Self-bonding refractory castable for large blast furnace tapping channel as well as preparation method and application of self-bonding refractory castable

Abstract

The invention discloses a self-bonding refractory castable for a large blast furnace tapping channel as well as a preparation method and application of the self-bonding refractory castable. The preparation method of the refractory castable comprises the following steps: 1) fully mixing aluminum powder and titanium powder to obtain premixed fine powder, adding a boric acid solution, stirring, aging, carrying out spray granulation molding to obtain a spray material, and uniformly mixing the spray material with amorphous zirconia powder, andalusite fine powder, calcium hexaluminate fine powder and Suzhou clay fine powder to obtain a premixed matrix material; 2) uniformly mixing the fused sub-white corundum particles, the silicon carbide particles and the aluminum silicate fibers to obtain premixed aggregate; (3) mixing tetraethoxysilane, aluminum dihydrogen phosphate and water, and carrying out hydrolysis reaction to obtain a binding agent; 4, the premixed matrix material, the premixed aggregate and the binding agent are mixed to be uniform, and the refractory castable is obtained.The self-bonding refractory castable for the large blast furnace tapping channel is good in self-bonding performance, high in high-temperature strength, high in thermal shock resistance, high in oxidation resistance and especially suitable for the blast furnace tapping channel of high-vanadium-titanium molten iron.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a self-bonding refractory castable for large blast furnace tapping troughs, its preparation method, and its application. Background Technology

[0002] The blast furnace taphole is a crucial channel for molten iron flow in the ironmaking process, where high-temperature molten iron and slag are separated and enter the steelmaking stage. Therefore, the service performance of the refractory materials used in the blast furnace taphole is fundamental to ensuring the stable operation of the ironmaking process. Furthermore, with the increasing size of blast furnaces in domestic steel enterprises, the traditional refractory materials used in blast furnace tapholes are no longer sufficient to meet the stringent requirements of the various types of blast furnace tapholes today.

[0003] Traditionally, refractory materials used in blast furnace tapping troughs have been based on the Al2O3-SiC-C material system. Al2O3 has a melting point as high as 2050℃ and can exist stably at the temperature of molten iron and blast furnace slag. It has good resistance to alkaline blast furnace slag. The tapping trough must withstand the scouring and erosion of high-temperature molten iron. Therefore, the tapping trough refractory material is required to have good high-temperature hot strength and non-wetting properties of the melt. Common non-oxide SiC can meet this requirement well. The carbon-containing component can significantly improve the thermal conductivity and non-wetting properties of the tapping trough lining, thereby improving its thermal shock resistance and erosion resistance.

[0004] In the industry, generally speaking, furnace volumes exceeding 5000m³ are considered... 3 Blast furnaces with a diameter of 4000~5000m are called ultra-large blast furnaces; 3 Called a large blast furnace; 2000~4000m 3 It is called a medium-sized blast furnace; less than 2000m³ 3 This is referred to as a small blast furnace. Different types of blast furnaces have different smelting conditions, such as smelting time, iron output, and the grade and impurity content of the iron ore. This leads to vastly different requirements for the erosion and corrosion resistance of the tapping trough refractory material. Traditional Al2O3-SiC-C refractories are suitable for small blast furnaces, but cannot meet the performance requirements of tapping troughs in larger furnaces. Traditional blast furnace tapping trough refractory materials contain non-oxide components, which are inevitably prone to oxidation when exposed to air during tapping service. Once the carbonaceous components oxidize and leave pores, their high-temperature performance rapidly weakens or even disappears.

[0005] Current common solutions involve introducing antioxidants, such as Al powder and Si powder, into the refractory material for the taphole, or introducing carbon sources with stronger antioxidant properties, such as graphite, expanded graphite, or other modified carbon sources. These techniques improve the antioxidant properties of the carbon-containing components in the taphole refractory material to some extent, but issues such as the dispersibility of antioxidants and volume effects remain unresolved. Furthermore, with increasing environmental awareness, both the carbon content in refractory materials and the carbon emissions during their service life are showing a decreasing trend.

