃ —MgO—SiC—carbonaceous. A granulated body containing Al ₂ O ₃ , MgO and graphite, which is molded in advance, is added as an aggregate.

The amorphous refractory for the blast furnace main metal line according to the second invention is the first invention, wherein the composition of the granulated material is in the range of MgO / Al ₂ O ₃ mass ratio of 0.2 to 0.7. It is characterized by being.

  According to the amorphous refractory for a blast furnace main metal line according to the present invention having the above-described configuration, graphite and MgO which are originally excellent in spalling properties are added as aggregates in a state of being molded into a granulated body. The water repellency of the slag is suppressed, so that it does not interfere with the construction work of the irregular refractory, and the corrosion resistance to the slag remains as it is, providing excellent spall resistance and stable over a long period of time. It is possible to use it, and industrially beneficial effects such as reduction of refractory costs are brought about.

The present invention will be specifically described below. The amorphous refractory for a blast furnace main metal line according to the present invention is an Al ₂ O ₃ —MgO—SiC in which a granulated body containing Al ₂ O ₃ , MgO and graphite is added as an aggregate. -Carbonaceous amorphous refractories.

Here, when the Al ₂ O ₃ and MgO contained in the monolithic refractories formed a spinel monolithic refractory of Al ₂ O ₃ -MgO-SiC- carbonaceous in the present invention, the spinel - Al ₂ O ₃ —SiC—Substantially the same as a carbonaceous amorphous refractory. The blast furnace head (also referred to as “Otsuchi”) is a firewood that is placed on the blast furnace casting floor in contact with the blast furnace outlet hole, and the hot metal and slag discharged from the outlet hole in a parabolic manner are dropped. As a result, the refractory material should be worn more severely than other hot metal and slag irons due to vigorous stirring and flow of hot metal and slag. In addition, the metal line portion where the molten metal and slag flow down by mixing is particularly severe, and there is a demand for an amorphous refractory for a blast furnace main metal line with high durability.

As a granule containing Al ₂ O ₃ , MgO and graphite used as an aggregate, a spinel-graphite granule, a spinel-Al ₂ O ₃ -graphite granule, and Al ₂ O ₃ —MgO—graphitic granules are preferred, but spinel-Al ₂ O ₃ —MgO—graphitic granules, spinel-MgO—graphitic granules, etc. can also be used. . In short, any granule containing an Al ₂ O ₃ component, an MgO component, and graphite can be used.

That is, the amorphous refractory for a blast furnace main metal line according to the present invention uses one or more of the above granulated materials as an essential constituent material as an aggregate, and refractories such as SiC, Al ₂ O ₃ , and spinel. object material, other pitches as required, carbon black, metallic Si powder, metallic Al powder, Al-Si alloy powder, an antioxidant, such as B ₄ C powder, silica fine, binders such as alumina cement, and, It is prepared by mixing various dispersing agents at a predetermined blending ratio. It can also be produced by a monolithic refractory of one or more granules of the spinel -Al ₂ O ₃ -SiC- carbonaceous are mixed in a predetermined mixing ratio.

The spinel in the present invention is a substance called spinel, and the chemical structural formula of an ideal composition is represented by MgAl ₂ O ₄ (or “MgO · Al ₂ O ₃ ”). MgO / Al ₂ O _{3 has a} mass ratio of 0.395, but there are very few spinels with an ideal composition in nature, and it can be used without problems even if it is not an ideal composition as a refractory material. Therefore, in the present invention, even if Al ₂ O ₃ or MgO is excessively contained, if the MgO / Al ₂ O ₃ mass ratio is in the range of 0.3 to 0.5, these All are defined as spinel.

The granulated body is produced, for example, by a combination of spinel powder and graphite powder, a combination of spinel powder, Al ₂ O ₃ powder and graphite powder, or a combination of Al ₂ O ₃ powder, MgO powder and graphite powder. . As graphite, scaly graphite or the like can be used. Corrosion resistance to blast furnace slag is the best combination of spinel and graphite among the above combinations, but spinel and Al ₂ O ₃ if the same composition as the combination of spinel and graphite can be obtained. Sufficient durability can be obtained by either a combination of graphite and graphite, or a combination of Al ₂ O ₃ —MgO—graphite.

  The particle size of the granule to be used as the aggregate is not particularly limited, and can be used at 1 mm or more and 10 mm or less, which is a coarse particle member of an ordinary amorphous refractory, and further larger. It is also possible to use it as coarse particles at 10 mm or more and 50 mm or less.

