A converter nozzle brick and a method for manufacturing the same

Abstract

The application discloses a converter nozzle brick and a preparation method thereof, and belongs to the field of refractory materials. The converter nozzle brick is composed of the following components and in the following weight percentage: modified mullite 55-65%, quartz sand 10-15%, 30-35% of co-milling powder, and the total percentage is 100%; and 3.5-4.5% of additional phenolic resin binder. The modified mullite and the quartz sand are introduced as main raw materials, the modified mullite is used to generate a silicon carbide micro-network structure on the surface of the electric smelting mullite at 1600-1700 DEG C with high-activity nano-graphite fine powder, the thermal conductivity and the erosion resistance of the slide plate brick are improved without destroying the low creep property of the electric smelting mullite. Meanwhile, the electric smelting mullite is controlled to be in a needle-like whisker structure, so that the converter nozzle brick has good corrosion resistance, thermal shock resistance and high-temperature resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of refractory materials, more particularly, relates to a converter nozzle brick and a preparation method thereof. BACKGROUND

[0002] Converter steelmaking has become the mainstream of steelmaking in China due to its high efficiency, short smelting cycle and low cost of steel production. As a technology to improve the quality of molten steel and reduce the amount of slag, the converter sliding slag dam also appears. The converter nozzle brick is the core part of the sliding nozzle device used in the sliding slag dam of the converter. During use, it not only withstands the high pressure washing of molten steel, but also faces the situation of alternating cold and hot. At this time, the nozzle brick needs to have good resistance to washing and thermal shock resistance. At present, the domestic converter nozzle brick mainly uses high alumina bauxite and white corundum as the main raw material. This type of converter nozzle brick has high resistance to washing. However, with the acceleration of steelmaking technology and rhythm, the life requirement of converter nozzle brick is further improved in major steel plants. Ordinary high alumina bauxite and white corundum nozzle brick cannot meet the requirements. The present application adds modified mullite and quartz sand to improve the resistance to washing and bending strength of the converter nozzle brick, and provides a high-life converter nozzle brick.

[0003] After searching, patent CN113773088A provides a preparation method of mullite combined with SiC abrasive, the specific preparation steps are as follows: adding silicon carbide powder into ethanol aqueous solution, ultrasonic stirring for 1-2h; preparing mullite sol, adding SiC powder ethanol aqueous solution, ultrasonic stirring for 1-2h, drying to obtain mullite coated silicon carbide particles; then adding PVA and mixing uniformly, after sealing and standing, granulating, drying to obtain SiC particles with uniform size; the silicon carbide particles are heat treated at 1200-1500℃ for 2-3h to obtain mullite combined with SiC abrasive with re-sized particles. Again, patent CN109761612A discloses a low-temperature high-performance silicon carbide film and a preparation method thereof, which uses the oxidation of silicon carbide powder in a high-temperature environment to generate silicon dioxide on the surface of the particles. The silicon dioxide reacts with the nano-sized aluminum sol wrapped on the surface of the silicon carbide particles to establish a mullite network structure. Again, patent CN108249900A discloses a high-performance Al2O3-SiC-C-based castable additive and a preparation method thereof. The additive contains, by weight, 5-9 parts of iron aluminate spinel, 1-3 parts of carbon black, 1-3 parts of silicon dioxide powder, 3-6 parts of aluminum oxide powder, 2-4 parts of zirconium dioxide, 1-3 parts of silicon nitride iron, and 1-2 parts of magnesia. In the present application, the in-situ formed SiC and mullite can form a network structure to improve the bonding strength and strengthen the matrix; the addition of nitride and in-situ formation improves the corrosion resistance and impact resistance.

[0004] In the above patents, a network structure containing SiC and mullite is formed, but the mullite is coated on the surface of the silicon carbide particles or forms a network structure with the silicon carbide, which cannot guarantee the low creep property of the mullite and affects the thermal shock resistance of the slide plate brick. SUMMARY

[0005] 1. PROBLEMS TO BE SOLVED

[0006] In view of the problem that the low creep property of mullite cannot be guaranteed in the existing slide plate brick containing SiC and mullite, which affects the thermal shock resistance of the slide plate brick, the present application provides a converter nozzle brick and a preparation method thereof, which utilizes in-situ generated silicon carbide to coat the surface of mullite, retains the low creep property of mullite, and improves the thermal shock resistance of the slide plate brick.

