Gradient hole structure garbage incineration furnace slag foamed ceramic and two-stage firing method thereof

Abstract

This invention discloses a gradient-pore structure for foamed ceramics based on municipal solid waste incineration slag and its two-stage firing method, belonging to the technical field of solid waste utilization and building materials. The material comprises 50-70 parts of municipal solid waste incineration slag, 0-15 parts of kaolin, 20-40 parts of tailings slag, 3-15 parts of feldspar, 0-5 parts of talc, 0.2-0.35 parts of a gradient foaming agent, and 1-3 parts of additives, and is mainly prepared through a two-stage high-temperature firing process. This invention reduces the sintering temperature and energy cost of the foamed ceramics, achieving the harmlessness and resource utilization of the slag. The two-stage firing process, combined with a gradient foaming agent, forms a gradient-pore structure with pore sizes ranging from small to large and pore walls gradually becoming denser with increasing temperature. This solves the problems of low closed-cell rate and uneven pore size distribution caused by the difficulty in controlling the valence state transformation of iron in the slag and the inability of a single foaming agent to meet the foaming requirements of the slag in different temperature ranges, thus realizing the preparation of high-performance slag-based foamed ceramics.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization and building ceramic materials technology, and in particular to gradient pore structure waste incinerator slag foamed ceramics and their two-stage firing method. Background Technology

[0002] Municipal solid waste incineration has become an effective way to solve the problem of urban waste accumulation. Data shows that after incineration, the volume of municipal solid waste can be reduced by more than 90%, and its weight by more than 80%. The solid residue produced by incineration mainly includes fly ash and slag. Fly ash is hazardous waste, rich in heavy metals and dioxins, and its disposal requires strict control. In contrast, municipal solid waste incineration slag is a large-particle solid residue discharged from the incineration bed after combustion. Its heavy metal content is lower than that of fly ash, but its large output and the land occupation required for its storage pose the same environmental risks.

[0003] Currently, the main methods for treating municipal solid waste incineration slag include landfilling and use as road base materials or concrete aggregates. However, the high chloride content in the slag severely limits its use in cement concrete materials, and these methods cannot achieve high-value utilization of the slag. It is worth noting that slag contains a significant amount of SiO2 and Al2O3, theoretically making it an excellent raw material for preparing foamed ceramics; however, there is currently no mature technology for preparing foamed ceramics using slag as the main raw material.

[0004] Foamed ceramics are lightweight, high-performance ceramic materials with numerous closed pores. They possess advantages such as light weight, high strength, heat insulation, fire resistance, and weather resistance, and are widely used in building insulation, decoration, and partition systems. Using industrial solid waste (such as fly ash, coal gangue, tailings, and ceramic waste) as the main raw material to prepare foamed ceramics is an important way to achieve high-value utilization of solid waste.

[0005] However, there are very few patents and studies on the preparation of foamed ceramics from municipal solid waste incineration slag. Existing technologies mainly focus on the utilization of fly ash. For example, Chinese patent application number CN202110684340.0 discloses a formula and method for producing foamed ceramics with waste incineration fly ash as the main component. However, fly ash and slag have significant differences in composition and characteristics. Fly ash contains more heavy metals and calcium compounds, while slag is mainly composed of compounds such as silicon, aluminum and calcium. Therefore, the disposal method of fly ash cannot be directly used for slag. Chinese patent application number CN201921442425.2 discloses an energy-saving and efficient tunnel kiln for firing multi-layer foamed ceramics, but it does not solve the problem of preparing foamed ceramics using slag as raw material; Chinese patent application number CN202310470119.4 discloses a foamed ceramic synthesized using fly ash and lithium slag, but fly ash has different composition and characteristics from municipal solid waste incinerator slag and cannot be directly used as a reference.

[0006] More notably, the slag from municipal solid waste incineration contains a large amount of iron (mainly Fe). 2+ and Fe 3+ In traditional firing processes, the valence state transformation of iron is difficult to control, leading to unstable foaming processes, uneven pore structures, and large fluctuations in product performance. Existing technologies do not yet have a gradient foaming agent system designed specifically for the characteristics of iron in slag, nor a two-stage firing process, making it difficult to achieve high performance and industrial application of slag-based foamed ceramics. Summary of the Invention

[0007] This invention provides gradient pore structure waste incinerator slag foamed ceramics and their two-stage firing method. Its main purpose is to achieve the preparation of high-performance slag-based foamed ceramics by precisely controlling the foaming behavior and iron valence state transformation in different temperature ranges.

