Anhydrous stemming, preparation method and application

Abstract

The invention provides anhydrous stemming as well as a preparation method and application thereof, and relates to the technical field of refractory materials. According to the present invention, 40-45 parts of high bauxite clinker, 20-25 parts of corundum, 10-15 parts of natural crystalline flake graphite and other raw materials are matched, 0.4-0.9 part of micro-nano composite aluminum powder composed of 15-25 [mu] m micron aluminum powder and 400-600 nm nano aluminum powder is adopted, 0.1-0.3 part of nano manganese dioxide is matched, such that gradient oxidation is achieved, permeation resistance and anti-scouring performance are improved, the breaking strength retention rate after thermal shock cycle is more than or equal to 80%, and the anti-permeation and anti-scouring performance is good; the service life is prolonged and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refractory materials, in particular to a waterless tamping clay, a preparation method and application. BACKGROUND

[0002] In the key link of blast furnace smelting, the taphole is the core channel for the discharge of molten iron and slag, and its working condition is extremely harsh. Since it needs to undergo frequent opening and closing operations, the temperature of the waterless tamping clay will rapidly alternate between room temperature and above 1500℃, which puts extremely high requirements on the performance of the waterless tamping clay. The carbonaceous materials such as graphite in the waterless tamping clay provide important structural support and erosion resistance in high-temperature environments due to their excellent high-temperature resistance and chemical stability, but graphite is prone to oxidation at high temperatures, and excessive oxidation will cause the tamping clay structure to be loose and the strength to decrease, affecting the service life and protection effect. Therefore, metal additives are usually added, and aluminum powder is preferentially oxidized to form an Al2O3 protective layer at high temperatures, which covers the surface of the graphite to block the contact between oxygen and graphite, thereby protecting the graphite. However, in actual application, the oxidation rates of carbonaceous materials and metal additives are difficult to dynamically match. The frequent opening and closing of the blast furnace taphole bring about drastic and rapid temperature changes, and when the temperature rapidly rises, the oxidation of aluminum powder may be too intense, causing the Al2O3 protective layer to be generated too quickly and in excess, and when the temperature subsequently decreases, the excess protective layer will generate a large stress with the graphite matrix due to thermal expansion and contraction; while the temperature rises slowly or is in a lower temperature range, the oxidation of aluminum powder is slow, and the generated Al2O3 protective layer is insufficient to effectively block oxygen, which will cause the graphite to oxidize prematurely. At the same time, differences in particle size, purity, etc. of different batches of aluminum powder and graphite will also affect the oxidation rate, exacerbating the mismatch problem. This problem further causes the interface between the Al2O3 protective layer generated by the oxidation of aluminum powder and the oxidation-resistant layer of graphite to peel off, forming a gap between the two, through which high-temperature molten iron and slag can penetrate into the tamping clay. On the one hand, the high-speed flow of molten iron and slag produces strong erosion on the material around the gap, accelerating the wear of the tamping clay, and on the other hand, the penetration of molten iron and slag into the tamping clay causes chemical reactions with other components of the tamping clay, destroying the overall structure and reducing the strength and stability, leading to a sharp decrease in the erosion resistance of the tamping clay, an accelerated expansion of the taphole, an impact on the normal tapping rhythm of the blast furnace, and even the possibility of safety accidents, increasing production costs and maintenance difficulty, especially in large blast furnaces and super-high furnace age blast furnaces, which has become a key technical problem that needs to be solved in the current steel smelting field. SUMMARY

[0003] In order to solve the above-mentioned defects and deficiencies in the prior art, the present application aims to provide a waterless tamping clay, a preparation method and application.

[0004] One of the objects of the present application is to provide a waterless tamping clay comprising the following raw materials by weight: high alumina bauxite clinker 40-45 parts, corundum 20-25 parts, natural flake graphite 10-15 parts, carbon black 5-8 parts, carbon fiber 3-5 parts, micro-nano composite aluminum powder 0.4-0.9 parts, nano manganese dioxide 0.1-0.3 parts, boron carbide 0.5-1 parts, coke powder 5-8 parts, nano silicon dioxide 2-3 parts, phenolic resin 7-10 parts; The micro-nano composite aluminum powder is a mixture of 15-25 mu m micron aluminum powder and 400-600 nm nano aluminum powder.

[0005] Preferably, the mass ratio of the micron aluminum powder and the nano aluminum powder is 2-4:1.

[0006] Preferably, the Al2O3 content in the high alumina bauxite clinker is 70%-80%; the Al2O3 content in the corundum is 90%-100%.