[0006] Furthermore, the refractory material for blast furnace tapping troughs is a "composite" formed using refractory raw materials with different excellent properties, making the bonding between the various components particularly crucial. Currently, pure calcium aluminate cement or ultra-low cement bonding, micronized powder bonding, and sol-gel bonding are mainly used. The bonding mechanisms of each type of binder differ, each with its own advantages and disadvantages. For example, while pure calcium aluminate cement or ultra-low cement bonding possesses good room-temperature demolding strength, its medium-temperature mechanical properties and high-temperature erosion resistance are relatively weak; micronized powder bonding has certain deficiencies in dispersibility and room-temperature strength; sol-gel bonding exhibits good dispersibility, but its early strength and the presence of surfactants in the sol can easily lead to the formation of low-melting-point phases at high temperatures.

[0007] Therefore, developing carbon-free refractory materials for tapping troughs in large blast furnaces with self-bonding properties can solve a major pain point in the industry. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies in the prior art by providing a self-bonding refractory castable for tapping troughs of large blast furnaces, its preparation method and application. The refractory castable is carbon-free, which can effectively avoid the negative effects of oxidation of carbon-containing components in refractory materials. In addition, it also has self-bonding properties.

[0009] The first aspect of this invention provides a method for preparing a self-bonding refractory castable for a large blast furnace tapping trough, the specific steps of which are as follows: 1) Add aluminum powder and titanium powder to a roller mixer and mix thoroughly to obtain a premixed fine powder. Add boric acid solution to the obtained premixed fine powder, stir evenly, and after aging treatment, spray granulation. The obtained granules are passed through a 0.5mm round hole sieve. Take the sieve-passing material to obtain spray material. Add the obtained spray material to amorphous zirconium oxide powder, andalusite fine powder, calcium hexaaluminate fine powder, and Suzhou clay fine powder in a planetary mixer and mix evenly to obtain a premixed matrix material. 2) Add fused alumina particles, silicon carbide particles and aluminum silicate fibers to a planetary mixer and mix evenly to obtain premixed aggregate; 3) Mix tetraethyl orthosilicate, aluminum dihydrogen phosphate and water to carry out a hydrolysis reaction. After the reaction is completed, seal and let stand to cool to 20~30℃ to obtain a binder; 4) Add the premixed matrix material obtained in step 1), the premixed aggregate obtained in step 2), and the binder obtained in step 3) into a V-type mixer and mix them evenly to obtain a self-bonding refractory castable for large blast furnace tapping troughs.

[0010] According to the above scheme, in step 1), the aluminum powder particle size is 10~25μm, the titanium powder particle size is 15~40μm, and the mass ratio of aluminum powder to titanium powder is 1:0.15~0.4. The mixing time in the roller mixer in step 1) is 25~40 minutes.

[0011] According to the above scheme, the concentration of the boric acid solution in step 1) is 2~4 mol / L, and the amount of boric acid solution added is 5~8 wt% of the premixed fine powder.

[0012] According to the above plan, step 1) aging treatment method is: seal and let stand at 25~30℃ for 20~30 minutes.

[0013] According to the above scheme, in step 1), the amorphous zirconia powder (ZrO2 content ≥ 99wt%) has a particle size ≤ 20nm; the andalusite fine powder has a particle size ≤ 60μm and an Fe2O3 content ≤ 0.3wt%; the calcium hexaaluminate fine powder has a particle size ≤ 50μm; and the Suzhou clay fine powder has a particle size ≤ 75μm. The components and their mass percentages in the premixed matrix material are: spray-dried material 5~12%, amorphous zirconia powder 6~14%, andalusite fine powder 27~45%, calcium hexaaluminate fine powder 32~52%, and Suzhou clay fine powder 3~11%. The mixing time in the planetary mixer in step 1) is 15~20 minutes.