[0008] To achieve the above objectives, the present invention provides a gradient-pore structure waste incinerator slag foamed ceramic and a two-stage firing method thereof. The raw materials (by mass parts) of the gradient-pore structure waste incinerator slag foamed ceramic include 50-70 parts of municipal solid waste incinerator slag, 0-15 parts of kaolin, 20-40 parts of tailings slag, 3-15 parts of feldspar, 0-5 parts of talc, 0.2-0.35 parts of gradient foaming agent, and 1-3 parts of additives.

[0009] Furthermore, the gradient foaming agent is composed of a low-temperature foaming agent, a medium-temperature foaming agent, and a high-temperature foaming agent. The low-temperature foaming agent generates CO2 gas in the temperature decomposition range of 600-800℃, the medium-temperature foaming agent generates CO2 gas in the temperature decomposition range of 800-1000℃, and the high-temperature foaming agent generates CO gas in the temperature decomposition range of 1100-1250℃. The three gases work synergistically in different temperature ranges to form a uniform gradient pore structure. The ratio of the low-temperature foaming agent, the medium-temperature foaming agent, and the high-temperature foaming agent is 1-1.5:0.5-1:0.5-1.

[0010] Furthermore, the low-temperature foaming agent is CaCO3, the medium-temperature foaming agent is Fe2O3, and the high-temperature foaming agent is SiC.

[0011] The additive is an alkaline substance that can adjust pH value and solidify heavy metals, and is selected from at least one of calcium hydroxide, sodium hydroxide, and sodium carbonate.

[0012] A two-stage firing method for preparing gradient-pore structured waste incinerator slag foamed ceramics includes the following steps: S1. Pre-treat the slag from municipal solid waste incineration furnaces to obtain slag filter cake; S2. The slag filter cake is coarsely crushed, batched and initially mixed with other required raw materials to obtain a mixture. The other required raw materials include kaolin, tailings slag, feldspar, talc, gradient foaming agent and additives, and are made according to the raw material ratio of the gradient pore structure waste incineration slag foamed ceramic. S3. The mixture is ground and crushed using a wet process to form fine crushed material; S4. The finely crushed material is subjected to wet spray powdering to obtain a mixed powder. S5. The mixed powder is molded, distributed, dried, and preheated. S6. The preheated material is placed into a tunnel kiln for two-stage high-temperature firing to obtain a semi-finished foamed ceramic board. S61. Perform the first stage of firing, set the temperature to 800-950℃, pre-foam in a reducing atmosphere, hold for 0.5-1.5h, and raise the temperature at a rate of 100-200℃ / h. S62. Perform the second stage of firing at a temperature of 1100-1250℃. Densification and pore structure stabilization are carried out in an oxidizing atmosphere. Hold the temperature for 1-2 hours and the heating rate is 200-300℃ / h. S63. First, cool down to 600℃ at a rate of 400-600℃ / h, then cool down from 600℃ to room temperature at a rate of 200-400℃ / h. S7. Inspect, select, and trim the foamed ceramic board semi-finished product to obtain the finished product and put it into storage.

[0013] Furthermore, the pretreatment in step S1 includes washing and pressing the municipal solid waste incinerator slag with water, wherein the ratio of municipal solid waste incinerator slag to water is 1:0.9-1, the moisture content of the slag filter cake is controlled to be less than 12%, and the total chloride ion content is controlled to be less than 2%.

[0014] Furthermore, the maximum particle size of the mixture is 2 mm, and the particle size of the mixed powder is no greater than 200 mesh.

[0015] Furthermore, in step S5, the preheating temperature is 100-600℃ and the preheating time is 2-4 hours.

[0016] Furthermore, in step S5, the pressure for pressing the powder in the mold is adjusted according to the density of the product to be produced. The pressure adjustment range is 0-12MPa, and the density of the product to be produced is controlled between 0.3 and 1.0t / m³.

[0017] Furthermore, the reducing atmosphere in step S6 is a mixed gas with a CO concentration of 5%–15%, and the oxidizing atmosphere is air or oxygen-enriched air.