[0007] Preferably, the length of the carbon fiber is 0.5-1 mm.

[0008] Preferably, the particle size of the nano manganese dioxide is 20-50 nm, the fixed carbon content of the coke powder is ≥85%, and the particle size of the nano silicon dioxide is 50-100 nm.

[0009] The second object of the present application is to provide a preparation method of the anhydrous stemming as described above, comprising the following steps: S1, uniformly mixing the micro-nano composite aluminum powder and the first part of the phenolic resin to obtain slow-release aluminum powder; mixing the high alumina bauxite clinker, the corundum, the natural flake graphite, the carbon black, the carbon fiber, and the coke powder to obtain a first mixture; S2, mixing the slow-release aluminum powder, the first mixture, the nano manganese dioxide, the boron carbide, and the nano silicon dioxide to obtain a second mixture; S3, mixing and kneading the second mixture and the second part of the phenolic resin to obtain a third mixture; S4, molding and curing the third mixture to obtain the anhydrous stemming.

[0010] Preferably, the mass ratio of the first part of the phenolic resin to the micro-nano composite aluminum powder is 5-8:100.

[0011] Preferably, the mixing and kneading of the second mixture and the second part of the phenolic resin to obtain the third mixture comprises: mixing the second mixture and the second part of the phenolic resin, heating to 110-130 DEG C, and holding for 20-40 min; continuing to heat to 170-200 DEG C, and holding for 20-40 min to obtain the third mixture.

[0012] The second object of the present application is to provide a preparation method of the anhydrous stemming as described above, comprising the following steps:

[0013] The beneficial effects of the present application are as follows: The present application realizes gradient oxidation by proportioning 40-45 parts of bauxite clinker, 20-25 parts of corundum, 10-15 parts of natural flake graphite and other raw materials, 0.4-0.9 parts of micro-nano composite aluminum powder composed of 15-25 μm micron aluminum powder and 400-600 nm nano aluminum powder, 0.1-0.3 parts of nano manganese dioxide, the nano aluminum powder forms an initial Al2O3 protective layer at low temperature, the micron aluminum powder continuously supplements at medium and high temperatures, and dynamically matches with graphite oxidation to reduce graphite oxidation, 2-3 parts of nano silicon dioxide promotes the generation of strong chemical bonds at the interface and inhibits peeling, and 7-10 parts of phenolic resin improves the density, so that the permeability resistance and scouring resistance of the ramming mass are significantly optimized, and the ramming mass is suitable for harsh working conditions of a blast furnace.

[0014] At the same time, 0.5-1 parts of boron carbide generate B2O3 glass phase to protect graphite, 5-8 parts of coke powder balance reaction heat to avoid decomposition of the protective layer, 3-5 parts of carbon fiber relieve thermal stress, high refractory aggregate enhances high-temperature stability, so that the ramming mass has a bending strength retention rate of ≥80% after thermal shock cycle, prolongs the service life, and reduces the production cost. DETAILED DESCRIPTION

[0015] The present application will be further described in detail below in conjunction with examples. The specific examples described herein are only used to explain the related application, and are not a limitation on the application. The examples in the present application and the features in the examples can be combined with each other without conflict. The present application will be described in detail below in conjunction with examples.

[0016] According to a first aspect of the present application, an anhydrous ramming mass is provided, comprising the following raw materials in parts by weight: 40-45 parts of bauxite clinker, 20-25 parts of corundum, 10-15 parts of natural flake graphite, 5-8 parts of carbon black, 3-5 parts of carbon fiber, 0.4-0.9 parts of micro-nano composite aluminum powder, 0.1-0.3 parts of nano manganese dioxide, 0.5-1 parts of boron carbide, 5-8 parts of coke powder, 2-3 parts of nano silicon dioxide, and 7-10 parts of phenolic resin. The micro-nano composite aluminum powder is a mixture of 15-25 μm micron aluminum powder and 400-600 nm nano aluminum powder.

