A method for preparing ceramic-based porous thermal insulation materials based on waste hot slag and its application

Abstract

This invention relates to the field of porous ceramic preparation technology, specifically to a method for preparing ceramic-based porous insulation materials based on waste hot slag and its application. Addressing the problems of high energy consumption and low production efficiency in the firing of ceramic-based porous insulation materials, this method directly utilizes waste hot slag discharged from smelters. By adding auxiliary raw materials for conditioning and homogenization, and then using a powder sprayer and pipeline mixer to uniformly mix foaming agent powder with the slag, the mixture is poured into refractory molds. After static foaming, annealing and cooling, demolding, and cutting in an annealing kiln, a well-shaped ceramic-based porous insulation material is finally produced. This method of directly preparing ceramic-based porous insulation materials using waste hot slag fully utilizes the thermal energy and minerals of the waste hot slag, achieving energy-saving and material-saving production of ceramic-based porous insulation materials, improving the production efficiency of porous ceramics, and promoting the high-value-added utilization of hot-melt industrial waste.

Description

Technical Field

[0001] This invention relates to the field of porous ceramic preparation technology, specifically to a method for preparing ceramic-based porous thermal insulation materials based on waste hot slag and its application. Background Technology

[0002] With the continuous advancement of industrialization, the rapid development of the metallurgical industry has led to a year-on-year increase in the output of industrial metallurgical slag. Statistics show that the production of each ton of steel generates approximately 300-400 kg of hot slag, with annual hot slag production from metal smelting alone reaching as high as 200 million tons. However, the comprehensive utilization rate of hot slag is currently low, with low added value. Most of it is simply piled up or landfilled, not only occupying a large amount of land resources but also potentially causing secondary pollution to the environment. Furthermore, the discharge of hot slag is usually accompanied by the release of a large amount of sensible heat at high temperatures (1300-1500 °C), but current technologies are severely inadequate in recovering and utilizing this calorific value.

[0003] Ceramic-based porous insulation materials are lightweight, high-strength functional materials widely used in construction, chemical, and aerospace fields due to their excellent high-temperature resistance, thermal insulation, sound insulation, and corrosion resistance. Currently, closed-cell foamed ceramic insulation materials are widely used in building insulation and decoration. To reduce material preparation costs, the large-scale use of industrial solid waste has become a major direction in the preparation of foamed ceramics. For example, Chinese invention patent CN201080037709.9 discloses a method for preparing porous ceramics using electrolytic manganese slag. This method uses manganese slag as aggregate, adds pore-forming agents, binders, fluxes, etc., and prepares porous ceramics through solid-state sintering at 1070~1180℃. Although utilizing industrial solid waste effectively reduces the raw material cost of porous ceramics, traditional preparation processes require room-temperature grinding and powdering, followed by high-temperature sintering and foaming, with firing temperatures exceeding 1000 °C. The process is complex and energy-intensive, resulting in high unit product manufacturing costs.

[0004] Industrial solid waste generated from smelting metals by melting has also become a major raw material for porous ceramic insulation materials. For example, Chinese invention patent CN 201910975280.0 discloses a method for preparing foamed ceramics using water-quenched nickel-iron slag. This method involves mixing and grinding water-quenched nickel-iron slag with other auxiliary raw materials to form a slurry, then drying and molding it, followed by high-temperature firing at 1120-1165℃ in a kiln to produce foamed ceramics. This method fully utilizes the aluminum and silicon components in the nickel-iron slag, effectively reducing the amount of mineral raw materials used in foamed ceramics. However, as a high-temperature molten nickel-iron slag, it requires water quenching followed by ball milling, drying, and calcination, resulting in wasted thermal energy. Furthermore, while Chinese invention patent application CN201811600692.8 discloses a method and apparatus for preparing porous glass-ceramic basic raw materials and porous glass-ceramics using hot molten slag after hazardous waste treatment, the process still involves water quenching followed by firing, resulting in high energy consumption and difficulty in improving production efficiency.