[0018] The beneficial effects of the gradient pore structure waste incinerator slag foamed ceramic and its two-stage firing method provided by this invention are as follows: By optimizing the existing process formula, using municipal solid waste incineration slag as the main raw material for producing foamed ceramics, the sintering temperature and energy cost of foamed ceramics are reduced, and the heavy metals in the slag are solidified by the synergistic effect between the components, thus achieving the harmlessness and resource utilization of the slag. By accurately calculating water consumption and adopting a related material recycling system, the entire production process can save resources and energy to the greatest extent, and the density of the produced ceramic products can be controlled to meet different needs. By employing a two-stage firing process combined with a gradient foaming agent, the foaming behavior and iron valence state transformation in different temperature ranges are precisely controlled to form a gradient pore structure. This solves the problems of low closed-cell rate and uneven pore size distribution caused by the difficulty in controlling the iron valence state transformation in slag and the inability of a single foaming agent to meet the foaming requirements of slag in different temperature ranges. This enables the preparation of high-performance slag-based foamed ceramics. Attached Figure Description

[0019] Figure 1 A schematic diagram of the process for the gradient pore structure waste incinerator slag foamed ceramic and its two-stage firing method provided by the present invention. Detailed Implementation

[0020] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without creative effort are within the scope of protection of the invention.

[0021] This invention provides a gradient pore structure for foamed ceramics made from waste incinerator slag and a two-stage firing method thereof. Some embodiments of this invention will be described in detail below with reference to the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other. Example

[0022] The gradient pore structure of the waste incinerator slag foamed ceramic, wherein the raw materials of the foamed ceramic (by mass parts) include 55 parts of municipal solid waste incinerator slag, 8 parts of low-quality kaolin, 32 parts of quartz tailings, 8 parts of feldspar, 2 parts of talc, 0.25 parts of gradient foaming agent, and 2 parts of additives.

[0023] This embodiment uses municipal solid waste incineration slag as the main raw material, which contains basic components such as SiO2 and Al2O3. Kaolin mainly provides Al2O3 to regulate the sintering temperature. Quartz tailings are used to supplement the overall SiO2 content. Feldspar is used as a flux, and talc is used to adjust the coefficient of thermal expansion and improve thermal shock resistance.

[0024] In this embodiment, 0.25 parts of gradient foaming agent consists of 0.12 parts of CaCO3, 0.06 parts of Fe2O3, and 0.07 parts of SiC. CaCO3 is a low-temperature foaming agent that decomposes in the temperature range of 600-800℃ to generate CO2 gas, forming primary pore nuclei and laying the foundation for subsequent foaming. Fe2O3 is a medium-temperature foaming agent that reacts with CO in a reducing atmosphere of 800-1000℃ to generate Fe3O4 and release CO2 gas, promoting pore nuclei growth and regulating the valence state distribution of iron in the system to achieve fine control of the pore structure, laying the foundation for high-temperature oxidation densification. SiC is a high-temperature foaming agent that reacts with SiO2 in the temperature range of 1100-1250℃ to generate CO gas, producing a secondary foaming effect, densifying the pore walls, forming a gradient pore structure, and improving product strength.

[0025] The additive is an alkaline substance used to adjust the pH value and can further solidify heavy metals. In this example, the two parts of the additive consist of 1.5 parts calcium hydroxide and 0.5 parts sodium carbonate.

[0026] In this embodiment, combined with Figure 1 The two-stage firing method for the gradient pore structure waste incinerator slag foamed ceramic includes the following steps: S1. Pretreatment of municipal solid waste incineration slag; First, the slag and water from the municipal solid waste incineration furnace are washed in a 1:1 ratio to fully leach out the chloride ions from the slag. The slag is then dehydrated by pressure filtration to obtain a slag filter cake, and the filtrate is evaporated and crystallized.

[0027] During the pretreatment process, the moisture content of the slag after water washing is controlled at 10%, and the total chloride ion content is controlled at 0.9%.

[0028] S2. The required raw materials are coarsely crushed, batched, and initially mixed. The above raw materials are coarsely crushed to ensure that the particle size is no larger than 2mm. The various raw materials are accurately measured and mixed according to the formula ratio to obtain the mixture.

[0029] S3. The mixture is ground and crushed using a wet process to form fine crushed material; S4. Perform wet spray grinding on the fine crushed material to make the particle size of the mixed powder ≤200 mesh; In this step, the particle size distribution of the mixed powder is as follows: 40-60 mesh accounts for 15%, 60-80 mesh accounts for 55%, 80-100 mesh accounts for 22%, and larger than 100 mesh accounts for 8%.