[0017] In the present application, high bauxite clinker and corundum are refractory aggregates, which provide high-temperature structural strength and anti-erosion foundation as the matrix framework of anhydrous stopper. The high bauxite clinker contains 70%-80% of Al2O3, has moderate cost and excellent high-temperature stability, and can maintain structural integrity above 1500℃; the corundum has an Al2O3 content of 90%-100%, high hardness and strong wear resistance, and can resist the scouring and erosion of high-temperature molten iron and slag. The two together account for 60-70 parts, with the highest proportion, ensuring the density and anti-deformation ability of the matrix framework, and avoiding the melting of stopper by molten iron at high temperature due to insufficient aggregate. Natural flake graphite, carbon black and carbon fiber are used as carbonaceous materials. Graphite provides high-temperature resistance and lubricity, facilitating the opening and closing of the taphole, but it is easy to oxidize; nano-sized carbon black can fill the gaps between graphite particles, enhancing the oxidation resistance; carbon fiber disperses thermal stress through bridging action, improving thermal shock resistance and reducing cracking caused by temperature difference alternation. The three together account for 18-28 parts, ensuring the high-temperature supporting role of graphite, and compensating for its oxidation resistance and toughness defects through carbon black and carbon fiber, avoiding the problems of rapid oxidation or excessive brittleness caused by single carbonaceous material.

[0018] Nano-MnO2 can act as an electron transfer bridge to reduce the aluminum powder oxidation initiation temperature from 500℃ to 400℃, ensuring the rapid formation of an Al2O3 protective layer at a low temperature stage, shielding graphite in advance and avoiding graphite exposure to oxidation at a low temperature stage. At high temperatures, it reacts with graphite to form a B2O3 glass phase with a melting point of 450℃, covering the surface of graphite and filling micro-cracks, reducing the oxidation rate of graphite by 50%-70%, forming a double-oxidation barrier with the aluminum powder protective layer. Coke powder slowly carbonizes to release heat at 800-1000℃, which is staggered with the exothermic oxidation of aluminum powder, avoiding the decomposition of the Al2O3 protective layer caused by local temperature rise. Nano-SiO2 reacts with Si-O-Al and Si-O-C chemical bonds at the interface between the Al2O3 protective layer and graphite, improving the interface bonding strength, solving the interface peeling problem, and avoiding the penetration of molten iron and slag from the interface gap. Phenolic resin is partially used to coat aluminum powder to form a slow-release shell layer, reducing the pre-oxidation loss of aluminum powder, and the rest is used as a binder to give the stopper plasticity, ensuring the tight bonding of particles of each raw material, improving the initial strength and density after molding, and reducing the penetration channel of molten iron.

[0019] The micro-nano composite aluminum powder solves the problem of matching the oxidation rate with graphite by gradient oxidation. The specific surface area of the nano aluminum powder is large, and it can be quickly oxidized to generate an initial Al2O3 protective layer at 300-500 DEG C; the reaction activity of the micron aluminum powder is relatively low, and it is slowly oxidized at 800-1200 DEG C to continuously supplement the protective layer, avoiding the problems of insufficient protection at low temperature or failure of the protective layer at high temperature. The use amount of 0.4-0.9 parts can balance the amount of oxidation products, and too little will result in insufficient protective layer, and too much will result in excessive heat release during oxidation, causing excessive local stress, and forming a dynamic matching with the oxidation demand of graphite, avoiding the failure of the protective layer caused by too fast or insufficient oxidation of the traditional ramming mixture, and laying a foundation for subsequent interface peeling inhibition and performance improvement.

[0020] In a preferred embodiment of the present application, the mass ratio of the micron aluminum powder to the nano aluminum powder is 2-4:1.

[0021] In the present application, the mass ratio of the micron aluminum powder to the nano aluminum powder is 2-4:1, which can accurately match the oxidation characteristics of graphite in different temperature ranges. The nano aluminum powder has a large specific surface area and high reaction activity, and it can be quickly oxidized to generate an initial Al2O3 protective layer at 300-500 DEG C low temperature section, and its proportion needs to meet the low temperature fast film forming demand, otherwise the lack of nano aluminum powder will result in the absence of low temperature protective layer, and the graphite is easy to be oxidized in advance; the micron aluminum powder has relatively low reaction activity, and it is slowly oxidized at 800-1200 DEG C medium-high temperature section to continuously supplement the protective layer, and its proportion needs to guarantee the protection potential at medium-high temperature stage, if the proportion of coarse powder is too low, the protective layer is insufficient at medium-high temperature, and it is easy to cause protection failure due to erosion and decomposition. From the perspective of thermal stress balance, the mass ratio of the micron aluminum powder to the nano aluminum powder is 2-4:1, which can avoid the interface stress problem caused by the imbalance of the oxidation rate of aluminum powder. If the mass ratio of the micron aluminum powder to the nano aluminum powder is less than 2:1, the oxidation is too violent at low temperature, the generated Al2O3 protective layer is excessive, the difference between thermal expansion and cold shrinkage with the graphite matrix increases during cooling, and cracks are easy to occur; if the mass ratio of the micron aluminum powder to the nano aluminum powder is higher than 4:1, the oxidation product is slowly supplemented at high temperature, the thickness of the protective layer is insufficient, and it cannot resist the iron water erosion, and the difference between the oxidation rates of the two may aggravate the interface peeling risk.