[0005] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of reducing the material preparation cost and using large amounts of industrial solid waste when preparing foamed ceramics. It provides a method for preparing ceramic-based porous thermal insulation materials based on waste hot slag and its application.

[0007] To achieve the above objectives, this invention discloses a method for preparing ceramic-based porous thermal insulation materials based on waste hot slag, comprising the following steps:

[0008] S1, the waste hot slag discharged from the smelting furnace is introduced into the slag conditioning furnace through the slag trough, and auxiliary raw materials are added through the feeding port of the slag conditioning furnace. The furnace is then heated, kept warm, and homogenized to keep the hot slag in a flowing state, thus obtaining the conditioned hot slag.

[0009] S2, the quenched hot slag is discharged from the bottom slit outlet of the slag quenching furnace, and the foaming agent is sprayed onto the surface of the molten slag using a powder sprayer; under the action of gravity, the molten slag flows through the pipe mixer, so that the foaming agent and the molten slag flow are evenly mixed.

[0010] S3, the molten slag flowing out of the pipe mixer enters the annealing furnace and is poured into the refractory mold inside the annealing furnace;

[0011] S4. After casting, the product is left to stand in the annealing furnace for foaming, annealing and cooling, demolding and cutting, and finally made into a regular-shaped ceramic-based porous insulation material.

[0012] In step S1, the waste hot slag is a high-temperature liquid slag discharged during the metal smelting process, including but not limited to steel slag, ore slag, ferromanganese alloy slag, and ferronickel alloy slag, with a temperature ≥1300℃. The chemical composition of the waste hot slag by mass percentage includes: SiO2 30%~60%, Al2O3 10%~40%, Fe2O3 0.5%~15%.

[0013] In step S1, the auxiliary raw material is aluminum-silica mineral or industrial solid waste, and the moisture content of the auxiliary raw material is ≤2% and the particle size is ≤80μm.

[0014] In step S1, the chemical composition of the conditioned hot slag by mass percentage includes: SiO2 40%~70%, Al2O3 10%~30%, Fe2O3 0~5%, CaO 5%~18%, MgO≤10%, K2O+Na2O 3%~12%.

[0015] In step S1, the heat preservation and homogenization temperature is 1300~1600℃, and the heat preservation time is 0.5~3h.

[0016] The foaming agent includes silicon carbide, silicon nitride, calcium carbonate, and graphite powder, with a powder particle size ≤13μm, and the amount used accounts for 0.1%-3% of the weight of the hot molten slag.

[0017] In step S4, the static foaming, annealing and cooling are as follows: keep at 1150~1320℃ for 0.5~2h, then cool down to 850~1000℃ at -5~-15℃ / min, keep at 850~1000℃ for 10~60min, and then cool down to room temperature at -2~-8℃ / min.

[0018] In step S4, the obtained ceramic-based porous insulation material has a pore size of 0.5~3.5mm, a porosity of 50%~85%, a thermal conductivity of 0.08~0.32W / (m·K), a compressive strength of 1~25 MPa, and a volume water absorption rate of 0.5%~5%.

[0019] The present invention also discloses a ceramic-based porous thermal insulation material based on waste hot slag prepared by the above preparation method, and the application of such a ceramic-based porous thermal insulation material based on waste hot slag in the construction of building walls.

