A method for efficient utilization of fly ash of all particle sizes based on particle size grading

Abstract

The application discloses a fly ash full-size efficient utilization method based on granularity grading, which comprises the following steps: fly ash is subjected to grading pretreatment; high-activity fine-size fly ash is uniformly mixed with sintering method red mud, an alkaline activator and water to obtain slurry A; and / or low-activity coarse-size fly ash is subjected to mechanical grinding and alkali-thermal activation with Bayer process red mud and an alkaline activator to obtain a precursor powder, which is then uniformly mixed with water to obtain slurry B; the slurry A and / or the slurry B is subjected to injection molding, vibration forming and curing to obtain a geopolymer product. The application replaces the traditional overall mechanical grinding or overall (alkali) thermal activation of fly ash raw materials by means of fly ash grading utilization, has the advantages of low energy consumption, low alkali consumption, high production efficiency, full use of the differences in the characteristics of different particle sizes of fly ash and the like, and makes up for the defects of high pretreatment cost and difficulty in comprehensive utilization of solid waste in the production of previous geopolymer materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of solid waste resource utilization, and particularly relates to a full-size efficient utilization method of fly ash based on particle size grading. BACKGROUND

[0002] Since coal is the main raw material for thermal power generation, fly ash is inevitably generated during power generation. Fly ash is a solid waste generated during power generation in power plants, which can easily pollute the surrounding environment if not disposed of in time. The current global production of fly ash is about 363 million tons per year, and the application of low-calcium fly ash in geopolymer has been widely studied because of its high content of SiO2 and Al2O3 and potential pozzolanic activity. At present, many enterprises pay great attention to the research and utilization of fly ash, hoping to further realize the transformation of waste into treasure.

[0003] In the utilization process of fly ash, the activation method usually plays a crucial role in the strength and microstructure development of fly ash-based geopolymer. Chinese patent CN202211511957.3 proposes a method for preparing fly ash-based geopolymer with adjustable mechanical properties using ethanol or water-assisted ground fly ash as raw material. Chinese patent CN202010424227.4 uses alkaline activator and acid activator to modify and treat fly ash to improve the activity of fly ash and prepare high-performance materials. As can be seen, the traditional method is to improve the reactivity of fly ash by overall amorphization of inert minerals (quartz, mullite, feldspar, etc.) (for example: alkali-thermal activation, mechanical activation, etc.), but this not only consumes a large amount of energy and reagents, but also has limited effect on the improvement of the mechanical properties of fly ash-based geopolymer. Especially in the selection of physical activation methods, the current main method involves mechanical grinding activation. During the grinding process, mechanical force and mechanical heat effect act on the fly ash, and the improvement of the activity of the fly ash is affected by the two effects, among which the mechanical force plays a major role. After mechanical grinding, the particle size of fly ash is effectively reduced, and the specific surface area is increased, so that the reaction contact surface is increased, and the surface properties are obviously improved. Therefore, mechanical grinding can to some extent stimulate the activity of fly ash, especially its chemical reactivity. However, mechanical grinding generally has problems such as long grinding time, low activation efficiency, and insufficient overall activity improvement. Because of the significant difference in particle size and reactivity between different particle sizes of fly ash, the mechanical grinding process not only has little gain effect on the high-activity fine fly ash particles themselves, but also has little effect on the activity improvement of the relatively inert coarse fly ash particles. In addition, the crushing of coarse fly ash particles during the grinding process releases a large amount of impurities to consume the alkaline reagent for alkali activation reaction, which in turn reduces the probability of collision between high-activity fine fly ash particles and alkali, resulting in a high-alkali-consumption state of the reaction system.

[0004] So far, the above problems have not been well solved, so according to the characteristics of fly ash, exploring a low-alkali consumption and high-efficiency resource disposal method and establishing a comprehensive resource utilization system are important directions to improve the resource utilization value and large-scale utilization degree of fly ash solid waste resources. SUMMARY

[0005] The purpose of the present application is to overcome the above technical deficiencies, and to provide a fly ash full particle size efficient utilization method based on particle size grading, which solves the technical problems of high energy consumption, high alkali consumption and low energy efficiency in the fly ash activation process in the prior art.