[0022] In addition, the ratio of 2-4:1 forms a synergy with other components, which can quickly respond to the low temperature oxidation demand through the nano aluminum powder, and can rely on the coarse powder to maintain the continuity of the medium-high temperature protection, and finally realizes the dynamic matching of aluminum powder oxidation and graphite oxidation, providing a basis for the erosion resistance, permeability resistance and thermal shock stability of the ramming mixture.

[0023] In a preferred embodiment of the present application, the length of the carbon fiber is 0.5-1 mm.

[0024] In the present application, the length of carbon fiber is limited to 0.5-1mm, mainly based on its reinforcing and toughening effect in anhydrous gunning and the synergistic compatibility with other raw materials. From the perspective of thermal shock resistance, the length of 0.5-1mm can effectively alleviate the thermal stress caused by alternating high and normal temperature through the bridging effect. The dramatic temperature difference caused by frequent opening and closing of the blast furnace tap hole will cause significant thermal expansion and contraction of the gunning. Carbon fibers of this length can be inserted between refractory aggregates, carbonaceous materials and other particles, like a skeleton, to disperse stress and reduce micro-cracks caused by thermal stress concentration. If the length is shorter than 0.5mm, the bridging effect is weakened and cannot effectively span the gap between particles, limiting the improvement of thermal shock resistance. If the length is longer than 1mm, the carbon fibers are easy to intertwine and agglomerate during mixing, leading to uneven dispersion and even forming stress weak points in local areas, reducing the overall structural stability of the gunning. From the compatibility with other components, the length matches the particle size of the raw materials and the density of the gunning. The particle size of the refractory aggregate and the carbonaceous material complements the 0.5-1mm carbon fiber, ensuring sufficient contact between the carbon fiber and the matrix material, and not affecting the uniformity of the material mixing and the density after compression molding. If the length is too long, the internal porosity may increase due to fiber interweaving during molding, becoming a penetration channel for molten iron or slag, thereby reducing the impermeability. If it is too short, it is difficult to synergistically play a role with reinforcing agents such as nano-silica, and it cannot further improve the interfacial bonding strength.

[0025] Therefore, the length of 0.5-1mm of carbon fiber can maximize its role in relieving thermal stress and enhancing thermal shock resistance while ensuring dispersion and density, and synergistically improve the structural stability of anhydrous gunning under extreme working conditions with other components.

[0026] In a preferred embodiment of the present application, the particle size of the nano-manganese dioxide is 20-50nm, the fixed carbon content of the coke powder is ≥85%, and the particle size of the nano-silica is 50-100nm.

[0027] In the present application, the 20-50nm nano-manganese dioxide has a very high specific surface area and surface activity, and can accelerate the start of the aluminum powder oxidation reaction as an electron transfer medium. Its particle size is size-matched with the micro-nano composite aluminum powder, which can uniformly adhere to the surface of the aluminum powder, reduce the activation energy of the oxidation reaction, and make the nano-aluminum powder rapidly oxidize in the low temperature range of 300-500℃, ensuring the timely formation of the initial Al2O3 protective layer. If the particle size is less than 20nm, agglomeration may occur due to the excessively high surface energy, leading to uneven distribution of catalytic sites and ineffective activation of some aluminum powder. If the particle size is greater than 50nm, the specific surface area decreases and the catalytic efficiency decreases, which cannot meet the precise control requirements of aluminum powder gradient oxidation, and may cause the protective layer to be generated late in the low temperature stage, and the graphite to be oxidized early.

[0028] The core function of the coke powder is to release heat through slow carbonization to balance the violent exothermic oxidation of the aluminum powder. The fixed carbon content ≥ 85% means that the impurities are less, and the carbonization reaction can stably occur at 800-1000°C to release heat to offset the local high temperature generated by the concentrated oxidation of the aluminum powder. If the fixed carbon content is less than 85%, the ash will react with Al2O3 and graphite in the stopper at high temperature to form a low-melting-point phase, which destroys the integrity of the Al2O3 protective layer; and if the volatile content is too high, it will quickly escape at high temperature to form pores in the stopper, which becomes a penetration channel for molten iron and slag, reducing the anti-permeability.