[0014] According to the above scheme, the Al2O3 content of the fused alumina particles in step 2) is ≥98wt%, which is obtained by compounding fused alumina particles of different particle sizes. The particle sizes and mass percentages are as follows: 0.1~0.5mm fused alumina particles, 8~25%, 1~3mm fused alumina particles, 25~43% 4~8mm fused alumina particles, 26~45%, 10~15mm fused alumina particles (12~23%).

[0015] This invention achieves a multiphase composite and discontinuous gradation of fused alumina particles and silicon carbide particles, forming a complementary stack. On the one hand, the silicon carbide particles fill the gaps between the large particles, thus preventing oxidation. On the other hand, the combination of multiple phases forms a thermal expansion match, further improving the anti-stripping performance of the castable.

[0016] According to the above scheme, the SiC content of the silicon carbide particles in step 2) is ≥98wt%, which is obtained by compounding silicon carbide particles with a particle size of 0.5~1mm and silicon carbide particles with a particle size of 3~4mm at a mass ratio of 1:1.5~4.5.

[0017] According to the above scheme, the diameter of the aluminum silicate fiber in step 2) is 20~25μm and the length is 4~8mm.

[0018] According to the above scheme, the mass ratio of the fused alumina particles, silicon carbide particles and aluminum silicate fiber in step 2) is 8~16:1.5~5:1. The mixing time in the planetary mixer in step 2) is 5~8 minutes.

[0019] According to the above scheme, the mass ratio of tetraethyl orthosilicate, aluminum dihydrogen phosphate and water in step 3) is 30~55:2~5:100.

[0020] According to the above scheme, the hydrolysis reaction conditions for step 3) are: react at 65~85℃ for 15~20 minutes.

[0021] According to the above scheme, the mass ratio of the premixed matrix material, premixed aggregate and binder in step 4) is 6~9:13~17.5:1. The mixing time in the V-type mixer in step 4) is 8~10 minutes.

[0022] A second aspect of this invention provides a self-bonding refractory castable for large blast furnace tapping troughs prepared according to the above method. The properties of the self-bonding refractory castable for large blast furnace tapping troughs prepared by this invention are as follows: bulk density at 110℃ for 24 hours is 3.08~3.13 g / cm³. 3 The compressive strength at 110℃ for 24 hours is 63~67MPa; the flexural strength at 1400℃ for 0.5 hours is 12.2~15.6MPa; and the antioxidant index at 1000℃ for 5 hours is 84.2~86.6%.

[0023] A third aspect of this invention provides the application of the aforementioned self-bonding refractory castable for large blast furnace tapping troughs as a refractory material in the field of blast furnace discharge devices. The self-bonding refractory castable for large blast furnace tapping troughs of this invention is particularly suitable for tapping troughs in blast furnaces with high vanadium-titanium molten iron.

[0024] The fourth aspect of the present invention provides a refractory material for a large blast furnace tapping trough prepared according to the above-mentioned self-bonding refractory castable for a large blast furnace tapping trough. The refractory material is prepared by first curing the above-mentioned self-bonding refractory castable for a large blast furnace tapping trough at 25~30℃ for 24~48 hours, then heating it to 100~150℃ for 48~60 hours, then heating it to 1000~1200℃ for 24~48 hours, with the heating rate ≤5℃ / min throughout the process, and finally cooling it to room temperature.

[0025] The self-bonding refractory castable for large blast furnace tapping troughs of the present invention belongs to carbon-free iron trough castables. On the one hand, it improves the oxidation resistance of the material, and on the other hand, it reduces the content of non-oxide components (carbon). Furthermore, it makes full use of the sintering between oxide components to enhance the bonding strength of the castable and improve the high-temperature mechanical properties of the material.