[0006] In a first aspect, the present application provides a fly ash full particle size efficient utilization method based on particle size grading, comprising the following steps:

[0007] S1, by classifying and pretreating fly ash, obtaining high-activity fine particle size fly ash A and low-activity coarse particle size fly ash B;

[0008] S2, uniformly mixing the high-activity fine particle size fly ash A with sintered red mud to obtain precursor powder A, and then uniformly mixing the precursor powder A, an alkali activator A and water A to obtain slurry A;

[0009] and / or, mechanically grinding the low-activity coarse particle size fly ash B with Bayer red mud and an alkali activator B to obtain pretreated raw materials, and then alkali-thermal activating the pretreated raw materials to obtain precursor powder B, and then uniformly mixing the precursor powder B with water B to obtain slurry B;

[0010] S3, injection molding, vibration forming and curing to a specified age of the slurry A and / or the slurry B to obtain geopolymer product A and / or geopolymer product B.

[0011] In a second aspect, the present application provides a fly ash and red mud geopolymer, which is obtained by the fly ash full particle size efficient utilization method based on particle size grading provided in the first aspect of the present application.

[0012] Compared with the prior art, the present application has the following advantages:

[0013] The present application replaces the traditional whole mechanical grinding or whole (alkali) thermal activation of fly ash raw materials by classifying and utilizing fly ash, which has the advantages of low energy consumption, low alkali consumption, high production efficiency, full use of the characteristics of each particle size of fly ash, etc., and makes up for the shortcomings of high pretreatment cost and difficulty in fully utilizing solid waste in the production of previous geopolymer materials. In addition, the present application not only widens the utilization way of different types of red mud hazardous waste produced under different alumina production processes, but also utilizes the excellent performance of geopolymer in heavy metal solidification to seal heavy metal ions and radioactive elements in red mud, avoiding environmental damage. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of one embodiment of the method for efficient utilization of fly ash of all particle sizes based on particle size classification provided by the present invention.

[0015] Figure 2 These are scanning electron microscope images of the fly ash raw materials used in the embodiments and comparative examples of this invention;

[0016] Figure 3 This is the particle size distribution curve of the fly ash raw material used in the embodiments and comparative examples of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0018] In the utilization of fly ash, the traditional fly ash activation process is energy-intensive, costly, energy-efficient, and not very effective. It also fails to consider the significant differences in characteristics between different particle sizes of fly ash and fails to leverage the advantages of each particle size. At the same time, traditional fly ash requires a large amount of alkaline activator and has a harsh curing system in the geopolymer preparation stage, which is not conducive to industrial promotion.

[0019] Based on this, the present invention is proposed.

[0020] In a first aspect, the present invention provides a method for efficient utilization of fly ash across all particle sizes based on particle size classification, comprising the following steps:

[0021] S1. By classifying and pretreating fly ash, high-activity fine-grained fly ash A and low-activity coarse-grained fly ash B are obtained.

[0022] S2. Mix the highly active fine-grained fly ash A with the sintering red mud evenly to obtain precursor powder A. Then mix the precursor powder A, alkaline activator A and water A evenly to obtain slurry A.

[0023] And / or, the low-activity coarse-grained fly ash B is mechanically ground with Bayer red mud and alkaline activator B to obtain pretreated raw materials. The pretreated raw materials are then alkali-thermal activated to obtain precursor powder B. The precursor powder B is then mixed evenly with water B to obtain slurry B.

[0024] S3. Slurry A and / or slurry B are injected into molds, vibrated to form, and cured to the specified age to obtain geopolymer product A and / or geopolymer product B.

