An antioxidant blast furnace trough castable and a preparation method thereof

Abstract

This invention belongs to the field of refractory materials technology, specifically relating to an antioxidant blast furnace tapping trough castable and its preparation method. The blast furnace tapping trough castable comprises the following raw materials in parts by weight: 55-75 parts corundum, 15-25 parts silicon carbide, 15-25 parts ferrosilicon silicon nitride, 5-10 parts carbonaceous material, 4-6 parts nano-Al2O3, 0.1-0.5 parts dispersant, 20-40 parts binder, and 5-10 parts explosion-proof fiber. The binder comprises modified phenolic resin, p-aminophenyl POSS, and an alcohol solvent. The modified phenolic resin is obtained by the condensation polymerization of formaldehyde, hydroxyphenyl borate ester, and phenol. The binder of the blast furnace tapping trough castable includes modified phenolic resin, p-aminophenyl POSS, and alcohol solvent. The modified phenolic resin is prepared by reacting formaldehyde, hydroxyphenyl borate ester, and phenol. The binder generates a dense, antioxidant Si-B-C ceramic phase in situ during high-temperature baking and use, which improves the strength, oxidation resistance, and slag erosion resistance of the castable.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to an antioxidant blast furnace tapping trough castable and its preparation method. Background Technology

[0002] The blast furnace tapping trough is the main channel for high-temperature molten iron and slag. During use, the trough not only endures the intense scouring and erosion of the flowing high-temperature molten iron and slag, but also withstands the rapid temperature changes during intermittent tapping and the frequent alternation of rapid heating and cooling. Therefore, the trough material must have strong resistance to scouring by molten iron and slag; good thermal shock resistance; minimal reheating volume change; strong oxidation resistance; convenient construction; no adhesion of slag and iron, facilitating repair and dismantling; a uniform, highly dense structure with high strength; and no generation of harmful gases, thus contributing to environmental protection.

[0003] There are many ways to classify blast furnace tapping trough materials: by material, they can be divided into corundum, mullite, spinel, and composite types; by binder, they can be divided into low-cement bonded, sol-gel bonded, carbon material bonded, silane bonded, and phenolic resin bonded types; and by construction method, they can be divided into ramming mixes, castable mixes, and shotcrete mixes. Currently, the main type of blast furnace tapping trough material used is the traditional Al2O3-SiC-C material. Al2O3 is an oxide with strong resistance to Na2CO3, K2CO3, and molten iron erosion, but pure Al2O3 has a high coefficient of thermal expansion and poor resistance to spalling; the matrix is ​​easily penetrated and eroded by slag. Carbon (such as coke, graphite, and asphalt) has poor wettability with molten iron and slag, effectively improving its resistance to penetration. SiC has high thermal conductivity, a low coefficient of thermal expansion, good toughness, and a glaze layer formed by surface oxidation, further improving its resistance to spalling and erosion. For example, patent CN100519483C discloses an iron tapping trough and its preparation method. CN101693625B discloses a ramming material for blast furnace iron tapping troughs. The above are castables with Al2O3-SiC-C as the core system, which combine the excellent properties of traditional Al2O3-SiC-C castables in terms of erosion resistance, thermal shock resistance and slag erosion resistance.

