A lightweight porous ceramic material based on multi-source solid waste and its preparation method

Abstract

This invention relates to the technical field of porous ceramic materials, and discloses a lightweight porous ceramic material based on multi-source solid waste and its preparation method. The lightweight porous ceramic material is obtained by firing mixed powder, which has a core-shell structure consisting of a core layer and an outer shell layer. The raw materials for the core layer include polishing waste, fluorine-rich waste, silicon-rich waste, foaming agent, and other raw materials; the raw materials for the outer shell layer include clay and fluorine-rich waste. This invention transforms three types of waste into valuable resources, recycles the waste, reduces environmental pollution from waste disposal, and lowers production costs. Moreover, by adjusting the optimal ratio of the three types of waste and forming a core-shell structure, foamed ceramic materials with high flexural strength, low bulk density, and relatively uniform foaming can be prepared at lower temperatures.

Description

Technical Field

[0001] This invention belongs to the technical field of porous ceramic materials, specifically relating to a lightweight porous ceramic material based on multi-source solid waste and its preparation method. Background Technology

[0002] The ceramics industry, being a high-energy-consuming and high-polluting sector, generates a large amount of solid waste during production. Among this, polishing waste (polishing slag) produced during the polishing of polished ceramic tiles is one of the main types of solid waste. Currently, the resource utilization of polishing waste is in its initial stage and faces significant technical challenges: its composition includes substances such as SiC and magnesium oxychloride cement (derived from polishing grinding heads), which can easily cause foaming and deformation of the finished products during high-temperature firing. This severely limits the resource utilization of polishing waste, and the accumulation of large amounts of polishing waste not only wastes resources but also exacerbates soil, water, and air pollution.

[0003] To achieve the resource utilization of polishing waste, existing technologies have attempted to use its high-temperature foaming properties to prepare porous ceramics. However, there are key technical problems: polishing waste contains particles with ultra-high refractoriness and chemical inertness, which means that the preparation of porous ceramics requires high-temperature firing conditions of ≥1200℃. This condition not only consumes a lot of energy and mineral resources, greatly increasing production costs, but also contradicts the industrial demand for energy conservation and environmental protection, thus limiting the large-scale application of this technology.

[0004] Lithium extraction waste residue, as another major type of solid waste, contains fluorine-rich waste (containing fluorides) which can lower the firing temperature of ceramics, and silicon-rich waste (containing a large amount of SiO2) which can enhance the strength of ceramic materials. Theoretically, this can solve the problems of high-temperature energy consumption and insufficient strength in the preparation of porous ceramics from polishing waste. However, at present, the industry has not formed a technical solution for the synergistic utilization of polishing waste and lithium extraction waste residue to prepare high-performance porous ceramics, and the synergistic resource utilization potential of multi-source solid waste has not been explored.

[0005] Furthermore, the existing methods for utilizing ceramic waste are relatively limited, mainly for preparing porcelain tiles. This results in low waste consumption and fails to fundamentally address the core issues of ceramic solid waste accumulation and environmental pollution. It also makes it difficult to achieve efficient utilization of solid waste resources. Meanwhile, during the preparation of porous ceramics, insufficient body strength, poor thermal stability, and unstable sintering behavior lead to low mechanical strength of foamed ceramics, further restricting the industrial application of solid waste-based porous ceramics.

[0006] In summary, there are currently many technical bottlenecks in the resource utilization of ceramic solid waste: the resource utilization of polishing waste is difficult, the firing temperature of porous ceramics is high and the energy consumption is large, the technology for the synergistic utilization of multi-source solid waste is lacking, the mechanical properties of green bodies and finished products are insufficient, and the existing utilization methods are inefficient. These technical problems urgently need to be solved by an efficient and energy-saving technical solution. Summary of the Invention