[0030] S5. Distribute and preheat the mixed powder; Specifically, the mixed powder is loaded into a mold and preheated in a drying kiln at a temperature of 450°C for 3 hours.

[0031] S6. The preheated material is placed into a tunnel kiln for two-stage high-temperature firing to form the shape. First, the first stage of firing is carried out, with the temperature set at 850℃. Pre-foaming is performed in a reducing atmosphere (CO concentration 8%), and the temperature is held for 1.0 h with a heating rate of 150℃ / h. Then, the second firing stage is carried out at a temperature of 1150℃, and densification and pore structure stabilization are carried out in an oxidizing atmosphere (air), with a holding time of 1.5h and a heating rate of 250℃ / h. Finally, the temperature was first lowered from 1150℃ to 600℃ at a rate of 500℃ / h; then it was lowered from 600℃ to room temperature at a rate of 300℃ / h.

[0032] In this step, the first firing stage mainly completes the decomposition of the low-temperature foaming agent and the preliminary reaction of the medium-temperature foaming agent, while simultaneously removing Fe from the slag. 3+ Partially reduced to Fe 2+ This creates conditions for subsequent foaming; the second firing stage mainly completes the full reaction of the high-temperature foaming agent, while also removing Fe. 2+ Oxidized to Fe 3+ This allows the glass phase on the pore walls to fully melt and densify, thereby improving the product strength.

[0033] S7. Inspect, select, and trim the semi-finished foamed ceramic panels to obtain the final finished product and put it into storage.

[0034] The foamed ceramic product prepared according to the raw materials and method in this embodiment has a uniform cross-sectional pore structure, and the relevant test data are as follows: The closed-cell rate reaches 96.2%, the compressive strength is 13.5MPa, the thermal conductivity is 0.22W / (m·K), the leaching amount of heavy metal Pb is <0.008mg / L, the leaching amount of heavy metal Cd is <0.003mg / L, and all properties meet the national standards. Example

[0035] The gradient-pore structure of the waste incinerator slag foamed ceramic comprises the following raw materials (by mass): 65 parts of municipal solid waste incinerator slag, 5 parts of low-quality kaolin, 25 parts of quartz tailings, 12 parts of feldspar, 1 part of talc, 0.3 parts of gradient foaming agent (including 0.14 parts of CaCO3, 0.08 parts of Fe2O3, and 0.08 parts of SiC), and 2.5 parts of additives (2.0 parts of calcium hydroxide and 0.5 parts of sodium hydroxide).

[0036] In this embodiment, the two-stage firing method for the gradient pore structure waste incinerator slag foamed ceramic includes the following steps: S1. Pre-treat the ash from municipal solid waste incineration plants; Specifically, the slag is washed with water at a ratio of 1:0.9 to fully leach out the chloride ions in the slag. The slag is then dehydrated by pressure filtration to obtain a slag filter cake, and the filtrate is evaporated and crystallized. After washing, the moisture content of the slag is controlled at 9%, and the total chloride ion content is controlled at 1.1%.

[0037] S2: Coarse crushing, ingredient mixing and initial mixing; The above raw materials are coarsely crushed to ensure that the particle size is no larger than 2mm. Then, each raw material is accurately measured according to the formula ratio to obtain a mixture.

[0038] S3: The mixture is ground and crushed using a dry process.

[0039] S4: Prepare powder by dry grinding of raw materials to make the particle size of the mixed powder ≤200 mesh. In this step, the particle size distribution of the mixed powder is as follows: 40-60 mesh accounts for 18%, 60-80 mesh accounts for 58%, 80-100 mesh accounts for 20%, and greater than 100 mesh accounts for 4%.

[0040] S5: Fabric preparation and drying preheating. The mixed powder is loaded into the mold and dried and preheated in a drying kiln at a temperature of 500℃ for 2.5 hours.

