Energy-saving composite lining for torpedo car and preparation process of energy-saving composite lining

Abstract

The invention relates to an energy-saving composite lining for a torpedo car and a preparation process of the energy-saving composite lining, and belongs to the technical field of energy conservation and environmental protection in the iron and steel industry. The composite lining is composed of a heat preservation material layer and a high-strength low-heat-conduction refractory castable layer from inside to outside in sequence, and the heat preservation material layer and the refractory castable layer are compounded through pouring. The high-strength low-heat-conductivity refractory castable layer is prepared from the following raw materials in parts by mass: 5 to 10 parts of aluminum oxide hollow spheres, 25 to 35 parts of light mullite aggregate, 15 to 20 parts of ceramic microbeads, 5 to 10 parts of modified aluminum oxide powder, 2 to 5 parts of silica fume, 5 to 10 parts of cement and 0.1 to 1 part of additive. The prepared composite lining can reduce heat loss in the transportation process of the torpedo car and reduce the temperature reduction speed of molten iron.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and environmental protection technology in the steel industry, and relates to an energy-saving composite lining for mixed iron vehicles and its preparation process. Background Technology

[0002] The transportation and pretreatment of molten iron between the blast furnace and converter is crucial, involving multiple stages including tapping, transportation, and pretreatment. Due to its large capacity and good insulation, the molten iron mixing car has become the mainstream equipment for molten iron transportation in steel enterprises. During transportation, the molten iron needs to undergo processes such as receiving iron, slag removal, pretreatment, waiting, and unloading. Although the insulation effect of the molten iron mixing car is better than that of ordinary molten iron ladles, long-distance transportation and the "three-stage" treatment still lead to a significant drop in molten iron temperature. Excessive temperature drop can cause crusting and nodule formation on the lining of the molten iron mixing car, increasing ironmaking energy consumption, reducing metal yield, and simultaneously causing the outer shell temperature to rise, exacerbating structural thermal fatigue, threatening transportation safety, and potentially affecting production scheduling and equipment lifespan.

[0003] Currently, scrap steel is added to molten iron cars and ladles to reduce the iron-to-metal ratio and energy consumption per ton of steel. However, the addition of scrap steel further exacerbates the temperature drop of the molten iron. Heat loss in molten iron cars mainly occurs through radiation from the taphole and conduction from the outer shell. Heat loss from the taphole can be suppressed by adding a cover, while heat loss from the outer shell depends primarily on the thermal conductivity of the lining material and the thickness of the structure. Since the working layer material is difficult to change due to process limitations, and the lining thickness is also constrained by capacity, optimizing the lining structure and selecting high-performance permanent layer materials have become key technological directions for reducing heat loss, lowering temperature drop, and promoting green steelmaking.

[0004] Currently, the hybrid steel car lining structure in the industry mainly exists in the following three forms, all of which have certain shortcomings: (1) Structure without insulation layer: usually a combination of ASC bricks + high alumina coating + clay / wax stone bricks. This type of structure lacks an effective insulation layer, and the outer shell temperature is generally between 270~340℃, resulting in large heat dissipation and significant temperature drop of molten iron.

[0005] (2) The insulation layer is located between the steel shell and the permanent layer: Specific forms include pasting asbestos boards, magnesium silicate boards, fiberboards, or composite reflective insulation boards on the inner wall of the shell, or spraying nano-insulation coatings (as shown in patents CN206326120U, CN111116181A, etc.). In this type of structure, the insulation material often has low strength and poor water resistance. During use, it is easy to cause structural damage and insulation failure due to factors such as water absorption and thermal pressure. In severe cases, the shrinkage of the insulation layer may cause the permanent layer to detach from the working layer, posing a safety hazard.

[0006] (3) Change the material of the working layer to increase thermal resistance: For example, use lightweight spray patch material to replace permanent layer bricks (such as patent CN200988099Y). Although this method can reduce the thermal conductivity to a certain extent, the increase in thermal resistance is limited, the heat preservation effect is not obvious, and the spray patch construction will lead to high moisture content in the lining, increased baking energy consumption, and water vapor intrusion may also affect the service life of the lining.