[0004] However, with the development of larger and more efficient blast furnaces, the iron output has increased significantly, and the flow rate and impact force of molten iron have also increased dramatically. The operating conditions of the tapping trough, such as high-temperature erosion, slag penetration, and temperature fluctuations, have become more severe, and the inherent defects of traditional Al2O3-SiC-C iron trough materials have gradually become apparent: the C and SiC they contain are easily oxidized at high temperatures. The pores and cracks produced by oxidation directly damage the material's density, making it unable to effectively prevent slag penetration, which in turn leads to spalling and slag erosion problems, resulting in a shortened service life. To solve the problem of easy oxidation of C and SiC at high temperatures, researchers in this field have conducted extensive research and have grown a continuous network of SiAlON oxygen barrier layer by in-situ reaction of appropriate amounts of silicon nitride with alumina in the raw material. For example, patent CN1232470C discloses a non-baking ramming mix containing silicon nitride, which is composed of aluminum silicate material, silicon carbide, carbon material, silicon nitride, binder, and additives. The additives are Si powder and / or Al powder. The characteristics are: aluminum silicate material is 43-80%, silicon carbide is 7-25%, carbon material is 2-10%, silicon nitride is 5-15%, Si powder is 0-4%, Al powder is 0-3%, and liquid phenolic resin is added as a binder to the above mixture. The use of phenolic resin as a binder can cause microcracks to easily penetrate when it cracks and shrinks at high temperature, making it difficult to form continuous new silane phases, and the oxygen barrier layer is easily damaged and loses its effectiveness. Patent CN104761266B discloses a fast-baking explosion-proof iron trench castable and its application method. The dry material comprises the following components by weight: 55-70% brown corundum, 8-14% silicon carbide, 4-8% silicon nitride iron, 5-8% alumina micro powder, 1-3% silicon micro powder, 2-3% composite carbon material, and 2-3% antioxidant; the additives are an explosion-proof agent and sodium hexametaphosphate, accounting for 0.1-0.15% of the dry material by weight; the binder is silica sol, accounting for 8-15% of the dry material by weight, wherein the silica sol contains 15-25 wt% SiO2, has a pH between 7 and 9, and the SiO2 particle size is 10-50 nm. The above describes how doping silicon nitride iron improves the high-temperature oxidation resistance of iron trough materials. However, this approach still has insurmountable problems. When using silica sol as a binder, a highly surface-energy and highly active amorphous glass phase is generated at medium and high temperatures, which is easily wetted and eroded by molten slag. This approach still does not fundamentally solve the problem of molten slag erosion of iron trough materials.

[0005] Therefore, it is necessary to further improve the blast furnace taphole castable to fundamentally solve the problem of poor high-temperature erosion resistance of the castable, so that the castable has excellent oxidation resistance, strength and slag penetration resistance, and ensures the long-term stable and efficient operation of the blast furnace. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an antioxidant blast furnace tapping trough castable and its preparation method. The binder of the blast furnace tapping trough castable includes modified phenolic resin, p-aminophenyl POSS, and an alcohol solvent. The modified phenolic resin is prepared by reacting formaldehyde, hydroxyphenyl borate ester, and phenol. During high-temperature baking and use, the binder generates a dense antioxidant Si-BC ceramic phase in situ, thereby improving the strength, antioxidant properties, and slag erosion resistance of the castable.

[0007] To achieve the above objectives, the following technical solution is adopted:

[0008] An antioxidant blast furnace tapping trough castable comprises the following raw materials in parts by weight: 55-75 parts corundum, 15-25 parts silicon carbide, 15-25 parts silicon nitride ferrosilicon, 5-10 parts carbonaceous material, 4-6 parts nano-Al2O3, 0.1-0.5 parts dispersant, 20-40 parts binder, and 5-10 parts explosion-proof fiber. The binder comprises modified phenolic resin, p-aminophenyl POSS, and alcohol solvent. The modified phenolic resin is obtained by polycondensation of formaldehyde, hydroxyphenyl borate ester, and phenol.

[0009] Hydroxyphenyl borate esters replace part of the phenol in the polycondensation reaction of modified phenolic resins, introducing boron components without significantly reducing the bonding performance; the boron element reacts synergistically with the silicon element in p-aminophenyl POSS at high temperature to generate a dense Si-BC ceramic phase in situ, which improves the mechanical strength, oxidation resistance and slag erosion resistance of the iron trough castable.

[0010] The modified phenolic resin and p-aminophenyl POSS have a mass ratio of 6-8:2-4, preferably 7-8:2-3. The modified phenolic resin is prepared by polycondensation of formaldehyde, hydroxyphenyl borate ester, and phenol in a molar ratio of 1.5-2:0.15-0.25:0.75-0.85.

[0011] The alcohol solvent is selected from at least one of ethanol, ethylene glycol, isopropanol, and glycerol.

[0012] The binder has a solid content of 40-60 wt%.