[0025] The present application can obtain fine particle size fly ash with excellent activity by particle size grading, and then use the high-activity fine particle size fly ash and sintered red mud as raw materials, and use the characteristics of the sintered red mud, i.e., rich in active calcium source and high alkalinity, to prepare a cementing material with excellent performance under the conditions of normal temperature and low alkalinity activator dosage. The low-activity coarse particle size fly ash is disposed together with the Bayer process red mud by taking advantage of the characteristics of the Bayer process red mud, i.e., containing high silicon aluminum components and alkaline substances: the two are mechanically ground and alkali-activated to prepare precursor powder which can be cast and formed by adding water. The present application not only reduces energy loss, but also solves the technical barriers of site construction of geopolymer, and is conducive to industrialization.

[0026] In the embodiment, the fly ash is F-class fly ash, and the main chemical components are as follows: SiO2 50-60%, Al2O3 20-30%, and CaO 2-4%.

[0027] In some specific embodiments of the present application, the D90 particle size of the fly ash is less than 100 μm.

[0028] In the embodiment, the grading particle size boundary of the high-activity fine particle size fly ash A and the low-activity coarse particle size fly ash B is 33-45 μm after particle size grading.

[0029] In the embodiment, the present application does not limit the method of pre-treatment by grading, and a person skilled in the art can select according to the actual situation. For example, the method of pre-treatment by grading includes but is not limited to mechanical screening, hydrocyclone grading, etc.

[0030] In the embodiment, the main chemical components of the sintered red mud are as follows: SiO2 10-20%, Al2O3 5-10%, and CaO 30-40%.

[0031] In the embodiment, the main chemical components of the Bayer process red mud are as follows: SiO2 15-20%, Al2O3 20-30%, and CaO 10-20%.

[0032] In the embodiment, the alkaline activator A and / or the alkaline activator B are at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.

[0033] In the embodiment, the mass ratio of the high-activity fine particle size fly ash A to the sintered red mud in the precursor powder A is 5:(1-3).

[0034] In the embodiment, the mass ratio of the precursor powder A to the alkaline activator A in the slurry A is 1:(0.09-0.16).

[0035] In the embodiment, the mass ratio of the low-activity coarse-grained fly ash B, the Bayer red mud and the alkaline activator B in the pretreated raw material is 7:(2-4):(1.6-2.4).

[0036] In the embodiment, the mechanical grinding is performed by using a vibration grinder, and the grinding time is 1-6 min.

[0037] In the embodiment, the temperature of the alkali-thermal activation is 500-600℃, and the time of the alkali-thermal activation is 60-120 min.

[0038] In the embodiment, the fluidity of the slurry A and / or the slurry B is controlled to be 120-130 mm. The present application does not limit the amount of water, and the person skilled in the art can select according to the actual situation to ensure that the slurry reaches the specified fluidity, i.e., the mortar fluidity is measured to be 120-130 mm according to GB / T 2419-2005 "Cement Mortar Fluidity Determination Method".

[0039] In the embodiment, the curing temperature is room temperature (generally 20-30℃). The present application does not limit the specified age, and the person skilled in the art can select according to the actual situation. For example, the specified age can be 3d, 7d, 14d, 28d, etc.

[0040] In a second aspect, the present application provides a fly ash and red mud based geopolymer, which is obtained by the full-grain high-efficiency utilization method of fly ash based on particle size grading provided in the first aspect of the present application.

[0041] To avoid redundancy, the raw materials of the following examples and comparative examples of the present application are summarized as follows:

[0042] Please refer to Figures 2-3 , the fly ash is F-class fly ash, and the mass percentages of the main chemical components are as follows: SiO2 51.09%, Al2O3 27.89%, CaO 3.56%; the D90 particle size of the fly ash is 84.482μm.

[0043] The main chemical components of the sintering process red mud are as follows: SiO2 18.60%, Al2O3 7.72%, CaO 37.90%;

[0044] The main chemical components of the Bayer red mud are as follows: SiO2 19.34%, Al2O3 24.84%, CaO 13.61%.