[0041] S6: The material is placed in a tunnel kiln for two-stage high-temperature firing and shaping; First, the first stage of firing is carried out, with the temperature set at 900℃. Pre-foaming is performed in a reducing atmosphere (CO concentration 10%), and the temperature is held for 1.2 hours. The heating rate is 180℃ / h. Then, the second firing stage is carried out, with the temperature set at 1200℃, and densification and pore structure stabilization are carried out in an oxidizing atmosphere (oxygen-rich air, O2 concentration 25%), and the temperature is held for 1.2h, with a heating rate of 280℃ / h. Finally, the temperature was reduced from 1200℃ to 600℃ at a cooling rate of 550℃ / h, and then reduced from 600℃ to room temperature at a cooling rate of 350℃ / h.

[0042] S7: Inspect, select, and trim the semi-finished foamed ceramic panels to obtain the final finished product and put it into storage.

[0043] The foamed ceramic product prepared according to the raw materials and method in this embodiment has a uniform cross-sectional pore structure, and the relevant test data are as follows: The closed-cell rate reached 97.1%, the compressive strength was 14.8 MPa, the thermal conductivity was 0.21 W / (m·K), the leaching amount of heavy metal Pb was <0.006 mg / L, and the leaching amount of heavy metal Cd was <0.002 mg / L. The performance indicators were slightly better than those of Example 1, and all performance indicators met the national standard requirements.

[0044] To demonstrate the superiority of each indicator in the above embodiments, a comparative example is provided below for reference. In this comparative example, the foamed ceramics are made using a traditional single foaming agent and single-stage firing process.

[0045] Comparative Example The raw materials (by mass parts) of the foamed ceramic described in this comparative example include 55 parts of municipal solid waste incineration slag, 8 parts of low-quality kaolin, 32 parts of quartz tailings, 8 parts of feldspar, 2 parts of talc, 0.25 parts of a single foaming agent (SiC), and 2 parts of additives (1.5 parts of calcium hydroxide and 0.5 parts of sodium carbonate). The slag pretreatment conditions are the same as in Example 1.

[0046] The first half of its process flow is the same as S1-S4 in Example 1, and the second half of the process is as follows: S5. Fabrication and Drying Preheating: Load the mixed powder into the mold and preheat it in a drying kiln at a temperature of 450℃ for 3 hours.

[0047] S6. Single-stage high-temperature firing: The material is placed in a tunnel kiln for calcination. The firing process was carried out at 1150℃ in an air atmosphere for 2.5 hours, with a heating rate of 200℃ / h. The temperature was lowered from 1150℃ to 600℃ at a rate of 500℃ / h; finally, it was lowered from 600℃ to room temperature at a rate of 300℃ / h.

[0048] S7. Cutting, inspection, and product warehousing: The semi-finished foamed ceramic panels are sorted and trimmed to obtain the final product.

[0049] To visually demonstrate the performance differences between the embodiments and comparative examples, a table is provided below for comparison:

[0050] As can be seen from the table, compared with the foamed ceramic products prepared in Examples 1 and 2, the foamed ceramic products prepared in the comparative example have poor pore structure uniformity, with open pores and large pores, and a closed pore rate of only 91.8%. The compressive strength is 7.8 MPa, the thermal conductivity is 0.32 W / (m·K), the leaching amount of heavy metal Pb is 0.045 mg / L, the leaching amount of heavy metal Cd is 0.028 mg / L, the product appearance has obvious cracks and deformation, some products collapsed during firing, and the pass rate is only 65%.

[0051] The gradient pore structure waste incinerator slag foamed ceramic and its two-stage firing method described in the above embodiments optimize the existing process formula and use municipal solid waste incinerator slag as the main raw material for producing foamed ceramics. This not only reduces the sintering temperature and energy cost of foamed ceramics, but also utilizes the synergistic effect between components to solidify heavy metals in the slag, preventing leaching and achieving the harmlessness and resource utilization of the slag.

[0052] During the production process, water consumption can be accurately calculated, and a related material recycling system can be adopted, so that the entire production process can save resources and energy to the greatest extent, and the density of the produced ceramic products can be controlled to meet different needs.

[0053] During the manufacturing process, a two-stage firing process combined with a gradient foaming agent is adopted to precisely control the foaming behavior and iron valence state transformation in different temperature ranges. This solves the problems of low closed-cell rate and uneven pore size distribution caused by the difficulty in controlling the iron valence state transformation in slag and the inability of a single foaming agent to meet the foaming requirements of slag in different temperature ranges. This enables the preparation of high-performance slag-based foamed ceramics.