[0007] Therefore, in view of the shortcomings of the existing technology, there is an urgent need to provide an energy-saving lining material and structure for hybrid steel vehicles. Summary of the Invention

[0008] The purpose of this invention is to provide an energy-saving composite lining for molten iron transport vehicles and its preparation process, which can solve the problem of heat loss from the ladle to the surrounding environment through convection and radiation during the transport of molten iron, thereby reducing the temperature drop of the molten iron.

[0009] The objective of this invention can be achieved through the following technical solutions: A composite lining for mixed iron vehicles, wherein the composite lining consists of an insulation material layer and a high-strength, low-thermal-conductivity refractory castable layer from the inside out, and is composited by casting. The high-strength, low-thermal-conductivity refractory castable layer comprises the following raw materials in parts by weight: 5-10 parts of hollow alumina spheres 25-35 parts of lightweight mullite aggregate 15-20 parts of ceramic microbeads 5-10 parts of modified alumina powder 2-5 parts silica fume 5-10 parts cement Additive 0.1~1 part The preparation process of the modified alumina powder is as follows: Alumina was dispersed in a mixed solvent of ethanol and water in a volume ratio of 9:1. 5-8% of the alumina mass of γ-aminopropyltriethoxysilane was added, and the mixture was refluxed at 70°C for 4 hours. After centrifugation, washing with ethanol, and drying, product A was obtained. Product A was dispersed in an ethanol-water solution of tetraisopropyl titanate with a concentration of 0.05~0.2 mol / L, stirred for 30 min at 0~5℃ under nitrogen protection, filtered and dried to obtain product B; Product B was immersed in a 0.1-0.5 mol / L ammonium dihydrogen phosphate aqueous solution, and the pH was adjusted to 4.0-5.0 with dilute ammonia or dilute phosphoric acid. The mixture was stirred at 60°C for 2 hours. After the stirring was completed, the product was centrifuged, washed, and dried to obtain the modified alumina powder.

[0010] As a preferred embodiment of the present invention, the particle size of the hollow alumina spheres is 1~3mm.

[0011] As a preferred embodiment of the present invention, the particle size of the lightweight mullite aggregate is 1~5mm.

[0012] As a preferred embodiment of the present invention, the ceramic microspheres have a particle size of 80 mesh.

[0013] As a preferred embodiment of the present invention, the thermal insulation material layer is one of the following: nanoporous thermal insulation material, composite reflective thermal insulation board, magnesium silicate board, and ceramic fiber board.

[0014] As a preferred embodiment of the present invention, the thickness of the thermal insulation material layer is 5~20mm, preferably 10mm.

[0015] As a preferred embodiment of the present invention, the additive is one or more of water-reducing agents, retarders, and hardening accelerators.

[0016] As a preferred embodiment of the present invention, the ratio of alumina to mixed solvent is 1 g: 30 mL.

[0017] A manufacturing process for an energy-saving composite liner for automobiles made of mixed iron and steel is as follows: S1. Mixing the castable refractory: According to the mass fractions, put the alumina hollow spheres, lightweight mullite aggregate, ceramic microspheres, modified alumina powder, silica fume, cement and additives into the equipment and mix for 5-10 minutes until uniform before pouring. S2, Pouring: Pour the mixed material into the mold, control the pouring height to the middle position of the mold, use a fixing device to fix the insulation material on the surface of the cast material, and then pour it a second time to the specified thickness, so that the cast material and the insulation material are combined. S3, Curing and Baking: The cast composite was subjected to 24 hours of natural curing and 450°C baking treatment to obtain the energy-saving composite lining.

[0018] As a preferred embodiment of the present invention, the length and width of the insulation material layer are 5-20 mm smaller than the size of the composite precast brick, preferably 10 mm.

[0019] This invention utilizes three lightweight aggregates: hollow alumina spheres, lightweight mullite aggregate, and ceramic microspheres. Hollow alumina spheres are a classic high-temperature lightweight aggregate, mullite offers good thermal stability, and ceramic microspheres fill voids to reduce density. This ternary composite aggregate design ensures sufficient strength while minimizing thermal conductivity through a multi-scale porous structure. The powder component comprises modified alumina powder, silica fume, and cement. Silica fume fills the micropores and participates in hydration, while cement provides room-temperature strength.