[0013] The hydroxyphenylboronic acid ester is selected from at least one of 4-hydroxyphenylboronic acid pinacol ester, 3-hydroxyphenylboronic acid pinacol ester, and 2-(4,4,5,5-tetramethyl-1,3,2-diaxopentabolane-2-yl)phenol.

[0014] The formaldehyde is in the form of a 35-40 wt% formaldehyde aqueous solution.

[0015] The binder is prepared by a method comprising the following steps:

[0016] 1) Formaldehyde, hydroxyphenyl borate, phenol, and catalyst are mixed, heated to react, and dehydrated to obtain modified phenolic resin.

[0017] 2) Mix the modified phenolic resin, p-aminophenyl POSS, and alcohol solvent to obtain the binder.

[0018] The catalyst is selected from at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide. The amount of the catalyst used is 0.4-0.8 wt% of the sum of the masses of formaldehyde, hydroxyphenyl borate, and phenol. The heating reaction is carried out at 65-80℃ for 3-6 hours. The dehydration is carried out by drying at 70-85℃ under a vacuum of 0.05-0.08 MPa for 1-3 hours.

[0019] The dispersant is selected from at least one of stearic acid, oleic acid, zinc stearate, and magnesium stearate.

[0020] The carbonaceous material is selected from at least one of graphite and amorphous carbon.

[0021] The carbonaceous material has an average particle size of 0.1-0.3 mm.

[0022] The corundum is selected from at least one of tabular corundum, fused white corundum, sub-white corundum, brown corundum, and dense corundum.

[0023] The corundum has a particle size composition of 1-1.5mm and 1.5-5mm, and the mass ratio of corundum with a particle size of 1-1.5mm and 1.5-5mm is 1:3-5.

[0024] The silicon carbide has a particle size composition of 1-3 mm and 0.05-0.15 mm, and the mass ratio of silicon carbide with particle sizes of 1-3 mm and 0.05-0.15 mm is 1:2-4. The silicon nitride iron contains 45-50% Si, 14-17% Fe, and 25-35% N.

[0025] The silicon nitride has a particle size distribution of 1-3 mm, 50-100 μm, and 5-10 μm, with a mass ratio of 25-35:45-55:15-25 for the silicon nitride particles of 1-3 mm, 50-100 μm, and 5-10 μm. The average particle size of the nano-Al2O3 is 20-50 nm. The smallest component of the silicon nitride particles forms a silane (SiAlON) oxygen barrier layer in situ with the nano-Al2O3 substrate, filling the pores, improving the interfacial bonding strength, and preventing interfacial delamination and structural disintegration.

[0026] The explosion-proof fiber is 1-8mm long and 0.1-0.6mm in diameter.

[0027] The explosion-proof fiber is selected from at least one of polyethylene fiber and polypropylene fiber.

[0028] The present invention also provides a method for preparing the above-mentioned antioxidant blast furnace tapping trough castable, comprising the following steps:

[0029] The corundum, silicon carbide, silicon nitride, carbonaceous materials, nano-Al2O3, and explosion-proof fibers are mixed evenly, and then a dispersant and binder are added and mixed evenly to obtain the blast furnace tapping trough castable.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] The binder of the blast furnace tapping trough castable of the present invention includes modified phenolic resin, p-aminophenyl POSS, and alcohol solvent. The modified phenolic resin is prepared by reacting formaldehyde, hydroxyphenyl borate ester, and phenol. During high-temperature baking and use, the binder generates a dense, antioxidant Si-BC ceramic phase in situ, which improves the strength, antioxidant properties, and slag erosion resistance of the castable. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments, but is not limited to the contents of the specification. Unless otherwise specified, all "parts" mentioned in the embodiments of the present invention are parts by weight. All reagents used are commercially available in the art.

[0033] The graphite has an average particle size of 0.1 mm and comes from Qingdao Yucheng Graphite Co., Ltd.

[0034] Nano Al2O3, catalog number A431930, with an average particle size of 40nm, is from Aladdin.

[0035] The polyethylene fibers are 3mm long and 0.12mm in diameter, and come from Shandong Oude Chemical Fiber Products Co., Ltd.