[0007] The main objective of this invention is to address the aforementioned problems by providing a lightweight porous ceramic material based on multi-source solid waste and its preparation method. Through the combined action of polishing waste, fluorine-rich waste, and silicon-rich waste, and the formation of a core-shell structure, a foamed ceramic material with high flexural strength, low bulk density, and uniform foaming can be prepared at a relatively low temperature. This transforms the three types of waste into valuable resources, reducing environmental pollution from waste disposal while lowering production costs.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: One of the technical solutions of the present invention is as follows: the lightweight porous ceramic material is obtained by firing mixed powder, the mixed powder is a core-shell structure consisting of a core layer and an outer shell layer, the thickness of the outer shell layer is 100~300μm; the raw materials of the core layer include waste materials and foaming agent accounting for 0.01~1% of the waste materials, the waste materials include, by mass percentage: 40~80% polishing waste, 1~20% fluorine-rich waste, 1~20% silicon-rich waste and other raw materials; the raw materials of the outer shell layer include, by mass percentage: 70~90% clay and 10~30% fluorine-rich waste.

[0009] Polishing waste primarily consists of SiO2 and Al2O3, with small amounts of fluxing agents such as K2O, Na2O, CaO, and MgO. Introducing an appropriate amount of polishing waste can broaden the sintering temperature range; however, excessive amounts will narrow this range, hindering production and causing over-foaming of the green body, structural damage, and significantly reduced strength. Therefore, while ensuring an appropriate amount of polishing waste, adding a small amount of foaming agent can better promote foaming. However, excessive foaming agent content leads to larger pores in the green body, incomplete reaction of some foaming agents, and blackening of the sample's interior, failing to meet usage requirements. Insufficient foaming agent content results in difficult foaming. The addition of fluorine-rich waste can significantly reduce the material's melting temperature and high-temperature melt viscosity, facilitating the formation of uniform, round pores. However, excessive addition greatly reduces melt viscosity and surface tension, leading to excessively large internal bubbles and reduced flexural strength. Insufficient addition fails to effectively reduce melt viscosity and promote crystallization, resulting in difficult foaming. Silicon-rich waste contains a large amount of SiO2, which can replace quartz as the skeleton of the green body. An appropriate amount of silicon-rich waste can significantly improve the flexural strength of the product. However, excessive amounts will increase the melting temperature and viscosity, inhibit melting and gas expansion, leading to difficult and insufficient foaming, decreased porosity, smaller pore size, and a tendency for the product to become denser. Insufficient amounts may fail to form a stable skeleton, resulting in reduced strength. Therefore, this invention, through extensive exploratory experiments, has determined the optimal ratio of the three types of waste, enabling the preparation of foamed ceramic materials with high flexural strength, low bulk density, and relatively uniform foaming at lower temperatures.

[0010] Furthermore, this invention uses foamed ceramic material obtained from multi-source solid waste as the core layer and clay and fluorine-rich waste as the outer shell layer for encapsulation. This not only improves the mechanical properties of the ceramic material but also avoids structural instability caused by over-foaming of the core layer. The encapsulated outer shell layer enhances the structural stability of the porous ceramic while maintaining a low bulk density. Utilizing the strong fluxing property of fluorine-rich waste, it preferentially melts during firing to form a high-viscosity liquid phase, causing preferential densification of the outer shell. Simultaneously, the clay forms mullite crystals at high temperatures, improving the mechanical properties of the product. The core decomposes to generate gas, and the internal pressure gradually increases. When the gas pressure is high enough, the softened outer shell layer is slowly expanded, increasing the volume of the green body. When the pressure exceeds the outer shell layer's tolerance limit, some gas is released through tiny channels or weak points in the outer shell layer. After the pressure drops, due to surface tension, the liquid phase in the outer shell layer reflows and closes, retaining the remaining closed pores. When the coating layer is too thin, it cannot effectively confine the release of internal gases during firing, causing gases to escape prematurely and rapidly, resulting in a coarse and unevenly distributed porous structure within the material. Simultaneously, the lack of sufficient high-temperature liquid phase to promote particle bonding and densification leads to a loose structure and reduced flexural strength. Conversely, when the coating layer is too thick or too long, it reduces particle sphericity. An excessively thick shell severely hinders gas release and expansion during firing. It also generates too much liquid phase, easily causing softening, deformation, or even collapse of the preform. This results in insufficient foaming and excessively high density in the final product.

