KR20050064055A - Batch composition of blow pipe refractories - Google Patents

Abstract

The present invention relates to a blow pipe refractory composition, wherein the particle size is 0.5 to 3 mm, 28 to 39% by weight of lite, 22 to 25% by weight of lite with a particle size of 3 to 10 mm, 17 to 22% by weight of sintered alumina powder, titanium oxide 5 It comprises 8 to 8% by weight, 6 to 8% by weight of chromium oxide, 4 to 6% by weight of alumina cement and 7 to 10% by weight of ceramic fiber, the blast pipe refractory composition according to the invention is sintered the mullite and the bonding portion as aggregate By employing titanium oxide and chromium oxide as accelerators, there is an effect excellent in heat insulation and corrosion resistance.

Description

Batch Composition of Blow Pipe Refractories

The present invention relates to a blowpipe refractory composition. More specifically, the present invention relates to a blower pipe refractory composition having excellent heat insulation and erosion resistance by adopting titanium oxide and chromium oxide as sintering accelerators of mullite as the aggregate.

The hot air supplied to the blast furnace is produced in the hot blast furnace and supplied to the inside of the blast furnace through the blowhole, and since the blower tube must continuously supply high temperature hot air, there is a high risk of heat accumulation. It should be stable at high temperature without cracking caused by expansion and contraction. And sometimes pulverized coal, slack, molten iron, etc. in the blast furnace often penetrates and damages the refractory, so corrosion resistance is also required.

Japanese Patent Laid-Open Publication No. Hei 9-157045 discloses a heat insulating castable manufactured by using hollow particles of highly refractory ceramics as aggregate.

In addition, Japanese Patent Laid-Open Publication No. Hei 10-1373 discloses an insulating caster prepared by adding calcined lime, ultrafine silica powder, ceramic fiber, and foaming agent to the main raw materials of alumina and Murite refractory aggregate and transition alumina. On the blog is published.

However, these are all related to the insulation refractory used in the tread dish for continuous casting and the cover of the ladle which is the molten steel transportation container in contact with the industrial furnace and molten steel. There was a problem in that refractory damage suppression at the site where erosion resistance of the mixture is required is not a fundamental solution.

The present invention to solve the above problems, Blower refractory composition with excellent heat insulation and erosion resistance by using mulite which has relatively low thermal conductivity and good thermal insulation effect as aggregate, and adding a small amount of titanium oxide and chromium oxide as sintering accelerator of joint to form strong dense structure to suppress erosion. The purpose is to provide.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention is a particle size of 0.5 to 3mm 28 to 39% by weight; 22 to 25% by weight of lite, having a particle size of 3 to 10 mm; 17 to 22% by weight of sintered alumina fine powder; Titanium oxide 5 to 8% by weight; Chromium oxide 6-8 wt%; 4 to 6% by weight of alumina cement; And 7 to 10% by weight of ceramic fiber; provides a refrigeration tube refractory composition comprising a.

The length of the ceramic fiber may be 3 to 5mm.

Hereinafter, the present invention will be described in detail.

Blowing pipe refractory composition of the present invention is used as the aggregate using a relatively low thermal conductivity and a good thermal insulation effect of 28 to 39% by weight of the Mourite of 0.5 to 3mm and 22 to 25% by weight of the Mourite of 3 to 10mm 17 to 22% by weight of sintered alumina fine powder as well as 5 to 8% by weight of titanium oxide and 6 to 8% by weight of chromium oxide are added as a sintering accelerator of the bonding part to form a firm dense structure to suppress erosion and to increase the bond strength. 4 to 6% by weight of alumina cement is added to increase, and 7 to 10% by weight of good toughness ceramic fiber is added to prevent cracking caused by expansion and contraction.

Mullite (Mullite, 3Al ₂ O ₃ .2SiO ₂ ) used in the present invention is more resistant to erosion than alumina, but is used as aggregate because of its fire resistance and low thermal conductivity. In order for the lite to exhibit physical properties such as optimum corrosion resistance, the structure of the construction body should be the closest packing structure, in which case it becomes difficult for molten material such as slag and molten iron to penetrate. However, as described above, when the structure of the construction body is made of the closest packing structure, the erosion resistance is improved, but the heat insulation is lowered.