[0029] The nano-silicon dioxide with a particle size of 50-100 nm can precisely fill the micro gaps between the Al2O3 protective layer and the graphite, and the particle size matches the interface scale of Al2O3 and graphite, which can generate Si-O-Al and Si-O-C covalent bonds through diffusion reaction, significantly improve the interface bonding strength, and inhibit the interface peeling. If the particle size is less than 50 nm, local enrichment is easy to occur due to agglomeration, which forms stress concentration points at the interface; and if the particle size is greater than 100 nm, it cannot fully penetrate into the fine gaps, the interface filling effect is reduced, it is difficult to construct a continuous reinforcing network with other components, and the improvement of the anti-washing and anti-permeability performance is affected. The above parameters are limited based on the scale matching, functional synergy and performance requirements under extreme working conditions of the raw materials, to ensure that each component precisely plays a role and improves the oxidation resistance, peeling resistance, washing resistance and permeability resistance of the anhydrous stopper.

[0030] According to a second aspect of the present application, there is provided a method of preparing the anhydrous stopper as described above, comprising the following steps: S1 mixing the micro-nano composite aluminum powder and the first portion of phenolic resin uniformly to obtain a slow-release aluminum powder; mixing the bauxite clinker, corundum, natural flake graphite, carbon black, carbon fiber and coke powder to obtain a first mixture; S2 mixing the slow-release aluminum powder, the first mixture, nano-manganese dioxide, boron carbide and nano-silicon dioxide to obtain a second mixture; S3 mixing and kneading the second mixture and the second portion of phenolic resin to obtain a third mixture; S4 molding and curing the third mixture to obtain the anhydrous stopper.

[0031] In the present application, the phenolic resin includes the first portion of phenolic resin and the second portion of phenolic resin.

[0032] In a preferred embodiment of the present application, mixing the bauxite clinker, corundum, natural flake graphite, carbon black, carbon fiber and coke powder to obtain a first mixture comprises: firstly mixing and stirring the bauxite clinker and the corundum for 5-10 min; Then, natural flake graphite, carbon black, carbon fiber and coke powder are added and stirred for 10-15 minutes to obtain a first mixture.

[0033] In a preferred embodiment of the present application, the mass ratio of the first portion of phenolic resin to the micro-nano composite aluminum powder is 5-8:100.

[0034] In the present application, the phenolic resin forms a coating layer at room temperature, isolating the micro-nano composite aluminum powder from air and inhibiting its pre-oxidation during storage and mixing. Studies have shown that the phenolic resin film thickness under this ratio is 50-100 nm, which can effectively block the penetration of oxygen, and will not affect the oxidation reaction activity of the aluminum powder at high temperature due to the thickness of the film layer. At a high temperature of 300-500℃, the phenolic resin gradually carbonizes and decomposes, releasing aluminum powder to participate in the oxidation reaction. The loading of 5-8% makes the decomposition rate accurately match the gradient oxidation demand of aluminum powder: nano-aluminum powder rapidly oxidizes at 300-400℃ in the early stage of resin decomposition, and micron-aluminum powder is gradually released at 400-500℃ in the continuous decomposition stage of resin, realizing the time sequence control of aluminum powder oxidation, and the synchronization rate with graphite oxidation process is improved to more than 90%. The residual carbon layer of the carbonized phenolic resin forms a transition layer between the aluminum powder and the refractory matrix, and through the C-O-Al bond and C-Si bond in the residual carbon, the interfacial bonding strength between the aluminum powder oxidation product and the matrix material is improved to 18-22MPa, which is 40%-60% higher than that of the uncoated aluminum powder, effectively inhibiting the interfacial peeling caused by thermal stress at high temperature.

[0035] If the ratio is less than 5:100, the coating layer is too thin to provide sufficient oxidation protection, affecting the gradient oxidation effect; if it is higher than 8:100, the amount of gas generated by the resin decomposition is too large, forming air porosity inside the ramming mass, which reduces the impermeability. The ratio range has been verified by experiments to stabilize the erosion and abrasion resistance of the ramming mass at 0.4-0.5g / min, and the penetration depth of molten iron is ≤1mm, and the comprehensive performance is optimal.

[0036] In a preferred embodiment of the present application, mixing the second mixture and the second portion of phenolic resin to obtain a third mixture comprises: Mixing the second mixture and the second portion of phenolic resin, heating to 110-130℃, and holding for 20-40min, and continuing to heat to 170-200℃, holding for 20-40min, to obtain a third mixture.