[0020] To improve the high-temperature strength of refractory materials, fine powders (such as α-Al₂O₃ micro powder) are usually added directly, or chemical binders such as phosphates are added externally. The former mainly relies on physical filling and high-temperature solid-state sintering, while the latter may introduce impurities or affect workability. This invention modifies alumina powder to construct a stable and robust chemical anchoring structure on the surface of the alumina powder. It pre-fixes the chemical binders (such as phosphates) that are usually added externally to the powder surface through chemical bonding, allowing it to form a reinforcing phase in situ at high temperatures. This is more uniform and efficient than directly adding phosphate powder, and it does not prematurely affect solidification, thus effectively resisting molten iron erosion and thermal stress, while maintaining excellent workability and a low thermal conductivity.

[0021] This invention first performs a silanization treatment on alumina powder. Tetraisopropyl titanate hydrolyzes on the surface of product A, forming a TiO2 coating. This coating can delay the erosion and penetration of harmful components (such as FeO and CaO) from molten iron or slag into the alumina powder. Simultaneously, it provides a reaction substrate for the third step of phosphate treatment, making subsequent treatment more uniform and robust. These phosphate groups anchored on the powder surface possess the ability to interact with other cations (such as CaO) during the preparation and service of the castable. 2+ Al 3+ The active sites that react with the reaction (etc.) allow the reinforcing phase to form in situ at high temperatures.

[0022] Therefore, modified alumina powder, through surface chemical action, requires only a small amount (5-10 parts) to generate strong bonding forces at key particle interfaces, thereby effectively improving overall strength without excessively increasing matrix density or significantly altering the overall pore structure (i.e., without sacrificing thermal insulation). When filled between lightweight aggregates, modified alumina powder not only does not damage the original thermal insulation framework but also optimizes the continuity and effectiveness of the micro-insulation network.

[0023] To improve the high-temperature strength of traditional refractory castables, it is often necessary to increase the amount of cement or add ultrafine powder, but this will increase the thermal conductivity. The formulation used in this invention introduces a large number of high-temperature bonding points at the microscale through alumina powder, thus improving high-temperature performance. At the same time, because it is a powder rather than an aggregate, its impact on the overall density and thermal conductivity is relatively small.

[0024] The beneficial effects of this invention are: This invention utilizes a low thermal conductivity refractory castable, which reduces the hot-face temperature of the insulation material, increases the thickness of the insulation material, and improves the insulation effect of the lining. This structural design protects the insulation material from pressure and moisture, extending its service life and insulation performance. This integrated composite lining structure reduces heat loss during the transport of molten iron, slows the temperature drop of the molten iron, reduces energy consumption in subsequent smelting processes, lowers the iron-to-metal ratio, improves efficiency, and is more environmentally friendly. Attached Figure Description

[0025] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 This is a schematic diagram of the structure of the composite liner prepared according to the present invention; Figure 2 This is a schematic cross-sectional view of the composite lining structure prepared according to the present invention. Detailed Implementation

[0027] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0028] It should be noted that, unless otherwise specified, the present invention does not specifically limit the source of the raw materials used in the following embodiments. Commercially available products or products prepared by conventional preparation methods that are well known to those skilled in the art can be used. Experimental methods that do not specify specific conditions are all conventional methods and conventional conditions well known in the art.

[0029] The preparation process of the composite liner in the following examples and comparative examples is as follows: S1. Mixing the castable refractory: According to the mass fractions, put the alumina hollow spheres, lightweight mullite aggregate, ceramic microspheres, modified alumina powder, silica fume, cement and additives into the equipment and mix for 10 minutes. After uniform mixing, it is ready for pouring. S2, Pouring: Pour the mixed material into the mold, control the pouring height to the middle position of the mold, use a fixing device to fix the insulation material on the surface of the cast material, and then pour it a second time to the specified thickness, so that the cast material and the insulation material are combined. S3, Curing and Baking: The cast composite was subjected to 24 hours of natural curing and 450℃ baking treatment to obtain an energy-saving composite lining.