The chemical composition of the granule, MgO / Al ₂ O ₃ mass ratio is preferably in the range of 0.2 to 0.7. If the MgO / Al ₂ O ₃ mass ratio is less than 0.2, sufficient corrosion resistance against blast furnace slag cannot be obtained. Further, even if the MgO / Al ₂ O ₃ mass ratio exceeds 0.7, sufficient corrosion resistance against blast furnace slag cannot be obtained. Preferably, the MgO / Al ₂ O ₃ mass ratio, which is a theoretical spinel structure, is in the vicinity of 0.4. On the other hand, the concentration of graphite in the granulated body is about 5 to 30% by mass. When the amount of graphite is less than 5% by mass, the effect of improving the spall resistance of graphite becomes difficult to be exhibited, and when it exceeds 30% by mass, it becomes difficult to form a granulated body. By setting the preferable concentration of graphite within this range, the preferable concentration range of MgO and Al ₂ O ₃ is naturally determined from the preferable MgO / Al ₂ O ₃ mass ratio.

  The granulated body is produced by adding a phenol resin as a binder to constituent particles such as spinel powder and graphite powder, kneading, and pressure granulating. As a method for pressure granulation, it may be molded by using a briquette machine, or may be produced by a method of pressure molding into a corrugated flat plate called compacting, and crushing and classification. After granulation, it is desirable to develop strength by heating so that it can withstand kneading using water as an aggregate of the irregular refractory.

Granules obtained in this way are made of the above-mentioned refractory raw materials such as SiC, Al ₂ O ₃ and spinel, antioxidants such as pitch, carbon black and metal Si powder, binders such as alumina cement, and various It is mixed with other constituent materials such as a dispersant to make an irregular refractory for the blast furnace main metal line. The blending ratio of the granulated material to be added as an aggregate may be the same as that of a coarse member of a normal amorphous refractory, for example, 40% by mass of the amorphous refractory for a blast furnace main metal line to be produced. What is necessary is just about 70 mass%. As long as the granule is added within this range, corrosion resistance and spall resistance can be exhibited. Of course, it is also possible to add other refractory materials other than the granulated material as an aggregate.

  When used as a refractory for a blast furnace main metal line, after mixing with a mixer, water is added and further mixed, and then casting is performed. After curing, dry and preheat with a gas burner, etc., and serve as the main receiver.

The amorphous refractory for a blast furnace main metal line of the present invention produced in this way is a spinel-Al ₂ O ₃ -SiC-carbonaceous amorphous refractory usually used for a blast furnace main metal line part. Despite the fact that it has almost the same corrosion resistance, it is possible to obtain a dense construction body and at the same time, graphite and MgO, which are inherently excellent in spalling properties, are added as aggregates, so high spalling resistance can also be achieved and used. The occurrence of melting and cracking in the inside is suppressed, and it becomes possible to use it stably over a long period of time.

  Sintered spinel, fused alumina, calcined alumina, magnesia and other refractory powders and scaled graphite are used to prepare a predetermined composition, and a phenol resin is added as a binder to this and kneaded in a universal kneader, Eight types of granulation raw materials (granulation raw materials A to H) were prepared. Table 1 shows the raw materials used in the eight types of granulated raw materials A to H and the blending ratios thereof.

As shown in Table 1, the material of each granulation raw material is that the granulation raw materials A and B are spinel-Al ₂ O ₃ -graphite, and the granulation raw material C is a spinel of 50% by mass MgO-50% by mass Al ₂ O ₃ . -Al ₂ O ₃ - graphite, granulated material D, E, F, G is Al ₂ O ₃ -MgO- graphite, granulated material H are Al ₂ O ₃ - is a graphite. Here, the granulated raw materials A, B, C, D, and E have the MgO / Al ₂ O ₃ mass ratio adjusted so that Al ₂ O ₃ is larger than the theoretical spinel, while the granulated raw materials F, For G, the MgO / Al ₂ O ₃ mass ratio is adjusted so that MgO is larger than the theoretical spinel.

Granules were produced using these granulation raw materials A to H. As a method for producing the granulated material, lens-shaped briquettes having a roll diameter of 114 mm and a roll width of 40 mm were produced for all of the granulated raw materials A to H using a briquette machine of 8 mm, 5 mm, and 3 mm, respectively. Moreover, about the granulation raw material A, it compacted using the corrugated roll with the same machine, and the granulated body of 3-1 mm was produced by grinding | pulverization and classification. Furthermore, for the granulation raw materials A and D, a granule is produced by press molding at a molding pressure of 0.5 t / cm ² using a mold capable of producing a molded product having a diameter of 25 mm and a height of 25 mm. did. The produced granule was heat-treated at 180 ° C. for 3 hours in order to improve the strength.