[0037] In the present application, the process of using gradient temperature rise and segmented temperature holding stirring in the mixing process is designed based on the physicochemical properties of phenolic resin and the requirement of the compact structure of the mortar. The low temperature section of 110-130℃ is used to realize the uniform penetration and preliminary plasticization of the resin. The phenolic resin is in a molten flow state at 110-130℃, with moderate viscosity, which can uniformly penetrate into the interstitial gaps of the second mixture of particles through stirring, and wrap all the surfaces of the solid particles. The temperature holding stirring for 20-40min in this stage can ensure that the resin fully wets the particles of different sizes such as micron aluminum powder, graphite and corundum, and avoid local weak bonding caused by uneven penetration. This temperature section can volatilize a small amount of free formaldehyde and moisture in the resin, reducing the air pores generated by rapid volatilization in the subsequent high temperature stage. At the same time, slow stirring can release the initial stress generated between the particles due to the wrapping of the resin, avoiding micro-cracks caused by stress concentration during the later curing. The high temperature section of 170-200℃ can promote the curing and structure strengthening of the resin. The phenolic resin undergoes a severe condensation reaction at 170-200℃, and the molecular chains cross-link to form a three-dimensional network structure, firmly bonding all solid particles into a whole. This stage is the key to determining the mechanical strength of the mortar, and incomplete curing will result in insufficient bonding, while excessive curing will cause the resin to decompose and generate CO, CH4 and other gases, resulting in an increase in porosity from 1%-2% to more than 5%, significantly reducing the permeation resistance. The temperature range matches the thermal stability of high alumina bauxite clinker, corundum and graphite, and will not cause performance degradation of the raw materials due to high temperature; at the same time, the carbon fiber still maintains its toughness at this temperature, which can synergistically enhance the structure crack resistance with the cured resin. The temperature holding stirring for 20-40min ensures that the reaction in each temperature section proceeds sufficiently, and avoids increasing energy consumption or over-crosslinking of the resin due to excessive time. Over-crosslinking will increase the brittleness of the mortar and reduce the thermal shock stability. The gradient temperature mixing precisely controls the penetration and curing process of the phenolic resin, ensuring uniform bonding of the resin to all raw materials, and avoiding defects such as air holes and cracks, and finally forming a compact and strong overall structure of the mortar, which provides a process guarantee for its core performance of anti-erosion and anti-permeation.

[0038] According to a third aspect of the present application, there is provided a use of the anhydrous mortar as described above for a blast furnace taphole.

[0039] Example 1 An anhydrous mortar is prepared by the following method: S1: uniformly mix 0.4 parts of micro-nano composite aluminum powder and 0.024 parts of the first phenolic resin to obtain a slow-release aluminum powder; the micro-nano composite aluminum powder is a mixture of 15μm coarse powder and 400nm nano aluminum powder, and the mass ratio of the coarse powder to the nano aluminum powder is 4:1; Mix 40 parts of high alumina bauxite clinker (Al2O3 content of 75%) and 25 parts of corundum (Al2O3 content of 95%) first, stir for 5-10 min; Then add 10 parts of natural flake graphite, 7 parts of carbon black, 4 parts of carbon fiber with a length of 0.8 mm and 6 parts of coke powder with a fixed carbon content of 90%, stir for 10-15 min to obtain a first mixture; S2 mix the slow-release aluminum powder, the first mixture, 0.3 parts of nano manganese dioxide with a particle size of 40 nm, 0.8 parts of boron carbide and 2.5 parts of nano silicon dioxide to obtain a second mixture; S3 mix the second mixture and 7.976 second parts of phenolic resin, heat to 120℃, and keep stirring for 30 min, continue to heat to 180℃, and keep stirring for 30 min to obtain a third mixture; S4 the third mixture is pressed into a green body under a forming pressure of 15-20 MPa; the formed green body is placed in a ventilated drying place for 24-48 hours for natural curing, and the finished anhydrous stemming is obtained.

[0040] Example 2 In this example, 42 parts of high alumina bauxite clinker, 22 parts of corundum and 12 parts of graphite are used; the micro-nano composite aluminum powder is a mixture of 20μm coarse powder and 500nm nano aluminum powder, 0.6 parts; the mass ratio of coarse powder to nano aluminum powder is 2:1; other raw materials and steps are the same as in Example 1.

[0041] Example 3 In this example, 45 parts of high alumina bauxite clinker, 20 parts of corundum and 15 parts of graphite are used; the micro-nano composite aluminum powder is a mixture of 25μm coarse powder and 600nm nano aluminum powder, 0.9 parts; the mass ratio of coarse powder to nano aluminum powder is 3:1; other raw materials and steps are the same as in Example 1.

[0042] Example 4 In this example, 5 parts of carbon black, 5 parts of carbon fiber and 5 parts of coke powder are used; the micro-nano composite aluminum powder is a mixture of 18μm coarse powder and 450nm nano aluminum powder, 0.5 parts; the mass ratio of coarse powder to nano aluminum powder is 4:1; other raw materials and steps are the same as in Example 1.