Therefore, the appropriate amount of the lite should be used according to the particle size, for example, it is preferable to use 28 to 39% by weight of the Moulite of 0.5 to 3mm and 22 to 25% by weight of the Mourite of 3 to 10mm Do. If the particle size is less than or exceeded, there is a problem that the thermal conductivity is increased, so that the thermal insulation is poor or the erosion resistance is lowered so that both characteristics cannot be satisfied.

High purity sintered alumina fine powder used in the present invention serves to suppress the penetration of molten iron and slack by densifying the bonding portion of the refractory. In addition, artificial alumina such as sintered alumina, electrolytic alumina, calcined alumina or the like may be used depending on the production method. In addition, the particle size of the sintered alumina can be used that is 0.044mm.

The fine sintered alumina powder is preferably used in an amount of 17 to 22% by weight. When the amount of the sintered alumina powder is less than 17% by weight, the structure of the construction body is not dense, so that the strength is small and erosion resistance is lowered. In this case, since the dispersion effect of the raw material is improved and the amount of water added is reduced, a dense structure is obtained, so that the corrosion resistance is good, but the thermal conductivity is rather high, resulting in a decrease in thermal insulation.

Titanium oxide (TiO ₂ ) used in the present invention serves to promote the sintering of the joining member materials to create a firm structure, the particle size of 0.044mm can be used. The titanium oxide is preferably used in an amount of 5 to 8% by weight, and when the amount is less than 5% by weight, the amount of the titanium oxide is less, so that the sintering promoting effect is lowered. There is a problem that the crack is generated between the aggregate and the coupling portion.

Chromium oxide (Cr ₂ O ₃ ) used in the present invention promotes the sintering of the bonding portion like titanium oxide, and serves to firmly bond the aggregate and the bonding portion, and a particle size of 0.044 mm may be used. The chromium oxide is preferably used in 6 to 8% by weight, when the amount of the chromium oxide is less than 6% by weight, there is a problem in that the strength increase effect due to sintering is reduced and the erosion resistance is lowered. Rather, the sintering promotion effect is too large to cause expansion of the coupling portion, there is a problem that generates a crack between the aggregate and the coupling portion.

Alumina cement used in the present invention serves to increase the bonding strength at room temperature and 1000 ℃ around the refractory. Preferably, the alumina cement is used in an amount of 4 to 6% by weight, and if the amount of the alumina cement is less than 4% by weight, there is a problem that the room temperature bonding strength is lowered. Due to the effect of the calcium oxide (CaO) component contained in the erosion is severe, the structure becomes dense, the thermal conductivity is large, there is a problem that the thermal insulation is inferior.

Ceramic fiber (ceramic fiber) used in the present invention is composed of alumina (Al ₂ O ₃ ) and silica (SiO ₂ ), the ceramic fibers are entangled with each other to increase the bonding strength of the construction body, to suppress the occurrence of cracks, micropores It forms a role to improve the steam outflow.

Since the ceramic fibers are added in small amounts, they do not significantly affect the construction body, but the length of the ceramic fibers affects workability. The length of the ceramic fiber is preferably 3 to 5mm, and if the length is less than 3mm, there is a problem that the effect of improving the bonding force of the construction body is lowered.

The amount of the ceramic fiber is preferably 7 to 10% by weight, and less than 7% by weight of the ceramic fiber has a problem in that the amount of the binding force is reduced. There is a problem that the erosion resistance is reduced because the tissue is not compact.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited to the examples.

Example 1

28% by weight Murite with a particle size of 0.5 to 3mm, 25% by weight Murite with a particle size of 3 to 10mm, 22% by weight of sintered alumina fine powder with a particle size of 0.044mm, 5% by weight of titanium oxide having a particle size of 0.044mm, and a particle size of 0.044 A blow tube refractory composition was prepared by mixing 7 wt% of chromium oxide, 6 wt% of alumina cement, and 7 wt% of ceramic fiber.