[0045] Example 1

[0046] Step one: The fly ash is pretreated by particle size grading to obtain high-activity fine-grained fly ash A with a particle size less than 38μm and low-activity coarse-grained fly ash B with a particle size greater than 38μm.

[0047] Step two: uniformly mix the high-activity fine-particle fly ash A and sintered red mud in a mass ratio of 5:2 to obtain precursor powder A;

[0048] Step three: add water to the precursor powder A and NaOH medicament in a mortar mixer and fully stir to obtain slurry A with a flowability of 125 mm and a uniform texture; wherein the mass ratio of the precursor powder A to the NaOH medicament is 1:0.12;

[0049] Step four: mix the low-activity coarse-particle fly ash B, Bayer red mud, and sodium hydroxide particles in a mass ratio of 7:3:2, then grind the mixture through a vibration grinder for 3 min to obtain pretreated raw materials, and place the pretreated raw materials in a muffle furnace for alkali-heat activation, with a calcination temperature of 550°C and a calcination time of 90 min, to obtain precursor powder B;

[0050] Step five: add water to the precursor powder B in a mortar mixer and fully stir to obtain slurry B with a flowability of 125 mm and a uniform texture;

[0051] Step six: cast the slurry A and the slurry B into 20mm*20mm*20mm molds and vibrate to form, and after being placed at room temperature for 28 days, high-performance geopolymer products A and geopolymer products B can be obtained;

[0052] The 28-day compressive strength value of the high-performance geopolymer product A obtained by the method is 45.56 MPa, and the 28-day compressive strength value of the geopolymer product B is 34.78 MPa.

[0053] Example 2

[0054] Step one: pretreat the fly ash by particle size classification to obtain high-activity fine-particle fly ash A with a particle size of less than 33μm and low-activity coarse-particle fly ash B with a particle size of more than 33μm;

[0055] Step two: uniformly mix the high-activity fine-particle fly ash A and sintered red mud in a mass ratio of 5:1 to obtain precursor powder A;

[0056] Step three: add water to the precursor powder A and NaOH medicament in a mortar mixer and fully stir to obtain slurry A with a flowability of 120 mm and a uniform texture; wherein the mass ratio of the precursor powder A to the NaOH medicament is 1:0.09;

[0057] Step four: mix the low-activity coarse-particle fly ash B, Bayer red mud, and sodium hydroxide particles in a mass ratio of 7:2:1.6, then grind the mixture through a vibration grinder for 1 min to obtain pretreated raw materials, and place the pretreated raw materials in a muffle furnace for alkali-heat activation, with a calcination temperature of 500°C and a calcination time of 60 min, to obtain precursor powder B;

[0058] Step five: the precursor powder B is fully stirred in a mortar mixer with water to obtain slurry B with a flowability of 120 mm and a uniform texture;

[0059] Step six: slurry A and slurry B are respectively cast into a 20mm*20mm*20mm mold and vibrated to form, and high-performance geopolymer products A and geopolymer products B can be obtained after being placed at room temperature for 28 days of curing;

[0060] The 28-day compressive strength value of the high-performance geopolymer product A obtained by the method is 43.77 MPa, and the 28-day compressive strength value of the geopolymer product B is 33.95 MPa.

[0061] Example 3

[0062] Step one: fly ash is pretreated by particle size classification to obtain high-activity fine particle size fly ash A with a particle size of less than 45 μm and low-activity coarse particle size fly ash B with a particle size of more than 45 μm;

[0063] Step two: the high-activity fine particle size fly ash A is uniformly mixed with the sintered red mud at a mass ratio of 5:3 to obtain precursor powder A;

[0064] Step three: the precursor powder A and the NaOH medicament are fully stirred in a mortar mixer with water to obtain slurry A with a flowability of 130 mm and a uniform texture; wherein the mass ratio of the precursor powder A to the NaOH medicament is 1:0.16;