[0011] More preferably, by mass percentage, the chemical composition of the waste raw materials in the core layer includes SiO2 60~70%, Al2O3 10~25%, Fe2O3 0~2%, CaO 1~4%, MgO 1~2%, K2O 2~4%, Na2O 1~3%, TiO2 0.1~0.3%, P2O5 0.2~0.5%, Li2O 0.1~0.3%, F 0~2%, and Cl 0~0.5%.

[0012] More preferably, the chemical composition of the outer shell layer, by mass percentage, includes 40-55% SiO2, 40-50% Al2O3, 0.2-0.5% Fe2O3, 2-8% CaO, 0.2-1% MgO, 0-0.5% K2O, 0-0.1% Na2O, 0-0.1% TiO2, 0-1% P2O5, 0-0.1% Li2O, 1-5% F, and 0-0.2% Cl.

[0013] More preferably, the foaming agent is SiC with a particle size of 1~10μm.

[0014] More preferably, the other raw materials include 0-20% clay and 0-10% potassium feldspar.

[0015] Further preferably, the raw materials for the core layer include waste materials and a foaming agent comprising 0.1-0.5% of the waste materials. The waste materials, by mass percentage, include: 65-70% polishing waste, 1-5% fluorine-rich waste, 1-10% silicon-rich waste, 10-20% clay, and 5-10% potassium feldspar. The raw materials for the outer shell layer, by mass percentage, include 80-90% clay and 10-20% fluorine-rich waste.

[0016] The second technical solution of the present invention: a method for preparing lightweight porous ceramic materials based on multi-source solid waste, comprising the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The raw materials of the core layer and the raw materials of the outer shell layer are wet ball milled and filtered to obtain core slurry and outer shell slurry; (3) Granulation: The core slurry and the outer shell slurry are spray-dried to obtain core layer powder and outer shell powder, respectively; (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll to obtain a fully coated mixed powder; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper, fire it, and obtain a lightweight porous ceramic material after cooling.

[0017] The raw materials are wrapped by a mixture of clay and fluorine-rich waste through a roller device, which significantly enhances the strength and thermal stability of the green body, stabilizes the sintering behavior, and improves the mechanical strength of foamed ceramics.

[0018] More preferably, in step (2), during wet ball milling, the mass ratio of raw material: ball: water is 1:2:0.6~1.2; and the wet ball milling time is 8~12h.

[0019] In a further preferred embodiment, during wet ball milling in step (2), a water-reducing agent is added to the core layer raw material and the outer shell layer raw material respectively, and the mass ratio of raw material and water-reducing agent: ball: water is 1:2:0.6~1.2; the wet ball milling time is 8~12h; and the amount of water-reducing agent added is 0.2-0.5% of the mass of the core layer raw material or the outer shell layer raw material.

[0020] Further preferably, the moisture content of the powder after spray drying in step (3) is 5-7%; the particle size of the core layer powder is 10-15 μm; and the particle size of the outer shell powder is 5-8 μm. The particle size of the outer shell layer also has a significant impact on the coating. When the particle size of the outer shell layer is fine, the finer particles will agglomerate during the coating process. These agglomerates adhere to the core, forming "small hills" on the surface, thus failing to form a uniform coating layer. This will lead to uneven foaming of the product during the firing process. At the same time, preparing finer particles will greatly increase power consumption and equipment wear, increasing production costs. When the particle size of the outer shell layer is coarse, the particle spacing will be large during the coating process, making it impossible to form a seal. This will lead to the formation of more interconnected irregular pores during the firing process, resulting in a significant reduction in the mechanical properties of the product.

[0021] More preferably, in step (4), the rotation speed of the roller device is 30-60 rpm, the rolling time is 20-40 min, and the thickness of the outer shell layer is 100-300 μm.

[0022] When the rolling time is too short, the resulting coating layer is discontinuous, too thin, and has poor uniformity. During firing, it cannot effectively confine the release of internal gases, thus reducing the product's flexural strength. When the rolling time is too long, the collisions between particles may be intense, causing the coating layer to peel off. It may also result in an excessively thick and dense coating layer, leading to insufficient foaming and excessively high density in the product.