[0020] This invention proposes a method for preparing ceramic-based porous insulation materials based on waste hot molten slag. The method involves conditioning the high-temperature hot molten slag, mixing it with foaming agent powder while maintaining its hot molten state, casting, allowing it to foam, and finally annealing and cooling to obtain a ceramic-based porous insulation material with excellent mechanical properties. In achieving this technical solution, controlling the composition of the hot molten slag and achieving uniform mixing of the foaming agent and the hot molten slag is crucial for preparing a ceramic-based porous insulation material with a uniform pore structure. To this end, this invention proposes using aluminosilicate minerals or industrial solid waste as auxiliary raw materials and utilizing a slag conditioning furnace to homogenize the components, thereby obtaining a suitable foaming viscosity state for the hot molten slag. Furthermore, to achieve efficient and uniform mixing of the foaming agent and the high-temperature melt, this invention sets a discharge slit, allowing the conditioned high-temperature liquid molten slag to be discharged in a "waterfall" manner. Then, a powder sprayer is used to spray the foaming agent onto the surface of the molten slag flow, initially achieving a uniform distribution of the foaming agent powder within the molten slag. Subsequently, using an SK-type static liquid mixing tube made of silicon carbide, the molten slag containing the foaming agent was spontaneously mixed a second time under gravity, ensuring the uniform dispersion of the foaming agent within the molten slag. Since there was no dynamic mixing device during the entire mixing process, continuous and stable operation of the equipment at high temperatures was guaranteed.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. This invention proposes a method for directly preparing porous ceramic insulation materials using waste hot slag. Only additional auxiliary raw materials and heat are needed to obtain high-temperature hot-melt blanks. Then, foaming agents are mixed with hot-melt blanks through a powder spraying machine and a pipeline mixer. Samples of different sizes can be formed by casting. The process is simple and efficient, which greatly reduces the energy consumption in the preparation of porous foamed ceramics and lowers the production cost of materials.

[0023] 2. This invention proposes an innovative process for the efficient utilization of the "heat and mass" resources of waste hot slag. It directly uses hot waste slag as the main raw material, realizing the efficient synergistic utilization of the "heat and mass" of hot slag, and providing a new direction for the high-value-added utilization of solid waste in the metallurgical industry.

[0024] 3. The porous ceramic insulation material prepared by this invention has a large number of closed pores, high porosity, and good thermal insulation performance. Furthermore, the porosity of the material can be arbitrarily adjusted by controlling the amount of foaming agent. Simultaneously, the material exhibits zero shrinkage, is waterproof, corrosion-resistant, and has high strength. When used to construct building walls, it not only significantly improves the thermal insulation performance of the walls and reduces their weight, but also ensures high dimensional stability. Attached Figure Description

[0025] Figure 1 This is a process flow diagram used in this invention;

[0026] Figure 2This is a diagram showing the external appearance and internal structure of the SK-type static pipe mixer used in this invention;

[0027] Figure 3 The image shows the pore structure morphology of the ceramic-based porous lightweight thermal insulation material prepared in Example 1 of this invention.

[0028] The numbers in the image represent:

[0029] 1-Connecting flange; 2-Silicon carbide tube shell; 3-Left-handed unit piece; 4-Right-handed unit piece. Detailed Implementation

[0030] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0031] The chemical composition of the hot-melt slag in Examples 1-5 is shown in Table 1 below:

[0032] Table 1 Chemical composition of hot-melt slag in Examples 1-5

[0033]

[0034] Example 1

[0035] Reference Figure 1 The production process involves introducing the hot molten slag discharged during blast furnace ironmaking into a slag tempering furnace via a slag trough. The chemical composition of the hot molten slag is shown in Table 1. The tempering furnace uses a corundum crucible as a container, with a feed inlet at the top and a 10 mm wide discharge slit at the bottom. The furnace temperature is controlled at 1500 ℃. Auxiliary raw materials, consisting of fly ash and lithium tailings, are added through the furnace feed inlet at a ratio of 4 parts hot molten slag, 4 parts fly ash, and 2 parts lithium tailings. The furnace is then held at 1500 ℃ for 1.5 hours to homogenize. The chemical composition of the hot molten slag after tempering is shown in Table 2.

