Environmentally friendly foamed ceramic and preparation method thereof

Abstract

The present invention belongs to the technical field of building ceramic materials and specifically discloses an environmentally friendly foamed ceramic and a preparation method thereof. The foamed ceramic comprises the following components, by weight: 95-105 parts of a foamed ceramic inorganic raw material, 3-5 parts of methyl cellulose, 0.5-1 part of castor oil, 2-4 parts of glycerin, and 15-18 parts of water; the foamed ceramic inorganic raw material comprises the following components, by weight: 44-50 parts of high-alumina fly ash, 21-30 parts of colemanite, 13-20 parts of albite, and 12-17 parts of quartz. The present invention utilizes the aforementioned environmentally friendly foamed ceramic and a preparation method thereof. The method uses high-alumina fly ash as a solid waste raw material, colemanite, albite, and quartz as mineral raw materials, without the addition of any external foaming agent. A green body is prepared by plastic molding and sintered at a low temperature to ultimately obtain an environmentally friendly foamed ceramic with excellent fireproofing, heat insulation, thermal insulation, and moisture-proof properties.

Description

Technical Field

[0001] The invention belongs to the technical field of building ceramic materials, and particularly relates to an environmentally friendly foamed ceramic and a preparation method thereof. Background Art

[0002] Foamed ceramics, a porous ceramic material characterized by a closed-cell structure, are widely used in the construction industry due to their excellent wall insulation, waterproofing, moisture-proofing, and sound insulation and noise reduction properties. This material not only inherits the lightweight properties of organic porous materials but also combines the high strength and high-temperature resistance of ceramic materials. Using industrial solid waste fly ash as raw material to produce foamed ceramics can effectively reduce solid waste pollution to soil, water sources, and other ecological environments, while also realizing waste resource utilization. This demonstrates significant market potential in the building ceramics industry and solid waste management.

[0003] However, the inherent properties of fly ash present numerous challenges in the preparation of foamed ceramics. Its particles are fine and lack plasticity, and its chemical composition typically exceeds 70% for SiO₂ and Al₂O₃, resulting in a high degree of refractoriness. Consequently, sintering temperatures for foamed ceramics made primarily from fly ash generally require temperatures exceeding 1150°C. High-temperature sintering not only significantly increases production costs but also increases environmental pollution, contradicting the concept of green production. Furthermore, most foamed ceramic preparation processes rely on expensive external foaming agents such as SiC, AlN, CaCO₃, and MnO₂. While a few studies have utilized the inherent foaming components of solid wastes such as polishing slag and aluminum ash, truly achieving foamed ceramics without the addition of external foaming agents remains extremely rare. Furthermore, the use of foaming agents results in a high volume expansion rate for the foamed ceramics, leading to significant deformation in the final product and increasing the cost of subsequent processing.

[0004] In summary, how to prepare foamed ceramics using fly ash as the primary raw material through a low-temperature sintering process without a foaming agent or foaming component has become a key technical challenge that needs to be overcome in the field of environmentally friendly foamed ceramics. Therefore, the field needs to develop an environmentally friendly foamed ceramic and its preparation method that can effectively solve this problem. Summary of the Invention

[0005] The object of the present invention is to provide an environmentally friendly foamed ceramic and a preparation method thereof. The method uses high-alumina fly ash as a solid waste raw material, colemanite, albite, and quartz as mineral raw materials, without adding any external foaming agent, prepares a green body by a plastic molding method, and sintered at a low temperature to finally obtain an environmentally friendly foamed ceramic with excellent fireproofing, heat insulation, thermal insulation and moisture-proof properties.

[0006] To achieve the above object, the present invention provides an environmentally friendly foamed ceramic comprising the following components by weight: 95-105 parts of foamed ceramic inorganic raw material, 3-5 parts of methyl cellulose, 0.5-1 part of castor oil, 2-4 parts of glycerin, and 15-18 parts of water;

[0007] The foamed ceramic inorganic raw material comprises the following components in parts by weight: 44-50 parts of high-alumina fly ash, 21-30 parts of colemanite, 13-20 parts of albite, and 12-17 parts of quartz.

[0008] Preferably, the weight percentage of Al2O3 in the high-aluminum fly ash is greater than 33wt%, the weight percentage of SiO2 is greater than 46wt%, and the particle size of the high-aluminum fly ash is 400 mesh sieve;

[0009] The particle sizes of the colemanite, albite and quartz are all 200-mesh sieve cuts.

