Preparation process of fly ash foamed ceramic with high plasticity
The fly ash preparation process, which is regulated by screening, acid treatment and foaming agent, solves the cost and pollution problems caused by adding clay in the traditional method, and realizes the full fly ash preparation of foam ceramics with high plasticity and high performance.
Patent Information
- Application Number
- CN202510944413.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-09
- Publication Date
- 2025-09-16
AI Technical Summary
Existing methods for preparing foam ceramics require the addition of clay or other binders, which increases production costs and may cause environmental pollution. It is difficult to prepare highly plastic foam ceramics using only fly ash.
Foam ceramics are prepared by screening, removing impurities, fine grinding and acid treatment of fly ash, adding a foaming agent and through compression molding and sintering processes. Appropriate foaming agents and sintering temperatures are selected to control the pore size and mechanical properties, and the addition of clay or other binders is avoided.
The invention realizes the preparation of high plasticity foam ceramics with all fly ash, improves the utilization rate of fly ash, reduces production costs and protects the environment, and at the same time prepares high-performance foam ceramic materials.
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Figure CN120647418A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of fly ash foam ceramic preparation, in particular to a process for preparing fly ash foam ceramic with high plasticity. Background Art
[0002] Fly ash, a solid waste emitted from coal-fired power plants, has a rich chemical composition, primarily including silicon dioxide (SiO2), aluminum oxide (Al2O3), and iron oxide (Fe2O3). Due to its wide availability and low cost, fly ash has broad application potential in areas such as construction materials, road construction, soil improvement, and ceramic manufacturing.
[0003] Foam ceramics is a new type of material with a porous structure. Due to its excellent properties such as light weight, high strength, heat insulation, sound insulation, and high temperature resistance, it is widely used in building insulation, thermal insulation materials, filter materials, catalyst carriers and other fields. Traditional methods for preparing foam ceramics usually require the addition of clay or other binders to improve the plasticity and strength of the material. However, this method not only increases production costs, but may also cause environmental pollution. Therefore, the development of a new process for preparing foam ceramics from fly ash has important economic and environmental significance. Summary of the Invention
[0004] The purpose of the present invention is to provide a process for preparing fly ash foam ceramics with high plasticity to solve the problems raised in the above background technology.
[0005] To achieve the above object, the present invention provides the following technical solution: a process for preparing fly ash foam ceramics with high plasticity, comprising the following steps:
[0006] Step 1: Screening, impurity removal, fine grinding and acid treatment of fly ash;
[0007] Step 2: Ball mill the fly ash according to the design requirements;
[0008] Step 3: Add an appropriate amount of foaming agent to enable the mixture to form a foam structure in the subsequent process;
[0009] Step 4: Add water to the foaming agent and fly ash and mix them;
[0010] Step 5: Place the mixture into a mold and shape it by pressing. At the same time, dry the formed body to remove excess water;
[0011] Step 6: Place the dried green body into a kiln for sintering to solidify it into shape. After sintering, cool it naturally and control the cooling speed to prevent cracking.
[0012] Step 7: Grind and cut the cooled ceramics and conduct quality inspection on the finished products;
[0013] As a further preferred embodiment of the present technical solution, the fly ash is acid-treated in step 1 by using a mixed acid of sulfuric acid and hydrochloric acid to treat the fly ash so as to improve its plasticity and reduce its powder bulk density, and the fly ash after the acid treatment is dried, and the fly ash is fed into a screening device through a feed hopper, and screened using a vibrating screen or an inclined gauze, and the fly ash passes through an electromagnetic plate or an electromagnetic rod to adsorb and separate magnetic impurities;
[0014] As a further preferred embodiment of the present technical solution, in step 2, the fly ash is ground using a ball mill to reduce the particle size of the fly ash and increase the reaction rate between the fly ash and the foaming agent. At the same time, the smaller the particle size of the fly ash, the larger the specific surface area of the fly ash, and the increased contact area with the foaming agent, thereby increasing the reaction rate.