[0007] 2. TECHNICAL SCHEME

[0008] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0009] The present application aims to provide a converter nozzle brick, which improves the thermal conductivity and erosion resistance of the nozzle brick by adding modified mullite and quartz sand while maintaining the original low creep characteristics of mullite, so that the nozzle brick has good erosion resistance and thermal shock resistance, and the service life of the nozzle brick is improved.

[0010] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0011] A converter nozzle brick, the composition and weight percentage of which are as follows:

[0012] 65%-70% of granular material and 30%-35% of co-milled powder, with a total percentage of 100%, plus 3.5%-4.5% of phenolic resin binder. The granular material includes 55%-65% of modified mullite particles and 10%-15% of quartz sand; the co-milled powder is uniformly mixed from 5%-10% of modified mullite fine powder, 1%-5% of alpha-Al2O3 micro powder, 5%-10% of tabular corundum fine powder, 1%-3% of metallic silicon powder, and 5%-8% of metallic aluminum powder.

[0013] The modified mullite is prepared by stirring uniformly and then firing at 1700 DEG C, using mullite whiskers and nano-level graphite fine powder as the main raw materials.

[0014] The preparation method of the modified mullite includes the following steps:

[0015] Step one: weigh 80%-90% of mullite and 10%-20% of nano graphite fine powder, stir uniformly in a stirrer, and obtain a uniform mixture.

[0016] Step two: the above obtained homogeneous mixture is kept at 1600-1700 DEG C for 10-12 hours under a protective atmosphere to obtain modified mullite.

[0017] Step three: the cooled modified mullite is sieved to obtain modified mullite particles and fine powder of different particle sizes.

[0018] Further, the mullite is mullite whisker, the electrically fused mullite is the aggregate, and the mullite whisker network is generated by the reaction of the electrically fused mullite, the alumina and the silica under the action of the auxiliary agent.

[0019] The auxiliary agent is selected from one or more of V2O5, AlF3 and MoO3 to form the mullite whisker with more controllable morphology.

[0020] Further, the particle size of the modified mullite particles is (5-3, 3-1, 1-0) mm, and the weight percentage of each particle size is as follows: the weight percentage of the modified mullite particles with a particle size of 5-3 mm is 10-15%, the weight percentage of the modified mullite particles with a particle size of 3-1 mm is 35-20%, and the weight percentage of the modified mullite particles with a particle size of 1-0 mm is 30-20%; the chemical components and contents of the modified mullite are as follows: the content of Al2O3 is 65-70%, the content of SiO2 is 18-22%, and the content of SiC is ≤9%.

[0021] Notably, different particle sizes of the electrically fused mullite raw material are selected for modification, and the obtained SiC-wrapped modified mullite has different particle sizes, and the packing density is increased by reasonable particle size grading adjustment.

[0022] Further, the quartz sand is embedded in the SiC network, and the quartz sand has a high melting point, thereby further reducing the corrosion of the molten steel on the electrically fused mullite.

[0023] Preferably, the particle size of the quartz sand is (1-0.5, 0.5-0) mm, and the weight percentage of each particle size is as follows: the weight percentage of the quartz sand with a particle size of 1-0.5 mm is 5-10%, and the weight percentage of the quartz sand with a particle size of 0.5-0 mm is 3-6%; the chemical components and contents of the quartz sand are as follows: the content of SiO2 is ≥99.5%, and the content of Fe2O3 is ≤0.001%.

[0024] Preferably, the particle size of the α-Al2O3 micro powder is 0-2 μm; in the α-Al2O3 micro powder, the content of Al2O3 is ≥99.0%, the content of SiO2 is ≤0.1%, the content of Fe2O3 is ≤0.08%, and the content of Na2O+K2O is ≤0.3%.