[0026] This invention utilizes a blend of aluminum and titanium powders, forming a surface coating under the action of boric acid as a weak electrolyte. At high temperatures, the aluminum and titanium oxidize and combine to form aluminum titanate, which acts as an antioxidant. Simultaneously, the decomposition and release of boric acid forms aluminum borate whiskers. Through the low expansion effect of aluminum titanate and the toughening effect of the whiskers, the thermal shock resistance and high-temperature erosion resistance of the castable are significantly improved. Furthermore, the nano-amorphous properties of amorphous zirconia powder, synergistically with andalusite for toughening, continuously enhance the high-temperature strength of the castable and prevent high-temperature service cracking and damage, effectively alleviating thermal stress concentration. The high-temperature solid solution of amorphous zirconia powder increases the liquid phase viscosity and also inhibits the formation of low-melting-point substances within the material, effectively improving the bonding performance of the material components. The plate / flaky crystal structure of calcium hexaaluminate and the embedding of aluminosilicate fibers facilitate the release of volatiles from the castable at medium and low temperatures. Simultaneously, the interlocking and pinning effects of the one-dimensional and two-dimensional structures enhance the high-temperature torsional strength and shear stress of the castable, thereby improving the self-bonding and erosion resistance of the taphole castable. This invention utilizes the acid hydrolysis of tetraethyl orthosilicate to form a [-Si-O-Al-] tetrahedral coated network structure. This eliminates the need for cement or other impurity ions as bonding phases, avoiding the formation of high-temperature, low-melting-point phases in refractory materials, and leverages the hardening properties of phosphate ions to achieve early high-strength bonding in the castable.

[0027] The beneficial effects of this invention are as follows: 1. The self-bonding refractory castable for large blast furnace tapping troughs provided by this invention has good self-bonding performance, high high-temperature strength, high thermal shock stability, and strong oxidation resistance, making it particularly suitable for blast furnace tapping troughs with high vanadium-titanium molten iron. 2. The preparation method provided by this invention has simple steps, readily available raw materials, and low cost, making it practically valuable for widespread application. Attached Figure Description

[0028] Figure 1 A comparison chart of the calculated Gibbs free energy results for the oxidation reactions of Al, Ti, Si, ferrous iron, and ferric iron; Figure 2 The image shows the oxidation resistance of the self-bonded refractory castable sample for the tapping trough of a large blast furnace prepared in Example 1. Figure 3 The image shows a cross-sectional SEM image of a self-bonded refractory castable sample for a large blast furnace tapping trough prepared in Example 1. Detailed Implementation

[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0030] The aluminum powder used in this embodiment has a particle size of 10~25μm, the titanium powder has a particle size of 15~40μm, the amorphous zirconia powder has a ZrO2 content of 99wt% and a particle size of 20nm; the andalusite fine powder has a particle size of 60μm and a Fe2O3 content of 0.3wt%; the calcium hexaaluminate fine powder has a particle size of 50μm; and the Suzhou clay fine powder has a particle size of 75μm.

[0031] The Al2O3 content of the fused alumina particles used is 98wt%, which is obtained by compounding fused alumina particles of different sizes. The particle size and mass percentage are as follows: 0.1~0.5mm fused alumina particles 12%, 1~3mm fused alumina particles 25%, 4~8mm fused alumina particles 40%, and 10~15mm fused alumina particles 23%.

[0032] The silicon carbide particles used have a SiC content of 98wt%, and are obtained by compounding silicon carbide particles with a particle size of 0.5~1mm and silicon carbide particles with a particle size of 3~4mm at a mass ratio of 1:3; the aluminum silicate fibers used have a diameter of 20~25μm and a length of 4~8mm.