[0036] The silicon nitride iron contains 48.6% Si, 15.3% Fe, and 33.8% N, and comes from Henan Zhongzheng Baoming New Materials Co., Ltd.

[0037] Example 1

[0038] 1) Mix 37wt% formaldehyde aqueous solution containing 2mol formaldehyde, 0.25mol 4-hydroxyphenylboronic acid pinacol ester, 0.75mol phenol, and sodium hydroxide (0.8wt% of the mass of formaldehyde, 4-hydroxyphenylboronic acid pinacol ester, phenol) with water. Heat the mixture to 80℃ and react for 3h. After the reaction, dry the mixture at 70℃ under vacuum of 0.07MPa for 3h to obtain modified phenolic resin.

[0039] 2) Add 80 parts by weight of modified phenolic resin and 20 parts by weight of p-aminophenyl POSS to a stirred tank, add ethanol until the solid content is 60 wt%, mix evenly to obtain a binder.

[0040] 3) Mix 75 parts by weight of corundum, 25 parts by weight of silicon carbide, 15 parts by weight of silicon nitride iron, 10 parts by weight of graphite, 6 parts by weight of nano Al2O3, and 10 parts by weight of polyethylene fiber, add 0.5 parts by weight of stearic acid and 40 parts by weight of binder and mix well to obtain blast furnace tapping trough castable.

[0041] Brown fused alumina: The grain size composition is 1-1.5mm and 1.5-5mm, and the mass ratio of the two grain sizes is 1:5.

[0042] Silicon carbide: The particle size composition is 1-3mm and 0.05-0.15mm, and the mass ratio of the two particle sizes is 1:2.

[0043] Silicon nitride: 1-3mm, 50-100μm, 5-10μm, with a mass ratio of 30:50:20 for the three different particle sizes.

[0044] Example 2

[0045] The rest is the same as in Example 1, except that in step 3), the amount of binder used is 20 parts by mass.

[0046] Example 3

[0047] The rest is the same as in Example 1, except that in step 2), the amount of modified phenolic resin is 70 parts by weight and the amount of p-aminophenyl POSS is 30 parts by weight.

[0048] Example 4

[0049] The rest is the same as in Example 1, except that in step 2), the amount of modified phenolic resin is 60 parts by mass and the amount of p-aminophenyl POSS is 40 parts by mass.

[0050] Example 5

[0051] The rest is the same as in Example 1, except that in step 1), 3-hydroxyphenylboronic acid pinacol ester is used instead of 4-hydroxyphenylboronic acid pinacol ester.

[0052] Example 6

[0053] The rest is the same as in Example 1, except that in step 1), the amount of 4-hydroxyphenylboronic acid pinacol ester is 0.15 mol and the amount of phenol is 0.85 mol.

[0054] Example 7

[0055] 1) Mix 37wt% formaldehyde aqueous solution containing 1.5mol formaldehyde, 0.25mol 4-hydroxyphenylboronic acid pinacol ester, 0.75mol phenol, and sodium hydroxide (0.4wt% of the mass of formaldehyde, 4-hydroxyphenylboronic acid pinacol ester, phenol, etc.) and heat to 65℃ for 6h. After the reaction is completed, dry the mixture at 70℃ under vacuum of 0.07MPa for 3h to obtain modified phenolic resin.

[0056] 2) Add 80 parts by weight of modified phenolic resin and 20 parts by weight of p-aminophenyl POSS to a stirred tank, add ethanol until the solid content is 40 wt%, mix evenly to obtain a binder.

[0057] 3) Mix 55 parts by weight of corundum, 15 parts by weight of silicon carbide, 25 parts by weight of silicon nitride iron, 5 parts by weight of graphite, 4 parts by weight of nano Al2O3, and 5 parts by weight of polyethylene fiber. Add 0.1 parts by weight of stearic acid and 40 parts by weight of binder and mix well to obtain blast furnace tapping trough castable.

[0058] Brown fused alumina: The grain size composition is 1-1.5mm and 1.5-5mm, and the mass ratio of the two grain sizes is 1:3.