[0036] Table 2 Chemical composition of the quenched and tempered hot slag in Example 1

[0037]

[0038] The quenched and tempered hot slag is discharged from the narrow outlet at the bottom of the quenching and tempering furnace. A powder sprayer is placed on the side of the molten slag flow, perpendicular to it, and sprays foaming agent powder evenly onto the surface of the flow. The foaming agent is silicon carbide micropowder with a median particle size of 9.7 μm, and the spraying amount is 2.5% of the molten slag mass. Under the influence of gravity, the molten slag flows through an SK-type static pipe mixer. Inside the mixer, multiple sets of forward and reverse spiral units cause the high-temperature molten slag to undergo three processes: diversion, cross-mixing, and reverse swirling. This allows the foaming agent powder to be rapidly and evenly dispersed throughout the melt, ensuring a uniform mixture between the foaming agent and the molten slag.

[0039] SK type static pipe mixer, such as Figure 2 As shown, the SK-type static liquid mixer is connected to the slit outlet at the bottom of the tempering furnace via connecting flange 1. The SK-type static liquid mixer consists of a silicon carbide tube shell 2 and left-handed and right-handed unit plates 3 and 4, twisted by 180° and 270° respectively. When the molten slag passes through the mixing tube, it generates three effects: diversion, cross-mixing, and reverse swirling, allowing the added foaming agent powder to be rapidly and uniformly dispersed throughout the melt, achieving instantaneous mixing. Its structure is the same as the traditional SK-type static liquid mixing tube, but to ensure continuous operation at high temperatures, all its components are made of SiC material.

[0040] The uniformly mixed molten slag flows into a roller annealing furnace and is poured into a high-alumina refractory mold on the rollers. The furnace temperature is controlled at 1220 ℃. After pouring, the molten slag undergoes foaming, annealing, and cooling within the furnace according to the following firing regime:

[0041] (1) Keep warm at 1220℃ for 40 minutes;

[0042] (2) Cool down to 950℃ at -10℃ / min and keep warm for 30 minutes;

[0043] (3) Cool down to room temperature at -2℃ / min.

[0044] The cooled product was removed from the mold and processed into regularly shaped porous ceramic insulation materials using a cutting device. The performance parameters of the prepared ceramic-based porous insulation materials are shown in Table 7. The pore structure morphology of the prepared samples is shown in... Figure 3 As shown, by Figure 3 It can be seen that the ceramic-based porous insulation material prepared by this method has a large number of closed pores with a pore size of about 1.1~1.6mm. The pore walls are relatively thin but intact, and the closed porosity is high. Example

[0045] Reference Figure 1 The production process involves introducing the hot molten slag discharged during blast furnace ironmaking into a slag tempering furnace via a slag trough. The chemical composition of the hot molten slag is shown in Table 1. The tempering furnace uses a corundum crucible as a container, with a feed inlet at the top and a 10 mm wide discharge slit at the bottom. The furnace temperature is controlled at 1400 ℃. Auxiliary raw materials, consisting of fly ash and lithium tailings, are added through the furnace feed inlet at a ratio of 4 parts hot molten slag, 3 parts fly ash, and 3 parts lithium tailings. The furnace is then held at 1450 ℃ for 1.5 hours to homogenize. The chemical composition of the hot molten slag after tempering is shown in Table 3.

[0046] Table 3 Chemical composition of the quenched and tempered hot slag in Example 2

[0047]

[0048] After the molten slag is discharged from the bottom of the tempering furnace, silicon carbide foaming agent (particle size 9.7μm, added at 1.8% of the molten slag mass) is sprayed onto the flowing molten slag using a powder sprayer. Under gravity, the molten slag flows through an SK-type static pipe mixer. Inside the mixer, multiple sets of forward and reverse spiral units cause the liquid high-temperature molten slag to undergo three processes: diversion, cross-mixing, and reverse swirling. This allows the foaming agent powder to be rapidly and evenly dispersed throughout the melt, ensuring a uniform mixture between the foaming agent and the molten slag. The uniformly mixed molten slag then enters a roller annealing furnace and is poured into a high-alumina refractory mold on the roller. The furnace temperature is controlled at 1250℃, and the firing process is completed according to the following schedule:

[0049] 1. Keep warm at 1250℃ for 50 minutes;

[0050] 2. Cool to 980℃ at a rate of -7℃ / min and hold for 40 minutes;

[0051] 3. Cool down to room temperature at a rate of -2 ℃ / min.