[0033] Example 1 A self-bonding refractory castable for a large blast furnace tapping trough, the specific steps of its preparation method are as follows: 1) Aluminum powder and titanium powder are mixed at a mass ratio of 1:0.275 and added to a roller mixer and mixed for 30 minutes to obtain a premixed fine powder. 8 wt% of boric acid solution (concentration of 2.5 mol / L) is added to the obtained premixed fine powder and stirred evenly. After being sealed and allowed to stand at 25~30℃ for 25 minutes, the mixture is spray-granulated. The resulting granules are passed through a 0.5 mm round hole sieve, and the sieve-passing material is collected to obtain the spray material. The obtained spray material is mixed with amorphous zirconium oxide powder, andalusite fine powder, calcium hexaaluminate fine powder, and Suzhou clay fine powder at a mass ratio of 6:8:28:40:3 and added to a planetary mixer and mixed for 20 minutes to obtain a premixed matrix material. 2) The fused alumina particles, silicon carbide particles and aluminum silicate fibers are mixed in a mass ratio of 9.38:2.25:1 and added to a planetary mixer and mixed for 5-8 minutes to obtain premixed aggregate; 3) Mix tetraethyl orthosilicate, aluminum dihydrogen phosphate and water at a mass ratio of 40:2:100, stir at 65°C for 20 minutes, seal and let stand to cool to 20~30°C to obtain the binder; 4) The premixed matrix material obtained in step 1), the premixed aggregate obtained in step 2), and the binder obtained in step 3) are mixed in a mass ratio of 7.6:16.2:1 and added to a V-type mixer. After mixing for 10 minutes, a self-bonding refractory castable for large blast furnace tapping troughs is obtained.

[0034] The self-bonding refractory castable for the large blast furnace tapping trough prepared in this embodiment was first cured at 25°C for 24 hours, then heated to 120°C for 48 hours, and then heated to 1000°C for 24 hours. The heating rate throughout the process was ≤5°C / min. Finally, it was cooled to room temperature to obtain the refractory material for the large blast furnace tapping trough.

[0035] The self-bonded refractory castable for the large blast furnace tapping trough prepared in this embodiment was tested and found to have a bulk density of 3.10 g / cm³ at 110℃ for 24 hours. 3 The compressive strength at 110℃ for 24 hours is 67 MPa; the flexural strength at 1400℃ for 0.5 hours is 14.2 MPa; and the antioxidant index at 1000℃ for 5 hours is 84.2%.

[0036] Figure 1 The Gibbs free energy calculation results (obtained by computer testing) for the oxidation reactions of Al, Ti, Si, ferrous iron, and ferric iron show that aluminum and titanium have the lowest Gibbs free energy and can be preferentially oxidized and combined, providing a theoretical basis for the selection of additives.

[0037] The oxidation resistance of the self-bonded refractory castable sample for the tapping trough of a large blast furnace prepared in this embodiment was tested according to the standard GB / T 17732-2023 "Test Method for Dense Shaped Carbon-Containing Refractory Products". The test results are as follows: Figure 2 As shown, it can be seen that the silicon carbide particles are wrapped by the fused alumina particles, and the oxidation-combination of aluminum and titanium powders provides protection, resulting in weak oxidation in the central region of the sample, indicating that the sample has good oxidation resistance.

[0038] Figure 3 The cross-sectional SEM image of the self-bonded refractory castable sample of the large blast furnace tapping trough prepared for this embodiment shows that the aluminum borate whiskers formed in situ in the castable are embedded in the lamellar structure and play a pinning role, thereby improving the castable's resistance to spalling and erosion; the tightly connected grain array in the matrix enhances the bonding strength of the castable, which also improves the high-temperature thermodynamic properties of the castable.