Example 2

31% by weight Murite with a particle size of 0.5 to 3mm, 22% by weight Murite with a particle size of 3 to 10mm, 19% by weight of sintered alumina fine powder with a particle size of 0.044mm, 7% by weight of titanium oxide having a particle size of 0.044mm, and a particle size of 0.044 A blow tube refractory composition was prepared by mixing 8 wt% of chromium oxide, 5 wt% of alumina cement, and 8 wt% of ceramic fiber.

Example 3

39% by weight Murite with a particle size of 0.5 to 3mm, 22% by weight Murite with a particle size of 3 to 10mm, 17% by weight of sintered alumina fine powder with a particle size of 0.044mm, 5% by weight of titanium oxide having a particle size of 0.044mm, and a particle size of 0.044 A blow tube refractory composition was prepared by mixing 6 wt% chromium oxide, 4 wt% alumina cement, and 7 wt% ceramic fiber.

Example 4

28% by weight Murite with a particle size of 0.5 to 3mm, 24% by weight Murite with a particle size of 3 to 10mm, 17% by weight of sintered alumina fine powder with a particle size of 0.044mm, 8% by weight of titanium oxide having a particle size of 0.044mm, and a particle size of 0.044 A blow tube refractory composition was prepared by mixing 8 wt% chromium oxide, 5 wt% alumina cement, and 10 wt% ceramic fiber.

Comparative Example 1

8% by weight Murite having a particle size of less than 0.5 mm, 30% by weight Murite having a particle size of 0.5 to 3 mm, 50% by weight Murite having a particle size of 3 to 10 mm, 5% by weight of sintered alumina powder having a particle size of 0.044 mm and alumina cement 7 The weight percent was mixed to prepare a blowpipe refractory composition.

Comparative Example 2

40% by weight of lite with a particle size of 0.5 to 3 mm, 18% by weight of lite with a particle size of 3 to 10 mm, 15% by weight of sintered alumina fine powder with a particle size of 0.044mm, 7% by weight of titanium oxide with a particle size of 0.044mm, and particle size of 0.044 A blowdown tube refractory composition was prepared by mixing 9 wt% chromium oxide, 6 wt% alumina cement, and 5 wt% ceramic fiber.

Comparative Example 3

26% by weight Murite with a particle size of 0.5 to 3mm, 26% by weight Murite with a particle size of 3 to 10mm, 24% by weight of sintered alumina fine powder with a particle size of 0.044mm, 4% by weight of titanium oxide having a particle size of 0.044mm, and a particle size of 0.044 A blow tube refractory composition was prepared by mixing 7 wt% of chromium oxide, 7 wt% of alumina cement, and 6 wt% of ceramic fiber.

[Comparative Example 4]

29% by weight Murite with a particle size of 0.5 to 3mm, 22% by weight Murite with a particle size of 3 to 10mm, 20% by weight of sintered alumina powder with a particle size of 0.044mm, 9% by weight of titanium oxide having a particle size of 0.044mm, and a particle size of 0.044 A blow tube refractory composition was prepared by mixing 9 wt% of chromium oxide, 4 wt% of alumina cement, and 7 wt% of ceramic fiber.

[Comparative Example 5]

29% by weight Murite with a particle size of 0.5 to 3mm, 23% by weight Murite with a particle size of 3 to 10mm, 24% by weight of sintered alumina powder with a particle size of 0.044mm, 7% by weight of titanium oxide having a particle size of 0.044mm, and a particle size of 0.044 A blow tube refractory composition was prepared by mixing 5 wt% chromium oxide, 3 wt% alumina cement, and 9 wt% ceramic fiber.

Experimental Example

After blowing the refractory tube refractory composition having a composition ratio as shown in Table 1 prepared in Examples 1 to 4 and Comparative Examples 1 to 5, and kneaded dry in a universal kneading machine and kneaded for 10 minutes by adding 7% by weight of moisture. . The specimens were molded in a mold of size 40x40x160mm, naturally dried in air for 24 hours, and then dried at 110 ° C. for 24 hours in a dryer. Physical properties of the specimens were measured by the following test methods.