[0023] More preferably, the firing temperature in step (5) is 1080~1150℃, the heating rate is 2~10℃ / min, and the holding time is 20~120min.

[0024] Compared with existing technologies, this invention has the following advantages: it turns three types of waste into valuable resources, recycles the waste, reduces environmental pollution caused by waste disposal, and lowers production costs; moreover, by adjusting the optimal ratio of the three types of waste and forming a core-shell structure, it is possible to prepare foamed ceramic materials with high flexural strength, low bulk density, and relatively uniform foaming at lower temperatures. Attached Figure Description

[0025] Figure 1 These are appearance images of the porous ceramic materials prepared in Examples 1-5; Figure 2 The images show the appearance of the porous ceramic materials prepared in Comparative Examples 1-5. Detailed Implementation

[0026] The following embodiments further illustrate the above-described content of the present invention in detail, but it should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. The raw materials for the body and the glaze all adopt commonly used specifications and dimensions in the art.

[0027] Example 1 The raw material composition of the core layer is as follows: 50wt% polishing waste, 12.5wt% fluorine-rich waste, 12.5wt% silicon-rich waste, 12.5wt% clay, 12.5wt% potassium feldspar, and 0.2% foaming agent SiC.

[0028] The raw material composition of the outer shell layer is: 70wt% clay and 30wt% fluorine-rich waste.

[0029] The preparation of lightweight porous ceramic materials includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried to obtain core layer powder with a moisture content of 5~7% and a particle size of 14±1μm and outer shell powder with a moisture content of 5~7% and a particle size of 7±1μm. (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll for 30 minutes at a speed of 40 rpm to obtain a mixed powder with full coating and an outer shell thickness of 200±20 μm; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper and place it in a kiln for firing. The firing temperature is 1150℃, the heating rate is 2℃ / min, and the maximum temperature is held for 30min. After cooling, a lightweight porous ceramic material is obtained.

[0030] Example 2 The raw material composition of the core layer is as follows: 65wt% polishing waste, 5wt% fluorine-rich waste, 10wt% silicon-rich waste, 10wt% clay, 10wt% potassium feldspar, and 0.1% foaming agent SiC.

[0031] The raw material composition of the outer shell layer is: 80wt% clay and 20wt% fluorine-rich waste.

[0032] The preparation of lightweight porous ceramic materials includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried to obtain core layer powder with a moisture content of 5~7% and a particle size of 14±1μm and outer shell powder with a moisture content of 5~7% and a particle size of 7±1μm. (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll for 30 minutes at a speed of 40 rpm to obtain a mixed powder with full coating and an outer shell thickness of 200±20 μm; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper and place it in a kiln for firing. The firing temperature is 1130℃, the heating rate is 2℃ / min, and the maximum temperature is held for 30min. After cooling, a lightweight porous ceramic material is obtained.

[0033] Example 3 The raw material composition of the core layer is as follows: 70wt% polishing waste, 5wt% fluorine-rich waste, 10wt% silicon-rich waste, 10wt% clay, 5wt% potassium feldspar, and 0.1% foaming agent SiC.

[0034] The raw material composition of the outer shell layer is: 90wt% clay and 10wt% fluorine-rich waste.

[0035] The preparation of lightweight porous ceramic materials includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried to obtain core layer powder with a moisture content of 5~7% and a particle size of 14±1μm and outer shell powder with a moisture content of 5~7% and a particle size of 7±1μm. (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll for 30 minutes at a speed of 40 rpm to obtain a mixed powder with full coating and an outer shell thickness of 200±20 μm; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper and place it in a kiln for firing. The firing temperature is 1130℃, the heating rate is 2℃ / min, and the maximum temperature is held for 30min. After cooling, a lightweight porous ceramic material is obtained.

[0036] Example 4 The raw material composition of the core layer is as follows: 70wt% polishing waste, 5wt% fluorine-rich waste, 10wt% silicon-rich waste, 10wt% clay, 5wt% potassium feldspar, and 0.1% foaming agent SiC.