[0039] Example 2 A self-bonding refractory castable for a large blast furnace tapping trough, the specific steps of its preparation method are as follows: 1) Aluminum powder and titanium powder are mixed at a mass ratio of 1:0.27 and added to a roller mixer and mixed for 25 minutes to obtain a premixed fine powder. 7 wt% of boric acid solution (concentration of 2 mol / L) is added to the premixed fine powder and stirred evenly. After standing in a sealed container at 25~30℃ for 20 minutes, the mixture is spray-granulated. The resulting granules are passed through a 0.5 mm round hole sieve, and the sieve-passing material is collected to obtain the spray material. The obtained spray material is mixed with amorphous zirconium oxide powder, andalusite fine powder, calcium hexaaluminate fine powder, and Suzhou clay fine powder at a mass ratio of 7:10:35:33:5 and added to a planetary mixer and mixed for 15~20 minutes to obtain a premixed matrix material. 2) Mix fused alumina particles, silicon carbide particles and aluminum silicate fibers in a mass ratio of 12.67:2.5:1, add them to a planetary mixer and mix for 5-8 minutes to obtain premixed aggregate; 3) Mix tetraethyl orthosilicate, aluminum dihydrogen phosphate and water in a mass ratio of 30:4:100, stir at 80°C for 15 minutes, seal and let stand to cool to 20~30°C to obtain the binder; 4) The premixed matrix material obtained in step 1), the premixed aggregate obtained in step 2), and the binder obtained in step 3) are mixed in a mass ratio of 7.5:16.25:1 and added to a V-type mixer. Mix for 10 minutes to obtain a self-bonding refractory castable for large blast furnace tapping troughs.

[0040] The self-bonding refractory castable for the large blast furnace tapping trough prepared in this embodiment was tested and found to have a bulk density of 3.08 g / cm³ at 110℃ for 24 hours. 3 The compressive strength at 110℃ for 24 hours is 65 MPa; the flexural strength at 1400℃ for 0.5 hours is 12.2 MPa; and the antioxidant index at 1000℃ for 5 hours is 85.7%.

[0041] Example 3 A self-bonding refractory castable for a large blast furnace tapping trough, the specific steps of its preparation method are as follows: 1) Aluminum powder and titanium powder are mixed at a mass ratio of 1:0.3 and added to a roller mixer and mixed for 40 minutes to obtain a premixed fine powder. Boric acid solution (concentration of 4mol / L) accounting for 5wt% of the premixed fine powder is added to the obtained premixed fine powder and stirred evenly. After being sealed and allowed to stand at 25~30℃ for 30 minutes, it is spray granulated. The obtained granules are passed through a 0.5mm round hole sieve, and the sieve-passing material is taken to obtain the spray material. The obtained spray material is mixed with amorphous zirconium oxide powder, andalusite fine powder, calcium hexaaluminate fine powder, and Suzhou clay fine powder at a mass ratio of 8:7:25:35:6 and added to a planetary mixer and mixed for 15~20 minutes to obtain a premixed matrix material. 2) Mix the fused alumina particles, silicon carbide particles and aluminum silicate fiber at a mass ratio of 16:5:1, add them to a planetary mixer and mix for 5-8 minutes to obtain premixed aggregate; 3) Mix tetraethyl orthosilicate, aluminum dihydrogen phosphate and water at a mass ratio of 55:3:100, stir at 85°C for 15 minutes, seal and let stand to cool to 20~30°C to obtain the binder; 4) The premixed matrix material obtained in step 1), the premixed aggregate obtained in step 2), and the binder obtained in step 3) are mixed in a mass ratio of 7:14:1 and added to a V-type mixer. After mixing for 8 minutes, a self-bonding refractory castable for large blast furnace tapping troughs is obtained.

[0042] The self-bonding refractory castable for the large blast furnace tapping trough prepared in this embodiment was tested and found to have a bulk density of 3.13 g / cm³ at 110℃ for 24 hours. 3 The compressive strength at 110℃ for 24 hours is 63 MPa; the flexural strength at 1400℃ for 0.5 hours is 15.6 MPa; and the antioxidant index at 1000℃ for 5 hours is 86.6%.