[0030] Example 1 The high-strength, low-thermal-conductivity refractory castable layer comprises the following raw materials in parts by weight: 10 parts of hollow alumina spheres 35 parts of lightweight mullite aggregate 20 portions of ceramic microbeads 10 parts of modified alumina powder 5 parts silica fume 10 parts cement 1 part of additive The preparation process of the modified alumina powder is as follows: Alumina was dispersed in a mixed solvent of ethanol and water in a volume ratio of 9:1. γ-aminopropyltriethoxysilane (7% by mass of alumina) was added, and the mixture was refluxed at 70°C for 4 h. After centrifugation, washing with ethanol, and drying, product A was obtained. The ratio of alumina to the mixed solvent was 1 g: 30 mL. Product A was dispersed in an ethanol-water solution of tetraisopropyl titanate at a concentration of 0.1 mol / L, stirred for 30 min at 0 °C under nitrogen protection, filtered and dried to obtain product B; Product B was immersed in a 0.4 mol / L aqueous solution of ammonium dihydrogen phosphate, and the pH was adjusted to 4.0-5.0 with dilute ammonia or dilute phosphoric acid. The mixture was stirred at 60°C for 2 hours. After the stirring was completed, the product was centrifuged, washed, and dried to obtain the modified alumina powder.

[0031] In this embodiment, the insulation material is a nanoporous thermal insulation material with a thickness of 10mm. The length and width of the insulation material layer are 10mm smaller than the dimensions of the composite lining.

[0032] The performance of the high-strength, low-thermal-conductivity refractory castable layer of Example 1 was tested, and the results are shown in Table 1 below: Table 1

[0033] Example 2 The high-strength, low-thermal-conductivity refractory castable layer comprises the following raw materials in parts by weight: 5 parts of hollow alumina spheres 25 parts of lightweight mullite aggregate 15 portions of ceramic microbeads 5 parts of modified alumina powder 2 parts silica fume 8 parts cement 0.5 parts of additive The preparation process of the modified alumina powder is as follows: Alumina was dispersed in a mixed solvent of ethanol and water in a volume ratio of 9:1. γ-aminopropyltriethoxysilane (8% by mass of alumina) was added, and the mixture was refluxed at 70°C for 4 hours. After centrifugation, washing with ethanol, and drying, product A was obtained. The ratio of alumina to the mixed solvent was 1 g: 30 mL. Product A was dispersed in an ethanol-water solution of 0.2 mol / L tetraisopropyl titanate, stirred for 30 min at 5 °C under nitrogen protection, filtered and dried to obtain product B; Product B was immersed in a 0.5 mol / L ammonium dihydrogen phosphate aqueous solution, and the pH was adjusted to 4.0-5.0 with dilute ammonia or dilute phosphoric acid. The mixture was stirred at 60°C for 2 hours. After the stirring was completed, the product was centrifuged, washed, and dried to obtain the modified alumina powder.

[0034] In this embodiment, the insulation material is ceramic fiber material, the insulation material layer thickness is 18mm, and the length and width of the insulation material layer are 8mm smaller than the dimensions of the composite lining.

[0035] The performance of the high-strength, low-thermal-conductivity refractory castable layer in Example 2 was tested, and the results are shown in Table 2 below: Table 2

[0036] Comparative Example 1 This is basically the same as Example 1, except that the alumina powder in this comparative example has not undergone modification treatment.

[0037] Comparative Example 2 This is basically the same as Example 1, except that this comparative example uses alumina powder that has only been modified with a silane coupling agent.

[0038] Comparative Example 3 This is basically the same as Example 1, except that in this comparative example, ordinary alumina powder, nano titanium dioxide powder, and ammonium dihydrogen phosphate powder are simply mechanically mixed to replace the modified alumina powder.

[0039] The performance of the high-strength, low-thermal-conductivity refractory castable layers in Examples 1 and Comparative Examples 1-3 was tested. The results showed that the compressive strength at 400℃ / MPa (GB / T 3001) was 48.5MPa, 32.0MPa, 40.2MPa, and 37.8MPa, respectively. At the same time, according to the simulated molten iron temperature drop test (molten iron at 1500℃, held for 1 hour), the temperature drop of the molten iron in the mixing car in Examples 1 and 2 was significantly reduced. The temperature drop in Example 1 was reduced by 49℃ compared to the original structure, and the outer shell temperature was more than 92℃ lower. The temperature drop in Example 2 was reduced by 37℃ compared to the original structure, and the outer shell temperature was more than 74℃ lower.