[0037] The raw material composition of the outer shell layer is: 80wt% clay and 20wt% fluorine-rich waste.

[0038] The preparation of lightweight porous ceramic materials includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried to obtain core layer powder with a moisture content of 5~7% and a particle size of 14±1μm and outer shell powder with a moisture content of 5~7% and a particle size of 7±1μm. (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll for 30 minutes at a speed of 40 rpm to obtain a mixed powder with full coating and an outer shell thickness of 200±20 μm; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper and place it in a kiln for firing. The firing temperature is 1100℃, the heating rate is 2℃ / min, and the maximum temperature is held for 30min. After cooling, a lightweight porous ceramic material is obtained.

[0039] Example 5 The raw material composition of the core layer is as follows: 75wt% polishing waste, 5wt% fluorine-rich waste, 10wt% silicon-rich waste, 10wt% clay, and 0.1% foaming agent SiC.

[0040] The raw material composition of the outer shell layer is: 80wt% clay and 20wt% fluorine-rich waste.

[0041] The preparation of lightweight porous ceramic materials includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried to obtain core layer powder with a moisture content of 5~7% and a particle size of 14±1μm and outer shell powder with a moisture content of 5~7% and a particle size of 7±1μm. (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll for 30 minutes at a speed of 40 rpm to obtain a mixed powder with full coating and an outer shell thickness of 200±20 μm; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper and place it in a kiln for firing. The firing temperature is 1150℃, the heating rate is 5℃ / min, and the maximum temperature is held for 60min. After cooling, a lightweight porous ceramic material is obtained.

[0042] Comparative Example 1 The only difference between this comparative example and Example 2 is that too much polishing waste and too little fluorine-rich waste were added to the core layer.

[0043] The raw material composition of the core layer is: 35wt% polishing waste, 25wt% fluorine-rich waste, 20wt% silicon-rich waste, 10wt% clay, 10wt% potassium feldspar, and 0.1% SiC foaming agent. The raw material composition of the outer shell layer is: 80wt% clay and 20wt% fluorine-rich waste. The preparation method of the porous ceramic material is the same as in Example 2.

[0044] Comparative Example 2 The only difference between this comparative example and Example 5 is that too much polishing waste was added to the core layer and no foaming agent was added.

[0045] The raw material composition of the core layer is: 85wt% polishing waste, 5wt% fluorine-rich waste, 5wt% silicon-rich waste, and 5wt% clay. The raw material composition of the outer shell layer is: 80wt% clay and 20wt% fluorine-rich waste. The preparation method of the porous ceramic material is the same as in Example 2.

[0046] Comparative Example 3 The only difference between this comparative example and Example 2 is that silicon-rich waste is added to the outer shell layer instead of fluorine-rich waste.

[0047] The core layer consists of the following raw materials: 65wt% polishing waste, 5wt% fluorine-rich waste, 10wt% silicon-rich waste, 10wt% clay, 10wt% potassium feldspar, and 0.1% SiC foaming agent. The outer shell layer consists of the following raw materials: 80wt% clay and 20wt% silicon-rich waste.

[0048] The preparation of porous ceramic materials includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried to obtain core layer powder with a moisture content of 5~7% and a particle size of 14±1μm and outer shell powder with a moisture content of 5~7% and a particle size of 7±1μm. (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll for 30 minutes at a speed of 40 rpm to obtain a mixed powder with full coating and an outer shell thickness of 200±20 μm; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper and place it in a kiln for firing. The firing temperature is 1200℃, the heating rate is 2℃ / min, and the maximum temperature is held for 30min. After cooling, a lightweight porous ceramic material is obtained.

[0049] Comparative Example 4 This comparative example uses the same porous ceramic material as Example 2. The only difference from Example 2 is that in step (4), the rolling speed is too high and the rolling time is too long.