[0059] Silicon carbide: The particle size composition is 1-3mm and 0.05-0.15mm, and the mass ratio of the two particle sizes is 1:4.

[0060] Silicon nitride: 1-3mm, 50-100μm, 5-10μm, with a mass ratio of 25:55:20 for the three different particle sizes.

[0061] Comparative Example 1

[0062] The rest is the same as in Example 1, except that in step 2), p-aminophenyl POSS is replaced with an equal mass of modified phenolic resin.

[0063] Comparative Example 2

[0064] The rest is the same as in Example 1, except that in step 1), phenol is used instead of 4-hydroxyphenylboronic acid pinacol ester.

[0065] The furnace tapping trough castables prepared in the above embodiments and comparative examples were subjected to the following performance tests:

[0066] 1. Flexural strength: Refer to the standard GB / T 3002-2017 Test method for flexural strength of refractory materials at room temperature. Pour the castable refractory from the furnace outlet into the mold, vibrate and cast, let it stand at room temperature for 24 hours, demold, place the test sample in an oven at 110℃ for 24 hours to dry and allow the resin to initially crosslink, harden at 175℃ for 1 hour, and fire at 1500℃ for 3 hours and then cool naturally in the furnace to test the flexural strength.

[0067] 2. Antioxidant Test: Following the standard GB / T 17732-2023, Test Method for Dense Shaped Carbon-Containing Refractory Products, the castable was placed in a 50mm×50mm×50mm mold, vibrated during casting, and cured at room temperature for 24 hours. After demolding, it was placed in an oven at 110℃ for 24 hours to allow initial cross-linking of the resin, then hardened at 175℃ for 1 hour. Air was passed through at a flow rate of 4L / min, and the sample was fired at 1500℃ for 3 hours. After natural cooling in the furnace, photographs were taken, and the oxide layer and cross-sectional area were measured using ImageJ software. The oxide area percentage was calculated using the following formula: Oxidation area percentage = S0 / S × 100%, where S0 is the oxide area of ​​the sample (mm²). 2 S is the cross-sectional area of ​​the sample (mm²). 2 ).

[0068] 3. Slag Resistance Test: Referring to the standard GB / T 8931-2007 Test Method for Slag Resistance of Refractory Materials, the static crucible method was used for testing. The castable was placed in a 70mm×70mm×70mm slag-resistant steel mold, vibrated and cast, and cured at room temperature for 24 hours. After demolding, it was placed in an oven at 110℃ for 24 hours to dry and allow the resin to undergo preliminary cross-linking. It was then hardened at 175℃ for 1 hour. A crucible with an inner diameter of 40mm and a depth of 35mm was drilled from the center of the top surface of the sample. The crucible was filled with crushed slag that had passed through a 0.5mm sieve. After heat treatment at 1500℃ for 3 hours in a high-temperature furnace, the sample was cut along the center line, and the slag line erosion depth of the sample profile was measured.

[0069] Chemical composition of slag: 56% SiO2, 17.03% Al2O3, 5.01% Fe2O3, 12.3% CaO, 2.65% MgO, 2.32% K2O, 1.81% Na2O, 1.00% TiO2, 0.16% MnO, 0.18% P2O5, 0.82% SO3.

[0070] Table 1 Performance Test Results

[0071]

[0072] As shown in Table 1, the blast furnace taphole castable of this application possesses excellent strength, oxidation resistance, and slag erosion resistance. The flexural strength after hardening is 5.2-6.4 MPa, and the flexural strength after firing at 1500℃ for 3 hours is 12.7-14.8 MPa. The oxidation area ratio is 0.9-4.6%, and the erosion depth is 0.7-2.8 mm. The examples and comparative examples clearly demonstrate that only by introducing boron in the form of hydroxyphenyl borate ester into the modified phenolic resin, and simultaneously introducing p-aminephenyl POSS in specific amounts and proportions, can the purpose of improving the strength, oxidation resistance, and slag erosion resistance of the castable be achieved.