[0025] Preferably, the plate-like corundum fine particle size is 0-2 μm; the plate-like corundum fine particle size: Al2O3 content ≥ 99.0%, SiO2 content ≤ 0.1%, Fe2O3 content ≤ 0.08%, Na2O+K2O content ≤ 0.3%.

[0026] Preferably, the metal silicon powder: Si content ≥ 99.0%, Fe2O3 content ≤ 0.2%, SiO2 content ≤ 0.1%, free silicon content ≤ 0.4%.

[0027] Preferably, the metal aluminum powder: Al content ≥ 99.0%, Fe content ≤ 0.2%, Si content ≤ 0.2%, Cu content ≤ 0.1%.

[0028] Another object of the present application is to provide a preparation method of a converter nozzle brick, comprising the following steps:

[0029] Step one, co-milling powder preparation: uniformly mixing modified mullite fine powder, α-Al2O3 micro powder, plate-like corundum fine powder, metal silicon powder and metal aluminum powder according to weight percentage to obtain co-milling powder;

[0030] Step two, granular material batching: uniformly mixing modified mullite granules with particle size of 5-3 mm, modified mullite granules with particle size of 3-1 mm, modified mullite granules with particle size of 1-0 mm, quartz sand with particle size of 1-0.5 mm and quartz sand with particle size of 0.5-0 mm according to weight percentage to obtain granular batching;

[0031] Step three, mixing: dry mixing the granular aggregate with a wet mill for 2-3 minutes, then adding phenolic resin binder at a uniform speed, wet mixing for 8-10 minutes, then adding co-milling powder, and rolling and pressing for 35-40 minutes to obtain mixed mud;

[0032] Step four, forming: pressing and forming the mixed mud on a 630t electric screw brick press to obtain green bricks;

[0033] Step five, drying: drying the green bricks in a drying kiln, the initial temperature for entering the kiln is 20℃, drying at this temperature for more than 2 hours; increasing the temperature to 60℃, drying at this temperature for more than 4 hours; increasing the temperature to 150-180℃, drying for more than 8 hours; increasing the temperature to 220℃, drying for more than 12 hours;

[0034] Step six, firing: firing the dried brick blank, the highest firing temperature is 1200℃, and the holding time at this temperature is 12 hours;

[0035] Step seven, casing: buckling the steel shell on the converter nozzle coated with fire clay, and placing it in the tooling in an inverted manner, and using the inverted pressing method to make it conform to the assembly size;

[0036] Step eight, drying: drying in a drying kiln, drying at 160 DEG C for more than 8 hours to dry and harden the mortar;

[0037] Step nine, after inspection and packaging to obtain the finished product.

[0038] 3. Beneficial effects

[0039] Compared with the prior art, the beneficial effects of the present application are:

[0040] (1) The modified mullite is introduced into the converter nozzle brick in the present application, the silicon carbide network structure is generated in situ on the surface of the electrically fused mullite, the thermal conductivity and the erosion resistance are improved without damaging the low creep property of the electrically fused mullite, thereby effectively reducing the erosion of the converter nozzle brick and improving the service life of the converter nozzle brick.

[0041] (2) The modified mullite in the converter nozzle brick of the present application is needle-like mullite whisker, by adjusting the morphology of the mullite whisker, the mullite whisker is distributed in the slide plate brick, and the converter nozzle brick prepared has good thermal shock resistance, and cracking of the converter nozzle brick during multiple uses is avoided, thereby reducing the service life. BRIEF DESCRIPTION OF DRAWINGS

[0042] The technical solutions of the present application will be further described in detail below in combination with the drawings and examples, but it should be understood that these drawings are designed only for illustrative purposes, and therefore do not limit the scope of the present application. In addition, unless specifically indicated, these drawings are only intended to conceptually illustrate the structural configuration described herein, and are not necessarily drawn to scale.