[0065] Step four: the low-activity coarse particle size fly ash B, the Bayer process red mud, and the sodium hydroxide particles are mixed at a mass ratio of 7:4:2.4 and then ground by a vibration grinder for 6 min to obtain pretreated raw materials, and the pretreated raw materials are placed in a muffle furnace for alkali heat activation, with a calcination temperature of 600℃ and a calcination time of 120 min, to obtain precursor powder B;

[0066] Step five: the precursor powder B is fully stirred in a mortar mixer with water to obtain slurry B with a flowability of 130 mm and a uniform texture;

[0067] Step six: slurry A and slurry B are respectively cast into a 20mm*20mm*20mm mold and vibrated to form, and high-performance geopolymer products A and geopolymer products B can be obtained after being placed at room temperature for 28 days of curing;

[0068] The 28-day compressive strength value of the high-performance geopolymer product A obtained by the method is 42.74 MPa, and the 28-day compressive strength value of the geopolymer product B is 32.60 MPa.

[0069] Comparative Example 1

[0070] The difference compared with Example 1 is only that the fly ash particles are not subjected to the classification pretreatment, and the overall operation steps are as follows:

[0071] Step one: the fly ash particles are mixed with the sintered red mud in a mass ratio of 5:2 to obtain a precursor powder;

[0072] Step two: the precursor powder and NaOH reagent are fully stirred with water in a mortar mixer to obtain a slurry with a fluidity of 125 mm and a uniform texture; wherein the mass ratio of the precursor powder to the NaOH reagent is 1:0.12;

[0073] Step three: the slurry is cast into a 20mm*20mm*20mm mold and vibrated to form, and a geopolymer product can be obtained after being placed at room temperature for 28 days;

[0074] The 28-day compressive strength value of the fly ash and sintered red mud geopolymer product obtained by this method is only 24.29MPa. This is because the coarse particles contained in the fly ash are not activated by alkali heat, and there are a large amount of impurities and poor activity, which not only consumes a large amount of alkaline activator in the reaction process of geopolymer, but also has no help to the formation of gel phase.

[0075] Comparative Example 2

[0076] The difference compared with Example 1 is only that the fly ash particles are not subjected to the classification pretreatment, and the overall operation steps are as follows:

[0077] Step one: the fly ash particles are mechanically vibrated for 3 minutes, and then sieved to obtain fine fly ash particles with a particle size of less than 38μm;

[0078] Step two: the fine fly ash particles are mixed with the sintered red mud in a mass ratio of 5:2 to obtain a precursor powder;

[0079] Step three: the precursor powder and NaOH reagent are fully stirred with water in a mortar mixer to obtain a slurry with a fluidity of 125 mm and a uniform texture; wherein the mass ratio of the precursor powder to the NaOH reagent is 1:0.12;

[0080] Step four: the slurry is cast into a 20mm*20mm*20mm mold and vibrated to form, and a geopolymer product can be obtained after being placed at room temperature for 28 days;

[0081] The 28-day compressive strength value of the fly ash and sintered red mud geopolymer product obtained by this method is 30.77MPa. This is because the mechanical vibration cannot fully activate the inert components such as quartz and mullite in the fly ash particles, and the change of the fly ash after mechanical vibration is only limited to the particle size and surface, so the improvement of the mechanical properties of the geopolymer product is limited.

[0082] Comparative Example 3

[0083] Compared with Example 1, the only difference is that the fly ash particles are not subjected to the pretreatment of grading, and the overall operation steps are as follows:

[0084] Step one: the fly ash particles, Bayer red mud and sodium hydroxide particles are mixed in a mass ratio of 7:3:2 and then ground by a vibration grinder for 3 min to obtain pretreated raw materials, and the pretreated raw materials are placed in a muffle furnace for alkali heat activation, the calcination temperature is 550°C, and the calcination time is 90 min, to obtain a precursor powder;