Specific gravity, linearity and bending strength were measured by firing the dried specimens at 1000 ° C. for 3 hours in an electric furnace.

Erosion resistance was maintained at 1500 ° C. for 1 hour using blast furnace slag in a small high frequency induction furnace (capacity 3kg), and then the wire was measured to measure the remaining thickness of the specimen.

Thermal conductivity was measured at 1000 ° C. by the hot wire method using specimens calcined at 1200 ° C. (bottle shaped lead and 3 sheets).

The workability was measured by spreading the kneaded sample into the mold of the fluidity tester and striking it 30 times, and then removing the mold.

Physical property measurement results for Examples 1 to 4 and Comparative Examples 1 to 5 are summarized in Table 1 below.

division Example Comparative example One 2 3 4 One 2 3 4 5 Composition (% by weight) Mourite (particle size; 3 to 10 mm) 25 22 22 24 50 18 26 22 23 Mourite (particle size; 0.5 to 3 mm) 28 31 39 28 30 40 26 29 29 Mourite (grain size; less than 0.5 mm) - - - - 8 - - - - Sintered Alumina (particle size; 0.044mm) 22 19 17 17 5 15 24 20 24 Titanium oxide (particle size; 0.044 mm) 5 7 5 8 - 7 4 9 7 Chromium oxide (particle size; 0.044 mm) 7 8 6 8 - 9 7 9 5 Alumina cement 6 5 4 5 7 6 7 4 3 Ceramic fiber 7 8 7 10 - 5 6 7 9 Properties Linear rate of change (%) (1000 ℃ × 3Hr) -0.12 -0.10 -0.08 -0.09 -0.24 -0.18 -0.20 -0.19 -0.21 Bending strength (㎏ / ㎠) (1000 ℃ × 3Hr) 180 175 160 165 140 150 152 148 145 Corrosion Resistance (Erosion Depth, mm) 3.0 3.2 3.7 3.4 4.9 4.0 4.2 4.3 4.2 Volume specific gravity 2.43 2.42 2.45 2.46 2.59 2.50 2.51 2.53 2.52 Thermal Conductivity (k㎈ / mh ℃) 1.70 1.68 1.71 1.69 1.94 1.78 1.79 1.82 1.80 Workability ◎ ◎ ◎ ◎ × × × × ×

As can be seen in Table 1 above, the air pipe refractory compositions of Examples 1 to 4 prepared using titanium oxide and chromium oxide as aggregates and sintering accelerators of the mullite according to the present invention are bonded differently from the present invention. Excellent workability and strength, and relatively low volume specific gravity and erosion depth, compared to Comparative Example 1, which does not use titanium oxide and chromium oxide as negative sintering accelerators, and the blowing tube refractory compositions of Comparative Examples 2 to 5, which are outside the scope of the present invention. It was found that the thermal conductivity was low. That is, it was found that not only the thermal insulation but also the erosion resistance was excellent.

As described above, the blower pipe refractory composition according to the present invention has excellent thermal insulation and erosion resistance, and thus is a useful invention having an effect of reducing erosion damage caused by pulverized coal, slack, and molten iron, even in long-term use.

While the invention has been described in detail above with reference to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope and spirit of the invention, and such modifications and variations fall within the scope of the appended claims. It is also natural.

Claims (2)

28 to 39% by weight of lite having a particle size of 0.5 to 3 mm; 22 to 25% by weight of lite, having a particle size of 3 to 10 mm; 17 to 22% by weight of sintered alumina fine powder; Titanium oxide 5 to 8% by weight; Chromium oxide 6-8 wt%; 4 to 6% by weight of alumina cement; And 7 to 10% by weight of a ceramic fiber; refrigeration tube refractory composition comprising a. The method of claim 1, Blowing pipe refractory composition, characterized in that the length of the ceramic fiber is 3 to 5mm.