[0015] As a further preferred embodiment of the present technical solution: the foaming agent in step 3 can be selected from CaCO3 and SiC, wherein the pore size generated by CaCO3 and fly ash is small and evenly distributed, and the compressive strength is high, and the pore size generated by SiC and fly ash is large and irregular, and the compressive strength is low;
[0016] As a further preferred embodiment of the present technical solution: in the step 4, the ratio of water to fly ash is between 0.3 and 0.5, and a planetary and vortex mixer is used to stir the slurry, and high-speed foaming is performed in the first stage, and low-speed mixing is performed in the second stage, and the stirring speed is 300 to 500 revolutions per minute, and the stirring time is generally 5 to 10 minutes, until there are no obvious agglomerated particles in the slurry and the slurry is evenly distributed;
[0017] As a further preferred embodiment of the present technical solution: in the step 5, a hydraulic press and a mechanical pressure device are used to inject the mixture into a mold of a preset size for pressing, and the pressing pressure range is 10-30 MPa, and the green body is dried by natural drying. The second drying stage is first low temperature and then high temperature, and the temperature is gradually increased to dry it;
[0018] As a further preferred embodiment of the present technical solution, the sintering in step 6 is divided into three stages: the first stage: room temperature for 45 minutes, 300°C, and heat preservation for 30 minutes; the second stage: room temperature for 60 minutes, 980°C, and heat preservation for 3 hours; the third stage: room temperature for 60 minutes, 1160°C, and heat preservation for 50 minutes, and natural cooling;
[0019] As a further preferred embodiment of the present technical solution, the aspects of the inspection of the cooled ceramic in step seven include: appearance inspection, size inspection, and performance inspection, and the performance inspection includes inspection of strength, water absorption, heat resistance, wear resistance, and chemical stability.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] 1. In the present invention, the fly ash is pre-treated with acid, which significantly improves the plasticity of the fly ash and reduces the bulk density of the powder. This makes it possible to prepare lightweight foam ceramics from fly ash without adding clay or other binders. This treatment method not only improves the utilization rate of fly ash, reduces the emission of industrial waste, but also reduces production costs and ensures environmental protection.
[0022] 2. In the present invention, when CaCO3 is used as a foaming agent, CO2 is generated during the sintering process, resulting in smaller and evenly distributed pores, which helps to improve the compressive strength of the foam ceramic. Secondly, when SiC is used as a foaming agent, the amount of gas generated by the reaction is large, and the pores are large and irregular. Although the porosity is high, the compressive strength is relatively low. By selecting a suitable foaming agent, the pore size distribution and mechanical properties of the foam ceramic can be effectively controlled, thereby preparing a high-performance foam ceramic material.
[0023] 3. In the present invention, through multiple studies, it is concluded that when the amount of the foaming agent SiC is 1.0%, the comprehensive performance of the foam ceramic is better, the pore size, porosity and compressive strength of the foam ceramic can be optimized, and the research can determine that 1160°C is the optimal sintering temperature. At this time, the pore size distribution of the foam ceramic is reasonable, and the compressive strength and bulk density reach a better level. At the same time, the insulation time is determined to be 50 minutes. At this time, the pore size and porosity of the foam ceramic are moderate, and the compressive strength and bulk density are high, thereby ensuring the production of high-performance foam ceramics. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 The present invention is a flow chart of a process for preparing fly ash foam ceramics with high plasticity. DETAILED DESCRIPTION
[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0026] Example
[0027] See also Figure 1 As shown, the present invention provides a technical solution: a process for preparing fly ash foam ceramics with high plasticity, characterized in that it includes the following steps:
[0028] Step 1: Screening, impurity removal, fine grinding and acid treatment of fly ash;
[0029] Step 2: Ball mill the fly ash according to the design requirements;
[0030] Step 3: Add an appropriate amount of foaming agent to enable the mixture to form a foam structure in the subsequent process;
[0031] Step 4: Add water to the foaming agent and fly ash and mix them;
[0032] Step 5: Place the mixture into a mold and shape it by pressing. At the same time, dry the formed body to remove excess water;
[0033] Step 6: Place the dried green body into a kiln for sintering to solidify it into shape. After sintering, cool it naturally and control the cooling speed to prevent cracking.
[0034] Step 7: Grind and cut the cooled ceramics and conduct quality inspection on the finished products;
[0035] In this embodiment, specifically: in step 1, the fly ash is acid-treated using a mixture of sulfuric acid and hydrochloric acid to improve the plasticity of the fly ash and reduce its powder density. In addition, during the fly ash screening process, large particles of fly ash are moved to a storage bin for storage through a screen with an inclination angle of 15° to 30°, while fine fly ash falls through the screen.
[0036] In this embodiment, specifically: in step 2, a ball mill is used to grind the fly ash to reduce the particle size of the fly ash and increase the reaction rate between the fly ash and the foaming agent. When the rotation speed of the ball mill is 400 r / min, the effect of grinding the fly ash is better.