[0085] Step two: the precursor powder is fully stirred with water in a mortar mixer to obtain a slurry with a uniform texture and a fluidity of 125 mm;

[0086] Step three: the slurry is cast into a 20mm*20mm*20mm mold and vibrated to form a shape, and after being placed at room temperature for 28 days, a geopolymer product is obtained;

[0087] The 28-day compressive strength value of the fly ash and Bayer red mud-based geopolymer product obtained by this method is 38.57 MPa. This shows that the overall amorphization treatment has a certain activation effect, but the consumption of alkaline activator and energy is huge, and the activation efficiency of overall mechanical vibration grinding and alkali heat activation is limited, which is difficult to achieve higher strength standards.

[0088] Comparative Example 4

[0089] Compared with Example 1, the only difference is that the particle size grading of high-activity fine particle size fly ash A and low-activity coarse particle size fly ash B has a grading particle size boundary of 20μm.

[0090] The 28-day compressive strength value of the high-performance geopolymer product A obtained by this method is 39.23 MPa, and the 28-day compressive strength value of the geopolymer product B is 35.01 MPa. Compared with Example 1, the compressive strength of geopolymer product A decreases, and the compressive strength difference of geopolymer product B is not significant. This is because when the particle size boundary of the fly ash grading shifts to a smaller size, the overall activity of the fine particle size fly ash has already reached the threshold, and the adverse effects of agglomeration will be reflected on the excessively fine particles, so the compressive strength of the prepared geopolymer product A decreases. The disposal method of geopolymer product B is to co-grind and alkali heat activate the relatively low-activity coarse particle fly ash and Bayer red mud, and the potential silicon-aluminum components (contained in inert mineral phases such as quartz and mullite) in the raw materials have been fully activated in this activation process, so the compressive strength difference of geopolymer product B is not significant.

[0091] Comparative Example 5

[0092] The difference compared with Example 1 is that the particle size grading boundary between high-activity fine particle size fly ash A and low-activity coarse particle size fly ash B is 74 μm.

[0093] The 28-day compressive strength value of the high-performance geopolymer product A obtained by the method is 37.48 MPa, and the 28-day compressive strength value of the geopolymer product B is 34.35 MPa. Compared with Example 1, the compressive strength of the geopolymer product A decreases significantly, and the compressive strength of the geopolymer product B does not change significantly. This is mainly due to the increase in inert quartz, mullite and other components in the high-activity fine particle size fly ash A after the particle size grading of the fly ash, which reduces the overall activity of the geopolymer precursor powder A, thereby affecting the compressive performance of the final geopolymer product A. The disposal method of the geopolymer product B is to obtain it by mechanical grinding and alkali-thermal activation of relatively low-activity coarse particle size fly ash and Bayer process red mud, and the potential silicon-aluminum components (contained in inert mineral phases such as quartz and mullite) in the raw materials have been fully excited in the activation process, so the compressive strength of the geopolymer product B does not change significantly.

[0094] Comparative Example 6

[0095] The difference compared with Example 1 is that sintering process red mud and Bayer process red mud are not used for synergistic disposal.

[0096] The 28-day compressive strength value of the geopolymer product A obtained by the method is 32.56 MPa, and the 28-day compressive strength value of the geopolymer product B is 28.82 MPa. Compared with Example 1, the compressive strength of both geopolymer products decreases significantly. This is because the active calcium source and alkali source provided by the sintering process red mud in Example 1 can well promote the progress of the geopolymerization reaction, and the silicon-aluminum components and alkali source in the Bayer process red mud can also be used as a component of the gel phase in the geopolymer product after being excited by mechanical grinding and alkali-thermal activation.