[0050] Specifically, the steps include the following: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried to obtain core layer powder with a moisture content of 5~7% and a particle size of 14±1μm and outer shell powder with a moisture content of 5~7% and a particle size of 7±1μm. (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll for 50 minutes at a speed of 70 rpm to obtain a mixed powder with full coating and an outer shell thickness of 350±20μm; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper and place it in a kiln for firing. The firing temperature is 1130℃, the heating rate is 2℃ / min, and the maximum temperature is held for 30min. After cooling, a lightweight porous ceramic material is obtained.

[0051] Comparative Example 5 The only difference between this comparative example and Example 2 is that the porous ceramic material is not encased in a shell layer.

[0052] The raw material composition of the porous ceramic material is as follows: 65wt% polishing waste, 5wt% fluorine-rich waste, 10wt% silicon-rich waste, 10wt% clay, 10wt% potassium feldspar, and 0.1% foaming agent SiC.

[0053] The preparation of porous ceramic materials includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The core layer raw material and the outer shell layer raw material are placed into the ball mill jar respectively, and 0.3% of the raw material amount of water-reducing agent (sodium tripolyphosphate) is added. The ball mill and water are added according to the mass ratio of raw material + water-reducing agent: ball: water = 1:2:1. The ball mill is milled for 9 hours. After filtration, the ball mill is filtered out to obtain the core slurry and the outer shell slurry. (3) Granulation: The core mud and the outer shell mud are spray dried separately to obtain powder with a moisture content of 5~7% and a particle size of 14±1μm; (4) Firing: Spread the powder evenly on the aluminum silicate fiber paper and place it in the kiln for firing. The firing temperature is 1130℃, the heating rate is 2℃ / min, and the maximum temperature is held for 30min. After cooling, porous ceramic material is obtained.

[0054] Table 1. Chemical composition (%) of Examples 1-5 Table 2 Chemical composition (%) of Comparative Examples 1-5 Tables 1 and 2 show the chemical composition of the core layer (waste raw material in the core layer) and outer shell layer in Examples 1-5 and Comparative Examples 1-5, and the performance of the prepared porous ceramic material products was tested. Flexural strength and water absorption were tested according to GB / T5486-2008, and apparent porosity and bulk density were tested according to GB / T 1966-2024. Higher water absorption corresponds to lower bulk density; higher apparent porosity corresponds to lower flexural strength.

[0055] Table 3 Performance test data of ceramic materials in Examples 1-5 and Comparative Examples 1-5 As shown in Table 3, compared with Comparative Examples 1-5, Examples 1-5 possess superior properties such as lightweight and high strength. Furthermore, combined with... Figure 1 As shown, among Examples 1-5, Examples 2-4 have better performance, with higher flexural strength and smaller and more uniform foaming while having a lower bulk density.

[0056] like Figure 2 The figures shown are the appearance images of porous ceramic materials in Comparative Examples 1-5. Analysis of Table 3 reveals that in Comparative Example 1, due to the low content of polishing waste, the total amount of foaming components in the green body was insufficient, resulting in poor foaming during firing. The product's bulk density and flexural strength were both at a high level. Compared to Example 2, the pore size of the product in Comparative Example 1 was smaller. Comparative Example 2 increased the content of polishing waste without adding additional foaming agent. However, because the polishing waste contained relatively little foaming component, it also reduced the foaming of the product, increasing the bulk density and decreasing the pore size. Comparative Example 3 used silicon-rich waste instead of fluorine-rich waste, increasing the amount of liquid phase in the outer shell layer. This change made the green body more densely sintered, leading to an increase in the product's bulk density and flexural strength, but the increase in flexural strength was relatively small, and the foaming uniformity was also reduced. Simultaneously, the SiO2 contained in the silicon-rich waste increased the liquid phase generation temperature during firing, requiring the product to be fired at a higher temperature, significantly increasing production costs. Comparative Example 4 increased the thickness of the outer shell layer by extending the rolling time and increasing the rotation speed. While thickening the outer shell can improve flexural strength, an excessively thick outer shell increases the overall density, affecting foaming and resulting in a product bulk density greater than 1 g / cm³. 3 This method fails to meet the requirement of lightweight construction. In Comparative Example 5, due to the lack of a coating layer structure, adjacent pores within the green body tend to merge during firing, forming large pores. This change in pore structure disrupts the uniformity of the green body, leading to a decrease in the product's bulk density and flexural strength.