[0010] Preferably, the porosity of the environmentally friendly foamed ceramic is greater than 65%, the closed-pore porosity accounts for more than 92%, and the closed-pore pore size distribution is 0.5-1.2 mm; the compressive strength of the environmentally friendly foamed ceramic is greater than 12 MPa, the water absorption rate is less than 3%, and the bulk density is less than 0.9 g / cm 3 , the thermal conductivity is less than 0.3W / (m·K) at room temperature.

[0011] The present invention also provides a method for preparing an environmentally friendly foamed ceramic, comprising the following steps:

[0012] Step S1, dry-mixing high-alumina fly ash, colemanite, albite, quartz, and methyl cellulose in a mixer according to parts by weight for 1 to 2 hours, and filtering through a 60-mesh sieve to obtain a mixture for later use;

[0013] Step S2, weighing castor oil, glycerin, and water according to parts by weight, shearing, emulsifying, and stirring to obtain a liquid organic additive;

[0014] Step S3, placing the mixture in a kneader, adding a liquid organic additive, kneading for 20 to 30 minutes, and then performing vacuum kneading and aging for 3 to 5 days to obtain a plasticized clay mass;

[0015] Step S4: Extrusion or manual shaping of the plasticized clay mass to obtain various green shapes, with a green density of 1.10-1.15 g / cm 3 The green body is naturally dried and then sintered at a low temperature. After the low temperature sintering, the green body is naturally cooled to room temperature to prepare the environmentally friendly foamed ceramic.

[0016] Preferably, in step S4, the firing system of low-temperature sintering is specifically as follows: the heating rate from room temperature to 800°C is 1-3°C / min, the heating rate from 800°C to the maximum temperature is 5-10min, the maximum temperature is 1000-1030°C, and the temperature is kept at the maximum temperature for 10-30min.

[0017] Preferably, in step S4, the volume expansion rate of the prepared environmentally friendly foamed ceramic before and after sintering is less than 3%.

[0018] The present invention adopts the above-mentioned environmentally friendly foamed ceramic and its preparation method, and the beneficial effects are as follows:

[0019] (1) High-value Utilization of Solid Waste: This invention uses high-aluminum fly ash, an industrial solid waste, as raw material to produce environmentally friendly, lightweight, thermally insulating foamed ceramics, achieving a fly ash utilization rate of over 44%. The environmentally friendly foamed ceramics produced by this invention possess excellent fireproofing, heat insulation, thermal insulation, and moisture-proofing properties, making them widely applicable in the field of building walls, successfully achieving the resource utilization and high-value-added conversion of solid waste.

[0020] (2) Breakthrough in low-cost, low-temperature sintering technology: The foamed ceramics produced by this invention can be sintered at low temperatures of 1000-1030°C, effectively resolving the technical challenge of low-temperature preparation of architectural ceramics from highly refractory fly ash. Through a unique formula design, the raw materials do not contain foaming agents or foaming components, are low-cost and readily available, and the product has a low volume expansion coefficient and requires fewer post-processing steps, significantly reducing production costs and truly achieving low-cost, green production of foamed ceramics.

[0021] (3) Innovative formula and microstructure control: The present invention uses fly ash as the foamed ceramic skeleton, uses colemanite and albite to construct the glass liquid phase body, and uses quartz to adjust the high-temperature viscosity of the glass liquid phase. The foamed ceramic green body begins to melt and form a liquid phase at about 900°C during the heating process. With a certain volume shrinkage, the liquid phase wraps the green body pores to form small-sized closed pores; as the temperature rises to 1000°C, the liquid phase viscosity decreases, and the gas in the closed pores expands due to heat to form large-sized closed pores. The volume expansion generated at this time just offsets the previous volume shrinkage, thereby obtaining a foamed ceramic with a low volume expansion rate. During the cooling stage, quartz and albite crystals precipitate on the solid pore walls, giving the product excellent mechanical properties.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a cross-sectional view of a foamed ceramic sample prepared in Example 1 of an environmentally friendly foamed ceramic and a preparation method thereof according to the present invention;

[0024] Figure 2This is a CT tomographic cross-sectional view of a foamed ceramic sample prepared in Example 1 of an environmentally friendly foamed ceramic and a preparation method thereof according to the present invention;

[0025] Figure 3 This is the XRD diagram of the foamed ceramic sample prepared in Example 1 of the environmentally friendly foamed ceramic and preparation method thereof of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0027] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0028] In the embodiment of the present invention, the high-alumina fly ash contains more than 33 wt% Al2O3 and more than 46 wt% SiO2, and has a particle size of 400-mesh sieve. The mineral raw materials such as colemanite, albite, and quartz are all 200-mesh sieve-free.