[0097] In summary, the present application is based on the significant difference in particle size and reactivity between different particle sizes of fly ash. By particle size grading, high and low activity particles are separated and enriched. Fine particle size fly ash is used as a high activity alkali activated raw material. Coarse particle size fly ash can also be used as an integrated precursor powder for "cement-like" after mechanical grinding and alkali thermal activation. The present application optimizes the raw material pretreatment method based on the particle size grading of fly ash, which has the characteristics of high energy efficiency, simple operation and low total energy consumption. The traditional activation method uses a large amount of mechanical, chemical and thermal treatment methods for the whole particle size fly ash. It has little effect on the high activity fly ash and little effect on the activity improvement of inert fly ash particles. Therefore, by enriching high activity fly ash, the reactivity of geopolymerization is improved, and the separation of low activity fly ash improves the energy efficiency of the activation process, reduces the alkali consumption in the geopolymerization process, and significantly improves the product performance of the geopolymer. This "each gets its own" pretreatment method has significant economic and environmental benefits.

[0098] The specific embodiments of the present application described above do not constitute a limitation on the scope of protection of the present application. Any various other corresponding changes and modifications made in accordance with the technical concept of the present application shall be included in the scope of protection of the claims of the present application.

Claims

1. A method for efficient utilization of a full particle size of fly ash based on particle size classification, characterized by, The method comprises the following steps: S1, obtaining high-activity fine particle fly ash A and low-activity coarse particle fly ash B by grading pretreatment of fly ash; after particle size grading, the grading particle size boundary of the high-activity fine particle fly ash A and the low-activity coarse particle fly ash B is 33-45 μm; S2, uniformly mixing the high-activity fine particle fly ash A and sintering process red mud to obtain precursor powder A, and then uniformly mixing the precursor powder A, alkaline activator A and water A to obtain slurry A; mechanically grinding the low-activity coarse particle fly ash B, Bayer process red mud and alkaline activator B to obtain pretreatment raw material, and then alkali-heat activating the pretreatment raw material to obtain precursor powder B, and then uniformly mixing the precursor powder B and water B to obtain slurry B; S3, injection molding, vibration forming and curing to a specified age of the slurry A and the slurry B to obtain geopolymer product A and geopolymer product B.

2. The method according to claim 1, wherein the full-size-class high-efficiency utilization method of the particle-size-graded fly ash is characterized by, The fly ash is F-class fly ash, and the main chemical components of the fly ash are as follows in mass percentage: SiO2 50-60%, Al2O3 20-30%, and CaO 2-4%; the D90 particle size of the fly ash is less than 100 μm.

3. The method according to claim 1, wherein the method is characterized by, The main chemical components of the sintering process red mud are as follows in mass percentage: SiO2 10-20%, Al2O3 5-10%, and CaO 30-40%; the main chemical components of the Bayer process red mud are as follows in mass percentage: SiO2 15-20%, Al2O3 20-30%, and CaO 10-20%.

4. The method according to claim 1, wherein the method is characterized by, The alkaline activator A and / or the alkaline activator B are at least one selected from sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate.

5. The method according to claim 1, wherein the method is characterized by, In the precursor powder A, the mass ratio of the high-activity fine particle fly ash A to the sintering process red mud is 5: (1-3); in the slurry A, the mass ratio of the precursor powder A to the alkaline activator A is 1: (0.09-0.16).

6. The method according to claim 1, wherein the method is characterized by, In the pretreatment raw material, the mass ratio of the low-activity coarse particle fly ash B, the Bayer process red mud and the alkaline activator B is 7: (2-4): (1.6-2.4).

7. The method according to claim 1, wherein the method is characterized by, The mechanical grinding is performed by using a vibration grinder, and the grinding time is 1-6 min; the temperature of the alkali-heat activation is 500-600 ℃, and the time of the alkali-heat activation is 60-120 min.

8. The method according to claim 1, wherein the method is characterized by, In the slurry A and / or the slurry B, the fluidity of the slurry is controlled to be 120-130 mm; and the curing temperature is room temperature.

9. A fly ash and red mud geopolymer characterised in that, The fly ash and red mud based geopolymer is obtained by the fly ash full particle grade efficient utilization method based on particle size grading according to any one of claims 1-8.

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