[0057] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0058] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A lightweight porous ceramic material based on multi-source solid waste, characterized in that, The lightweight porous ceramic material is obtained by firing a mixed powder. The mixed powder has a core-shell structure consisting of a core layer and an outer shell layer. The thickness of the outer shell layer is 100~300μm. The raw materials of the core layer include waste materials and a foaming agent accounting for 0.01~1% of the waste materials. The waste materials include, by mass percentage: 40~80% polishing waste, 1~20% fluorine-rich waste, 1~20% silicon-rich waste, and other raw materials. The raw materials of the outer shell layer include, by mass percentage: 70~90% clay and 10~30% fluorine-rich waste.

2. The lightweight porous ceramic material based on multi-source solid waste as described in claim 1, characterized in that, The chemical composition of the waste materials in the core layer, by mass percentage, includes: SiO2 60-70%, Al2O3 10-25%, Fe2O3 0-2%, CaO 1-4%, MgO 1-2%, K2O 2-4%, Na2O 1-3%, TiO2 0.1-0.3%, P2O5 0.2-0.5%, Li2O 0.1-0.3%, F 0-2%, and Cl 0-0.5%.

3. The lightweight porous ceramic material based on multi-source solid waste as described in claim 1 or 2, characterized in that, The chemical composition of the outer shell layer, by mass percentage, includes: SiO2 40-55%, Al2O3 40-50%, Fe2O3 0.2-0.5%, CaO 2-8%, MgO 0.2-1%, K2O 0-0.5%, Na2O 0-0.1%, TiO2 0-0.1%, P2O5 0-1%, Li2O 0-0.1%, F 1-5%, and Cl 0-0.2%.

4. The lightweight porous ceramic material based on multi-source solid waste as described in claim 1, characterized in that, The foaming agent is SiC with a particle size of 1~10μm.

5. The lightweight porous ceramic material based on multi-source solid waste as described in claim 1 or 4, characterized in that, The other raw materials include 0-20% clay and 0-10% potassium feldspar.

6. A method for preparing a lightweight porous ceramic material based on multi-source solid waste as described in any one of claims 1-5, characterized in that, Includes the following steps: (1) Ingredients: Ingredients are mixed according to a certain ratio to obtain the core layer raw materials and the outer shell layer raw materials respectively; (2) Pulping: The raw materials of the core layer and the raw materials of the outer shell layer are wet ball milled and filtered to obtain core slurry and outer shell slurry; (3) Granulation: The core slurry and the outer shell slurry are spray-dried to obtain core layer powder and outer shell powder, respectively; (4) Coating: Add the core layer powder into the roller device, spray water mist, add the outer shell powder and roll to obtain a fully coated mixed powder; (5) Firing: Spread the mixed powder evenly on aluminum silicate fiber paper, fire it, and obtain a lightweight porous ceramic material after cooling.

7. The method for preparing lightweight porous ceramic materials based on multi-source solid waste as described in claim 6, characterized in that, In step (2), the mass ratio of raw material: ball: water during wet ball milling is 1:2:0.6~1.2; the wet ball milling time is 8~12h.

8. The method for preparing lightweight porous ceramic materials based on multi-source solid waste as described in claim 6 or 7, characterized in that, In step (3), the moisture content of the powder after spray drying is 5-7%; the particle size of the core layer powder is 10-15 μm; and the particle size of the outer shell powder is 5-8 μm.

9. The method for preparing lightweight porous ceramic materials based on multi-source solid waste as described in claim 6, characterized in that, In step (4), the rotation speed of the roller device is 30-60 rpm and the rolling time is 20-40 min.

10. The method for preparing lightweight porous ceramic materials based on multi-source solid waste as described in claim 6 or 9, characterized in that, In step (5), the firing temperature is 1080~1150℃, the heating rate is 2~10℃ / min, and the holding time is 20~120min.

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