[0037] In this embodiment, specifically: the foaming agent in the step three can be selected from CaCO3 and SiC, wherein the pore size generated by CaCO3 and fly ash is small and evenly distributed, and the compressive strength is high, and the pore size generated by SiC and fly ash is large and irregular, and the compressive strength is low. Secondly, CaCO3 can generate CO2 on the green body to produce pores during the sintering process with the ceramic green body, and also generates CaO, which has a certain effect on the solubility of the green body and plays the role of a flux. As the amount of foaming agent increases, the pore size of the foamed ceramic increases, the porosity and water absorption rate increase, and the bulk density and compressive strength decrease. Therefore, it can be tested that when the amount of foaming agent SiC is 1.0%, the comprehensive performance of the ceramic is better;
[0038] In this embodiment, specifically: in step 4, the ratio of water to fly ash is between 0.3 and 0.5, and a planetary and vortex mixer is used to stir the fly ash. At the same time, high-speed foaming is performed in the first stage, and low-speed mixing is performed in the second stage. The stirring time for high-speed foaming in the first stage is 3 to 5 minutes, and the stirring time for low-speed mixing in the second stage is 5 to 7 minutes.
[0039] In this embodiment, specifically: in the step 5, a hydraulic press and a mechanical pressure device are used to inject the mixture into a mold of a preset size for pressing, and the pressing pressure range is 10 to 30 MPa. The green body is dried by natural drying, and the natural drying process is as follows: the formed green body is placed in a well-ventilated and moderately heated environment, avoiding direct sunlight to prevent rapid drying of the green body surface and cracking. At the same time, a certain distance should be maintained between the ceramic green bodies to ensure air circulation;
[0040] In this embodiment, specifically: the sintering in step 6 is divided into three stages: the first stage: room temperature for 45 minutes, 300°C, and heat preservation for 30 minutes; the second stage: room temperature for 60 minutes, 980°C, and heat preservation for 3 hours; the third stage: room temperature for 60 minutes, 1160°C, and heat preservation for 50 minutes, and natural cooling, and the sintering is carried out using 100% fly ash as the raw material and 1.0% SiC as the foaming agent;
[0041] In this embodiment, specifically: the aspects of the inspection of the cooled ceramic in step seven include: appearance inspection, size inspection, performance inspection, and finally the ceramic can be inspected to have a volume density of 0.78 g / cm3, a compressive strength of 6.05 MPa, a porosity of 78.17%, and a water absorption rate of 1.26%.
[0042] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.
Claims
1. A process for preparing fly ash foam ceramics with high plasticity, characterized in that: The following steps are involved: Step 1: Screening, impurity removal, fine grinding and acid treatment of fly ash; Step 2: Ball mill the fly ash according to the design requirements; Step 3: Add an appropriate amount of foaming agent to enable the mixture to form a foam structure in the subsequent process; Step 4: Add water to the foaming agent and fly ash and mix them; Step 5: Place the mixture into a mold and shape it by pressing. At the same time, dry the formed body to remove excess water; Step 6: Place the dried green body into a kiln for sintering to solidify it into shape. After sintering, cool it naturally and control the cooling speed to prevent cracking. Step 7: Grind and cut the cooled ceramics, and conduct quality inspection on the finished products.
2. The process for preparing a high-plasticity fly ash foam ceramic according to claim 1, characterized in that: In the step 1, the fly ash is subjected to acid treatment using a mixture of sulfuric acid and hydrochloric acid to improve the plasticity of the fly ash and reduce its powder bulk density.
3. The process for preparing a highly plastic fly ash foam ceramic according to claim 2, wherein: In the second step, a ball mill is used to grind the fly ash to reduce the particle size of the fly ash and increase the reaction rate between the fly ash and the foaming agent.
4. The process for preparing a high-plasticity fly ash foam ceramic according to claim 3, characterized in that: The foaming agent in step three can be selected from CaCO3 and SiC, wherein the pore size generated by CaCO3 and fly ash is small and evenly distributed, and the compressive strength is high, while the pore size generated by SiC and fly ash is large and irregular, and the compressive strength is low.
5. The process for preparing fly ash foam ceramics with high plasticity according to claim 4, characterized in that: In the fourth step, the ratio of water to fly ash is between 0.3 and 0.5, and planetary and vortex mixers are used to stir the fly ash. At the same time, high-speed foaming is performed in the first stage and low-speed mixing is performed in the second stage.
6. The process for preparing fly ash foam ceramics with high plasticity according to claim 5, characterized in that: In the step 5, a hydraulic press and a mechanical pressure device are used to inject the mixture into a mold of a preset size for pressing, and the pressing pressure range is 10-30 MPa, and the green body is dried by natural drying.
7. The process for preparing fly ash foam ceramics with high plasticity according to claim 6, characterized in that: The sintering in step six is divided into three stages: the first stage: room temperature for 45 minutes, 300°C, and heat preservation for 30 minutes; the second stage: room temperature for 60 minutes, 980°C, and heat preservation for 3 hours; the third stage: room temperature for 60 minutes, 1160°C, and heat preservation for 50 minutes, and natural cooling.
8. The process for preparing fly ash foam ceramics with high plasticity according to claim 7, characterized in that: The aspects of testing the cooled ceramic in step seven include: appearance testing, size testing, and performance testing.