[0043] Figure 1 The photo of the converter lower nozzle of Comparative Example 1 after 15 heats;

[0044] Figure 2 The photo of the converter lower nozzle of the present application after 18 heats. DETAILED DESCRIPTION

[0045] The following detailed description of exemplary embodiments of the present application refers to the accompanying drawings that form a part of this description, in which are shown, by way of example, exemplary embodiments in which the present application can be practiced. Although these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the present application, it is understood that other embodiments can be realized and that various changes can be made without departing from the spirit and scope of the present application. The following detailed description of embodiments of the present application is not intended to limit the scope of the claimed application, but is merely intended to provide an example illustration of the features and characteristics of the present application, to set forth the best mode contemplated for carrying out the present application, and to enable one skilled in the art to practice the present application. The scope of the present application is defined solely by the appended claims.

[0046] In the present application, the materials are commercially available, i.e. commercially available products, unless otherwise specified.

[0047] The modified mullite is prepared by using mullite and nano-graphite fine powder as main raw materials, stirring uniformly and then sintering at 1600-1700 DEG C.

[0048] The preparation method of the modified mullite comprises the following steps:

[0049] Step one: stirring uniformly mullite with mass fraction of 80-90% and nano-graphite fine powder with mass fraction of 10-20% to obtain a uniform mixture.

[0050] Step two: obtaining the modified mullite by sintering the uniform mixture obtained in step one at 1600-1700 DEG C for 10-12 hours under N2 environment.

[0051] Step three: screening the cooled modified mullite to obtain modified mullite particles and fine powder with different particle sizes.

[0052] In the prepared modified mullite, the nano-graphite fine powder with high activity generates silicon carbide micro-particles on the surface of the electro-fused mullite at high temperature to wrap the electro-fused mullite, so that the electro-fused mullite is covered with a net-like structure of silicon carbide film, the silicon carbide film is a three-dimensional network structure composed of aromatic ring network and silicon atoms, and the thermal conductivity and the erosion resistance are improved without damaging the original low creep property of the electro-fused mullite, thereby effectively reducing the erosion of the converter nozzle brick and prolonging the service life of the converter nozzle brick.

[0053] The needle-like mullite whisker is selected for modification, the mullite whisker is prepared by using electro-fused mullite microspheres as aggregate, and the mullite whisker network is generated by reacting with alumina and silicon dioxide under the action of an additive at a reaction condition of 1200-1500 DEG C for 4 hours.

[0054] The components and contents of the electro-fused mullite microspheres raw material are 3Al2O3·2SiO2 content ≥ 99.0%, Fe2O3 ≤ 0.08%, and Na2O ≤ 0.02%.

[0055] When MoO3 is selected as an additive, the addition amount is 20wt% of the fused mullite microspheres. MoO3 reduces the viscosity of the silicon-rich liquid phase and increases the solubility of Al2O3, thereby promoting the nucleation of fused mullite. The octahedral structure of [MoO6] existing in MoO3 has a templating effect, which can induce the growth of mullite whiskers. The mullite whiskers have higher crystallinity, more regular and uniform needle-like structure, better crystal structure, and hard organization. Even if broken, the broken particles are small needle-like cylinders or sharp prismatic shapes. This particle morphology is beneficial to the manufacture of refractory products and easy to form maximum bulk density to make the product structure dense.

[0056] The mullite whiskers can improve the bulk density, but are easy to break, which affects the strength of the slide plate brick. Therefore, V2O5 and AlF3 are selected as additives to prepare mullite whiskers. Silicon sol is also added as a binder in the reaction. The addition amount of V2O5 is 0.5wt%-1.5wt%, the addition amount of AlF3 is 2wt%-6wt%, and the addition amount of silicon sol is 10wt%.

[0057] The mullite whiskers exhibit different morphologies with different addition amounts of AlF3. When the content of AlF3 is 2wt%, part of the mullite whiskers appear in the pores, and the whiskers are easy to break. When the content of AlF3 increases to 4wt%, the growth of the whiskers becomes more obvious, and the breaking amount decreases. Part of the morphology changes from short rods to rod-like whiskers. When the content of AlF3·3H2O further increases to 6wt%, the mullite whiskers grow longitudinally, become thinner and longer, and the breaking amount significantly decreases. There may be two reasons for this phenomenon: (1) the toughness of the aggregate is enhanced by the growth of a large number of whiskers on the surface of the aggregate, and (2) the mullite whiskers form an interlaced network, which greatly disperses the stress applied to the surface of the aggregate, so the whiskers are not easy to break.