Using the granulated material after the heat treatment produced from the granulated raw materials A to G, these granulated materials are fused with spinel, fused alumina, calcined alumina, SiC, pitch, metal Si, alumina cement, carbon. Black and the like were added to prepare 10 types of Al ₂ O ₃ —MgO—SiC—carbonaceous refractory main metal line amorphous refractories (Invention Examples 1 to 10). Table 2 shows the raw materials used in the irregular refractories for main metal lines of Invention Examples 1 to 10 and the blending ratio thereof. Here, in Invention Examples 8 and 9 using a press-molded product having a diameter of 25 mm, the press-molded product was molded at the center of the molded body sample to be produced, and the evaluation test was performed at that site. In addition, the naphthalenesulfonic acid and polyether polycarboxylic acid Na salt shown in Table 2 are dispersants for alumina, and polyoxyethylene oleyl ether is a dispersant for graphite.

Further, as comparative examples, without using these granulated bodies, Al ₂ O ₃ —MgO—SiC—carbonaceous amorphous refractory (Comparative Example 1) and Al ₂ O ₃ —SiC—carbonaceous amorphous A refractory (Comparative Example 2) was produced. Furthermore, the amorphous refractory material (Comparative Example 3) produced using the granulated body H in which MgO is not contained in the granulated body was also prepared. The raw materials used and the blending ratio thereof in Comparative Examples 1 to 3 are also shown in Table 2 described above.

  Water was added to these irregular refractories and kneaded, and the flow value after 15 taps was measured. In Invention Examples 1 to 10 and Comparative Example 3 in which the granulated material was blended, the amount of mixed water was increased by 1% by mass compared to Comparative Examples 1 and 2 in which no granulated material was blended. Thereafter, it was molded into a 40 mm × 40 mm × 160 mm sample and a 78 (48) mm × 35 mm × 160 mm sample, and left to stand after being vibrated for 1 minute. After 1 day, it was dried at 110 ° C. for 24 hours. After drying, a bending strength measurement test, a porosity measurement, a slag erosion test, and a spall resistance evaluation test were performed.

  The bending strength was measured with a Michaelis double lever type bending test apparatus according to JIS-R2553 (castable refractory strength test method) using a sample of 40 mm × 40 mm × 160 mm. The porosity was measured using a sample after a bending test according to the vacuum method of JIS-R2205 (measurement method of apparent porosity / water absorption / specific gravity of refractory bricks).

  The slag erosion test was conducted by the high frequency lining method. That is, a 78 (48) mm × 35 mm × 160 mm sample was subjected to reduction firing at 1000 ° C. for 3 hours, and the resulting fired body was made into 8 groups, in which 6.8 kg of pig iron was dissolved, and 1 hour The erosion test of slag was carried out at 1600 ° C. for 3 hours while adding 200 g of granulated blast furnace slag per unit. The slag was replaced every hour. At this time, the sample of Comparative Example 1 was always put in the eight samples, and the erosion test was performed. From the dimensional change before and after the test, the erosion index was obtained using the Comparative Example 1 as 100.

  Evaluation of the spall resistance was carried out by reducing and firing a sample of 40 mm × 40 mm × 160 mm at 1400 ° C. for 3 hours, and the obtained fired product was placed in a 1200 ° C. furnace atmosphere in which Ar gas was flowed at 5 liters / minute. Put it, hold it for 30 minutes, and then cool it with water, measure the elastic modulus before and after that, and set the ratio of “elastic modulus after thermal shock / elastic modulus before thermal shock” as the residual elastic modulus ratio. It was judged that the closer to 1, the better the spall resistance.

  The results of these investigations are also shown in Table 2 described above. As shown in Table 2, the bending strength of the dried body tended to decrease in Invention Examples 1, 3 to 7, 10 and Comparative Example 3 using briquette granules. Moreover, the porosity of the dried body was almost the same in both the inventive examples and the comparative examples.

The melt index in Invention Examples 1 to 9 was almost the same as that of Comparative Example 1, and was much smaller than that of Al ₂ O ₃ —SiC—carbonaceous amorphous refractory (Comparative Example 2). Further, in Invention Example 10 having a large amount of MgO in the granulated body, the melting index was larger than that in Comparative Example 1, but the melting index was smaller than that in Comparative Example 2. In Comparative Example 3 in which the granulated body did not contain MgO, the melting loss index was extremely large as compared with Comparative Example 1, and good corrosion resistance was not obtained.

  Regarding the spall resistance, in Examples 1 to 10 and Comparative Example 3 using the granulated body, the residual elastic modulus ratio is larger than those of Comparative Examples 1 and 2 not including the granulated body. It was confirmed that the spall resistance was improved by adding.

Claims (2)

An amorphous refractory for a blast furnace main metal line of Al ₂ O ₃ —MgO—SiC—carbonaceous, and a pre-formed granule containing Al ₂ O ₃ , MgO and graphite is an aggregate. An unshaped refractory for the blast furnace main metal line, characterized by being added as _{2. The} amorphous refractory for a blast furnace main metal line according to claim 1, wherein the composition of the granulated material has an MgO / Al ₂ O ₃ mass ratio in the range of 0.2 to 0.7. .