[0073] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. An antioxidant blast furnace tapping trough castable, characterized in that, The raw materials include the following parts by weight: 55-75 parts corundum, 15-25 parts silicon carbide, 15-25 parts silicon nitride iron, 5-10 parts carbonaceous material, 4-6 parts nano Al2O3, 0.1-0.5 parts dispersant, 20-40 parts binder, and 5-10 parts explosion-proof fiber. The binder raw materials include modified phenolic resin, p-aminophenyl POSS, and alcohol solvent. The modified phenolic resin is obtained by polycondensation of formaldehyde, hydroxyphenyl borate ester, and phenol.

2. The blast furnace tapping trough castable according to claim 1, characterized in that, The modified phenolic resin and p-aminophenyl POSS have a mass ratio of 6-8:2-4, preferably 7-8:2-3; the modified phenolic resin is prepared by polycondensation of formaldehyde, hydroxyphenyl borate ester, and phenol in a molar ratio of 1.5-2:0.15-0.25:0.75-0.

85.

3. The blast furnace tapping trough castable according to claim 1, characterized in that, The hydroxyphenylboronic acid ester is selected from at least one of 4-hydroxyphenylboronic acid pinacol ester, 3-hydroxyphenylboronic acid pinacol ester, and 2-(4,4,5,5-tetramethyl-1,3,2-diaxopentylborane-2-yl)phenol; the formaldehyde is in the form of a 35-40 wt% aqueous formaldehyde solution.

4. The blast furnace tapping trough castable according to claim 1, characterized in that, The binder is prepared by a method comprising the following steps: 1) Formaldehyde, hydroxyphenyl borate, phenol, and catalyst are mixed, heated to react, and dehydrated to obtain modified phenolic resin. 2) Mix the modified phenolic resin, p-aminophenyl POSS, and alcohol solvent to obtain the binder.

5. The blast furnace tapping trough castable according to claim 4, characterized in that, The catalyst is selected from at least one of potassium hydroxide, sodium hydroxide, and calcium hydroxide; the amount of the catalyst is 0.4-0.8 wt% of the sum of the masses of formaldehyde, hydroxyphenyl borate, and phenol.

6. The blast furnace tapping trough castable according to claim 1, characterized in that, The binder has a solid content of 40-60 wt%; the alcohol solvent is selected from at least one of ethanol, ethylene glycol, isopropanol, and glycerol.

7. The blast furnace tapping trough castable according to claim 1, characterized in that, The dispersant is selected from at least one of stearic acid, oleic acid, zinc stearate, and magnesium stearate.

8. The blast furnace tapping trough castable according to claim 1, characterized in that, The carbonaceous material is selected from at least one of graphite and amorphous carbon; the average particle size of the carbonaceous material is 0.1-0.3 mm; the explosion-proof fiber is 1-8 mm long and 0.1-0.6 mm in diameter; the explosion-proof fiber is selected from at least one of polyethylene fiber and polypropylene fiber.

9. The blast furnace tapping trough castable according to claim 1, characterized in that, The corundum is selected from at least one of tabular corundum, fused white corundum, sub-white corundum, brown corundum, and dense corundum; the corundum has a particle size composition of 1-1.5 mm and 1.5-5 mm, with a mass ratio of 1-1.5 mm to 1.5-5 mm corundum at 1:3-5; the silicon carbide has a particle size composition of 1-3 mm and 0.05-0.15 mm, with a mass ratio of 1-3 mm to 0.05-0.15 mm silicon carbide at 1:3-5. The silicon nitride composition is 1:2-4; the silicon nitride contains 45-50% Si, 14-17% Fe, and 25-35% N; the silicon nitride has a particle size distribution of 1-3 mm, 50-100 μm, and 5-10 μm, and the mass ratio of silicon nitride with particle sizes of 1-3 mm, 50-100 μm, and 5-10 μm is 25-35:45-55:15-25; the average particle size of the nano-Al2O3 is 20-50 nm.

10. The method for preparing the blast furnace tapping trough castable according to any one of claims 1-9, characterized in that, Includes the following steps: The corundum, silicon carbide, silicon nitride, carbonaceous materials, nano-Al2O3, and explosion-proof fibers are mixed evenly, and then a dispersant and binder are added and mixed evenly to obtain the blast furnace tapping trough castable.

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