[0052] After cooling, the product is removed from the mold and processed into regularly shaped porous ceramic insulation materials using a cutting device. The performance parameters of the prepared ceramic-based porous insulation materials are shown in Table 7. Example

[0053] Reference Figure 1 The production process involves introducing the hot molten slag discharged during blast furnace ironmaking into a slag tempering furnace via a slag trough. The chemical composition of the hot molten slag is shown in Table 1. The tempering furnace uses a corundum crucible as its container, with a feed inlet at the top and a 10 mm wide discharge slit at the bottom. The furnace temperature is controlled at 1400 ℃. Auxiliary raw materials, consisting of fly ash and lithium tailings, are added through the furnace feed inlet at a ratio of 4 parts hot molten slag, 1 part fly ash, and 5 parts lithium tailings. The furnace is then held at 1400 ℃ for 2 hours for homogenization. The chemical composition of the hot molten slag after tempering is shown in Table 4.

[0054] Table 4 Chemical composition of the quenched and tempered hot slag in Example 3

[0055]

[0056] The quenched and tempered hot slag is discharged from the narrow outlet at the bottom of the quenching and tempering furnace. A powder sprayer is placed on the side of the molten slag flow, perpendicular to it, and sprays foaming agent powder evenly onto the surface of the flow. The foaming agent is silicon carbide micropowder with a median particle size of 9.7 μm, and the spraying amount is 1.5% of the molten slag mass. Under gravity, the molten slag flows through an SK-type static pipe mixer. Inside the mixer, multiple sets of forward and reverse spiral units cause the high-temperature molten slag to undergo three processes: diversion, cross-mixing, and reverse swirling. This allows the foaming agent powder to be rapidly and evenly dispersed throughout the melt, ensuring uniform mixing between the foaming agent and the molten slag.

[0057] The uniformly mixed molten slag flows into a roller annealing furnace and is poured into a high-alumina refractory mold on the rollers. The furnace temperature is controlled at 1220 ℃. After pouring, the molten slag undergoes foaming, annealing, and cooling within the furnace according to the following firing regime:

[0058] (1) Keep warm at 1220℃ for 40 minutes;

[0059] (2) Cool down to 950℃ at -10℃ / min and keep warm for 30 minutes;

[0060] (3) Cool down to room temperature at -2℃ / min.

[0061] After cooling, the product is removed from the mold and processed into regularly shaped porous ceramic insulation materials using a cutting device. The performance parameters of the finished ceramic-based porous insulation materials are shown in Table 7. Example

[0062] Reference Figure 1 The production process involves introducing the high-temperature molten slag discharged during the smelting of ferromanganese alloys into a slag quenching furnace via a slag channel. The chemical composition of the ferromanganese alloy slag is shown in Table 1. The quenching furnace uses a corundum crucible as a container, with a feed inlet at the top and a 10 mm wide discharge slit at the bottom. The furnace temperature is controlled at 1500 ℃.

[0063] Auxiliary raw materials, namely metakaolin, were added through the charging port of the quenching furnace at a ratio of 5 parts manganese-ferromanganese alloy slag and 5 parts metakaolin. The furnace was then heated at 1500 ℃ for 2 hours to homogenize. The chemical composition of the quenched manganese-ferromanganese alloy slag is shown in Table 5 below.