[0058] In the process of generating mullite whiskers, part of the SiO2 in the silicon sol acts as a filler to fill the gaps in the whiskers, improving the structural strength. Part of the SiO2 acts as a Si source to form a cross-linked SiC network with graphite, further ensuring the low creep property of fused mullite.

[0059] Example 1

[0060] A converter nozzle brick, 65%-70% of the granular material and 30%-35% of the co-milled powder, the total percentage is 100%, plus 3.5%-4.5% of phenolic resin binder. The granular material includes 55%-65% of modified mullite particles and 10%-15% of quartz sand; the co-milled powder is prepared by uniformly mixing 5%-10% of modified mullite fine powder, 1%-5% of α-Al2O3 micro powder, 5%-10% of tabular corundum fine powder, 1%-3% of metallic silicon powder, and 5%-8% of metallic aluminum powder.

[0061] The particle size of the modified mullite is (5-3, 3-1, 1-0) mm, and the weight percentage of each particle size is: 10% of modified mullite particles with a particle size of 5-3 mm, 30% of modified mullite particles with a particle size of 3-1 mm, and 20% of modified mullite particles with a particle size of 1-0 mm; the chemical composition and content of the modified mullite are: the content of Al2O3 is 69.8%, the content of SiO2 is 21.2%, and the content of SiC is 9%.

[0062] The particle size of the quartz sand is (1-0.5, 0.5-0) mm, and the weight percentage of each particle size is: 7% of quartz sand with a particle size of 1-0.5 mm and 3% of quartz sand with a particle size of 0.5-0 mm; the chemical composition and content of the quartz sand are: the content of SiO2 is ≥99.5%, and the content of Fe2O3 is ≤0.001%.

[0063] The particle size of the α-Al2O3 micro powder is 0-2 μm; in the α-Al2O3 micro powder: the content of Al2O3 is ≥99.0%, the content of SiO2 is ≤0.1%, the content of Fe2O3 is ≤0.08%, and the content of Na2O+K2O is ≤0.3%.

[0064] The particle size of the plate-shaped corundum subdivision is 0-2 μm; in the plate-shaped corundum subdivision: the content of Al2O3 is ≥99.0%, the content of SiO2 is ≤0.1%, the content of Fe2O3 is ≤0.08%, and the content of Na2O+K2O is ≤0.3%.

[0065] In the metallic silicon powder: the content of Si is ≥99.0%, the content of Fe2O3 is ≤0.2%, the content of SiO2 is ≤0.1%, and the content of free silicon is ≤0.4%.

[0066] In the metallic aluminum powder: the content of Al is ≥99.0%, the content of Fe is ≤0.2%, the content of Si is ≤0.2%, and the content of Cu is ≤0.1%.

[0067] The preparation method of the modified mullite is: the mullite whiskers are prepared by using fused mullite microspheres as aggregates, reacting with alumina and silicon dioxide under the action of MoO3 to form a mullite whisker network, and the reaction conditions are 1300℃ for 4h. The addition amount of MoO3 is 20wt%. The above-mentioned mullite whiskers and nano-level graphite powder are stirred uniformly, and then modified mullite is prepared by firing at 1650℃ in N2 atmosphere.

[0068] In the modified mullite, the nano-graphite powder with high activity generates silicon carbide micro-particles on the surface of the fused mullite at high temperature, which wraps the fused mullite, so that the surface of the fused mullite is covered with a network structure of silicon carbide film.