[0054] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A gradient-pore structure foamed ceramic from waste incinerator slag, characterized in that, The raw material components, by mass parts, include: 50-70 parts of municipal solid waste incinerator slag, 0-15 parts of kaolin, 20-40 parts of tailings slag, 3-15 parts of feldspar, 0-5 parts of talc, 0.2-0.35 parts of gradient foaming agent, and 1-3 parts of additives.

2. The gradient pore structure foamed ceramic for waste incineration slag according to claim 1, characterized in that: The gradient foaming agent is composed of a low-temperature foaming agent, a medium-temperature foaming agent, and a high-temperature foaming agent. The low-temperature foaming agent produces CO2 gas in the temperature decomposition range of 600-800℃, the medium-temperature foaming agent produces CO2 gas in the temperature decomposition range of 800-1000℃, and the high-temperature foaming agent produces CO gas in the temperature decomposition range of 1100-1250℃. The three gases work synergistically in different temperature ranges to form a uniform gradient pore structure. The ratio of the low-temperature foaming agent, the medium-temperature foaming agent, and the high-temperature foaming agent is 1-1.5:0.5-1:0.5-1.

3. The gradient pore structure waste incinerator slag foamed ceramic according to claim 2, characterized in that: The low-temperature foaming agent is CaCO3, the medium-temperature foaming agent is Fe2O3, and the high-temperature foaming agent is SiC.

4. The gradient pore structure foamed ceramic for waste incineration slag according to claim 1, characterized in that: The additive is selected from at least one of calcium hydroxide, sodium hydroxide, and sodium carbonate.

5. A two-stage firing method for foamed ceramics made from gradient-pore structure waste incinerator slag, characterized in that, Includes the following steps: S1. Pre-treat the slag from municipal solid waste incineration furnaces to obtain slag filter cake; S2. The slag filter cake, together with other required raw materials, is coarsely crushed, batched, and initially mixed to obtain a mixture. S3. Grind and crush the mixture using a wet or dry process to form fine crushed material; S4. The finely crushed material is spray-dried or dry-dried to obtain a mixed powder. S5. The mixed powder is molded, distributed, dried, and preheated. S6. The preheated material is placed into a tunnel kiln for two-stage high-temperature firing to obtain a semi-finished foamed ceramic board. S61. Perform the first stage of firing, set the temperature to 800-950℃, pre-foam in a reducing atmosphere, hold for 0.5-1.5h, and raise the temperature at a rate of 100-200℃ / h. S62. Perform the second stage of firing at a temperature of 1100-1250℃. Densification and pore structure stabilization are carried out in an oxidizing atmosphere. Hold the temperature for 1-2 hours and the heating rate is 200-300℃ / h. S63. First, cool down to 600℃ at a rate of 400-600℃ / h, then cool down from 600℃ to room temperature at a rate of 200-400℃ / h. S7. Inspect, select, and trim the foamed ceramic board semi-finished product to obtain the finished product and put it into storage.

6. The method for preparing gradient-pore structured foamed ceramics from waste incinerator slag according to claim 5, characterized in that: The pretreatment in step S1 includes washing and pressing the municipal solid waste incinerator slag with water. The ratio of municipal solid waste incinerator slag to water is 1:0.9-1. The moisture content of the slag filter cake is controlled to be less than 12%, and the total chloride ion content is controlled to be less than 2%.

7. The method for preparing gradient-pore structured foamed ceramics from waste incinerator slag according to claim 5, characterized in that: The maximum particle size of the mixture is 2 mm, and the particle size of the mixed powder is no greater than 200 mesh.

8. The method for preparing gradient-pore structured foamed ceramics from waste incinerator slag according to claim 5, characterized in that: In step S5, the preheating temperature is 100-600℃ and the preheating time is 2-4 hours.

9. The method for preparing gradient-pore structured foamed ceramics from waste incinerator slag according to claim 5, characterized in that: In step S5, the pressure for pressing the powder in the mold is adjusted according to the density of the product to be produced. The pressure adjustment range is 0-12MPa, and the density of the product to be produced is controlled between 0.3 and 1.0t / m³.

10. The method for preparing gradient-pore structured foamed ceramics from waste incinerator slag according to claim 5, characterized in that: The reducing atmosphere in step S6 is a mixed gas with a CO concentration of 5%–15%, and the oxidizing atmosphere is air or oxygen-enriched air.

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