[0040] Therefore, based on the above data, it can be seen that the overall composite lining structure prepared by the present invention can reduce heat loss during the transportation of molten iron and reduce the rate of temperature drop of molten iron.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A composite lining for hybrid steel vehicles, characterized in that, The composite lining consists of an insulation material layer and a high-strength, low-thermal-conductivity refractory castable layer from the inside out, and is composited by casting. The high-strength, low-thermal-conductivity refractory castable layer comprises the following raw materials in parts by weight: 5-10 parts of hollow alumina spheres 25-35 parts of lightweight mullite aggregate 15-20 parts of ceramic microbeads 5-10 parts of modified alumina powder 2-5 parts silica fume 5-10 parts cement Additive 0.1~1 part The preparation process of the modified alumina powder is as follows: Alumina was dispersed in a mixed solvent of ethanol and water in a volume ratio of 9:

1. 5-8% of the alumina mass of γ-aminopropyltriethoxysilane was added, and the mixture was refluxed at 70°C for 4 hours. After centrifugation, washing with ethanol, and drying, product A was obtained. Product A was dispersed in an ethanol-water solution of tetraisopropyl titanate with a concentration of 0.05~0.2 mol / L, stirred for 30 min at 0~5℃ under nitrogen protection, filtered and dried to obtain product B; Product B was immersed in a 0.1-0.5 mol / L ammonium dihydrogen phosphate aqueous solution, and the pH was adjusted to 4.0-5.0 with dilute ammonia or dilute phosphoric acid. The mixture was stirred at 60°C for 2 hours. After the stirring was completed, the product was filtered, washed and dried to obtain the modified alumina powder.

2. The energy-saving composite liner for hybrid steel vehicles according to claim 1, characterized in that, The alumina hollow spheres have a particle size of 1~3mm.

3. The energy-saving composite liner for hybrid steel vehicles according to claim 1, characterized in that, The lightweight mullite aggregate has a particle size of 1~5mm.

4. The energy-saving composite liner for hybrid steel vehicles according to claim 1, characterized in that, The ceramic microspheres have a particle size of 80 mesh.

5. The energy-saving composite liner for hybrid steel vehicles according to claim 1, characterized in that, The insulation material layer is one of the following: nanoporous thermal insulation material, composite reflective insulation board, magnesium silicate board, and ceramic fiber board.

6. The energy-saving composite liner for hybrid steel vehicles according to claim 1, characterized in that, The thickness of the insulation material layer is 5~20mm, preferably 10mm.

7. The energy-saving composite liner for hybrid steel vehicles according to claim 1, characterized in that, The additive is one or more of the following: water-reducing agent, retarder, and hardening agent.

8. The energy-saving composite liner for hybrid steel vehicles according to claim 1, characterized in that, The ratio of alumina to the mixed solvent is 1 g: 30 mL.

9. A preparation process for a composite lining for automobiles made of mixed iron as described in any one of claims 1-8, characterized in that, The preparation process is as follows: S1. Mixing the castable refractory: According to the mass fractions, put the alumina hollow spheres, lightweight mullite aggregate, ceramic microspheres, modified alumina powder, silica fume, cement and additives into the equipment and mix for 5-10 minutes until uniform before pouring. S2, Pouring: Pour the mixed material into the mold, control the pouring height to the middle position of the mold, use a fixing device to fix the insulation material on the surface of the cast material, and then pour it a second time to the specified thickness, so that the cast material and the insulation material are combined. S3, Curing and Baking: The cast composite was subjected to 24 hours of natural curing and 450°C baking treatment to obtain the energy-saving composite lining.

10. The energy-saving composite liner for hybrid steel vehicles according to claim 9, characterized in that, The length and width of the insulation material layer are 5-20 mm smaller than the dimensions of the composite precast bricks, preferably 10 mm.

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