[0064] Table 5 Chemical composition of the quenched and tempered manganese-ferroalloy slag in Example 4

[0065]

[0066] The quenched and tempered high-temperature slag is discharged from the narrow outlet at the bottom of the quenching and tempering furnace, and a foaming agent is sprayed into the liquid slag stream using a powder sprayer. The foaming agent is silicon nitride micro powder with a median particle size of 8.5 μm, and the spraying amount is 1.0% of the slag mass. Under the action of gravity, the molten slag flows through an SK-type static pipe mixer. Under the action of multiple sets of forward and reverse spiral units inside the mixer, the liquid high-temperature slag undergoes three effects: diversion, cross-mixing, and reverse swirling, which rapidly and uniformly disperses the foaming agent powder throughout the melt. The slag mixed with the foaming agent enters the annealing furnace and is cast into a high-alumina refractory mold on a roller conveyor. The furnace temperature is controlled at 1300 ℃, and foaming, annealing, and cooling are completed according to the following firing regime:

[0067] (1) Keep warm at 1300 ℃ for 30 minutes;

[0068] (2) Cool down to 950 ℃ at -8 ℃ / min and hold for 20 minutes;

[0069] (3) Cool down to room temperature at -5 ℃ / min.

[0070] After cooling, the product is removed from the mold and processed into regularly shaped porous ceramic insulation materials using a cutting device. The performance parameters of the finished ceramic-based porous insulation materials are shown in Table 7. Example

[0071] Reference Figure 1 The production process involves introducing the high-temperature molten slag discharged during the smelting of ferromanganese alloys into a slag quenching furnace via a slag channel. The chemical composition of the ferromanganese alloy slag is shown in Table 1. The quenching furnace uses a corundum crucible as a container, with a feed inlet at the top and a 10 mm wide discharge slit at the bottom. The furnace temperature is controlled at 1450 ℃.

[0072] Auxiliary raw materials, consisting of metakaolin and lithium tailings, were added through the charging port of the quenching furnace at a ratio of 5 parts manganese-ferromanganese alloy slag, 4 parts metakaolin, and 1 part lithium tailings. The furnace was then held at 1450 ℃ for 1.5 hours to homogenize. The chemical composition of the quenched manganese-ferromanganese alloy slag is shown in Table 6 below.

[0073] Table 6 Chemical composition of the quenched and tempered manganese-ferroalloy slag in Example 5

[0074]

[0075] The quenched and tempered high-temperature slag is discharged from the narrow outlet at the bottom of the quenching and tempering furnace, and a foaming agent is sprayed into the liquid slag stream using a powder sprayer. The foaming agent is silicon nitride micro powder with a median particle size of 8.5 μm, and the spraying amount is 1.6% of the slag mass. Under the action of gravity, the molten slag flows through an SK-type static pipe mixer. Under the action of multiple sets of forward and reverse spiral units inside the mixer, the liquid high-temperature slag undergoes three effects: diversion, cross-mixing, and reverse swirling, which rapidly and uniformly disperses the foaming agent powder throughout the melt. The slag mixed with the foaming agent enters the annealing furnace and is cast into a high-alumina refractory mold on a roller conveyor. The furnace temperature is controlled at 1200 ℃, and foaming, annealing, and cooling are completed according to the following firing regime:

[0076] (1) Keep warm at 1260 ℃ for 50 minutes;

[0077] (2) Cool down to 900 ℃ at -5 ℃ / min and hold for 40 minutes;

[0078] (3) Cool down to room temperature at -2 ℃ / min.

[0079] After cooling, the product is removed from the mold and processed into regularly shaped porous ceramic insulation materials using a cutting device. The performance parameters of the finished ceramic-based porous insulation materials are shown in Table 7.

[0080] Table 7 Performance parameters of porous ceramic insulation materials prepared in Examples 1-5

[0081]

[0082] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

[0083] Comparative Example 1:

[0084] Reference Figure 1 The production process involves introducing the high-temperature molten slag discharged during the smelting of ferromanganese alloys into a slag quenching furnace via a slag channel. The chemical composition of the ferromanganese alloy slag is shown in Table 1. The quenching furnace uses a corundum crucible as a container, with a feed inlet at the top and a discharge hole with a diameter of 5 cm at the bottom. The temperature inside the furnace is controlled at 1450 ℃.