[0043] Example 4 A self-bonding refractory castable for a large blast furnace tapping trough, the specific steps of its preparation method are as follows: 1) Aluminum powder and titanium powder are mixed at a mass ratio of 1:0.175 and added to a roller mixer and mixed for 35 minutes to obtain a premixed fine powder. Boric acid solution (concentration of 3mol / L) accounting for 6wt% of the premixed fine powder is added to the obtained premixed fine powder and stirred evenly. After being sealed and allowed to stand for 20 minutes at 25~30℃, it is sprayed and granulated. The obtained granules are passed through a 0.5mm round hole sieve, and the sieve-passing material is taken to obtain the spray material. The obtained spray material is mixed with amorphous zirconium oxide powder, andalusite fine powder, calcium hexaaluminate fine powder, and Suzhou clay fine powder at a mass ratio of 5:6:30:30:8 and added to a planetary mixer and mixed for 15~20 minutes to obtain a premixed matrix material. 2) The fused alumina particles, silicon carbide particles and aluminum silicate fibers are mixed in a mass ratio of 11.14:3.14:1 and added to a planetary mixer and mixed for 5-8 minutes to obtain premixed aggregate; 3) Mix tetraethyl orthosilicate, aluminum dihydrogen phosphate and water at a mass ratio of 50:5:100, stir at 75°C for 20 minutes, seal and let stand to cool to 20~30°C to obtain the binder; 4) The premixed matrix material obtained in step 1), the premixed aggregate obtained in step 2), and the binder obtained in step 3) are mixed in a mass ratio of 6.88:13.75:1 and added to a V-type mixer. Mix for 8 minutes to obtain a self-bonding refractory castable for large blast furnace tapping troughs.

[0044] The self-bonded refractory castable for the large blast furnace tapping trough prepared in this embodiment was tested and found to have a bulk density of 3.12 g / cm³ at 110℃ for 24 hours. 3 The compressive strength at 110℃ for 24 hours is 66 MPa; the flexural strength at 1400℃ for 0.5 hours is 13.4 MPa; and the antioxidant index at 1000℃ for 5 hours is 86.3%.

[0045] Comparative Example 1 A self-bonding refractory castable for tapping troughs of large blast furnaces is prepared in a method similar to that of Example 2, except that in step 1), the mass ratio of aluminum powder to titanium powder is 1:0.05, and the mass ratio of sprayed material to amorphous zirconium oxide powder, andalusite fine powder, calcium hexaaluminate fine powder, and Suzhou clay fine powder is 7:4:35:33:5.

[0046] The self-bonded refractory castable for the tapping trough of a large blast furnace prepared in this comparative example was tested and found to have a bulk density of 3.02 g / cm³ at 110℃ for 24 hours. 3 The compressive strength at 110℃ for 24 hours is 33 MPa; the flexural strength at 1400℃ for 0.5 hours is 4.5 MPa; and the antioxidant index at 1000℃ for 5 hours is 80.3%.

[0047] As can be seen, compared with Example 2, with other conditions unchanged, increasing the proportion of metallic aluminum and titanium and reducing the content of amorphous zirconia powder leads to a decrease in the oxidation-combination degree of aluminum and titanium metals, which weakens the oxidation resistance of the material. At the same time, due to the reduction in the amount of amorphous zirconia powder added, the synergistic toughening effect of the material system is weakened. Under the influence of liquid phase viscosity and low melting point, the mechanical properties of the castable are significantly reduced.

[0048] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a self-bonding refractory castable for a large blast furnace tapping trough, characterized in that, The specific steps are as follows: 1) Add aluminum powder and titanium powder to a roller mixer and mix thoroughly to obtain a premixed fine powder. Add boric acid solution to the obtained premixed fine powder, stir evenly, and after aging treatment, spray granulation. The obtained granules are passed through a 0.5mm round hole sieve. Take the sieve-passing material to obtain spray material. Add the obtained spray material to amorphous zirconium oxide powder, andalusite fine powder, calcium hexaaluminate fine powder, and Suzhou clay fine powder in a planetary mixer and mix evenly to obtain a premixed matrix material. 2) Add fused alumina particles, silicon carbide particles and aluminum silicate fibers to a planetary mixer and mix evenly to obtain premixed aggregate; 3) Mix tetraethyl orthosilicate, aluminum dihydrogen phosphate and water to carry out a hydrolysis reaction. After the reaction is completed, seal and let stand to cool to 20~30℃ to obtain a binder; 4) Add the premixed matrix material obtained in step 1), the premixed aggregate obtained in step 2), and the binder obtained in step 3) into a V-type mixer and mix them evenly to obtain a self-bonding refractory castable for large blast furnace tapping troughs.