[0043] Example 5 In this example, 7 parts of carbon black, 3 parts of carbon fiber and 8 parts of coke powder are used; the micro-nano composite aluminum powder is a mixture of 22μm coarse powder and 550nm nano aluminum powder, 0.7 parts; the mass ratio of coarse powder to nano aluminum powder is 3:1; other raw materials and steps are the same as in Example 1.

[0044] Example 6 In this embodiment, 2 parts of nano-silica, 0.5 parts of boron carbide, 0.8 parts of micro-nano composite aluminum powder which is a mixture of 15 μm coarse powder and 600 nm nano-aluminum powder, and the mass ratio of coarse powder to nano-aluminum powder is 3:1; other raw materials and steps are the same as in Example 1.

[0045] Example 7 In this embodiment, 3 parts of nano-silica, 1 part of boron carbide, 0.6 parts of micro-nano composite aluminum powder which is a mixture of 25 μm coarse powder and 400 nm nano-aluminum powder, and the mass ratio of coarse powder to nano-aluminum powder is 3:1; other raw materials and steps are the same as in Example 1.

[0046] Example 8 In this embodiment, 7 parts of phenolic resin (0.024 parts of the first part of phenolic resin and 6.976 parts of the second part of phenolic resin), 0.3 parts of nano-MnO2, 0.9 parts of micro-nano composite aluminum powder which is a mixture of 20 μm coarse powder and 500 nm nano-aluminum powder, and the mass ratio of coarse powder to nano-aluminum powder is 3:1; other raw materials and steps are the same as in Example 1.

[0047] Comparative Example 1 In this comparative example, the micro-nano composite aluminum powder is replaced by single 15-25 μm micron aluminum powder, 0.6 parts, and the rest of the raw materials and amounts are the same as in Example 2.

[0048] Comparative Example 2 In this comparative example, the amount of micro-nano composite aluminum powder is 1.5 parts, the mass ratio of coarse powder to nano-aluminum powder is 3:1, and the rest is the same as in Example 3.

[0049] Comparative Example 3 In this comparative example, nano-silica is replaced by 2.5 parts of 5 μm micron grade SiO2, and the rest is the same as in Example 1.

[0050] Comparative Example 4 In this comparative example, the mixing temperature is directly raised to 180℃, and the rest of the raw materials and steps are the same as in Example 2.

[0051] Comparative Example 5 In this comparative example, the high temperature section is raised to 220℃, and the rest is the same as in Example 3.

[0052] Performance test 1. Anti-washing performance Simulate the working condition of high furnace molten iron turbulent washing, use rotating washing test, washing speed 2-3 m / s, temperature 1500℃, test the wear amount after 30 min; 2. Anti-infiltration performance High temperature infiltration test: at 1500℃, press the molten iron to the taphole sample at 0.2 MPa pressure, test the molten iron infiltration depth after 30 min; 3. Thermal shock stability Thermal shock cycle test: after 5 cycles of 1500℃→room temperature, test the bending strength, and then calculate the ratio of the strength after thermal shock to the initial bending strength before thermal shock, that is, the bending strength retention rate, to evaluate the structural stability under temperature difference alternation; Calculation formula: retention rate=(bending strength after thermal shock / bending strength before thermal shock)×100%.

[0053] The test results are shown in Table 1: Table 1 Performance test results

[0054] The example adopts a composite system of 15-25 μm micron aluminum powder and 400-600 nm nano aluminum powder. The nano aluminum powder forms an initial Al2O3 protective layer at 300-500℃, and the micron aluminum powder continuously supplements at 800-1200℃, dynamically matching with graphite oxidation. The wear rate in Example 3 is only 0.43 g / min, avoiding the loose structure caused by excessive graphite oxidation. 2-3 parts of 50-100 nm nano silicon dioxide strengthens the interface by generating Si-O-Al / C chemical bonds, and the penetration depth in Example 7 is only 0.7 mm. 7-10 parts of phenolic resin are mixed by gradient temperature rise to ensure the structure is dense and reduce the penetration channel of molten iron. The retention rate in Example 2 is 82%, and the bridging effect of 0.5-1 mm carbon fiber balances the reaction heat with coke powder, with fixed carbon ≥85%, which makes the strength retention rate after thermal shock significantly higher than that of traditional ramming mass (<60%).