[0029] Example 1

[0030] A method for preparing an environmentally friendly foamed ceramic comprises the following steps:

[0031] Step S1, weighing the following raw materials by weight: 95 parts of foamed ceramic inorganic raw materials, 3 parts of methyl cellulose, 0.5 parts of castor oil, 2 parts of glycerin, and 15 parts of water.

[0032] Among them, the following raw materials are weighed in parts by weight from the foamed ceramic inorganic raw materials: 45 parts of high-alumina fly ash, 21 parts of colemanite, 14 parts of albite, and 15 parts of quartz.

[0033] Step S2: dry-mix high-alumina fly ash, colemanite, albite, quartz, and methyl cellulose in a mixer for 1 hour, and pass through a 60-mesh sieve to obtain a mixture for later use.

[0034] Step S3: shearing, emulsifying, and stirring the castor oil, glycerin, and water to obtain a liquid organic additive.

[0035] Step S4: placing the mixture in a kneader, adding a liquid organic additive, kneading for 20 minutes, and then vacuum kneading and aging for 3 days to obtain a plasticized clay mass.

[0036] Step S5: Extrusion or manual molding of the plasticized clay mass to obtain various green compacts with a green compact density of 1.12 g / cm 3After the green body is naturally dried, it is sintered at low temperature. The firing system is as follows: the heating rate from room temperature to 800℃ is 2℃ / min, the heating rate from 800℃ to the maximum temperature is 10min, the maximum temperature is 1010℃, and the temperature is kept at the maximum temperature for 20min. After low temperature sintering, it is naturally cooled to room temperature to prepare the environmentally friendly foamed ceramics. Figure 1-Figure 3 shown.

[0037] Example 2

[0038] A method for preparing an environmentally friendly foamed ceramic comprises the following steps:

[0039] Step S1, weighing the following raw materials by weight: 100 parts of foamed ceramic inorganic raw materials, 4 parts of methyl cellulose, 1 part of castor oil, 2.5 parts of glycerin, and 18 parts of water.

[0040] Among them, the following raw materials are weighed in parts by weight from the foamed ceramic inorganic raw materials: 50 parts of high-alumina fly ash, 25 parts of colemanite, 13 parts of albite, and 12 parts of quartz.

[0041] Step S2: dry-mix high-alumina fly ash, colemanite, albite, quartz, and methyl cellulose in a mixer for 2 hours, and pass through a 60-mesh sieve to obtain a mixture for later use.

[0042] Step S3: shearing, emulsifying, and stirring the castor oil, glycerin, and water to obtain a liquid organic additive.

[0043] Step S4: placing the mixture in a kneader, adding a liquid organic additive, kneading for 30 minutes, and then vacuum kneading and aging for 4 days to obtain a plasticized clay mass.

[0044] Step S5: Extrusion or manual molding of the plasticized clay mass to obtain various green compacts with a green compact density of 1.125 g / cm 3 After natural drying, the green body is sintered at low temperature. The firing schedule is as follows: a heating rate of 2°C / min from room temperature to 800°C, a heating rate of 10 minutes from 800°C to the maximum temperature, and a maximum temperature of 1010°C, followed by a 20-minute hold at the maximum temperature. After low-temperature sintering, the product is naturally cooled to room temperature to produce the environmentally friendly foamed ceramic.

[0045] Example 3

[0046] A method for preparing an environmentally friendly foamed ceramic comprises the following steps:

[0047] Step S1, weighing the following raw materials by weight: 100 parts of foamed ceramic inorganic raw materials, 4 parts of methyl cellulose, 1 part of castor oil, 3 parts of glycerin, and 17 parts of water.

[0048] Among them, the following raw materials are weighed in parts by weight from the foamed ceramic inorganic raw materials: 47 parts of high-alumina fly ash, 28 parts of colemanite, 13 parts of albite, and 12 parts of quartz.