[0069] Compared with the structure of full wrapping of SiC, the net structure adopted by the application can not only effectively prevent the molten steel from wetting the fused mullite particles to improve the corrosion resistance, but also can relieve the thermal expansion of the fused mullite to a certain extent. The reason is that the slide plate brick of the application contains a large amount of Al2O3. When there is excess Al2O3, the process of forming fused mullite by combining Al2O3 and high SiO2 can occur during high-temperature use, that is, secondary fused mullitization. The secondary fused mullitization process is accompanied by a large volume expansion of 7-8%. By forming mullite whiskers, gaps exist between the whiskers, which can effectively relieve the volume expansion and improve the service life of the slide plate brick.

[0070] The preparation method of the converter nozzle brick described above comprises the following steps:

[0071] Step one, preparation of co-ground powder: uniformly mix modified mullite fine powder, α-Al2O3 micro powder, tabular corundum fine powder, metal silicon powder and metal aluminum powder according to the weight percentage to obtain co-ground powder;

[0072] Step two, granular material batching: uniformly mix modified mullite particles with a particle size of 5-3 mm, modified mullite particles with a particle size of 3-1 mm, modified mullite particles with a particle size of 1-0 mm, quartz sand with a particle size of 1-0.5 mm and quartz sand with a particle size of 0.5-0 mm according to the weight percentage to obtain granular batching;

[0073] Step three, mixing: dry mix the granular aggregate with a wet mill for 2-3 minutes, then add the phenolic resin binder at a uniform speed, wet mix for 8-10 minutes, then add the co-ground powder, and roll and press for 35-40 minutes to obtain mixed mud;

[0074] Step four, forming: press and form the mixed mud into green bricks on a 630t electric screw brick press;

[0075] Step five, drying: dry the green bricks in a drying kiln, the initial temperature for entering the kiln is 20℃, and the drying is performed at this temperature for more than 2 hours; the temperature is increased to 60℃, and the drying is performed at this temperature for more than 4 hours; the temperature is increased to 150-180℃, and the drying is performed at this temperature for more than 8 hours; the temperature is increased to 220℃, and the drying is performed at this temperature for more than 12 hours

[0076] Step six, firing: fire the dried brick blank, and the highest firing temperature is 1200℃, and the holding time at this temperature is 12 hours;

[0077] Step seven, casing: buckle the steel shell on the converter nozzle coated with fire clay, and place it in the tooling in an inverted manner, and use the inverted pressing method to make it meet the assembly size;

[0078] Step eight, drying: dry in a drying kiln, and dry at 160℃ for more than 8 hours to harden the fire clay.

[0079] Step nine, after inspection, the finished product is ready for packaging.

[0080] Example 2

[0081] The converter nozzle brick of the example is prepared according to the formula shown in Table 1, and the preparation method is the same as that of Example 1.

[0082] The mullite whisker is prepared by taking electrically fused mullite microspheres as aggregate, V2O5 and AlF3 as additives, and silica sol as binder. The addition amount of V2O5 is 1wt%, the addition amount of AlF3 is 4wt%, and the addition amount of silica sol is 10wt%. The reaction condition is 1100-1200℃ for 4h.

[0083] The modified mullite is prepared by stirring the above mullite whisker and nano-level graphite powder uniformly and then firing at 1650℃ in N2 atmosphere.

[0084] Example 3

[0085] The converter nozzle brick of the example is prepared according to the formula shown in Table 1, and the preparation method is the same as that of Example 1.

[0086] The mullite whisker is prepared by taking electrically fused mullite microspheres as aggregate, V2O5 and AlF3 as additives, and silica sol as binder. The addition amount of V2O5 is 1wt%, the addition amount of AlF3 is 6wt%, and the addition amount of silica sol is 10wt%. The reaction condition is 1100-1200℃ for 4h.

[0087] The modified mullite is prepared by stirring the above mullite whisker and nano-level graphite powder uniformly and then firing at 1650℃ in N2 atmosphere.

[0088] Example 4

[0089] The converter nozzle brick of the example is prepared according to the formula shown in Table 1, and the preparation method is the same as that of Example 1.