[0085] Auxiliary raw materials were added through the charging port of the quenching furnace. The auxiliary raw materials and their proportions were the same as in Example 5, and the furnace was held at 1450 °C for 1.5 hours to homogenize. The chemical composition of the quenched ferromanganese alloy slag was the same as in Example 5.

[0086] The quenched and tempered high-temperature slag was directly discharged from the circular hole at the bottom of the quenching and tempering furnace, and a foaming agent was sprayed onto the molten slag stream using a powder sprayer. The foaming agent and spraying amount were the same as in Example 5. The molten slag stream with foaming agent powder attached was directly poured into a high-alumina refractory mold on the roller conveyor of the annealing kiln under gravity. The kiln temperature and annealing cooling process were the same as in Example 5.

[0087] After cooling, the product is removed from the mold and processed into regularly shaped porous ceramic insulation materials using a cutting device. The performance parameters of the finished ceramic-based porous insulation materials are shown in Table 9.

[0088] As can be seen from Comparative Example 5, because Comparative Example 1 did not use a slag tempering furnace with a discharge slit, the foaming agent powder could not fully contact the slag, and the slag was not subsequently passed through an SK-type pipe mixer, resulting in uneven mixing of the foaming agent and the slag. Therefore, the resulting porous ceramic material had a large pore size, but lower porosity, lower compressive strength, and increased volumetric water absorption to 10.7%. Furthermore, due to the excessively large pore size, the thermal conductivity could not be accurately measured.

[0089] Comparative Example 2:

[0090] Reference Figure 1 The production process involves introducing the hot molten slag discharged during blast furnace ironmaking into a slag tempering furnace via a slag trough. The chemical composition of the hot molten slag is shown in Table 1. The tempering furnace uses a corundum crucible as its container, with a feed inlet at the top and a 10 mm wide discharge slit at the bottom. The furnace temperature is controlled at 1400 ℃. Auxiliary raw materials, consisting of lithium tailings, are added through the furnace feed inlet at a ratio of 8 parts hot molten slag and 2 parts lithium tailings. The furnace is then held at 1400 ℃ for 2 hours for homogenization. The chemical composition of the hot molten slag after tempering is shown in Table 8.

[0091] Table 8 Chemical composition of quenched and tempered manganese-ferroalloy slag in Comparative Example 2

[0092]

[0093] The quenched and tempered high-temperature slag is discharged from the narrow outlet at the bottom of the quenching and tempering furnace, and a foaming agent is sprayed onto the molten slag stream using a powder sprayer. The foaming agent is silicon carbide micro powder, with the same particle size and dosage as in Example 3. Under gravity, the molten slag stream passes through an SK-type static pipe mixer, where it is thoroughly mixed with the foaming agent before entering the annealing furnace and being poured into a high-alumina refractory mold on a roller conveyor. The furnace temperature and cooling annealing regime are the same as in Example 3.

[0094] After cooling, the product is removed from the mold and processed into regularly shaped porous ceramic insulation materials using a cutting device. The performance parameters of the finished ceramic-based porous insulation materials are shown in Table 9.

[0095] As can be seen from Comparative Example 3, when the composition of the slag formed after the addition of auxiliary raw materials for conditioning differs from the scope of the claims, it leads to an increase in the pore size of the bubbles formed in the sample and uneven distribution. At the same time, due to the generation of a large number of open pores, the volume water absorption rate of the sample increases to 59.3%. In addition, due to the excessively large pore size, the thermal conductivity cannot be accurately measured.

[0096] Table 9 Performance parameters of the porous ceramic thermal insulation materials prepared in Comparative Examples 1 and 2

[0097]

[0098] Note: Due to the excessively large aperture size, the thermal conductivity could not be tested.