[0049] Step S2: dry-mix high-alumina fly ash, colemanite, albite, quartz, and methyl cellulose in a mixer for 1 hour, and pass through a 60-mesh sieve to obtain a mixture for later use.

[0050] Step S3: shearing, emulsifying, and stirring the castor oil, glycerin, and water to obtain a liquid organic additive.

[0051] Step S4: placing the mixture in a kneader, adding a liquid organic additive, kneading for 20 minutes, and then vacuum kneading and aging for 3 days to obtain a plasticized clay mass.

[0052] Step S5: Extruding or manually shaping the plasticized clay mass to obtain various green shapes, with a green density of 1.14 g / cm 3 After natural drying, the green body is sintered at low temperatures. The firing schedule is as follows: a heating rate of 3°C / min from room temperature to 800°C, an 8-minute heating rate from 800°C to the maximum temperature, and a maximum temperature of 1030°C, followed by a 30-minute hold at the maximum temperature. Following low-temperature sintering, the product is then cooled naturally to room temperature to produce the environmentally friendly foamed ceramic.

[0053] The environmentally friendly foamed ceramics prepared in Example 1, Example 2, and Example 3 were subjected to performance tests, and the test results are shown in Table 1.

[0054] Table 1 Performance indicators of environmentally friendly foamed ceramics prepared in Examples 1 to 3

[0055] ;

[0056] Therefore, the present invention adopts the above-mentioned environmentally friendly foamed ceramic and its preparation method. The method uses high-alumina fly ash as solid waste raw material, and colemanite, sodium feldspar, and quartz as mineral raw materials. Without adding any foaming agent, the green body is prepared by plastic molding method and sintered at low temperature to finally obtain environmentally friendly foamed ceramic with excellent fireproof, heat insulation, thermal insulation and moisture-proof properties.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an environmentally friendly foamed ceramic, characterized in that: The following steps are involved: Step S1, dry-mixing 44-50 parts of high-alumina fly ash, 21-30 parts of colemanite, 13-20 parts of albite, 12-17 parts of quartz, and 3-5 parts of methyl cellulose in a mixer according to weight for 1-2 hours, and filtering the mixture through a 60-mesh sieve to obtain a mixture for later use; Step S2, weighing 0.5-1 parts of castor oil, 2-4 parts of glycerin, and 15-18 parts of water in parts by weight, shearing, emulsifying, and stirring to obtain a liquid organic additive; Step S3, placing the mixture in a kneader, adding a liquid organic additive, kneading for 20 to 30 minutes, and then performing vacuum kneading and aging for 3 to 5 days to obtain a plasticized clay mass; Step S4: Extrusion or manual shaping of the plasticized clay mass to obtain various green shapes, with a green density of 1.10-1.15 g / cm 3 The green body is naturally dried and then sintered at low temperature. After the low temperature sintering, it is naturally cooled to room temperature to prepare the environmentally friendly foamed ceramic. The specific firing system of low-temperature sintering is as follows: the heating rate from room temperature to 800°C is 1~3°C / min, the heating rate from 800°C to the maximum temperature is 5~10min, the maximum temperature is 1000~1030°C, and the temperature is kept at the maximum temperature for 10~30min; The prepared environmentally friendly foamed ceramic has a porosity greater than 65%, a closed-pore porosity greater than 92%, and a closed-pore pore size distribution of 0.5-1.2 mm. The environmentally friendly foamed ceramic has a compressive strength greater than 12 MPa, a water absorption rate less than 3%, and a bulk density less than 0.9 g / cm 3 , the thermal conductivity is less than 0.3W / (m·K) at room temperature.

2. The method for preparing an environmentally friendly foamed ceramic according to claim 1, wherein: The weight percentage of Al2O3 in the high-aluminum fly ash is greater than 33wt%, the weight percentage of SiO2 is greater than 46wt%, and the particle size of the high-aluminum fly ash is 400 mesh screen; The particle sizes of the colemanite, albite and quartz are all 200-mesh sieve cuts.

3. The method for preparing an environmentally friendly foamed ceramic according to claim 1, wherein: In step S4, the volume expansion rate of the prepared environmentally friendly foamed ceramic before and after sintering is less than 3%.

4. An environmentally friendly foamed ceramic prepared by the method for preparing the environmentally friendly foamed ceramic according to any one of claims 1 to 3.

Images