[0090] The preparation method of the modified mullite is as follows: the mullite whisker is prepared by taking electrically fused mullite microspheres as aggregate, and reacting with alumina and silicon dioxide under the action of MoO3 to form a mullite whisker network. The reaction condition is 1300℃ for 4h. The addition amount of MoO3 is 20wt%. The modified mullite is prepared by stirring the above mullite whisker and nano-level graphite powder uniformly and then firing at 1650℃ in N2 atmosphere.

[0091] Comparative Example 1

[0092] The converter nozzle brick of the comparative example 1 and the example 1 has the same component proportion, and the difference is that the existing commercial electric melting mullite is used to replace the modified mullite.

[0093] Table 1: The particle type and percentage of the ingredients used in the examples of the present application

[0094]

[0095] The converter nozzle brick is prepared according to the above examples.

[0096] Table 4: The physical and chemical properties and average service life of the converter nozzle bricks obtained in the examples 1-4 and the existing converter nozzle bricks.

[0097] Table 2: The physical and chemical properties and average service life of the converter nozzle bricks of the examples and the comparative example

[0098]

[0099] It can be seen from Table 2 that the converter nozzle bricks of the present application are used in the large converter, and the erosion and crack analysis of the converter nozzle bricks and the comparative example is carried out after the test is completed. The service life is 17-21 times / set. Through the comparison and measurement analysis of the existing products, the volume density of the converter nozzle brick of the present application is obviously increased, and the average erosion rate is improved to a certain extent compared with the erosion rate of the existing converter nozzle brick. After the use of the converter nozzle brick is completed, there is basically no crack, and compared with the ordinary converter nozzle brick, the crack after use is more, and even there is obvious improvement in the case of through crack. Therefore, the converter nozzle brick of the present application has excellent erosion resistance, thermal shock resistance and high temperature resistance.

Claims

1. A converter nozzle brick, characterized in that, The composition and weight percentage of the converter nozzle brick are: 65%-70% of granular material: including 10%-15% of quartz sand, 55%-65% of modified mullite granular material, the modified mullite granular material including mullite whisker and silicon carbide network structure wrapped on the surface of the mullite whisker; 30%-35% of co-milling powder, the total percentage of the granular material and the co-milling powder being 100%; 3.5%-4.5% of additional phenolic resin binder; The preparation method of the modified mullite includes the following steps: uniformly stirring the mullite whisker and nano-graphite fine powder, and then firing at 1600-1700 ℃ in a protective atmosphere to obtain the modified mullite.

2. The converter nozzle brick of claim 1, wherein The co-milling powder is prepared by uniformly mixing 5%-10% of modified mullite fine powder, 1%-5% of α-Al2O3 micro powder, 5%-10% of tabular corundum fine powder, 1%-3% of metal silicon powder, and 5%-8% of metal aluminum powder.

3. The converter nozzle brick of claim 2, wherein The mass fraction of the mullite whisker added is 80%-90%, the mass fraction of the nano-graphite fine powder added is 10%-20%, and the firing condition is 1600-1700 ℃ for 10-12 hours to obtain the modified mullite granular material and the modified mullite fine powder.

4. The converter nozzle brick of claim 1, wherein The weight percentage of each particle size of the modified mullite granular material is: 10%-15% of modified mullite granular material with a particle size of 5-3 mm, 35%-20% of modified mullite granular material with a particle size of 3-1 mm, and 30%-20% of modified mullite granular material with a particle size of 1-0 mm.

5. A method of making a converter nozzle brick according to any one of claims 1 to 4, characterised in that, The method includes the following steps: batching, mixing, molding, drying, firing, casing, drying, and packaging after inspection to obtain the finished product.

6. The production method according to claim 5, characterized by, In the firing step: the dried brick blank is fired, and the highest firing temperature is 1200 ℃, and the holding time at this temperature is 12 hours.

7. The production method according to claim 6, wherein In the drying step: the green brick is dried in a drying kiln, the initial temperature of the kiln is 20 ℃, and the drying time at this temperature is more than 2 hours; the temperature is increased to 60 ℃, and the drying time at this temperature is more than 4 hours; the temperature is increased to 150-180 ℃, and the drying time is more than 8 hours; the temperature is increased to 220 ℃, and the drying time is more than 12 hours.

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