Claims

1. A method for preparing ceramic-based porous thermal insulation materials based on waste hot slag, characterized in that, Includes the following steps: S1, the waste hot slag discharged from the smelting furnace is introduced into the slag conditioning furnace through the slag trough, and auxiliary raw materials are added through the feeding port of the slag conditioning furnace. The furnace is then heated, kept warm, and homogenized to keep the hot slag in a flowing state, thus obtaining the conditioned hot slag. S2, the quenched hot slag is discharged from the bottom slit outlet of the slag quenching furnace, and the foaming agent is sprayed onto the surface of the molten slag using a powder sprayer; under the action of gravity, the molten slag flows through the pipe mixer, so that the foaming agent and the molten slag are evenly mixed. S3, the molten slag flowing out of the pipe mixer enters the annealing furnace and is poured into the refractory mold inside the annealing furnace; S4. After casting, the product is left to stand in the annealing furnace for foaming, annealing and cooling, demolding and cutting, and finally made into a regular-shaped ceramic-based porous insulation material. In step S1, the waste hot slag is a high-temperature liquid slag discharged during the metal smelting process, including steel slag, ore slag, ferromanganese alloy slag, and ferronickel alloy slag, with a temperature ≥1300℃. The chemical composition of the waste hot slag by mass percentage includes: SiO2 30%~60%, Al2O3 10%~40%, Fe2O3 0.5%~15%. In step S1, the chemical composition of the conditioned hot slag by mass percentage includes: SiO2 40%~70%, Al2O3 10%~30%, Fe2O3 0~5%, CaO 5%~18%, MgO≤10%, K2O+Na2O 3%~12%; The foaming agent includes silicon carbide, silicon nitride, calcium carbonate, and graphite powder; The pipeline mixer is an SK-type static liquid mixer. The SK-type static liquid mixer is connected to the slit outlet at the bottom of the tempering furnace via a connecting flange. The SK-type static liquid mixer consists of a silicon carbide tube shell and left-handed and right-handed unit plates twisted by 180° and 270°, respectively.

2. The method for preparing ceramic-based porous thermal insulation material based on waste hot slag as described in claim 1, characterized in that, In step S1, the auxiliary raw material is aluminum-silica mineral or industrial solid waste, and the moisture content of the auxiliary raw material is ≤2% and the particle size is ≤80μm.

3. The method for preparing ceramic-based porous thermal insulation materials based on waste hot slag as described in claim 1, characterized in that, In step S1, the heat preservation and homogenization temperature is 1300~1600℃, and the heat preservation time is 0.5~3h.

4. The method for preparing ceramic-based porous thermal insulation material based on waste hot slag as described in claim 1, characterized in that, The foaming agent has a powder particle size ≤13μm and is used in an amount of 0.1%-3% of the weight of the hot molten slag.

5. The method for preparing ceramic-based porous thermal insulation material based on waste hot slag as described in claim 1, characterized in that, In step S4, the static foaming, annealing and cooling are as follows: keep at 1150~1320℃ for 0.5~2h, then cool down to 850~1000℃ at -5~-15℃ / min, keep at 850~1000℃ for 10~60min, and then cool down to room temperature at -2~-8℃ / min.

6. The method for preparing ceramic-based porous thermal insulation material based on waste hot slag as described in claim 1, characterized in that, In step S4, the obtained ceramic-based porous insulation material has a pore size of 0.5~3.5mm, a porosity of 50%~85%, a thermal conductivity of 0.08~0.32W / (m·K), a compressive strength of 1~25 MPa, and a volume water absorption rate of 0.5%~5%.

7. A ceramic-based porous thermal insulation material based on waste hot slag, prepared by the preparation method according to any one of claims 1 to 6.

8. The application of a ceramic-based porous thermal insulation material based on waste hot slag as described in claim 7 in the construction of building walls.

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