2. The method for preparing self-bonding refractory castable for large blast furnace tapping troughs according to claim 1, characterized in that, Step 1) The aluminum powder has a particle size of 10~25μm, the titanium powder has a particle size of 15~40μm, and the mass ratio of aluminum powder to titanium powder is 1:0.15~0.4; Step 1) The boric acid solution concentration is 2~4mol / L, and the amount of boric acid solution added is 5~8wt% of the premixed fine powder.

3. The method for preparing self-bonding refractory castable for large blast furnace tapping troughs according to claim 1, characterized in that, Step 1) The aging treatment method is as follows: seal and stand at 25~30℃ for 20~30 minutes; the amorphous zirconia powder ZrO2 content of the amorphous zirconia powder in Step 1) is ≥99wt%, and the particle size of the amorphous zirconia powder is ≤20nm; the andalusite fine powder has a particle size ≤60μm and an Fe2O3 content ≤0.3wt%; the calcium hexaaluminate fine powder has a particle size ≤50μm; the Suzhou clay fine powder has a particle size ≤75μm; the components and their mass percentages in the premixed matrix material are as follows: spray material 5~12%, amorphous zirconia powder 6~14%, andalusite fine powder 27~45%, calcium hexaaluminate fine powder 32~52%, and Suzhou clay fine powder 3~11%.

4. The preparation method of the self-bonding refractory castable for the tapping trough of a large blast furnace according to claim 1, characterized in that, Step 2) The Al2O3 content of the fused alumina particles is ≥98wt%, and it is obtained by compounding fused alumina particles of different particle sizes. The particle sizes and mass percentages are as follows: 0.1~0.5mm fused alumina particles, 8~25%, 1~3mm fused alumina particles, 25~43% 4~8mm fused alumina particles, 26~45%, 10~15mm fused alumina particles (12~23%).

5. The method for preparing self-bonding refractory castable for large blast furnace tapping troughs according to claim 1, characterized in that, Step 2) The silicon carbide particles have a SiC content ≥ 98 wt%, and are obtained by compounding silicon carbide particles with a particle size of 0.5~1 mm and silicon carbide particles with a particle size of 3~4 mm at a mass ratio of 1:1.5~4.5; Step 2) The aluminum silicate fiber has a diameter of 20~25 μm and a length of 4~8 mm; Step 2) The mass ratio of the fused alumina particles, silicon carbide particles and aluminum silicate fiber is 8~16:1.5~5:

1.

6. The method for preparing self-bonding refractory castable for large blast furnace tapping troughs according to claim 1, characterized in that, Step 3) The mass ratio of tetraethyl orthosilicate, aluminum dihydrogen phosphate and water is 30~55:2~5:100; Step 3) The hydrolysis reaction conditions are: react at 65~85℃ for 15~20 minutes.

7. The method for preparing self-bonding refractory castable for large blast furnace tapping troughs according to claim 1, characterized in that, Step 4) The mass ratio of the premixed matrix, premixed aggregate and binder is 6~9:13~17.5:

1.

8. A self-bonding refractory castable for a large blast furnace tapping trough prepared by the method of preparing the self-bonding refractory castable for a large blast furnace tapping trough according to any one of claims 1-7.

9. The application of the self-bonding refractory castable for large blast furnace tapping troughs as described in claim 8 as a refractory material in the field of blast furnace exhaust systems.

10. A refractory material for a large blast furnace tapping trough, prepared from a self-bonding refractory castable according to claim 8, characterized in that, It is obtained by first curing the self-bonding refractory castable for the tapping trough of a large blast furnace as described in claim 8 at 25~30℃ for 24~48 hours, then heating it to 100~150℃ for 48~60 hours, then heating it to 1000~1200℃ for 24~48 hours, with the heating rate ≤5℃ / min throughout the process, and finally cooling it to room temperature.

Images