[0055] The performance of the comparative examples significantly decreases due to deviation from the raw material composition of claim 1 or the mixing process of claim 9, confirming the irreplaceability of key technical features. Comparative Example 1 uses only micron aluminum powder, which lacks nano aluminum powder, resulting in the absence of a low-temperature protective layer, premature oxidation of graphite, an increase in wear rate to 0.85 g / min, and a penetration depth of 3.2 mm, confirming that micron-nano composite aluminum powder gradient oxidation is the core of matching graphite oxidation. In Comparative Example 2, the amount of aluminum powder is excessive, and the oxidation of 1.5 parts of aluminum powder releases a large amount of heat, causing local high temperature to damage the Al2O3 protective layer, increasing the porosity to 8%, and the thermal shock retention rate is only 50%. The use of 0.4-0.9 parts is crucial to balance the oxidation products and stress. In Comparative Example 3, 5 μm SiO2 cannot fill the interface gap, and interface peeling leads to a penetration depth of 4.0 mm. Therefore, 50-100 nm nano SiO2 is a necessary condition to prevent peeling. In Comparative Examples 4-5, direct high-temperature or over-temperature mixing leads to uneven resin penetration and excessive decomposition, increasing the porosity to 9% and the wear rate to more than 1.0 g / min. Gradient temperature rise is the core process to ensure bonding strength and density.

[0056] In summary, the performance test data fully verify that the present application effectively solves the problems of mismatched oxidation rate, interface peeling, poor resistance to erosion / permeation, etc. by gradient oxidation of micro-nano composite aluminum powder, interface strengthening of nano additives, and gradient warming mixing.

Claims

1. An anhydrous taphole mud, characterized in that: The invention comprises the following raw materials in parts by weight: 40-45 parts of high-alumina bauxite clinker, 20-25 parts of corundum, 10-15 parts of natural flake graphite, 5-8 parts of carbon black, 3-5 parts of carbon fiber, 0.4-0.9 parts of micro-nano composite aluminum powder, 0.1-0.3 parts of nano manganese dioxide, 0.5-1 parts of boron carbide, 5-8 parts of coke powder, 2-3 parts of nano silicon dioxide, 7-10 parts of phenolic resin; The micro-nano composite aluminum powder is a mixture of 15-25 μm micron aluminum powder and 400-600 nm nano aluminum powder.

2. The anhydrous taphole mud according to claim 1, characterized in that The mass ratio of the micron aluminum powder to the nano aluminum powder is 2-4:

1.

3. The anhydrous taphole mud according to claim 1, characterized in that The Al2O3 content in the high-alumina bauxite clinker is 70%-80%; the Al2O3 content in the corundum is 90%-100%.

4. The anhydrous taphole mud according to claim 1, characterized in that The length of the carbon fiber is 0.5-1 mm.

5. The anhydrous taphole mud according to claim 1, characterized in that The particle size of the nano manganese dioxide is 20-50 nm, the fixed carbon content of the coke powder is ≥85%, and the particle size of the nano silicon dioxide is 50-100 nm.

6. A method for preparing anhydrous taphole mud according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: uniformly mixing the micro-nano composite aluminum powder and the first portion of phenolic resin to obtain a slow-release aluminum powder; uniformly mixing high-alumina bauxite clinker, corundum, natural flake graphite, carbon black, carbon fiber, and coke powder to obtain a first mixture; S2 mixing the slow-release aluminum powder, the first mixture, nano manganese dioxide, boron carbide and nano silicon dioxide to obtain a second mixture; S3 mixing the second mixture and the second phenolic resin to obtain a third mixture; The S4 third mixture is pressed, formed and solidified to obtain anhydrous taphole mud.

7. The preparation method according to claim 6, wherein The mixing of high-alumina bauxite clinker, corundum, natural flake graphite, carbon black, carbon fiber and coke powder to obtain a first mixture comprises: First mix high alumina clinker and corundum, stirring for 5-10 minutes; Natural flake graphite, carbon black, carbon fiber and coke powder are then added and stirred for 10-15 minutes to obtain a first mixture.

8. The preparation method according to claim 6, wherein The mass ratio of the first phenolic resin to the micro-nano composite aluminum powder is 5-8:

100.

9. The preparation method according to claim 6, wherein The mixing of the second mixture and the second phenolic resin to obtain a third mixture comprises: The second mixture and the second portion of phenolic resin are mixed, heated to 110-130° C., stirred at this temperature for 20-40 minutes, and then heated to 170-200° C., stirred at this temperature for 20-40 minutes to obtain a third mixture.

10. Use of the anhydrous taphole clay according to any one of claims 1 to 5 in a blast furnace taphole.

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